fix(starlark): the six review findings that were still real

CodeRabbit raised eight on this PR. Two were already fixed by later
commits (the F541 f-string prefixes, and the twenty-four CodeQL
path-injection alerts, now zero open and the last two dismissed as
false positives). These are the rest, each verified against the code as
it stands rather than as it was reviewed.

Manifest writes shared one temp file. `with_suffix('.tmp')` is a fixed
path, and five routes write the manifest while Flask serves requests
concurrently -- two writers opened `manifest.tmp`, interleaved their
json.dump output and both renamed. The rename is atomic; the content it
published was the mixture, which the next read cannot parse. mkstemp in
the destination directory gives each writer its own file.

A failed import stayed cached. Both dynamic importers insert into
sys.modules before exec_module, which they must, but left the
half-initialised module behind on failure -- every later call then took
the cache branch and raised AttributeError on the missing class instead
of retrying, so one transient failure disabled the repository or the
renderer for the life of the process. The keys stay unprefixed: the
plugin's own manager.py does `from pixlet_renderer import
PixletRenderer`, and sharing that key is what keeps one module object.

Config was applied before it was saved. A false from save_config()
answers 500, but the loaded app kept the new values, so GET config
reported settings that were never written and the plugin rendered with
them until a restart silently put the old ones back. Snapshot and
restore on the failure branch, and do not re-render.

The toggle reported success it had not earned. `_update_manifest_safe`
returns False on failure and the result was dropped, and the in-memory
flag was flipped first -- so a failed write left a toggle that reverted
itself on the next restart. Persist first, then update memory.

The toggle also could not find what the list had shown.
`_starlark_virtual_plugins` publishes the raw manifest key, while the
toggle re-slugified it through `_validate_and_sanitize_app_id`
(lowercase, every character outside [a-z0-9_] rewritten): an app stored
as `My-App` was offered as `starlark:My-App` and looked up as `my_app`,
so toggling an app the page had just drawn answered 404. Check for
traversal with `_validate_starlark_app_path` and keep the key.

`star_file` was stored absolute. Readers join it to the app's own
directory and default to a bare `<app_id>.star`, so the key had two
meanings -- and `Path.__truediv__` discards the left side when the right
is absolute, pinning the manifest to whatever PROJECT_ROOT installed it.
Store the filename.

Two store tests reached GitHub. browse and categories call
list_all_apps_cached(), which fetches the app index on a cold cache --
slow, network-dependent, rate-limitable, and since both only assert "not
a 404" a rate-limited 500 passed and hid it. The file now runs in 1.5s
rather than 17.5s.

13 new tests, all six findings covered. Whole suite: no new failures
against this branch, 3892 passed against 3879.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

scripts/render_plugin.py

@@ -52,6 +52,10 @@ def main() -> int:
     parser.add_argument('--height', type=int, default=32, help='Display height (default: 32)')
     parser.add_argument('--skip-update', action='store_true',
                         help='Skip calling update() (render display only)')
+    parser.add_argument('--display-mode', default=None,
+                        help='Display mode to render, for plugins that declare '
+                             'more than one in their manifest (e.g. nrl_live). '
+                             'Omitted, the plugin picks its own default.')
 
     args = parser.parse_args()
 
@@ -141,8 +145,26 @@ def main() -> int:
         except Exception as e:
             logger.warning("update() raised: %s — continuing to display()", e)
 
+    # A plugin that declares several display modes usually renders nothing
+    # useful without being told which one to draw: the scoreboards keep their
+    # state on per-mode sub-managers and their no-argument path returns False.
+    # Only pass the argument when asked for, so the many plugins whose display()
+    # takes no display_mode keep working untouched.
     try:
-        plugin_instance.display(force_clear=True)
+        if args.display_mode:
+            try:
+                plugin_instance.display(display_mode=args.display_mode,
+                                        force_clear=True)
+            except TypeError as error:
+                if ("unexpected keyword argument" not in str(error)
+                        or "display_mode" not in str(error)):
+                    raise
+                logger.warning(
+                    "%s.display() does not accept display_mode; rendering its "
+                    "default screen instead", args.plugin)
+                plugin_instance.display(force_clear=True)
+        else:
+            plugin_instance.display(force_clear=True)
         logger.debug("display() completed")
     except Exception as e:
         logger.error("Error in display(): %s", e)

src/common/sports_card.py

@@ -17,10 +17,13 @@ deliberate difference is `crisp_size`, which takes the seven-plugin guard
 the extra guard only stops a None size raising TypeError.
 """
 
+import logging
 from datetime import datetime, timezone
 from typing import Any, Dict, Optional, Tuple
 from zoneinfo import ZoneInfo
 
+logger = logging.getLogger(__name__)
+
 __all__ = [
     "ELEMENT_FOR_FONT", "FAVORITE_RESULT_COLOR_DEFAULTS", "FONT_NAME_ALIASES",
     "FONT_PIXEL_GRID", "MONTH_ABBR", "WEEKDAY_ABBR",
@@ -395,7 +398,14 @@ def schema_font_size(schema_path: str, element_key) -> Optional[int]:
                 size = spec.get('properties', {}).get('font_size', {}).get('default')
                 if size is not None:
                     cache[key] = int(size)
-        except Exception:
+        except Exception as exc:
+            # See sports_shared._schema_font_size: an unreadable schema
+            # silently disables the pixel-grid snap for every element.
+            # Built once per schema path, so this cannot repeat per frame.
+            logger.warning(
+                "could not read %s (%s: %s); font sizes will skip their "
+                "pixel grid snap and may render a pixel narrow",
+                schema_path, type(exc).__name__, exc)
             cache = {}
         _SCHEMA_FONT_SIZE_CACHE[schema_path] = cache
     return cache.get(element_key)

src/common/sports_shared.py

@@ -211,17 +211,52 @@ class SportsCoreSharedMixin:
             return desired
         return max(grid, int(round(float(desired) / grid)) * grid)
 
+    #: Absolute path of this plugin's directory, declared by the plugin
+    #: itself. The mixin cannot work it out -- see _plugin_dir.
+    _PLUGIN_DIR: ClassVar[Optional[str]] = None
+
     def _plugin_dir(self) -> Optional[str]:
-        """Directory of the plugin that defines this class.
+        """Directory of the plugin that owns this instance.
 
         In sports.py these methods could just use ``__file__``. Here that is
-        src/common/, so the plugin's own directory has to be recovered from the
-        instance. ``type(self).__module__`` alone is not enough: SportsCore is
-        an ABC, so a subclass built with ``type(name, bases, ns)`` -- which the
-        plugins' own tests do -- reports its module as "abc". Walking the MRO
-        steps past those synthetic classes to the first one whose module sits
-        next to a config_schema.json, which is the real plugin.
+        src/common/, so the directory has to come from the plugin.
+
+        It is TOLD, not deduced. The first version walked the MRO for a class
+        whose module sits beside a config_schema.json. That works when a test
+        imports the plugin itself, and returns None under the real loader, for
+        a specific reason worth recording:
+
+            PluginLoader._namespace_plugin_modules renames every bare module a
+            plugin brought in (sports, game_renderer, ...) to
+            "_plg_<plugin_id>_<module>" and REMOVES the bare entry, so two
+            plugins owning a module of the same name cannot collide.
+
+        The class still reports ``__module__ == "sports"``, but
+        ``sys.modules["sports"]`` no longer exists, so the walk finds no
+        __file__ and falls off the end. The failure was silent and expensive:
+
+            _plugin_dir()       -> None
+            _schema_font_size() -> None for every element
+            -> a configured size equal to the schema default stops looking
+               like a default and is treated as a deliberate user choice
+            -> the snap to the font's pixel grid is skipped
+            -> 4x6-font.ttf renders at 6 instead of 7: 3px-wide glyphs
+               instead of 4px
+
+        On a 256x64 panel that made the odds, the team records and the date row
+        hard to read. It was found by a user counting pixels on the panel. No
+        gate here caught it: the tests imported plugins directly and the
+        safety harness loads them its own way, so neither reproduced the
+        loader's renaming.
+
+        The MRO walk stays as a fallback for hosts that declare no
+        _PLUGIN_DIR -- the plugins' own probe harnesses build classes with
+        ``type()`` -- but it is no longer the primary answer.
         """
+        declared = getattr(self, "_PLUGIN_DIR", None)
+        if declared and os.path.isfile(os.path.join(declared, "config_schema.json")):
+            return declared
+
         for cls in type(self).__mro__:
             module = sys.modules.get(getattr(cls, "__module__", ""), None)
             path = getattr(module, "__file__", None)
@@ -253,7 +288,23 @@ class SportsCoreSharedMixin:
                     size = spec.get('properties', {}).get('font_size', {}).get('default')
                     if size is not None:
                         cache[key] = int(size)
-            except Exception:
+            except Exception as exc:
+                # Say so. An unreadable schema is not cosmetic: every element's
+                # configured size then stops matching "the schema default", is
+                # treated as a deliberate user choice, and skips the snap to the
+                # font's pixel grid -- which renders 4x6-font.ttf at 6 instead
+                # of 7, a 3px-wide glyph instead of 4px. That shipped once,
+                # silently, and was found by a user counting pixels on a photo
+                # of the panel.
+                #
+                # Logged, not raised: a missing schema must not stop a plugin
+                # rendering. The cache is built once per class, so this cannot
+                # repeat per frame.
+                logger.warning(
+                    "%s: could not read config_schema.json (%s: %s); every font "
+                    "size will be treated as user-chosen and will skip its pixel "
+                    "grid snap. Font sizes may render a pixel narrow.",
+                    type(self).__name__, type(exc).__name__, exc)
                 cache = {}
             self.__class__._SCHEMA_FONT_SIZES = cache
         return cache.get(element_key)

src/display_manager.py

@@ -364,6 +364,7 @@ class DisplayManager:
             # Create image with the (logical) display dimensions
             self.image = Image.new('RGB', (self.matrix.width, self.matrix.height))
             self.draw = ImageDraw.Draw(self.image)
+            self.draw.fontmode = "1"  # 1-bit text: the panel has no partial brightness, so AA only smears glyphs.
             logger.info(f"Image canvas created with dimensions: {self.matrix.width}x{self.matrix.height}")
             
             # Initialize font with Press Start 2P
@@ -403,6 +404,7 @@ class DisplayManager:
 
             self.image = Image.new('RGB', (fallback_width, fallback_height))
             self.draw = ImageDraw.Draw(self.image)
+            self.draw.fontmode = "1"  # 1-bit text: the panel has no partial brightness, so AA only smears glyphs.
             # Simple fallback visualization so web UI shows a realistic canvas
             try:
                 self.draw.rectangle([0, 0, fallback_width - 1, fallback_height - 1], outline=(255, 0, 0))
@@ -705,6 +707,7 @@ class DisplayManager:
             # self.image, so swapping the buffer below is enough on its own.
             self.image = Image.new('RGB', (target_w, target_h))
             self.draw = ImageDraw.Draw(self.image)
+            self.draw.fontmode = "1"  # 1-bit text: the panel has no partial brightness, so AA only smears glyphs.
             yield
         finally:
             self.matrix = real_matrix
@@ -814,6 +817,7 @@ class DisplayManager:
                 
                 self.image = Image.new('RGB', (width, height))
                 self.draw = ImageDraw.Draw(self.image)
+                self.draw.fontmode = "1"  # 1-bit text: the panel has no partial brightness, so AA only smears glyphs.
                 logger.debug("Cleared display in fallback mode")
                 return
                 
@@ -825,6 +829,7 @@ class DisplayManager:
             # Create a new black image
             self.image = Image.new('RGB', (self.matrix.width, self.matrix.height))
             self.draw = ImageDraw.Draw(self.image)
+            self.draw.fontmode = "1"  # 1-bit text: the panel has no partial brightness, so AA only smears glyphs.
 
             if not self._capture_mode_active:
                 # Clear both canvases and the underlying matrix to ensure no artifacts.
@@ -1258,6 +1263,7 @@ class DisplayManager:
             try:
                 self.image = Image.new('RGB', (self.width, self.height))
                 self.draw = ImageDraw.Draw(self.image)
+                self.draw.fontmode = "1"  # 1-bit text: the panel has no partial brightness, so AA only smears glyphs.
             except (OSError, RuntimeError, ValueError, MemoryError):
                 logger.debug("Canvas reset during cleanup failed", exc_info=True)
         # Reset the singleton state when cleaning up

src/plugin_system/compatibility.py

@@ -28,6 +28,7 @@ fixes their version string. See `docs/SPORTS_UNIFICATION.md`, phase B4.
 from __future__ import annotations
 
 import re
+from pathlib import Path
 from typing import Any, Dict, Optional, Tuple
 
 # Below this, the core's self-reported version is not evidence of anything.
@@ -35,6 +36,45 @@ from typing import Any, Dict, Optional, Tuple
 TRUSTWORTHY_FLOOR: Tuple[int, int, int] = (2, 0, 0)
 
 
+# ``src/__init__.py`` relative to this file: src/plugin_system/ -> src/
+_VERSION_FILE = Path(__file__).resolve().parent.parent / "__init__.py"
+_VERSION_RE = re.compile(r'^__version__\s*=\s*["\']([^"\']+)["\']', re.M)
+
+
+def current_core_version() -> str:
+    """The core version as it is on disk right now, not as it was at import.
+
+    ``from src import __version__`` binds whatever the process loaded at start.
+    The web UI runs as its own long-lived service (``ledmatrix-web.service``),
+    and updating the core replaces files on disk without restarting it -- the
+    update route says so explicitly and asks the user to restart. Its prompt
+    names the *display* service, so a user who follows it leaves the web
+    process holding the old number.
+
+    The plugin store's gate lives in that web process. Stale by one release is
+    exactly the case that matters: every plugin flooring on the release you
+    just installed gets refused, with a message blaming a core version that is
+    already correct on disk. 3.3.0 is the first release where that hits a whole
+    plugin family at once -- all eight sports scoreboards floor there.
+
+    Reading the file costs one stat and a small read per call, and only on the
+    install/update path. Any failure falls back to the imported value, so this
+    can only ever be as wrong as before, never worse.
+    """
+    try:
+        text = _VERSION_FILE.read_text(encoding="utf-8")
+        match = _VERSION_RE.search(text)
+        if match:
+            return match.group(1)
+    except (OSError, UnicodeDecodeError):
+        pass
+    try:
+        from src import __version__ as imported
+        return imported
+    except Exception:            # noqa: BLE001 - never let this raise
+        return "0.0.0"
+
+
 def parse_semver(value: Any) -> Optional[Tuple[int, int, int]]:
     """Parse ``X.Y.Z`` (extra parts and suffixes ignored) into a comparable
     3-tuple, or ``None`` when unparseable. A leading ``v`` is tolerated."""

src/plugin_system/plugin_loader.py

@@ -772,8 +772,8 @@ class PluginLoader:
         newer than the running core. Advisory only — never raises — so a
         plugin that guards optional features with try/except keeps working.
         """
-        from src import __version__ as core_version
         from src.plugin_system import compatibility
+        core_version = compatibility.current_core_version()
 
         compatible, _reason = compatibility.check(manifest, core_version)
         if compatible:

src/plugin_system/store_manager.py

@@ -1467,8 +1467,11 @@ class PluginStoreManager:
                 # already had. Allowing it costs them a plugin that raises
                 # ModuleNotFoundError at load and is reported only as one line
                 # in the journal. See docs/SPORTS_UNIFICATION.md (phase B4/B6).
-                from src import __version__ as core_version
                 from src.plugin_system import compatibility
+                # On disk, not as imported: this process may predate the core
+                # update that made the plugin compatible. See
+                # compatibility.current_core_version.
+                core_version = compatibility.current_core_version()
 
                 compatible, reason = compatibility.check(manifest, core_version)
                 if not compatible:
@@ -1612,8 +1615,8 @@ class PluginStoreManager:
             #
             # Before the move, so the `finally` below removes the temp tree and
             # nothing half-installed is left behind.
-            from src import __version__ as core_version
             from src.plugin_system import compatibility
+            core_version = compatibility.current_core_version()
 
             compatible, reason = compatibility.check(manifest, core_version)
             if not compatible:
@@ -2644,8 +2647,8 @@ class PluginStoreManager:
                 manifest_path, plugin_id, e)
             return True
 
-        from src import __version__ as core_version
         from src.plugin_system import compatibility
+        core_version = compatibility.current_core_version()
 
         compatible, reason = compatibility.check(manifest, core_version)
         if compatible:

src/plugin_system/testing/visual_display_manager.py

@@ -70,6 +70,7 @@ class VisualTestDisplayManager:
         # Canvas
         self.image = Image.new('RGB', (width, height), (0, 0, 0))
         self.draw = ImageDraw.Draw(self.image)
+        self.draw.fontmode = "1"  # Match production: 1-bit text, so goldens show what the panel shows.
 
         # Matrix proxy (plugins access display_manager.matrix.width/height)
         self.matrix = _MatrixProxy(width, height)
@@ -184,6 +185,7 @@ class VisualTestDisplayManager:
         self.clear_called = True
         self.image = Image.new('RGB', (self._width, self._height), (0, 0, 0))
         self.draw = ImageDraw.Draw(self.image)
+        self.draw.fontmode = "1"  # Match production: 1-bit text, so goldens show what the panel shows.
 
     def update_display(self):
         """No-op for hardware; marks that display was updated."""
@@ -211,6 +213,7 @@ class VisualTestDisplayManager:
             self.matrix = _MatrixProxy(target_w, target_h)
             self.image = Image.new('RGB', (target_w, target_h), (0, 0, 0))
             self.draw = ImageDraw.Draw(self.image)
+            self.draw.fontmode = "1"  # Match production: 1-bit text, so goldens show what the panel shows.
             yield
         finally:
             self._width, self._height = prev_w, prev_h
@@ -569,6 +572,7 @@ class VisualTestDisplayManager:
         self.draw_calls = []
         self.image = Image.new('RGB', (self._width, self._height), (0, 0, 0))
         self.draw = ImageDraw.Draw(self.image)
+        self.draw.fontmode = "1"  # Match production: 1-bit text, so goldens show what the panel shows.
         self._scrolling_state = {
             'is_scrolling': False,
             'last_scroll_activity': 0,
@@ -582,3 +586,4 @@ class VisualTestDisplayManager:
         """Clean up resources."""
         self.image = Image.new('RGB', (self._width, self._height), (0, 0, 0))
         self.draw = ImageDraw.Draw(self.image)
+        self.draw.fontmode = "1"  # Match production: 1-bit text, so goldens show what the panel shows.

test/test_core_version_freshness.py

@@ -0,0 +1,122 @@
+"""The gate must read the core version from disk, not from its own import.
+
+`from src import __version__` binds whatever the process loaded at start. The
+web UI is a long-lived service of its own (ledmatrix-web.service), and updating
+the core replaces files on disk without restarting it -- the update route says
+so and asks the user to restart, but its prompt named only the *display*
+service, so a user who followed it left the web process holding the old number.
+
+The plugin store's gate lives in that web process, so being stale by exactly
+one release is the case that bites: every plugin flooring on the release you
+just installed is refused, with a message blaming a core version that is
+already correct on disk.
+
+Observed on hardware: after updating a rig to 3.3.0 and restarting only the
+display service, all eight sports scoreboards were refused with
+"supports LEDMatrix >=3.3.0, but this system is running 3.2.0" while
+src/__init__.py on that machine read 3.3.0.
+"""
+
+import importlib
+import sys
+
+import pytest
+
+from src.plugin_system import compatibility
+
+
+class TestCurrentCoreVersion:
+    def test_it_reads_the_file_rather_than_the_imported_value(self, monkeypatch, tmp_path):
+        # Simulate a process whose import predates the update: the module
+        # object says 3.2.0 while the file on disk says 3.3.0.
+        import src
+        monkeypatch.setattr(src, "__version__", "3.2.0")
+        fake = tmp_path / "__init__.py"
+        fake.write_text('__version__ = "3.3.0"\n', encoding="utf-8")
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", fake)
+        assert compatibility.current_core_version() == "3.3.0"
+
+    def test_it_matches_the_real_file_by_default(self):
+        import src
+        assert compatibility.current_core_version() == src.__version__
+
+    @pytest.mark.parametrize("body", [
+        "__version__ = '3.4.1'\n",
+        '__version__="3.4.1"\n',
+        '"""doc"""\n\n__version__ = "3.4.1"  # trailing comment\n',
+    ])
+    def test_it_tolerates_the_ways_that_line_gets_written(self, monkeypatch, tmp_path, body):
+        fake = tmp_path / "__init__.py"
+        fake.write_text(body, encoding="utf-8")
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", fake)
+        assert compatibility.current_core_version() == "3.4.1"
+
+    def test_a_missing_file_falls_back_to_the_import(self, monkeypatch, tmp_path):
+        # Never worse than before: an unreadable file returns what the old
+        # code would have returned.
+        import src
+        monkeypatch.setattr(src, "__version__", "3.2.0")
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", tmp_path / "gone.py")
+        assert compatibility.current_core_version() == "3.2.0"
+
+    def test_a_file_without_the_line_falls_back(self, monkeypatch, tmp_path):
+        import src
+        monkeypatch.setattr(src, "__version__", "3.2.0")
+        fake = tmp_path / "__init__.py"
+        fake.write_text("# no version here\n", encoding="utf-8")
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", fake)
+        assert compatibility.current_core_version() == "3.2.0"
+
+    def test_it_never_raises(self, monkeypatch, tmp_path):
+        # This runs on the install path; an exception here would surface as a
+        # failed update rather than a version mismatch.
+        bad = tmp_path / "__init__.py"
+        bad.write_bytes(b"\xff\xfe\x00 not utf-8 \xff")
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", bad)
+        assert isinstance(compatibility.current_core_version(), str)
+
+
+class TestTheBugItFixes:
+    def test_a_stale_import_no_longer_refuses_a_compatible_plugin(self, monkeypatch, tmp_path):
+        """The exact hardware failure, as a test."""
+        import src
+        monkeypatch.setattr(src, "__version__", "3.2.0")     # what the process holds
+        fake = tmp_path / "__init__.py"
+        fake.write_text('__version__ = "3.3.0"\n', encoding="utf-8")   # what is on disk
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", fake)
+
+        manifest = {"name": "Hockey Scoreboard", "min_ledmatrix_version": "3.3.0"}
+
+        stale_ok, _ = compatibility.check(manifest, src.__version__)
+        assert stale_ok is False, "precondition: the stale value is what refused it"
+
+        fresh_ok, reason = compatibility.check(
+            manifest, compatibility.current_core_version())
+        assert fresh_ok is True, f"the disk version must allow it, got: {reason}"
+
+    def test_it_still_refuses_when_the_core_really_is_too_old(self, monkeypatch, tmp_path):
+        # The gate must not become permissive: a genuinely old core still says no.
+        fake = tmp_path / "__init__.py"
+        fake.write_text('__version__ = "3.2.0"\n', encoding="utf-8")
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", fake)
+        ok, reason = compatibility.check(
+            {"name": "Hockey", "min_ledmatrix_version": "3.3.0"},
+            compatibility.current_core_version())
+        assert ok is False
+        assert "3.2.0" in (reason or "")
+
+
+class TestCallSites:
+    @pytest.mark.parametrize("module", [
+        "src.plugin_system.store_manager",
+        "src.plugin_system.plugin_loader",
+    ])
+    def test_no_gate_binds_the_version_at_import(self, module):
+        """Catch a future call site reintroducing the stale read."""
+        import inspect
+        mod = importlib.import_module(module)
+        source = inspect.getsource(mod)
+        assert "from src import __version__ as core_version" not in source, (
+            f"{module} binds __version__ at import; use "
+            f"compatibility.current_core_version() so a long-lived process "
+            f"sees a core update.")

test/test_sports_shared.py

@@ -319,3 +319,58 @@ class TestLiveMixin:
         assert not hasattr(h, "_empty_live_streak")
         h._note_live_fetch(False)
         assert h._empty_live_streak == 1
+
+
+class TestPluginDirIsToldNotDeduced:
+    """The regression that shipped: _plugin_dir returned None in production.
+
+    The first version walked the MRO for a class whose module sits beside a
+    config_schema.json. That passes when a test imports the plugin directly --
+    which is how it was verified -- and returns None under the real plugin
+    loader, which imports modules by a path that leaves no such entry on the
+    MRO.
+
+    Silent, and expensive: no schema means _schema_font_size returns None for
+    every element, so a configured size equal to the schema default stops
+    looking like a default, is treated as a deliberate choice, and skips the
+    grid snap. 4x6-font.ttf then renders at 6 rather than 7 -- 3px-wide glyphs
+    instead of 4px. On a 256x64 panel that made the odds, the records and the
+    date row illegible. A user counted the pixels; no gate here caught it.
+    """
+
+    def test_a_declared_directory_is_used(self, tmp_path):
+        d = _write_plugin(tmp_path, "declared")
+        host = type("H", (SportsCoreSharedMixin,), {"_PLUGIN_DIR": str(d)})()
+        assert host._plugin_dir() == str(d)
+
+    def test_it_works_when_no_module_on_the_mro_helps(self, tmp_path, monkeypatch):
+        """The production case: nothing on the MRO sits beside a schema."""
+        d = _write_plugin(tmp_path, "loaderstyle")
+        # A class whose module is not importable by name, as the loader produces.
+        cls = type("Loaded", (SportsCoreSharedMixin,), {"_PLUGIN_DIR": str(d)})
+        cls.__module__ = "a.module.name.that.is.not.in.sys.modules"
+        assert cls.__new__(cls)._plugin_dir() == str(d), (
+            "the declared directory must win when the MRO walk cannot help")
+
+    def test_without_it_the_mro_walk_would_have_failed(self):
+        # Pin the precondition, so this test still means something if the
+        # fallback is ever changed.
+        cls = type("Orphan", (SportsCoreSharedMixin,), {})
+        cls.__module__ = "not.a.real.module"
+        assert cls.__new__(cls)._plugin_dir() is None
+
+    def test_a_declared_directory_without_a_schema_is_not_trusted(self, tmp_path):
+        # A stale or wrong path must not shadow the fallback.
+        empty = tmp_path / "noschema"
+        empty.mkdir()
+        d = _write_plugin(tmp_path, "realone")
+        monkey = type("H", (SportsCoreSharedMixin,), {"_PLUGIN_DIR": str(empty)})
+        assert monkey.__new__(monkey)._plugin_dir() != str(empty)
+
+    def test_the_font_size_consequence(self, tmp_path):
+        """End to end: a declared directory restores the schema lookup."""
+        d = _write_plugin(tmp_path, "sizeconseq")
+        host = type("H", (SportsCoreSharedMixin,), {"_PLUGIN_DIR": str(d)})()
+        assert host._schema_font_size("score") == 16, (
+            "without the schema this is None, which is what made a configured "
+            "size look user-chosen and skipped the grid snap")

test/web_interface/test_starlark_pixlet_routes.py

@@ -0,0 +1,507 @@
+"""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
+import sys
+import tempfile
+import threading
+import types
+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
+
+
+@pytest.fixture
+def offline_repository():
+    """Stand in for TronbyteRepository so the store routes stay offline.
+
+    The browse and categories routes call list_all_apps_cached(), which on a
+    cold server-side cache fetches the app index from GitHub. That would make
+    the suite slow, network-dependent and rate-limitable -- and because these
+    tests only assert "not a 404", a rate-limited 500 would pass and hide it.
+    """
+    repo = MagicMock()
+    repo.list_all_apps_cached.return_value = {
+        'apps': [], 'categories': [], 'authors': [], 'count': 0, 'cached': True,
+    }
+    with patch('web_interface.blueprints.api_v3._get_tronbyte_repository_class',
+               return_value=lambda *a, **kw: repo):
+        yield repo
+
+
+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.
+    """
+
+    def test_browse_does_not_404(self, client, offline_repository):
+        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_categories_does_not_404(self, client, offline_repository):
+        resp = client.get('/api/v3/starlark/repository/categories')
+        assert resp.status_code != 404
+        assert resp.get_json().get('message') != 'Resource not found'
+
+    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 the one _starlark_virtual_plugins publishes.
+
+        It used to be re-slugified on the way in -- lowercased, with every
+        character outside [a-z0-9_] replaced -- so 'My-App' was listed as
+        'starlark:My-App' and looked up as 'my_app', and 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_failed_manifest_write_is_not_reported_as_success(self, client):
+        """The toggle answered 200 while the change was never persisted."""
+        manifest = {'apps': {'demo': {'name': 'Demo', '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=False):
+            resp = client.post('/api/v3/plugins/toggle',
+                               json={'plugin_id': 'starlark:demo', 'enabled': True})
+        assert resp.status_code == 500
+
+    def test_a_loaded_app_is_not_flipped_when_the_manifest_write_fails(self, client):
+        """Persist first, then update memory -- otherwise the UI shows a
+        toggle that silently reverts on the next restart."""
+        app = MagicMock()
+        app.manifest = {'enabled': False}
+        plugin = MagicMock()
+        plugin.apps = {'demo': app}
+        plugin._update_manifest_safe.return_value = False
+
+        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 == 500
+        assert app.manifest['enabled'] is False, "in-memory state changed without being saved"
+
+
+class TestTheManifestSurvivesConcurrentWriters:
+    """Flask serves requests concurrently and five routes write this file.
+
+    The atomic-write pattern used one fixed temp name, `manifest.tmp`, shared
+    by every writer: two of them opened it, interleaved their json.dump output,
+    and both renamed. The rename is atomic; the content it published was the
+    mixture, which the next read could not parse.
+    """
+
+    @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 test_each_writer_gets_its_own_temp_file(self, starlark_dir):
+        from web_interface.blueprints import api_v3 as module
+
+        seen = []
+        real_mkstemp = tempfile.mkstemp
+
+        def recording_mkstemp(*args, **kwargs):
+            fd, name = real_mkstemp(*args, **kwargs)
+            seen.append(name)
+            return fd, name
+
+        with patch.object(module.tempfile, 'mkstemp', side_effect=recording_mkstemp):
+            for i in range(5):
+                assert module._write_starlark_manifest({'apps': {f'app{i}': {}}})
+
+        assert len(set(seen)) == 5, f"writers shared a temp file: {seen}"
+
+    def test_concurrent_writes_leave_readable_json(self, starlark_dir):
+        from web_interface.blueprints import api_v3 as module
+
+        manifests = [{'apps': {f'app{i}': {'name': 'x' * 400}}} for i in range(8)]
+        errors = []
+
+        def write(m):
+            try:
+                module._write_starlark_manifest(m)
+            except Exception as exc:  # noqa: BLE001 - surfaced by the assert below
+                errors.append(exc)
+
+        threads = [threading.Thread(target=write, args=(m,)) for m in manifests]
+        for t in threads:
+            t.start()
+        for t in threads:
+            t.join()
+
+        assert not errors
+        loaded = json.loads((starlark_dir / 'manifest.json').read_text())
+        assert loaded in manifests, "the published manifest was a mix of two writers"
+
+    def test_no_temp_files_are_left_behind(self, starlark_dir):
+        from web_interface.blueprints import api_v3 as module
+        module._write_starlark_manifest({'apps': {}})
+        assert list(starlark_dir.glob('*.tmp')) == []
+
+    def test_the_installed_star_file_is_recorded_by_name(self, starlark_dir, tmp_path):
+        """Readers join this to the app's own directory and default to a bare
+        '<app_id>.star'. An absolute value gave the key two meanings and, since
+        Path.__truediv__ discards the left side when the right is absolute,
+        pinned the manifest to the PROJECT_ROOT it was installed under."""
+        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'})
+
+        entry = json.loads((starlark_dir / 'manifest.json').read_text())['apps']['demo']
+        assert entry['star_file'] == 'demo.star'
+        assert not os.path.isabs(entry['star_file'])
+
+
+class TestATransientImportFailureIsNotPermanent:
+    """Both importers insert into sys.modules before executing the module.
+
+    That order is required -- a module has to be findable while it runs -- but
+    a failure left the half-initialised object cached, so every later call took
+    the cache branch and raised AttributeError on the missing class instead of
+    retrying. One transient failure disabled the repository or the renderer for
+    the life of the process.
+    """
+
+    @pytest.mark.parametrize("getter,key", [
+        ('_get_tronbyte_repository_class', 'tronbyte_repository'),
+        ('_get_pixlet_renderer_class', 'pixlet_renderer'),
+    ])
+    def test_a_failed_import_leaves_no_entry_behind(self, getter, key):
+        from web_interface.blueprints import api_v3 as module
+
+        original = sys.modules.pop(key, None)
+        try:
+            with patch('importlib.util.module_from_spec') as from_spec:
+                from_spec.return_value = types.ModuleType(key)
+                with patch('importlib.util.spec_from_file_location') as spec_from:
+                    spec = MagicMock()
+                    spec.loader.exec_module.side_effect = RuntimeError("network down")
+                    spec_from.return_value = spec
+
+                    with pytest.raises(RuntimeError):
+                        getattr(module, getter)()
+
+            assert key not in sys.modules, "a half-initialised module stayed cached"
+        finally:
+            if original is not None:
+                sys.modules[key] = original
+            else:
+                sys.modules.pop(key, None)
+
+
+class TestConfigIsNotAppliedUntilItIsSaved:
+    """save_config() returning False answers 500, but the loaded app kept the
+    new values -- so GET config reported settings that were never written and
+    the plugin rendered with them until a restart silently reverted them."""
+
+    def _plugin_with_app(self, save_ok):
+        app = MagicMock()
+        app.config = {'city': 'Philadelphia'}
+        app.manifest = {'render_interval': 300, 'display_duration': 15}
+        app.save_config.return_value = save_ok
+        plugin = MagicMock()
+        plugin.apps = {'demo': app}
+        plugin._update_manifest_safe.return_value = True
+        return plugin, app
+
+    def test_a_failed_save_leaves_the_config_untouched(self, client):
+        plugin, app = self._plugin_with_app(save_ok=False)
+        with patch('web_interface.blueprints.api_v3._get_starlark_plugin', return_value=plugin):
+            resp = client.put('/api/v3/starlark/apps/demo/config',
+                              json={'city': 'Pittsburgh'})
+        assert resp.status_code == 500
+        assert app.config == {'city': 'Philadelphia'}
+
+    def test_a_failed_save_leaves_the_timing_untouched(self, client):
+        plugin, app = self._plugin_with_app(save_ok=False)
+        with patch('web_interface.blueprints.api_v3._get_starlark_plugin', return_value=plugin):
+            resp = client.put('/api/v3/starlark/apps/demo/config',
+                              json={'render_interval': 60})
+        assert resp.status_code == 500
+        assert app.manifest['render_interval'] == 300
+
+    def test_a_failed_save_does_not_re_render_with_values_it_did_not_keep(self, client):
+        plugin, _ = self._plugin_with_app(save_ok=False)
+        with patch('web_interface.blueprints.api_v3._get_starlark_plugin', return_value=plugin):
+            client.put('/api/v3/starlark/apps/demo/config', json={'city': 'Pittsburgh'})
+        plugin._render_app.assert_not_called()
+
+    def test_a_successful_save_still_applies(self, client):
+        plugin, app = self._plugin_with_app(save_ok=True)
+        with patch('web_interface.blueprints.api_v3._get_starlark_plugin', return_value=plugin):
+            resp = client.put('/api/v3/starlark/apps/demo/config',
+                              json={'city': 'Pittsburgh', 'render_interval': 60})
+        assert resp.status_code == 200
+        assert app.config['city'] == 'Pittsburgh'
+        assert app.manifest['render_interval'] == 60
+        plugin._render_app.assert_called_once()

web_interface/templates/v3/base.html

@@ -1164,9 +1164,16 @@
                 // The pull replaced files on disk; the running services still
                 // hold the code they loaded at boot. Ask for the restart that
                 // makes the update actually take effect.
+                //
+                // Both services, not just the display. The plugin store's
+                // compatibility gate runs in the web process, so a web service
+                // still holding the previous version refuses every plugin that
+                // floors on the release just installed -- blaming a core
+                // version that is already correct on disk.
                 if (data.restart_required && typeof window.showRestartPending === 'function') {
                     window.showRestartPending(
-                        'Update installed \u2014 restart the display to run the new code');
+                        'Update installed \u2014 restart the display and web ' +
+                        'services to run the new code');
                 }
             }
             if (typeof showNotification === 'function') {