feat(dev): preview a plugin's Vegas strip in the dev server (#700)

* perf(timing): say which render-thread work a late frame followed

The soak already says how often a moving frame reached the panel late, but
not what the render thread was doing just before it. Vegas does two kinds of
work there between frames -- building its strip (compose, extend) and, with
live elements, patching changed pixels into it -- and deciding whether either
is affordable needs their own numbers.

- FrameTimingRecorder.note_op(kind, nbytes) tags the next presented frame.
  Totals gain op_frames, late_op_frames, op_freezes and op_bytes per kind;
  aggregate() still takes frames without ops. The file schema is unchanged.
- Vegas tags compose and every strip extension (with the bytes it copied).
- frame_soak prints an "after work" table: frames, late %, freezes and MB
  moved per kind, only when something tagged its work.
- render_bench gains --strip-screens (Vegas-sized strips), --patch-bytes /
  --patch-every / --patch-where (in-place column writes, as a live element
  update does) and --extend-every-screens / --extend-width (append + trim on
  a fixed cadence that holds the strip's width).

No runtime behaviour changes: this is the measurement gate for live Vegas
elements.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* docs(changelog): note the frame-op attribution and bench modes

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* perf(scroll): build the strip's PIL image only when something reads it

Every Vegas strip extension rebuilt ScrollHelper.cached_image from
cached_array in full, twice (append, then trim), on the render thread:
Image.fromarray is 1.7ms for an 8,000px strip and 3.8ms for 20,000px on a
Pi 4 (measured on ledpi), about two thirds of an extension's render-thread
cost. Nothing on the frame path reads the image's pixels; every frame is cut
from the array.

cached_image is now a property. append_content and drop_scrolled_prefix
defer it; the first read builds it from the array it started with and keeps
it only if the strip has not changed meanwhile, so a sync push racing an
extension cannot leave a stale image cached. Assigning cached_image stores
exactly what was assigned, as before. has_strip() says whether there is a
strip without building its image; the helper's frame path, Vegas and the
adapter's scroll-cache invalidation use it. The strip is also no longer held
in memory twice.

In Vegas the image is now built only by a multi-display sync push.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* feat(vegas): live elements -- a plugin API for content that changes while it scrolls

Vegas bakes each plugin's pictures into one strip, so a card already on its
way across the panel keeps what it showed when it was drawn. This adds the
API and bookkeeping for content that can be updated in place; the worker
that redraws and swaps it follows separately. No shipped plugin implements
the hook yet, so nothing changes for users.

Plugin API (core 3.8.0), all no-ops by default:
- BasePlugin.get_vegas_elements() -> [VegasElement(key, image, version,
  live, refresh_hz)]: named, fixed-width pieces of Vegas content.
- BasePlugin.redraw_vegas_element(key, width, height, at): a lock-free
  redraw for content that changes with time.
- BasePlugin.notify_vegas_data_changed(): data that lands outside update().
- src/plugin_system/vegas_elements.py (VegasElement, re-exported from
  base_plugin).

Core:
- PluginAdapter asks a plugin that implements the hook for elements on the
  background fetch only (under its lock, on its own canvas); every other
  path keeps get_vegas_content(). Live elements are pinned (padded with
  content_padding, never trimmed), tagged with their key, digest and data
  epoch in Image.info so the existing cache and group plumbing carry them
  unchanged, and untagged if a width budget crops them.
- RenderPipeline records where each live element lands (ElementRecord), in
  absolute strip columns a trim does not move; the block-start arithmetic
  is shared with the STATIC markers.
- PluginManager update listeners (add/remove_update_listener,
  notify_data_changed): told the moment update() completes, not at the
  next ~4s Vegas poll. The coordinator uses one to move each plugin's data
  epoch on.
- vegas_scroll.live_refresh (kill switch), live_max_hz, live_min_interval,
  live_lead_screens; per-plugin core-owned vegas_live. Live elements are
  off under multi-display sync, in swap mode and with offscreen_prefetch off.
- scripts/check_plugin.py checks the element contract
  (src/plugin_system/testing/vegas.py); test/fixtures/plugins/vegas-live-stub
  is a working example.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* feat(vegas): live elements update in place while they scroll

One background worker (src/vegas_mode/live_worker.py) redraws a plugin's
live elements when its data epoch moves on (update listener) or on their
refresh_hz, nearest the screen first, and hands changed pixels lock-free to
the render thread, which copies them into the strip between frames
(RenderPipeline.apply_live_patches, ScrollHelper.patch_columns): at most
four patches or two screens of bytes a frame, no drawing or locks there.
The worker takes over group prefetch once a live element is placed, runs
inside the render gate, and is supervised. Update tick 1s while live
elements exist. Web UI switch for live_refresh. OFFSCREEN_RENDERING.md
describes what was built and why SegmentStrip was not needed.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* feat(sports): live Vegas cards for the scoreboards (shared layer)

One live element per game, drawn only when what the card shows changes, so
a score changes on a card already crossing the panel. The shared part, so
each scoreboard adopts it in a few lines:

- src/common/sports_vegas.py: game_key, game_fingerprint (the whole game
  dict, frozen: no drawn field can be missed), dedupe_games, VegasCardCache,
  StickyOdds (odds a live poll left out stay drawn), finished_games /
  with_finished_games (a game that just went final keeps its card, after its
  league's live games; one a heuristic only judged over keeps its live
  state, so a tied end of regulation never shows FINAL early).
- SportsScrollDisplay.make_vegas_renderer() is the override point;
  build_vegas_elements() and SportsScrollDisplayManager
  .get_vegas_elements_for() do the rest. A card's version includes its
  teams' ranks, which the renderer draws from the rankings cache.
- SportsLiveSharedMixin._record_finished_game() / finished_games_snapshot():
  held for FINISHED_GAME_TTL after it leaves the live list.

A sport that does not implement make_vegas_renderer keeps its ordinary Vegas
content, so no scoreboard changes until it opts in.

scripts/render_plugin.py --vegas renders a plugin's Vegas block as the
ticker lays it out, and --timeline stacks it at successive moments as
the ticker would update it in place; the join is now
render_pipeline.join_plugin_rows().

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* feat(vegas): keep live games in the ticker by default

display.vegas_scroll.live_in_ticker now defaults to true: through a live
game the marquee keeps running and the live scoreboard takes extra turns in
it -- its cards updating in place while they scroll -- instead of the ticker
giving way to the full-screen scoreboard.

The new default would reach nobody on its own: every existing config holds
an explicit false copied from the template (there was no control for it),
and the template merge only adds missing keys. ConfigManager therefore turns
a stored false on once, with a backup, and records live_in_ticker_migrated
so a false chosen afterwards stays. The marker is never in the template.

A "Keep live games in the ticker" checkbox under Vegas mode sets it. Tests
that pin the full-screen takeover now say live_in_ticker=false.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* feat(dev): preview a plugin's Vegas strip in the dev server

The dev server's View selector gains "Vegas strip (live elements)" and
"Vegas strip (plain Vegas content)": the plugin's block of the Vegas ticker,
laid out by the ticker's own code (render_vegas_strip, as render_plugin.py
--vegas uses), with its live elements listed. /api/render takes
"vegas": "live" | "plain"; the display view is unchanged.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* refactor(sports): a default _determine_game_type on SportsScrollDisplay

render_vegas_card looked the method up with getattr and a None default, which
static analysis (Codacy) reports as calling something that may not be
callable. The base class now has the default -- the card type from the game's
state -- and the plugins that define their own override it as before.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix: review follow-ups on the shared live-card layer

- The reused Vegas renderer always gets the current rankings, empty
  included, so ranks cleared since are not kept drawn.
- render_plugin.py: --timeline refuses --no-live (a timeline shows live
  elements changing), --timeline/--no-live need --vegas, and the Vegas
  paths create the output's directory like the display path does.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

scripts/dev_server.py

@@ -200,12 +200,21 @@ def api_plugin_defaults(plugin_id):
     return jsonify({'defaults': defaults})
 
 
+#: /api/render "vegas" values: the plugin's block of the Vegas strip, built
+#: from its live elements (falling back to its Vegas content, as the ticker
+#: does) or from its ordinary Vegas content only.
+VEGAS_VIEWS = ('live', 'plain')
+
+
 def _render_once(plugin_id, plugin_dir, manifest, config, mock_data, width, height,
-                 skip_update):
+                 skip_update, vegas=None):
     """Render one plugin at one size. Returns the /api/render response dict.
 
     A fresh plugin instance per call, mirroring the safety harness, so sizes
-    never share state.
+    never share state. With ``vegas`` set ('live' or 'plain') the image is the
+    plugin's block of the Vegas strip instead of its display(), laid out by
+    the ticker's own code (src/plugin_system/testing/vegas.py), and the
+    response lists where each live element sits in it.
     """
     from src.plugin_system.testing import VisualTestDisplayManager, MockCacheManager, MockPluginManager
     from src.plugin_system.plugin_loader import PluginLoader
@@ -243,6 +252,10 @@ def _render_once(plugin_id, plugin_dir, manifest, config, mock_data, width, heig
             logger.warning("update() raised for plugin %s", plugin_id, exc_info=True)
             warnings.append(f"update() raised: {type(e).__name__} — see server log")
 
+    if vegas:
+        return _vegas_response(plugin_id, plugin_instance, display_manager, vegas,
+                               start_time, errors, warnings)
+
     # Run display()
     try:
         plugin_instance.display(force_clear=True)
@@ -262,6 +275,40 @@ def _render_once(plugin_id, plugin_dir, manifest, config, mock_data, width, heig
     }
 
 
+def _vegas_response(plugin_id, plugin_instance, display_manager, vegas, start_time,
+                    errors, warnings):
+    """The /api/render response for the Vegas strip view."""
+    import base64
+    import io
+
+    from src.plugin_system.testing.vegas import render_vegas_strip
+
+    block, layout = None, []
+    try:
+        block, layout = render_vegas_strip(plugin_instance, plugin_id, display_manager,
+                                           live=(vegas == 'live'))
+    except Exception as e:
+        logger.warning("Vegas render raised for plugin %s", plugin_id, exc_info=True)
+        errors.append(f"Vegas render raised: {type(e).__name__} — see server log")
+    if block is None:
+        if not errors:
+            errors.append("The plugin has no Vegas content")
+        block = display_manager.image
+    elif vegas == 'live' and not layout:
+        warnings.append("No live elements: this is the plugin's ordinary Vegas content")
+    buffer = io.BytesIO()
+    block.convert('RGB').save(buffer, format='PNG')
+    return {
+        'image': 'data:image/png;base64,' + base64.b64encode(buffer.getvalue()).decode('ascii'),
+        'width': block.width,
+        'height': block.height,
+        'render_time_ms': round((time.time() - start_time) * 1000, 1),
+        'errors': errors,
+        'warnings': warnings,
+        'live_elements': [{'key': key, 'x': x, 'width': width} for x, key, width in layout],
+    }
+
+
 def _trusted_plugin_dir(plugin_dir: Path) -> Optional[Path]:
     """Re-derive a plugin directory from the search dirs' own listings.
 
@@ -333,6 +380,10 @@ def api_render():
     if not (MIN_HEIGHT <= height <= MAX_HEIGHT):
         return jsonify({'error': f'height must be between {MIN_HEIGHT} and {MAX_HEIGHT}'}), 400
 
+    vegas = data.get('vegas') or None
+    if vegas is not None and vegas not in VEGAS_VIEWS:
+        return jsonify({'error': f'vegas must be one of {", ".join(VEGAS_VIEWS)}'}), 400
+
     try:
         plugin_dir, manifest, config, mock_data, skip_update = _parse_render_request(data)
     except LookupError:
@@ -345,7 +396,7 @@ def api_render():
 
     try:
         result = _render_once(data['plugin_id'], plugin_dir, manifest, config,
-                              mock_data, width, height, skip_update)
+                              mock_data, width, height, skip_update, vegas=vegas)
     except Exception:
         app.logger.exception('plugin load failed during render')
         return jsonify({'error': 'Failed to load plugin; see server log'}), 500