feat(themes): dedicated code-syntax palette keys

Code highlighting reused brand tokens (accent/text/border/muted), so it couldn't
be themed independently. Add syntax_string/number/keyword/comment skin keys →
syntax* theme tokens (defaulting to those brand tokens, so defaults are
unchanged) and point the highlighter at them. Documented in the element→key map.

apps/shared/src/skin.ts

@@ -44,6 +44,10 @@ export const SKIN_COLOR_TOKENS = [
   'diff_removed',
   'diff_added_word',
   'diff_removed_word',
+  'syntax_string',
+  'syntax_number',
+  'syntax_keyword',
+  'syntax_comment',
   // CLI / TUI chrome.
   'prompt',
   'input_rule',

hermes_cli/skin_engine.py

@@ -42,6 +42,10 @@ All fields are optional. Missing values inherit from the ``default`` skin.
       diff_removed: "#ffdcdc"            # Diff removed-line background
       diff_added_word: "#248a3d"         # Diff added word-level foreground
       diff_removed_word: "#cf222e"       # Diff removed word-level foreground
+      syntax_string: "#FFBF00"           # Code strings; falls back to ui_accent
+      syntax_number: "#FFF8DC"           # Code numbers; falls back to ui_text
+      syntax_keyword: "#CD7F32"          # Code keywords; falls back to ui_border
+      syntax_comment: "#CC9B1F"          # Code comments; falls back to banner_dim
       prompt: "#FFF8DC"                  # Prompt text color
       input_rule: "#CD7F32"              # Input area horizontal rule
       response_border: "#FFD700"         # Response box border (ANSI)

skills/hermes-themes/SKILL.md

@@ -61,6 +61,7 @@ key in its row (element-specific keys fall back to the shared one when unset).
 | Success / warn / error | `ui_ok` / `ui_warn` / `ui_error` | — |
 | Status bar text + usage | `status_bar_text`, `status_bar_good/warn/bad/critical` | — |
 | Diff add/remove (line + word) | `diff_added` / `diff_removed` / `diff_added_word` / `diff_removed_word` | built-in |
+| Code syntax (string/number/keyword/comment) | `syntax_string` / `syntax_number` / `syntax_keyword` / `syntax_comment` | accent/text/border/muted |
 | Completion menu | `completion_menu_bg` / `completion_menu_current_bg` / `…_meta_bg` | — |
 
 Note the sharing: `ui_accent` colors tool markers **and** headings/links/chevrons,

ui-tui/src/__tests__/theme.test.ts

@@ -548,6 +548,23 @@ describe('background-aware adaptation (OSC-11 light terminals)', () => {
     expect(fallback.color.thinking).toBe('#123456')
   })
 
+  it('gives code syntax its own keys, defaulting to accent/text/border/muted', async () => {
+    const { fromSkin } = await importThemeWithCleanEnv()
+
+    const themed = fromSkin(
+      { syntax_string: '#aa0000', syntax_number: '#00aa00', syntax_keyword: '#0000aa', syntax_comment: '#888888' },
+      {}
+    )
+
+    expect(themed.color.syntaxString).toBe('#aa0000')
+    expect(themed.color.syntaxNumber).toBe('#00aa00')
+    expect(themed.color.syntaxKeyword).toBe('#0000aa')
+    expect(themed.color.syntaxComment).toBe('#888888')
+
+    const fallback = fromSkin({ ui_accent: '#abcdef' }, {})
+    expect(fallback.color.syntaxString).toBe('#abcdef') // string follows accent
+  })
+
   it('lets skins override diff colors', async () => {
     const { fromSkin } = await importThemeWithCleanEnv()
 

ui-tui/src/lib/syntax.ts

@@ -80,7 +80,7 @@ export function highlightLine(line: string, lang: string, t: Theme): Token[] {
   }
 
   if (spec.comment && line.trimStart().startsWith(spec.comment)) {
-    return [[t.color.muted, line]]
+    return [[t.color.syntaxComment, line]]
   }
 
   const tokens: Token[] = []
@@ -97,11 +97,11 @@ export function highlightLine(line: string, lang: string, t: Theme): Token[] {
     const ch = tok[0]!
 
     if (ch === '"' || ch === "'" || ch === '`') {
-      tokens.push([t.color.accent, tok])
+      tokens.push([t.color.syntaxString, tok])
     } else if (ch >= '0' && ch <= '9') {
-      tokens.push([t.color.text, tok])
+      tokens.push([t.color.syntaxNumber, tok])
     } else if (spec.keywords.has(tok)) {
-      tokens.push([t.color.border, tok])
+      tokens.push([t.color.syntaxKeyword, tok])
     } else {
       tokens.push(['', tok])
     }

ui-tui/src/theme.ts

@@ -23,6 +23,12 @@ export interface ThemeColors {
   /** Reasoning/thinking body text. Defaults to `muted`. */
   thinking: string
 
+  /** Code-block syntax highlight. Default to accent/text/border/muted. */
+  syntaxString: string
+  syntaxNumber: string
+  syntaxKeyword: string
+  syntaxComment: string
+
   prompt: string
   sessionLabel: string
   sessionBorder: string
@@ -310,6 +316,13 @@ export function buildPalette(seeds: ThemeSeeds, isLight: boolean): ThemeColors {
     tool: seeds.accent,
     thinking: muted,
 
+    // Code-syntax tokens default to brand tokens (unchanged highlighting)
+    // but are independently skinnable.
+    syntaxString: seeds.accent,
+    syntaxNumber: seeds.text,
+    syntaxKeyword: seeds.border ?? tones.border,
+    syntaxComment: muted,
+
     prompt: seeds.prompt ?? seeds.text,
     // sessionLabel/sessionBorder track the muted tone — "same role, same
     // colour" by design (#11300).
@@ -855,7 +868,12 @@ export function fromSkin(
     diffAdded: c('diff_added') ?? derived.diffAdded,
     diffRemoved: c('diff_removed') ?? derived.diffRemoved,
     diffAddedWord: c('diff_added_word') ?? derived.diffAddedWord,
-    diffRemovedWord: c('diff_removed_word') ?? derived.diffRemovedWord
+    diffRemovedWord: c('diff_removed_word') ?? derived.diffRemovedWord,
+    // Code-syntax tokens: overridable, else the derived brand-token defaults.
+    syntaxString: c('syntax_string') ?? derived.syntaxString,
+    syntaxNumber: c('syntax_number') ?? derived.syntaxNumber,
+    syntaxKeyword: c('syntax_keyword') ?? derived.syntaxKeyword,
+    syntaxComment: c('syntax_comment') ?? derived.syntaxComment
   }
 
   // 4. Guard: contrast floors against the real background + fill polarity.