Reduce terminal renderer delivery pressure

src/main/ipc/pty.test.ts

@@ -4372,7 +4372,7 @@ describe('registerPtyHandlers', () => {
       for (let index = 0; index < 400; index++) {
         vi.advanceTimersByTime(1)
       }
-      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(512)
+      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(128)
       expect(vi.getTimerCount()).toBe(0)
 
       writeListener(null, {
@@ -4381,8 +4381,8 @@ describe('registerPtyHandlers', () => {
       })
       interactiveProc.emitData('\x1b[20;2Hredraw')
 
-      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(513)
-      expect(mainWindow.webContents.send).toHaveBeenNthCalledWith(513, 'pty:data', {
+      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(129)
+      expect(mainWindow.webContents.send).toHaveBeenNthCalledWith(129, 'pty:data', {
         id: interactiveSpawn.id,
         data: '\x1b[20;2Hredraw'
       })
@@ -4396,14 +4396,14 @@ describe('registerPtyHandlers', () => {
         })
         interactiveProc.emitData(reserveChunk)
       }
-      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(529)
+      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(145)
 
       writeListener(null, {
         id: interactiveSpawn.id,
         data: 'a'
       })
       interactiveProc.emitData(reserveChunk)
-      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(529)
+      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(145)
     } finally {
       vi.useRealTimers()
     }
@@ -4439,11 +4439,11 @@ describe('registerPtyHandlers', () => {
         vi.advanceTimersByTime(1)
       }
 
-      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(512)
+      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(128)
       ackData(null, { id: spawns[0].id, charCount: 16 * 1024 })
       vi.advanceTimersByTime(1)
 
-      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(513)
+      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(129)
     } finally {
       vi.useRealTimers()
     }
@@ -4479,22 +4479,22 @@ describe('registerPtyHandlers', () => {
       for (let index = 0; index < 400; index++) {
         vi.advanceTimersByTime(1)
       }
-      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(512)
+      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(128)
 
       const activeIndex = procs.length - 1
       procs[activeIndex]!.emitData('active-output')
       setActiveRendererPty(null, { id: spawns[activeIndex]!.id, active: true })
       vi.advanceTimersByTime(8)
 
-      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(513)
-      expect(mainWindow.webContents.send).toHaveBeenNthCalledWith(513, 'pty:data', {
+      expect(mainWindow.webContents.send).toHaveBeenCalledTimes(129)
+      expect(mainWindow.webContents.send).toHaveBeenNthCalledWith(129, 'pty:data', {
         id: spawns[activeIndex]!.id,
         data: 'active-output'
       })
       expect(getPtyRendererDeliveryDebugSnapshot()).toMatchObject({
         activeRendererPtyCount: 1,
         pendingPtyCount: procs.length - 1,
-        rendererInFlightChars: 8 * 1024 * 1024 + 'active-output'.length
+        rendererInFlightChars: 2 * 1024 * 1024 + 'active-output'.length
       })
       ackData(null, { id: spawns[0]!.id, charCount: 16 * 1024 })
     } finally {

src/main/ipc/pty.ts

@@ -1071,7 +1071,7 @@ export function registerPtyHandlers(
   const PTY_BATCH_FLUSH_CHUNK_CHARS = 16 * 1024
   const PTY_BATCH_FLUSH_MAX_WRITES = 2
   const PTY_RENDERER_IN_FLIGHT_HIGH_WATER_CHARS = 512 * 1024
-  const PTY_RENDERER_TOTAL_IN_FLIGHT_HIGH_WATER_CHARS = 8 * 1024 * 1024
+  const PTY_RENDERER_TOTAL_IN_FLIGHT_HIGH_WATER_CHARS = 2 * 1024 * 1024
   const PTY_RENDERER_INTERACTIVE_RESERVE_CHARS = 256 * 1024
   // Why: active panes need a bounded lane through old hidden bulk output so a
   // keystroke redraw can reach the renderer before every background ACK lands.

tests/e2e/artificial-opencode-hidden-pressure-scenario.ts

@@ -72,6 +72,8 @@ type HiddenPressureAckGate = {
   heldAckChars: number
 }
 
+const MAIN_RENDERER_PRESSURE_TARGET_CHARS = 2 * 1024 * 1024
+
 export function pressureOutputScript(runId: string): string {
   return `
 const paneIndex = process.argv[2] ?? '0'
@@ -196,7 +198,9 @@ export async function runHiddenRealPtyPressureScenario<
     expect(debug?.hiddenRendererSkippedChars ?? 0).toBeGreaterThan(0)
     expect(pressureBeforeTyping.peakPendingChars).toBeGreaterThan(0)
     expect(pressureBeforeTyping.ackGatedFlushSkipCount).toBeGreaterThan(0)
-    expect(mainPressure?.peakRendererInFlightChars ?? 0).toBeGreaterThanOrEqual(8 * 1024 * 1024)
+    expect(mainPressure?.peakRendererInFlightChars ?? 0).toBeGreaterThanOrEqual(
+      MAIN_RENDERER_PRESSURE_TARGET_CHARS
+    )
     expect(ackGate?.heldAckChars ?? 0).toBeGreaterThan(0)
     expect(measurement.medianLatencyMs).toBeLessThan(75)
     expect(measurement.worstLatencyMs).toBeLessThan(300)

tests/e2e/artificial-opencode-main-pressure-scenario.ts

@@ -40,6 +40,7 @@ type MainPressureSchedulerSnapshot = {
 }
 
 const MAX_RENDERER_SCHEDULER_QUEUED_CHARS = 2 * 1024 * 1024
+const MAIN_RENDERER_PRESSURE_TARGET_CHARS = 2 * 1024 * 1024
 
 type MainPressureDeps<
   TMeasurement,
@@ -270,7 +271,9 @@ function expectMainPressureAndTyping<TMeasurement extends MainPressureMeasuremen
 }): void {
   expect(pressureBeforeTyping.peakPendingChars).toBeGreaterThan(0)
   expect(pressureBeforeTyping.ackGatedFlushSkipCount).toBeGreaterThan(0)
-  expect(mainPressure?.peakRendererInFlightChars ?? 0).toBeGreaterThanOrEqual(8 * 1024 * 1024)
+  expect(mainPressure?.peakRendererInFlightChars ?? 0).toBeGreaterThanOrEqual(
+    MAIN_RENDERER_PRESSURE_TARGET_CHARS
+  )
   expect(ackGate?.heldAckChars ?? 0).toBeGreaterThan(0)
   expect(scheduler?.droppedBacklogCount ?? Number.POSITIVE_INFINITY).toBe(0)
   expect(scheduler?.peakQueuedChars ?? Number.POSITIVE_INFINITY).toBeLessThanOrEqual(

tests/e2e/artificial-opencode-terminal-load.spec.ts

@@ -111,6 +111,7 @@ const HIDDEN_PRESSURE_START_DELAY_MS = 1200
 const DEFAULT_FRAME_COUNT = 180
 const DEFAULT_FRAME_INTERVAL_MS = 6
 const TIMER_SAMPLE_MS = 16
+const MAIN_RENDERER_PRESSURE_TARGET_CHARS = 2 * 1024 * 1024
 // Why: these are regression budgets, not observed baselines. Repeated local
 // 100-pane OpenCode-scale runs are below 50ms worst-key latency; keep enough
 // CI headroom while still failing changes that make typing visibly sluggish.
@@ -385,7 +386,7 @@ async function waitForMainPtyPressureBacklog(page: Page): Promise<MainPtyPressur
       async () => {
         lastSnapshot = await readMainPtyPressureDebug(page)
         return (
-          (lastSnapshot?.peakRendererInFlightChars ?? 0) >= 8 * 1024 * 1024 &&
+          (lastSnapshot?.peakRendererInFlightChars ?? 0) >= MAIN_RENDERER_PRESSURE_TARGET_CHARS &&
           (lastSnapshot?.peakPendingChars ?? 0) > 0 &&
           (lastSnapshot?.ackGatedFlushSkipCount ?? 0) > 0
         )