fix: reduce Gemini terminal flashing (#203)

src/renderer/src/components/terminal-pane/pty-connection.ts

@@ -1,4 +1,5 @@
 import type { PaneManager, ManagedPane } from '@/lib/pane-manager/pane-manager'
+import { isGeminiTerminalTitle } from '@/lib/agent-status'
 import type { PtyTransport } from './pty-transport'
 import { createIpcPtyTransport } from './pty-transport'
 
@@ -23,6 +24,7 @@ export function connectPanePty(
 ): void {
   const onExit = (ptyId: string): void => {
     deps.clearTabPtyId(deps.tabId, ptyId)
+    manager.setPaneGpuRendering(pane.id, true)
     const panes = manager.getPanes()
     if (panes.length <= 1) {
       deps.onPtyExitRef.current(ptyId)
@@ -31,7 +33,8 @@ export function connectPanePty(
     manager.closePane(pane.id)
   }
 
-  const onTitleChange = (title: string): void => {
+  const onTitleChange = (title: string, rawTitle: string): void => {
+    manager.setPaneGpuRendering(pane.id, !isGeminiTerminalTitle(rawTitle))
     deps.updateTabTitle(deps.tabId, title)
   }
 

src/renderer/src/components/terminal-pane/pty-transport.ts

@@ -1,7 +1,8 @@
 import {
   detectAgentStatusFromTitle,
   clearWorkingIndicators,
-  createAgentStatusTracker
+  createAgentStatusTracker,
+  normalizeTerminalTitle
 } from '@/lib/agent-status'
 
 export type PtyTransport = {
@@ -65,7 +66,7 @@ export function extractLastOscTitle(data: string): string | null {
 export type IpcPtyTransportOptions = {
   cwd?: string
   onPtyExit?: (ptyId: string) => void
-  onTitleChange?: (title: string) => void
+  onTitleChange?: (title: string, rawTitle: string) => void
   onPtySpawn?: (ptyId: string) => void
   onBell?: () => void
   onAgentBecameIdle?: () => void
@@ -132,8 +133,8 @@ export function createIpcPtyTransport(opts: IpcPtyTransportOptions = {}): PtyTra
                 clearTimeout(staleTitleTimer)
                 staleTitleTimer = null
               }
-              lastEmittedTitle = title
-              onTitleChange(title)
+              lastEmittedTitle = normalizeTerminalTitle(title)
+              onTitleChange(lastEmittedTitle, title)
               agentTracker?.handleTitle(title)
             } else if (
               lastEmittedTitle &&
@@ -152,7 +153,7 @@ export function createIpcPtyTransport(opts: IpcPtyTransportOptions = {}): PtyTra
                 ) {
                   const cleared = clearWorkingIndicators(lastEmittedTitle)
                   lastEmittedTitle = cleared
-                  onTitleChange(cleared)
+                  onTitleChange(cleared, cleared)
                 }
               }, STALE_TITLE_TIMEOUT)
             }

src/renderer/src/lib/agent-status.test.ts

@@ -2,7 +2,9 @@ import { describe, expect, it, vi } from 'vitest'
 import {
   detectAgentStatusFromTitle,
   clearWorkingIndicators,
-  createAgentStatusTracker
+  createAgentStatusTracker,
+  isGeminiTerminalTitle,
+  normalizeTerminalTitle
 } from './agent-status'
 import { extractLastOscTitle } from '../components/terminal-pane/pty-transport'
 
@@ -188,6 +190,36 @@ describe('clearWorkingIndicators', () => {
   })
 })
 
+describe('normalizeTerminalTitle', () => {
+  it('collapses Gemini working titles to a stable label', () => {
+    expect(normalizeTerminalTitle('✦  Typing prompt... (workspace)')).toBe('✦ Gemini CLI')
+    expect(normalizeTerminalTitle('⏲  Working… (workspace)')).toBe('✦ Gemini CLI')
+  })
+
+  it('collapses Gemini idle and permission titles to stable labels', () => {
+    expect(normalizeTerminalTitle('◇  Ready (workspace)')).toBe('◇ Gemini CLI')
+    expect(normalizeTerminalTitle('✋  Action Required (workspace)')).toBe('✋ Gemini CLI')
+  })
+
+  it('leaves non-Gemini titles unchanged', () => {
+    expect(normalizeTerminalTitle('⠂ Claude Code')).toBe('⠂ Claude Code')
+    expect(normalizeTerminalTitle('bash')).toBe('bash')
+  })
+})
+
+describe('isGeminiTerminalTitle', () => {
+  it('detects Gemini titles by symbol or name', () => {
+    expect(isGeminiTerminalTitle('✦  Typing prompt... (workspace)')).toBe(true)
+    expect(isGeminiTerminalTitle('◇  Ready (workspace)')).toBe(true)
+    expect(isGeminiTerminalTitle('gemini waiting for input')).toBe(true)
+  })
+
+  it('does not match other terminal titles', () => {
+    expect(isGeminiTerminalTitle('⠂ Claude Code')).toBe(false)
+    expect(isGeminiTerminalTitle('bash')).toBe(false)
+  })
+})
+
 describe('createAgentStatusTracker', () => {
   // --- Claude Code: real captured OSC title sequence (v2.1.86) ---
   // CRITICAL: Claude Code changes the title to the TASK DESCRIPTION,

src/renderer/src/lib/agent-status.ts

@@ -9,6 +9,16 @@ const GEMINI_PERMISSION = '\u270B' // ✋
 
 const AGENT_NAMES = ['claude', 'codex', 'gemini', 'opencode', 'aider']
 
+export function isGeminiTerminalTitle(title: string): boolean {
+  return (
+    title.includes(GEMINI_PERMISSION) ||
+    title.includes(GEMINI_WORKING) ||
+    title.includes(GEMINI_SILENT_WORKING) ||
+    title.includes(GEMINI_IDLE) ||
+    title.toLowerCase().includes('gemini')
+  )
+}
+
 function containsBrailleSpinner(title: string): boolean {
   for (const char of title) {
     const codePoint = char.codePointAt(0)
@@ -89,6 +99,32 @@ export function createAgentStatusTracker(onBecameIdle: () => void): {
   }
 }
 
+/**
+ * Normalize high-churn agent titles into stable display labels before storing
+ * them in app state. Gemini CLI can emit per-keystroke title updates, which
+ * otherwise causes broad rerenders and visible flashing.
+ */
+export function normalizeTerminalTitle(title: string): string {
+  if (!title) {
+    return title
+  }
+
+  if (isGeminiTerminalTitle(title)) {
+    const status = detectAgentStatusFromTitle(title)
+    if (status === 'permission') {
+      return `${GEMINI_PERMISSION} Gemini CLI`
+    }
+    if (status === 'working') {
+      return `${GEMINI_WORKING} Gemini CLI`
+    }
+    if (status === 'idle') {
+      return `${GEMINI_IDLE} Gemini CLI`
+    }
+  }
+
+  return title
+}
+
 export function detectAgentStatusFromTitle(title: string): AgentStatus | null {
   if (!title) {
     return null

src/renderer/src/lib/pane-manager/pane-lifecycle.ts

@@ -17,6 +17,7 @@ import { safeFit } from './pane-tree-ops'
 // ---------------------------------------------------------------------------
 
 const TERMINAL_PADDING = 4
+const ENABLE_WEBGL_RENDERER = true
 
 export function createPaneDOM(
   id: number,
@@ -102,6 +103,7 @@ export function createPaneDOM(
     container,
     xtermContainer,
     linkTooltip,
+    gpuRenderingEnabled: ENABLE_WEBGL_RENDERER,
     fitAddon,
     searchAddon,
     unicode11Addon,
@@ -146,8 +148,9 @@ export function openTerminal(pane: ManagedPaneInternal): void {
   // Activate unicode 11
   terminal.unicode.activeVersion = '11'
 
-  // Attach GPU renderer
-  attachWebgl(pane)
+  if (pane.gpuRenderingEnabled) {
+    attachWebgl(pane)
+  }
 
   // Initial fit (deferred to ensure layout has settled)
   requestAnimationFrame(() => {
@@ -156,6 +159,10 @@ export function openTerminal(pane: ManagedPaneInternal): void {
 }
 
 export function attachWebgl(pane: ManagedPaneInternal): void {
+  if (!ENABLE_WEBGL_RENDERER || !pane.gpuRenderingEnabled) {
+    pane.webglAddon = null
+    return
+  }
   try {
     const webglAddon = new WebglAddon()
     webglAddon.onContextLoss(() => {

src/renderer/src/lib/pane-manager/pane-manager-types.ts

@@ -43,6 +43,7 @@ export type ManagedPane = {
 export type ManagedPaneInternal = {
   xtermContainer: HTMLElement
   linkTooltip: HTMLElement
+  gpuRenderingEnabled: boolean
   webglAddon: WebglAddon | null
   unicode11Addon: Unicode11Addon
   webLinksAddon: WebLinksAddon

src/renderer/src/lib/pane-manager/pane-manager.ts

@@ -209,6 +209,32 @@ export class PaneManager {
     applyRootBackground(this.root, this.styleOptions)
   }
 
+  setPaneGpuRendering(paneId: number, enabled: boolean): void {
+    const pane = this.panes.get(paneId)
+    if (!pane) {
+      return
+    }
+
+    pane.gpuRenderingEnabled = enabled
+
+    if (!enabled) {
+      if (pane.webglAddon) {
+        try {
+          pane.webglAddon.dispose()
+        } catch {
+          /* ignore */
+        }
+        pane.webglAddon = null
+      }
+      return
+    }
+
+    if (!pane.webglAddon) {
+      attachWebgl(pane)
+      safeFit(pane)
+    }
+  }
+
   /**
    * Suspend GPU rendering for all panes. Disposes WebGL addons to free
    * GPU contexts while keeping Terminal instances alive (scrollback, cursor,
@@ -233,7 +259,7 @@ export class PaneManager {
    */
   resumeRendering(): void {
     for (const pane of this.panes.values()) {
-      if (!pane.webglAddon) {
+      if (pane.gpuRenderingEnabled && !pane.webglAddon) {
         attachWebgl(pane)
       }
     }

src/renderer/src/store/slices/terminals.ts

@@ -150,11 +150,18 @@ export const createTerminalSlice: StateCreator<AppState, [], [], TerminalSlice>
 
   updateTabTitle: (tabId, title) => {
     set((s) => {
+      let changed = false
       const next = { ...s.tabsByWorktree }
       for (const wId of Object.keys(next)) {
-        next[wId] = next[wId].map((t) => (t.id === tabId ? { ...t, title } : t))
+        next[wId] = next[wId].map((t) => {
+          if (t.id !== tabId || t.title === title) {
+            return t
+          }
+          changed = true
+          return { ...t, title }
+        })
       }
-      return { tabsByWorktree: next }
+      return changed ? { tabsByWorktree: next } : s
     })
   },