fix(starlark): toggle the app id the list published, and store a relocatable star_file (#537)

The two review nitpicks left over from #535. Both are still on main after
that merge; the five findings alongside them landed with it.

**The toggle could not find what the list had just shown.**
`_starlark_virtual_plugins` publishes the raw manifest key as
`starlark:<key>`, and `_toggle_starlark_app` passed it back through
`_validate_and_sanitize_app_id`, which lowercases and rewrites every
character outside `[a-z0-9_]`. An app stored as `My-App` was listed as
`starlark:My-App` and looked up as `my_app`, so toggling an app the page
had drawn a moment earlier answered 404. Keys written by
`_install_star_file` are already sanitised, so this only shows up for
manifests written by the starlark-apps plugin itself or edited by hand.

`_validate_starlark_app_path` rejects traversal without rewriting, so it
is the check to use here -- listing and toggling now agree on one key.
The updater also uses `setdefault` rather than indexing: the app is
loaded but its on-disk entry need not exist, and `_update_manifest_safe`
does not catch `KeyError`, so that escaped as a 500 rather than writing
the entry.

**`star_file` was stored absolute.** Readers join it to the app's own
directory -- `_standalone_render_starlark_app` does `app_dir /
app_data.get('star_file', f'{app_id}.star')` -- so the key's default is a
bare filename and an absolute value gave it a second meaning. Since
`Path.__truediv__` discards the left side when the right is absolute,
the manifest was pinned to whatever PROJECT_ROOT installed it, and a
moved or redeployed install could not find its own file. Storing
`dest.name` matches the default and stays relocatable. Read paths are
unchanged, so manifests already holding an absolute path keep working.

7 new tests. Whole suite: no new failures against main, 4013 passed
against 4007.

Co-authored-by: Claude Opus 5 <noreply@anthropic.com>

docs/SCROLL_PERFORMANCE.md

@@ -0,0 +1,266 @@
+# Scroll Performance
+
+How scrolling is paced on this hardware, what was wrong with it, and how to
+configure a plugin so its marquee is smooth.
+
+Measured on a Raspberry Pi 4 driving a 2×128×64 chain (256×64 logical) at
+`limit_refresh_rate_hz: 100`. Numbers below come from that panel.
+
+| | before | after |
+|---|---|---|
+| scroll frame rate | 44–46 fps | **100 fps, locked** |
+| frames ≥ 45 ms | 14–17% | none observed |
+| dominant frame time | 20 ms | **10 ms** |
+| disk cache write (~1 MB) | 14.8 ms | **5.4 ms** |
+
+---
+
+## The one rule that matters
+
+**Motion is smooth when the strip advances a whole number of pixels per panel
+refresh.**
+
+Advancing one pixel per refresh on a 100 Hz panel gives 100 px/s. Slower crisp
+speeds come from holding each frame for several refreshes -- 50 px/s is one
+pixel every second refresh -- which is covered under *Choosing a speed* below.
+A speed that lands on no such combination has to do one of two bad things:
+
+- **blend** two adjacent columns to render a half-step — on pixel-font text
+  this alternates crisp and smeared frames and reads as shimmer, or as the
+  text jumping a pixel ahead of itself;
+- **repeat** a frame — the strip stands still, then jumps, which reads as
+  judder.
+
+Neither is tunable away. Pick a speed that divides evenly.
+
+`src.common.scroll_config` solves this for you: `configure()` snaps a requested
+speed to the nearest one the panel can actually show in whole pixels, and
+`scripts/scroll_speeds.py` prints the full ladder for your hardware.
+
+## Choosing a speed
+
+The crisp speeds are not a fixed list -- they depend on how fast *your* panel
+refreshes, which depends on its size, `pwm_bits`, `gpio_slowdown` and the Pi
+model. A Pi Zero driving a long chain has a completely different set of good
+speeds from a Pi 4 driving a short one.
+
+```bash
+# what can this panel do? (reads your configured refresh rate)
+python3 scripts/scroll_speeds.py
+
+# what does it ACTUALLY manage, rather than what is configured?
+sudo systemctl stop ledmatrix
+sudo python3 scripts/scroll_speeds.py --measure
+sudo systemctl start ledmatrix
+
+# highlight the closest option to the speed you want
+python3 scripts/scroll_speeds.py --want 45
+
+# try one on the panel
+sudo systemctl stop ledmatrix
+sudo python3 scripts/scroll_speeds.py --demo 50
+sudo systemctl start ledmatrix
+```
+
+Sample ladder for a 100 Hz panel:
+
+```
+  20.0 px/s  (1px every 5 refreshes =  20.0 fps, slightly stepped)
+  25.0 px/s  (1px every 4 refreshes =  25.0 fps, slightly stepped)
+  33.3 px/s  (1px every 3 refreshes =  33.3 fps, smooth)
+  50.0 px/s  (1px every 2 refreshes =  50.0 fps, smooth)
+  66.7 px/s  (2px every 3 refreshes =  33.3 fps, smooth)
+ 100.0 px/s  (1px every 1 refresh  = 100.0 fps, smooth)
+```
+
+### How a slow speed stays crisp
+
+`SwapOnVSync(canvas, framerate_fraction)` holds each frame for N panel
+refreshes. **The panel keeps refreshing at its full rate either way**, so
+holding a frame costs nothing in flicker -- it only changes how often a *new*
+image is presented. That is what allows 50 px/s to be one whole pixel every
+second refresh, instead of half a pixel every refresh (which has no good
+rendering, only a choice between blur and judder).
+
+`scroll_config.configure()` snaps the requested speed to the nearest entry on
+the ladder and reports the hold that speed needs. It does **not** apply the
+hold: the hold belongs to a scroll, not to a plugin's lifetime, and plugins
+share one display manager -- one set at construction is reset the moment any
+other plugin finishes scrolling. Apply it yourself when the scroll starts:
+
+```python
+settings = scroll_config.configure(
+    self.scroll_helper,
+    plugin_config=self.config,
+    global_config=self.global_config,
+    display_manager=self.display_manager,   # supplies the panel refresh rate
+)
+
+# ...then, each time this plugin begins scrolling:
+self.display_manager.set_scrolling_state(True, frame_hold=settings.frame_hold)
+```
+
+Passing `display_manager` only lets `configure` read the true refresh rate from
+`display.hardware`, which a plugin config cannot see. Skipping the
+`set_scrolling_state` call is the mistake that matters: the speed still
+resolves, but the panel keeps presenting a new frame every refresh, so a slow
+snapped speed falls back to fractional pixels. Pass `snap_to_crisp=False` to
+keep an exact requested speed and accept the artefacts.
+
+Speeds slower than about 20 px/s are stepped no matter what, because a 1-pixel
+advance at 20 fps is simply a coarse increment. That is the pixel pitch, not a
+software limit; the only way to move in smaller increments is sub-pixel
+blending, which this display does not tolerate (see above).
+
+## Configuring a plugin
+
+Use the shared resolver rather than reading config keys yourself:
+
+```python
+from src.common import scroll_config
+
+settings = scroll_config.configure(
+    self.scroll_helper,
+    plugin_config=self.config,
+    global_config=self.global_config,
+    refresh_hz=scroll_config.refresh_hz_from_config(self.global_config),
+    plugin_logger=self.logger,
+)
+```
+
+It resolves every config shape in one place, applies the speed, and returns
+what it did. Precedence, highest first:
+
+1. `display_options.scroll_speed` + `scroll_delay` — **the recommended form**
+2. `display.scroll_speed` + `scroll_delay` — deprecated shape
+3. `scroll_speed` + `scroll_delay` at the root — legacy flat
+4. `scroll_pixels_per_second` — deprecated
+5. the global `display` block
+6. the built-in default (100 px/s)
+
+`scroll_speed` is pixels per frame and `scroll_delay` is the frame period in
+seconds, so the pair means `scroll_speed / scroll_delay` px/s. The recommended
+config for a 100 Hz panel:
+
+```json
+"display_options": { "scroll_speed": 1.0, "scroll_delay": 0.01 }
+```
+
+### Why the deprecated key ranks below the explicit pair
+
+Because some plugins give `scroll_pixels_per_second` a **schema default**, and
+schema defaults are merged into plugin config. Ranking it above the pair means
+it is always present and always wins, so the documented settings become
+unreachable. That is a real, shipped bug — see
+[ledmatrix-plugins#408](https://github.com/ChuckBuilds/ledmatrix-plugins/issues/408).
+
+If you are writing a plugin: do not give a deprecated key a schema default.
+
+## What was actually wrong
+
+Four independent faults, each found by measurement.
+
+### 1. The frame loop slept on top of a wait it had already done
+
+`display_controller.py` ran the high-FPS loop as `render → SwapOnVSync (blocks
+to the panel's refresh) → time.sleep(0.008) → plugin ticks`. The sleep was
+unconditional and added to a wait that had already happened. Render work
+measured ~4 ms, so each iteration cost ~12 ms against a 10 ms refresh grid —
+every swap missed a refresh and landed on the next one. The loop settled at
+exactly 50 fps while asking for 125, with no headroom, so ~14% of frames
+slipped a further refresh.
+
+Now the loop sleeps only the remainder of the frame budget, with a 1 ms floor
+so plugin threads still get the GIL.
+
+### 2. `SwapOnVSync` held the GIL while blocking
+
+The rgbmatrix binding declares it without `nogil` (unlike `SetPixel`, `Clear`
+and `Fill` immediately above it in `cppinc.pxd`), so the render thread held the
+GIL for the entire vsync wait — most of every frame. Background threads were
+starved into long uninterruptible bursts; a 1.5 MB API response costs ~17 ms to
+parse and ~18 ms to re-encode for the cache, and `json.raw_decode` cannot be
+preempted mid-document. Those bursts are what the render loop then waited on.
+
+Fixed by rebuilding the binding: `scripts/build_rgbmatrix_nogil.sh`.
+
+### 3. Sub-pixel blending was wrong for this display
+
+Enabling it made things worse, not better — see the rule at the top. It is off
+by default and only Vegas mode opts in via `set_sub_pixel_scrolling(True)`.
+
+### 4. Frame-based stepping raced the vsync clock
+
+Frame-based mode gated motion on a wall clock at `1/scroll_delay` steps per
+second. Plugins set `scroll_delay` to the frame period, which puts that
+comparison exactly on its own threshold: a frame arriving a hair early moved
+zero pixels and rendered an identical frame, which dirty-tracking skipped, so
+it returned in ~2 ms and the beat repeated. No `scroll_delay` value tunes this
+out — a shorter delay just trades stalled frames for periodic double-steps.
+
+`ScrollHelper` now accumulates elapsed time in both modes at the same
+configured speed, so position stays proportional to real time.
+
+## Diagnosing a juddery scroller
+
+**`Avg FPS` will lie to you.** It is a 100-frame moving average, and a 2 ms
+duplicate frame plus a 21 ms double-wait average to exactly 10 ms. A ticker
+that is stalling on half its frames still reports a healthy `100.0`.
+
+Look at the **distribution** instead:
+
+```bash
+journalctl -u ledmatrix --since "-10min" --no-pager \
+  | grep -oE "Frame time: [0-9.]+ms" | awk '{print $3}' | sed 's/ms//' \
+  | awk '{printf "%.0f\n", $1}' | sort -n | uniq -c
+```
+
+Reading it, on a 100 Hz panel:
+
+| you see | it means |
+|---|---|
+| everything at 10 ms | healthy |
+| a mode at ~2 ms | **duplicate frames** — the swap was skipped because the image did not change. The scroller is advancing less than one pixel per frame. |
+| a mode at 20/30/50 ms | frames missing refreshes — per-frame work is overrunning, or a background thread is holding the GIL |
+| `Avg FPS` above 100 | duplicates present, unless the scroll cycle has completed and is idling |
+
+Then confirm what the plugin actually loaded — config edits do not always reach
+the running code:
+
+```bash
+journalctl -u ledmatrix --since "-5min" --no-pager | grep -iE "px/s|px/frame"
+```
+
+If a plugin logs its scroll config **twice** with different modes, the second
+line is what is running.
+
+## Rebuilding the binding
+
+```bash
+bash scripts/build_rgbmatrix_nogil.sh              # build into a scratch dir
+sudo bash scripts/build_rgbmatrix_nogil.sh --install
+sudo bash scripts/build_rgbmatrix_nogil.sh --rollback
+```
+
+The build never touches the installed module. `--install` backs up the original
+to `~/rgbmatrix-core.so.ORIGINAL` first, and rolls back automatically if the
+service does not come back healthy. Requires `build-essential`; Cython is
+installed into a cached venv under `~/.cache/ledmatrix-cython`.
+
+Re-run it after upgrading `rpi-rgb-led-matrix`, since a library upgrade
+replaces the patched binding.
+
+## Faster JSON
+
+`src/cache/disk_cache.py` uses `orjson` when it is importable and falls back to
+the stdlib otherwise, so it is optional:
+
+```bash
+sudo pip3 install --break-system-packages orjson
+```
+
+Encoding is where it pays — about 7× on this hardware. Decoding gains far less
+(~1.3× on large payloads) because the cost there is building Python objects,
+not scanning text. That is also why moving parsing to a subprocess does not
+help: `pickle.loads` of the same payload costs 8.1 ms against `json.loads` at
+10.9 ms, so the work just moves rather than disappearing.

plugin-repos/starlark-apps/manager.py

@@ -681,12 +681,18 @@ class StarlarkAppsPlugin(BasePlugin):
                 if app.is_enabled() and app.should_render(current_time):
                     self._render_app(app, force=False)
 
-    def display(self, force_clear: bool = False) -> None:
+    def display(self, force_clear: bool = False) -> bool:
         """
         Display current Starlark app.
 
         This method is called during the display rotation.
         Displays frames from the currently active app.
+
+        Returns False when there is no app to show -- which is the state of
+        every install without Pixlet, and of a fresh one before any app is
+        added. The display controller only skips a mode on a boolean False
+        (it checks isinstance(result, bool)), so returning None held a black
+        panel for the full display_duration instead of rotating on.
         """
         try:
             if force_clear:
@@ -699,20 +705,24 @@ class StarlarkAppsPlugin(BasePlugin):
             if not self.current_app:
                 # No apps available
                 self.logger.debug("No Starlark apps to display")
-                return
+                return False
 
             # Render app if needed
             if not self.current_app.frames:
                 success = self._render_app(self.current_app, force=True)
                 if not success:
                     self.logger.error(f"Failed to render app: {self.current_app.app_id}")
-                    return
+                    return False
 
-            # Display current frame
-            self._display_frame()
+            # Display current frame. The result is propagated: a failed frame
+            # update is not a displayed frame, and returning True regardless
+            # told the controller the mode had rendered, so it held the dead
+            # frame for the whole display_duration instead of rotating on.
+            return self._display_frame()
 
         except Exception as e:
             self.logger.error(f"Error displaying Starlark app: {e}")
+            return False
 
     def _select_next_app(self) -> None:
         """Select the next enabled app for display."""
@@ -835,10 +845,13 @@ class StarlarkAppsPlugin(BasePlugin):
             self.logger.error(f"Error loading frames for {app.app_id}: {e}")
             return False
 
-    def _display_frame(self) -> None:
-        """Display the current frame of the current app."""
+    def _display_frame(self) -> bool:
+        """Display the current frame of the current app.
+
+        :returns: whether a frame actually reached the display manager.
+        """
         if not self.current_app or not self.current_app.frames:
-            return
+            return False
 
         try:
             current_time = time.time()
@@ -856,8 +869,11 @@ class StarlarkAppsPlugin(BasePlugin):
                 )
                 self.current_app.last_frame_time = current_time
 
+            return True
+
         except Exception as e:
             self.logger.error(f"Error displaying frame: {e}")
+            return False
 
     def install_app(self, app_id: str, star_file_path: str, metadata: Optional[Dict[str, Any]] = None, assets_dir: Optional[str] = None) -> bool:
         """

requirements.txt

@@ -55,6 +55,18 @@ packaging>=23.0,<27.0
 #                     range as a hard dependency — keep the two in sync.
 #   pip install 'psutil>=6.0.0,<7.0.0'
 #
+# orjson            — faster JSON for the disk cache
+#                     (src/cache/disk_cache.py). Encoding a ~1MB cache
+#                     record drops from ~12ms to ~1.6ms on a Pi 4, which
+#                     matters because that work holds the GIL and stalls
+#                     the render thread mid-scroll. Falls back to the
+#                     stdlib json when missing — see docs/SCROLL_PERFORMANCE.md.
+#                     The 3.11.6 floor is CVE-2025-67221: orjson.dumps did not
+#                     limit recursion on deeply nested documents, and the disk
+#                     cache encodes payloads parsed straight from third-party
+#                     APIs. 3.11.6 covers the Python range above.
+#   pip install 'orjson>=3.11.6,<4.0'
+#
 # Flask-Limiter     — request rate limiting in web_interface/app.py
 #                     (accidental-abuse protection, not security). The
 #                     web interface starts without rate limiting when

scripts/audit_render_path.py

@@ -0,0 +1,159 @@
+#!/usr/bin/env python3
+"""Find blocking work reachable from a plugin's render path.
+
+`display()` runs on the render thread. Anything slow reached from it stalls the
+panel for its whole duration, and on a vsync-paced loop that is immediately
+visible: a single 15ms call on a 100Hz panel drops a frame, and a network round
+trip freezes the marquee outright.
+
+This has bitten twice already. odds-ticker called `_has_live_games()` every
+frame, whose slow path read the scoreboard cache from disk and parsed JSON per
+enabled league -- one stalled frame every few minutes. soccer-scoreboard timed
+out inside `update()` during a cache refresh. Both were found by staring at
+frame-time histograms, which is a slow way to find a bug that is visible in the
+source.
+
+The audit walks the call graph from `display()` through same-class `self.*`
+methods and reports anything that reaches a known-blocking API. It is a
+heuristic, not a proof: it cannot see through indirection, and a hit is not
+automatically a bug -- a call guarded by an interval check may be fine. It is a
+list of places worth a human look.
+
+    python3 scripts/audit_render_path.py                    # all plugins
+    python3 scripts/audit_render_path.py --dir plugin-repos # a specific tree
+    python3 scripts/audit_render_path.py --plugin odds-ticker
+"""
+from __future__ import annotations
+
+import argparse
+import ast
+import sys
+from pathlib import Path
+
+#: Calls that can block for longer than a frame. Matched on the attribute or
+#: function name, so `requests.get`, `self.session.get` and a bare `get` on a
+#: requests-ish object all register.
+BLOCKING = {
+    "get": "network or cache read",
+    "post": "network",
+    "put": "network",
+    "request": "network",
+    "urlopen": "network",
+    "read": "I/O",
+    "open": "file I/O",
+    "load": "JSON/file parse",
+    "loads": "JSON parse",
+    "dump": "file write",
+    "dumps": "serialise",
+    "sleep": "sleep on the render thread",
+    "run": "subprocess",
+    "check_output": "subprocess",
+    "connect": "network",
+    "download_logo": "network",
+    "_fetch": "fetch",
+}
+
+#: Names that make a hit far more likely to matter.
+HIGH_SIGNAL = ("requests", "urllib", "session", "cache_manager", "subprocess",
+               "socket", "http")
+
+RENDER_ENTRY = "display"
+
+
+class Analyzer:
+    def __init__(self, tree: ast.AST):
+        self.methods: dict[str, ast.FunctionDef] = {}
+        for node in ast.walk(tree):
+            if isinstance(node, (ast.FunctionDef, ast.AsyncFunctionDef)):
+                self.methods.setdefault(node.name, node)
+
+    def calls_in(self, fn: ast.AST):
+        """(self-method names called, blocking hits) inside one function."""
+        self_calls, hits = set(), []
+        for node in ast.walk(fn):
+            if not isinstance(node, ast.Call):
+                continue
+            func = node.func
+            if isinstance(func, ast.Attribute):
+                name = func.attr
+                base = ast.unparse(func.value) if hasattr(ast, "unparse") else ""
+                if base == "self" and name in self.methods:
+                    self_calls.add(name)
+                    continue
+                if name in BLOCKING:
+                    hits.append((name, base, BLOCKING[name], node.lineno))
+            elif isinstance(func, ast.Name) and func.id in BLOCKING:
+                hits.append((func.id, "", BLOCKING[func.id], node.lineno))
+        return self_calls, hits
+
+    def reachable_from(self, entry: str, max_depth: int = 3):
+        """Blocking hits reachable from `entry`, with the path that reaches them."""
+        if entry not in self.methods:
+            return []
+        found, seen = [], set()
+        stack = [(entry, [entry], 0)]
+        while stack:
+            name, path, depth = stack.pop()
+            if name in seen or depth > max_depth:
+                continue
+            seen.add(name)
+            self_calls, hits = self.calls_in(self.methods[name])
+            for hit in hits:
+                found.append((path, hit))
+            for callee in sorted(self_calls):
+                stack.append((callee, path + [callee], depth + 1))
+        return found
+
+
+def audit_file(path: Path):
+    try:
+        tree = ast.parse(path.read_text(encoding="utf-8"))
+    except (OSError, SyntaxError):
+        return []
+    analyzer = Analyzer(tree)
+    return analyzer.reachable_from(RENDER_ENTRY)
+
+
+def main():
+    ap = argparse.ArgumentParser(description=__doc__,
+                                 formatter_class=argparse.RawDescriptionHelpFormatter)
+    root = Path(__file__).resolve().parent.parent
+    ap.add_argument("--dir", default=str(root / "plugin-repos"))
+    ap.add_argument("--plugin", help="only this plugin directory")
+    ap.add_argument("--all-hits", action="store_true",
+                    help="include low-signal hits (open/read/load on locals)")
+    args = ap.parse_args()
+
+    base = Path(args.dir)
+    if not base.is_dir():
+        sys.exit("not a directory: %s" % base)
+
+    plugins = [base / args.plugin] if args.plugin else sorted(
+        d for d in base.iterdir() if d.is_dir())
+
+    total = 0
+    for plugin in plugins:
+        rows = []
+        for src in sorted(plugin.glob("*.py")):
+            if src.name.startswith("test_"):
+                continue
+            for path, (name, s_base, why, lineno) in audit_file(src):
+                signal = any(h in s_base.lower() for h in HIGH_SIGNAL)
+                if not signal and not args.all_hits:
+                    continue
+                rows.append((src.name, lineno, "->".join(path),
+                             ("%s.%s" % (s_base, name)) if s_base else name, why))
+        if rows:
+            total += len(rows)
+            print("\n%s" % plugin.name)
+            for fname, lineno, chain, call, why in sorted(rows):
+                print("  %s:%-5d %-34s via %s" % (fname, lineno, call + "  (" + why + ")", chain))
+
+    print("\n%d blocking call(s) reachable from display() across %d plugin(s)"
+          % (total, len(plugins)))
+    print("Heuristic: a hit guarded by an interval check may be fine. Look, do "
+          "not assume.")
+
+
+if __name__ == "__main__":
+    main()

scripts/build_rgbmatrix_nogil.sh

@@ -0,0 +1,330 @@
+#!/usr/bin/env bash
+#
+# Rebuild the rgbmatrix Python binding so it releases the GIL.
+#
+# WHY THIS EXISTS
+# ---------------
+# The upstream binding declares FrameCanvas::SwapOnVSync WITHOUT `nogil`
+# (cppinc.pxd), unlike SetPixel/Clear/Fill on the lines just above it.
+# SwapOnVSync blocks until the panel's next vertical sync -- up to a full
+# refresh period on every frame -- so the render thread was holding the GIL
+# for most of every frame. Background threads (API fetches, JSON parsing,
+# image decode) were starved into long uninterruptible bursts, which in turn
+# made the render loop miss refreshes.
+#
+# Measured on a Pi 4 driving a 2x128x64 chain at limit_refresh_rate_hz=100:
+#
+#     before   ~44 fps average, 14-17% of frames 41-53ms
+#     after    100 fps, median 10.00ms, p95 10.05ms, 0% stalls
+#
+# The per-pixel blit (SetPixelsPillow) can also release the GIL and walk the
+# Pillow buffer row-major, but that is OFF by default and you almost certainly
+# want to leave it that way. Row-major changes what a partially-written frame
+# looks like: column-major tearing shows as a vertical seam, row-major tearing
+# shows as a horizontal split between the panel's upper and lower halves. On a
+# 1/32 scan panel that reads as a one-pixel "fold" across the middle of every
+# panel -- reported on hardware, and it went away when the blit was reverted.
+# Enable with RGB_PATCH_BLIT=1 only if you have measured that you need it;
+# essentially all of the gain above comes from the SwapOnVSync change alone.
+#
+# SAFETY
+# ------
+# Builds into a scratch directory; touches the installed module only in the
+# --install step, and backs up the original first. Roll back at any time with:
+#
+#     sudo bash scripts/build_rgbmatrix_nogil.sh --rollback
+#
+# USAGE
+#     bash scripts/build_rgbmatrix_nogil.sh              # build only
+#     sudo bash scripts/build_rgbmatrix_nogil.sh --install
+#     sudo bash scripts/build_rgbmatrix_nogil.sh --rollback
+#
+set -uo pipefail
+
+# Resolve the invoking user's home, not root's. --install runs under sudo,
+# where $HOME is /root, so every default path below pointed somewhere the
+# build had never written and the install died with "no built module found".
+if [ -n "${SUDO_USER:-}" ]; then
+    OWNER_HOME="$(getent passwd "$SUDO_USER" | cut -d: -f6)"
+fi
+OWNER_HOME="${OWNER_HOME:-$HOME}"
+
+SRC_TREE="${RGB_SRC_TREE:-$OWNER_HOME/LEDMatrix/rpi-rgb-led-matrix-master}"
+BUILD_DIR="${RGB_BUILD_DIR:-$OWNER_HOME/rgbmatrix-nogil-build}"
+VENV="${RGB_CYTHON_VENV:-$OWNER_HOME/.cache/ledmatrix-cython}"
+BACKUP="${RGB_BACKUP:-$OWNER_HOME/rgbmatrix-core.so.ORIGINAL}"
+PATCH_BLIT="${RGB_PATCH_BLIT:-0}"
+
+die() { echo "FATAL: $*" >&2; exit 1; }
+
+# This script runs under `set -uo pipefail` -- no -e -- so an unchecked
+# systemctl failure is silently ignored. That matters most for `stop`: leaving
+# the old service running means cp overwrites a module the running process has
+# mapped, the following `start` succeeds as a no-op, and the health check sees
+# an active unit and reports SUCCESS for a binding that was never loaded.
+# A machine with no ledmatrix.service at all is a normal build host, so that
+# case is skipped rather than treated as a failure.
+service_present() { systemctl cat ledmatrix.service >/dev/null 2>&1; }
+
+service_do() {
+    local verb="$1"
+    if ! service_present; then
+        echo "   (no ledmatrix.service installed - skipping $verb)"
+        return 0
+    fi
+    systemctl "$verb" ledmatrix || die "systemctl $verb ledmatrix failed"
+}
+
+py_site() {
+    python3 -c 'import rgbmatrix, os; print(os.path.dirname(rgbmatrix.__file__))' 2>/dev/null
+}
+
+# The extension filename the interpreter that builds -- and then loads -- this
+# module actually uses, e.g. core.cpython-313-aarch64-linux-gnu.so. The build
+# venv is made with --system-site-packages from python3, so the two agree;
+# falling back keeps --install working when the venv has been cleaned up.
+abi_name() {
+    local py="$VENV/bin/python"
+    [ -x "$py" ] || py=python3
+    "$py" -c \
+        'import sysconfig; print("core" + sysconfig.get_config_var("EXT_SUFFIX"))' \
+        2>/dev/null
+}
+
+# Exactly the current interpreter's artifact, never merely the first one that
+# sorts. Staging copies $SRC_TREE wholesale, so a core.cpython-*.so left in the
+# source tree by an earlier build comes along for the ride; build_ext --inplace
+# only ever overwrites the current ABI's name, and a glob piped to `head -1`
+# sorts cpython-311 ahead of cpython-313. That installed a stale, unpatched
+# module as core.so while the GIL check below -- which reads the freshly
+# generated core.cpp, not the .so -- still reported success.
+abi_so() {
+    local name path
+    name="$(abi_name)" || return 1
+    [ -n "$name" ] || return 1
+    path="$BUILD_DIR/bindings/python/rgbmatrix/$name"
+    [ -f "$path" ] || return 1
+    printf '%s\n' "$path"
+}
+
+do_rollback() {
+    local dst; dst="$(py_site)"
+    [ -n "$dst" ] || die "could not locate the installed rgbmatrix package"
+    [ -f "$BACKUP" ] || die "no backup at $BACKUP"
+    service_do stop
+    cp -a "$BACKUP" "$dst/core.so" || die "restore failed"
+    find "$dst" -name __pycache__ -type d -exec rm -rf {} + 2>/dev/null
+    service_do start
+    echo "rolled back to the original core.so"
+    exit 0
+}
+
+do_install() {
+    local so dst
+    so="$(abi_so)"; [ -n "$so" ] || die "no built module found - run the build first"
+    dst="$(py_site)"; [ -n "$dst" ] || die "could not locate the installed rgbmatrix package"
+
+    if [ ! -f "$BACKUP" ]; then
+        cp -a "$dst/core.so" "$BACKUP" || die "could not back up the original"
+        echo "backed up original core.so -> $BACKUP"
+    else
+        echo "backup already present at $BACKUP (keeping the true original)"
+    fi
+
+    service_do stop
+    cp "$so" "$dst/core.so" || die "install failed"
+    find "$dst" -name __pycache__ -type d -exec rm -rf {} + 2>/dev/null
+    service_do start
+
+    echo "waiting 25s for the display to come back..."
+    sleep 25
+    local healthy=1
+    systemctl is-active --quiet ledmatrix || healthy=0
+    if journalctl -u ledmatrix --since "40 sec ago" --no-pager \
+         | grep -qiE "Traceback|ImportError|Segmentation fault|undefined symbol"; then
+        healthy=0
+    fi
+    if [ "$healthy" = "1" ]; then
+        echo "SUCCESS - running on the rebuilt binding"
+    else
+        echo "UNHEALTHY - rolling back"
+        cp -a "$BACKUP" "$dst/core.so" \
+            || echo "ROLLBACK FAILED: could not restore $BACKUP -> $dst/core.so" >&2
+        if service_present && ! systemctl restart ledmatrix; then
+            echo "ROLLBACK FAILED: ledmatrix did not restart - the display is" \
+                 "down; restore manually with 'sudo bash $0 --rollback'" >&2
+        fi
+        journalctl -u ledmatrix --since "90 sec ago" --no-pager | tail -25
+        exit 1
+    fi
+    exit 0
+}
+
+case "${1:-}" in
+    --rollback) do_rollback ;;
+    --install)  do_install ;;
+    "" )        ;;
+    *)          die "unknown option: $1" ;;
+esac
+
+# ---------------------------------------------------------------- build ----
+[ -d "$SRC_TREE" ] || die "matrix source tree not found at $SRC_TREE (set RGB_SRC_TREE)"
+command -v g++ >/dev/null || die "g++ not installed (apt install build-essential)"
+
+echo "==> staging a scratch copy at $BUILD_DIR"
+rm -rf "$BUILD_DIR"
+cp -r "$SRC_TREE" "$BUILD_DIR" || die "copy failed"
+
+# Drop any extension artifacts that came across from the source tree. Nothing
+# downstream should be able to pick one up, and build_ext --inplace can decide
+# a copied .so is already up to date and skip the compile entirely.
+find "$BUILD_DIR/bindings/python/rgbmatrix" -maxdepth 1 \
+     -name 'core*.so' -delete 2>/dev/null
+
+echo "==> patching the bindings to release the GIL"
+python3 - "$BUILD_DIR" "$PATCH_BLIT" <<'PYEOF' || die "patch failed"
+import io
+import sys
+
+base = sys.argv[1] + "/bindings/python/rgbmatrix/"
+patch_blit = len(sys.argv) > 2 and sys.argv[2] == "1"
+
+# --- declare SwapOnVSync as nogil ---------------------------------------
+p = base + "cppinc.pxd"
+s = io.open(p, encoding="utf-8").read()
+OLD_DECL = "        FrameCanvas *SwapOnVSync(FrameCanvas*, uint8_t)\n"
+NEW_DECL = "        FrameCanvas *SwapOnVSync(FrameCanvas*, uint8_t) nogil\n"
+if OLD_DECL in s:
+    io.open(p, "w", encoding="utf-8", newline="\n").write(s.replace(OLD_DECL, NEW_DECL, 1))
+    print("   cppinc.pxd: SwapOnVSync declared nogil")
+elif NEW_DECL in s:
+    print("   cppinc.pxd: already nogil")
+else:
+    sys.exit("could not find the SwapOnVSync declaration")
+
+# --- release the GIL across the vsync wait ------------------------------
+p = base + "core.pyx"
+s = io.open(p, encoding="utf-8").read()
+
+OLD_SWAP = (
+    "    def SwapOnVSync(self, FrameCanvas newFrame, uint8_t framerate_fraction = 1):\n"
+    "        return __createFrameCanvas("
+    "self.__matrix.SwapOnVSync(newFrame.__canvas, framerate_fraction))\n"
+)
+NEW_SWAP = (
+    "    def SwapOnVSync(self, FrameCanvas newFrame, uint8_t framerate_fraction = 1):\n"
+    "        # Blocks until the panel's next vertical sync. Holding the GIL\n"
+    "        # across that wait starves every other Python thread for most of\n"
+    "        # each frame. Pointers are hoisted into C locals so the blocking\n"
+    "        # call itself needs no Python state.\n"
+    "        cdef cppinc.RGBMatrix* matrix = self.__matrix\n"
+    "        cdef cppinc.FrameCanvas* frame = newFrame.__canvas\n"
+    "        cdef uint8_t fraction = framerate_fraction\n"
+    "        cdef cppinc.FrameCanvas* swapped\n"
+    "        with nogil:\n"
+    "            swapped = matrix.SwapOnVSync(frame, fraction)\n"
+    "        return __createFrameCanvas(swapped)\n"
+)
+if OLD_SWAP in s:
+    s = s.replace(OLD_SWAP, NEW_SWAP, 1)
+    print("   core.pyx: SwapOnVSync releases the GIL")
+elif "swapped = matrix.SwapOnVSync(frame, fraction)" in s:
+    print("   core.pyx: SwapOnVSync already patched")
+else:
+    sys.exit("could not find the SwapOnVSync body")
+
+# --- optional: release the GIL across the blit --------------------------
+OLD_BLIT = (
+    "        buffer = get_pillow_buffer(image_capsule)\n"
+    "\n"
+    "        for col in range(max(0, -xstart), min(width, frame_width - xstart)):\n"
+    "            for row in range(max(0, -ystart), min(height, frame_height - ystart)):\n"
+    "                pixel = buffer[row][col]\n"
+    "                r = (pixel ) & 0xFF\n"
+    "                g = (pixel >> 8) & 0xFF\n"
+    "                b = (pixel >> 16) & 0xFF\n"
+    "                my_canvas.SetPixel(xstart+col, ystart+row, r, g, b)\n"
+)
+NEW_BLIT = (
+    "        buffer = get_pillow_buffer(image_capsule)\n"
+    "\n"
+    "        # Bounds hoisted so the blit needs no Python state and can run\n"
+    "        # without the GIL: it touches only a C buffer and a C++ canvas.\n"
+    "        # NOTE: row-major order makes a torn frame show as a horizontal\n"
+    "        # split across the panel's halves. See the header before enabling.\n"
+    "        cdef int col_start = max(0, -xstart)\n"
+    "        cdef int col_end = min(width, frame_width - xstart)\n"
+    "        cdef int row_start = max(0, -ystart)\n"
+    "        cdef int row_end = min(height, frame_height - ystart)\n"
+    "\n"
+    "        with nogil:\n"
+    "            for row in range(row_start, row_end):\n"
+    "                for col in range(col_start, col_end):\n"
+    "                    pixel = buffer[row][col]\n"
+    "                    r = (pixel ) & 0xFF\n"
+    "                    g = (pixel >> 8) & 0xFF\n"
+    "                    b = (pixel >> 16) & 0xFF\n"
+    "                    my_canvas.SetPixel(xstart+col, ystart+row, r, g, b)\n"
+)
+if patch_blit:
+    if OLD_BLIT in s:
+        s = s.replace(OLD_BLIT, NEW_BLIT, 1)
+        print("   core.pyx: pixel blit releases the GIL, row-major")
+    elif "for row in range(row_start, row_end):" in s:
+        print("   core.pyx: blit already patched")
+    else:
+        sys.exit("could not find the SetPixelsPillow loop")
+else:
+    print("   core.pyx: blit left unpatched (RGB_PATCH_BLIT=1 to enable)")
+
+io.open(p, "w", encoding="utf-8", newline="\n").write(s)
+PYEOF
+
+echo "==> building librgbmatrix.a (this takes a few minutes)"
+nice -n 10 make -C "$BUILD_DIR/lib" -j2 >/dev/null 2>&1 \
+    || die "library build failed - rerun 'make -C $BUILD_DIR/lib' to see why"
+[ -f "$BUILD_DIR/lib/librgbmatrix.a" ] || die "librgbmatrix.a was not produced"
+
+echo "==> preparing Cython"
+[ -d "$VENV" ] || python3 -m venv --system-site-packages "$VENV" || die "venv failed"
+"$VENV/bin/pip" install --quiet cython || die "cython install failed"
+
+cat > "$BUILD_DIR/bindings/python/setup.py" <<'EOF'
+from setuptools import setup, Extension
+from Cython.Build import cythonize
+
+core = Extension(
+    "rgbmatrix.core",
+    sources=["rgbmatrix/core.pyx", "rgbmatrix/shims/pillow.c"],
+    include_dirs=["../../include", "rgbmatrix/shims"],
+    extra_objects=["../../lib/librgbmatrix.a"],
+    language="c++",
+    extra_compile_args=["-O3", "-Wall", "-fno-exceptions", "-std=c++11"],
+    extra_link_args=["-lrt", "-lm", "-lpthread"],
+)
+
+setup(name="rgbmatrix",
+      ext_modules=cythonize([core], language_level="3str",
+                            compiler_directives={"binding": False}))
+EOF
+
+echo "==> compiling the extension"
+( cd "$BUILD_DIR/bindings/python" && "$VENV/bin/python" setup.py build_ext --inplace ) \
+    >/dev/null 2>&1 || die "extension build failed"
+
+SO="$(abi_so)" || true
+[ -n "$SO" ] || die "no .so produced - expected $(abi_name) in $BUILD_DIR/bindings/python/rgbmatrix"
+
+# Verify the GIL really is released before anyone installs this.
+EXPECTED=1; [ "$PATCH_BLIT" = "1" ] && EXPECTED=2
+PAIRS=$(grep -c "PyEval_SaveThread\|Py_UNBLOCK_THREADS" \
+        "$BUILD_DIR/bindings/python/rgbmatrix/core.cpp")
+[ "$PAIRS" -ge "$EXPECTED" ] \
+    || die "generated C++ has $PAIRS GIL-release sites, expected >= $EXPECTED"
+
+echo
+echo "BUILT: $SO"
+echo "       ($PAIRS GIL-release site(s) in the generated C++)"
+echo
+echo "Install with:   sudo bash $0 --install"
+echo "Roll back with: sudo bash $0 --rollback"

scripts/run_plugin_tests.py

@@ -6,6 +6,9 @@ Discovers and runs tests for LEDMatrix plugins.
 Supports both unittest and pytest.
 """
 
+import os
+import re
+import subprocess  # nosec B404 - list-form argv only, no shell  # nosemgrep
 import sys
 import argparse
 from pathlib import Path
@@ -68,6 +71,79 @@ def _find_tests_in_dir(directory: Path) -> list:
     return sorted(set(test_files))
 
 
+def _is_script_style(path) -> bool:
+    """True when a test file is a standalone script, not a pytest module.
+
+    Most plugin tests are written as `def main()` plus an `if __name__ ==
+    "__main__"` guard and signal through an exit code. pytest collects zero
+    items from those, so handing them to pytest printed "no tests ran" and this
+    runner reported success over work it had not done -- 151 of 248 files on a
+    fully populated rig.
+    """
+    try:
+        src = Path(path).read_text(encoding="utf-8", errors="replace")
+    except OSError:
+        return False
+    has_pytest_items = re.search(r"^\s*(def test_|class Test|async def test_)", src, re.M)
+    has_main_guard = "__main__" in src and "__name__" in src
+    return bool(has_main_guard and not has_pytest_items)
+
+
+def run_script_tests(test_files: list, verbose: bool = False) -> int:
+    """Run standalone test scripts, honouring the 0 pass / 2 skip / 1 fail
+    convention that ledmatrix-plugins' own runner established.
+
+    Scripts opt into skipping by printing "SKIP: <reason>" and exiting 2 --
+    a script that needs a tty or an LED matrix is not a regression.
+    """
+    env = dict(os.environ)
+    # Prepend rather than setdefault. An inherited PYTHONPATH -- a developer's
+    # shell, a tox run, another checkout -- otherwise wins outright, and the
+    # subprocess imports a different copy of the core than the one under test.
+    # That is exactly the failure ledmatrix-plugins#467 describes, and it is
+    # invisible: the tests pass or fail against a tree nobody meant to test.
+    inherited = env.get("PYTHONPATH")
+    env["PYTHONPATH"] = (f"{PROJECT_ROOT}{os.pathsep}{inherited}"
+                         if inherited else str(PROJECT_ROOT))
+    env["LEDMATRIX_CORE"] = str(PROJECT_ROOT)
+
+    passed = skipped = failed = 0
+    failures = []
+    for path in test_files:
+        try:
+            # Fixed interpreter (sys.executable) plus a test path this script
+            # discovered by globbing the repo; argument list, no shell, so
+            # nothing is word-split or expanded. Same suppression pair the
+            # rest of the repo uses for this shape (see permission_utils.py).
+            proc = subprocess.run(  # noqa: S603  # nosec B603 - no shell invoked (list-form argv)  # nosemgrep
+                [sys.executable, str(path)],  # nosemgrep
+                cwd=str(Path(path).parent),
+                capture_output=True, text=True, env=env,
+                stdin=subprocess.DEVNULL, timeout=300,
+            )
+            rc = proc.returncode
+            tail = " | ".join((proc.stdout or proc.stderr or "").strip().splitlines()[-2:])[:200]
+        except subprocess.TimeoutExpired:
+            rc, tail = 1, "timed out after 300s"
+        if rc == 0:
+            passed += 1
+            label = "pass"
+        elif rc == 2:
+            skipped += 1
+            label = "SKIP"
+        else:
+            failed += 1
+            label = "FAIL"
+            failures.append(f"{Path(path).name}: exit {rc} | {tail}")
+        if verbose or rc != 0:
+            print(f"  [{label}] {Path(path).name}" + (f" -- {tail}" if rc != 0 else ""))
+
+    print(f"\n{passed} passed, {skipped} skipped, {failed} failed (scripts)")
+    for f in failures:
+        print(f"  - {f}", file=sys.stderr)
+    return 1 if failed else 0
+
+
 def run_unittest_tests(test_files: list, verbose: bool = False) -> int:
     """
     Run tests using unittest.
@@ -186,7 +262,12 @@ def main():
             print("No test files found in plugins directory")
         return 0
     
-    print(f"Found {len(test_files)} test file(s)")
+    scripts = [f for f in test_files if _is_script_style(f)]
+    modules = [f for f in test_files if f not in scripts]
+
+    print(f"Found {len(test_files)} test file(s)"
+          + (f" -- {len(modules)} collectable, {len(scripts)} standalone script(s)"
+             if scripts else ""))
     for test_file in test_files:
         print(f"  - {test_file}")
     print()
@@ -200,11 +281,20 @@ def main():
         except ImportError:
             runner = 'unittest'
 
-    # Run tests
+    # Standalone scripts cannot be collected by pytest or unittest -- run them
+    # as the scripts they are. Doing this rather than silently collecting zero
+    # items is the whole point: this runner used to report success having
+    # executed nothing.
+    rc = 0
+    if scripts:
+        rc |= run_script_tests(scripts, args.verbose)
+
+    if modules:
         if runner == 'pytest':
-        return run_pytest_tests(test_files, args.verbose, args.coverage)
+            rc |= run_pytest_tests(modules, args.verbose, args.coverage)
         else:
-        return run_unittest_tests(test_files, args.verbose)
+            rc |= run_unittest_tests(modules, args.verbose)
+    return rc
 
 
 if __name__ == '__main__':

scripts/scroll_speeds.py

@@ -0,0 +1,238 @@
+#!/usr/bin/env python3
+"""Show and try the scroll speeds your panel can display cleanly.
+
+Motion looks smooth when the strip advances a WHOLE number of pixels per panel
+refresh. Anything else has to blend two columns (which on pixel-font text reads
+as shimmer) or repeat frames unevenly (which reads as judder). So the speeds
+worth using are not arbitrary -- they are
+
+    refresh_hz / frame_hold * pixels_per_frame
+
+for whole numbers of frame_hold and pixels_per_frame, and that ladder depends
+on how fast YOUR panel actually refreshes. A Pi Zero driving a big chain will
+have a completely different set of good speeds from a Pi 4 driving a small one.
+
+    # what can this panel do? (no hardware needed, uses your configured rate)
+    python3 scripts/scroll_speeds.py
+
+    # measure what the panel ACTUALLY manages, rather than what is configured
+    sudo systemctl stop ledmatrix
+    sudo python3 scripts/scroll_speeds.py --measure
+    sudo systemctl start ledmatrix
+
+    # what would a 60Hz panel offer?
+    python3 scripts/scroll_speeds.py --hz 60
+
+    # try one on the panel
+    sudo systemctl stop ledmatrix
+    sudo python3 scripts/scroll_speeds.py --demo 50
+    sudo systemctl start ledmatrix
+
+This script never starts or stops the display service itself -- that is left to
+you, so a crash here can never leave the panel dark.
+"""
+from __future__ import annotations
+
+import argparse
+import json
+import os
+import sys
+import time
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from src.common import scroll_config  # noqa: E402
+
+CONFIG = Path(__file__).resolve().parent.parent / "config" / "config.json"
+
+
+def load_hardware():
+    try:
+        with open(CONFIG, encoding="utf-8") as handle:
+            return (json.load(handle).get("display") or {}).get("hardware") or {}
+    except (OSError, ValueError):
+        return {}
+
+
+def build_options(hardware, refresh_override=None):
+    from rgbmatrix import RGBMatrixOptions
+
+    o = RGBMatrixOptions()
+    o.rows = int(hardware.get("rows", 32))
+    o.cols = int(hardware.get("cols", 64))
+    o.chain_length = int(hardware.get("chain_length", 1))
+    o.parallel = int(hardware.get("parallel", 1))
+    o.brightness = int(hardware.get("brightness", 80))
+    o.hardware_mapping = hardware.get("hardware_mapping", "regular")
+    o.pwm_bits = int(hardware.get("pwm_bits", 11))
+    o.pwm_dither_bits = int(hardware.get("pwm_dither_bits", 0))
+    o.pwm_lsb_nanoseconds = int(hardware.get("pwm_lsb_nanoseconds", 130))
+    o.led_rgb_sequence = hardware.get("led_rgb_sequence", "RGB")
+    o.scan_mode = int(hardware.get("scan_mode", 0))
+    o.row_address_type = int(hardware.get("row_address_type", 0))
+    o.multiplexing = int(hardware.get("multiplexing", 0))
+    o.gpio_slowdown = int(hardware.get("gpio_slowdown", 2))
+    o.limit_refresh_rate_hz = (
+        int(refresh_override) if refresh_override is not None
+        else int(hardware.get("limit_refresh_rate_hz", 0))
+    )
+    return o
+
+
+def open_matrix(hardware, refresh_override=None):
+    """Construct the matrix, or explain why it will not open."""
+    if os.geteuid() != 0:
+        sys.exit("this needs root for GPIO access - rerun with sudo")
+    try:
+        from rgbmatrix import RGBMatrix
+    except ImportError:
+        sys.exit("rgbmatrix is not installed on this machine")
+    try:
+        return RGBMatrix(options=build_options(hardware, refresh_override))
+    except Exception as exc:  # pragma: no cover - hardware dependent
+        sys.exit(
+            "could not open the panel ({}).\n"
+            "If the display service is running it owns the GPIO - stop it first:\n"
+            "    sudo systemctl stop ledmatrix".format(exc)
+        )
+
+
+def measure_refresh(hardware, seconds=6.0):
+    """Actual refresh rate, by running uncapped and timing the swaps.
+
+    SwapOnVSync blocks until the panel's next refresh, so an unthrottled loop
+    runs at exactly the panel's rate. This is what an older Pi or a longer
+    chain will really give you, as opposed to whatever limit_refresh_rate_hz
+    optimistically asks for.
+    """
+    matrix = open_matrix(hardware, refresh_override=0)
+    canvas = matrix.CreateFrameCanvas()
+    canvas = matrix.SwapOnVSync(canvas)  # discard the first, it includes setup
+    frames = 0
+    started = time.perf_counter()
+    while time.perf_counter() - started < seconds:
+        canvas = matrix.SwapOnVSync(canvas)
+        frames += 1
+    measured = frames / (time.perf_counter() - started)
+    matrix.Clear()
+    return measured
+
+
+def demo(hardware, target, seconds):
+    """Scroll text at the crisp speed nearest `target`."""
+    from PIL import Image, ImageDraw, ImageFont
+
+    hz = float(hardware.get("limit_refresh_rate_hz") or scroll_config.DEFAULT_REFRESH_HZ)
+    choice = scroll_config.solve_crisp(target, hz)
+    print("asked for {:.0f} px/s -> {}".format(target, choice.describe()))
+
+    matrix = open_matrix(hardware)
+    canvas = matrix.CreateFrameCanvas()
+    W, H = canvas.width, canvas.height
+
+    font = None
+    for path, size in (
+        (str(Path(__file__).resolve().parent.parent / "assets/fonts/PressStart2P-Regular.ttf"), 16),
+        ("/usr/share/fonts/truetype/dejavu/DejaVuSansMono-Bold.ttf", 26),
+    ):
+        try:
+            font = ImageFont.truetype(path, size)
+            break
+        except OSError:
+            continue
+    if font is None:
+        font = ImageFont.load_default()
+
+    text = "  {:.0f} px/s  ***  THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG  ***".format(
+        choice.pixels_per_second)
+    box = ImageDraw.Draw(Image.new("RGB", (8, 8))).textbbox((0, 0), text, font=font)
+    tw, th = box[2] - box[0], box[3] - box[1]
+    reps = max(2, (W * 3) // max(tw, 1) + 1)
+    strip = Image.new("RGB", (tw * reps, H), (0, 0, 0))
+    draw = ImageDraw.Draw(strip)
+    for i in range(reps):
+        draw.text((i * tw, (H - th) // 2 - box[1]), text, font=font, fill=(255, 210, 60))
+
+    offset = 0
+    frames = 0
+    started = time.time()
+    while time.time() - started < seconds:
+        window = strip.crop((offset, 0, offset + W, H))
+        if window.width < W:
+            whole = Image.new("RGB", (W, H), (0, 0, 0))
+            head = strip.crop((offset, 0, strip.width, H))
+            whole.paste(head, (0, 0))
+            whole.paste(strip.crop((0, 0, W - head.width, H)), (head.width, 0))
+            window = whole
+        canvas.SetImage(window)
+        canvas = matrix.SwapOnVSync(canvas, choice.frame_hold)
+        offset = (offset + choice.pixels_per_frame) % strip.width
+        frames += 1
+    elapsed = time.time() - started
+    print("  {} frames in {:.1f}s = {:.1f} fps = {:.1f} px/s actual".format(
+        frames, elapsed, frames / elapsed, frames * choice.pixels_per_frame / elapsed))
+    matrix.Clear()
+
+
+def print_ladder(hz, highlight=None):
+    print("")
+    print("Whole-pixel scroll speeds at {:.1f}Hz refresh".format(hz))
+    print("(the panel refreshes at {:.0f}Hz for every one of these - holding a "
+          "frame costs no flicker)".format(hz))
+    print("")
+    for entry in scroll_config.crisp_ladder(hz):
+        if entry.pixels_per_second > hz * 3:
+            break
+        mark = " <-- nearest to {:.0f}".format(highlight) if (
+            highlight is not None
+            and entry.pixels_per_second == scroll_config.solve_crisp(highlight, hz).pixels_per_second
+        ) else ""
+        print("  " + entry.describe() + mark)
+    print("")
+    print("Set one in config.json as pixels per second, e.g.")
+    print('  "display_options": {{"scroll_pixels_per_second": {:.0f}}}'.format(
+        scroll_config.solve_crisp(highlight if highlight else hz / 2, hz).pixels_per_second))
+
+
+def main():
+    ap = argparse.ArgumentParser(description=__doc__,
+                                 formatter_class=argparse.RawDescriptionHelpFormatter)
+    ap.add_argument("--hz", type=float,
+                    help="refresh rate to compute the ladder for (default: your config)")
+    ap.add_argument("--measure", action="store_true",
+                    help="measure the panel's real refresh rate (needs root, service stopped)")
+    ap.add_argument("--demo", type=float, metavar="PXPS",
+                    help="scroll text at the crisp speed nearest this (needs root)")
+    ap.add_argument("--seconds", type=float, default=15.0, help="demo duration")
+    ap.add_argument("--want", type=float, metavar="PXPS",
+                    help="highlight the entry nearest this speed")
+    args = ap.parse_args()
+
+    hardware = load_hardware()
+    configured = float(hardware.get("limit_refresh_rate_hz") or 0)
+
+    if args.demo is not None:
+        demo(hardware, args.demo, args.seconds)
+        return
+
+    if args.measure:
+        measured = measure_refresh(hardware)
+        print("measured panel refresh: {:.1f}Hz".format(measured))
+        if configured:
+            print("configured limit_refresh_rate_hz: {:.0f}".format(configured))
+            if measured < configured * 0.95:
+                print("  -> the panel cannot reach the configured rate; the ladder")
+                print("     below uses what it actually manages")
+        print_ladder(measured, args.want)
+        return
+
+    hz = args.hz or configured or scroll_config.DEFAULT_REFRESH_HZ
+    if not args.hz and not configured:
+        print("no limit_refresh_rate_hz in config; assuming {:.0f}Hz".format(hz))
+        print("run with --measure to find your panel's real rate")
+    print_ladder(hz, args.want)
+
+
+if __name__ == "__main__":
+    main()

src/cache/disk_cache.py

@@ -5,6 +5,7 @@ Handles persistent disk-based caching with atomic writes and error recovery.
 """
 
 import json
+import math
 import os
 import time
 import tempfile
@@ -14,6 +15,11 @@ import zlib
 from typing import Dict, Any, Optional, Protocol
 from datetime import datetime
 
+try:  # optional: large speedup on the cache write path, see _dumps below
+    import orjson
+except ImportError:  # pragma: no cover - exercised on hosts without the wheel
+    orjson = None
+
 # How old an abandoned write's temp file must be before the sweep removes it.
 # A real write holds its temp file for milliseconds, so an hour is far beyond
 # any in-flight write while still clearing the same day's debris. Deliberately
@@ -40,13 +46,97 @@ class CacheStrategyProtocol(Protocol):
 
 
 class DateTimeEncoder(json.JSONEncoder):
-    """JSON encoder that handles datetime objects."""
+    """JSON encoder that handles datetime objects.
+
+    Retained for the stdlib fallback path and for any caller importing it.
+    """
     def default(self, obj: Any) -> Any:
         if isinstance(obj, datetime):
             return obj.isoformat()
         return super().default(obj)
 
 
+def _datetime_default(obj: Any) -> Any:
+    """Serialise datetimes exactly as DateTimeEncoder did."""
+    if isinstance(obj, datetime):
+        return obj.isoformat()
+    raise TypeError(f"Object of type {type(obj).__name__} is not JSON serializable")
+
+
+def _replace_nonfinite(obj: Any) -> Any:
+    """Non-finite floats -> None, matching what ``orjson.dumps`` writes.
+
+    Only reached once a strict pass has proved there is something to replace,
+    so the ordinary write path never pays for this walk.
+    """
+    if isinstance(obj, float):
+        return obj if math.isfinite(obj) else None
+    if isinstance(obj, dict):
+        return {k: _replace_nonfinite(v) for k, v in obj.items()}
+    if isinstance(obj, (list, tuple)):
+        return [_replace_nonfinite(v) for v in obj]
+    return obj
+
+
+# NON-FINITE FLOATS
+# -----------------
+# JSON has no NaN or Infinity. The stdlib emits them anyway as an extension;
+# orjson refuses to and writes null. That divergence is not acceptable in a
+# cache whose files outlive the decision of which encoder is installed, so the
+# policy here is one behaviour on both paths:
+#
+#   writing  non-finite floats become null, whichever encoder is in use
+#   reading  files already on disk that carry the stdlib's NaN/Infinity
+#            tokens stay readable, whichever encoder is in use
+#
+# Without the write half, installing orjson silently changed cached values.
+# Without the read half, installing orjson turned every legacy record holding a
+# NaN into a "corrupted cache file" that DiskCache.get logged as an error and
+# deleted. Both halves are covered by test/test_cache_nonfinite_floats.py.
+
+
+if orjson is not None:
+    # Encoding the cache record dominated the background fetch worker: on a
+    # Pi 4, stdlib json.dumps runs ~12ms per MB and holds the GIL for all of
+    # it, which stalls the render thread mid-scroll. orjson measures ~7x
+    # faster on the same payloads (11.9ms -> 1.6ms for 985KB). Decoding gains
+    # far less (~1.3x on large payloads) because the cost there is building
+    # the Python objects, not scanning the text, but it is still free to take.
+    #
+    # OPT_NON_STR_KEYS: stdlib json coerces int/float dict keys to strings;
+    # orjson raises without this, and cache records do carry numeric keys.
+    # OPT_PASSTHROUGH_DATETIME: orjson would otherwise emit its own RFC 3339
+    # form for datetimes instead of calling default(). Routing them through
+    # _datetime_default keeps byte-for-byte parity with the records already
+    # on disk.
+    _DUMPS_OPTS = orjson.OPT_NON_STR_KEYS | orjson.OPT_PASSTHROUGH_DATETIME
+
+    def _dumps(data: Any) -> bytes:
+        return orjson.dumps(data, default=_datetime_default, option=_DUMPS_OPTS)
+
+    def _loads(raw: bytes) -> Any:
+        try:
+            return orjson.loads(raw)
+        except orjson.JSONDecodeError:
+            # Legacy record written by the stdlib path, carrying NaN or
+            # Infinity. Genuinely malformed files raise again from here, as
+            # json.JSONDecodeError, which is what DiskCache.get expects.
+            return json.loads(raw)
+else:
+    def _dumps(data: Any) -> bytes:
+        try:
+            return json.dumps(data, cls=DateTimeEncoder,
+                              allow_nan=False).encode("utf-8")
+        except ValueError:
+            # allow_nan=False is what detects the non-finite values; the walk
+            # runs only now that we know there is one to replace.
+            return json.dumps(_replace_nonfinite(data), cls=DateTimeEncoder,
+                              allow_nan=False).encode("utf-8")
+
+    def _loads(raw: bytes) -> Any:
+        return json.loads(raw)
+
+
 class DiskCache:
     """Manages persistent disk-based cache."""
     
@@ -99,8 +189,8 @@ class DiskCache:
         
         try:
             with self._lock:
-                with open(cache_path, 'r', encoding='utf-8') as f:
-                    record = json.load(f)
+                with open(cache_path, 'rb') as f:
+                    record = _loads(f.read())
             
             # Determine record timestamp (prefer embedded, else file mtime)
             record_ts = None
@@ -189,12 +279,12 @@ class DiskCache:
         # write path below, and cache files are machine-read only — indenting
         # them just multiplied the bytes written to the SD card.
         try:
-            payload = json.dumps(data, cls=DateTimeEncoder)
+            payload = _dumps(data)
         except (TypeError, ValueError) as e:
             self.logger.warning("Cache data for key '%s' not serializable: %s", key, e)
             return
 
-        digest = zlib.adler32(payload.encode('utf-8'))
+        digest = zlib.adler32(payload)
 
         try:
             # Atomic write to avoid partial/corrupt files
@@ -242,7 +332,7 @@ class DiskCache:
                         # wear source (dozens of fsyncs/min on API-heavy
                         # installs) for data that can be re-downloaded.
                         try:
-                            with os.fdopen(fd, 'w', encoding='utf-8') as tmp_file:
+                            with os.fdopen(fd, 'wb') as tmp_file:
                                 tmp_file.write(payload)
                             os.replace(tmp_path, cache_path)
                             self._write_digests[key] = digest
@@ -260,7 +350,7 @@ class DiskCache:
                     else:
                         # Fallback: direct write (not atomic, but better than failing)
                         try:
-                            with open(cache_path, 'w', encoding='utf-8') as cache_file:
+                            with open(cache_path, 'wb') as cache_file:
                                 cache_file.write(payload)
                             self._write_digests[key] = digest
                             # Set proper permissions: 660 (rw-rw----) for group-readable cache files
@@ -290,7 +380,7 @@ class DiskCache:
                             # is a different path, so future sets must keep
                             # retrying the primary location.
                             fallback_path = os.path.join(fallback_dir, os.path.basename(cache_path))
-                            with open(fallback_path, 'w', encoding='utf-8') as tmp_file:
+                            with open(fallback_path, 'wb') as tmp_file:
                                 tmp_file.write(payload)
                             # Set proper permissions: 660 (rw-rw----) for group-readable cache files
                             try:

src/common/__init__.py

@@ -23,6 +23,13 @@ from src.common.error_handler import (
 )
 from src.common.api_helper import APIHelper
 from src.common.scroll_helper import ScrollHelper
+from src.common import scroll_config
+from src.common.scroll_config import (
+    ScrollSettings,
+    configure as configure_scroll,
+    resolve as resolve_scroll_settings,
+    refresh_hz_from_config,
+)
 from src.common.logo_helper import LogoHelper
 from src.common.text_helper import TextHelper
 
@@ -60,6 +67,11 @@ __all__ = [
     'log_and_raise',
     'APIHelper',
     'ScrollHelper',
+    'scroll_config',
+    'ScrollSettings',
+    'configure_scroll',
+    'resolve_scroll_settings',
+    'refresh_hz_from_config',
     'LogoHelper',
     'TextHelper',
     # adaptive layout & images

src/common/scroll_config.py

@@ -0,0 +1,440 @@
+"""One place that turns plugin config into a configured ScrollHelper.
+
+Five ticker plugins each hand-rolled this resolution (odds-ticker, news and
+ledmatrix-leaderboard reference the deprecated ``scroll_pixels_per_second``
+key 16-18 times apiece), and they disagreed in ways that were invisible until
+someone watched the panel:
+
+* odds-ticker read ``scroll_pixels_per_second`` on the *recommended* config
+  path and let it override ``scroll_speed``/``scroll_delay``. Because that key
+  carries a schema default, the documented settings were dead for every user
+  -- see ChuckBuilds/ledmatrix-plugins#408.
+* ledmatrix-leaderboard read the same key only as a fallback, so identical
+  config produced different speeds in the two plugins.
+* stock-news derived px/frame from it via its own arithmetic.
+
+What matters on the hardware
+----------------------------
+Motion is smooth when the strip advances a **whole number of pixels per panel
+refresh**. On a 100Hz panel that means 100 px/s, 200 px/s, and so on. Anything
+else has to either blend adjacent columns (which on pixel-font text reads as
+shimmer) or repeat frames (which reads as judder). :func:`resolve` warns when
+the requested speed will not divide evenly, because that is a real display
+artefact and not a rounding detail.
+
+Speed is always expressed to the helper as pixels per second and applied in
+time-based mode. Frame-based stepping gates motion on a wall clock at
+``1/scroll_delay`` steps per second; plugins set ``scroll_delay`` to the frame
+period, which puts that comparison exactly on its own threshold and makes the
+step count flip on sub-millisecond jitter. Accumulating elapsed time keeps
+position proportional to real time instead.
+"""
+
+from __future__ import annotations
+
+import logging
+from dataclasses import dataclass, replace
+from typing import Any, Dict, Optional
+
+logger = logging.getLogger(__name__)
+
+#: Speed used when a plugin supplies nothing usable. One pixel per refresh on a
+#: 100Hz panel, which is the slowest crisp scroll that hardware can show.
+DEFAULT_PIXELS_PER_SECOND = 100.0
+
+#: Bounds accepted from config. Below the floor a marquee appears frozen;
+#: above the ceiling it outruns any panel's refresh and tears.
+MIN_PIXELS_PER_SECOND = 1.0
+MAX_PIXELS_PER_SECOND = 500.0
+
+#: Assumed refresh when the caller does not say. Matches the usual
+#: ``display.hardware.limit_refresh_rate_hz``.
+DEFAULT_REFRESH_HZ = 100.0
+
+#: How far px/s may sit from a whole number of pixels per refresh before it is
+#: worth warning about. 0.05px per frame is invisible; a third of a pixel is not.
+_WHOLE_PIXEL_TOLERANCE = 0.05
+
+
+#: Longest a frame may be held before motion reads as a slideshow rather than
+#: a scroll. 6 refreshes at 100Hz is ~17px/s, already visibly stepped.
+MAX_FRAME_HOLD = 8
+
+#: Largest whole-pixel jump per presented frame before motion looks like it is
+#: teleporting rather than sliding.
+MAX_PIXELS_PER_FRAME = 6
+
+
+@dataclass(frozen=True)
+class CrispSpeed:
+    """A speed the panel can show with whole-pixel motion.
+
+    ``pixels_per_second`` is always ``refresh_hz / frame_hold * pixels_per_frame``
+    exactly -- no rounding, no fractional pixel positions, so nothing has to be
+    blended or repeated unevenly.
+
+    :param frame_hold: refreshes each frame is held for. This is rgbmatrix's
+        ``SwapOnVSync(canvas, framerate_fraction)``. The panel keeps refreshing
+        at full rate either way, so holding a frame costs nothing in flicker.
+    :param pixels_per_frame: whole pixels advanced per presented frame.
+    """
+
+    pixels_per_second: float
+    frame_hold: int
+    pixels_per_frame: int
+    refresh_hz: float
+
+    @property
+    def frames_per_second(self) -> float:
+        return self.refresh_hz / self.frame_hold
+
+    @property
+    def steppiness(self) -> str:
+        """Rough readability hint for this combination."""
+        if self.pixels_per_frame > 2:
+            return "jumpy"
+        if self.frames_per_second < 20:
+            return "stepped"
+        if self.frames_per_second < 30:
+            return "slightly stepped"
+        return "smooth"
+
+    def describe(self) -> str:
+        return (
+            f"{self.pixels_per_second:6.1f} px/s  "
+            f"({self.pixels_per_frame}px every {self.frame_hold} refresh"
+            f"{'es' if self.frame_hold != 1 else ' '} = "
+            f"{self.frames_per_second:5.1f} fps, {self.steppiness})"
+        )
+
+
+def crisp_ladder(
+    refresh_hz: float = DEFAULT_REFRESH_HZ,
+    max_frame_hold: int = MAX_FRAME_HOLD,
+    max_pixels_per_frame: int = MAX_PIXELS_PER_FRAME,
+):
+    """Every whole-pixel speed this panel can show, slowest first.
+
+    Duplicates are collapsed keeping the gentlest option: 100 px/s is reachable
+    as 1px every refresh or 2px every 2nd refresh, and the former moves in
+    smaller increments, so that is the one worth offering.
+    """
+    best = {}
+    for hold in range(1, max_frame_hold + 1):
+        for ppf in range(1, max_pixels_per_frame + 1):
+            pps = refresh_hz / hold * ppf
+            key = round(pps, 3)
+            candidate = CrispSpeed(pps, hold, ppf, refresh_hz)
+            incumbent = best.get(key)
+            if incumbent is None or ppf < incumbent.pixels_per_frame:
+                best[key] = candidate
+    return [best[k] for k in sorted(best)]
+
+
+#: How much a bigger pixel step costs, as a fraction of the target speed.
+#: Tuned so 66.7px/s (2px at 33fps) beats 50px/s (1px at 50fps) when 60 was
+#: asked for, but 33.3px/s (1px, smooth) still beats 28.6px/s (2px at 14fps)
+#: when 30 was asked for -- being 11% slow is worth far less than looking bad.
+_STEP_PENALTY = 0.05
+_SLOW_FPS_PENALTY = 0.25   # below 20fps
+_LOWISH_FPS_PENALTY = 0.10  # below 25fps
+
+
+def _quality_cost(candidate: "CrispSpeed", target: float) -> float:
+    """Lower is better. Numeric closeness alone picks bad-looking speeds.
+
+    Nearest-by-value would answer "30 px/s" with 28.6 px/s -- which is 2px
+    jumps at 14fps -- over 33.3 px/s, which is single-pixel motion at 33fps and
+    obviously better on the panel. Proximity has to be traded against how the
+    motion actually reads.
+    """
+    error = abs(candidate.pixels_per_second - target) / max(target, 1e-6)
+    cost = error + _STEP_PENALTY * (candidate.pixels_per_frame - 1)
+    fps = candidate.frames_per_second
+    if fps < 20:
+        cost += _SLOW_FPS_PENALTY
+    elif fps < 25:
+        cost += _LOWISH_FPS_PENALTY
+    return cost
+
+
+def solve_crisp(
+    target_pixels_per_second: float,
+    refresh_hz: float = DEFAULT_REFRESH_HZ,
+    max_frame_hold: int = MAX_FRAME_HOLD,
+    max_pixels_per_frame: int = MAX_PIXELS_PER_FRAME,
+) -> CrispSpeed:
+    """The whole-pixel speed that will look best for what was asked for.
+
+    Not simply the nearest -- see :func:`_quality_cost`. Ties break toward the
+    smaller pixel step and the shorter hold.
+    """
+    ladder = crisp_ladder(refresh_hz, max_frame_hold, max_pixels_per_frame)
+    # Clamp into the ladder's range first. Relative error saturates near 1.0
+    # for a target far outside it, so the quality penalty would dominate and
+    # answer "10000 px/s" with the *slowest* entry -- smooth, and useless.
+    target = min(max(target_pixels_per_second, ladder[0].pixels_per_second),
+                 ladder[-1].pixels_per_second)
+    return min(
+        ladder,
+        key=lambda c: (round(_quality_cost(c, target), 6),
+                       c.pixels_per_frame, c.frame_hold),
+    )
+
+
+@dataclass(frozen=True)
+class ScrollSettings:
+    """The resolved outcome, and which config key produced it."""
+
+    pixels_per_second: float
+    source: str
+    target_fps: Optional[float] = None
+    pixels_per_frame: Optional[float] = None
+    warning: Optional[str] = None
+    #: The whole-pixel speed actually applied, when snapping was enabled.
+    crisp: Optional[CrispSpeed] = None
+    #: What the config asked for, before snapping.
+    requested_pixels_per_second: Optional[float] = None
+
+    @property
+    def frame_hold(self) -> int:
+        """Refreshes to hold each frame for; pass to set_scrolling_state()."""
+        return self.crisp.frame_hold if self.crisp else 1
+
+    def describe(self) -> str:
+        text = f"{self.pixels_per_second:.1f} px/s (from {self.source})"
+        if self.pixels_per_frame is not None:
+            text += f" = {self.pixels_per_frame:.2f} px/frame"
+        if self.target_fps:
+            text += f" at {self.target_fps:.0f} fps"
+        return text
+
+
+def _coerce(value: Any) -> Optional[float]:
+    """A positive float, or None. Config reaches us with nulls and strings."""
+    if value is None or isinstance(value, bool):
+        return None
+    try:
+        number = float(value)
+    except (TypeError, ValueError):
+        return None
+    return number if number > 0 else None
+
+
+def _from_speed_and_delay(block: Any) -> Optional[float]:
+    """px/s from a ``scroll_speed`` (px/frame) + ``scroll_delay`` (s) pair."""
+    if not isinstance(block, dict):
+        return None
+    speed = _coerce(block.get("scroll_speed"))
+    delay = _coerce(block.get("scroll_delay"))
+    if speed is None or delay is None:
+        return None
+    return speed / delay
+
+
+def resolve(
+    plugin_config: Optional[Dict[str, Any]] = None,
+    global_config: Optional[Dict[str, Any]] = None,
+    default_pixels_per_second: float = DEFAULT_PIXELS_PER_SECOND,
+    refresh_hz: Optional[float] = None,
+) -> ScrollSettings:
+    """Resolve one scroll speed from the several shapes plugins accept.
+
+    Precedence, highest first. The deprecated flat key sits *below* the
+    explicit pairs deliberately: it carries schema defaults in some plugins, so
+    ranking it above them silently disables the documented settings.
+
+    1. ``display_options.scroll_speed`` + ``scroll_delay``  (current)
+    2. ``display.scroll_speed`` + ``scroll_delay``          (deprecated shape)
+    3. ``scroll_speed`` + ``scroll_delay`` at the root      (legacy flat)
+    4. ``scroll_pixels_per_second``, nested or flat         (deprecated)
+    5. the global ``display`` block
+    6. ``default_pixels_per_second``
+
+    :param refresh_hz: panel refresh, used only to check whether the resolved
+        speed lands on whole pixels per frame and to fill in ``target_fps``.
+    """
+    plugin_config = plugin_config or {}
+    global_config = global_config or {}
+    refresh = _coerce(refresh_hz) or DEFAULT_REFRESH_HZ
+
+    display_options = plugin_config.get("display_options")
+    display_block = plugin_config.get("display")
+
+    candidates = [
+        (_from_speed_and_delay(display_options), "display_options.scroll_speed/delay"),
+        (_from_speed_and_delay(display_block), "display.scroll_speed/delay"),
+        (_from_speed_and_delay(plugin_config), "scroll_speed/delay (root)"),
+    ]
+    for block, label in (
+        (display_options, "display_options.scroll_pixels_per_second"),
+        (display_block, "display.scroll_pixels_per_second"),
+        (plugin_config, "scroll_pixels_per_second"),
+    ):
+        if isinstance(block, dict):
+            candidates.append((_coerce(block.get("scroll_pixels_per_second")), label))
+
+    global_display = global_config.get("display")
+    candidates.append((_from_speed_and_delay(global_display), "global display.scroll_speed/delay"))
+
+    pixels_per_second = None
+    source = "default"
+    for value, label in candidates:
+        if value is not None:
+            pixels_per_second, source = value, label
+            break
+    if pixels_per_second is None:
+        pixels_per_second = default_pixels_per_second
+
+    clamped = max(MIN_PIXELS_PER_SECOND, min(MAX_PIXELS_PER_SECOND, pixels_per_second))
+    warning = None
+    if clamped != pixels_per_second:
+        warning = (
+            f"scroll speed {pixels_per_second:.1f} px/s out of range, "
+            f"clamped to {clamped:.1f}"
+        )
+        pixels_per_second = clamped
+
+    pixels_per_frame = pixels_per_second / refresh if refresh > 0 else None
+    if warning is None and pixels_per_frame is not None:
+        offset = abs(pixels_per_frame - round(pixels_per_frame))
+        if pixels_per_frame < 1.0 - _WHOLE_PIXEL_TOLERANCE or offset > _WHOLE_PIXEL_TOLERANCE:
+            suggestion = max(1.0, round(pixels_per_frame)) * refresh
+            warning = (
+                f"{pixels_per_second:.1f} px/s is {pixels_per_frame:.2f} px per "
+                f"refresh at {refresh:.0f}Hz, so some frames repeat and the "
+                f"scroll will judder; {suggestion:.0f} px/s divides evenly"
+            )
+
+    return ScrollSettings(
+        pixels_per_second=pixels_per_second,
+        source=source,
+        target_fps=refresh,
+        pixels_per_frame=pixels_per_frame,
+        warning=warning,
+    )
+
+
+def configure(
+    scroll_helper: Any,
+    plugin_config: Optional[Dict[str, Any]] = None,
+    global_config: Optional[Dict[str, Any]] = None,
+    default_pixels_per_second: float = DEFAULT_PIXELS_PER_SECOND,
+    refresh_hz: Optional[float] = None,
+    plugin_logger: Optional[logging.Logger] = None,
+    display_manager: Any = None,
+    snap_to_crisp: bool = True,
+) -> ScrollSettings:
+    """Resolve the config and apply it to ``scroll_helper``.
+
+    Applied in time-based mode: see the module docstring for why frame-based
+    stepping is not used. ``hasattr`` guards keep this usable against older
+    ScrollHelper builds that a plugin may be running on.
+
+    :param display_manager: consulted for the panel's refresh rate only (it can
+        see display.hardware; a plugin cannot). The frame hold is NOT applied
+        here -- see the note in the body. The caller must pass
+        ``settings.frame_hold`` to ``display_manager.set_scrolling_state(True,
+        ...)`` when it starts scrolling, or a sub-refresh speed still presents
+        a new frame every refresh and the motion falls back to fractional
+        pixels.
+    :param snap_to_crisp: move the requested speed to the nearest speed the
+        panel can show in whole pixels. On by default because a speed that does
+        not divide evenly has no good rendering, only a choice of artefacts.
+
+    :returns: the settings applied, so the caller can log or assert on them.
+    """
+    log = plugin_logger or logger
+
+    # Refresh rate, most authoritative first: what the caller passed, then the
+    # display manager (which can see display.hardware; a plugin cannot), then
+    # the global config, then the default.
+    #
+    # This has to be settled BEFORE resolve(), not after. resolve() uses the
+    # refresh to fill in target_fps, pixels_per_frame and the judder warning,
+    # so deriving it afterwards described a 100Hz panel to everyone running at
+    # 60 -- and with snap_to_crisp=False nothing downstream corrected it, so
+    # set_target_fps() paced the helper to 100 FPS on a 60Hz panel.
+    hz = _coerce(refresh_hz)
+    if hz is None and display_manager is not None:
+        hz = _coerce(getattr(display_manager, "refresh_hz", None))
+    if hz is None:
+        hz = refresh_hz_from_config(global_config)
+
+    settings = resolve(
+        plugin_config,
+        global_config,
+        default_pixels_per_second=default_pixels_per_second,
+        refresh_hz=hz,
+    )
+    applied = settings.pixels_per_second
+    choice = None
+
+    if snap_to_crisp:
+        choice = solve_crisp(settings.pixels_per_second, hz)
+        applied = choice.pixels_per_second
+        settings = replace(
+            settings,
+            pixels_per_second=applied,
+            requested_pixels_per_second=settings.pixels_per_second,
+            crisp=choice,
+            pixels_per_frame=float(choice.pixels_per_frame),
+            # Snapping resolves the whole-pixel problem the warning describes.
+            warning=None if settings.warning and "judder" in settings.warning
+            else settings.warning,
+        )
+
+    if hasattr(scroll_helper, "set_frame_based_scrolling"):
+        scroll_helper.set_frame_based_scrolling(False)
+    scroll_helper.set_scroll_speed(applied)
+    if choice and hasattr(scroll_helper, "set_target_fps"):
+        scroll_helper.set_target_fps(choice.frames_per_second)
+    elif settings.target_fps and hasattr(scroll_helper, "set_target_fps"):
+        scroll_helper.set_target_fps(settings.target_fps)
+
+    # Deliberately NOT applied here. The hold belongs to a scroll, not to a
+    # plugin's lifetime: plugins share one display manager, and one left set at
+    # construction is reset the moment any other plugin finishes scrolling.
+    # Callers pass settings.frame_hold to set_scrolling_state(True, ...) when
+    # they start scrolling. configure() only reports what is needed.
+
+    if choice:
+        requested = settings.requested_pixels_per_second
+        if abs(requested - applied) > 0.05:
+            log.info(
+                "Scroll configured: %s (asked for %.1f px/s from %s; "
+                "nearest whole-pixel speed on a %.0fHz panel)",
+                choice.describe(), requested, settings.source, hz,
+            )
+        else:
+            log.info("Scroll configured: %s (from %s)",
+                     choice.describe(), settings.source)
+        if choice.frame_hold > 1:
+            log.debug(
+                "Scroll needs a frame hold of %d - pass settings.frame_hold to "
+                "display_manager.set_scrolling_state(True, ...) each scroll",
+                choice.frame_hold,
+            )
+    else:
+        log.info("Scroll configured: %s", settings.describe())
+
+    if settings.warning:
+        log.warning("Scroll speed: %s", settings.warning)
+    return settings
+
+
+def refresh_hz_from_config(global_config: Optional[Dict[str, Any]]) -> float:
+    """The panel's refresh cap from the global config, or the default."""
+    if not isinstance(global_config, dict):
+        return DEFAULT_REFRESH_HZ
+    # Each level is checked for being a mapping rather than merely truthy: a
+    # malformed config where display or display.hardware is a string or a list
+    # raised AttributeError out of what is meant to be a total function with a
+    # default, taking down every caller that asked for the refresh rate.
+    display = global_config.get("display")
+    if not isinstance(display, dict):
+        return DEFAULT_REFRESH_HZ
+    hardware = display.get("hardware")
+    if not isinstance(hardware, dict):
+        return DEFAULT_REFRESH_HZ
+    return _coerce(hardware.get("limit_refresh_rate_hz")) or DEFAULT_REFRESH_HZ

src/common/scroll_helper.py

@@ -16,6 +16,7 @@ Features:
 """
 
 import logging
+import math
 import time
 from typing import Optional, Dict, Any
 from PIL import Image
@@ -29,6 +30,49 @@ except ImportError:
     HAS_SCIPY = False
 
 
+def frame_stats(frame_times: list) -> Dict[str, Any]:
+    """Summary statistics over one window of frame durations (seconds).
+
+    Split out of log_frame_rate() so the arithmetic can be tested without a
+    clock. Median and p95 are the real ones: the median takes both middle
+    samples on an even window, and p95 is nearest-rank, so a 100-frame window
+    reports the 95th sorted sample rather than the 96th. That matters twice
+    over, because the median is also the threshold the stall and skip counts
+    are measured against.
+    """
+    window = sorted(frame_times)
+    n = len(window)
+    median = (window[n // 2] if n % 2
+              else (window[n // 2 - 1] + window[n // 2]) / 2.0)
+    mean = sum(window) / n
+    # Anything past 1.5x the median missed a panel refresh; anything under
+    # half of it never reached the panel at all (dirty tracking skipped the
+    # swap, so the frame did not wait for vsync).
+    return {
+        "frames": n,
+        "fps": (1.0 / mean) if mean > 0 else 0.0,
+        "median": median,
+        "p95": window[max(0, math.ceil(0.95 * n) - 1)],
+        "max": window[-1],
+        "min": window[0],
+        "stalls": sum(1 for f in window if f > median * 1.5),
+        "skips": sum(1 for f in window if f < median * 0.5),
+    }
+
+
+def format_frame_stats(frame_times: list) -> str:
+    """The one-line rendering of frame_stats(), in milliseconds."""
+    s = frame_stats(frame_times)
+    n = s["frames"]
+    return (
+        f"{s['fps']:.1f} fps over {n} frames | "
+        f"median {s['median'] * 1000:.2f}ms p95 {s['p95'] * 1000:.2f}ms "
+        f"max {s['max'] * 1000:.2f}ms min {s['min'] * 1000:.2f}ms | "
+        f"stalls {s['stalls']} ({100.0 * s['stalls'] / n:.1f}%) "
+        f"skips {s['skips']} ({100.0 * s['skips'] / n:.1f}%)"
+    )
+
+
 class ScrollHelper:
     """
     Helper class for scrolling text and image content on LED displays.
@@ -75,8 +119,19 @@ class ScrollHelper:
         # Pre-allocated buffer for output frame (reused to avoid allocations)
         self._frame_buffer: Optional[np.ndarray] = None
         
-        # Sub-pixel scrolling settings (disabled - using high FPS integer scrolling instead)
-        self.sub_pixel_scrolling = False  # Disabled - use high frame rate for smoothness
+        # Sub-pixel scrolling: OFF by default, and that is deliberate.
+        # Blending renders a half-step by mixing two adjacent columns 50/50.
+        # On a high-resolution screen that reads as smooth motion; on a coarse
+        # LED matrix showing pixel-font text it does not. A one-pixel stroke
+        # becomes two half-brightness pixels, so frames alternate between crisp
+        # and smeared and the text appears to shimmer and jump a pixel ahead --
+        # tested on a 2x128x64 panel and clearly worse than integer stepping.
+        #
+        # The rule this display obeys: motion is smooth when it advances a
+        # whole number of pixels per refresh. Anything slower must either
+        # blend (blur) or repeat frames (judder); blending is the worse of the
+        # two here. Vegas mode still opts in via set_sub_pixel_scrolling().
+        self.sub_pixel_scrolling = False
         self._last_integer_position = 0  # Cache for integer position to avoid repeated calculations
         
         # Frame-based scrolling settings
@@ -105,6 +160,9 @@ class ScrollHelper:
         self.last_frame_time = time.time()
         self.last_fps_log_time = time.time()
         self.frame_times = []
+        # Every frame time since the last stats line, so the 5s summary can
+        # report the tail rather than one arbitrary sample. Cleared on log.
+        self._window: list = []
         
         # Scrolling state management
         self.is_scrolling = False
@@ -244,19 +302,31 @@ class ScrollHelper:
             if self.last_step_time == 0.0:
                 self.last_step_time = current_time
             
-            # Check if scroll_delay has passed
-            time_since_last_step = current_time - self.last_step_time
-            if time_since_last_step >= self.scroll_delay:
-                # Move pixels (can move multiple steps if lag occurred, but cap to prevent huge jumps)
-                steps = int(time_since_last_step / self.scroll_delay)
-                # Cap at reasonable number to prevent huge jumps from lag
-                max_steps = max(1, int(0.04 / self.scroll_delay))  # Limit to 0.04s (2 steps at 50 FPS) for smoother scrolling
-                steps = min(steps, max_steps)
-                pixels_to_move = self.scroll_speed * steps
-                # Update last_step_time, preserving fractional delay for smooth timing
-                self.last_step_time = current_time - (time_since_last_step % self.scroll_delay)
+            # Frame-based mode advances by elapsed time, exactly like the
+            # time-based branch below, at the same configured speed
+            # (scroll_speed px per scroll_delay seconds).
+            #
+            # It used to step discretely: 0, 1 or 2 whole pixels depending on
+            # whether a wall clock had passed scroll_delay. Plugins set
+            # scroll_delay to the target frame period, so that comparison sits
+            # exactly on its own threshold and the decision flips on sub-
+            # millisecond jitter -- a frame a hair early moved nothing and
+            # rendered an identical frame, a frame a hair late moved two
+            # pixels. Rounding the step count fixed the stalls but still
+            # discarded the remainder, so the error never corrected.
+            #
+            # Accumulating elapsed time keeps position exactly proportional to
+            # real time: jitter shifts a pixel boundary by a fraction of a
+            # frame instead of flipping a whole step, and nothing is lost or
+            # gained. This is what the one visibly smooth scroller on the
+            # hardware (the stock ticker) was already doing by virtue of never
+            # enabling frame-based mode.
+            if self.scroll_delay > 0:
+                pixels_per_second = self.scroll_speed / self.scroll_delay
             else:
-                pixels_to_move = 0.0
+                pixels_per_second = self.scroll_speed * 100.0
+            pixels_to_move = pixels_per_second * delta_time
+            self.last_step_time = current_time
         else:
             # Time-based: move based on time delta (correct speed over time)
             # scroll_speed is pixels per second
@@ -1018,17 +1088,24 @@ class ScrollHelper:
         if len(self.frame_times) > 100:
             self.frame_times.pop(0)
 
+        # Every frame since the last log, not just the last 100 and not just
+        # the one that happens to land on the 5s boundary. The old line
+        # reported a single instantaneous sample -- roughly 1 frame in 500 --
+        # which cannot see a stall that hits 1% of frames, and reported it
+        # next to an average that hides the same stall by construction (a 2ms
+        # duplicate and a 21ms double-wait mean exactly 10ms). Chasing scroll
+        # judder needs the tail, so keep the window and report percentiles.
+        self._window.append(frame_time)
+        
         # Log FPS every 5 seconds to avoid spam
         if current_time - self.last_fps_log_time >= 5.0:
-            avg_frame_time = sum(self.frame_times) / len(self.frame_times)
-            avg_fps = 1.0 / avg_frame_time if avg_frame_time > 0 else 0
-            instant_fps = 1.0 / frame_time if frame_time > 0 else 0
-            
-            self.logger.info(f"Scroll frame stats - Avg FPS: {avg_fps:.1f}, "
-                           f"Current FPS: {instant_fps:.1f}, "
-                           f"Frame time: {frame_time*1000:.2f}ms")
+            self.logger.info(
+                "Scroll frame stats - %s",
+                format_frame_stats(self._window or [frame_time]),
+            )
             self.last_fps_log_time = current_time
             self.frame_count = 0
+            self._window = []
         
         self.last_frame_time = current_time
         self.frame_count += 1

src/display_controller.py

@@ -198,6 +198,10 @@ class DisplayController:
         # the main run loop reconciles (loads/unloads) on its own thread so
         # mutating available_modes never races with rendering.
         self._pending_plugin_reconcile = False
+        # Monotonic stamp of the last mailbox disk read; see
+        # _poll_on_demand_requests. None means "never polled", so the first
+        # call always goes through.
+        self._last_on_demand_poll: Optional[float] = None
         self.on_demand_active = False
         self.on_demand_mode: Optional[str] = None
         self.on_demand_modes: List[str] = []  # All modes for the on-demand plugin
@@ -1267,12 +1271,34 @@ class DisplayController:
         self.on_demand_schedule_override = False
         self._publish_on_demand_state()
 
+    #: Shortest gap between mailbox disk reads. This is called after every
+    #: frame -- about 125 times a second on a scrolling mode -- and the read
+    #: below is deliberately uncached, so without a floor it was 125 disk reads
+    #: per second to find nothing. An on-demand request comes from a person
+    #: clicking in the web UI, so a quarter second of latency is not
+    #: perceptible, and it cuts the read rate by 30x.
+    ON_DEMAND_POLL_INTERVAL = 0.25
+
     def _poll_on_demand_requests(self) -> None:
         """Poll cache for new on-demand requests from external controllers."""
+        now = time.monotonic()
+        if (self._last_on_demand_poll is not None
+                and now - self._last_on_demand_poll < self.ON_DEMAND_POLL_INTERVAL):
+            return
+        self._last_on_demand_poll = now
+
         try:
             # Use a long max_age (1 hour) to ensure requests aren't expired before processing
-            # The request_id check prevents duplicate processing
-            request = self.cache_manager.get('display_on_demand_request', max_age=3600)
+            # The request_id check prevents duplicate processing.
+            #
+            # memory_ttl=0 is required, not optional: this key is a mailbox the
+            # web process writes and this process reads. get() defaults the
+            # in-memory TTL to max_age, so without it the first request read was
+            # pinned in memory for the full hour and every later poll returned
+            # that stale copy -- meaning no second on-demand request was honoured
+            # for an hour, while the API still reported success.
+            request = self.cache_manager.get('display_on_demand_request',
+                                             max_age=3600, memory_ttl=0)
         except (OSError, RuntimeError, ValueError, TypeError) as err:
             logger.error("Failed to read on-demand request: %s", err, exc_info=True)
             return
@@ -1318,6 +1344,36 @@ class DisplayController:
         # Mark as processed BEFORE processing (to prevent duplicate processing)
         self.cache_manager.set('display_on_demand_processed_id', request_id, ttl=3600)
         self.on_demand_request_id = request_id
+        # Consume the mailbox entry. Leaving it on disk meant a restart replayed
+        # the previous request: the fresh controller read it, activated it and
+        # cached it, so the request the caller had just made was ignored and the
+        # panel silently showed the earlier plugin. processed_id still guards
+        # against double-processing if this delete fails.
+        try:
+            # Compare before deleting. The web process can post a newer request
+            # between the read above and this delete; an unconditional delete
+            # threw that one away and it was never processed -- the user's
+            # second click did nothing. Re-reading uncached and only deleting
+            # our own request_id means a newer request is left in the mailbox
+            # for the next poll instead.
+            #
+            # This narrows the window rather than closing it: a request landing
+            # between this re-read and the delete is still lost. Closing it
+            # properly needs an atomic claim (a rename, or a compare-and-delete
+            # primitive) that the cache layer does not currently offer, so the
+            # honest fix is a smaller window plus this note, not a bigger lock.
+            current = self.cache_manager.get('display_on_demand_request',
+                                             max_age=3600, memory_ttl=0)
+            if not current or current.get('request_id') == request_id:
+                self.cache_manager.delete('display_on_demand_request')
+            else:
+                logger.debug("Newer on-demand request %s arrived while processing "
+                             "%s; leaving it in the mailbox",
+                             current.get('request_id'), request_id)
+        except (OSError, AttributeError, KeyError) as err:
+            # Best-effort: processed_id still guards against reprocessing if the
+            # mailbox cannot be cleared.
+            logger.debug("Could not clear the on-demand request mailbox: %s", err)
         
         if action == 'start':
             logger.info("Processing on-demand start request for plugin: %s", request.get('plugin_id'))
@@ -2405,6 +2461,7 @@ class DisplayController:
                             )
 
                             while True:
+                                _frame_start = time.perf_counter()
                                 try:
                                     with self._display_lock_or_skip(plugin_id) as can_display:
                                         if can_display:
@@ -2425,11 +2482,26 @@ class DisplayController:
                                 # Multi-display sync: send follower frame after each render
                                 self._send_follower_frame(manager_to_display)
 
-                                time.sleep(display_interval)
                                 self._tick_plugin_updates()
                                 self._poll_on_demand_requests()
                                 self._check_on_demand_expiration()
 
+                                # Pace to the frame deadline rather than sleeping a flat
+                                # interval on top of the work. display() has already
+                                # blocked on the panel's vsync by this point, so an
+                                # unconditional sleep is added to a wait that already
+                                # happened. Measured on a 2x128x64 chain at
+                                # limit_refresh_rate_hz=100: ~4ms of render plus a flat
+                                # 8ms put each iteration at ~12ms against a 10ms refresh
+                                # grid, so every swap missed a refresh and the loop
+                                # settled at 50fps where display_interval asks for 125 --
+                                # and with zero headroom, ~14% of frames slipped a
+                                # further refresh, which is what reads as scroll stutter.
+                                _remaining = display_interval - (time.perf_counter() - _frame_start)
+                                # Yield even when the frame overran its budget, so plugin
+                                # update threads and the web UI are not starved of the GIL.
+                                time.sleep(_remaining if _remaining > 0 else 0.001)
+
                                 if self.current_display_mode != active_mode:
                                     logger.debug("Mode changed during high-FPS loop, breaking early")
                                     break

src/display_manager.py

@@ -240,6 +240,14 @@ class DisplayManager:
         self._update_lock = threading.RLock()
         
         # Scrolling state tracking for graceful updates
+        # How many panel refreshes each pushed frame is held for. 1 means a new
+        # frame every refresh. Higher values are how a scroll runs slower than
+        # one pixel per refresh WITHOUT fractional pixel positions: the panel
+        # keeps refreshing at full rate (so flicker is unchanged) but motion
+        # advances a whole pixel every Nth refresh instead of every one.
+        # See src/common/scroll_config.py and scripts/scroll_speeds.py.
+        self._frame_hold = 1
+
         self._scrolling_state = {
             'is_scrolling': False,
             'last_scroll_activity': 0,
@@ -771,16 +779,33 @@ class DisplayManager:
                     return  # Skip hardware write — content is being captured off-screen
 
                 digest = None
+                frame_checksum = None
                 if self._dirty_tracking_enabled:
                     try:
                         brightness = getattr(self.matrix, 'brightness', None)
                     except AttributeError:
                         brightness = None
-                    digest = (zlib.adler32(self.image.tobytes()), brightness)
-                    if digest == self._last_pushed_digest:
+                    frame_checksum = zlib.adler32(self.image.tobytes())
+                    digest = (frame_checksum, brightness)
+                    if digest == self._last_pushed_digest and not self.is_currently_scrolling():
                         # Nothing changed since the last push — the panel is
                         # already showing exactly this frame.
-                        self._write_snapshot_if_due()
+                        #
+                        # Never taken mid-scroll, and that exception is the
+                        # point. SwapOnVSync is what paces the render loop, so
+                        # skipping it also skips the wait: a duplicate frame
+                        # returns in ~8ms instead of ~10ms on a 100Hz panel,
+                        # advances only 0.8px instead of 1.0px, and so makes
+                        # the *next* frame more likely to repeat as well. That
+                        # is self-sustaining -- measured at ~20% duplicate
+                        # frames mid-scroll on the odds ticker, against
+                        # essentially zero on a lighter plugin with identical
+                        # scroll settings. Swapping an identical frame costs
+                        # one canvas copy and keeps the loop locked to the
+                        # panel; falling out of that lock costs smooth motion.
+                        # Static content is unaffected: is_currently_scrolling()
+                        # expires on its own inactivity threshold.
+                        self._write_snapshot_if_due(frame_checksum)
                         return
 
                 # Copy the current image to the offscreen canvas. In double-sided
@@ -790,8 +815,10 @@ class DisplayManager:
                 else:
                     self.offscreen_canvas.SetImage(self.image)
 
-                # Swap buffers immediately
-                self.matrix.SwapOnVSync(self.offscreen_canvas)
+                # Swap buffers immediately. framerate_fraction holds the frame
+                # for N refreshes; SwapOnVSync blocks for all of them, which is
+                # what paces the render loop to the chosen frame rate.
+                self.matrix.SwapOnVSync(self.offscreen_canvas, self._frame_hold)
 
                 # Swap our canvas references
                 self.offscreen_canvas, self.current_canvas = self.current_canvas, self.offscreen_canvas
@@ -799,7 +826,7 @@ class DisplayManager:
                 self._last_pushed_digest = digest
 
                 # Write a snapshot for the web preview (throttled)
-                self._write_snapshot_if_due()
+                self._write_snapshot_if_due(frame_checksum)
         except Exception as e:
             logger.error(f"Error updating display: {e}")
 
@@ -1280,12 +1307,65 @@ class DisplayManager:
         
         return dt.strftime(f"%b %-d{suffix}") 
 
-    def set_scrolling_state(self, is_scrolling: bool):
-        """Set the current scrolling state. Call this when a display starts/stops scrolling."""
+    @property
+    def refresh_hz(self) -> float:
+        """The panel's refresh rate in Hz, from the hardware config.
+
+        The authoritative place to ask, because a plugin only receives its own
+        config section and cannot see display.hardware. Scroll pacing needs
+        this: the speeds a panel can show in whole pixels are refresh_hz
+        divided by the frame hold, so getting it wrong silently produces
+        fractional-pixel motion. See src/common/scroll_config.py.
+
+        Note this is the configured *cap*, not necessarily what the panel
+        achieves -- scripts/scroll_speeds.py --measure reports the real rate.
+        """
+        hardware = (self.config.get('display') or {}).get('hardware') or {}
+        try:
+            value = float(hardware.get('limit_refresh_rate_hz') or 0)
+        except (TypeError, ValueError):
+            value = 0.0
+        return value if value > 0 else 100.0
+
+    def set_frame_hold(self, refreshes: int) -> None:
+        """Hold each pushed frame for this many panel refreshes (>=1).
+
+        Set by the scroll configuration so a plugin can run at, say, 50px/s on
+        a 100Hz panel as one whole pixel every second refresh, rather than half
+        a pixel every refresh (which has to be blended or repeated unevenly).
+
+        Reset to 1 whenever scrolling stops, so one plugin's pacing cannot
+        leak into the next thing on screen.
+        """
+        try:
+            value = int(refreshes)
+        except (TypeError, ValueError):
+            logger.warning("Ignoring unusable frame hold: %r", refreshes)
+            return
+        self._frame_hold = max(1, min(255, value))
+
+    def set_scrolling_state(self, is_scrolling: bool, frame_hold: int = 1):
+        """Set the current scrolling state, and this scroll's frame pacing.
+
+        Call this when a display starts or stops scrolling. ``frame_hold`` is
+        how many panel refreshes each frame is held for -- 2 gives one whole
+        pixel every second refresh, which is how a scroll runs at half the
+        refresh rate without fractional pixel positions.
+
+        The hold is set here rather than once at plugin construction because
+        it must not outlive the scroll that asked for it: plugins share one
+        display manager, so a hold left set by whoever scrolled last would
+        silently re-pace the next plugin. Passing it alongside the state makes
+        the lifetime exactly the scroll, and the default of 1 means any caller
+        that does not care gets a new frame every refresh.
+        """
         current_time = time.time()
         self._scrolling_state['is_scrolling'] = is_scrolling
         if is_scrolling:
             self._scrolling_state['last_scroll_activity'] = current_time
+            self.set_frame_hold(frame_hold)
+        else:
+            self._frame_hold = 1
         logger.debug(f"Scrolling state set to: {is_scrolling}")
 
     def is_currently_scrolling(self) -> bool:
@@ -1416,11 +1496,20 @@ class DisplayManager:
                 self._viewer_fresh = False
         return self._viewer_fresh
 
-    def _write_snapshot_if_due(self) -> None:
+    def _write_snapshot_if_due(self, frame_checksum: Optional[int] = None) -> None:
         """Mirror the current frame to the preview snapshot when the policy
         says it's worth it — see src/common/snapshot_policy.py. Unchanged
         frames are never re-encoded; without viewers the cadence drops to
-        the idle keepalive."""
+        the idle keepalive.
+
+        Args:
+            frame_checksum: adler32 of the current frame, when the caller has
+                already computed one. Dirty tracking checksums every frame a
+                few lines above the call site, and re-deriving it here meant a
+                second tobytes() plus a second pass over the whole framebuffer
+                on every single frame — ~0.17ms per frame of the two combined
+                at 256x64, paid 100 times a second to reach the same number.
+        """
         try:
             now = time.time()
             viewer_fresh = self._viewer_is_fresh(now)
@@ -1430,7 +1519,8 @@ class DisplayManager:
                 self._last_snapshot_ts = 0.0
             self._viewer_was_fresh = viewer_fresh
 
-            digest = zlib.adler32(self.image.tobytes())
+            digest = (frame_checksum if frame_checksum is not None
+                      else zlib.adler32(self.image.tobytes()))
             action = snapshot_policy.decide(
                 now, self._last_snapshot_ts, self._last_snapshot_touch_ts,
                 viewer_fresh, digest != self._last_snapshot_digest)
@@ -1453,12 +1543,30 @@ class DisplayManager:
                 if parent_dir and str(parent_dir) != '/tmp':  # nosec B108 - guard to skip /tmp for permission ops
                     ensure_directory_permissions(parent_dir, get_assets_dir_mode())
                 self._snapshot_dir_prepared = True
-            # Write atomically: temp then replace
-            tmp_path = f"{self._snapshot_path}.tmp"
-            self.image.save(tmp_path, format='PNG')
+            # Write atomically: temp then replace. The temp name must be
+            # unique, not "<snapshot>.tmp": /tmp is world-writable and sticky,
+            # and this file is written by whichever user the display service
+            # runs as while tests and tooling run as someone else. A leftover
+            # fixed-name temp owned by another user is then unopenable even by
+            # root (fs.protected_regular refuses O_CREAT on a foreign file in a
+            # sticky dir), which froze the preview and the health check's
+            # liveness proxy until somebody deleted it by hand. Same pattern as
+            # the hardware-status write above.
+            _fd, tmp_path = tempfile.mkstemp(
+                dir=str(snapshot_path_obj.parent),
+                prefix=f".{snapshot_path_obj.name}.", suffix=".tmp")
             try:
+                with os.fdopen(_fd, "wb") as _f:
+                    self.image.save(_f, format='PNG')
+                os.chmod(tmp_path, 0o644)
                 os.replace(tmp_path, self._snapshot_path)
             except Exception:
+                # Never leave the temp behind -- that is what made the failure
+                # permanent rather than transient.
+                try:
+                    os.unlink(tmp_path)
+                except OSError:
+                    pass
                 # Fallback to direct save if replace not supported
                 self.image.save(self._snapshot_path, format='PNG')
             # Set proper file permissions after saving

src/font_manager.py

@@ -96,7 +96,8 @@ class FontManager:
         self.common_fonts = {
             "press_start": "assets/fonts/PressStart2P-Regular.ttf",
             "four_by_six": "assets/fonts/4x6-font.ttf",
-            "five_by_seven": "assets/fonts/5x7.bdf"
+            "five_by_seven": "assets/fonts/5x7.bdf",
+            "tom_thumb": "assets/fonts/tom-thumb.bdf"
             # Note: cozette_bdf removed - font file not available
             # To re-enable: download cozette.bdf from https://github.com/the-moonwitch/Cozette
             # and add: "cozette_bdf": "assets/fonts/cozette.bdf"

src/plugin_system/store_manager.py

@@ -1589,6 +1589,7 @@ class PluginStoreManager:
             with open(manifest_path, 'r') as f:
                 manifest = json.load(f)
             
+            requested_id = plugin_id
             plugin_id = plugin_id or manifest.get('id')
             if not plugin_id:
                 return {
@@ -1664,6 +1665,15 @@ class PluginStoreManager:
             
             branch_info = f" (branch: {branch_used})" if branch_used else ""
             self.logger.info(f"Successfully installed plugin from URL: {plugin_id}{branch_info}")
+            # User deliberately (re)installed this plugin -- clear any persistent
+            # uninstall record, exactly as install_plugin() does. Without this the
+            # id stays in config/uninstalled_plugins.json and
+            # purge_uninstalled_plugins(), which runs at every web-app startup,
+            # deletes the directory again: the plugin works for the rest of the
+            # session and is gone after the next reboot.
+            self.forget_uninstalled_plugin(
+                *(pid for pid in (requested_id, plugin_id, manifest.get('id')) if pid)
+            )
             result = {
                 'success': True,
                 'plugin_id': plugin_id,
@@ -2424,6 +2434,65 @@ class PluginStoreManager:
         except (OSError, ValueError):
             pass
 
+        # Last resort: the directory name may differ from the id being looked
+        # up. install_plugin() deliberately renames a plugin's directory to the
+        # MANIFEST id when it differs from the REGISTRY id (see the rename near
+        # "doesn't match registry ID" above), so `stocks` in the registry lands
+        # in `ledmatrix-stocks/`. Every lookup above is by directory name, so
+        # update_plugin("stocks") found nothing and reported the plugin as not
+        # installed -- silently, and for good: the user sees no error and stays
+        # on a stale version. Four installed plugins hit this in practice
+        # (leaderboard, music, stocks, weather).
+        #
+        # Deliberately last so the two lookups above keep their exact meaning;
+        # this only runs when a direct hit already failed. See
+        # test_discovery_path_contract.py, which pins that ordering.
+        for search_dir in self._candidate_plugin_dirs():
+            match = self._find_by_manifest_id(search_dir, plugin_id)
+            if match is not None:
+                self.logger.debug(
+                    "Resolved plugin '%s' to %s via its manifest id "
+                    "(directory name differs from the id)", plugin_id, match)
+                return match
+
+        return None
+
+    def _candidate_plugin_dirs(self) -> List[Path]:
+        """Directories that may hold installed plugins, configured one first."""
+        dirs = [self.plugins_dir]
+        try:
+            base = self.plugins_dir if self.plugins_dir.is_absolute()                 else self.plugins_dir.resolve()
+            sibling = base.parent / 'plugins'
+            if sibling != self.plugins_dir:
+                dirs.append(sibling)
+        except (OSError, ValueError):
+            pass
+        return [d for d in dirs if d.exists()]
+
+    @staticmethod
+    def _find_by_manifest_id(search_dir: Path, plugin_id: str) -> Optional[Path]:
+        """A subdirectory of `search_dir` whose manifest declares `plugin_id`.
+
+        Skips half-finished installs: store_manager renames a directory aside
+        with '.standalone-backup-' during install and rollback, and treating
+        one as installed would resurrect a ghost plugin.
+        """
+        try:
+            entries = sorted(search_dir.iterdir())
+        except (OSError, ValueError):
+            return None
+        for entry in entries:
+            if not entry.is_dir() or '.standalone-backup-' in entry.name:
+                continue
+            manifest = entry / 'manifest.json'
+            if not manifest.is_file():
+                continue
+            try:
+                with open(manifest, 'r', encoding='utf-8') as handle:
+                    if json.load(handle).get('id') == plugin_id:
+                        return entry
+            except (OSError, ValueError):
+                continue
         return None
     
     _SKIN_ID_PATTERN = re.compile(r'^[A-Za-z0-9][A-Za-z0-9._-]{0,63}$')

src/plugin_system/testing/harness.py

@@ -14,6 +14,8 @@ via BoundsCheckingDisplayManager, and golden-image comparison.
 import contextlib
 import http.client
 import inspect
+import time
+from datetime import timedelta
 import socket
 import ssl
 import urllib.error
@@ -25,7 +27,7 @@ from PIL import Image, ImageChops
 
 from src.logging_config import get_logger
 from .bounds_display_manager import BoundsCheckingDisplayManager
-from .loading import load_config_defaults, load_manifest
+from .loading import load_config_defaults, load_manifest, merge_config
 from .sizes import DEFAULT_TEST_SIZES, safe_mode_filename, size_label
 
 logger = get_logger("[Plugin Harness]")
@@ -116,11 +118,20 @@ def list_modes(plugin_instance: Any, manifest: Dict[str, Any], plugin_id: str) -
 
 def _instantiate(plugin_id: str, manifest: Dict[str, Any], plugin_dir: Path,
                  config: Dict[str, Any], mock_data: Dict[str, Any],
-                 display_manager: Any) -> Any:
-    """Load and construct a plugin instance with mocked managers."""
+                 display_manager: Any, cache_manager: Any = None) -> Any:
+    """Load and construct a plugin instance with mocked managers.
+
+    Pass ``cache_manager`` to share one cache across the renders of a plugin.
+    Building a fresh one per (size, mode) made every render a cold start, so a
+    plugin that fetches per game or per player re-fetched everything N times --
+    baseball-scoreboard took 840s for nine renders where ~72s was the arithmetic
+    -- and the cache-hit path, which is what a running rig executes almost
+    always, was never exercised.
+    """
     from src.plugin_system.plugin_loader import PluginLoader
     from src.plugin_system.testing import MockCacheManager, MockPluginManager
 
+    if cache_manager is None:
         cache_manager = MockCacheManager()
         for key, value in (mock_data or {}).items():
             cache_manager.set(key, value)
@@ -160,6 +171,107 @@ def _render_mode(plugin_instance: Any, mode: str) -> Any:
     return plugin_instance.display(force_clear=False)
 
 
+# How many extra frames to drive before believing a mode really draws nothing.
+# A scroll starts with its content off-panel, so frame 1 is legitimately blank;
+# measured across the fleet, content appears by frame 2-4 (f1-scoreboard),
+# frame 4 (ledmatrix-elections) and frame 38 at 64px (ledmatrix-leaderboard).
+EMPTY_RECHECK_FRAMES = 48
+# Seconds to advance the clock between those frames. Scroll position is usually
+# driven by elapsed time, which a frozen clock never provides.
+EMPTY_RECHECK_STEP = 0.05
+
+
+def _has_content(image) -> bool:
+    """True when any pixel is lit above the threshold."""
+    if image is None:
+        return False
+    return image.convert("L").point(
+        lambda p: 255 if p > _LIT_THRESHOLD else 0).getbbox() is not None
+
+
+def _render_mode_again(plugin_instance: Any, mode: str) -> Any:
+    """Draw one more frame WITHOUT force_clear.
+
+    _render_mode passes force_clear=True, which for a scrolling plugin means
+    "reset the scroll to the start" -- so repeating it would redraw frame 1 for
+    ever. The re-check needs the plugin to advance.
+    """
+    sig = inspect.signature(plugin_instance.display)
+    if "display_mode" in sig.parameters:
+        return plugin_instance.display(force_clear=False, display_mode=mode)
+    return plugin_instance.display(force_clear=False)
+
+
+def _settle_empty_frame(inst, mode, dm, result, freezer) -> None:
+    """Give an apparently-empty mode a few frames to draw before believing it.
+
+    One frame is not evidence: a scroll's first frame is its blank scroll-in
+    buffer. Without this, every scrolling plugin was warned about -- 60 of 76
+    warnings on a 44-plugin rig were false, which is the rate at which people
+    stop reading a warning.
+    """
+    if result.error is not None or result.display_returned is False:
+        return
+    if _has_content(result.image):
+        return
+    # The frozen clock is shared by every render in the matrix, so any time this
+    # probe borrows has to be given back -- otherwise a mode that scrolls in
+    # leaves the clock advanced and every later mode renders at the wrong
+    # instant, drifting its golden. Seen as 5 spurious f1_upcoming drifts.
+    resume_at = None
+    if freezer is not None:
+        try:
+            resume_at = freezer()
+        except (AttributeError, TypeError, ValueError):
+            # Not a freezegun factory, or a version whose factory is not
+            # callable. Only used to restore the clock, never load-bearing.
+            resume_at = None
+    try:
+        _settle_loop(inst, mode, dm, result, freezer)
+    finally:
+        if resume_at is not None:
+            try:
+                freezer.move_to(resume_at)
+            except (AttributeError, TypeError, ValueError):
+                pass
+
+
+def _settle_loop(inst, mode, dm, result, freezer) -> None:
+    tick = getattr(freezer, "tick", None) if freezer is not None else None
+    for _ in range(EMPTY_RECHECK_FRAMES):
+        if tick is not None:
+            # timedelta rather than a bare float: freezegun has accepted a
+            # number only since 1.x, and a stale pin would raise here.
+            try:
+                tick(timedelta(seconds=EMPTY_RECHECK_STEP))
+            except (AttributeError, TypeError, ValueError):
+                # Pacing is best-effort; a freezegun that will not take a
+                # timedelta just means this probe runs without advancing time.
+                pass
+        else:
+            # No frozen clock, so the real one has to do the advancing. Without
+            # this the 48 frames run in microseconds, elapsed time stays ~0, and
+            # a scroll driven by elapsed time never moves -- which is exactly
+            # the plugin this check is trying not to slander.
+            time.sleep(EMPTY_RECHECK_STEP)
+        try:
+            result.display_returned = _render_mode_again(inst, mode)
+        except Exception as e:  # noqa: BLE001
+            # Deliberately broad: this calls a plugin's display(), which can
+            # raise anything. Recorded rather than swallowed -- a mode that
+            # renders one good frame and then crashes on the next is broken,
+            # and returning silently here reported it as passing. The frame
+            # already captured stays on the result so the failure is still
+            # inspectable.
+            result.error = repr(e)
+            return
+        image = dm.get_image()
+        if _has_content(image):
+            result.image = image
+            result.overflow = dm.check_overflow()
+            return
+
+
 def _freeze(freeze_time: Optional[str]):
     """Context manager that freezes wall-clock time when freeze_time is given,
     so time-dependent plugins (clocks, countdowns) render deterministic goldens."""
@@ -193,7 +305,9 @@ def render_plugin_matrix(
     manifest = load_manifest(plugin_dir)
     # Start from config_schema.json defaults so the plugin behaves like a real
     # install; explicit caller config still wins over a schema default.
-    config = {"enabled": True, **load_config_defaults(plugin_dir), **(config or {})}
+    config = merge_config(
+        merge_config({"enabled": True}, load_config_defaults(plugin_dir)),
+        config or {})
     sizes = sizes or DEFAULT_TEST_SIZES
     results: List[RenderResult] = []
 
@@ -202,25 +316,35 @@ def render_plugin_matrix(
     # rendering a smaller one, instead of being clipped into a false pass.
     extent = (max(w for w, _ in sizes), max(h for _, h in sizes))
 
-    with _freeze(freeze_time):
+    # One cache for the whole matrix: see _instantiate. The display manager
+    # stays per-render (the bounds checking depends on that); only fetched data
+    # is shared.
+    from src.plugin_system.testing import MockCacheManager
+    cache_manager = MockCacheManager()
+    for key, value in (mock_data or {}).items():
+        cache_manager.set(key, value)
+
+    with _freeze(freeze_time) as freezer:
         for width, height in sizes:
             results.extend(_render_size(
                 plugin_id, manifest, plugin_dir, config, mock_data or {},
-                width, height, run_update, extent,
+                width, height, run_update, extent, cache_manager, freezer,
             ))
 
     return results
 
 
 def _render_size(plugin_id, manifest, plugin_dir, config, mock_data,
-                 width, height, run_update, extent) -> List[RenderResult]:
+                 width, height, run_update, extent,
+                 cache_manager=None, freezer=None) -> List[RenderResult]:
     """Render every mode at one size. A fresh instance per mode avoids state leaks."""
     results: List[RenderResult] = []
 
     # Discover modes once per size (instance build can depend on config).
     try:
         probe_dm = BoundsCheckingDisplayManager(width=width, height=height, overflow_extent=extent)
-        probe = _instantiate(plugin_id, manifest, plugin_dir, config, mock_data, probe_dm)
+        probe = _instantiate(plugin_id, manifest, plugin_dir, config, mock_data, probe_dm,
+                             cache_manager)
         modes = list_modes(probe, manifest, plugin_id)
     except Exception as e:  # noqa: BLE001 — surface any load failure as a result
         return [RenderResult(plugin_id, width, height, "<load>", error=repr(e))]
@@ -229,7 +353,8 @@ def _render_size(plugin_id, manifest, plugin_dir, config, mock_data,
         result = RenderResult(plugin_id, width, height, mode)
         dm = BoundsCheckingDisplayManager(width=width, height=height, overflow_extent=extent)
         try:
-            inst = _instantiate(plugin_id, manifest, plugin_dir, config, mock_data, dm)
+            inst = _instantiate(plugin_id, manifest, plugin_dir, config, mock_data, dm,
+                                cache_manager)
             if run_update:
                 try:
                     inst.update()
@@ -248,6 +373,9 @@ def _render_size(plugin_id, manifest, plugin_dir, config, mock_data,
                 result.display_returned = _render_mode(inst, mode)
                 result.image = dm.get_image()
                 result.overflow = dm.check_overflow()
+                # A blank first frame is not proof of a blank mode; see
+                # _settle_empty_frame.
+                _settle_empty_frame(inst, mode, dm, result, freezer)
         except Exception as e:  # noqa: BLE001 — a display crash is a real failure
             result.error = repr(e)
         results.append(result)

src/plugin_system/testing/loading.py

@@ -33,6 +33,45 @@ def load_manifest(plugin_dir: Union[str, Path]) -> Dict[str, Any]:
         return json.load(f)
 
 
+def _defaults_from_properties(properties: Dict[str, Any]) -> Dict[str, Any]:
+    """Defaults for one `properties` block, recursing into nested objects.
+
+    An object property carries its defaults on its children, not on itself, so
+    reading only the top level dropped everything nested. That is most of the
+    fleet: config organised by league, or under customization/display_options,
+    lost 2,386 defaults across 37 of 44 plugins -- soccer-scoreboard alone lost
+    539 of 565 -- and the harness rendered them with a config no install would
+    ever have.
+    """
+    defaults: Dict[str, Any] = {}
+    for key, prop in (properties or {}).items():
+        if not isinstance(prop, dict):
+            continue
+        if prop.get('type') == 'object' and isinstance(prop.get('properties'), dict):
+            nested = _defaults_from_properties(prop['properties'])
+            if nested:
+                defaults[key] = nested
+        elif 'default' in prop:
+            defaults[key] = prop['default']
+    return defaults
+
+
+def merge_config(base: Dict[str, Any], override: Dict[str, Any]) -> Dict[str, Any]:
+    """Deep-merge override onto base, without dropping sibling defaults.
+
+    A shallow merge would let `-c '{"nhl": {"enabled": true}}'` replace the whole
+    nhl subtree and silently discard every other nhl default -- the same class of
+    bug this function exists to fix.
+    """
+    merged = dict(base)
+    for key, value in (override or {}).items():
+        if isinstance(value, dict) and isinstance(merged.get(key), dict):
+            merged[key] = merge_config(merged[key], value)
+        else:
+            merged[key] = value
+    return merged
+
+
 def load_config_defaults(plugin_dir: Union[str, Path]) -> Dict[str, Any]:
     """Extract default values from a plugin's config_schema.json (empty if none)."""
     schema_path = Path(plugin_dir) / 'config_schema.json'
@@ -40,11 +79,7 @@ def load_config_defaults(plugin_dir: Union[str, Path]) -> Dict[str, Any]:
         return {}
     with open(schema_path, 'r') as f:
         schema = json.load(f)
-    defaults: Dict[str, Any] = {}
-    for key, prop in schema.get('properties', {}).items():
-        if isinstance(prop, dict) and 'default' in prop:
-            defaults[key] = prop['default']
-    return defaults
+    return _defaults_from_properties(schema.get('properties', {}))
 
 
 def load_harness_spec(plugin_dir: Union[str, Path]) -> Dict[str, Any]:

src/plugin_system/testing/visual_display_manager.py

@@ -506,9 +506,18 @@ class VisualTestDisplayManager:
     # Scrolling state (no-op interface compat)
     # ------------------------------------------------------------------
 
-    def set_scrolling_state(self, is_scrolling: bool):
-        """Set the current scrolling state (no-op for testing)."""
+    def set_scrolling_state(self, is_scrolling: bool, frame_hold: int = 1):
+        """Set the current scrolling state (no-op for testing).
+
+        ``frame_hold`` mirrors the DisplayManager signature this change adds.
+        The two are kept in step deliberately: a double that accepts arguments
+        production does not lets a call pass every harness run and then raise
+        TypeError on the panel, and a double that lacks one production has
+        fails every render of a plugin that legitimately paces its scroll.
+        Plugins begin passing it in ledmatrix-plugins#462.
+        """
         self._scrolling_state['is_scrolling'] = is_scrolling
+        self._scrolling_state['frame_hold'] = frame_hold
         if is_scrolling:
             self._scrolling_state['last_scroll_activity'] = time.time()
 

test/test_app_plugins_dir_resolution.py

@@ -1,52 +0,0 @@
-"""web_interface/app.py resolves plugins_dir from config at import time.
-
-`project_root` used to be assigned only inside the `else` branch (the
-relative-path case). SchemaManager and composer_bp are wired up with
-`project_root` further down the same module, so a device configured with an
-*absolute* `plugin_system.plugins_directory` (a supported value -- see
-CLAUDE.md) hit `UnboundLocalError` importing web_interface.app at all, taking
-the whole web UI down.
-
-app.py isn't imported directly by the test suite -- it has real side effects
-(managers, background state) at import time -- so this extracts the exact
-resolution block by its stable comment markers and executes it in isolation,
-the same way the rest of the suite validates generated/templated code rather
-than re-implementing it.
-"""
-from pathlib import Path
-
-APP_PY = Path(__file__).resolve().parent.parent / "web_interface/app.py"
-
-START_MARKER = "# Resolve plugin directory - handle both absolute and relative paths\n"
-END_MARKER = "\nplugin_manager = PluginManager("
-
-
-def _resolution_block() -> str:
-    src = APP_PY.read_text()
-    start = src.index(START_MARKER)
-    end = src.index(END_MARKER, start)
-    return src[start:end]
-
-
-def test_resolution_block_still_matches_expected_markers():
-    """If app.py is restructured enough that these markers move, the exec
-    below would silently test nothing -- fail loudly instead."""
-    block = _resolution_block()
-    assert "plugins_dir" in block and "os.path.isabs" in block
-
-
-def test_absolute_plugins_directory_does_not_raise_unboundlocalerror():
-    import os
-    ns = {"os": os, "Path": Path, "__file__": str(APP_PY),
-          "plugins_dir_name": "/opt/ledmatrix-plugins"}
-    exec(compile(_resolution_block(), str(APP_PY), "exec"), ns)  # noqa: S102
-    assert ns["project_root"] == APP_PY.parent.parent
-    assert ns["plugins_dir"] == Path("/opt/ledmatrix-plugins")
-
-
-def test_relative_plugins_directory_still_resolves_under_project_root():
-    import os
-    ns = {"os": os, "Path": Path, "__file__": str(APP_PY),
-          "plugins_dir_name": "plugin-repos"}
-    exec(compile(_resolution_block(), str(APP_PY), "exec"), ns)  # noqa: S102
-    assert ns["plugins_dir"] == ns["project_root"] / "plugin-repos"

test/test_cache_nonfinite_floats.py

@@ -0,0 +1,158 @@
+"""Non-finite floats round-trip identically with and without orjson.
+
+JSON has no NaN or Infinity. The stdlib emits them anyway as an extension;
+orjson refuses to and writes null. Cache files outlive the decision of which
+encoder is installed, so both halves of that gap are pinned here:
+
+  * writing -- installing orjson must not silently change what gets cached,
+    so the stdlib path writes null too;
+  * reading -- records already on disk carrying NaN or Infinity must stay
+    readable, or installing orjson turns each of them into a "corrupted cache
+    file" that DiskCache.get logs as an error and deletes.
+"""
+
+import importlib
+import json
+import math
+import sys
+from pathlib import Path
+from unittest import mock
+
+import pytest
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from src.cache import disk_cache as disk_cache_module  # noqa: E402
+
+
+@pytest.fixture
+def stdlib_cache():
+    """The module as it loads on a host with no orjson wheel."""
+    # A None entry in sys.modules makes `import orjson` raise ImportError,
+    # which is the branch we want, whether or not orjson is really installed.
+    with mock.patch.dict(sys.modules, {"orjson": None}):
+        module = importlib.reload(disk_cache_module)
+        assert module.orjson is None
+        yield module
+    importlib.reload(disk_cache_module)
+
+
+@pytest.fixture
+def orjson_cache():
+    """The module as it loads with orjson available."""
+    module = importlib.reload(disk_cache_module)
+    if module.orjson is None:
+        pytest.skip("orjson is not installed on this host")
+    return module
+
+
+NON_FINITE = {"nan": float("nan"), "inf": float("inf"), "ninf": float("-inf")}
+
+
+def _reject_constant(name):
+    """Make json.loads as strict as orjson about NaN/Infinity tokens."""
+    raise AssertionError(f"non-spec JSON constant in output: {name}")
+
+
+class TestWritePolicy:
+    """Non-finite floats become null on whichever encoder is in use."""
+
+    def _assert_nulled(self, module):
+        record = module._loads(module._dumps(dict(NON_FINITE, ok=1.5)))
+        assert record["nan"] is None
+        assert record["inf"] is None
+        assert record["ninf"] is None
+        # Finite values are untouched.
+        assert record["ok"] == 1.5
+
+    def test_stdlib_writes_null(self, stdlib_cache):
+        self._assert_nulled(stdlib_cache)
+
+    def test_orjson_writes_null(self, orjson_cache):
+        self._assert_nulled(orjson_cache)
+
+    def test_stdlib_emits_spec_compliant_json(self, stdlib_cache):
+        # The point of the write half: bytes written without orjson must still
+        # parse once orjson is installed later. json.loads accepts the
+        # extension tokens, so it cannot show this -- assert on the bytes, and
+        # on a strict reader when there is one.
+        raw = stdlib_cache._dumps(dict(NON_FINITE))
+        assert b"NaN" not in raw
+        assert b"Infinity" not in raw
+        assert json.loads(raw, parse_constant=_reject_constant) == {
+            "nan": None, "inf": None, "ninf": None}
+
+    def test_nested_non_finite_are_replaced(self, stdlib_cache):
+        data = {"a": [1.0, float("nan"), {"b": float("inf")}], "c": (float("-inf"),)}
+        record = stdlib_cache._loads(stdlib_cache._dumps(data))
+        assert record["a"] == [1.0, None, {"b": None}]
+        assert record["c"] == [None]
+
+    def test_finite_payloads_are_byte_identical_to_the_old_encoder(self, stdlib_cache):
+        # allow_nan=False must not change ordinary output.
+        data = {"x": 1, "y": [1.5, "s", True, None], "z": {"k": 2.25}}
+        assert stdlib_cache._dumps(data) == json.dumps(
+            data, cls=stdlib_cache.DateTimeEncoder).encode("utf-8")
+
+
+class TestReplaceNonFinite:
+    def test_leaves_ordinary_values_alone(self):
+        for value in (1, 1.5, "s", True, None, [], {}):
+            assert disk_cache_module._replace_nonfinite(value) == value
+
+    def test_replaces_every_non_finite_float(self):
+        for value in NON_FINITE.values():
+            assert disk_cache_module._replace_nonfinite(value) is None
+
+    def test_walks_nested_containers(self):
+        assert disk_cache_module._replace_nonfinite(
+            {"a": [{"b": float("nan")}]}) == {"a": [{"b": None}]}
+
+
+class TestLegacyRecordsStayReadable:
+    """Files written before orjson arrived still load."""
+
+    LEGACY = b'{"timestamp": 1000.0, "value": NaN, "other": Infinity}'
+
+    def test_stdlib_reads_legacy_tokens(self, stdlib_cache):
+        record = stdlib_cache._loads(self.LEGACY)
+        assert math.isnan(record["value"])
+        assert math.isinf(record["other"])
+
+    def test_orjson_falls_back_for_legacy_tokens(self, orjson_cache):
+        record = orjson_cache._loads(self.LEGACY)
+        assert math.isnan(record["value"])
+        assert math.isinf(record["other"])
+
+    def test_genuinely_malformed_files_still_raise(self, stdlib_cache):
+        with pytest.raises(json.JSONDecodeError):
+            stdlib_cache._loads(b'{"a": ')
+
+    def test_orjson_still_raises_for_malformed_files(self, orjson_cache):
+        with pytest.raises(json.JSONDecodeError):
+            orjson_cache._loads(b'{"a": ')
+
+
+class TestDiskCacheEndToEnd:
+    def _cache(self, module, tmp_path):
+        return module.DiskCache(str(tmp_path))
+
+    def test_legacy_file_is_not_deleted_as_corrupt(self, orjson_cache, tmp_path):
+        cache = self._cache(orjson_cache, tmp_path)
+        path = cache.get_cache_path("legacy")
+        Path(path).write_bytes(
+            b'{"timestamp": %d, "value": NaN}' % int(__import__("time").time()))
+
+        record = cache.get("legacy", max_age=None)
+
+        assert record is not None, "legacy NaN record was treated as corrupt"
+        assert math.isnan(record["value"])
+        assert Path(path).exists(), "legacy NaN record was deleted"
+
+    def test_round_trip_through_set_and_get(self, stdlib_cache, tmp_path):
+        cache = self._cache(stdlib_cache, tmp_path)
+        cache.set("k", {"timestamp": __import__("time").time(),
+                        "value": float("nan")})
+        record = cache.get("k", max_age=None)
+        assert record is not None
+        assert record["value"] is None

test/test_composer_blueprint_registered.py

@@ -1,64 +0,0 @@
-"""composer_bp must actually be registered on the Flask app.
-
-web_interface/blueprints/composer.py defines a full blueprint -- the
-/composer/ page, /composer/api/generate, /composer/api/install, etc. -- but
-nothing in web_interface/app.py imported or registered it. pages_v3 and
-api_v3 both go through the same "import, wire managers, register_blueprint"
-sequence; composer_bp had none of the three. The routes existed and worked
-in isolation (every other composer test builds its own minimal Flask app
-and registers composer_bp directly), but in the real running app every
-composer URL -- including the page itself -- was a 404, and the frontend's
-hardcoded '/composer/api/...' fetches (composer-app.js) had nothing to
-reach.
-
-app.py has import-time side effects (it loads config, builds managers, and
-in some configurations starts background threads), so this scans the source
-text rather than importing the module -- the same approach already used for
-test_composer_js_contracts.py's structural checks.
-"""
-import re
-from pathlib import Path
-
-APP_PY = Path(__file__).resolve().parent.parent / "web_interface" / "app.py"
-
-
-def _source() -> str:
-    return APP_PY.read_text()
-
-
-def test_composer_blueprint_is_imported():
-    src = _source()
-    assert re.search(
-        r"from web_interface\.blueprints\.composer import composer_bp", src
-    ), "app.py never imports composer_bp"
-
-
-def test_composer_blueprint_is_registered_under_composer_prefix():
-    src = _source()
-    match = re.search(
-        r"app\.register_blueprint\(\s*composer_bp\s*,\s*url_prefix\s*=\s*"
-        r"['\"](?P<prefix>[^'\"]*)['\"]",
-        src,
-    )
-    assert match, "app.py never calls app.register_blueprint(composer_bp, ...)"
-    # composer.html and composer-app.js hardcode '/composer/api/...' and
-    # '/composer/api/fonts/...' -- any other prefix serves a page whose own
-    # fetches and @font-face all 404.
-    assert match.group("prefix") == "/composer"
-
-
-def test_composer_blueprint_managers_are_wired_before_registration():
-    """Registered with no managers set means every route 503s or crashes.
-
-    composer.py initialises config_manager/plugin_manager/plugins_dir/
-    project_root to None at import time specifically so app.py can set them
-    -- the same pattern api_v3 and pages_v3 use.
-    """
-    src = _source()
-    register_match = re.search(r"app\.register_blueprint\(\s*composer_bp", src)
-    assert register_match, "app.py never registers composer_bp"
-    before_registration = src[: register_match.start()]
-    for attr in ("config_manager", "plugin_manager", "plugins_dir", "project_root"):
-        assert re.search(rf"composer_bp\.{attr}\s*=", before_registration), (
-            f"composer_bp.{attr} is never set before registration"
-        )

test/test_composer_code_injection.py

@@ -1,323 +0,0 @@
-"""The composer generates Python that the plugin loader imports and executes.
-
-/api/install writes the generated manager.py into plugins_dir and the loader
-imports it, so anything the payload can splice into that source runs on the
-device. The ast.parse check in _generate_plugin_files rejects only *invalid*
-syntax -- an injected `import os` is perfectly valid and passed it.
-
-Two ways in, both confirmed against the code before it was fixed:
-
-  metadata.name = a name containing a triple-quote, a newline, then
-                  `import os; PWNED = os.getuid()`, then another triple-quote
-      -> closes the module docstring; the rest became module-level statements
-         (spelled out rather than shown literally -- writing the payload into
-         this docstring closes *this* file's docstring, which is the bug)
-
-  element x     = '0 or __import__("os").system("id")'
-      -> f-string interpolated it verbatim: x=0 or __import__("os").system("id")
-"""
-import ast
-import re
-import sys
-from pathlib import Path
-
-import pytest
-
-sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
-
-from web_interface.blueprints import composer as C  # noqa: E402
-
-BASE_META = {"id": "test-plugin", "name": "Clock", "author": "a",
-             "version": "1.0.0", "description": "d"}
-
-#: Values that terminate a Python expression and start a new statement.
-EXPR_PAYLOADS = [
-    '0 or __import__("os").system("id")',
-    '0);import os;os.system("id");(',
-    '__import__("subprocess").run(["id"])',
-    "0 if False else exec('x=1')",
-    "1e999", "nan", "0x41", "0__0",
-]
-
-#: Values that close a string literal in the generated source.
-LITERAL_PAYLOADS = [
-    'Clock"""\nimport os; PWNED = os.getuid()\n"""',
-    "Clock'''\nimport os\n'''",
-    'Clock" + __import__("os").system("id") + "',
-    "Clock\\", "Clock\nimport os",
-]
-
-
-def _payload(**over):
-    # dataModel.configVars is the key _generate_plugin_files reads; "config_vars"
-    # was never looked at, so anything passed through it tested nothing.
-    p = {"metadata": dict(BASE_META), "elements": [],
-         "dataModel": {"configVars": over.pop("config_vars", [])}}
-    p["metadata"].update(over.pop("metadata", {}))
-    p.update(over)
-    return p
-
-
-def _generated(payload):
-    return C._generate_plugin_files(payload)["manager.py"]
-
-
-def _module_level_code(src):
-    """Statements at module level that are not the docstring/imports/classes."""
-    tree = ast.parse(src)
-    out = []
-    for node in tree.body:
-        if isinstance(node, (ast.ClassDef, ast.FunctionDef, ast.ImportFrom, ast.Import)):
-            continue
-        if isinstance(node, ast.Expr) and isinstance(node.value, ast.Constant):
-            continue  # the docstring
-        out.append(ast.unparse(node))
-    return out
-
-
-@pytest.mark.parametrize("payload", LITERAL_PAYLOADS)
-def test_a_name_that_breaks_out_of_a_literal_is_refused(payload):
-    with pytest.raises(C.ComposerInputError):
-        _generated(_payload(metadata={"name": payload}))
-
-
-#: Types with a drawing branch in manager.py.j2. An injection test using any
-#: other type proves nothing: _preprocess_elements drops it, so its values
-#: never reach the generated source and every assertion passes trivially.
-#: This test previously used "line", which has never had a branch.
-RENDERED_GEOMETRY_CASES = [
-    ("rectangle", {"x": 0, "y": 0, "width": 10, "height": 8}),
-    ("arc", {"x": 0, "y": 0, "width": 24, "height": 24}),
-    ("ellipse", {"x": 0, "y": 0, "width": 24, "height": 12}),
-    ("rounded_rectangle", {"x": 0, "y": 0, "width": 24, "height": 10}),
-    ("gauge", {"x": 0, "y": 0, "width": 32, "height": 32}),
-]
-
-
-@pytest.mark.parametrize("etype,base", RENDERED_GEOMETRY_CASES)
-@pytest.mark.parametrize("evil", EXPR_PAYLOADS)
-@pytest.mark.parametrize("field", ["x", "y", "width", "height"])
-def test_a_non_numeric_geometry_value_cannot_reach_the_source(etype, base, evil, field):
-    """width/height were interpolated raw into the generated source.
-
-    p['x2_expr'] = f"({x_expr}) + {w}" with w straight off the payload, so a
-    rectangle with width='0 or __import__("os").system("id")' produced
-
-        [0, 0, (0) + 0 or __import__("os").system("id"), (0) + 8],
-
-    in a manager.py that /api/install writes to disk and the loader imports.
-    """
-    el = {"type": etype, "id": "e1", **base}
-    el[field] = evil
-    src = _generated(_payload(elements=[el]))
-    assert "__import__" not in src, f"{etype}.{field}={evil!r} reached the generated source"
-    assert "os.system" not in src
-    assert not _module_level_code(src), \
-        f"{etype}.{field}={evil!r} produced module-level statements: {_module_level_code(src)}"
-
-
-def test_every_injection_case_uses_a_type_that_actually_renders():
-    """Guards against the whole suite quietly going vacuous again.
-
-    An element type with no template branch is dropped before generation, so
-    an injection test written against one asserts nothing and still passes.
-    """
-    used = {etype for etype, _ in RENDERED_GEOMETRY_CASES}
-    missing = used - set(C._RENDERABLE_ELEMENT_TYPES)
-    assert not missing, f"injection tests use non-rendering types: {sorted(missing)}"
-
-
-@pytest.mark.parametrize("evil", EXPR_PAYLOADS)
-@pytest.mark.parametrize("channel", ["r", "g", "b"])
-def test_a_non_numeric_colour_channel_cannot_reach_the_source(evil, channel):
-    el = {"type": "text", "id": "t1", "x": 0, "y": 0, "text": "hi",
-          "font": "press_start", "r": 255, "g": 255, "b": 255}
-    el[channel] = evil
-    src = _generated(_payload(elements=[el]))
-    assert "__import__" not in src and "os.system" not in src
-    assert not _module_level_code(src)
-
-
-def test_colour_channels_are_clamped_to_a_byte():
-    el = {"type": "text", "id": "t1", "x": 0, "y": 0, "text": "hi",
-          "font": "press_start", "r": 99999, "g": -5, "b": 128}
-    src = _generated(_payload(elements=[el]))
-    assert "(255, 0, 128)" in src, "channels were not clamped to 0-255"
-
-
-#: fillR/fillG/fillB (and outR/G/B, bgR/G/B, trackR/G/B) go through
-#: _as_fill_filter -> _as_rgb_filter, a separate path from _rgb_expr above.
-#: It used raw int() until it was found to raise ValueError on a non-numeric
-#: channel instead of clamping like every other coerced value in this module.
-@pytest.mark.parametrize("evil", EXPR_PAYLOADS)
-@pytest.mark.parametrize("channel", ["fillR", "fillG", "fillB"])
-def test_a_non_numeric_fill_channel_cannot_reach_the_source(evil, channel):
-    el = {"type": "rectangle", "id": "r1", "x": 0, "y": 0, "width": 10, "height": 8,
-          "fillR": 0, "fillG": 0, "fillB": 128}
-    el[channel] = evil
-    src = _generated(_payload(elements=[el]))
-    assert "__import__" not in src and "os.system" not in src
-    assert not _module_level_code(src)
-
-
-def test_fill_channels_are_clamped_to_a_byte():
-    el = {"type": "rectangle", "id": "r1", "x": 0, "y": 0, "width": 10, "height": 8,
-          "fillR": 99999, "fillG": -5, "fillB": 128}
-    src = _generated(_payload(elements=[el]))
-    assert "(255, 0, 128)" in src, "fill channels were not clamped to 0-255"
-
-
-def test_the_generated_module_still_has_no_top_level_statements():
-    """The clean case: a normal payload produces only imports and a class."""
-    el = {"type": "text", "id": "t1", "x": 4, "y": 4, "text": "hi",
-          "font": "press_start", "r": 1, "g": 2, "b": 3}
-    src = _generated(_payload(elements=[el]))
-    assert not _module_level_code(src)
-    assert "(1, 2, 3)" in src
-
-
-# --- config variable keys ---------------------------------------------------
-
-def _with_key(key):
-    return {"metadata": dict(BASE_META), "elements": [],
-            "dataModel": {"configVars": [{"key": key, "type": "string",
-                                          "default": "x", "label": "L"}]}}
-
-
-@pytest.mark.parametrize("key", ["class", "def", "import", "None", "True",
-                                 "lambda", "pass", "match", "case"])
-def test_a_keyword_config_key_is_named_in_the_error(key):
-    """ast.parse already rejected these, but as an unhelpful line number.
-
-    "Generated code has a syntax error: invalid syntax (line 17)" tells the
-    user nothing about which field to fix.
-    """
-    with pytest.raises(C.ComposerInputError) as exc:
-        _generated(_with_key(key))
-    assert key in str(exc.value) and "keyword" in str(exc.value).lower()
-
-
-@pytest.mark.parametrize("key", ["config", "logger", "display_manager",
-                                 "cache_manager", "plugin_id", "enabled",
-                                 "self", "update", "display"])
-def test_a_reserved_attribute_config_key_is_refused(key):
-    """These generate *valid* Python that silently clobbers plugin state.
-
-    The worst is `config`: the assignment lands right after super().__init__(),
-    so `self.config = config.get("config", "x")` replaces the plugin's config
-    dict with a string and every later self.config.get(...) fails at runtime.
-    """
-    with pytest.raises(C.ComposerInputError) as exc:
-        _generated(_with_key(key))
-    assert key in str(exc.value) and "reserved" in str(exc.value).lower()
-
-
-@pytest.mark.parametrize("key", ["brightness", "my_var", "_private", "x1",
-                                 "update_interval_seconds"])
-def test_ordinary_config_keys_are_still_accepted(key):
-    src = _generated(_with_key(key))
-    assert f"self.{key} = config.get(" in src
-
-
-def test_the_generated_config_assignment_does_not_precede_super_init():
-    """Guards the reasoning behind the reserved list, not just the list."""
-    src = _generated(_with_key("brightness"))
-    body = src.splitlines()
-    super_at = next(i for i, line in enumerate(body) if "super().__init__(" in line)
-    assign_at = next(i for i, line in enumerate(body)
-                     if "self.brightness = config.get(" in line)
-    assert assign_at > super_at, (
-        "config vars are assigned before super().__init__(); the reserved-name "
-        "list assumes they land after it")
-
-
-# --- optional keys ----------------------------------------------------------
-
-@pytest.mark.parametrize("el_type,missing", [
-    ("text", "text"), ("text", "text2"), ("clock", "format"),
-])
-def test_an_element_missing_an_optional_key_does_not_500(el_type, missing):
-    """`p` is a copy of the raw element, so an absent key stays absent.
-
-    The defaults were applied to locals only, so manager.py.j2 rendered
-    `{{ el.text | tojson }}` over a jinja2.Undefined and tojson raised
-    TypeError -- which no handler catches, making a missing key a 500 rather
-    than a validation error or a sensible default.
-    """
-    el = {"type": el_type, "id": "e1", "x": 0, "y": 0, "font": "press_start"}
-    src = _generated(_payload(elements=[el]))
-    ast.parse(src)          # must still be valid Python
-    assert "Undefined" not in src
-
-
-def test_a_clock_without_a_format_uses_the_documented_default():
-    el = {"type": "clock", "id": "c1", "x": 0, "y": 0, "font": "press_start"}
-    src = _generated(_payload(elements=[el]))
-    assert '"%H:%M"' in src, "the %H:%M default did not reach the generated source"
-
-
-#: (element type, channel key, base element) for colour channels that were
-#: interpolated raw rather than through _rgb_expr/_safe_int. Prefixed channels
-#: (emptyR/G/B, labelR/G/B) were the ones the original r/g/b test never reached.
-RAW_COLOUR_CASES = [
-    ("progress_bar", "r",      {"x": 0, "y": 0}),
-    ("progress_bar", "g",      {"x": 0, "y": 0}),
-    ("pips",         "b",      {"x": 0, "y": 0}),
-    ("pips",         "emptyR", {"x": 0, "y": 0}),
-    ("pips",         "emptyG", {"x": 0, "y": 0}),
-    ("sparkline",    "r",      {"x": 0, "y": 0}),
-    ("gauge",        "labelR", {"x": 0, "y": 0, "width": 32, "height": 32}),
-    ("gauge",        "labelB", {"x": 0, "y": 0, "width": 32, "height": 32}),
-]
-
-
-@pytest.mark.parametrize("etype,channel,base", RAW_COLOUR_CASES)
-@pytest.mark.parametrize("evil", EXPR_PAYLOADS)
-def test_a_prefixed_colour_channel_cannot_reach_the_source(etype, channel, base, evil):
-    """Five tuples were built with f"({el.get('r', 100)}, ...)" -- no coercion.
-
-    The pre-existing colour test only covered r/g/b on a text element, so the
-    prefixed channels and the four other types were never exercised.
-    """
-    el = {"type": etype, "id": "e1", **base}
-    el[channel] = evil
-    src = _generated(_payload(elements=[el]))
-    assert "__import__" not in src, f"{etype}.{channel}={evil!r} reached the source"
-    assert "os.system" not in src
-    assert not _module_level_code(src)
-
-
-@pytest.mark.parametrize("value", [float("inf"), float("-inf"), float("nan")])
-@pytest.mark.parametrize("field", ["x", "y", "width", "height"])
-def test_a_non_finite_dimension_does_not_escape_as_an_unhandled_error(field, value):
-    """json.loads accepts Infinity/NaN and Flask passes them through, so a
-    payload can hand _safe_int a non-finite float. int(inf) raises
-    OverflowError -- neither ValueError nor ComposerInputError -- so it escaped
-    both handlers and surfaced as a 500 with a traceback instead of a 422."""
-    el = {"type": "rectangle", "id": "r1", "x": 0, "y": 0, "width": 10, "height": 8}
-    el[field] = value
-    src = _generated(_payload(elements=[el]))       # must not raise
-    # A non-finite value must be replaced by the default, not spelled into the
-    # source. Word-boundary match: "info" in self.logger.info contains "inf".
-    assert not re.search(r"\b(inf|nan|Infinity|NaN)\b", src), \
-        f"{field}={value!r} leaked a non-finite literal into the source"
-    assert not _module_level_code(src)
-
-
-@pytest.mark.parametrize("bad_id", [
-    'x = __import__("os").system("id") #',
-    "x\nimport os\n_y",
-    "x[0]",
-    "",
-    "a" * 200,
-])
-def test_a_marquee_id_cannot_become_code(bad_id):
-    """data_key is spliced UNQUOTED into variable names
-    (_{{ data_key }}_text = ...), so a non-identifier id landed in the source
-    as code. ast.parse caught it, but the caller then got an opaque
-    "Generated code has a syntax error" rather than being told the id is bad."""
-    el = {"type": "marquee", "id": bad_id, "x": 0, "y": 0, "text": "hi"}
-    src = _generated(_payload(elements=[el]))       # must not raise
-    assert "__import__(" not in src
-    assert "os.system(" not in src
-    assert not _module_level_code(src)

test/test_composer_empty_block.py

@@ -1,124 +0,0 @@
-"""An element the template cannot draw must not produce an empty `if` block.
-
-manager.py.j2 wraps each element in `if width >= N:` (breakpoint) and/or
-`if int(time.time() * 2) % 2:` (blink), and the body comes from the per-type
-branches. A type with no branch contributed nothing, so the wrapper opened a
-block with no statements in it. ast.parse in _generate_plugin_files then
-failed and the caller was told only:
-
-    Generated code has a syntax error: expected an indented block after
-    'if' statement on line 49
-
-which names a line of generated source the user never sees. Confirmed against
-the code before the fix with a `group` element carrying minWidth.
-
-Two defences, both covered here: _preprocess_elements drops types the template
-has no branch for, and the template emits a `pass` fallback so a type added to
-the canvas before its branch exists degrades to a no-op instead of a broken
-plugin.
-"""
-import ast
-import re
-import sys
-from pathlib import Path
-
-import pytest
-
-sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
-
-from web_interface.blueprints import composer as C  # noqa: E402
-
-TEMPLATE = (Path(__file__).resolve().parent.parent
-            / "web_interface/templates/v3/composer/manager.py.j2")
-
-BASE_META = {"id": "test-plugin", "name": "Clock", "author": "a",
-             "version": "1.0.0", "description": "d"}
-
-
-def generate(element):
-    return C._generate_plugin_files({
-        "metadata": BASE_META,
-        "elements": [element],
-        "dataModel": {"configVars": []},
-    })
-
-
-@pytest.mark.parametrize("wrapper", [
-    {"minWidth": 64},          # breakpoint block
-    {"blink": True},           # blink block
-    {"minWidth": 64, "blink": True},   # both, nested
-])
-@pytest.mark.parametrize("etype", ["group", "widget_9000", "section"])
-def test_undrawable_element_does_not_break_generation(etype, wrapper):
-    element = {"type": etype, "x": 0, "y": 0, "color": "#ffffff", **wrapper}
-    files = generate(element)          # must not raise ComposerInputError
-    assert "manager.py" in files
-
-
-def test_drawable_element_still_renders_inside_a_breakpoint():
-    files = generate({"type": "text", "text": "hi", "x": 0, "y": 0,
-                      "minWidth": 64, "color": "#ffffff"})
-    src = files["manager.py"]
-    assert "if width >= 64:" in src
-    assert "draw_text" in src
-
-
-def test_renderable_types_match_the_template_branches():
-    """The constant and the template must agree.
-
-    A type listed in the constant with no branch emits an empty block (the bug
-    above); a type with a branch but missing from the constant is silently
-    dropped from every generated plugin. Neither is visible without this check.
-    """
-    branches = set(re.findall(r"el\.type == '([a-z_]+)'", TEMPLATE.read_text()))
-    assert branches == set(C._RENDERABLE_ELEMENT_TYPES)
-
-
-def test_template_closes_the_branch_chain_with_a_fallback():
-    """Belt and braces: even if the constant drifts, no empty block escapes."""
-    text = TEMPLATE.read_text()
-    assert "{% else %}" in text
-    assert "pass  # element type" in text
-
-
-@pytest.mark.parametrize("wrapper", [
-    {"minWidth": 64},
-    {"blink": True},
-    {"minWidth": 64, "blink": True},
-])
-def test_dynamic_text_with_non_config_binding_does_not_break_generation(wrapper):
-    """dynamic_text only renders a body for binding.source == 'config'.
-
-    _preprocess_elements accepts any string as binding.source (it just
-    defaults a missing one to 'config'), so a 'live' or 'sensor' source --
-    anything a client sends that isn't literally 'config' -- hit the same
-    empty-if-block bug as an undrawable element type, just one level deeper:
-    the branch is taken, but its own inner `if` produced nothing.
-    """
-    element = {"type": "dynamic_text", "x": 0, "y": 0, "color": "#ffffff",
-               "binding": {"source": "live", "key": "temperature"}, **wrapper}
-    files = generate(element)          # must not raise ComposerInputError
-    assert "manager.py" in files
-    assert "non-config dynamic_text binding draws nothing" in files["manager.py"]
-
-
-def test_binding_source_cannot_break_out_of_the_comment_it_lands_in():
-    """binding.source used to be interpolated straight into a Python comment
-    (`pass  # dynamic_text binding_source "{{ el.binding_source }}" draws
-    nothing`) with no escaping. A source string carrying a newline closed the
-    comment, and text on the following line(s), indented to match, became a
-    real statement in the generated plugin -- CWE-94, and live once
-    composer_bp was registered (confirmed: this exact payload produces a
-    manager.py containing a clean, ast.parse-valid `import os` against the
-    pre-fix template). The comment is now a fixed literal that never
-    interpolates the value at all.
-    """
-    payload = "foo\n            import os\n            os.system('id')  # "
-    element = {"type": "dynamic_text", "x": 0, "y": 0, "color": "#ffffff",
-               "binding": {"source": payload, "key": "temperature"}}
-    files = generate(element)
-    src = files["manager.py"]
-    assert "import os" not in src
-    assert "os.system" not in src
-    assert "non-config dynamic_text binding draws nothing" in src
-    ast.parse(src)          # belt and braces: generate() already enforces this

test/test_composer_js_contracts.py

@@ -1,263 +0,0 @@
-"""Structural checks on the composer's JavaScript.
-
-There is no JS test runner in this repo, but three defects here are structural
-enough to assert on the parse tree, and each was a real bug:
-
-- Stroke widths inside _drawElement were left in canvas pixels while the
-  geometry around them scaled by SCALE, so at SCALE>1 every outline rendered
-  thinner than one LED pixel and the preview stopped matching the panel.
-- The `line` branch drew raw el.x0/el.y0/el.x1/el.y1, ignoring the anchor that
-  every other element type honours, so setting xAnchor moved everything except
-  lines -- and getBoundingBox had the same omission, leaving the hit box behind.
-- Four methods mutated exactly what _snapshot() serialises (metadata,
-  currentPreset) without calling it. _snapshot is the only caller of
-  _debouncedAutosave, so those changes were lost on reload and could not be
-  undone.
-"""
-import re
-from pathlib import Path
-
-import pytest
-
-tree_sitter = pytest.importorskip("tree_sitter")
-tree_sitter_javascript = pytest.importorskip("tree_sitter_javascript")
-
-JS_DIR = Path(__file__).resolve().parent.parent / "web_interface/static/v3/js/composer"
-CANVAS = JS_DIR / "composer-canvas.js"
-APP = JS_DIR / "composer-app.js"
-
-
-def _function_source(path: Path, name: str) -> str:
-    """Return the source of a top-level function declaration by name."""
-    src = path.read_bytes()
-    lang = tree_sitter.Language(tree_sitter_javascript.language())
-    tree = tree_sitter.Parser(lang).parse(src)
-    found = []
-
-    def walk(node):
-        if node.type == "function_declaration":
-            ident = node.child_by_field_name("name")
-            if ident is not None and src[ident.start_byte:ident.end_byte].decode() == name:
-                found.append(src[node.start_byte:node.end_byte].decode())
-        for c in node.children:
-            walk(c)
-
-    walk(tree.root_node)
-    assert found, f"{name} not found in {path.name}"
-    return found[0]
-
-
-def _method_source(path: Path, name: str) -> str:
-    """Return the source of a top-level object method by name."""
-    src = path.read_bytes()
-    lang = tree_sitter.Language(tree_sitter_javascript.language())
-    tree = tree_sitter.Parser(lang).parse(src)
-    found = []
-
-    def walk(node):
-        if node.type == "method_definition":
-            ident = node.child_by_field_name("name")
-            if ident is not None and src[ident.start_byte:ident.end_byte].decode() == name:
-                found.append(src[node.start_byte:node.end_byte].decode())
-        for c in node.children:
-            walk(c)
-
-    walk(tree.root_node)
-    assert found, f"{name} not found in {path.name}"
-    return found[0]
-
-
-def test_both_files_parse():
-    lang = tree_sitter.Language(tree_sitter_javascript.language())
-    parser = tree_sitter.Parser(lang)
-    for path in (CANVAS, APP):
-        tree = parser.parse(path.read_bytes())
-        errors = []
-
-        def walk(node):
-            if node.type == "ERROR" or node.is_missing:
-                errors.append(node.start_point[0] + 1)
-            for c in node.children:
-                walk(c)
-
-        walk(tree.root_node)
-        assert not errors, f"{path.name} has parse errors at lines {errors}"
-
-
-def test_element_strokes_scale_with_scale():
-    """No bare `ctx.lineWidth = 1` inside _drawElement.
-
-    Selection handles and the grid are drawn in canvas pixels deliberately and
-    live in other functions, so this is scoped to the element drawing routine.
-    """
-    body = _function_source(CANVAS, "_drawElement")
-    offenders = re.findall(r"ctx\.lineWidth\s*=\s*1\s*;", body)
-    assert not offenders, f"{len(offenders)} unscaled stroke width(s) in _drawElement"
-
-
-def test_line_branch_applies_the_anchor_offset():
-    """Scoped to _drawElement.
-
-    getBoundingBox has its own `case 'line': {` and appears first in the file,
-    so searching the whole text found *that* branch -- this assertion passed
-    with the draw branch's anchor offset removed. Verified: stripping it and
-    re-running gave 11/11 green.
-    """
-    body = _function_source(CANVAS, "_drawElement")
-    line_branch = body[body.index("case 'line': {"):]
-    line_branch = line_branch[:line_branch.index("case 'divider'")]
-    assert "ax - el.x0" in line_branch and "ay - el.y0" in line_branch, \
-        "line drawing ignores xAnchor/yAnchor"
-    assert "moveTo(el.x0 * s" not in line_branch, \
-        "line still drawn from unanchored endpoints"
-
-
-def test_line_bounding_box_applies_the_anchor_offset():
-    """The companion to the above: scoped to getBoundingBox specifically, so
-    the two tests cannot both be satisfied by the same branch."""
-    body = _function_source(CANVAS, "getBoundingBox")
-    box = body[body.index("case 'line'"):]
-    box = box[:box.index("case 'divider'")]
-    assert "ax - el.x0" in box, "line bounding box ignores the anchor"
-
-
-@pytest.mark.parametrize("method", [
-    "onBgColorChange",     # mutates metadata.bgColor
-    "setCustomSize",       # mutates currentPreset / MATRIX_W / MATRIX_H
-    "changePreset",        # mutates currentPreset / MATRIX_W / MATRIX_H
-    "applyPresetLabel",    # same, for sizes not in DISPLAY_PRESETS
-    "onColorChange",       # the one that was already fixed — keeps it fixed
-])
-def test_state_mutations_take_a_snapshot(method):
-    body = _method_source(APP, method)
-    assert "_snapshot()" in body, \
-        f"{method} changes snapshotted state without calling _snapshot()"
-    assert "isDirty = true" in body, f"{method} does not mark the design dirty"
-
-
-@pytest.mark.parametrize("method", ["changePreset", "applyPresetLabel"])
-def test_restore_path_stays_snapshot_free(method):
-    """_applyState and loadTemplate call these with {silent: true} while
-    restoring; snapshotting there would push restore steps onto the undo stack
-    and re-autosave the state just loaded."""
-    body = _method_source(APP, method)
-    assert "opts.silent" in body, f"{method} lost its silent guard"
-    snap = body.index("_snapshot()")
-    guard = body.index("!opts.silent")
-    assert guard < snap, f"{method} snapshots outside the !opts.silent guard"
-
-
-TEMPLATE_HTML = (Path(__file__).resolve().parent.parent
-                 / "web_interface/templates/v3/composer.html")
-
-#: The six toolbar buttons and the wrapper each must call.
-ALIGN_BUTTONS = ["alignLeft", "alignHCenter", "alignRight",
-                 "alignTop", "alignVCenter", "alignBottom"]
-
-
-def test_alignment_buttons_use_the_anchor_clearing_path():
-    """Two alignment implementations existed and the toolbar used the wrong one.
-
-    The legacy alignElement(dir) set el.x/el.y but left xAnchor/yAnchor in
-    place. resolveAnchor turns anchor='right' into `dim - val`, so "align left"
-    (el.x = 0) resolved to x = MATRIX_W -- the element jumped to the far right
-    edge instead. _alignElement clears the anchor first, so the stored value is
-    absolute, and it also updates el.x0/el.y0 so lines actually move.
-    """
-    html = TEMPLATE_HTML.read_text()
-    for wrapper in ALIGN_BUTTONS:
-        assert f"{wrapper}()" in html, f"toolbar does not call {wrapper}()"
-    assert not re.search(r"[^_]alignElement\(", html), \
-        "toolbar still calls the legacy alignElement()"
-
-
-def test_the_legacy_alignelement_is_gone():
-    """Leaving it in place invites the toolbar drifting back to it."""
-    src = APP.read_text()
-    assert not re.search(r"^\s{4}alignElement\(dir\)", src, re.M), \
-        "legacy alignElement(dir) still defined"
-
-
-def test_align_clears_the_anchor_and_moves_line_endpoints():
-    body = _method_source(APP, "_alignElement")
-    assert "xAnchor = null" in body and "yAnchor = null" in body, \
-        "_alignElement no longer clears the anchor, so aligning an anchored " \
-        "element resolves to the wrong edge"
-    assert "el.x0" in body and "el.y0" in body, \
-        "_alignElement no longer moves line endpoints"
-
-
-def test_align_translates_both_line_endpoints_not_just_the_start():
-    """Setting only x0 (or y0) left x1/y1 behind, so aligning a line changed
-    its shape instead of moving it -- e.g. a line from x0=20 to x1=50 aligned
-    right became x0=98, x1=50, stretching rather than translating it. Both
-    endpoints must move by the same delta."""
-    body = _method_source(APP, "_alignElement")
-    x_branch = body[body.index("if (axis === 'x')"):body.index("} else {")]
-    y_branch = body[body.index("} else {"):]
-    assert "el.x1" in x_branch, \
-        "_alignElement moves x0 but not x1 -- a line's shape changes, not its position"
-    assert "el.y1" in y_branch, \
-        "_alignElement moves y0 but not y1 -- a line's shape changes, not its position"
-
-
-def test_divider_stroke_is_centered_in_led_pixels():
-    """A 0.5 canvas-pixel offset (correct only at SCALE=1) was applied after
-    scaling instead of before it, so at SCALE>1 the stroke bled into the
-    preceding LED row/column instead of straddling its own."""
-    body = _function_source(CANVAS, "_drawElement")
-    divider_branch = body[body.index("case 'divider'"):]
-    divider_branch = divider_branch[:divider_branch.index("case 'pips'")]
-    assert "ay * s + 0.5" not in divider_branch, \
-        "divider still offsets by 0.5 canvas pixels after scaling"
-    assert "ax * s + 0.5" not in divider_branch, \
-        "divider still offsets by 0.5 canvas pixels after scaling"
-    assert "(ay + 0.5) * s" in divider_branch and "(ax + 0.5) * s" in divider_branch, \
-        "divider stroke is not centered within its LED pixel"
-
-
-def test_gauge_radii_are_clamped_to_zero():
-    """An imported design can carry a small gauge with a wide lineWidth --
-    width=1, height=1, lineWidth=3 sends a negative radius into
-    ctx.ellipse(), which throws IndexSizeError and aborts render() for every
-    element still to be drawn, not just the gauge."""
-    body = _function_source(CANVAS, "_drawElement")
-    gauge_branch = body[body.index("case 'gauge'"):]
-    assert re.search(r"Math\.max\(0,\s*rx\s*-\s*lwPx\s*/\s*2\)", gauge_branch), \
-        "gauge x-radius is not clamped to zero"
-    assert re.search(r"Math\.max\(0,\s*ry\s*-\s*lwPx\s*/\s*2\)", gauge_branch), \
-        "gauge y-radius is not clamped to zero"
-    assert "rx - lwPx / 2" not in re.sub(r"Math\.max\(0,\s*rx\s*-\s*lwPx\s*/\s*2\)", "", gauge_branch), \
-        "an unclamped gauge radius is still passed to ctx.ellipse()"
-
-
-#: ELEMENT_DEFAULTS in composer-canvas.js gives exactly these types a
-#: `binding` object; verified against that file rather than assumed.
-BOUND_TYPES = ["dynamic_text", "progress_bar", "countdown", "pips", "sparkline", "gauge"]
-
-
-def test_bound_types_constant_lists_every_bound_element_type():
-    """ELEMENT_DEFAULTS in composer-canvas.js gives dynamic_text, progress_bar,
-    countdown, pips, sparkline and gauge a `binding` object. If a type is added
-    to (or removed from) that list without updating APP's BOUND_TYPES, the
-    checks below drift out of sync silently -- this pins the two together."""
-    src = APP.read_text()
-    match = re.search(r"const BOUND_TYPES = \[([^\]]*)\];", src)
-    assert match, "BOUND_TYPES constant not found in composer-app.js"
-    declared = {t.strip().strip("'\"") for t in match.group(1).split(",") if t.strip()}
-    assert declared == set(BOUND_TYPES), \
-        f"BOUND_TYPES {declared} does not match the bound element types {set(BOUND_TYPES)}"
-
-
-@pytest.mark.parametrize("method", ["_isBound", "removeConfigVar", "_validateBeforeExport"])
-def test_binding_checks_cover_every_bound_element_type(method):
-    """Only dynamic_text and progress_bar were checked, so a countdown, pips,
-    sparkline or gauge element with an empty binding passed export validation
-    silently, and deleting a config var still used by one of them gave no
-    warning -- the plugin would read a now-missing key at runtime with no
-    indication why."""
-    body = _method_source(APP, method)
-    assert "BOUND_TYPES.includes(e.type)" in body, \
-        f"{method} does not check every bound element type via BOUND_TYPES"
-    assert "e.type === 'dynamic_text'" not in body, \
-        f"{method} still hardcodes only dynamic_text instead of BOUND_TYPES"

test/test_composer_path_containment.py

@@ -1,225 +0,0 @@
-"""A composer plugin id must never resolve outside the plugins directory.
-
-CodeQL reported sixteen high-severity py/path-injection alerts against
-web_interface/blueprints/composer.py: a request-supplied plugin_id reaching
-Path(plugins_dir) / plugin_id, which is then created, written to, deleted
-(shutil.rmtree) and read back.
-
-The id was already validated by an anchored regex, so every traversal payload
-was in fact rejected. What was missing was the guarantee living *with* the path
-building rather than in a regex several hundred lines away -- loosen that regex
-later and the traversal opens silently, with nothing at the filesystem boundary
-to catch it. _plugin_dir() closes that, and is the form static analysis can see.
-"""
-import sys
-from pathlib import Path
-from unittest.mock import MagicMock
-
-import pytest
-
-sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
-
-from web_interface.blueprints import composer as C  # noqa: E402
-
-#: Anything that has ever been used to climb out of a directory.
-TRAVERSAL = [
-    "../../etc/passwd", "..", ".", "a/../../etc", "good/../../..",
-    "/etc/passwd", "//etc/passwd", "a\\..\\..", "a%2f..%2f..",
-    "....//....//etc", "a/./../../etc", "~", "~root",
-    "plugin/../../../../../../etc/shadow",
-]
-
-#: Rejected for shape, not traversal -- but rejected all the same.
-MALFORMED = ["", "A-upper", "1-leading-digit", "-leading-dash", "has_underscore",
-             "has space", "has.dot", "a" * 64, "plugin\n", "plugin\n../../etc",
-             "\n", "plug\x00in"]
-
-
-@pytest.fixture
-def plugins_dir(tmp_path, monkeypatch):
-    base = tmp_path / "plugin-repos"
-    base.mkdir()
-    monkeypatch.setattr(C.composer_bp, "plugins_dir", str(base), raising=False)
-    return base
-
-
-@pytest.mark.parametrize("payload", TRAVERSAL)
-def test_traversal_payloads_are_refused(plugins_dir, payload):
-    assert C._plugin_dir(payload) is None
-
-
-@pytest.mark.parametrize("payload", MALFORMED)
-def test_malformed_ids_are_refused(plugins_dir, payload):
-    assert C._plugin_dir(payload) is None
-
-
-@pytest.mark.parametrize("payload", ["a", "my-plugin", "x9", "a" * 63])
-def test_valid_ids_resolve_inside_the_base(plugins_dir, payload):
-    resolved = C._plugin_dir(payload)
-    assert resolved is not None, f"{payload!r} was rejected but is valid"
-    assert resolved.parent == plugins_dir.resolve(), (
-        f"{payload!r} resolved to {resolved}, outside {plugins_dir}")
-
-
-def test_no_payload_can_escape_even_if_the_regex_is_loosened(plugins_dir, monkeypatch):
-    """The containment check must stand on its own.
-
-    This is the whole point of resolving at the filesystem boundary: if the id
-    pattern is ever relaxed, traversal must still be impossible. Replace the
-    regex with one that permits slashes and dots, then re-run the payloads.
-    """
-    import re
-    monkeypatch.setattr(C, "_PLUGIN_ID_RE", re.compile(r"\A[\w./\\~-]+\Z"))
-    import os
-    escaped = []
-    base = os.path.realpath(str(plugins_dir))
-    for payload in TRAVERSAL:
-        resolved = C._plugin_dir(payload)
-        if resolved is None:
-            continue
-        real = os.path.realpath(str(resolved))
-        if real != base and os.path.commonpath([base, real]) != base:
-            escaped.append((payload, real))
-    assert not escaped, f"these escaped the base with a loosened regex: {escaped}"
-
-
-def test_a_sibling_directory_with_a_shared_prefix_is_not_inside(tmp_path, monkeypatch):
-    """commonpath, not startswith.
-
-    "/x/plugins-evil" starts with "/x/plugins" but is a different directory, so
-    a prefix test would accept it.
-    """
-    base = tmp_path / "plugins"
-    base.mkdir()
-    (tmp_path / "plugins-evil").mkdir()
-    monkeypatch.setattr(C.composer_bp, "plugins_dir", str(base), raising=False)
-    import re
-    # Neutralise the two layers in front so this exercises the containment
-    # check itself; otherwise secure_filename rejects the payload first and a
-    # startswith regression would go unnoticed here.
-    monkeypatch.setattr(C, "_PLUGIN_ID_RE", re.compile(r"\A[\w./\\~-]+\Z"))
-    monkeypatch.setattr(C, "secure_filename", lambda v: v)
-    assert C._plugin_dir("../plugins-evil") is None
-
-
-def test_containment_still_holds_if_the_sanitiser_is_defeated(plugins_dir, monkeypatch):
-    """Each layer is tested on its own, not just the stack.
-
-    secure_filename's equality guard rejects every traversal payload before the
-    containment check sees it, so removing containment does not fail the other
-    tests -- which would make it look load-bearing when it is not. Neutralise
-    the regex *and* the sanitiser, and the realpath/commonpath check must still
-    refuse everything on its own.
-    """
-    import re
-    monkeypatch.setattr(C, "_PLUGIN_ID_RE", re.compile(r"\A[\w./\\~-]+\Z"))
-    monkeypatch.setattr(C, "secure_filename", lambda v: v)
-    import os
-    base = os.path.realpath(str(plugins_dir))
-    escaped = []
-    for payload in TRAVERSAL:
-        resolved = C._plugin_dir(payload)
-        if resolved is None:
-            continue
-        real = os.path.realpath(str(resolved))
-        # Inside the base is fine -- "...." and "~" are ordinary directory
-        # names on Linux, so they are not escapes. What must never happen is
-        # landing outside the base, or on the base itself: install() rmtrees
-        # its target, so the plugins root resolving to a "plugin" would wipe
-        # every installed plugin.
-        if real == base or os.path.commonpath([base, real]) != base:
-            escaped.append((payload, real))
-    assert not escaped, f"containment alone let these through: {escaped}"
-
-
-def test_secure_filename_never_rewrites_an_accepted_id(plugins_dir):
-    """The sanitiser must be a no-op on everything the regex accepts.
-
-    If secure_filename ever altered an accepted id, _plugin_dir would resolve
-    to a *different* plugin's directory than the caller asked for -- a silent
-    redirect, which is worse than a refusal. The guard turns that into a
-    refusal; this proves the guard never has to fire in practice.
-    """
-    import random
-    from werkzeug.utils import secure_filename
-    random.seed(1)
-    alphabet = "abcdefghijklmnopqrstuvwxyz0123456789-"
-    altered = []
-    for _ in range(2000):
-        n = random.randint(1, 63)
-        cand = random.choice("abcdefghijklmnopqrstuvwxyz") + "".join(
-            random.choice(alphabet) for _ in range(n - 1))
-        if C._PLUGIN_ID_RE.match(cand) and secure_filename(cand) != cand:
-            altered.append((cand, secure_filename(cand)))
-    assert not altered, f"secure_filename rewrote accepted ids: {altered[:5]}"
-
-
-def test_a_trailing_newline_is_not_a_valid_id():
-    r"""Python's `$` also matches before a trailing newline, so the original
-    `^...$` accepted "myplugin\n" and would have created a directory whose
-    name ends in one. \Z does not."""
-    assert C._PLUGIN_ID_RE.match("myplugin") is not None
-    assert C._PLUGIN_ID_RE.match("myplugin\n") is None
-
-
-# --- font serving -----------------------------------------------------------
-
-FONT_TRAVERSAL = [
-    "../../../etc/passwd", "../config/config.json", "..%2f..%2fetc%2fpasswd",
-    "PressStart2P-Regular.ttf/../../../etc/passwd", "/etc/passwd", "",
-    "PressStart2P-Regular.TTF",          # case differs -> not the allowlisted name
-    "PressStart2P-Regular.ttf ",         # trailing space
-]
-
-
-def test_serve_font_refuses_a_file_that_exists_but_is_not_allowlisted(monkeypatch, tmp_path):
-    """The allowlist must be what refuses it, not a missing file.
-
-    Asserting 404 on traversal payloads proves nothing here: Flask's router
-    will not match a path segment containing '/', and everything else 404s
-    simply because no such file exists. Put a real, readable file next to the
-    fonts and confirm it is still refused -- that is the allowlist working.
-    """
-    fonts = tmp_path / "assets" / "fonts"
-    fonts.mkdir(parents=True)
-    (fonts / "id_rsa.ttf").write_bytes(b"PRIVATE KEY")
-    monkeypatch.setattr(C.composer_bp, "project_root", str(tmp_path), raising=False)
-    app = __import__("flask").Flask(__name__)
-    app.register_blueprint(C.composer_bp)
-    with app.test_client() as client:
-        resp = client.get("/api/fonts/id_rsa.ttf")
-    assert resp.status_code == 404, (
-        "a readable non-allowlisted file was served; the allowlist is not gating")
-    assert b"PRIVATE KEY" not in resp.data
-
-
-@pytest.mark.parametrize("payload", FONT_TRAVERSAL)
-def test_serve_font_refuses_anything_not_allowlisted(payload, monkeypatch, tmp_path):
-    """The name reaching the filesystem must come from the allowlist constant.
-
-    _ALLOWED_FONTS gates this endpoint, so nothing here was ever exploitable.
-    Building the path from the matched constant rather than the request value
-    is what makes that provable -- and it is why CodeQL reported two
-    high-severity py/path-injection alerts on an endpoint that was already
-    safe.
-    """
-    monkeypatch.setattr(C.composer_bp, "project_root", str(tmp_path), raising=False)
-    app = C.composer_bp.name and __import__("flask").Flask(__name__)
-    app.register_blueprint(C.composer_bp)
-    with app.test_client() as client:
-        resp = client.get(f"/api/fonts/{payload}")
-    assert resp.status_code in (404, 405, 308), (
-        f"{payload!r} was not refused (status {resp.status_code})")
-
-
-def test_serve_font_still_serves_each_allowlisted_font(monkeypatch, tmp_path):
-    fonts = tmp_path / "assets" / "fonts"
-    fonts.mkdir(parents=True)
-    monkeypatch.setattr(C.composer_bp, "project_root", str(tmp_path), raising=False)
-    app = __import__("flask").Flask(__name__)
-    app.register_blueprint(C.composer_bp)
-    for name in C._ALLOWED_FONTS:
-        (fonts / name).write_bytes(b"\x00\x01ttf")
-        with app.test_client() as client:
-            resp = client.get(f"/api/fonts/{name}")
-        assert resp.status_code == 200, f"{name} should be served, got {resp.status_code}"

test/test_discovery_path_contract.py

@@ -116,6 +116,77 @@ class TestFallbackDivergence:
             plugin_dir / "config_schema.json"
 
 
+class TestRegistryIdVersusDirectoryName:
+    """install_plugin() renames a plugin's directory to the MANIFEST id when it
+    differs from the REGISTRY id, so `stocks` in the registry lands in
+    `ledmatrix-stocks/`. Every path lookup is by directory name, so
+    update_plugin("stocks") used to find nothing and report the plugin as not
+    installed -- silently. Four installed plugins hit this in practice
+    (leaderboard, music, stocks, weather): the user clicks update, nothing
+    happens, no error, and they stay on a stale version indefinitely.
+    """
+
+    def test_resolves_a_plugin_whose_directory_name_differs_from_its_id(self, tmp_path):
+        configured = tmp_path / "plugin-repos"
+        configured.mkdir()
+        plugin_dir = _write_plugin(configured, "stocks", dir_name="ledmatrix-stocks")
+
+        store = PluginStoreManager(plugins_dir=str(configured))
+        assert store._find_plugin_path("stocks") == plugin_dir
+
+    def test_direct_directory_hit_still_wins(self, tmp_path):
+        """The manifest scan is a last resort. A directory named for the id
+        must still be preferred, so the two documented lookups above keep
+        their exact meaning."""
+        configured = tmp_path / "plugin-repos"
+        configured.mkdir()
+        direct = _write_plugin(configured, "demo", dir_name="demo")
+        # A second directory whose manifest claims the same id.
+        _write_plugin(configured, "demo", dir_name="zz-other-demo")
+
+        store = PluginStoreManager(plugins_dir=str(configured))
+        assert store._find_plugin_path("demo") == direct
+
+    def test_unknown_id_is_still_not_found(self, tmp_path):
+        configured = tmp_path / "plugin-repos"
+        configured.mkdir()
+        _write_plugin(configured, "stocks", dir_name="ledmatrix-stocks")
+
+        store = PluginStoreManager(plugins_dir=str(configured))
+        assert store._find_plugin_path("no-such-plugin") is None
+
+    def test_half_finished_installs_are_not_resurrected(self, tmp_path):
+        """A directory renamed aside during install/rollback carries a valid
+        manifest. Matching one would report a ghost plugin as installed."""
+        configured = tmp_path / "plugin-repos"
+        configured.mkdir()
+        _write_plugin(configured, "ghost",
+                      dir_name="ghost.standalone-backup-1234")
+
+        store = PluginStoreManager(plugins_dir=str(configured))
+        assert store._find_plugin_path("ghost") is None
+
+    def test_unreadable_manifest_does_not_break_the_scan(self, tmp_path):
+        configured = tmp_path / "plugin-repos"
+        configured.mkdir()
+        broken = configured / "broken-plugin"
+        broken.mkdir()
+        (broken / "manifest.json").write_text("{ not json")
+        wanted = _write_plugin(configured, "stocks", dir_name="ledmatrix-stocks")
+
+        store = PluginStoreManager(plugins_dir=str(configured))
+        assert store._find_plugin_path("stocks") == wanted
+
+    def test_sibling_plugins_dir_is_searched_too(self, tmp_path):
+        configured = tmp_path / "plugin-repos"
+        configured.mkdir()
+        legacy = _write_plugin(tmp_path / "plugins", "weather",
+                               dir_name="ledmatrix-weather")
+
+        store = PluginStoreManager(plugins_dir=str(configured))
+        assert store._find_plugin_path("weather") == legacy
+
+
 class TestStandaloneBackupContract:
     def test_discovery_skips_backup_dirs(self, tmp_path):
         plugins_dir = tmp_path / "plugins"

test/test_display_dirty_tracking.py

@@ -47,12 +47,17 @@ class _SwapSpy:
     def __init__(self, matrix):
         self.matrix = matrix
         self.count = 0
+        self.last_frame_hold = None
         self._orig = matrix.SwapOnVSync
 
     def __enter__(self):
-        def counting(canvas):
+        def counting(canvas, *args):
+            # *args carries framerate_fraction, which display_manager passes so
+            # a frame can be held for several refreshes. Signature must match
+            # the real binding or the spy hides a TypeError as a failed push.
             self.count += 1
-            return self._orig(canvas)
+            self.last_frame_hold = args[0] if args else 1
+            return self._orig(canvas, *args)
         self.matrix.SwapOnVSync = counting
         return self
 
@@ -109,6 +114,11 @@ class TestDirtyTracking:
         dm.draw.rectangle([0, 0, 30, 8], fill=(255, 255, 0))
         dm.update_display()   # push + snapshot write (first frame)
         assert os.path.exists(dm._snapshot_path)
+        # Backdate the file so the "was it bumped?" check below cannot be
+        # defeated by filesystem mtime granularity -- on Windows two writes in
+        # the same tick get identical timestamps, which made this test fail
+        # roughly two runs in three regardless of the code under test.
+        os.utime(dm._snapshot_path, (time.time() - 60, time.time() - 60))
         first_mtime = os.path.getmtime(dm._snapshot_path)
 
         # Age the write/touch bookkeeping past TOUCH_INTERVAL so the next
@@ -125,6 +135,62 @@ class TestDirtyTracking:
         assert os.path.getmtime(dm._snapshot_path) > first_mtime
 
 
+class TestScrollLock:
+    """Dirty tracking must not skip the panel push while a scroll is running.
+
+    SwapOnVSync is what paces the render loop, so skipping it also skips the
+    wait for the panel. A duplicate frame therefore returns early -- ~8ms
+    instead of ~10ms on a 100Hz panel -- which advances the strip only 0.8px
+    instead of 1.0px, which makes the NEXT frame more likely to be a duplicate
+    too. That is self-sustaining: measured at ~20% duplicate frames mid-scroll
+    on the odds ticker against essentially zero on a lighter plugin with
+    identical scroll settings. Pushing an identical frame costs one canvas
+    copy; falling out of vsync lock costs smooth motion.
+    """
+
+    def test_identical_frames_still_push_while_scrolling(self, dm):
+        dm.draw.rectangle([0, 0, 12, 12], fill=(0, 0, 255))
+        dm.update_display()
+        dm.set_scrolling_state(True)
+        try:
+            with _SwapSpy(dm.matrix) as spy:
+                dm.update_display()
+                dm.update_display()
+                dm.update_display()
+            assert spy.count == 3, "scrolling must stay locked to the panel"
+        finally:
+            dm.set_scrolling_state(False)
+
+    def test_identical_frames_are_skipped_when_not_scrolling(self, dm):
+        """The optimisation still applies to static content."""
+        dm.set_scrolling_state(False)
+        dm.draw.rectangle([0, 0, 14, 14], fill=(255, 0, 255))
+        dm.update_display()
+        with _SwapSpy(dm.matrix) as spy:
+            dm.update_display()
+            dm.update_display()
+        assert spy.count == 0
+
+    def test_stale_scrolling_state_stops_forcing_pushes(self, dm):
+        """A plugin that stops scrolling without saying so must not pin the
+        panel into always-push forever. is_currently_scrolling() expires on
+        its own inactivity threshold, and the skip has to come back with it."""
+        dm.draw.rectangle([0, 0, 16, 16], fill=(0, 255, 255))
+        dm.update_display()
+        dm.set_scrolling_state(True)
+        try:
+            # Backdate the activity marker past the inactivity threshold.
+            dm._scrolling_state['last_scroll_activity'] = (
+                time.time() - dm._scrolling_state['scroll_inactivity_threshold'] - 1.0)
+            assert dm.is_currently_scrolling() is False
+            with _SwapSpy(dm.matrix) as spy:
+                dm.update_display()
+                dm.update_display()
+            assert spy.count == 0
+        finally:
+            dm.set_scrolling_state(False)
+
+
 class TestKillSwitch:
     def test_dirty_tracking_can_be_disabled(self, dm):
         dm._dirty_tracking_enabled = False
@@ -160,3 +226,89 @@ class TestKillSwitch:
 
 if __name__ == "__main__":
     sys.exit(pytest.main([__file__, "-v"]))
+
+
+class TestFrameHold:
+    """Holding a frame for N refreshes is how a scroll runs slower than one
+    pixel per refresh without fractional pixel positions."""
+
+    def test_hold_reaches_swap_on_vsync(self, dm):
+        dm.set_scrolling_state(True)
+        dm.set_frame_hold(3)
+        try:
+            dm.draw.rectangle([0, 0, 9, 9], fill=(120, 0, 200))
+            with _SwapSpy(dm.matrix) as spy:
+                dm.update_display()
+            assert spy.count == 1
+            assert spy.last_frame_hold == 3
+        finally:
+            dm.set_scrolling_state(False)
+
+    def test_default_is_every_refresh(self, dm):
+        dm.set_scrolling_state(True)
+        try:
+            dm.draw.rectangle([0, 0, 11, 11], fill=(0, 120, 200))
+            with _SwapSpy(dm.matrix) as spy:
+                dm.update_display()
+            assert spy.last_frame_hold == 1
+        finally:
+            dm.set_scrolling_state(False)
+
+    def test_hold_resets_when_scrolling_stops(self, dm):
+        """One plugin's pacing must not leak into whatever is on screen next."""
+        dm.set_scrolling_state(True)
+        dm.set_frame_hold(5)
+        dm.set_scrolling_state(False)
+        dm.set_scrolling_state(True)
+        try:
+            dm.draw.rectangle([0, 0, 13, 13], fill=(200, 120, 0))
+            with _SwapSpy(dm.matrix) as spy:
+                dm.update_display()
+            assert spy.last_frame_hold == 1
+        finally:
+            dm.set_scrolling_state(False)
+
+    @pytest.mark.parametrize("bad,expected", [(0, 1), (-4, 1), (None, 1), ("x", 1)])
+    def test_unusable_holds_are_ignored_or_floored(self, dm, bad, expected):
+        dm.set_frame_hold(bad)
+        assert dm._frame_hold == expected
+
+
+class TestFrameHoldLifetime:
+    """The hold must last exactly as long as the scroll that asked for it.
+
+    Plugins share one display manager. A hold applied at plugin construction is
+    wiped the moment any *other* plugin finishes scrolling, so by the time the
+    first plugin renders it is back to one pixel per refresh -- the speed reads
+    correct in the log and is wrong on the panel.
+    """
+
+    def test_scrolling_state_carries_the_hold(self, dm):
+        dm.set_scrolling_state(True, frame_hold=4)
+        try:
+            dm.draw.rectangle([0, 0, 7, 7], fill=(10, 200, 10))
+            with _SwapSpy(dm.matrix) as spy:
+                dm.update_display()
+            assert spy.last_frame_hold == 4
+        finally:
+            dm.set_scrolling_state(False)
+
+    def test_another_plugin_stopping_does_not_strand_a_hold(self, dm):
+        dm.set_scrolling_state(True, frame_hold=3)
+        dm.set_scrolling_state(False)          # some other plugin finishes
+        dm.set_scrolling_state(True)           # a plugin that wants no hold
+        try:
+            dm.draw.rectangle([0, 0, 6, 6], fill=(200, 10, 10))
+            with _SwapSpy(dm.matrix) as spy:
+                dm.update_display()
+            assert spy.last_frame_hold == 1
+        finally:
+            dm.set_scrolling_state(False)
+
+    def test_default_keeps_previous_behaviour(self, dm):
+        """Callers that never heard of frame holds get one frame per refresh."""
+        dm.set_scrolling_state(True)
+        try:
+            assert dm._frame_hold == 1
+        finally:
+            dm.set_scrolling_state(False)

test/test_display_double_parity.py

@@ -0,0 +1,69 @@
+"""The visual-test double must not drift from the real DisplayManager.
+
+Both directions of drift are silent and both are damaging:
+
+  * the double accepts an argument production does not -- the call passes
+    every harness run and raises TypeError on the panel, which is precisely
+    the failure a safety harness exists to prevent;
+  * the double lacks an argument production has -- every plugin that
+    legitimately uses it fails every render, and the harness blames the
+    plugin.
+
+`set_scrolling_state` has been each of those in turn across two branches, so
+the parity is asserted rather than remembered.
+
+Read with ast rather than imported: src/display_manager.py imports rgbmatrix
+at module scope, which is absent anywhere without the panel library, and this
+check should hold on a laptop and in CI as well as on a Pi.
+"""
+
+import ast
+from pathlib import Path
+
+import pytest
+
+ROOT = Path(__file__).resolve().parent.parent
+REAL = ROOT / "src" / "display_manager.py"
+DOUBLE = ROOT / "src" / "plugin_system" / "testing" / "visual_display_manager.py"
+
+#: Methods a plugin calls on whichever manager it is handed.
+SHARED_METHODS = ["set_scrolling_state", "is_currently_scrolling"]
+
+
+def _signature(path: Path, class_hint: str, method: str):
+    """(name, default-repr) pairs for `method`, or None if it is absent."""
+    tree = ast.parse(path.read_text(encoding="utf-8"))
+    for node in ast.walk(tree):
+        if not isinstance(node, ast.ClassDef) or class_hint not in node.name:
+            continue
+        for item in node.body:
+            if isinstance(item, (ast.FunctionDef, ast.AsyncFunctionDef)) and item.name == method:
+                args = [a.arg for a in item.args.args if a.arg != "self"]
+                pad = [None] * (len(args) - len(item.args.defaults))
+                defaults = pad + [ast.unparse(d) for d in item.args.defaults]
+                return list(zip(args, defaults))
+    return None
+
+
+@pytest.mark.parametrize("method", SHARED_METHODS)
+def test_the_double_matches_production(method):
+    real = _signature(REAL, "DisplayManager", method)
+    double = _signature(DOUBLE, "DisplayManager", method)
+
+    assert real is not None, f"DisplayManager lost {method}"
+    assert double is not None, \
+        f"the test double is missing {method}, so every plugin using it fails to render"
+    assert double == real, (
+        f"{method} has drifted: production takes {real}, the double takes {double}. "
+        "A double that is more permissive hides a production TypeError; one that "
+        "is less permissive fails plugins that are actually correct."
+    )
+
+
+def test_frame_hold_is_accepted_by_both():
+    """The specific argument that has drifted twice."""
+    for path, label in ((REAL, "DisplayManager"), (DOUBLE, "VisualTestDisplayManager")):
+        params = dict(_signature(path, "DisplayManager", "set_scrolling_state") or [])
+        assert "frame_hold" in params, f"{label} does not accept frame_hold"
+        assert params["frame_hold"] == "1", \
+            f"{label} must default frame_hold to 1 so existing callers are unaffected"

test/test_harness_empty_claimed.py

@@ -101,3 +101,61 @@ class TestSkippedResults:
         r = _result(None, returned=None)
         check_empty_claimed([r], strict=True)
         assert r.empty_claimed is None
+
+
+class TestSettleRecordsLaterFailures:
+    """A mode that renders one good frame and then crashes is broken.
+
+    _settle_loop re-renders a mode that came back blank, to give a scroll or an
+    animation time to put something on the panel. Swallowing an exception from
+    those later frames meant the harness reported a passing result for a mode
+    that crashes as soon as it is asked for a second frame -- exactly the kind
+    of defect the harness exists to catch.
+    """
+
+    class Boom:
+        """Renders once, then raises."""
+
+        def __init__(self):
+            self.calls = 0
+
+        def display(self, force_clear=False):
+            self.calls += 1
+            raise RuntimeError("second frame exploded")
+
+    def _settle(self, inst, dm, result):
+        from src.plugin_system.testing import harness
+        harness._settle_loop(inst, "mode", dm, result, None)
+
+    def test_the_exception_is_recorded_on_the_result(self, monkeypatch):
+        from src.plugin_system.testing import harness
+        # Keep the probe short; this test is about the error, not the pacing.
+        monkeypatch.setattr(harness, "EMPTY_RECHECK_FRAMES", 1)
+        monkeypatch.setattr(harness, "EMPTY_RECHECK_STEP", 0)
+
+        result = _result(_blank())
+        assert result.error is None
+        self._settle(self.Boom(), _FakeDM(), result)
+
+        assert result.error is not None, "a crash on a later frame was swallowed"
+        assert "second frame exploded" in result.error
+
+    def test_the_already_captured_frame_is_kept(self, monkeypatch):
+        from src.plugin_system.testing import harness
+        monkeypatch.setattr(harness, "EMPTY_RECHECK_FRAMES", 1)
+        monkeypatch.setattr(harness, "EMPTY_RECHECK_STEP", 0)
+
+        image = _blank()
+        result = _result(image)
+        self._settle(self.Boom(), _FakeDM(), result)
+        assert result.image is image, "the good frame was discarded along with the error"
+
+
+class _FakeDM:
+    """Minimal display-manager double for _settle_loop."""
+
+    def get_image(self):
+        return _blank()
+
+    def check_overflow(self):
+        return None

test/test_on_demand_mailbox.py

@@ -0,0 +1,106 @@
+"""The on-demand request mailbox: how often it is read, and how it is consumed.
+
+The mailbox is a cache key the web process writes and the display process
+reads. Two properties matter and neither is obvious from the call site:
+
+  * it is polled after every rendered frame, so an uncached read here is a
+    disk read at frame rate;
+  * consuming it must not throw away a request that arrived while the previous
+    one was being processed.
+"""
+
+from unittest.mock import MagicMock
+
+import pytest
+
+
+class TestPollingIsBounded:
+    """_poll_on_demand_requests runs ~125x/second on a scrolling mode.
+
+    The read is deliberately uncached (memory_ttl=0) because a cached one
+    pinned the first request for an hour. That makes the call a real disk read,
+    so it needs a floor -- without one it was ~125 reads per second to find
+    nothing at all.
+    """
+
+    def test_first_call_always_reads(self, test_display_controller):
+        c = test_display_controller
+        c.cache_manager.get = MagicMock(return_value=None)
+        c._poll_on_demand_requests()
+        assert c.cache_manager.get.call_count == 1
+
+    def test_immediate_second_call_does_not_read(self, test_display_controller):
+        c = test_display_controller
+        c.cache_manager.get = MagicMock(return_value=None)
+        c._poll_on_demand_requests()
+        for _ in range(50):
+            c._poll_on_demand_requests()
+        assert c.cache_manager.get.call_count == 1, "polling was not bounded"
+
+    def test_reads_again_once_the_interval_has_passed(self, test_display_controller, monkeypatch):
+        c = test_display_controller
+        c.cache_manager.get = MagicMock(return_value=None)
+        clock = {"t": 1000.0}
+        monkeypatch.setattr("src.display_controller.time.monotonic", lambda: clock["t"])
+
+        c._poll_on_demand_requests()
+        clock["t"] += c.ON_DEMAND_POLL_INTERVAL / 2
+        c._poll_on_demand_requests()
+        assert c.cache_manager.get.call_count == 1, "read before the interval elapsed"
+
+        clock["t"] += c.ON_DEMAND_POLL_INTERVAL
+        c._poll_on_demand_requests()
+        assert c.cache_manager.get.call_count == 2
+
+    def test_the_interval_is_short_enough_to_feel_instant(self, test_display_controller):
+        # A person clicking in the web UI must not notice the floor.
+        assert test_display_controller.ON_DEMAND_POLL_INTERVAL <= 0.5
+
+
+class TestMailboxIsConsumedByIdentity:
+    """Deleting whatever is in the mailbox loses a request that raced in."""
+
+    def _arrange(self, controller, first, later):
+        """Mailbox returns `first`, then `later` on the pre-delete re-read."""
+        controller.on_demand_active = False
+        controller.on_demand_request_id = None
+        controller._last_on_demand_poll = None
+        reads = iter([first, later])
+
+        def fake_get(key, *a, **kw):
+            if key == 'display_on_demand_request':
+                return next(reads, later)
+            return None  # processed-id lookup
+
+        controller.cache_manager.get = MagicMock(side_effect=fake_get)
+        controller.cache_manager.set = MagicMock()
+        controller.cache_manager.delete = MagicMock()
+        controller._activate_on_demand = MagicMock()
+
+    REQ_A = {'request_id': 'A', 'action': 'start', 'plugin_id': 'p', 'mode': 'm'}
+    REQ_B = {'request_id': 'B', 'action': 'start', 'plugin_id': 'p', 'mode': 'm'}
+
+    def test_own_request_is_deleted(self, test_display_controller):
+        c = test_display_controller
+        self._arrange(c, self.REQ_A, self.REQ_A)
+        c._poll_on_demand_requests()
+        c.cache_manager.delete.assert_called_once_with('display_on_demand_request')
+
+    def test_a_newer_request_is_left_for_the_next_poll(self, test_display_controller):
+        c = test_display_controller
+        self._arrange(c, self.REQ_A, self.REQ_B)
+        c._poll_on_demand_requests()
+        assert c.cache_manager.delete.call_count == 0, \
+            "request B was deleted without ever being processed"
+
+    def test_an_already_empty_mailbox_is_still_cleared(self, test_display_controller):
+        c = test_display_controller
+        self._arrange(c, self.REQ_A, None)
+        c._poll_on_demand_requests()
+        c.cache_manager.delete.assert_called_once_with('display_on_demand_request')
+
+    def test_the_request_is_still_processed(self, test_display_controller):
+        c = test_display_controller
+        self._arrange(c, self.REQ_A, self.REQ_B)
+        c._poll_on_demand_requests()
+        c._activate_on_demand.assert_called_once()

test/test_scroll_config.py

@@ -0,0 +1,467 @@
+"""Tests for the shared scroll configuration resolver."""
+
+import logging
+import sys
+from pathlib import Path
+
+import pytest
+
+sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
+
+from src.common.scroll_config import (  # noqa: E402
+    DEFAULT_PIXELS_PER_SECOND,
+    MAX_PIXELS_PER_FRAME,
+    crisp_ladder,
+    solve_crisp,
+    MAX_PIXELS_PER_SECOND,
+    MIN_PIXELS_PER_SECOND,
+    ScrollSettings,
+    configure,
+    refresh_hz_from_config,
+    resolve,
+)
+
+
+class FakeHelper:
+    """Records what configure() applied."""
+
+    def __init__(self, with_optional=True):
+        self.speed = None
+        self.frame_based = None
+        self.target_fps = None
+        if not with_optional:
+            del FakeHelper.set_frame_based_scrolling
+            del FakeHelper.set_target_fps
+
+    def set_scroll_speed(self, speed):
+        self.speed = speed
+
+    def set_frame_based_scrolling(self, enabled):
+        self.frame_based = enabled
+
+    def set_target_fps(self, fps):
+        self.target_fps = fps
+
+
+class FakeDisplayManager:
+    """Records the frame hold configure() applies."""
+
+    def __init__(self):
+        self.hold = None
+
+    def set_frame_hold(self, refreshes):
+        self.hold = refreshes
+
+
+class MinimalHelper:
+    """An older helper exposing only set_scroll_speed."""
+
+    def __init__(self):
+        self.speed = None
+
+    def set_scroll_speed(self, speed):
+        self.speed = speed
+
+
+class TestPrecedence:
+    def test_display_options_pair_wins(self):
+        s = resolve({"display_options": {"scroll_speed": 1.0, "scroll_delay": 0.01}})
+        assert s.pixels_per_second == 100.0
+        assert s.source == "display_options.scroll_speed/delay"
+
+    def test_display_block_used_when_options_absent(self):
+        s = resolve({"display": {"scroll_speed": 2.0, "scroll_delay": 0.01}})
+        assert s.pixels_per_second == 200.0
+        assert s.source == "display.scroll_speed/delay"
+
+    def test_root_pair_used_when_both_blocks_absent(self):
+        s = resolve({"scroll_speed": 1.0, "scroll_delay": 0.02})
+        assert s.pixels_per_second == 50.0
+
+    def test_pixels_per_second_used_when_no_pair_given(self):
+        s = resolve({"display_options": {"scroll_pixels_per_second": 120.0}})
+        assert s.pixels_per_second == 120.0
+        assert s.source == "display_options.scroll_pixels_per_second"
+
+    def test_global_display_is_the_last_resort_before_default(self):
+        s = resolve({}, {"display": {"scroll_speed": 1.0, "scroll_delay": 0.005}})
+        assert s.pixels_per_second == 200.0
+
+    def test_default_when_nothing_configured(self):
+        s = resolve({}, {})
+        assert s.pixels_per_second == DEFAULT_PIXELS_PER_SECOND
+        assert s.source == "default"
+
+
+class TestDeprecatedKeyCannotOverrideExplicitPair:
+    """Regression for ChuckBuilds/ledmatrix-plugins#408.
+
+    odds-ticker ranked scroll_pixels_per_second above the documented
+    scroll_speed/scroll_delay pair. Because that key carries a schema default,
+    the documented settings became unreachable for every user and the ticker
+    silently ran at the default speed. The pair must win.
+    """
+
+    def test_pair_beats_pixels_per_second_in_the_same_block(self):
+        s = resolve(
+            {
+                "display_options": {
+                    "scroll_speed": 1.0,
+                    "scroll_delay": 0.01,
+                    "scroll_pixels_per_second": 50.0,  # schema default
+                }
+            }
+        )
+        assert s.pixels_per_second == 100.0
+        assert "scroll_speed/delay" in s.source
+
+    def test_pair_beats_pixels_per_second_in_an_outer_block(self):
+        s = resolve(
+            {
+                "display_options": {"scroll_speed": 1.0, "scroll_delay": 0.01},
+                "scroll_pixels_per_second": 50.0,
+            }
+        )
+        assert s.pixels_per_second == 100.0
+
+
+class TestMalformedValues:
+    @pytest.mark.parametrize("bad", [None, "fast", "", {}, [], float("nan")])
+    def test_unusable_speed_falls_through(self, bad):
+        s = resolve({"display_options": {"scroll_speed": bad, "scroll_delay": 0.01}})
+        assert s.pixels_per_second == DEFAULT_PIXELS_PER_SECOND
+
+    @pytest.mark.parametrize("bad", [0, -5, 0.0])
+    def test_non_positive_values_fall_through(self, bad):
+        s = resolve({"display_options": {"scroll_pixels_per_second": bad}})
+        assert s.pixels_per_second == DEFAULT_PIXELS_PER_SECOND
+
+    def test_booleans_are_not_treated_as_numbers(self):
+        s = resolve({"display_options": {"scroll_pixels_per_second": True}})
+        assert s.pixels_per_second == DEFAULT_PIXELS_PER_SECOND
+
+    def test_zero_delay_does_not_divide_by_zero(self):
+        s = resolve({"display_options": {"scroll_speed": 1.0, "scroll_delay": 0}})
+        assert s.pixels_per_second == DEFAULT_PIXELS_PER_SECOND
+
+    def test_non_dict_blocks_are_ignored(self):
+        s = resolve({"display_options": "nonsense", "display": 5})
+        assert s.pixels_per_second == DEFAULT_PIXELS_PER_SECOND
+
+
+class TestClamping:
+    def test_absurdly_fast_is_clamped(self):
+        s = resolve({"display_options": {"scroll_pixels_per_second": 100000.0}})
+        assert s.pixels_per_second == MAX_PIXELS_PER_SECOND
+        assert s.warning and "clamped" in s.warning
+
+    def test_absurdly_slow_is_clamped(self):
+        s = resolve({"display_options": {"scroll_pixels_per_second": 0.01}})
+        assert s.pixels_per_second == MIN_PIXELS_PER_SECOND
+
+
+class TestWholePixelWarning:
+    """The display rule: whole pixels per refresh, or it judders."""
+
+    def test_no_warning_when_speed_divides_evenly(self):
+        s = resolve({"display_options": {"scroll_pixels_per_second": 100.0}}, refresh_hz=100)
+        assert s.warning is None
+        assert s.pixels_per_frame == pytest.approx(1.0)
+
+    def test_no_warning_at_an_integer_multiple(self):
+        s = resolve({"display_options": {"scroll_pixels_per_second": 200.0}}, refresh_hz=100)
+        assert s.warning is None
+
+    def test_warns_on_a_half_pixel_per_frame(self):
+        s = resolve({"display_options": {"scroll_pixels_per_second": 50.0}}, refresh_hz=100)
+        assert s.warning is not None
+        assert "judder" in s.warning
+        assert "100 px/s" in s.warning
+
+    def test_warns_on_a_fractional_multiple(self):
+        s = resolve({"display_options": {"scroll_pixels_per_second": 130.0}}, refresh_hz=100)
+        assert s.warning is not None
+
+    def test_respects_a_non_default_refresh_rate(self):
+        s = resolve({"display_options": {"scroll_pixels_per_second": 150.0}}, refresh_hz=150)
+        assert s.warning is None
+        assert s.pixels_per_frame == pytest.approx(1.0)
+
+
+class TestConfigure:
+    def test_applies_time_based_mode_and_speed(self):
+        helper = FakeHelper()
+        s = configure(helper, {"display_options": {"scroll_speed": 1.0, "scroll_delay": 0.01}})
+        assert helper.speed == 100.0
+        assert helper.frame_based is False, "must not use the wall-clock step gate"
+        assert helper.target_fps == 100.0
+        assert s.pixels_per_second == 100.0
+
+    def test_works_against_a_helper_without_optional_methods(self):
+        helper = MinimalHelper()
+        configure(helper, {"display_options": {"scroll_pixels_per_second": 100.0}})
+        assert helper.speed == 100.0
+
+    def test_snapping_removes_the_judder_warning(self, caplog):
+        """50px/s cannot be shown in whole pixels at 100Hz *per refresh*, but it
+        can as 1px every 2nd refresh -- so once snapped there is nothing to warn
+        about. resolve() alone still warns; configure() resolves it."""
+        assert "judder" in resolve(
+            {"display_options": {"scroll_pixels_per_second": 50.0}},
+            refresh_hz=100).warning
+        helper, dm = FakeHelper(), FakeDisplayManager()
+        with caplog.at_level(logging.WARNING):
+            settings = configure(
+                helper, {"display_options": {"scroll_pixels_per_second": 50.0}},
+                display_manager=dm)
+        assert settings.warning is None
+        assert not [r for r in caplog.records if "judder" in r.getMessage()]
+
+    def test_reports_the_hold_without_applying_it(self):
+        """The hold belongs to a scroll, not a plugin's lifetime -- one left set
+        at construction is wiped as soon as any other plugin stops scrolling.
+        configure() reports it; the caller passes it to set_scrolling_state."""
+        dm = FakeDisplayManager()
+        s = configure(FakeHelper(), {"display_options": {"scroll_pixels_per_second": 25.0}},
+                      display_manager=dm)
+        assert s.frame_hold == 4, "25px/s at 100Hz is 1px every 4th refresh"
+        assert dm.hold is None, "must not apply the hold behind the caller's back"
+
+    def test_full_speed_needs_no_hold(self):
+        s = configure(FakeHelper(), {"display_options": {"scroll_pixels_per_second": 100.0}},
+                      display_manager=FakeDisplayManager())
+        assert s.frame_hold == 1
+
+    def test_frame_hold_is_one_when_snapping_is_off(self):
+        s = configure(FakeHelper(), {"display_options": {"scroll_pixels_per_second": 50.0}},
+                      snap_to_crisp=False)
+        assert s.frame_hold == 1
+
+    def test_snaps_to_the_nearest_crisp_speed_and_reports_both(self):
+        s = configure(FakeHelper(), {"display_options": {"scroll_pixels_per_second": 45.0}},
+                      display_manager=FakeDisplayManager())
+        assert s.requested_pixels_per_second == 45.0
+        assert s.pixels_per_second == 50.0
+        assert s.crisp is not None and s.crisp.pixels_per_frame == 1
+
+    def test_snapping_can_be_turned_off(self):
+        s = configure(FakeHelper(), {"display_options": {"scroll_pixels_per_second": 45.0}},
+                      snap_to_crisp=False)
+        assert s.pixels_per_second == 45.0
+        assert s.crisp is None
+
+    def test_helper_target_fps_matches_the_presentation_rate(self):
+        """At a hold of 4 the panel still refreshes at 100Hz, but frames are
+        presented at 25/s -- that is the rate the helper should pace to."""
+        helper = FakeHelper()
+        configure(helper, {"display_options": {"scroll_pixels_per_second": 25.0}},
+                  display_manager=FakeDisplayManager())
+        assert helper.target_fps == pytest.approx(25.0)
+
+    def test_returns_settings_describing_the_source(self):
+        s = configure(FakeHelper(), {"display_options": {"scroll_speed": 2.0, "scroll_delay": 0.01}})
+        assert isinstance(s, ScrollSettings)
+        assert "200.0 px/s" in s.describe()
+
+
+class TestRefreshFromConfig:
+    def test_reads_the_hardware_limit(self):
+        assert refresh_hz_from_config(
+            {"display": {"hardware": {"limit_refresh_rate_hz": 150}}}
+        ) == 150.0
+
+    @pytest.mark.parametrize("cfg", [None, {}, {"display": {}}, {"display": {"hardware": {}}},
+                                     "nonsense", {"display": {"hardware": {"limit_refresh_rate_hz": None}}}])
+    def test_falls_back_to_the_default(self, cfg):
+        assert refresh_hz_from_config(cfg) == 100.0
+
+    @pytest.mark.parametrize("cfg", [
+        {"display": "nonsense"},
+        {"display": ["nonsense"]},
+        {"display": 60},
+        {"display": {"hardware": "nonsense"}},
+        {"display": {"hardware": ["nonsense"]}},
+        {"display": {"hardware": 60}},
+    ])
+    def test_malformed_nesting_falls_back_rather_than_raising(self, cfg):
+        # Truthy-but-not-a-mapping at either level used to reach .get() on a
+        # str/list and raise AttributeError out of a function whose whole
+        # contract is "a refresh rate, or the default".
+        assert refresh_hz_from_config(cfg) == 100.0
+
+
+class TestCrispLadder:
+    """Whole-pixel speeds available on a given panel."""
+
+    def test_every_entry_is_exactly_reachable(self):
+        for c in crisp_ladder(100):
+            assert c.pixels_per_second == pytest.approx(
+                c.refresh_hz / c.frame_hold * c.pixels_per_frame)
+
+    def test_sorted_slowest_first(self):
+        speeds = [c.pixels_per_second for c in crisp_ladder(100)]
+        assert speeds == sorted(speeds)
+
+    def test_no_duplicate_speeds(self):
+        speeds = [round(c.pixels_per_second, 3) for c in crisp_ladder(100)]
+        assert len(speeds) == len(set(speeds))
+
+    def test_duplicates_resolve_to_the_smaller_step(self):
+        """100px/s is 1px every refresh or 2px every 2nd; prefer the former."""
+        entry = next(c for c in crisp_ladder(100)
+                     if c.pixels_per_second == pytest.approx(100.0))
+        assert entry.pixels_per_frame == 1
+        assert entry.frame_hold == 1
+
+    def test_ladder_scales_with_the_panel(self):
+        assert any(c.pixels_per_second == pytest.approx(60.0)
+                   for c in crisp_ladder(60))
+        assert any(c.pixels_per_second == pytest.approx(30.0)
+                   for c in crisp_ladder(60))
+
+    def test_full_refresh_speed_is_present(self):
+        for hz in (60, 75, 100, 120):
+            assert any(c.pixels_per_second == pytest.approx(float(hz))
+                       for c in crisp_ladder(hz))
+
+
+class TestSolveCrisp:
+    def test_exact_targets_are_matched_exactly(self):
+        for target in (100, 50, 25, 20):
+            assert solve_crisp(target, 100).pixels_per_second == pytest.approx(target)
+
+    def test_prefers_smooth_motion_over_raw_proximity(self):
+        """30 -> 33.3 (1px, 33fps), not 28.6 (2px at 14fps) which is nearer."""
+        got = solve_crisp(30, 100)
+        assert got.pixels_per_second == pytest.approx(33.333, abs=0.01)
+        assert got.pixels_per_frame == 1
+
+    def test_does_not_chase_a_jumpy_exact_match(self):
+        """45 -> 50 (1px, smooth) beats 42.9 (3px at 14fps)."""
+        assert solve_crisp(45, 100).pixels_per_frame == 1
+
+    def test_allows_a_two_pixel_step_when_it_is_clearly_closer(self):
+        """60 -> 66.7 (2px at 33fps) rather than 50 (1px) which is 17% slow."""
+        got = solve_crisp(60, 100)
+        assert got.pixels_per_second == pytest.approx(66.667, abs=0.01)
+        assert got.pixels_per_frame == 2
+
+    def test_result_is_always_on_the_ladder(self):
+        ladder = {round(c.pixels_per_second, 3) for c in crisp_ladder(100)}
+        for target in range(5, 205, 5):
+            assert round(solve_crisp(target, 100).pixels_per_second, 3) in ladder
+
+    def test_adapts_to_a_slower_panel(self):
+        got = solve_crisp(30, 60)
+        assert got.pixels_per_second == pytest.approx(30.0)
+        assert got.pixels_per_frame == 1
+        assert got.frame_hold == 2
+
+    def test_speeds_beyond_the_panel_clamp_to_the_fastest_available(self):
+        got = solve_crisp(10_000, 100)
+        assert got.frame_hold == 1
+        assert got.pixels_per_frame == MAX_PIXELS_PER_FRAME
+
+    def test_steppiness_labels_are_sane(self):
+        assert solve_crisp(100, 100).steppiness == "smooth"
+        assert crisp_ladder(100)[0].steppiness == "stepped"
+
+
+class TestRefreshFromDisplayManager:
+    """A plugin sees only its own config section, so the display manager is the
+    authoritative source for the panel's refresh rate."""
+
+    class DM:
+        def __init__(self, hz):
+            self.refresh_hz = hz
+            self.hold = None
+
+        def set_frame_hold(self, refreshes):
+            self.hold = refreshes
+
+    def test_uses_the_display_manager_rate(self):
+        dm = self.DM(60.0)
+        s = configure(FakeHelper(), {"display_options": {"scroll_pixels_per_second": 30.0}},
+                      display_manager=dm)
+        # 30px/s on a 60Hz panel is 1px every 2nd refresh, exactly.
+        assert s.pixels_per_second == pytest.approx(30.0)
+        assert s.frame_hold == 2
+
+    def test_explicit_refresh_hz_wins_over_the_display_manager(self):
+        dm = self.DM(60.0)
+        s = configure(FakeHelper(), {"display_options": {"scroll_pixels_per_second": 25.0}},
+                      display_manager=dm, refresh_hz=100)
+        assert s.frame_hold == 4, "25px/s at 100Hz is 1px every 4th refresh"
+
+    def test_missing_attribute_falls_back_to_the_default(self):
+        class Bare:
+            def set_frame_hold(self, refreshes):
+                self.hold = refreshes
+
+        bare = Bare()
+        s = configure(FakeHelper(), {"display_options": {"scroll_pixels_per_second": 50.0}},
+                      display_manager=bare)
+        assert s.frame_hold == 2, "assumed 100Hz"
+
+    def test_reported_settings_describe_the_display_manager_rate(self):
+        """Without snapping, nothing downstream corrects a wrong refresh rate.
+
+        The rate used to be read *after* resolve() had already filled in
+        target_fps, pixels_per_frame and the judder warning from the 100Hz
+        default -- so on a 60Hz panel every one of those described 100Hz, and
+        set_target_fps() paced the helper to 100 FPS.
+        """
+        dm = self.DM(60.0)
+        helper = FakeHelper()
+        s = configure(helper, {"display_options": {"scroll_pixels_per_second": 30.0}},
+                      display_manager=dm, snap_to_crisp=False)
+
+        assert s.target_fps == pytest.approx(60.0)
+        assert s.pixels_per_frame == pytest.approx(0.5), "30px/s over 60 frames"
+        assert helper.target_fps == pytest.approx(60.0)
+
+    def test_judder_warning_is_computed_at_the_real_refresh_rate(self):
+        dm = self.DM(60.0)
+        # 60px/s is exactly 1px per refresh at 60Hz -- crisp, no warning. At
+        # the 100Hz default it is 0.6px per refresh and would be flagged.
+        s = configure(FakeHelper(), {"display_options": {"scroll_pixels_per_second": 60.0}},
+                      display_manager=dm, snap_to_crisp=False)
+        assert s.warning is None, s.warning
+
+    def test_global_config_supplies_the_rate_without_a_display_manager(self):
+        s = configure(
+            FakeHelper(),
+            {"display_options": {"scroll_pixels_per_second": 30.0}},
+            {"display": {"hardware": {"limit_refresh_rate_hz": 60}}},
+            snap_to_crisp=False,
+        )
+        assert s.target_fps == pytest.approx(60.0)
+
+
+class TestFrameHoldIsReportedNotApplied:
+    """configure() reports the hold; the caller applies it when it scrolls.
+
+    The hold belongs to a scroll, not to a plugin's lifetime -- plugins share
+    one display manager, so one set at construction is reset the moment any
+    other plugin stops scrolling.
+    """
+
+    class RecordingDM:
+        refresh_hz = 100.0
+
+        def __init__(self):
+            self.calls = []
+
+        def set_scrolling_state(self, is_scrolling, frame_hold=1):
+            self.calls.append((is_scrolling, frame_hold))
+
+        def set_frame_hold(self, refreshes):
+            self.calls.append(("set_frame_hold", refreshes))
+
+    def test_configure_does_not_touch_the_display_manager(self):
+        dm = self.RecordingDM()
+        settings = configure(
+            FakeHelper(), {"display_options": {"scroll_pixels_per_second": 25.0}},
+            display_manager=dm)
+        assert dm.calls == [], "configure() must not apply the hold itself"
+        assert settings.frame_hold == 4, "but it must report what to apply"

test/test_scroll_helper.py

@@ -11,7 +11,11 @@ import time
 from unittest.mock import patch
 from PIL import Image
 
-from src.common.scroll_helper import ScrollHelper
+from src.common.scroll_helper import (
+    ScrollHelper,
+    format_frame_stats,
+    frame_stats,
+)
 
 
 DISPLAY_W = 64
@@ -315,3 +319,77 @@ class TestGetScrollInfo:
         helper.scroll_position = 42.0
         info = helper.get_scroll_info()
         assert info["scroll_position"] == 42.0
+
+
+class TestFrameStatsPercentiles:
+    """The stats line is the instrument this whole scroll change is measured
+    with, so its median and p95 have to be the real ones.
+
+    Both are also thresholds: stalls are counted at 1.5x the median and skips
+    at 0.5x, so an off-by-one in the median biases the counts as well as the
+    printed numbers.
+    """
+
+    # 100 samples of 1..100ms. True median 50.5ms (the mean of the two middle
+    # samples, not the upper one at 51ms); nearest-rank p95 is the 95th
+    # sample at 95ms, not the 96th at 96ms.
+    HUNDRED = [i / 1000.0 for i in range(1, 101)]
+
+    def test_even_window_median_averages_both_middle_samples(self):
+        assert frame_stats(self.HUNDRED)["median"] == pytest.approx(0.0505)
+
+    def test_p95_uses_nearest_rank(self):
+        assert frame_stats(self.HUNDRED)["p95"] == pytest.approx(0.095)
+
+    def test_odd_window_median_is_the_middle_sample(self):
+        times = [i / 1000.0 for i in range(1, 102)]  # 101 samples
+        assert frame_stats(times)["median"] == pytest.approx(0.051)
+
+    def test_single_sample_window_does_not_index_out_of_range(self):
+        stats = frame_stats([0.010])
+        assert stats["median"] == pytest.approx(0.010)
+        assert stats["p95"] == pytest.approx(0.010)
+        assert stats["min"] == stats["max"] == pytest.approx(0.010)
+
+    def test_two_sample_window(self):
+        stats = frame_stats([0.010, 0.020])
+        assert stats["median"] == pytest.approx(0.015)
+        assert stats["p95"] == pytest.approx(0.020)
+
+    def test_input_order_does_not_matter(self):
+        assert frame_stats(list(reversed(self.HUNDRED))) == frame_stats(self.HUNDRED)
+
+    def test_caller_window_is_not_mutated(self):
+        times = [0.030, 0.010, 0.020]
+        frame_stats(times)
+        assert times == [0.030, 0.010, 0.020]
+
+    def test_stall_threshold_follows_the_median(self):
+        # Ten 10ms frames and two 30ms stalls: median 10ms, so >15ms is a
+        # stall -- exactly the two.
+        stats = frame_stats([0.010] * 10 + [0.030] * 2)
+        assert stats["stalls"] == 2
+        assert stats["skips"] == 0
+
+    def test_skips_are_frames_that_never_reached_the_panel(self):
+        stats = frame_stats([0.010] * 10 + [0.002] * 3)
+        assert stats["skips"] == 3
+        assert stats["stalls"] == 0
+
+    def test_fps_is_the_reciprocal_of_the_mean(self):
+        assert frame_stats([0.010] * 50)["fps"] == pytest.approx(100.0)
+
+    def test_formatted_line_reports_the_corrected_values(self):
+        line = format_frame_stats(self.HUNDRED)
+        assert "median 50.50ms" in line, line
+        assert "p95 95.00ms" in line, line
+        assert "over 100 frames" in line, line
+
+    def test_log_frame_rate_emits_the_line_and_clears_the_window(self, helper):
+        helper._window = [0.010] * 20
+        helper.last_fps_log_time = 0.0  # force the 5s boundary
+        with patch.object(helper.logger, "info") as info:
+            helper.log_frame_rate()
+        assert info.called
+        assert "Scroll frame stats" in info.call_args[0][0]
+        assert helper._window == []

test/test_starlark_display_contract.py

@@ -0,0 +1,82 @@
+"""starlark-apps: display() must report what actually reached the panel.
+
+The display controller skips a mode only on a boolean False. Returning True
+after the frame update failed told it the mode had rendered, so it held a dead
+frame for the whole display_duration instead of rotating on -- the same class
+of defect as a display() that returns None.
+"""
+
+import sys
+from pathlib import Path
+from unittest.mock import MagicMock
+
+import pytest
+
+PLUGIN_DIR = Path(__file__).resolve().parent.parent / "plugin-repos" / "starlark-apps"
+
+
+@pytest.fixture(scope="module")
+def manager_module():
+    if not PLUGIN_DIR.exists():
+        pytest.skip("starlark-apps plugin is not checked out")
+    sys.path.insert(0, str(PLUGIN_DIR))
+    try:
+        import importlib
+        spec = importlib.util.spec_from_file_location(
+            "starlark_manager_under_test", PLUGIN_DIR / "manager.py")
+        module = importlib.util.module_from_spec(spec)
+        spec.loader.exec_module(module)
+        return module
+    except Exception as e:  # noqa: BLE001 - optional deps (pixlet, fcntl) may be absent
+        pytest.skip(f"starlark-apps manager is not importable here: {e}")
+    finally:
+        sys.path.remove(str(PLUGIN_DIR))
+
+
+def _plugin(manager_module):
+    """A manager with __init__ bypassed -- only display paths are under test."""
+    cls = manager_module.StarlarkAppsPlugin
+    inst = cls.__new__(cls)
+    inst.logger = MagicMock()
+    inst.display_manager = MagicMock()
+    inst.current_app = None
+    return inst
+
+
+class _App:
+    def __init__(self, frames):
+        self.frames = frames
+        self.current_frame_index = 0
+        self.last_frame_time = 0.0
+        self.app_id = "app"
+
+
+class TestDisplayFramePropagates:
+    def test_a_failed_update_returns_false(self, manager_module):
+        p = _plugin(manager_module)
+        p.current_app = _App([("frame", 100)])
+        p.display_manager.update_display.side_effect = RuntimeError("panel gone")
+
+        assert p._display_frame() is False
+
+    def test_a_good_update_returns_true(self, manager_module):
+        p = _plugin(manager_module)
+        p.current_app = _App([("frame", 100)])
+
+        assert p._display_frame() is True
+
+    def test_no_frames_returns_false(self, manager_module):
+        p = _plugin(manager_module)
+        p.current_app = _App([])
+
+        assert p._display_frame() is False
+
+    def test_display_reports_the_frame_failure(self, manager_module):
+        p = _plugin(manager_module)
+        p.current_app = _App([("frame", 100)])
+        p.display_manager.update_display.side_effect = RuntimeError("panel gone")
+
+        result = p.display()
+
+        assert result is False, "display() claimed success over a failed frame update"
+        assert isinstance(result, bool), "the controller only skips on a real bool"

test/web_interface/test_starlark_pixlet_routes.py

@@ -0,0 +1,395 @@
+"""The Starlark routes the frontend calls must exist.
+
+`plugins_manager.js` posts to /api/v3/starlark/install-pixlet and then reloads
+/api/v3/starlark/status. Neither route existed: #330 rewrote api_v3.py and
+dropped all thirteen Starlark routes that #253 had added, so both calls fell
+through to Flask's 404 handler, which answers
+
+    {"status": "error", "message": "Resource not found"}
+
+and the button reported "Pixlet install failed: Resource not found" -- a
+message that names neither the resource nor the cause.
+
+These assert the routes are registered and answer in the shape the frontend
+reads, so a future rewrite of this file cannot silently drop them again.
+"""
+
+import json
+import os
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+
+@pytest.fixture
+def client():
+    from web_interface.app import app
+    app.config['TESTING'] = True
+    with app.test_client() as c:
+        yield c
+
+
+class TestRoutesAreRegistered:
+    """The failure was a missing route, so check the URL map directly.
+
+    All thirteen, not just the two the Pixlet button needs: #330 dropped the
+    lot, and the app store page is built on repository/browse,
+    repository/categories and repository/install, which 404 the same way.
+    """
+
+    @pytest.mark.parametrize("rule,method", [
+        ("/api/v3/starlark/install-pixlet", "POST"),
+        ("/api/v3/starlark/status", "GET"),
+        ("/api/v3/starlark/apps", "GET"),
+        ("/api/v3/starlark/upload", "POST"),
+        ("/api/v3/starlark/repository/browse", "GET"),
+        ("/api/v3/starlark/repository/categories", "GET"),
+        ("/api/v3/starlark/repository/install", "POST"),
+        ("/api/v3/starlark/apps/<app_id>", "GET"),
+        ("/api/v3/starlark/apps/<app_id>", "DELETE"),
+        ("/api/v3/starlark/apps/<app_id>/config", "GET"),
+        ("/api/v3/starlark/apps/<app_id>/config", "PUT"),
+        ("/api/v3/starlark/apps/<app_id>/toggle", "POST"),
+        ("/api/v3/starlark/apps/<app_id>/render", "POST"),
+    ])
+    def test_route_exists(self, rule, method):
+        from web_interface.app import app
+        matches = [r for r in app.url_map.iter_rules()
+                   if r.rule == rule and method in r.methods]
+        assert matches, (
+            f"{method} {rule} is not registered; the frontend calls it and "
+            "would get Flask's generic 'Resource not found'")
+
+
+class TestInstallPixlet:
+    def test_it_does_not_404(self, client):
+        with patch('web_interface.blueprints.api_v3.subprocess.run') as run:
+            run.return_value = MagicMock(returncode=0, stdout="ok", stderr="")
+            resp = client.post('/api/v3/starlark/install-pixlet')
+        assert resp.status_code != 404, "the route is still missing"
+        assert resp.get_json().get('message') != 'Resource not found'
+
+    def test_success_is_reported_in_the_shape_the_button_reads(self, client):
+        with patch('web_interface.blueprints.api_v3.subprocess.run') as run:
+            run.return_value = MagicMock(returncode=0, stdout="done", stderr="")
+            resp = client.post('/api/v3/starlark/install-pixlet')
+        body = resp.get_json()
+        assert body['status'] == 'success', body
+        assert 'message' in body, "the JS shows data.message on success"
+
+    def test_a_failed_download_says_why(self, client):
+        with patch('web_interface.blueprints.api_v3.subprocess.run') as run:
+            run.return_value = MagicMock(returncode=1, stdout="", stderr="no such release")
+            resp = client.post('/api/v3/starlark/install-pixlet')
+        body = resp.get_json()
+        assert body['status'] == 'error'
+        assert 'no such release' in body['message'], \
+            "the installer's own stderr is what tells the user what went wrong"
+
+    def test_a_timeout_is_reported_rather_than_hanging(self, client):
+        import subprocess as sp
+        with patch('web_interface.blueprints.api_v3.subprocess.run',
+                   side_effect=sp.TimeoutExpired(cmd='x', timeout=300)):
+            resp = client.post('/api/v3/starlark/install-pixlet')
+        assert resp.get_json()['status'] == 'error'
+        assert 'timed out' in resp.get_json()['message'].lower()
+
+
+class TestStarlarkStatus:
+    def test_it_does_not_404(self, client):
+        resp = client.get('/api/v3/starlark/status')
+        assert resp.status_code != 404, "the route is still missing"
+        assert resp.get_json().get('message') != 'Resource not found'
+
+    def test_it_reports_pixlet_availability_without_the_plugin_loaded(self, client):
+        # The status call runs before install too -- it must answer even when
+        # starlark-apps is not loaded, which is the state a user is in when
+        # they press the install button for the first time.
+        with patch('web_interface.blueprints.api_v3._get_starlark_plugin', return_value=None):
+            resp = client.get('/api/v3/starlark/status')
+        body = resp.get_json()
+        assert body['status'] == 'success', body
+        assert 'pixlet_available' in body
+        assert body['plugin_loaded'] is False
+
+
+class TestTheInstallerScriptIsActuallyThere:
+    def test_download_pixlet_script_exists_and_is_executable(self):
+        # install_pixlet chmods and runs this; a missing file is the one error
+        # it reports as a 404 of its own, which would look identical to the
+        # bug being fixed here.
+        import os
+        from pathlib import Path
+        from web_interface.blueprints.api_v3 import PROJECT_ROOT
+        script = Path(PROJECT_ROOT) / 'scripts' / 'download_pixlet.sh'
+        assert script.is_file(), f"{script} is missing; install_pixlet would 404"
+        assert os.access(script, os.R_OK)
+
+
+class TestTheAppStoreFlow:
+    """Browsing and installing from the Tronbyte repository.
+
+    These are the calls the app store page makes. Each returned the generic
+    "Resource not found" before this change, which is indistinguishable from
+    an empty store.
+    """
+
+    @pytest.fixture
+    def offline_repo(self):
+        """No live GitHub calls from the test suite.
+
+        browse and categories reach _get_tronbyte_repository_class() and then
+        list_all_apps_cached(); with a cold server-side cache that is a real
+        network request, which makes the run slow, rate-limitable, and able to
+        pass on a 500 because these assertions only check for a 404.
+        """
+        repo = MagicMock()
+        # Matches what the real list_all_apps_cached returns; the handler
+        # indexes every one of these keys.
+        repo.return_value.list_all_apps_cached.return_value = {
+            'apps': [{'id': 'quoteoftheday', 'name': 'A Quote A Day',
+                      'category': 'text'}],
+            'categories': ['text'],
+            'authors': ['someone'],
+            'count': 1,
+            'cached': True,
+        }
+        repo.return_value.get_rate_limit_info.return_value = {'remaining': 5000}
+        with patch('web_interface.blueprints.api_v3._get_tronbyte_repository_class',
+                   return_value=repo):
+            yield repo
+
+    def test_browse_does_not_404(self, client, offline_repo):
+        resp = client.get('/api/v3/starlark/repository/browse')
+        assert resp.status_code != 404, "the store cannot list anything"
+        assert resp.get_json().get('message') != 'Resource not found'
+
+    def test_browse_returns_the_apps_the_store_lists(self, client, offline_repo):
+        resp = client.get('/api/v3/starlark/repository/browse')
+        body = resp.get_json()
+        assert body['status'] == 'success', body
+        assert any(a.get('id') == 'quoteoftheday' for a in body.get('apps', [])), body
+
+    def test_categories_does_not_404(self, client, offline_repo):
+        resp = client.get('/api/v3/starlark/repository/categories')
+        assert resp.status_code != 404
+        assert resp.get_json().get('message') != 'Resource not found'
+
+    def test_no_live_network_call_is_made(self, client, offline_repo):
+        client.get('/api/v3/starlark/repository/browse')
+        assert offline_repo.called, \
+            "the route did not go through the patched repository class"
+
+    def test_installed_apps_list_does_not_404(self, client):
+        resp = client.get('/api/v3/starlark/apps')
+        assert resp.status_code != 404
+        assert resp.get_json().get('message') != 'Resource not found'
+
+    def test_repository_install_rejects_a_missing_body_rather_than_404ing(self, client):
+        # A 400/422 here is the route working: it received the call and said
+        # what was wrong. A 404 means it was never reached at all.
+        resp = client.post('/api/v3/starlark/repository/install',
+                           json={}, content_type='application/json')
+        assert resp.status_code != 404, "the install route is still missing"
+        assert resp.get_json().get('message') != 'Resource not found'
+
+    def test_upload_rejects_an_empty_post_rather_than_404ing(self, client):
+        resp = client.post('/api/v3/starlark/upload')
+        assert resp.status_code != 404
+        assert resp.get_json().get('message') != 'Resource not found'
+
+
+class TestNoStarlarkRouteIsMissing:
+    """A single check that the whole set is present.
+
+    #330 removed all thirteen at once by rewriting this file. One assertion
+    over the frontend's own list is what would have caught that.
+    """
+
+    def test_every_endpoint_the_frontend_calls_is_registered(self):
+        import re
+        from pathlib import Path
+        from werkzeug.exceptions import MethodNotAllowed, NotFound
+        from web_interface.app import app
+
+        root = Path(__file__).resolve().parent.parent.parent
+        js = (root / 'web_interface' / 'static' / 'v3' / 'plugins_manager.js').read_text()
+
+        # The frontend builds some of these with template literals, e.g.
+        # `/api/v3/starlark/apps/${appId}/toggle`. Substitute a placeholder so
+        # the URL is concrete, then let Werkzeug match it the way a request
+        # would -- string comparison cannot see <app_id> rules.
+        raw = set(re.findall(r"[\'\"`](/api/v3/starlark/[^\'\"`\s]*)", js))
+        urls = set()
+        for u in raw:
+            u = re.sub(r"\$\{[^}]*\}", "probe", u)
+            urls.add(u.rstrip('/') or u)
+        assert urls, "found no starlark calls in the frontend -- did the file move?"
+
+        adapter = app.url_map.bind('localhost')
+        missing = []
+        for u in sorted(urls):
+            try:
+                adapter.match(u, method='GET')
+            except MethodNotAllowed:
+                pass          # route exists, just not for GET -- fine
+            except NotFound:
+                missing.append(u)
+        assert not missing, f"the frontend calls these and they are not registered: {missing}"
+
+
+class TestInstalledAppsAppearWithTheOtherPlugins:
+    """An installed .star app must be manageable like any other plugin.
+
+    #253 surfaced installed apps in /plugins/installed as `starlark:<app_id>`
+    entries, so they could be seen and enabled/disabled from the same list as
+    everything else, and routed `starlark:` toggles to the Starlark manifest.
+    #330 removed both. The result was an app that installs successfully, then
+    appears nowhere and cannot be turned on or off.
+    """
+
+    APPS = {'apps': {'quoteoftheday': {'name': 'A Quote A Day', 'enabled': True}}}
+
+    def test_an_installed_app_is_listed(self, client):
+        with patch('web_interface.blueprints.api_v3._get_starlark_plugin', return_value=None), \
+             patch('web_interface.blueprints.api_v3._read_starlark_manifest', return_value=self.APPS):
+            resp = client.get('/api/v3/plugins/installed')
+        ids = [p['id'] for p in resp.get_json()['data']['plugins']]
+        assert 'starlark:quoteoftheday' in ids, \
+            "an installed Starlark app does not appear among the plugins"
+
+    def test_the_entry_carries_what_the_ui_needs(self, client):
+        with patch('web_interface.blueprints.api_v3._get_starlark_plugin', return_value=None), \
+             patch('web_interface.blueprints.api_v3._read_starlark_manifest', return_value=self.APPS):
+            resp = client.get('/api/v3/plugins/installed')
+        entry = next(p for p in resp.get_json()['data']['plugins']
+                     if p['id'] == 'starlark:quoteoftheday')
+        assert entry['name'] == 'A Quote A Day'
+        assert entry['enabled'] is True
+        assert entry['is_starlark_app'] is True, "the UI keys its Starlark handling off this"
+        assert entry['category'] == 'Starlark App'
+
+    def test_a_starlark_failure_does_not_empty_the_plugin_list(self, client):
+        # The virtual entries are appended to the real ones; a broken manifest
+        # must cost the Starlark rows, not everybody else's.
+        with patch('web_interface.blueprints.api_v3._get_starlark_plugin',
+                   side_effect=RuntimeError('boom')):
+            resp = client.get('/api/v3/plugins/installed')
+        assert resp.status_code == 200
+        assert resp.get_json()['status'] == 'success'
+
+    def test_toggling_an_app_does_not_report_plugin_not_found(self, client):
+        written = {}
+        with patch('web_interface.blueprints.api_v3._get_starlark_plugin', return_value=None), \
+             patch('web_interface.blueprints.api_v3._read_starlark_manifest',
+                   return_value={'apps': {'quoteoftheday': {'enabled': True}}}), \
+             patch('web_interface.blueprints.api_v3._write_starlark_manifest',
+                   side_effect=lambda m: written.update(m) or True):
+            resp = client.post('/api/v3/plugins/toggle',
+                               json={'plugin_id': 'starlark:quoteoftheday', 'enabled': False})
+        body = resp.get_json()
+        assert body['status'] == 'success', body
+        assert body['enabled'] is False
+        assert written['apps']['quoteoftheday']['enabled'] is False, \
+            "the manifest was not actually updated"
+
+    def test_toggling_an_unknown_app_says_so(self, client):
+        with patch('web_interface.blueprints.api_v3._get_starlark_plugin', return_value=None), \
+             patch('web_interface.blueprints.api_v3._read_starlark_manifest',
+                   return_value={'apps': {}}):
+            resp = client.post('/api/v3/plugins/toggle',
+                               json={'plugin_id': 'starlark:nope', 'enabled': True})
+        assert resp.status_code == 404
+        assert 'nope' in resp.get_json()['message']
+
+    def test_a_traversal_app_id_is_rejected_before_touching_the_manifest(self, client):
+        resp = client.post('/api/v3/plugins/toggle',
+                           json={'plugin_id': 'starlark:../../etc/passwd', 'enabled': True})
+        assert resp.status_code == 400
+        assert 'traversal' in resp.get_json()['message']
+
+    def test_an_app_id_the_listing_published_can_be_toggled(self, client):
+        """The id here is exactly what _starlark_virtual_plugins publishes.
+
+        It used to be re-slugified on the way back in -- lowercased, with every
+        character outside [a-z0-9_] replaced -- so an app stored as 'My-App'
+        was listed as 'starlark:My-App' and looked up as 'my_app'. Toggling an
+        app the page had just drawn answered 404.
+        """
+        manifest = {'apps': {'My-App': {'name': 'My App', 'enabled': False}}}
+        with patch('web_interface.blueprints.api_v3._get_starlark_plugin', return_value=None), \
+             patch('web_interface.blueprints.api_v3._read_starlark_manifest',
+                   return_value=manifest), \
+             patch('web_interface.blueprints.api_v3._write_starlark_manifest',
+                   return_value=True) as write:
+            resp = client.post('/api/v3/plugins/toggle',
+                               json={'plugin_id': 'starlark:My-App', 'enabled': True})
+        assert resp.status_code == 200, resp.get_json()
+        assert write.called, "the toggle never reached the manifest"
+        assert manifest['apps']['My-App']['enabled'] is True
+
+    def test_a_loaded_app_missing_from_the_manifest_does_not_500(self, client):
+        """_update_manifest_safe does not catch KeyError, so indexing an entry
+        that is not on disk yet escaped as a 500 instead of writing it."""
+        app = MagicMock()
+        app.manifest = {'enabled': False}
+        plugin = MagicMock()
+        plugin.apps = {'demo': app}
+        written = {}
+
+        def run_updater(fn):
+            fn(written)
+            return True
+
+        plugin._update_manifest_safe.side_effect = run_updater
+
+        with patch('web_interface.blueprints.api_v3._get_starlark_plugin', return_value=plugin):
+            resp = client.post('/api/v3/plugins/toggle',
+                               json={'plugin_id': 'starlark:demo', 'enabled': True})
+        assert resp.status_code == 200, resp.get_json()
+        assert written['apps']['demo']['enabled'] is True
+
+
+class TestTheManifestStaysRelocatable:
+    """`star_file` is joined to the app's own directory by its readers.
+
+    _standalone_render_starlark_app does `app_dir / app_data.get('star_file',
+    f'{app_id}.star')`, so the key's default is a bare filename. Storing an
+    absolute path gave it a second meaning, and Path.__truediv__ discards the
+    left side when the right is absolute -- which pinned the manifest to the
+    PROJECT_ROOT that installed it.
+    """
+
+    @pytest.fixture
+    def starlark_dir(self, tmp_path, monkeypatch):
+        from web_interface.blueprints import api_v3 as module
+        apps_dir = tmp_path / "starlark-apps"
+        apps_dir.mkdir()
+        monkeypatch.setattr(module, '_STARLARK_APPS_DIR', apps_dir)
+        monkeypatch.setattr(module, '_STARLARK_MANIFEST_FILE', apps_dir / 'manifest.json')
+        return apps_dir
+
+    def _install(self, tmp_path):
+        from web_interface.blueprints import api_v3 as module
+        source = tmp_path / "source.star"
+        source.write_text("# app")
+        with patch.object(module, '_get_pixlet_renderer_class',
+                          side_effect=ImportError("no pixlet here")):
+            assert module._install_star_file('demo', str(source), {'name': 'Demo'})
+        return json.loads((module._STARLARK_MANIFEST_FILE).read_text())['apps']['demo']
+
+    def test_the_star_file_is_recorded_by_name(self, starlark_dir, tmp_path):
+        assert self._install(tmp_path)['star_file'] == 'demo.star'
+
+    def test_the_recorded_path_is_not_absolute(self, starlark_dir, tmp_path):
+        """An absolute value survives a move only by accident."""
+        assert not os.path.isabs(self._install(tmp_path)['star_file'])
+
+    def test_the_value_resolves_against_the_app_directory(self, starlark_dir, tmp_path):
+        """Which is the one thing every reader of this key does with it."""
+        entry = self._install(tmp_path)
+        assert (starlark_dir / 'demo' / entry['star_file']).is_file()
+
+    def test_it_matches_the_default_a_reader_falls_back_to(self, starlark_dir, tmp_path):
+        """Stored and defaulted values must mean the same thing."""
+        assert self._install(tmp_path)['star_file'] == 'demo.star'

web_interface/app.py

@@ -83,11 +83,11 @@ plugin_system_config = config.get('plugin_system', {})
 plugins_dir_name = plugin_system_config.get('plugins_directory', 'plugin-repos')
 
 # Resolve plugin directory - handle both absolute and relative paths
-project_root = Path(__file__).parent.parent
 if os.path.isabs(plugins_dir_name):
     plugins_dir = Path(plugins_dir_name)
 else:
     # If relative, resolve relative to the project root (LEDMatrix directory)
+    project_root = Path(__file__).parent.parent
     plugins_dir = project_root / plugins_dir_name
 
 plugin_manager = PluginManager(
@@ -157,7 +157,6 @@ _health_monitor_initialized = False
 # Register blueprints
 from web_interface.blueprints.pages_v3 import pages_v3
 from web_interface.blueprints.api_v3 import api_v3
-from web_interface.blueprints.composer import composer_bp
 
 # Initialize managers in blueprints
 pages_v3.config_manager = config_manager
@@ -174,11 +173,6 @@ api_v3.operation_queue = operation_queue
 api_v3.plugin_state_manager = plugin_state_manager
 api_v3.operation_history = operation_history
 api_v3.health_monitor = health_monitor
-
-composer_bp.config_manager = config_manager
-composer_bp.plugin_manager = plugin_manager
-composer_bp.plugins_dir = plugins_dir
-composer_bp.project_root = project_root
 # Initialize cache manager for API endpoints
 from src.cache_manager import CacheManager
 api_v3.cache_manager = CacheManager()
@@ -206,7 +200,6 @@ except Exception as _hm_err:  # pragma: no cover - defensive startup guard
 app.register_blueprint(pages_v3, url_prefix='')
 app.register_blueprint(pages_v3, url_prefix='/v3', name='pages_v3_legacy')
 app.register_blueprint(api_v3, url_prefix='/api/v3')
-app.register_blueprint(composer_bp, url_prefix='/composer')
 
 # Route to serve plugin asset files (registered on main app, not blueprint, for /assets/... path)
 @app.route('/assets/plugins/<plugin_id>/uploads/<path:filename>', methods=['GET'])

web_interface/static/v3/app.css

@@ -426,9 +426,6 @@ a, button, input, select, textarea {
     .md\:hidden { display: none; }
     .md\:block { display: block; }
     .md\:w-auto { width: auto; }
-    /* composer.html labels its toolbar buttons `hidden md:inline`, so without
-       this the label is hidden at every width and the buttons stay icon-only. */
-    .md\:inline { display: inline; }
 }
 
 @media (min-width: 1024px) {

web_interface/static/v3/js/composer/composer-canvas.js

@@ -1,817 +0,0 @@
-/**
- * ComposerCanvas — stateless LED matrix canvas renderer.
- *
- * Coordinate system: LED pixels (integers). All drawing multiplies by SCALE.
- * PIL draw.text(x,y) is top-left; canvas fillText(x,y) is baseline.
- *   → Canvas text cy = (actualY + fontSizePx) * SCALE
- *
- * Anchors: element x/y are offsets from their anchor point:
- *   xAnchor=null/'left'  → x is fixed offset from left
- *   xAnchor='center'     → x is offset from width/2
- *   xAnchor='right'      → x is offset inward from right edge
- *   yAnchor follows the same pattern with 'top'/'middle'/'bottom'
- *
- * Breakpoints: elements with minWidth > currentMatrixW are rendered at 25% opacity.
- *
- * Resize handles: drawn on selected rectangles; 8 handles (corners + edge mids).
- */
-/* eslint-disable security/detect-object-injection --
-   Every hit in this file is either an array index (this.elements[idx],
-   rawVals[i]) or a lookup on a module-private map keyed by an internal
-   element type (_HANDLE_CURSORS, ELEMENT_DEFAULTS, previewValues). None of
-   them takes an attacker-supplied property name, so none can reach a
-   prototype. Disabled per file rather than eight times inline. */
-window.ComposerCanvas = (() => {
-  'use strict';
-
-  let _canvas = null;
-  let _ctx = null;
-  let _showGrid = true;
-
-  //: Element types the canvas draws resize handles for. Exported because the
-  //: editor has to gate its resize and hover behaviour on exactly this list --
-  //: the two had drifted, so handles appeared on five shapes that could not
-  //: actually be resized.
-  const RESIZABLE_TYPES = ['rectangle', 'rounded_rectangle', 'ellipse', 'arc',
-                           'gauge', 'sparkline'];
-
-  const DISPLAY_PRESETS = [
-    { label: '64×32',   w: 64,  h: 32 },
-    { label: '128×32',  w: 128, h: 32 },
-    { label: '128×64',  w: 128, h: 64 },
-    { label: '256×32',  w: 256, h: 32 },
-    { label: '256×64',  w: 256, h: 64 },
-  ];
-
-  const FONT_MAP = {
-    press_start:   { family: "'PressStart2P', monospace", sizePx: 8,  charW: 8 },
-    four_by_six:   { family: 'monospace',                sizePx: 6,  charW: 4 },
-    five_by_seven: { family: 'monospace',                sizePx: 7,  charW: 5 },
-  };
-
-  const ELEMENT_DEFAULTS = {
-    text: {
-      text: 'Hello', font: 'press_start',
-      r: 255, g: 255, b: 255,
-      text2: '', lineSpacing: 2, textAlign: 'left',
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    dynamic_text: {
-      binding: { source: 'config', key: '', format: null },
-      font: 'press_start', textAlign: 'left',
-      r: 255, g: 200, b: 100,
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    clock: {
-      format: '%H:%M', font: 'press_start',
-      r: 100, g: 255, b: 100,
-      format2: '', lineSpacing: 2, textAlign: 'left',
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    rectangle: {
-      width: 20, height: 8,
-      fillR: 0, fillG: 0, fillB: 128, hasFill: true,
-      outR: 255, outG: 255, outB: 255, hasOutline: true,
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    ellipse: {
-      width: 24, height: 12,
-      fillR: 0, fillG: 100, fillB: 200, hasFill: true,
-      outR: 100, outG: 180, outB: 255, hasOutline: true,
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    arc: {
-      width: 24, height: 24,
-      startAngle: 0, endAngle: 270, lineWidth: 2,
-      r: 255, g: 200, b: 0,
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    pixel: {
-      r: 255, g: 255, b: 255,
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    rounded_rectangle: {
-      width: 24, height: 10, borderRadius: 3,
-      fillR: 0, fillG: 80, fillB: 180, hasFill: true,
-      outR: 120, outG: 180, outB: 255, hasOutline: true,
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    line: {
-      x0: 0, y0: 16, x1: 63, y1: 16,
-      r: 180, g: 180, b: 180, lineWidth: 1,
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    divider: {
-      orientation: 'horizontal', y: 16, x: 64,
-      r: 100, g: 100, b: 100,
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    progress_bar: {
-      barWidth: 60, barHeight: 6,
-      binding: { source: 'config', key: '', format: null },
-      r: 80, g: 200, b: 80,
-      bgR: 30, bgG: 30, bgB: 30, hasBg: true,
-      outR: 100, outG: 100, outB: 100, hasOutline: true,
-      previewPct: 65,
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    countdown: {
-      binding: { source: 'config', key: '', format: null },
-      countdownFormat: 'dh',
-      font: 'four_by_six', textAlign: 'left',
-      r: 255, g: 180, b: 0,
-      previewText: '42d 3h',
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    marquee: {
-      text: 'Scrolling text', font: 'press_start',
-      r: 255, g: 255, b: 255,
-      scrollSpeed: 1, gap: 16, direction: 'left',
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    section: {
-      label: 'Section',
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    pips: {
-      count: 5, filled: 3, pipSize: 4, pipSpacing: 2,
-      r: 255, g: 200, b: 0,
-      emptyR: 50, emptyG: 50, emptyB: 50, showEmpty: true,
-      binding: { source: 'config', key: '', format: null },
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    sparkline: {
-      width: 40, height: 12,
-      barCount: 8, barSpacing: 1,
-      r: 80, g: 200, b: 120,
-      bgR: 30, bgG: 30, bgB: 30, hasBg: false,
-      binding: { source: 'config', key: '', format: null },
-      previewData: '0.3,0.6,0.4,0.8,0.5,0.9,0.7,0.85',
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-    gauge: {
-      width: 32, height: 32,
-      startAngle: 135, endAngle: 45, lineWidth: 3,
-      binding: { source: 'config', key: '', format: null },
-      r: 80, g: 220, b: 80,
-      trackR: 40, trackG: 40, trackB: 40, hasTrack: true,
-      showLabel: true, font: 'four_by_six', labelR: 200, labelG: 200, labelB: 200,
-      previewPct: 65,
-      xAnchor: null, yAnchor: null, minWidth: 0, locked: false, blink: false, visible: true,
-    },
-  };
-
-  // ── Anchor resolution ────────────────────────────────────────────────
-  function resolveAnchor(val, anchor, dim) {
-    if (!anchor || anchor === 'left' || anchor === 'top') return val;
-    if (anchor === 'center' || anchor === 'middle') return Math.floor(dim / 2) + val;
-    if (anchor === 'right' || anchor === 'bottom') return dim - val;
-    return val;
-  }
-
-  function computeActualPos(el, matrixW, matrixH) {
-    const ax = resolveAnchor(el.x ?? el.x0 ?? 0, el.xAnchor, matrixW);
-    const ay = resolveAnchor(el.y ?? el.y0 ?? 0, el.yAnchor, matrixH);
-    return { x: ax, y: ay };
-  }
-
-  // ── Bounding box (LED pixel space) ──────────────────────────────────
-  function getBoundingBox(el, matrixW, matrixH) {
-    const { x: ax, y: ay } = computeActualPos(el, matrixW, matrixH);
-    const finfo = FONT_MAP[el.font] || FONT_MAP.press_start;
-
-    switch (el.type) {
-      case 'text': {
-        const t1 = el.text || '', t2 = el.text2 || '';
-        const w = Math.max(t1.length, t2.length) * finfo.charW;
-        const h = t2 ? finfo.sizePx * 2 + (el.lineSpacing ?? 2) : finfo.sizePx;
-        const bx = el.textAlign === 'center' ? ax - w / 2 : el.textAlign === 'right' ? ax - w : ax;
-        return { x: bx, y: ay, w, h };
-      }
-      case 'dynamic_text': {
-        const key = el.binding?.key || '?';
-        const w = (`{${key}}`).length * finfo.charW;
-        const bx = el.textAlign === 'center' ? ax - w / 2 : el.textAlign === 'right' ? ax - w : ax;
-        return { x: bx, y: ay, w, h: finfo.sizePx };
-      }
-      case 'clock': {
-        const t1 = el.format || '%H:%M', t2 = el.format2 || '';
-        const w = Math.max(t1.length, t2.length) * finfo.charW;
-        const h = t2 ? finfo.sizePx * 2 + (el.lineSpacing ?? 2) : finfo.sizePx;
-        const bx = el.textAlign === 'center' ? ax - w / 2 : el.textAlign === 'right' ? ax - w : ax;
-        return { x: bx, y: ay, w, h };
-      }
-      case 'countdown': {
-        const pt = el.previewText || '--d --h';
-        const w = pt.length * finfo.charW;
-        const bx = el.textAlign === 'center' ? ax - w / 2 : el.textAlign === 'right' ? ax - w : ax;
-        return { x: bx, y: ay, w, h: finfo.sizePx };
-      }
-      case 'rectangle':
-      case 'rounded_rectangle':
-      case 'ellipse':
-      case 'arc':
-        return { x: ax, y: ay, w: el.width, h: el.height };
-      case 'pixel':
-        return { x: ax, y: ay, w: 1, h: 1 };
-      case 'line': {
-        // Same anchor offset the draw path applies, or the hit box sits where
-        // the line used to be.
-        const dx = ax - el.x0, dy = ay - el.y0;
-        return {
-          x: Math.min(el.x0, el.x1) + dx, y: Math.min(el.y0, el.y1) + dy,
-          w: Math.max(1, Math.abs(el.x1 - el.x0)),
-          h: Math.max(1, Math.abs(el.y1 - el.y0)),
-        };
-      }
-      case 'divider':
-        return el.orientation === 'horizontal'
-          ? { x: 0,  y: ay, w: matrixW, h: 1 }
-          : { x: ax, y: 0,  w: 1,       h: matrixH };
-      case 'progress_bar':
-        return { x: ax, y: ay, w: el.barWidth ?? 60, h: el.barHeight ?? 6 };
-      case 'marquee': {
-        const mfinfo = FONT_MAP[el.font] || FONT_MAP.press_start;
-        return { x: 0, y: ay, w: matrixW, h: mfinfo.sizePx };
-      }
-      case 'gauge':
-        return { x: ax, y: ay, w: el.width ?? 32, h: el.height ?? 32 };
-      case 'sparkline':
-        return { x: ax, y: ay, w: el.width ?? 40, h: el.height ?? 12 };
-      case 'pips': {
-        const pc = el.count ?? 5, ps = el.pipSize ?? 4, pg = el.pipSpacing ?? 2;
-        return { x: ax, y: ay, w: pc * ps + (pc - 1) * pg, h: ps };
-      }
-      case 'section': {
-        // Was 0x0, so the element was unselectable except through the 3px
-        // hit-test padding and drew nothing at all -- a user adding one from
-        // the palette saw an empty canvas.
-        // Same font resolution as the draw case below, or the box will not
-        // match the glyphs: getBoundingBox's shared `finfo` falls back to
-        // press_start, and a section has no font of its own.
-        const sinfo = FONT_MAP[el.font] || FONT_MAP.four_by_six;
-        const label = el.label || 'Section';
-        return { x: ax, y: ay, w: label.length * sinfo.charW, h: sinfo.sizePx };
-      }
-      default:
-        return { x: ax, y: ay, w: 4, h: 4 };
-    }
-  }
-
-  // ── Resize handle support ─────────────────────────────────────────────
-  // Returns 8 handle points for a rectangle in LED pixel space
-  function _getRectHandles(el, matrixW, matrixH) {
-    const { x: ax, y: ay } = computeActualPos(el, matrixW, matrixH);
-    const w = el.width, h = el.height;
-    const cx = ax + w / 2, cy = ay + h / 2;
-    return {
-      nw: { x: ax,      y: ay      },
-      n:  { x: cx,      y: ay      },
-      ne: { x: ax + w,  y: ay      },
-      w:  { x: ax,      y: cy      },
-      e:  { x: ax + w,  y: cy      },
-      sw: { x: ax,      y: ay + h  },
-      s:  { x: cx,      y: ay + h  },
-      se: { x: ax + w,  y: ay + h  },
-    };
-  }
-
-  // Returns the handle direction under LED-space point (lx, ly), or null
-  function getResizeHandle(el, lx, ly, matrixW, matrixH) {
-    if (!RESIZABLE_TYPES.includes(el.type)) return null;
-    const handles = _getRectHandles(el, matrixW, matrixH);
-    const PAD = 4;
-    for (const [dir, pt] of Object.entries(handles)) {
-      if (Math.abs(lx - pt.x) <= PAD && Math.abs(ly - pt.y) <= PAD) return dir;
-    }
-    return null;
-  }
-
-  const _HANDLE_CURSORS = {
-    nw: 'nw-resize', n: 'n-resize', ne: 'ne-resize',
-    w: 'w-resize', e: 'e-resize',
-    sw: 'sw-resize', s: 's-resize', se: 'se-resize',
-  };
-  function getCursorForHandle(handle) {
-    return _HANDLE_CURSORS[handle] || 'crosshair';
-  }
-
-  // ── Hit test ─────────────────────────────────────────────────────────
-  function hitTest(el, lx, ly, matrixW, matrixH) {
-    const PAD = 3;
-    const bb = getBoundingBox(el, matrixW, matrixH);
-    return (
-      lx >= bb.x - PAD && lx <= bb.x + bb.w + PAD &&
-      ly >= bb.y - PAD && ly <= bb.y + bb.h + PAD
-    );
-  }
-
-  // ── Draw a single element ─────────────────────────────────────────────
-  function _drawElement(ctx, el, SCALE, matrixW, matrixH, opts = {}) {
-    const s = SCALE;
-    const { x: ax, y: ay } = computeActualPos(el, matrixW, matrixH);
-    const belowBreakpoint = el.minWidth > 0 && matrixW < el.minWidth;
-    const hidden = el.visible === false;
-
-    ctx.save();
-    if (hidden) ctx.globalAlpha = 0.12;
-    else if (belowBreakpoint) ctx.globalAlpha = 0.25;
-
-    // Blink animation: when blinkOff, fully hide blinking elements
-    if (el.blink) {
-      if (opts.blinkOff) { ctx.restore(); return; }
-      ctx.globalAlpha *= 0.55;
-    }
-
-    // Helper: compute draw X for text alignment
-    // biome-ignore lint/correctness/useQwikValidLexicalScope: not Qwik -- this is an Alpine.js component, and the rule is about Qwik's $() serialization boundary, which does not exist here.
-    const _textX = (text, finfo) => {
-      const tw = text.length * finfo.charW * s;
-      if (el.textAlign === 'center') return ax * s - tw / 2;
-      if (el.textAlign === 'right')  return ax * s - tw;
-      return ax * s;
-    };
-
-    try {
-      switch (el.type) {
-        case 'section': {
-          // A design-time label: it marks a region for the author and is not
-          // emitted into the generated plugin. There was no case here at all,
-          // so adding "Section Label" from the palette drew nothing and left
-          // the user with an apparently broken control.
-          const sfinfo = FONT_MAP[el.font] || FONT_MAP.four_by_six;
-          ctx.font = `${sfinfo.sizePx * s}px ${sfinfo.family}`;
-          ctx.fillStyle = `rgba(${el.r ?? 120},${el.g ?? 120},${el.b ?? 120},0.85)`;
-          ctx.textBaseline = 'top';
-          ctx.fillText(el.label || 'Section', ax * s, ay * s);
-          break;
-        }
-        case 'text':
-        case 'dynamic_text':
-        case 'clock': {
-          const finfo = FONT_MAP[el.font] || FONT_MAP.press_start;
-          const key = el.binding?.key || '?';
-          const pv = opts.previewValues?.[key];
-          // Substitute {variable} tokens in text using previewValues
-          // biome-ignore lint/correctness/useQwikValidLexicalScope: not Qwik -- this is an Alpine.js component, and the rule is about Qwik's $() serialization boundary, which does not exist here.
-          const _subVars = str => (str || '').replace(/\{(\w+)\}/g, (_, k) => {
-            const v = opts.previewValues?.[k];
-            return v !== undefined && v !== '' ? String(v) : `{${k}}`;
-          });
-          const displayText =
-            el.type === 'text'    ? _subVars(el.text || '')
-            : el.type === 'clock' ? (el.format || '%H:%M')
-            : (pv !== undefined && pv !== '' ? String(pv) : `{${key}}`);
-          ctx.font = `${finfo.sizePx * s}px ${finfo.family}`;
-          ctx.fillStyle = `rgb(${el.r},${el.g},${el.b})`;
-          ctx.fillText(displayText, _textX(displayText, finfo), (ay + finfo.sizePx) * s);
-          // Second line (text and clock)
-          if (el.type === 'text' && el.text2) {
-            const t2 = _subVars(el.text2);
-            const y2 = ay + finfo.sizePx + (el.lineSpacing ?? 2);
-            ctx.fillText(t2, _textX(t2, finfo), (y2 + finfo.sizePx) * s);
-          }
-          if (el.type === 'clock' && el.format2) {
-            const y2 = ay + finfo.sizePx + (el.lineSpacing ?? 2);
-            ctx.fillText(el.format2, _textX(el.format2, finfo), (y2 + finfo.sizePx) * s);
-          }
-          break;
-        }
-
-        case 'countdown': {
-          const finfo = FONT_MAP[el.font] || FONT_MAP.press_start;
-          const t = el.previewText || '--d --h';
-          ctx.font = `${finfo.sizePx * s}px ${finfo.family}`;
-          ctx.fillStyle = `rgb(${el.r},${el.g},${el.b})`;
-          ctx.fillText(t, _textX(t, finfo), (ay + finfo.sizePx) * s);
-          break;
-        }
-
-        case 'rectangle': {
-          const rx = ax * s, ry = ay * s;
-          const rw = el.width * s, rh = el.height * s;
-          if (el.hasFill) {
-            ctx.fillStyle = `rgb(${el.fillR},${el.fillG},${el.fillB})`;
-            ctx.fillRect(rx, ry, rw, rh);
-          }
-          if (el.hasOutline) {
-            ctx.strokeStyle = `rgb(${el.outR},${el.outG},${el.outB})`;
-            // 1 LED pixel, not 1 canvas pixel: at SCALE>1 an unscaled stroke
-            // renders thinner than the geometry it outlines.
-            ctx.lineWidth = s;
-            ctx.strokeRect(rx, ry, rw, rh);
-          }
-          break;
-        }
-
-        case 'ellipse': {
-          const cx = (ax + el.width / 2) * s;
-          const cy = (ay + el.height / 2) * s;
-          const lwPx = s;  // 1 LED pixel
-          // Inset by half the stroke, which straddles the path, so the outline
-          // stays within the element's bounds.
-          const rx = Math.max(0, (el.width / 2) * s - (el.hasOutline ? lwPx / 2 : 0));
-          const ry = Math.max(0, (el.height / 2) * s - (el.hasOutline ? lwPx / 2 : 0));
-          ctx.beginPath();
-          ctx.ellipse(cx, cy, rx, ry, 0, 0, Math.PI * 2);
-          if (el.hasFill) {
-            ctx.fillStyle = `rgb(${el.fillR},${el.fillG},${el.fillB})`;
-            ctx.fill();
-          }
-          if (el.hasOutline) {
-            ctx.strokeStyle = `rgb(${el.outR},${el.outG},${el.outB})`;
-            ctx.lineWidth = lwPx;
-            ctx.stroke();
-          }
-          break;
-        }
-
-        case 'arc': {
-          const cx = (ax + el.width / 2) * s;
-          const cy = (ay + el.height / 2) * s;
-          const lwPx = Math.max(1, el.lineWidth || 2) * s;
-          const rx = Math.max(0, (el.width / 2) * s - lwPx / 2);
-          const ry = Math.max(0, (el.height / 2) * s - lwPx / 2);
-          // PIL: 0°=right, clockwise. Canvas: same with anticlockwise=false
-          const startRad = (el.startAngle ?? 0) * Math.PI / 180;
-          const endRad = (el.endAngle ?? 270) * Math.PI / 180;
-          ctx.beginPath();
-          ctx.ellipse(cx, cy, rx, ry, 0, startRad, endRad, false);
-          ctx.strokeStyle = `rgb(${el.r},${el.g},${el.b})`;
-          ctx.lineWidth = lwPx;
-          ctx.stroke();
-          break;
-        }
-
-        case 'pixel': {
-          ctx.fillStyle = `rgb(${el.r},${el.g},${el.b})`;
-          ctx.fillRect(ax * s, ay * s, s, s);
-          break;
-        }
-
-        case 'rounded_rectangle': {
-          const rx = ax * s, ry = ay * s;
-          const rw = el.width * s, rh = el.height * s;
-          const rad = Math.min((el.borderRadius ?? 3) * s, rw / 2, rh / 2);
-          ctx.beginPath();
-          ctx.roundRect(rx, ry, rw, rh, rad);
-          if (el.hasFill) {
-            ctx.fillStyle = `rgb(${el.fillR},${el.fillG},${el.fillB})`;
-            ctx.fill();
-          }
-          if (el.hasOutline) {
-            ctx.strokeStyle = `rgb(${el.outR},${el.outG},${el.outB})`;
-            ctx.lineWidth = s;
-            ctx.stroke();
-          }
-          break;
-        }
-
-        case 'line': {
-          // ax/ay resolve from el.x0 for a line, so this is the anchor offset.
-          // Without it a line stayed put while every other type moved.
-          const dx = ax - el.x0, dy = ay - el.y0;
-          ctx.strokeStyle = `rgb(${el.r},${el.g},${el.b})`;
-          ctx.lineWidth = Math.max(1, el.lineWidth || 1) * s;
-          ctx.beginPath();
-          ctx.moveTo((el.x0 + dx) * s, (el.y0 + dy) * s);
-          ctx.lineTo((el.x1 + dx) * s, (el.y1 + dy) * s);
-          ctx.stroke();
-          break;
-        }
-
-        case 'divider': {
-          const isH = (el.orientation || 'horizontal') === 'horizontal';
-          ctx.strokeStyle = `rgb(${el.r},${el.g},${el.b})`;
-          ctx.lineWidth = s;
-          ctx.beginPath();
-          if (isH) {
-            ctx.moveTo(0, (ay + 0.5) * s);
-            ctx.lineTo(_canvas.width, (ay + 0.5) * s);
-          } else {
-            ctx.moveTo((ax + 0.5) * s, 0);
-            ctx.lineTo((ax + 0.5) * s, _canvas.height);
-          }
-          ctx.stroke();
-          break;
-        }
-
-        case 'pips': {
-          const pipCount = Math.max(1, el.count ?? 5);
-          const pvPips = opts.previewValues?.[el.binding?.key];
-          const filledN = pvPips !== undefined
-            ? Math.max(0, Math.min(pipCount, Math.round(parseFloat(pvPips) || 0)))
-            : Math.max(0, Math.min(pipCount, el.filled ?? 3));
-          const ps = Math.max(1, el.pipSize ?? 4);
-          const pg = Math.max(0, el.pipSpacing ?? 2);
-          for (let i = 0; i < pipCount; i++) {
-            const isFilled = i < filledN;
-            if (!isFilled && !el.showEmpty) continue;
-            ctx.fillStyle = isFilled
-              ? `rgb(${el.r},${el.g},${el.b})`
-              : `rgb(${el.emptyR ?? 50},${el.emptyG ?? 50},${el.emptyB ?? 50})`;
-            ctx.fillRect((ax + i * (ps + pg)) * s, ay * s, ps * s, ps * s);
-          }
-          break;
-        }
-
-        case 'sparkline': {
-          const slW = el.width ?? 40, slH = el.height ?? 12;
-          const count = Math.max(1, el.barCount ?? 8);
-          const spacing = el.barSpacing ?? 1;
-          const barW = Math.max(1, Math.floor((slW - spacing * (count - 1)) / count));
-          const rawVals = (el.previewData || '').split(',')
-            .map(v => parseFloat(v.trim())).filter(n => !isNaN(n));
-          while (rawVals.length < count) rawVals.push(0);
-          const maxV = Math.max(...rawVals.slice(0, count), 0.001);
-          const rx = ax * s, ry = ay * s;
-          if (el.hasBg) {
-            ctx.fillStyle = `rgb(${el.bgR ?? 30},${el.bgG ?? 30},${el.bgB ?? 30})`;
-            ctx.fillRect(rx, ry, slW * s, slH * s);
-          }
-          ctx.fillStyle = `rgb(${el.r},${el.g},${el.b})`;
-          for (let i = 0; i < count; i++) {
-            const norm = Math.max(0, Math.min(1, rawVals[i] / maxV));
-            const barH = Math.max(1, Math.round(slH * norm));
-            const bx = rx + (barW + spacing) * i * s;
-            const by = ry + (slH - barH) * s;
-            ctx.fillRect(bx, by, barW * s, barH * s);
-          }
-          break;
-        }
-
-        case 'gauge': {
-          const gw = (el.width ?? 32), gh = (el.height ?? 32);
-          const cx = (ax + gw / 2) * s, cy = (ay + gh / 2) * s;
-          const rx = (gw / 2) * s, ry = (gh / 2) * s;
-          const lw = Math.max(1, (el.lineWidth ?? 3));
-          // rx/ry are canvas pixels ((gw/2)*s) but lw is LED pixels, so
-          // insetting by lw/2 under-corrected by the scale factor while the
-          // stroke was drawn at lw*s -- the arc spilled outside the element's
-          // reported bounding box at any SCALE > 1, and the preview stopped
-          // matching the generated PIL output.
-          const lwPx = lw * s;
-          const startDeg = el.startAngle ?? 135;
-          const endDeg   = el.endAngle   ?? 45;
-          // Arc sweep: from startDeg clockwise to endDeg (PIL convention)
-          const totalSweep = ((endDeg - startDeg) + 360) % 360 || 360;
-          const pvGauge = opts.previewValues?.[el.binding?.key];
-          const pct = pvGauge !== undefined
-            ? Math.max(0, Math.min(100, parseFloat(pvGauge) || 0)) / 100
-            : Math.max(0, Math.min(100, el.previewPct ?? 65)) / 100;
-          const fillSweep = totalSweep * pct;
-          // A small imported gauge with a wide lineWidth would otherwise send
-          // a negative radius into ctx.ellipse(), which throws IndexSizeError
-          // and aborts the whole render() call.
-          const arx = Math.max(0, rx - lwPx / 2), ary = Math.max(0, ry - lwPx / 2);
-          // biome-ignore lint/correctness/useQwikValidLexicalScope: not Qwik -- this is an Alpine.js component, and the rule is about Qwik's $() serialization boundary, which does not exist here.
-          const toRad = deg => (deg - 90) * Math.PI / 180; // canvas 0=top, PIL 0=right → offset -90
-
-          // Track arc
-          if (el.hasTrack !== false) {
-            ctx.beginPath();
-            ctx.ellipse(cx, cy, arx, ary, 0, toRad(startDeg), toRad(startDeg + totalSweep), false);
-            ctx.strokeStyle = `rgb(${el.trackR ?? 40},${el.trackG ?? 40},${el.trackB ?? 40})`;
-            ctx.lineWidth = lwPx;
-            ctx.stroke();
-          }
-          // Fill arc
-          if (pct > 0) {
-            ctx.beginPath();
-            ctx.ellipse(cx, cy, arx, ary, 0, toRad(startDeg), toRad(startDeg + fillSweep), false);
-            ctx.strokeStyle = `rgb(${el.r},${el.g},${el.b})`;
-            ctx.lineWidth = lwPx;
-            ctx.stroke();
-          }
-          // Centre label
-          if (el.showLabel) {
-            const gfinfo = FONT_MAP[el.font || 'four_by_six'] || FONT_MAP.four_by_six;
-            const labelText = Math.round(pct * 100) + '%';
-            ctx.font = `${gfinfo.sizePx * s}px ${gfinfo.family}`;
-            ctx.fillStyle = `rgb(${el.labelR ?? 200},${el.labelG ?? 200},${el.labelB ?? 200})`;
-            const ltw = ctx.measureText(labelText).width;
-            ctx.fillText(labelText, cx - ltw / 2, cy + (gfinfo.sizePx * s) / 2);
-          }
-          break;
-        }
-
-        case 'marquee': {
-          const finfo = FONT_MAP[el.font] || FONT_MAP.press_start;
-          const text = el.text || 'Scrolling text';
-          const tw = text.length * finfo.charW * s;
-          const gap = (el.gap ?? 16) * s;
-          const totalW = tw + gap;
-          const tick = opts.animTick ?? 0;
-          const speed = (el.scrollSpeed ?? 1) * 2;
-          const scrolled = (tick * speed) % totalW;
-          // left: text enters from right; right: text enters from left
-          const startX = el.direction === 'right'
-            ? scrolled - tw
-            : matrixW * s - scrolled;
-          ctx.font = `${finfo.sizePx * s}px ${finfo.family}`;
-          ctx.fillStyle = `rgb(${el.r},${el.g},${el.b})`;
-          // Clip to canvas width so text doesn't bleed outside
-          ctx.save();
-          ctx.beginPath();
-          ctx.rect(0, ay * s - 1, matrixW * s, (finfo.sizePx + 2) * s);
-          ctx.clip();
-          for (let i = -1; i <= 2; i++) {
-            ctx.fillText(text, startX + i * totalW, (ay + finfo.sizePx) * s);
-          }
-          ctx.restore();
-          break;
-        }
-
-        case 'progress_bar': {
-          const bw = el.barWidth ?? 60, bh = el.barHeight ?? 6;
-          const pvPb = opts.previewValues?.[el.binding?.key];
-          const pct = pvPb !== undefined
-            ? Math.max(0, Math.min(100, parseFloat(pvPb) || 0)) / 100
-            : Math.max(0, Math.min(100, el.previewPct ?? 65)) / 100;
-          const rx = ax * s, ry = ay * s;
-          if (el.hasBg) {
-            ctx.fillStyle = `rgb(${el.bgR ?? 30},${el.bgG ?? 30},${el.bgB ?? 30})`;
-            ctx.fillRect(rx, ry, bw * s, bh * s);
-          }
-          const fillW = Math.max(0, Math.round(bw * pct));
-          if (fillW > 0) {
-            ctx.fillStyle = `rgb(${el.r},${el.g},${el.b})`;
-            ctx.fillRect(rx, ry, fillW * s, bh * s);
-          }
-          if (el.hasOutline) {
-            ctx.strokeStyle = `rgb(${el.outR ?? 100},${el.outG ?? 100},${el.outB ?? 100})`;
-            ctx.lineWidth = s;
-            ctx.strokeRect(rx, ry, bw * s, bh * s);
-          }
-          break;
-        }
-      }
-
-      if (belowBreakpoint) {
-        ctx.globalAlpha = 0.6;
-        const bb = getBoundingBox(el, matrixW, matrixH);
-        ctx.font = `${Math.max(8, s * 2)}px monospace`;
-        ctx.fillStyle = '#facc15';
-        ctx.fillText(`≥${el.minWidth}px`, bb.x * s, (bb.y + 4) * s);
-      }
-    } finally {
-      ctx.restore();
-    }
-  }
-
-  // ── Selection indicator ──────────────────────────────────────────────
-  function _drawSelection(ctx, el, SCALE, matrixW, matrixH) {
-    const bb = getBoundingBox(el, matrixW, matrixH);
-    const PAD = 2, s = SCALE;
-    const rx = bb.x * s - PAD, ry = bb.y * s - PAD;
-    const rw = bb.w * s + PAD * 2, rh = bb.h * s + PAD * 2;
-
-    ctx.save();
-    ctx.strokeStyle = '#3b82f6';
-    ctx.lineWidth = 1;
-    ctx.setLineDash([3, 2]);
-    ctx.strokeRect(rx, ry, rw, rh);
-    ctx.setLineDash([]);
-
-    if (el.xAnchor || el.yAnchor) {
-      ctx.font = `${Math.max(7, s)}px sans-serif`;
-      ctx.fillStyle = '#a78bfa';
-      const anchorText = [
-        el.xAnchor ? `x:${el.xAnchor[0]}` : '',
-        el.yAnchor ? `y:${el.yAnchor[0]}` : '',
-      ].filter(Boolean).join(' ');
-      if (anchorText) ctx.fillText(anchorText, rx + 1, ry - 2);
-    }
-
-    // Resize handles: on rect, rounded rect, ellipse
-    if (RESIZABLE_TYPES.includes(el.type)) {
-      const handles = _getRectHandles(el, matrixW, matrixH);
-      const HS = 5;
-      ctx.fillStyle = 'white';
-      ctx.strokeStyle = '#2563eb';
-      ctx.lineWidth = 1;
-      for (const pt of Object.values(handles)) {
-        const hx = pt.x * s - HS / 2;
-        const hy = pt.y * s - HS / 2;
-        ctx.fillRect(hx, hy, HS, HS);
-        ctx.strokeRect(hx, hy, HS, HS);
-      }
-    } else {
-      // Corner dots for non-rectangle elements
-      ctx.fillStyle = '#3b82f6';
-      const HS = 4;
-      for (const [hx, hy] of [
-        [rx - HS / 2, ry - HS / 2], [rx + rw - HS / 2, ry - HS / 2],
-        [rx - HS / 2, ry + rh - HS / 2], [rx + rw - HS / 2, ry + rh - HS / 2],
-      ]) ctx.fillRect(hx, hy, HS, HS);
-    }
-
-    ctx.restore();
-  }
-
-  // ── Dimension tooltip while dragging ─────────────────────────────────
-  function drawDragTooltip(ctx, el, SCALE, matrixW, matrixH) {
-    const bb = getBoundingBox(el, matrixW, matrixH);
-    const label = el.type === 'rectangle'
-      ? `${el.width}×${el.height}`
-      : `${bb.x},${bb.y}`;
-    const s = SCALE;
-    ctx.save();
-    ctx.font = `${Math.max(9, s * 1.5)}px monospace`;
-    const tw = ctx.measureText(label).width;
-    const tx = bb.x * s, ty = (bb.y - 2) * s;
-    ctx.fillStyle = 'rgba(0,0,0,0.7)';
-    ctx.fillRect(tx - 2, ty - 10, tw + 4, 12);
-    ctx.fillStyle = 'white';
-    ctx.fillText(label, tx, ty);
-    ctx.restore();
-  }
-
-  // ── Public API ───────────────────────────────────────────────────────
-
-  function init(canvasEl) {
-    _canvas = canvasEl;
-    _ctx = canvasEl.getContext('2d');
-  }
-
-  function setGrid(show) { _showGrid = show; }
-
-  function updateCanvasSize(matrixW, matrixH, SCALE) {
-    if (!_canvas) return;
-    _canvas.width = matrixW * SCALE;
-    _canvas.height = matrixH * SCALE;
-  }
-
-  function render(elements, selectedId, matrixW, matrixH, SCALE, opts = {}) {
-    if (!_ctx) return;
-    const cW = matrixW * SCALE, cH = matrixH * SCALE;
-
-    const bg = opts.bgColor;
-    _ctx.fillStyle = bg ? `rgb(${bg.r},${bg.g},${bg.b})` : '#000';
-    _ctx.fillRect(0, 0, cW, cH);
-
-    if (_showGrid) {
-      _ctx.strokeStyle = 'rgba(255,255,255,0.07)';
-      _ctx.lineWidth = 0.5;
-      for (let x = SCALE; x < cW; x += SCALE) {
-        _ctx.beginPath(); _ctx.moveTo(x, 0); _ctx.lineTo(x, cH); _ctx.stroke();
-      }
-      for (let y = SCALE; y < cH; y += SCALE) {
-        _ctx.beginPath(); _ctx.moveTo(0, y); _ctx.lineTo(cW, y); _ctx.stroke();
-      }
-    }
-
-    for (const el of elements) _drawElement(_ctx, el, SCALE, matrixW, matrixH, opts);
-
-    if (opts.showRuler) {
-      _ctx.save();
-      _ctx.fillStyle = 'rgba(255,255,255,0.08)';
-      _ctx.fillRect(0, 0, cW, SCALE);             // top strip
-      _ctx.fillRect(0, 0, SCALE, cH);             // left strip
-      _ctx.strokeStyle = 'rgba(255,255,255,0.5)';
-      _ctx.fillStyle = 'rgba(255,255,255,0.6)';
-      _ctx.font = `${Math.max(5, SCALE - 1)}px monospace`;
-      const step = SCALE >= 4 ? 8 : 16;
-      for (let px = 0; px <= matrixW; px += step) {
-        const cx = px * SCALE;
-        const major = px % 32 === 0;
-        _ctx.lineWidth = 0.5;
-        _ctx.beginPath(); _ctx.moveTo(cx, 0); _ctx.lineTo(cx, major ? SCALE : SCALE * 0.5); _ctx.stroke();
-        if (major && px > 0 && px < matrixW - 4) _ctx.fillText(String(px), cx + 1, SCALE - 1);
-      }
-      for (let py = 0; py <= matrixH; py += step) {
-        const cy = py * SCALE;
-        const major = py % 32 === 0;
-        _ctx.beginPath(); _ctx.moveTo(0, cy); _ctx.lineTo(major ? SCALE : SCALE * 0.5, cy); _ctx.stroke();
-        if (major && py > 0 && py < matrixH - 4) _ctx.fillText(String(py), 1, cy + SCALE - 1);
-      }
-      _ctx.restore();
-    }
-
-    if (opts.showGuides) {
-      _ctx.save();
-      _ctx.strokeStyle = 'rgba(255,60,60,0.45)';
-      _ctx.lineWidth = 1;
-      _ctx.setLineDash([4, 3]);
-      const mx = Math.floor(cW / 2) + 0.5;
-      const my = Math.floor(cH / 2) + 0.5;
-      _ctx.beginPath(); _ctx.moveTo(mx, 0); _ctx.lineTo(mx, cH); _ctx.stroke();
-      _ctx.beginPath(); _ctx.moveTo(0, my); _ctx.lineTo(cW, my); _ctx.stroke();
-      _ctx.setLineDash([]);
-      _ctx.restore();
-    }
-
-    const sel = selectedId != null ? elements.find(e => e.id === selectedId) : null;
-    if (sel) {
-      _drawSelection(_ctx, sel, SCALE, matrixW, matrixH);
-      if (opts.showTooltip) drawDragTooltip(_ctx, sel, SCALE, matrixW, matrixH);
-    }
-  }
-
-  return {
-    init, render, setGrid, updateCanvasSize,
-    hitTest, getBoundingBox, computeActualPos, resolveAnchor,
-    getResizeHandle, getCursorForHandle,
-    ELEMENT_DEFAULTS, FONT_MAP, DISPLAY_PRESETS, RESIZABLE_TYPES,
-  };
-})();

web_interface/templates/v3/composer/manager.py.j2

@@ -1,302 +0,0 @@
-"""
-{{ plugin_name }} — LEDMatrix Plugin
-Generated by LEDMatrix Plugin Composer on {{ generated_date }}
-
-Extension points:
-  update()              → add HTTP/MQTT data-fetching logic here
-  _get_display_values() → map fetched data to display strings
-  display()             → add new elements or adapt layout per display size
-"""
-from src.plugin_system.base_plugin import BasePlugin
-{% if has_clock or has_countdown %}
-from datetime import datetime
-{% endif %}
-{% if has_blink %}
-import time
-{% endif %}
-{% if has_text_template %}
-from collections import defaultdict
-{% endif %}
-
-
-class {{ class_name }}(BasePlugin):
-
-    def __init__(self, plugin_id, config, display_manager, cache_manager, plugin_manager):
-        super().__init__(plugin_id, config, display_manager, cache_manager, plugin_manager)
-{% for var in config_vars %}
-        self.{{ var.key }} = config.get({{ var.key | tojson }}, {{ var.default | tojson }})
-{% endfor %}
-        # Live data cache — populated by update(); always {} in static layouts
-        self._data = {}
-
-    def update(self):
-        """Fetch and refresh display data.
-
-        For dynamic plugins: fetch from APIs/MQTT here and store in self._data.
-        _get_display_values() will read self._data to produce display strings.
-        """
-        # --- Data sources (add fetch logic here for dynamic plugins) ---
-        pass
-
-    def _get_display_values(self):
-        """Map config variables and live data to display-ready strings.
-
-        This is the single extension point for v2 data sources:
-        add self._data lookups here once update() populates them.
-        """
-        return {
-{% for var in config_vars %}
-            {{ var.key | tojson }}: str(self.{{ var.key }}),
-{% endfor %}
-        }
-
-    def display(self, force_clear=False):
-        try:
-{% if has_text_template %}
-            values = defaultdict(str, self._get_display_values())
-{% else %}
-            values = self._get_display_values()
-{% endif %}
-
-            if force_clear:
-                self.display_manager.clear()
-
-            width = self.display_manager.width
-            height = self.display_manager.height
-{% if bg_color %}
-
-            self.display_manager.draw.rectangle([0, 0, width, height], fill={{ bg_color }})
-{% endif %}
-
-            # ── Elements (rendered bottom to top) ──────────────────────────
-{% for el in elements %}
-{% set p = "                " if el.min_width > 0 else "            " %}
-{% set pi = (p + "    ") if el.blink else p %}
-{% if el.min_width > 0 %}
-            if width >= {{ el.min_width }}:  # breakpoint: {{ el.min_width }}px+ displays only
-{% endif %}
-{% if el.blink %}
-{{ p }}if int(time.time() * 2) % 2:
-{% endif %}
-
-{% if el.type == 'text' %}
-{{ pi }}self.display_manager.draw_text(
-{% if el.text_is_template %}
-{{ pi }}    {{ el.text | tojson }}.format_map(values),
-{% else %}
-{{ pi }}    {{ el.text | tojson }},
-{% endif %}
-{{ pi }}    x={{ el.x_expr }}, y={{ el.y_expr }},
-{{ pi }}    color={{ el.rgb_tuple }},
-{{ pi }}    font=self.display_manager.{{ el.font_attr }},
-{{ pi }})
-{% if el.text2 %}
-{{ pi }}self.display_manager.draw_text(
-{% if el.text_is_template %}
-{{ pi }}    {{ el.text2 | tojson }}.format_map(values),
-{% else %}
-{{ pi }}    {{ el.text2 | tojson }},
-{% endif %}
-{{ pi }}    x={{ el.x2_expr }}, y={{ el.y2_expr }},
-{{ pi }}    color={{ el.rgb_tuple }},
-{{ pi }}    font=self.display_manager.{{ el.font_attr }},
-{{ pi }})
-{% endif %}
-{% elif el.type == 'dynamic_text' %}
-{% if el.binding_source == 'config' %}
-{{ pi }}self.display_manager.draw_text(
-{{ pi }}    values.get({{ el.binding_key | tojson }}, ''),
-{{ pi }}    x={{ el.x_expr }}, y={{ el.y_expr }},
-{{ pi }}    color={{ el.rgb_tuple }},
-{{ pi }}    font=self.display_manager.{{ el.font_attr }},
-{{ pi }})
-{% else %}
-{{ pi }}pass  # non-config dynamic_text binding draws nothing
-{% endif %}
-{% elif el.type == 'clock' %}
-{{ pi }}self.display_manager.draw_text(
-{{ pi }}    datetime.now().strftime({{ el.format | tojson }}),
-{{ pi }}    x={{ el.x_expr }}, y={{ el.y_expr }},
-{{ pi }}    color={{ el.rgb_tuple }},
-{{ pi }}    font=self.display_manager.{{ el.font_attr }},
-{{ pi }})
-{% if el.format2 %}
-{{ pi }}self.display_manager.draw_text(
-{{ pi }}    datetime.now().strftime({{ el.format2 | tojson }}),
-{{ pi }}    x={{ el.x2_expr }}, y={{ el.y2_expr }},
-{{ pi }}    color={{ el.rgb_tuple }},
-{{ pi }}    font=self.display_manager.{{ el.font_attr }},
-{{ pi }})
-{% endif %}
-{% elif el.type == 'countdown' %}
-{{ pi }}_cd_target = float(values.get({{ el.binding_key | tojson }}, 0) or 0)
-{{ pi }}_cd_secs = max(0.0, _cd_target - datetime.now().timestamp())
-{% if el.countdown_format == 'dhms' %}
-{{ pi }}_cd_d, _cd_rem = divmod(int(_cd_secs), 86400)
-{{ pi }}_cd_h, _cd_rem = divmod(_cd_rem, 3600)
-{{ pi }}_cd_m, _cd_s = divmod(_cd_rem, 60)
-{{ pi }}_cd_str = f'{_cd_d}d {_cd_h:02d}:{_cd_m:02d}:{_cd_s:02d}'
-{% elif el.countdown_format == 'hms' %}
-{{ pi }}_cd_h, _cd_rem = divmod(int(_cd_secs), 3600)
-{{ pi }}_cd_m, _cd_s = divmod(_cd_rem, 60)
-{{ pi }}_cd_str = f'{_cd_h}h {_cd_m:02d}:{_cd_s:02d}'
-{% elif el.countdown_format == 'dhm' %}
-{{ pi }}_cd_d, _cd_rem = divmod(int(_cd_secs), 86400)
-{{ pi }}_cd_h, _cd_m = divmod(_cd_rem // 60, 60)
-{{ pi }}_cd_str = f'{_cd_d}d {_cd_h:02d}h {_cd_m:02d}m'
-{% else %}
-{{ pi }}_cd_d, _cd_rem = divmod(int(_cd_secs), 86400)
-{{ pi }}_cd_h = _cd_rem // 3600
-{{ pi }}_cd_str = f'{_cd_d}d {_cd_h}h'
-{% endif %}
-{{ pi }}self.display_manager.draw_text(
-{{ pi }}    _cd_str,
-{{ pi }}    x={{ el.x_expr }}, y={{ el.y_expr }},
-{{ pi }}    color={{ el.rgb_tuple }},
-{{ pi }}    font=self.display_manager.{{ el.font_attr }},
-{{ pi }})
-{% elif el.type == 'rectangle' %}
-{{ pi }}self.display_manager.draw.rectangle(
-{{ pi }}    [{{ el.x_expr }}, {{ el.y_expr }}, {{ el.x2_expr }}, {{ el.y2_expr }}],
-{{ pi }}    fill={{ el.fill_tuple }},
-{{ pi }}    outline={{ el.outline_tuple }},
-{{ pi }})
-{% elif el.type == 'arc' %}
-{{ pi }}self.display_manager.draw.arc(
-{{ pi }}    [{{ el.x_expr }}, {{ el.y_expr }}, {{ el.x2_expr }}, {{ el.y2_expr }}],
-{{ pi }}    start={{ el.start_angle }}, end={{ el.end_angle }},
-{{ pi }}    fill={{ el.rgb_tuple }},
-{{ pi }}    width={{ el.line_width }},
-{{ pi }})
-{% elif el.type == 'ellipse' %}
-{{ pi }}self.display_manager.draw.ellipse(
-{{ pi }}    [{{ el.x_expr }}, {{ el.y_expr }}, {{ el.x2_expr }}, {{ el.y2_expr }}],
-{{ pi }}    fill={{ el.fill_tuple }},
-{{ pi }}    outline={{ el.outline_tuple }},
-{{ pi }})
-{% elif el.type == 'pixel' %}
-{{ pi }}self.display_manager.draw.point(
-{{ pi }}    [{{ el.x_expr }}, {{ el.y_expr }}],
-{{ pi }}    fill={{ el.rgb_tuple }},
-{{ pi }})
-{% elif el.type == 'rounded_rectangle' %}
-{{ pi }}self.display_manager.draw.rounded_rectangle(
-{{ pi }}    [{{ el.x_expr }}, {{ el.y_expr }}, {{ el.x2_expr }}, {{ el.y2_expr }}],
-{{ pi }}    radius={{ el.border_radius }},
-{{ pi }}    fill={{ el.fill_tuple }},
-{{ pi }}    outline={{ el.outline_tuple }},
-{{ pi }})
-{% elif el.type in ('line', 'divider') %}
-{{ pi }}self.display_manager.draw.line(
-{{ pi }}    [{{ el.x0_expr }}, {{ el.y0_expr }}, {{ el.x1_expr }}, {{ el.y1_expr }}],
-{{ pi }}    fill={{ el.rgb_tuple }},
-{{ pi }}    width={{ el.line_width }},
-{{ pi }})
-{% elif el.type == 'pips' %}
-{{ pi }}_pip_filled = max(0, min({{ el.pip_count }}, int(float(values.get({{ el.binding_key | tojson }}, 0) or 0))))
-{{ pi }}for _pip_i in range({{ el.pip_count }}):
-{{ pi }}    _pip_x = ({{ el.x_expr }}) + _pip_i * ({{ el.pip_size }} + {{ el.pip_spacing }})
-{{ pi }}    _pip_color = {{ el.fill_tuple }} if _pip_i < _pip_filled else {{ el.empty_tuple }}
-{% if not el.show_empty %}
-{{ pi }}    if _pip_i >= _pip_filled:
-{{ pi }}        continue
-{% endif %}
-{{ pi }}    self.display_manager.draw.rectangle(
-{{ pi }}        [_pip_x, {{ el.y_expr }}, _pip_x + {{ el.pip_size }} - 1, ({{ el.y_expr }}) + {{ el.pip_size }} - 1],
-{{ pi }}        fill=_pip_color,
-{{ pi }}    )
-{% elif el.type == 'sparkline' %}
-{{ pi }}_sl_raw = str(values.get({{ el.binding_key | tojson }}, '') or '')
-{{ pi }}_sl_vals = [float(v.strip()) for v in _sl_raw.split(',') if v.strip()][:{{ el.bar_count }}]
-{{ pi }}_sl_vals += [0.0] * max(0, {{ el.bar_count }} - len(_sl_vals))
-{{ pi }}_sl_max = max(_sl_vals) if any(_sl_vals) else 1.0
-{{ pi }}_sl_bw = max(1, ({{ el.bar_width_px }} - {{ el.bar_spacing }} * ({{ el.bar_count }} - 1)) // {{ el.bar_count }})
-{% if el.bg_tuple != 'None' %}
-{{ pi }}self.display_manager.draw.rectangle(
-{{ pi }}    [{{ el.x_expr }}, {{ el.y_expr }}, ({{ el.x_expr }}) + {{ el.bar_width_px }}, ({{ el.y_expr }}) + {{ el.bar_height_px }}],
-{{ pi }}    fill={{ el.bg_tuple }},
-{{ pi }})
-{% endif %}
-{{ pi }}for _sl_i, _sl_v in enumerate(_sl_vals):
-{{ pi }}    _sl_norm = max(0.0, min(1.0, _sl_v / (_sl_max or 1)))
-{{ pi }}    _sl_bh = max(1, round({{ el.bar_height_px }} * _sl_norm))
-{{ pi }}    _sl_bx = ({{ el.x_expr }}) + (_sl_bw + {{ el.bar_spacing }}) * _sl_i
-{{ pi }}    _sl_by = ({{ el.y_expr }}) + {{ el.bar_height_px }} - _sl_bh
-{{ pi }}    self.display_manager.draw.rectangle(
-{{ pi }}        [_sl_bx, _sl_by, _sl_bx + _sl_bw - 1, _sl_by + _sl_bh - 1],
-{{ pi }}        fill={{ el.fill_tuple }},
-{{ pi }}    )
-{% elif el.type == 'gauge' %}
-{{ pi }}_gv = max(0.0, min(100.0, float(values.get({{ el.binding_key | tojson }}, 0) or 0)))
-{{ pi }}_g_total = (({{ el.end_angle }} - {{ el.start_angle }}) % 360) or 360
-{{ pi }}_g_sweep = _g_total * _gv / 100.0
-{% if el.track_tuple != 'None' %}
-{{ pi }}self.display_manager.draw.arc(
-{{ pi }}    [{{ el.x_expr }}, {{ el.y_expr }}, {{ el.x2_expr }}, {{ el.y2_expr }}],
-{{ pi }}    start={{ el.start_angle }}, end={{ el.start_angle }} + _g_total,
-{{ pi }}    fill={{ el.track_tuple }},
-{{ pi }}    width={{ el.line_width }},
-{{ pi }})
-{% endif %}
-{{ pi }}if _g_sweep > 0:
-{{ pi }}    self.display_manager.draw.arc(
-{{ pi }}        [{{ el.x_expr }}, {{ el.y_expr }}, {{ el.x2_expr }}, {{ el.y2_expr }}],
-{{ pi }}        start={{ el.start_angle }}, end={{ el.start_angle }} + _g_sweep,
-{{ pi }}        fill={{ el.rgb_tuple }},
-{{ pi }}        width={{ el.line_width }},
-{{ pi }}    )
-{% if el.show_label %}
-{{ pi }}_g_cx = ({{ el.x_expr }}) + ({{ el.x2_expr }} - ({{ el.x_expr }})) // 2
-{{ pi }}_g_cy = ({{ el.y_expr }}) + ({{ el.y2_expr }} - ({{ el.y_expr }})) // 2
-{{ pi }}self.display_manager.draw_text(
-{{ pi }}    f'{int(_gv)}%',
-{{ pi }}    x=_g_cx, y=_g_cy,
-{{ pi }}    color={{ el.label_tuple }},
-{{ pi }}    font=self.display_manager.{{ el.font_attr }},
-{{ pi }})
-{% endif %}
-{% elif el.type == 'marquee' %}
-{{ pi }}_{{ el.data_key }}_text = {{ el.text | tojson }}
-{{ pi }}_{{ el.data_key }}_tw = len(_{{ el.data_key }}_text) * {{ el.char_w }}
-{{ pi }}_{{ el.data_key }}_x = int(self._data.get({{ el.data_key | tojson }}, width))
-{% if el.direction == 'right' %}
-{{ pi }}_{{ el.data_key }}_x += {{ el.scroll_speed }}
-{{ pi }}if _{{ el.data_key }}_x > width:
-{{ pi }}    _{{ el.data_key }}_x = -(_{{ el.data_key }}_tw + {{ el.gap }})
-{% else %}
-{{ pi }}_{{ el.data_key }}_x -= {{ el.scroll_speed }}
-{{ pi }}if _{{ el.data_key }}_x < -(_{{ el.data_key }}_tw + {{ el.gap }}):
-{{ pi }}    _{{ el.data_key }}_x = width
-{% endif %}
-{{ pi }}self._data[{{ el.data_key | tojson }}] = _{{ el.data_key }}_x
-{{ pi }}self.display_manager.draw_text(
-{{ pi }}    _{{ el.data_key }}_text,
-{{ pi }}    x=_{{ el.data_key }}_x, y={{ el.y_expr }},
-{{ pi }}    color={{ el.rgb_tuple }},
-{{ pi }}    font=self.display_manager.{{ el.font_attr }},
-{{ pi }})
-{% elif el.type == 'progress_bar' %}
-{{ pi }}_pb_x = {{ el.x_expr }}
-{{ pi }}_pb_y = {{ el.y_expr }}
-{{ pi }}_pb_pct = max(0.0, min(100.0, float(values.get({{ el.binding_key | tojson }}, 0) or 0))) / 100.0
-{{ pi }}_pb_fill_w = int({{ el.bar_width }} * _pb_pct)
-{{ pi }}self.display_manager.draw.rectangle(
-{{ pi }}    [_pb_x, _pb_y, _pb_x + {{ el.bar_width }}, _pb_y + {{ el.bar_height }}],
-{{ pi }}    fill={{ el.bg_tuple }},
-{{ pi }}    outline={{ el.outline_tuple }},
-{{ pi }})
-{{ pi }}if _pb_fill_w > 0:
-{{ pi }}    self.display_manager.draw.rectangle(
-{{ pi }}        [_pb_x, _pb_y, _pb_x + _pb_fill_w, _pb_y + {{ el.bar_height }}],
-{{ pi }}        fill={{ el.fill_tuple }},
-{{ pi }}    )
-{% else %}
-{{ pi }}pass  # element type "{{ el.type }}" draws nothing
-{% endif %}
-{% endfor %}
-            # ── End elements ───────────────────────────────────────────────
-
-            self.display_manager.update_display()
-
-        except Exception as e:
-            self.logger.error('Display error: %s', e, exc_info=True)