feat(app): add flow diagnostics and refine interface

Improve failure recovery visibility, strengthen account-session handling, and make the cross-platform interface more consistent.

OSGKeyboardMac/MacComponents.swift

@@ -104,9 +104,9 @@ struct MacToggleStyle: ToggleStyle {
                 Capsule()
                     .fill(configuration.isOn ? palette.accent : offTrackColor)
                 Circle()
-                    .fill(Color.white)
+                    .fill(OSGColor.macToggleKnob)
                     .frame(width: 16, height: 16)
-                    .shadow(color: .black.opacity(0.25), radius: 1, y: 1)
+                    .shadow(color: OSGColor.macToggleKnobShadow, radius: 1, y: 1)
                     .padding(2)
             }
             .frame(width: 36, height: 20)
@@ -117,8 +117,8 @@ struct MacToggleStyle: ToggleStyle {
 
     private var offTrackColor: Color {
         colorScheme == .dark
-            ? Color.white.opacity(0.18)
-            : Color.black.opacity(0.15)
+            ? OSGColor.macToggleOffTrackDark
+            : OSGColor.macToggleOffTrackLight
     }
 }
 
@@ -411,7 +411,7 @@ struct MacHeaderActionButtonStyle: ButtonStyle {
         configuration.label
             .padding(.horizontal, Spacing.md)
             .frame(height: MacMetrics.pageHeaderControlHeight)
-            .foregroundStyle(.white)
+            .foregroundStyle(OSGColor.fixedLightContent)
             .background(
                 palette.accent.opacity(configuration.isPressed ? 0.82 : 1),
                 in: Capsule()

OSGKeyboardMac/MacDictationOverlayView.swift

@@ -71,7 +71,7 @@ struct MacDictationOverlayView: View {
             Capsule(style: .continuous)
                 .stroke(palette.dividerStrong, lineWidth: 0.5)
         )
-        .shadow(color: Color.black.opacity(0.22), radius: 14, y: 5)
+        .shadow(color: OSGColor.macOverlayShadow, radius: 14, y: 5)
         .padding(Self.shadowMargin)
         .contentShape(Capsule(style: .continuous))
         // Manual drag: `isMovableByWindowBackground` doesn't work on a

OSGKeyboardMac/MacDictionaryView.swift

@@ -173,7 +173,7 @@ struct MacDictionaryView: View {
         }
         .padding(.horizontal, Spacing.sm)
         .frame(width: 220, height: MacMetrics.pageHeaderControlHeight)
-        .background(palette.surface, in: Capsule())
+        .background(palette.formSurface, in: Capsule())
         .overlay(Capsule().stroke(palette.divider, lineWidth: 0.5))
     }
 
@@ -289,9 +289,13 @@ private struct MacDictionaryEntryEditor: View {
                 Button(MacL10n.string("mac.cancel", language: language)) {
                     dismiss()
                 }
-                Button(MacL10n.string("mac.save", language: language), action: save)
+                .tint(palette.textPrimary)
+                Button(action: save) {
+                    Text(MacL10n.string("mac.save", language: language))
+                        .foregroundStyle(palette.background)
+                }
                     .buttonStyle(.borderedProminent)
-                    .tint(palette.accent)
+                    .tint(palette.textPrimary)
                     .disabled(trimmedTerm.isEmpty)
             }
         }

OSGKeyboardMac/MacLocalASRModelSettingsView.swift

@@ -385,7 +385,7 @@ struct MacLocalASRModelSettingsView: View {
             MacSettingsToolButton(
                 title: MacL10n.string("mac.localASR.download", language: lang),
                 fill: palette.accent,
-                foreground: .white
+                foreground: OSGColor.fixedLightContent
             ) {
                 modelVM.installModel(model)
             }

OSGKeyboardMac/MacOnboardingView.swift

@@ -272,7 +272,9 @@ struct MacOnboardingView: View {
                     .resizable()
                     .scaledToFit()
                     .frame(width: 128, height: 128)
-                    .foregroundStyle(colorScheme == .dark ? Color.white : palette.accent)
+                    .foregroundStyle(
+                        colorScheme == .dark ? OSGColor.fixedLightContent : palette.accent
+                    )
                     .accessibilityLabel("OSGKeyboard")
                     .allowsHitTesting(false)
             }

OSGKeyboardMac/MacPolishStylesView.swift

@@ -514,7 +514,7 @@ private struct MacPolishStyleEditor: View {
                 .font(.body.monospaced())
                 .frame(minHeight: 320)
                 .padding(4)
-                .background(palette.surface, in: RoundedRectangle(cornerRadius: Radius.medium))
+                .background(palette.formSurface, in: RoundedRectangle(cornerRadius: Radius.medium))
                 .overlay(
                     RoundedRectangle(cornerRadius: Radius.medium)
                         .stroke(palette.divider, lineWidth: 1)

OSGKeyboardMac/MacSettingsComponents.swift

@@ -421,14 +421,14 @@ struct MacProviderModelRow: View {
             HStack(spacing: Spacing.sm) {
                 Text(modelId)
                     .font(TypeStyle.mono)
-                    .foregroundStyle(isSelected ? palette.accent : palette.textPrimary)
+                    .foregroundStyle(palette.textPrimary)
                     .lineLimit(1)
                     .truncationMode(.middle)
                 Spacer(minLength: 0)
                 if isSelected {
                     Image(systemName: "checkmark")
                         .font(.system(size: 11, weight: .semibold))
-                        .foregroundStyle(palette.accent)
+                        .foregroundStyle(palette.textPrimary)
                 }
             }
             .padding(.horizontal, Spacing.sm)
@@ -436,7 +436,7 @@ struct MacProviderModelRow: View {
             .frame(maxWidth: .infinity, alignment: .leading)
             .background(
                 RoundedRectangle(cornerRadius: Radius.small, style: .continuous)
-                    .fill(isSelected ? palette.accentMuted : Color.clear)
+                    .fill(isSelected ? palette.textPrimary.opacity(0.10) : Color.clear)
             )
             .contentShape(Rectangle())
         }

OSGKeyboardMac/MacSupportDeveloperTipRows.swift

@@ -56,6 +56,7 @@ struct MacSupportDeveloperTipRows: View {
             Button(SharedL10n.string("tip.alert.dismiss", language: language)) {
                 tipManager.acknowledgePurchaseState()
             }
+            .tint(palette.textPrimary)
         } message: {
             Text(SharedL10n.string("tip.thankYou.message", language: language))
         }
@@ -66,6 +67,7 @@ struct MacSupportDeveloperTipRows: View {
             Button(SharedL10n.string("tip.alert.dismiss", language: language)) {
                 tipManager.acknowledgePurchaseState()
             }
+            .tint(palette.textPrimary)
         } message: {
             Text(errorMessage)
         }

OSGKeyboardMac/MacTheme.swift

@@ -30,6 +30,7 @@ enum MacSystemPalette {
         ThemePalette(
             background: resolved(dark ? darkBackground : warmBackground, dark: dark),
             surface: resolved(dark ? darkSurface : warmSurface, dark: dark),
+            formSurface: resolved(dark ? darkFormSurface : warmFormSurface, dark: dark),
             surfaceElevated: resolved(dark ? darkElevated : warmElevated, dark: dark),
             surfaceMuted: resolved(dark ? darkMuted : warmMuted, dark: dark),
 
@@ -45,14 +46,14 @@ enum MacSystemPalette {
             textPrimary: resolved(.labelColor, dark: dark),
             textSecondary: resolved(.secondaryLabelColor, dark: dark),
             textTertiary: resolved(.tertiaryLabelColor, dark: dark),
-            textOnAccent: Color.white,
+            textOnAccent: OSGColor.fixedLightContent,
 
             divider: dark
-                ? Color.white.opacity(0.08)
-                : Color.black.opacity(0.06),
+                ? OSGColor.macDarkDivider
+                : OSGColor.lightDivider,
             dividerStrong: dark
-                ? Color.white.opacity(0.12)
-                : Color.black.opacity(0.10),
+                ? OSGColor.macDarkDividerStrong
+                : OSGColor.lightDividerStrong,
 
             recordRed: resolved(.systemRed, dark: dark),
             recordBlue: resolved(.systemBlue, dark: dark)
@@ -62,13 +63,15 @@ enum MacSystemPalette {
     // MARK: - Warm Light-mode surfaces (matched to iOS `Palette.light`)
 
     /// #F2F1EE — warm gray page background.
-    private static let warmBackground = NSColor(srgbRed: 0.949, green: 0.945, blue: 0.933, alpha: 1)
+    private static let warmBackground = NSColor(OSGColor.lightBackground)
     /// #FCFBF9 — warm off-white card/control surface.
-    private static let warmSurface = NSColor(srgbRed: 0.988, green: 0.984, blue: 0.976, alpha: 1)
+    private static let warmSurface = NSColor(OSGColor.lightSurface)
+    /// #FCFBF9 — forms retain the ordinary card fill in light mode.
+    private static let warmFormSurface = warmSurface
     /// #EBEAE7 — slightly recessed elevated surface.
-    private static let warmElevated = NSColor(srgbRed: 0.922, green: 0.918, blue: 0.906, alpha: 1)
+    private static let warmElevated = NSColor(OSGColor.lightSurfaceElevated)
     /// #EEEDE9 — muted fill between background and surface.
-    private static let warmMuted = NSColor(srgbRed: 0.933, green: 0.929, blue: 0.918, alpha: 1)
+    private static let warmMuted = NSColor(OSGColor.lightSurfaceMuted)
 
     // MARK: - Dark-mode surfaces (Apple standard elevated grays)
     //
@@ -78,13 +81,15 @@ enum MacSystemPalette {
     // clearly elevated above the background — mirroring the iOS dark palette.
 
     /// #1C1C1E — page background.
-    private static let darkBackground = NSColor(srgbRed: 0.110, green: 0.110, blue: 0.118, alpha: 1)
+    private static let darkBackground = NSColor(OSGColor.macDarkBackground)
     /// #2C2C2E — card / control surface, clearly lighter than the background.
-    private static let darkSurface = NSColor(srgbRed: 0.173, green: 0.173, blue: 0.180, alpha: 1)
+    private static let darkSurface = NSColor(OSGColor.macDarkSurface)
+    /// #343438 — interactive form fill between cards and elevated chrome.
+    private static let darkFormSurface = NSColor(OSGColor.macDarkFormSurface)
     /// #3A3A3C — elevated fill for selected / raised chrome.
-    private static let darkElevated = NSColor(srgbRed: 0.227, green: 0.227, blue: 0.235, alpha: 1)
+    private static let darkElevated = NSColor(OSGColor.macDarkSurfaceElevated)
     /// #242426 — muted fill between background and surface.
-    private static let darkMuted = NSColor(srgbRed: 0.141, green: 0.141, blue: 0.149, alpha: 1)
+    private static let darkMuted = NSColor(OSGColor.macDarkSurfaceMuted)
 
     /// Resolves a (possibly dynamic) AppKit colour to its concrete value under
     /// the requested appearance, so the two static palettes differ by value.