fix(tui): split terminal tab title from window title

Terminal.app truncates background tab titles from the left, so a single
long OSC 0 string (marker · session · model · cwd) leaves only the tail
visible — usually the cwd or process name. Emit OSC 1 (icon/tab) with
just the short session title and OSC 2 (window) with the full composed
string, so background tabs show the session name instead of the cwd tail.

ui-tui/packages/hermes-ink/index.d.ts

@@ -29,6 +29,7 @@ export { default as useStdin } from './src/ink/hooks/use-stdin.ts'
 export { useTabStatus } from './src/ink/hooks/use-tab-status.ts'
 export { useTerminalFocus } from './src/ink/hooks/use-terminal-focus.ts'
 export { useTerminalTitle } from './src/ink/hooks/use-terminal-title.ts'
+export type { TerminalTitlePair } from './src/ink/hooks/use-terminal-title.ts'
 export { useTerminalViewport } from './src/ink/hooks/use-terminal-viewport.ts'
 export { default as measureElement } from './src/ink/measure-element.ts'
 export { createRoot, forceRedraw, default as render, renderSync } from './src/ink/root.ts'

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

@@ -21,6 +21,7 @@ export { default as useStdin } from './ink/hooks/use-stdin.js'
 export { useTabStatus } from './ink/hooks/use-tab-status.js'
 export { useTerminalFocus } from './ink/hooks/use-terminal-focus.js'
 export { useTerminalTitle } from './ink/hooks/use-terminal-title.js'
+export type { TerminalTitlePair } from './ink/hooks/use-terminal-title.js'
 export { useTerminalViewport } from './ink/hooks/use-terminal-viewport.js'
 export { default as measureElement } from './ink/measure-element.js'
 export { scrollFastPathStats, type ScrollFastPathStats } from './ink/render-node-to-output.js'

ui-tui/packages/hermes-ink/src/ink/hooks/use-terminal-title.ts

@@ -7,15 +7,20 @@ import { TerminalWriteContext } from '../useTerminalNotification.js'
 /**
  * Declaratively set the terminal tab/window title.
  *
- * Pass a string to set the title. ANSI escape sequences are stripped
- * automatically so callers don't need to know about terminal encoding.
+ * Pass a single string to set both the tab and window title (OSC 0).
+ * Pass `{ tab, window }` to set them independently: the short `tab` string
+ * goes to OSC 1 (icon/tab label) and the longer `window` string goes to
+ * OSC 2 (window title bar). This matters for terminals like Apple
+ * Terminal.app whose narrow background tabs truncate the title from the
+ * left — a single long OSC 0 string leaves only the tail visible, while a
+ * separate short OSC 1 keeps the session name readable.
+ *
  * Pass `null` to opt out — the hook becomes a no-op and leaves the
  * terminal title untouched.
  *
  * On Windows, uses `process.title` (classic conhost doesn't support OSC).
- * Elsewhere, writes OSC 0 (set title+icon) via Ink's stdout.
  */
-export function useTerminalTitle(title: string | null): void {
+export function useTerminalTitle(title: string | TerminalTitlePair | null): void {
   const writeRaw = useContext(TerminalWriteContext)
 
   useEffect(() => {
@@ -23,12 +28,34 @@ export function useTerminalTitle(title: string | null): void {
       return
     }
 
-    const clean = stripAnsi(title)
-
     if (process.platform === 'win32') {
+      const clean = stripAnsi(typeof title === 'string' ? title : title.window ?? title.tab ?? '')
       process.title = clean
-    } else {
-      writeRaw(osc(OSC.SET_TITLE_AND_ICON, clean))
+      return
+    }
+
+    if (typeof title === 'string') {
+      writeRaw(osc(OSC.SET_TITLE_AND_ICON, stripAnsi(title)))
+      return
+    }
+
+    // Separate tab (OSC 1) and window (OSC 2) titles so narrow tab bars
+    // show the short session name instead of a truncated tail.
+    const tab = stripAnsi(title.tab ?? '')
+    const window = stripAnsi(title.window ?? '')
+    if (tab && window) {
+      writeRaw(osc(OSC.SET_ICON, tab) + osc(OSC.SET_TITLE, window))
+    } else if (window) {
+      writeRaw(osc(OSC.SET_TITLE_AND_ICON, window))
+    } else if (tab) {
+      writeRaw(osc(OSC.SET_TITLE_AND_ICON, tab))
     }
   }, [title, writeRaw])
 }
+
+export interface TerminalTitlePair {
+  /** Short title for the tab/icon label (OSC 1). */
+  tab?: string
+  /** Full title for the window title bar (OSC 2). */
+  window?: string
+}

ui-tui/src/app/useMainApp.ts

@@ -626,7 +626,12 @@ export function useMainApp(gw: GatewayClient) {
   const tabCwd = ui.info?.cwd
 
   useTerminalTitle(
-    model ? composeTabTitle(marker, ui.sessionTitle, model, tabCwd ? shortCwd(tabCwd, 24) : '') : 'Hermes'
+    model
+      ? {
+          tab: composeTabTitle(marker, ui.sessionTitle, '', ''),
+          window: composeTabTitle(marker, ui.sessionTitle, model, tabCwd ? shortCwd(tabCwd, 24) : ''),
+        }
+      : 'Hermes'
   )
 
   useEffect(() => {

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

@@ -167,7 +167,11 @@ declare module '@hermes/ink' {
     readonly write: (data: string) => boolean
   }
   export function useTerminalFocus(): boolean
-  export function useTerminalTitle(title: string | null): void
+  export function useTerminalTitle(title: string | TerminalTitlePair | null): void
+  export interface TerminalTitlePair {
+    tab?: string
+    window?: string
+  }
   export function useDeclaredCursor(args: {
     readonly line: number
     readonly column: number