fix(tui): keep the Apple Terminal dim fallback inside the active palette

Terminal.app ignores SGR 2, so dim is substituted with a literal color.
That color was hardcoded to #6B7280 — a cold slate that belongs to no
theme. Next to themed text on the same line it reads as a second,
foreign foreground: on a light profile, gray words beside near-black
ones.

Make the tone theme-supplied via setDimFallbackColor, fed the active
muted tone from the same effect that already publishes selectionBg.
#6B7280 stays as the pre-theme boot default so the first frame is
unchanged, and terminals that honor SGR 2 are untouched.

ui-tui/packages/hermes-ink/src/entry-exports.ts

@@ -10,7 +10,7 @@ export { NoSelect } from './ink/components/NoSelect.js'
 export { RawAnsi } from './ink/components/RawAnsi.js'
 export { default as ScrollBox } from './ink/components/ScrollBox.js'
 export { default as Spacer } from './ink/components/Spacer.js'
-export { default as Text } from './ink/components/Text.js'
+export { setDimFallbackColor, default as Text } from './ink/components/Text.js'
 export { default as useApp } from './ink/hooks/use-app.js'
 export { useCursorAdvance } from './ink/hooks/use-cursor-advance.js'
 export { useDeclaredCursor } from './ink/hooks/use-declared-cursor.js'

ui-tui/packages/hermes-ink/src/ink/components/Text.test.ts

@@ -1,6 +1,6 @@
-import { describe, expect, it } from 'vitest'
+import { afterEach, describe, expect, it } from 'vitest'
 
-import { dimColorFallback, shouldUseAnsiDim } from './Text.js'
+import { dimColorFallback, setDimFallbackColor, shouldUseAnsiDim } from './Text.js'
 
 describe('shouldUseAnsiDim', () => {
   it('disables ANSI dim on VTE terminals by default', () => {
@@ -23,6 +23,10 @@ describe('shouldUseAnsiDim', () => {
 })
 
 describe('dimColorFallback', () => {
+  afterEach(() => {
+    setDimFallbackColor(undefined)
+  })
+
   it('renders Apple Terminal dim as muted gray by default', () => {
     expect(dimColorFallback({ TERM_PROGRAM: 'Apple_Terminal' } as NodeJS.ProcessEnv)).toBe('#6B7280')
   })
@@ -39,4 +43,23 @@ describe('dimColorFallback', () => {
       dimColorFallback({ HERMES_TUI_DIM: '0', TERM_PROGRAM: 'Apple_Terminal' } as NodeJS.ProcessEnv)
     ).toBeUndefined()
   })
+
+  it('uses the theme tone once one is supplied, so dim stays in-palette', () => {
+    setDimFallbackColor('#936e06')
+
+    expect(dimColorFallback({ TERM_PROGRAM: 'Apple_Terminal' } as NodeJS.ProcessEnv)).toBe('#936e06')
+  })
+
+  it('falls back to the boot default when the theme tone is cleared', () => {
+    setDimFallbackColor('#936e06')
+    setDimFallbackColor(undefined)
+
+    expect(dimColorFallback({ TERM_PROGRAM: 'Apple_Terminal' } as NodeJS.ProcessEnv)).toBe('#6B7280')
+  })
+
+  it('stays inert on terminals that honor SGR 2, whatever the theme tone', () => {
+    setDimFallbackColor('#936e06')
+
+    expect(dimColorFallback({ TERM: 'xterm-256color' } as NodeJS.ProcessEnv)).toBeUndefined()
+  })
 })

ui-tui/packages/hermes-ink/src/ink/components/Text.tsx

@@ -84,6 +84,19 @@ export function shouldUseAnsiDim(env: NodeJS.ProcessEnv = process.env): boolean
   return !env.VTE_VERSION
 }
 
+/**
+ * Terminals that ignore SGR 2 need a literal color instead. The tone is
+ * theme-supplied (setDimFallbackColor, called from the theme effect) so it
+ * stays inside the active palette; the slate below is only the pre-theme
+ * boot default. A hardcoded value here reads as an off-palette foreground
+ * next to themed spans on the same line — cold gray beside warm ink.
+ */
+let dimFallbackColor: Color = LEGACY_APPLE_DIM_COLOR
+
+export function setDimFallbackColor(color: Color | undefined): void {
+  dimFallbackColor = color || LEGACY_APPLE_DIM_COLOR
+}
+
 export function dimColorFallback(env: NodeJS.ProcessEnv = process.env): Color | undefined {
   const override = (env.HERMES_TUI_DIM ?? '').trim()
 
@@ -91,7 +104,7 @@ export function dimColorFallback(env: NodeJS.ProcessEnv = process.env): Color |
     return undefined
   }
 
-  return (env.TERM_PROGRAM ?? '').trim() === 'Apple_Terminal' ? LEGACY_APPLE_DIM_COLOR : undefined
+  return (env.TERM_PROGRAM ?? '').trim() === 'Apple_Terminal' ? dimFallbackColor : undefined
 }
 
 const memoizedStylesForWrap: Record<NonNullable<Styles['textWrap']>, Styles> = {

ui-tui/src/app/useMainApp.ts

@@ -1,6 +1,7 @@
 import {
   forceRedraw,
   type ScrollBoxHandle,
+  setDimFallbackColor,
   useApp,
   useHasSelection,
   useSelection,
@@ -245,6 +246,14 @@ export function useMainApp(gw: GatewayClient) {
     selection.setSelectionBgColor(ui.theme.color.selectionBg)
   }, [selection, ui.theme.color.selectionBg])
 
+  // Terminals that ignore SGR 2 (Apple_Terminal) get a literal color for
+  // `dim` instead. Feed it the theme's muted tone so dimmed spans stay in
+  // the palette — a hardcoded gray renders as a foreign foreground next to
+  // themed text on the same line.
+  useEffect(() => {
+    setDimFallbackColor(ui.theme.color.muted)
+  }, [ui.theme.color.muted])
+
   // macOS Terminal.app does not forward Cmd+C to fullscreen TUIs that enable
   // mouse tracking, so the only reliable native-feeling path is iTerm-style
   // copy-on-select: once a drag creates a stable TUI selection, write it to

ui-tui/src/types/hermes-ink.d.ts

@@ -104,6 +104,7 @@ declare module '@hermes/ink' {
   export const NoSelect: React.ComponentType<any>
   export const ScrollBox: React.ComponentType<any>
   export const Text: React.ComponentType<any>
+  export function setDimFallbackColor(color: string | undefined): void
   export const TextInput: React.ComponentType<any>
   export const stringWidth: (s: string) => number
   export function isXtermJs(): boolean