Palette: seven roles (accent, good, caution added; highlight renamed alarm); no hard-coded colours left

background, foreground, subdued, accent (emphasis without danger), and the state
gradient good → caution → alarm; surface and onFill derived. smart-serow's
four-key themes still load (highlight = alarm; the new roles fall back).
Material's scheme follows: buttons in accent instead of the alarm colour.
Link state, mock banner, signal tiles, raw log, checklist button and marks,
camera page all take palette roles.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz

lib/theme/palette.dart

@@ -1,14 +1,22 @@
-// The palette system, from smart-serow's HUD: four semantic colours, each with a dark
-// (low ambient light) and a bright (high ambient light) variant, read from a theme
-// JSON in assets/themes/. Same file format as smart-serow's extra/themes/, so themes
-// move between the two as they are. Widgets ask for meanings, never for colours:
+// The palette system, from smart-serow's HUD, widened to seven roles: each a meaning,
+// each with a dark (low ambient light) and a bright (high ambient light) variant, read
+// from a theme JSON in assets/themes/. Widgets ask for meanings, never for colours:
 //
 //   final p = AppTheme.of(context);
 //   color: p.foreground
 //
+// The roles: background, foreground, subdued (muted), accent (emphasis without danger:
+// buttons, links, the current item), and the good → caution → alarm gradient for state.
+// Two more are derived, never authored: surface (raised bars and panels) and onFill
+// (text on a filled colour).
+//
+// smart-serow's four-key files load unchanged: their `highlight` is `alarm`, and the
+// three newer roles fall back (accent and good to foreground, caution to subdued).
+//
 // Pick the theme at build time: `--dart-define=YUKART_THEME=default` (default: rei, smart-serow's).
 
 import 'dart:convert';
+import 'dart:math' show max, min;
 
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
@@ -24,45 +32,87 @@ class Palette {
   const Palette({
     required this.background,
     required this.foreground,
-    required this.highlight,
     required this.subdued,
+    required this.accent,
+    required this.good,
+    required this.caution,
+    required this.alarm,
   });
 
   /// Behind everything.
   final Color background;
 
-  /// Values: what is read at a glance.
+  /// Values and primary text: what is read at a glance.
   final Color foreground;
 
-  /// Warnings, and the one thing that must be seen.
-  final Color highlight;
-
-  /// Labels, units, grids, and anything missing or stale.
+  /// Labels, units, grids, secondary text, and anything missing or stale.
   final Color subdued;
 
+  /// Emphasis without danger: buttons, links, the current item.
+  final Color accent;
+
+  /// Connected, done, healthy.
+  final Color good;
+
+  /// In progress, unconfirmed, mock data.
+  final Color caution;
+
+  /// Down, refused, destructive, over a limit: the one thing that must be seen.
+  final Color alarm;
+
+  /// Raised bars and panels: background with a little foreground mixed in.
+  Color get surface => Color.lerp(background, foreground, 0.08)!;
+
+  /// Text drawn on a filled [fill]: background or foreground, whichever contrasts more.
+  Color onFill(Color fill) {
+    double contrast(Color a, Color b) {
+      final (x, y) = (a.computeLuminance(), b.computeLuminance());
+      return (max(x, y) + 0.05) / (min(x, y) + 0.05);
+    }
+
+    return contrast(fill, background) >= contrast(fill, foreground)
+        ? background
+        : foreground;
+  }
+
   static Palette _fromJson(Map<String, dynamic> j) {
-    Color c(String k) =>
-        Color(0xFF000000 | int.parse((j[k] as String).substring(1), radix: 16));
+    Color? c(String k) => j[k] is String
+        ? Color(
+            0xFF000000 | int.parse((j[k] as String).substring(1), radix: 16),
+          )
+        : null;
+    final foreground = c('foreground')!;
+    final subdued = c('subdued')!;
     return Palette(
-      background: c('background'),
-      foreground: c('foreground'),
-      highlight: c('highlight'),
-      subdued: c('subdued'),
+      background: c('background')!,
+      foreground: foreground,
+      subdued: subdued,
+      accent: c('accent') ?? foreground,
+      good: c('good') ?? foreground,
+      caution: c('caution') ?? subdued,
+      // smart-serow calls it highlight.
+      alarm: (c('alarm') ?? c('highlight'))!,
     );
   }
 
-  /// smart-serow's hard-coded last resort, used when no theme file loads.
+  /// The last resort, used when no theme file loads (smart-serow's four, plus three).
   static const fallbackDark = Palette(
     background: Color(0xFF000000),
     foreground: Color(0xFFFFFFFF),
-    highlight: Color(0xFFFF5555),
     subdued: Color(0xFF808080),
+    accent: Color(0xFF5EC8F2),
+    good: Color(0xFF6CCB5F),
+    caution: Color(0xFFFFC107),
+    alarm: Color(0xFFFF5555),
   );
   static const fallbackBright = Palette(
     background: Color(0xFFF0F0F0),
     foreground: Color(0xFF1A1A1A),
-    highlight: Color(0xFFCC0000),
     subdued: Color(0xFF606060),
+    accent: Color(0xFF0277BD),
+    good: Color(0xFF2E7D32),
+    caution: Color(0xFF8D6E00),
+    alarm: Color(0xFFCC0000),
   );
 }
 
@@ -106,7 +156,8 @@ class Themes extends ChangeNotifier {
     return Themes('fallback', Palette.fallbackDark, Palette.fallbackBright);
   }
 
-  /// Material's theme for the rest of the app, from the same four colours.
+  /// Material's theme for the rest of the app, from the same roles: buttons and
+  /// selection in accent, errors in alarm, raised surfaces in surface.
   ThemeData material() {
     final p = current;
     final brightness = _isDark ? Brightness.dark : Brightness.light;
@@ -116,13 +167,20 @@ class Themes extends ChangeNotifier {
       scaffoldBackgroundColor: p.background,
       colorScheme:
           ColorScheme.fromSeed(
-            seedColor: p.highlight,
+            seedColor: p.accent,
             brightness: brightness,
           ).copyWith(
             surface: p.background,
             onSurface: p.foreground,
-            primary: p.highlight,
-            error: p.highlight,
+            surfaceContainerHigh: p.surface,
+            surfaceContainerHighest: p.surface,
+            primary: p.accent,
+            onPrimary: p.onFill(p.accent),
+            primaryContainer: Color.lerp(p.background, p.accent, 0.25),
+            onPrimaryContainer: p.foreground,
+            secondary: p.accent,
+            error: p.alarm,
+            onError: p.onFill(p.alarm),
             outline: p.subdued,
             onSurfaceVariant: p.subdued,
           ),