perf(dashboard-popout): bound terminal preview resize work

src/main/ipc/terminal-preview-output-stream.ts

@@ -81,6 +81,9 @@ export class TerminalPreviewOutputStream {
   }
 
   append(data: string, meta?: TerminalPreviewOutputMeta): void {
+    if (this.isDisposed || this.awaitingReconnect || this.resyncPending) {
+      return
+    }
     if (this.bufferingSnapshot) {
       this.appendInitial(data, meta)
     } else {

src/main/ipc/terminal-preview.test.ts

@@ -301,6 +301,29 @@ describe('registerTerminalPreviewHandlers', () => {
     expect(runtime.unsubscribeResize).toHaveBeenCalledTimes(1)
   })
 
+  it('stops batching changed-grid output while an earlier frame drains before resync', async () => {
+    vi.useFakeTimers()
+    const runtime = makeRuntime()
+    registerTerminalPreviewHandlers(runtime as never)
+    const sender = makeSender()
+    await handlers.get('terminalPreview:connect')!(eventFor(sender), { ptyId: 'p1' })
+
+    runtime.listeners[0]!('old')
+    await vi.advanceTimersByTimeAsync(5)
+    runtime.resizeListeners[0]!({ cols: 100, rows: 30 })
+    expect(sender.send).toHaveBeenCalledTimes(1)
+
+    runtime.listeners[0]!('captured by the replacement snapshot')
+    expect(vi.getTimerCount()).toBe(0)
+
+    handlers.get('terminalPreview:ack')!(eventFor(sender), { ptyId: 'p1', bytes: 3 })
+    expect(sender.send).toHaveBeenLastCalledWith('terminalPreview:data', {
+      type: 'resync',
+      ptyId: 'p1'
+    })
+    expect(sender.send).toHaveBeenCalledTimes(2)
+  })
+
   it('claims the PTY grid on fit and reports the size actually in effect', async () => {
     const runtime = makeRuntime()
     runtime.getTerminalSize.mockReturnValue({ cols: 132, rows: 40 })

src/renderer/src/components/dashboard-popout/preview-grid-claim.test.ts

@@ -45,4 +45,38 @@ describe('createPreviewGridClaim', () => {
     expect(fit).toHaveBeenCalledWith('pty-1', 90, 30)
     claim.dispose()
   })
+
+  it('coalesces a continuous resize burst into one settled fit request', async () => {
+    vi.useFakeTimers()
+    const fit = vi.fn(async (_ptyId: string, cols: number, rows: number) => ({ cols, rows }))
+    Object.assign(window, { api: { terminalPreview: { fit } } })
+    const box = document.createElement('div')
+    const container = document.createElement('div')
+    const screen = document.createElement('div')
+    screen.className = 'xterm-screen'
+    box.appendChild(container)
+    container.appendChild(screen)
+    dimension(box, 'clientWidth', 800)
+    dimension(box, 'clientHeight', 480)
+    dimension(screen, 'offsetWidth', 800)
+    dimension(screen, 'offsetHeight', 384)
+    const claim = createPreviewGridClaim({
+      ptyId: 'pty-1',
+      container,
+      getTerminal: () => ({ cols: 80, rows: 24 }) as never
+    })
+
+    claim.schedule()
+    for (let step = 1; step <= 10; step += 1) {
+      await vi.advanceTimersByTimeAsync(100)
+      dimension(box, 'clientWidth', 800 + step * 20)
+      claim.schedule()
+    }
+
+    expect(fit).not.toHaveBeenCalled()
+    await vi.advanceTimersByTimeAsync(200)
+    expect(fit).toHaveBeenCalledTimes(1)
+    expect(fit).toHaveBeenCalledWith('pty-1', 100, 30)
+    claim.dispose()
+  })
 })

src/renderer/src/components/dashboard-popout/preview-grid-claim.ts

@@ -70,9 +70,12 @@ export function createPreviewGridClaim(args: {
   }
 
   const schedule = (): void => {
-    if (timer || disposed) {
+    if (disposed) {
       return
     }
+    if (timer) {
+      clearTimeout(timer)
+    }
     timer = setTimeout(() => {
       timer = null
       request()