fix(terminal): send mode 2031 replies immediately

src/renderer/src/components/terminal-pane/terminal-appearance.test.ts

@@ -6,10 +6,10 @@ import {
   applyTerminalAppearance,
   hexToRgba,
   installMode2031Handlers,
-  maybePushMode2031Flip,
-  mode2031SequenceFor,
   publishTerminalViewAttributesAtAppStart
 } from './terminal-appearance'
+import { maybePushMode2031Flip } from './terminal-mode-2031-replies'
+import { mode2031SequenceFor } from '../../../../shared/terminal-color-scheme-protocol'
 import { replayIntoTerminal, type ReplayingPanesRef } from './replay-guard'
 import { _resetTerminalViewAttributesPublisherForTest } from './terminal-view-attributes-publisher'
 import type { TerminalViewAttributes } from '../../../../shared/terminal-view-attributes'
@@ -17,12 +17,14 @@ import type { TerminalViewAttributes } from '../../../../shared/terminal-view-at
 function fakeTransport(overrides?: { connected?: boolean; sendOk?: boolean }): {
   isConnected: () => boolean
   sendInput: ReturnType<typeof vi.fn<(data: string) => boolean>>
+  sendInputImmediate: ReturnType<typeof vi.fn<(data: string) => boolean>>
 } {
   const connected = overrides?.connected ?? true
   const sendOk = overrides?.sendOk ?? true
   return {
     isConnected: () => connected,
-    sendInput: vi.fn<(data: string) => boolean>(() => sendOk)
+    sendInput: vi.fn<(data: string) => boolean>(() => sendOk),
+    sendInputImmediate: vi.fn<(data: string) => boolean>(() => sendOk)
   }
 }
 
@@ -42,7 +44,7 @@ describe('maybePushMode2031Flip', () => {
     const pushed = maybePushMode2031Flip(1, 'dark', transport, subs, last)
 
     expect(pushed).toBe(false)
-    expect(transport.sendInput).not.toHaveBeenCalled()
+    expect(transport.sendInputImmediate).not.toHaveBeenCalled()
     expect(last.has(1)).toBe(false)
   })
 
@@ -54,8 +56,9 @@ describe('maybePushMode2031Flip', () => {
     const pushed = maybePushMode2031Flip(1, 'dark', transport, subs, last)
 
     expect(pushed).toBe(true)
-    expect(transport.sendInput).toHaveBeenCalledTimes(1)
-    expect(transport.sendInput).toHaveBeenCalledWith('\x1b[?997;1n')
+    expect(transport.sendInputImmediate).toHaveBeenCalledTimes(1)
+    expect(transport.sendInputImmediate).toHaveBeenCalledWith('\x1b[?997;1n')
+    expect(transport.sendInput).not.toHaveBeenCalled()
     expect(last.get(1)).toBe('dark')
   })
 
@@ -70,7 +73,7 @@ describe('maybePushMode2031Flip', () => {
     maybePushMode2031Flip(1, 'dark', transport, subs, last)
     maybePushMode2031Flip(1, 'dark', transport, subs, last)
 
-    expect(transport.sendInput).toHaveBeenCalledTimes(1)
+    expect(transport.sendInputImmediate).toHaveBeenCalledTimes(1)
     expect(last.get(1)).toBe('dark')
   })
 
@@ -83,7 +86,7 @@ describe('maybePushMode2031Flip', () => {
     maybePushMode2031Flip(1, 'light', transport, subs, last)
     maybePushMode2031Flip(1, 'dark', transport, subs, last)
 
-    expect(transport.sendInput.mock.calls.map((c) => c[0])).toEqual([
+    expect(transport.sendInputImmediate.mock.calls.map((c) => c[0])).toEqual([
       '\x1b[?997;1n',
       '\x1b[?997;2n',
       '\x1b[?997;1n'
@@ -99,11 +102,11 @@ describe('maybePushMode2031Flip', () => {
     const pushed = maybePushMode2031Flip(1, 'dark', transport, subs, last)
 
     expect(pushed).toBe(false)
-    expect(transport.sendInput).not.toHaveBeenCalled()
+    expect(transport.sendInputImmediate).not.toHaveBeenCalled()
     expect(last.has(1)).toBe(false)
   })
 
-  it('leaves last-mode untouched when sendInput reports failure', () => {
+  it('leaves last-mode untouched when immediate input reports failure', () => {
     // So a reconnect / retry will re-emit on the next appearance pass.
     const transport = fakeTransport({ sendOk: false })
     const subs = new Map([[1, true]])
@@ -112,7 +115,7 @@ describe('maybePushMode2031Flip', () => {
     const pushed = maybePushMode2031Flip(1, 'dark', transport, subs, last)
 
     expect(pushed).toBe(false)
-    expect(transport.sendInput).toHaveBeenCalledTimes(1)
+    expect(transport.sendInputImmediate).toHaveBeenCalledTimes(1)
     expect(last.has(1)).toBe(false)
   })
 
@@ -130,8 +133,8 @@ describe('maybePushMode2031Flip', () => {
     maybePushMode2031Flip(1, 'dark', transportA, subs, last) // suppressed
     maybePushMode2031Flip(2, 'dark', transportB, subs, last) // flip
 
-    expect(transportA.sendInput).toHaveBeenCalledTimes(1)
-    expect(transportB.sendInput).toHaveBeenCalledTimes(2)
+    expect(transportA.sendInputImmediate).toHaveBeenCalledTimes(1)
+    expect(transportB.sendInputImmediate).toHaveBeenCalledTimes(2)
     expect(last.get(1)).toBe('dark')
     expect(last.get(2)).toBe('dark')
   })

src/renderer/src/components/terminal-pane/terminal-appearance.ts

@@ -1,7 +1,6 @@
 import type { IDisposable, IParser, ITheme } from '@xterm/xterm'
 import type { PaneManager } from '@/lib/pane-manager/pane-manager'
 import type { GlobalSettings } from '../../../../shared/types'
-import { mode2031SequenceFor } from '../../../../shared/terminal-color-scheme-protocol'
 import { resolveTerminalFontWeights } from '../../../../shared/terminal-fonts'
 import { resolveTerminalLigaturesEnabled } from '../../../../shared/terminal-ligatures'
 import {
@@ -24,8 +23,7 @@ import { HEX_COLOR_RE } from '../../../../shared/color-validation'
 import type { TerminalViewAttributes } from '../../../../shared/terminal-view-attributes'
 import { publishTerminalViewAttributes } from './terminal-view-attributes-publisher'
 import { normalizeTerminalLineHeight } from '../../../../shared/terminal-line-height-settings'
-
-export { mode2031SequenceFor }
+import { maybePushMode2031Flip } from './terminal-mode-2031-replies'
 
 // Why Pick<IParser, ...> over a hand-rolled structural type: keeps the helper
 // tied to xterm's canonical signature so any upstream tightening (added
@@ -112,33 +110,6 @@ export function installMode2031Handlers(deps: Mode2031HandlerDeps): IDisposable[
   ]
 }
 
-// Gate on actual mode flip so font/size/opacity tweaks — which also re-run
-// applyTerminalAppearance — don't spam subscribed TUIs with CSI 997. The
-// subscribe/last-mode maps are mutated in place so callers share state with
-// the lifecycle hook's seed path.
-export function maybePushMode2031Flip(
-  paneId: number,
-  mode: 'dark' | 'light',
-  transport: Pick<PtyTransport, 'isConnected' | 'sendInput'>,
-  paneMode2031: Map<number, boolean>,
-  paneLastThemeMode: Map<number, 'dark' | 'light'>
-): boolean {
-  if (!transport.isConnected()) {
-    return false
-  }
-  if (!paneMode2031.get(paneId)) {
-    return false
-  }
-  if (paneLastThemeMode.get(paneId) === mode) {
-    return false
-  }
-  if (!transport.sendInput(mode2031SequenceFor(mode))) {
-    return false
-  }
-  paneLastThemeMode.set(paneId, mode)
-  return true
-}
-
 export function hexToRgba(hex: string, alpha: number): string {
   let clean = hex.replace('#', '')
   if (clean.length === 3) {

src/renderer/src/components/terminal-pane/terminal-mode-2031-replies.test.ts

@@ -0,0 +1,68 @@
+import { describe, expect, it, vi } from 'vitest'
+import { pushMode2031SeedReply } from './terminal-mode-2031-replies'
+
+describe('pushMode2031SeedReply', () => {
+  function createHarness(connected: boolean): {
+    connected: { current: boolean }
+    subscribed: { current: boolean }
+    sendInput: ReturnType<typeof vi.fn<(data: string) => boolean>>
+    sendInputImmediate: ReturnType<typeof vi.fn<(data: string) => boolean>>
+    scheduled: (() => void)[]
+    recordMode: ReturnType<typeof vi.fn>
+    push: () => void
+  } {
+    const connectedState = { current: connected }
+    const subscribed = { current: true }
+    const sendInput = vi.fn<(data: string) => boolean>(() => true)
+    const sendInputImmediate = vi.fn<(data: string) => boolean>(() => true)
+    const scheduled: (() => void)[] = []
+    const recordMode = vi.fn()
+    const transport = {
+      isConnected: () => connectedState.current,
+      sendInput,
+      sendInputImmediate
+    }
+    return {
+      connected: connectedState,
+      subscribed,
+      sendInput,
+      sendInputImmediate,
+      scheduled,
+      recordMode,
+      push: () =>
+        pushMode2031SeedReply(1, {
+          hasPane: () => true,
+          isSubscribed: () => subscribed.current,
+          getTransport: () => transport,
+          getMode: () => 'dark',
+          recordMode,
+          schedule: (callback) => scheduled.push(callback)
+        })
+    }
+  }
+
+  it('routes the DSR response through latency-critical input', () => {
+    const harness = createHarness(true)
+
+    harness.push()
+
+    expect(harness.sendInputImmediate).toHaveBeenCalledWith('\x1b[?997;1n')
+    expect(harness.sendInput).not.toHaveBeenCalled()
+    expect(harness.recordMode).toHaveBeenCalledWith(1, 'dark')
+  })
+
+  it('cancels a pre-connect retry after the program unsubscribes', () => {
+    const harness = createHarness(false)
+
+    harness.push()
+    expect(harness.scheduled).toHaveLength(1)
+
+    harness.subscribed.current = false
+    harness.connected.current = true
+    harness.scheduled.shift()?.()
+
+    expect(harness.sendInputImmediate).not.toHaveBeenCalled()
+    expect(harness.sendInput).not.toHaveBeenCalled()
+    expect(harness.scheduled).toHaveLength(0)
+  })
+})

src/renderer/src/components/terminal-pane/terminal-mode-2031-replies.ts

@@ -0,0 +1,75 @@
+import { mode2031SequenceFor } from '../../../../shared/terminal-color-scheme-protocol'
+import type { TerminalColorSchemeMode } from '../../../../shared/terminal-color-scheme-protocol'
+import type { PtyTransport } from './pty-transport'
+
+const MODE_2031_CONNECT_RETRY_MS = 25
+const MODE_2031_CONNECT_ATTEMPTS = 8
+
+type Mode2031ReplyTransport = Pick<PtyTransport, 'isConnected' | 'sendInputImmediate'>
+
+type Mode2031SeedReplyDeps = {
+  hasPane: (paneId: number) => boolean
+  isSubscribed: (paneId: number) => boolean
+  getTransport: (paneId: number) => Mode2031ReplyTransport | undefined
+  getMode: () => TerminalColorSchemeMode | null
+  recordMode: (paneId: number, mode: TerminalColorSchemeMode) => void
+  schedule: (callback: () => void, delayMs: number) => void
+}
+
+function sendMode2031Reply(
+  transport: Mode2031ReplyTransport,
+  mode: TerminalColorSchemeMode
+): boolean {
+  // Why: fish stops reading mode-2031 replies quickly; remote input batching
+  // can otherwise deliver this terminal response after the shell regains input.
+  return transport.sendInputImmediate(mode2031SequenceFor(mode))
+}
+
+export function pushMode2031SeedReply(paneId: number, deps: Mode2031SeedReplyDeps): void {
+  let attempts = 0
+  const send = (): void => {
+    // Why: a TUI can unsubscribe while the PTY is connecting; every delayed
+    // attempt must revalidate intent or its DSR reply can land at a shell prompt.
+    if (!deps.hasPane(paneId) || !deps.isSubscribed(paneId)) {
+      return
+    }
+    const transport = deps.getTransport(paneId)
+    if (!transport?.isConnected()) {
+      attempts += 1
+      if (attempts < MODE_2031_CONNECT_ATTEMPTS) {
+        deps.schedule(send, MODE_2031_CONNECT_RETRY_MS)
+      }
+      return
+    }
+    const mode = deps.getMode()
+    if (mode && sendMode2031Reply(transport, mode)) {
+      deps.recordMode(paneId, mode)
+    }
+  }
+  send()
+}
+
+// Appearance updates include font and opacity changes, so only report actual
+// color-mode flips to programs that still have mode 2031 enabled.
+export function maybePushMode2031Flip(
+  paneId: number,
+  mode: TerminalColorSchemeMode,
+  transport: Mode2031ReplyTransport,
+  paneMode2031: Map<number, boolean>,
+  paneLastThemeMode: Map<number, TerminalColorSchemeMode>
+): boolean {
+  if (!transport.isConnected()) {
+    return false
+  }
+  if (!paneMode2031.get(paneId)) {
+    return false
+  }
+  if (paneLastThemeMode.get(paneId) === mode) {
+    return false
+  }
+  if (!sendMode2031Reply(transport, mode)) {
+    return false
+  }
+  paneLastThemeMode.set(paneId, mode)
+  return true
+}

src/renderer/src/components/terminal-pane/use-terminal-pane-lifecycle.ts

@@ -58,11 +58,8 @@ import {
 import { resolveTerminalLayoutActiveLeafId } from './terminal-layout-leaf-ids'
 import { makePaneKey } from '../../../../shared/stable-pane-id'
 import { applyExpandedLayoutTo, restoreExpandedLayoutFrom } from './expand-collapse'
-import {
-  applyTerminalAppearance,
-  installMode2031Handlers,
-  mode2031SequenceFor
-} from './terminal-appearance'
+import { applyTerminalAppearance, installMode2031Handlers } from './terminal-appearance'
+import { pushMode2031SeedReply } from './terminal-mode-2031-replies'
 import { handleOsc52ClipboardRequest } from './osc52-clipboard'
 import { showOsc52ClipboardBlockedToast } from './osc52-clipboard-blocked-toast'
 import { parseOsc7 } from './parse-osc7'
@@ -604,34 +601,22 @@ export function useTerminalPaneLifecycle({
   }
 
   const pushMode2031ForPane = (paneId: number): void => {
-    let attempts = 0
-    const send = (): void => {
-      if (!managerRef.current?.getPanes().some((pane) => pane.id === paneId)) {
-        return
+    pushMode2031SeedReply(paneId, {
+      hasPane: (candidateId) =>
+        managerRef.current?.getPanes().some((pane) => pane.id === candidateId) === true,
+      isSubscribed: (candidateId) => paneMode2031Ref.current.get(candidateId) === true,
+      getTransport: (candidateId) => paneTransportsRef.current.get(candidateId),
+      getMode: () => {
+        const currentSettings = settingsRef.current
+        return currentSettings
+          ? resolveEffectiveTerminalAppearance(currentSettings, systemPrefersDarkRef.current).mode
+          : null
+      },
+      recordMode: (candidateId, mode) => paneLastThemeModeRef.current.set(candidateId, mode),
+      schedule: (callback, delayMs) => {
+        window.setTimeout(callback, delayMs)
       }
-      const transport = paneTransportsRef.current.get(paneId)
-      if (!transport?.isConnected()) {
-        // Why: TUIs can subscribe before pty:spawn resolves. Retry briefly so
-        // the recorded subscription still receives the initial dark/light seed.
-        attempts += 1
-        if (attempts < 8) {
-          window.setTimeout(send, 25)
-        }
-        return
-      }
-      const currentSettings = settingsRef.current
-      if (!currentSettings) {
-        return
-      }
-      const { mode } = resolveEffectiveTerminalAppearance(
-        currentSettings,
-        systemPrefersDarkRef.current
-      )
-      if (transport.sendInput(mode2031SequenceFor(mode))) {
-        paneLastThemeModeRef.current.set(paneId, mode)
-      }
-    }
-    send()
+    })
   }
 
   // Initialize PaneManager instance once