Vegas mode: render plugins narrower, space rows by measured separation

Trimming reclaims blank margins but cannot compact a layout that genuinely
spans the display — a five-column forecast, a progress bar drawn at 100%
width, a stat block with the panel's whole width between its elements. Those
need the plugin to make different layout decisions, which means telling it the
screen is narrower while it renders.

DisplayManager.render_size() presents a smaller logical canvas for the
duration of a Vegas content fetch, reusing the same _LogicalMatrix
indirection double-sided mode already relies on so plugins see a consistent
size from every accessor. Plugins that size themselves from matrix.width need
no changes at all; one that wants to be explicit can read the new
BasePlugin.get_vegas_render_width().

Width is a percentage so a single setting travels across panel sizes:
vegas_scroll.render_width_pct globally, or vegas_width_pct in an individual
plugin's config. Measured on a 512x64 panel with real data:

  ledmatrix-weather   1536px -> 576px   (forecast becomes narrow cards)
  youtube-stats        353px -> 199px   (2% blank left, so genuinely compact)
  geochron             453px -> 153px   (ink density rises to 100%)
  ledmatrix-flights    950px -> 740px

The youtube-stats figure is the clearest evidence the layout itself changed
rather than being cropped: at full width the content had to be trimmed from
512px to 353px, whereas at 40% it arrives with almost no blank to reclaim.

Row spacing is now measured rather than added. A flat gap gets it wrong in
both directions at once — content drawn flush to its own edges ends up nearly
touching (reported for recent sports scores, which sat 8px apart), while
content already carrying wide margins gets pushed even further out.
separation_gap() measures the blank each pair already has and adds only the
shortfall, up to min_content_separation (default 24). intra_plugin_gap stays
as a floor applied regardless.

Two tests shipped in the previous commit encoded the old flat-gap arithmetic
and are updated to the measured semantics, including one renamed to reflect
that zero intra_plugin_gap alone no longer butts rows together.

Also fixes a real bug found while testing: the harness display manager had no
render_size(), and because the adapter catches broadly that surfaced as "no
content" rather than an error, silently dropping five plugins. Added the
context to VisualTestDisplayManager for parity, and _render_at() now degrades
to a no-op on any display manager lacking it, so a third-party or older
harness loses the narrowing rather than the content.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KEZK1P1Q1fu5pcuVrkrCFZ

web_interface/blueprints/api_v3.py

@@ -923,7 +923,8 @@ def save_main_config():
                        'vegas_min_plugin_width', 'vegas_lead_in_width', 'vegas_plugins_per_cycle',
                        'vegas_max_plugin_width_ratio', 'vegas_dynamic_duration_enabled',
                        'vegas_min_cycle_duration', 'vegas_max_cycle_duration',
-                       'vegas_intra_plugin_gap']
+                       'vegas_intra_plugin_gap', 'vegas_render_width_pct',
+                       'vegas_min_content_separation']
 
         if any(k in data for k in vegas_fields):
             if 'display' not in current_config:
@@ -974,6 +975,8 @@ def save_main_config():
                 'vegas_scroll_speed': ('scroll_speed', 1, 200),
                 'vegas_separator_width': ('separator_width', 0, 128),
                 'vegas_intra_plugin_gap': ('intra_plugin_gap', 0, 128),
+                'vegas_render_width_pct': ('render_width_pct', 10, 100),
+                'vegas_min_content_separation': ('min_content_separation', 0, 256),
                 'vegas_target_fps': ('target_fps', 30, 200),
                 'vegas_buffer_ahead': ('buffer_ahead', 1, 5),
                 'vegas_trim_threshold': ('trim_threshold', 0, 254),

web_interface/templates/v3/partials/display.html

@@ -438,7 +438,7 @@
 
                 <div class="grid grid-cols-1 md:grid-cols-2 gap-4">
                     <div class="form-group" id="setting-display-vegas_intra_plugin_gap" data-setting-key="display.vegas_scroll.intra_plugin_gap">
-                        <label for="vegas_intra_plugin_gap" class="block text-sm font-medium text-gray-700">Row Gap (pixels){{ ui.help_tip('Gap between rows contributed by the same plugin (0–128 px).\nDefault: 8. Multi-row plugins such as sports scoreboards, news feeds and the F1 standings return one image per row; this keeps those rows close together while Separator Width still marks the jump to the next plugin. Set 0 to butt rows directly together.', 'Row Gap') }}</label>
+                        <label for="vegas_intra_plugin_gap" class="block text-sm font-medium text-gray-700">Row Gap (pixels){{ ui.help_tip('Extra gap always added between rows contributed by the same plugin (0–128 px).\nDefault: 8. This is a floor on top of Row Separation below, which does most of the work. Set both to 0 to butt rows directly together.', 'Row Gap') }}</label>
                         <input type="number"
                                id="vegas_intra_plugin_gap"
                                name="vegas_intra_plugin_gap"
@@ -447,6 +447,31 @@
                                max="128"
                                class="form-control">
                     </div>
+
+                    <div class="form-group" id="setting-display-vegas_min_content_separation" data-setting-key="display.vegas_scroll.min_content_separation">
+                        <label for="vegas_min_content_separation" class="block text-sm font-medium text-gray-700">Row Separation (pixels){{ ui.help_tip('Blank space guaranteed between rows of the same plugin, measured from the actual content rather than added blindly (0–256 px).\nDefault: 24. Rows already carrying wide margins get nothing added; rows drawn right up to their own edges — sports score cards, for instance — get the full amount, so they no longer look like they are touching. Raise it if items still feel cramped.', 'Row Separation') }}</label>
+                        <input type="number"
+                               id="vegas_min_content_separation"
+                               name="vegas_min_content_separation"
+                               value="{{ main_config.display.get('vegas_scroll', {}).get('min_content_separation', 24) }}"
+                               min="0"
+                               max="256"
+                               class="form-control">
+                    </div>
+                </div>
+
+                <div class="grid grid-cols-1 md:grid-cols-2 gap-4">
+                    <div class="form-group" id="setting-display-vegas_render_width_pct" data-setting-key="display.vegas_scroll.render_width_pct">
+                        <label for="vegas_render_width_pct" class="block text-sm font-medium text-gray-700">Plugin Render Width (%){{ ui.help_tip('How much of the screen width each plugin is told it has while drawing for the ticker (10–100%).\nDefault: 100 (unchanged). Lowering it makes plugins choose a tighter layout rather than being cropped — a weather forecast becomes narrow cards instead of five columns spread across the panel. Useful on wide displays. Override per plugin with the vegas_width_pct setting in that plugin\'s own configuration.', 'Plugin Render Width') }}</label>
+                        <input type="number"
+                               id="vegas_render_width_pct"
+                               name="vegas_render_width_pct"
+                               value="{{ main_config.display.get('vegas_scroll', {}).get('render_width_pct', 100) }}"
+                               min="10"
+                               max="100"
+                               step="5"
+                               class="form-control">
+                    </div>
                 </div>
 
                 <div class="grid grid-cols-1 md:grid-cols-2 gap-4">