diff --git a/config/reliability-gates.jsonc b/config/reliability-gates.jsonc
index 2785645d621..01db646c217 100644
--- a/config/reliability-gates.jsonc
+++ b/config/reliability-gates.jsonc
@@ -3048,6 +3048,105 @@
       ],
       "demotionRule": "Demote or quarantine if the unit gate flakes without a product bug or harness bug filed to the owner."
     },
+    {
+      "id": "terminal-scroll.streaming-refocus-intent",
+      "title": "Streaming refocus preserves follow-output viewport intent",
+      "maturity": "experimental",
+      "protection": "partial",
+      "owner": "terminal-rendering",
+      "layer": "renderer-unit-and-electron-e2e",
+      "surfaces": [
+        "terminal lifecycle",
+        "window focus recovery",
+        "hidden-to-visible resume",
+        "xterm write backlog",
+        "scrollback"
+      ],
+      "platforms": ["macos", "linux", "windows"],
+      "providers": ["local", "daemon", "ssh", "wsl", "remote-runtime"],
+      "coveredPlatforms": ["macos"],
+      "coveredProviders": ["local", "daemon"],
+      "coverageNotes": "Unit coverage proves provider-independent ordering for any PaneManager. Live Electron coverage exercises a local PTY through the daemon on macOS; SSH, WSL, remote-runtime, Linux, and Windows remain unproved for this exact race.",
+      "motivatingLinks": [
+        "https://github.com/stablyai/orca/issues/11753",
+        "https://github.com/stablyai/orca/pull/11915"
+      ],
+      "invariant": "When output is queued during a focus or visibility transition, Orca records the pre-flush viewport intent before xterm parses backlog writes, so a follow-output terminal stays at the bottom and a pinned terminal keeps its prior position.",
+      "oracle": "Unit tests require exactly one intent sync before each queued-output flush. The Electron test injects a transient top-of-buffer xterm wobble during refocus and requires every presented scrollbar frame, including the final rendered output, to remain at the bottom.",
+      "commands": [
+        "pnpm exec vitest run --config config/vitest.config.ts src/renderer/src/components/terminal-pane/terminal-visibility-resume.test.ts",
+        "pnpm exec electron-vite build --mode e2e",
+        "SKIP_BUILD=1 pnpm exec playwright test tests/e2e/terminal-streaming-refocus-viewport.spec.ts --config tests/playwright.config.ts --project electron-headless --workers=1 --repeat-each=5"
+      ],
+      "testFiles": [
+        "src/renderer/src/components/terminal-pane/terminal-visibility-resume.test.ts",
+        "tests/e2e/terminal-streaming-refocus-viewport.spec.ts"
+      ],
+      "assertionRefs": [
+        {
+          "file": "src/renderer/src/components/terminal-pane/terminal-visibility-resume.test.ts",
+          "assertions": [
+            "window-wake recovery synchronizes viewport intent exactly once before flushing queued output",
+            "heavy visibility resume synchronizes intent exactly once before flushing queued output"
+          ]
+        },
+        {
+          "file": "tests/e2e/terminal-streaming-refocus-viewport.spec.ts",
+          "assertions": [
+            "phase-one scrollback is visibly ready at the bottom without a fixed sleep",
+            "no presented animation frame moves the scrollbar thumb away from the bottom during refocus",
+            "the final streamed marker renders with the visible scrollbar still at the bottom"
+          ]
+        }
+      ],
+      "evidenceRuns": [
+        {
+          "date": "2026-08-01",
+          "runner": "local",
+          "platform": "macos",
+          "command": "pnpm exec vitest run --config config/vitest.config.ts src/renderer/src/components/terminal-pane/terminal-visibility-resume.test.ts",
+          "result": "passed",
+          "durationSeconds": 0.096,
+          "summary": "14 tests passed, including exact sync count and pre-flush ordering for wake and heavy visibility resume."
+        },
+        {
+          "date": "2026-08-01",
+          "runner": "local",
+          "platform": "macos",
+          "command": "SKIP_BUILD=1 pnpm exec playwright test tests/e2e/terminal-streaming-refocus-viewport.spec.ts --config tests/playwright.config.ts --project electron-headless --workers=1 --repeat-each=5",
+          "result": "passed",
+          "durationSeconds": 35.2,
+          "summary": "Five consecutive Electron iterations passed after replacing fixed-time readiness and stale tab capture with deterministic viewport and pane-identity oracles."
+        }
+      ],
+      "runtimeBudget": {
+        "p95Seconds": 30,
+        "scope": "focused renderer unit test or one Electron E2E iteration"
+      },
+      "flakeHistory": {
+        "status": "soaking",
+        "evidence": "Five consecutive local Electron iterations passed; CI soak history is still required before promotion."
+      },
+      "redGreenEvidence": {
+        "status": "complete",
+        "evidence": "The controlled xterm viewport wobble reproduces the pinned-top failure with post-flush intent sampling and passes when intent is latched before the queued write flush."
+      },
+      "performanceBudget": {
+        "required": true,
+        "evidence": "Wake recovery keeps one O(panes) intent pass before the existing bounded 64 KiB-per-pane flush. Heavy resume removes its second intent pass and keeps the existing bounded 256 KiB-per-pane flush; no polling, timers, subprocesses, IPC, output parsing, fit, or repaint work is added."
+      },
+      "promotionCriteria": [
+        "Collect stable CI soak history for the Electron race gate.",
+        "Run the live oracle on Linux and Windows terminal backends.",
+        "Add live SSH or remote-runtime coverage for queued output during refocus."
+      ],
+      "knownGaps": [
+        "The deterministic wobble uses xterm private buffer state and must be updated if that internal contract changes.",
+        "Live Linux, Windows, SSH, WSL, and remote-runtime execution is not covered for this exact race.",
+        "The Electron gate proves follow-output behavior; adjacent scroll-intent coverage protects pinned viewport behavior."
+      ],
+      "demotionRule": "Demote or quarantine if the Electron oracle flakes without a product bug or harness bug filed to terminal-rendering."
+    },
     {
       "id": "startup-upgrade.persisted-session-corpus",
       "title": "Current Orca preserves or recovers old production persisted sessions",
diff --git a/electron.vite.config.ts b/electron.vite.config.ts
index 02239421ae9..39f923cb215 100644
--- a/electron.vite.config.ts
+++ b/electron.vite.config.ts
@@ -206,6 +206,8 @@ export const electronViteConfig: UserConfig = {
         external: isExternalMainModule,
         input: {
           index: resolve('src/main/index.ts'),
+          // Why: sandboxed webview preloads cannot load Rollup helper chunks.
+          'browser-window-close-preload': resolve('src/preload/browser-window-close.ts'),
           'daemon-entry': resolve('src/main/daemon/daemon-entry.ts'),
           'plugin-host-entry': resolve('src/main/plugins/plugin-host-entry.ts'),
           'computer-sidecar': resolve('src/main/computer/sidecar-entry.ts'),
diff --git a/src/main/browser/browser-manager.test.ts b/src/main/browser/browser-manager.test.ts
index 286f172a645..b93a0358537 100644
--- a/src/main/browser/browser-manager.test.ts
+++ b/src/main/browser/browser-manager.test.ts
@@ -1512,6 +1512,38 @@ describe('browserManager', () => {
     expect(browserManager.getGuestWebContentsId('browser-destroyed-before-register')).toBeNull()
   })
 
+  it('removes a destroyed primary guest from its tab registration maps', () => {
+    const guest = {
+      id: 306,
+      isDestroyed: vi.fn(() => false),
+      getType: vi.fn(() => 'webview'),
+      setBackgroundThrottling: guestSetBackgroundThrottlingMock,
+      setWindowOpenHandler: guestSetWindowOpenHandlerMock,
+      on: guestOnMock,
+      off: guestOffMock,
+      openDevTools: guestOpenDevToolsMock
+    }
+    webContentsFromIdMock.mockReturnValue(guest)
+
+    browserManager.attachGuestPolicies(guest as never)
+    browserManager.registerGuest({
+      browserPageId: 'browser-destroyed-after-register',
+      webContentsId: guest.id,
+      rendererWebContentsId
+    })
+
+    const destroyedHandler = guestOnMock.mock.calls.find(
+      ([event]) => event === 'destroyed'
+    )?.[1] as (() => void) | undefined
+    destroyedHandler?.()
+
+    expect(browserManager.getGuestWebContentsId('browser-destroyed-after-register')).toBeNull()
+    const managerState = browserManager as unknown as {
+      tabIdByWebContentsId: Map<number, string>
+    }
+    expect(managerState.tabIdByWebContentsId.has(guest.id)).toBe(false)
+  })
+
   it('fully unregisters stale guests discovered during authorization', () => {
     const guest = {
       id: 305,
diff --git a/src/main/browser/browser-manager.ts b/src/main/browser/browser-manager.ts
index 7dafca617f2..66f6ac653bf 100644
--- a/src/main/browser/browser-manager.ts
+++ b/src/main/browser/browser-manager.ts
@@ -640,7 +640,6 @@ export class BrowserManager {
 
     // Why: bot detectors probe APIs that differ in Electron webviews; inject overrides each load so manual browsing passes.
     const disposeAntiDetection = this.injectAntiDetection(guest)
-
     // Why: disable throttling so background screenshots still get frames; else the compositor stalls and capture returns empty.
     guest.setBackgroundThrottling(false)
     const installClickedLinkRouting = (): void => {
@@ -940,11 +939,15 @@ export class BrowserManager {
   private retireStaleGuestWebContents(previousWebContentsId: number): void {
     // Why: after a renderer-process swap, stop the dead guest id resolving to the live page so stale callbacks don't hit the wrong session.
     this.cleanupGuestPolicyAttachment(previousWebContentsId)
-    this.tabIdByWebContentsId.delete(previousWebContentsId)
   }
 
   private cleanupGuestPolicyAttachment(guestWebContentsId: number): void {
-    const isPrimaryGuest = this.tabIdByWebContentsId.has(guestWebContentsId)
+    const browserTabId = this.tabIdByWebContentsId.get(guestWebContentsId)
+    const isPrimaryGuest = browserTabId !== undefined
+    if (browserTabId && this.webContentsIdByTabId.get(browserTabId) === guestWebContentsId) {
+      this.webContentsIdByTabId.delete(browserTabId)
+    }
+    this.tabIdByWebContentsId.delete(guestWebContentsId)
     this.certificateTrustController?.onGuestRetired(guestWebContentsId)
     const policyCleanup = this.policyCleanupByGuestId.get(guestWebContentsId)
     if (policyCleanup) {
diff --git a/src/main/persistence-async-write-syscalls.test.ts b/src/main/persistence-async-write-syscalls.test.ts
new file mode 100644
index 00000000000..6a4491e8b38
--- /dev/null
+++ b/src/main/persistence-async-write-syscalls.test.ts
@@ -0,0 +1,496 @@
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest'
+import { mkdtempSync, readFileSync, readdirSync, rmSync, utimesSync, writeFileSync } from 'node:fs'
+import type * as NodeFs from 'node:fs'
+import type * as NodeFsPromises from 'node:fs/promises'
+import { join } from 'node:path'
+import { tmpdir } from 'node:os'
+
+const testState = { dir: '' }
+
+const fsCalls = vi.hoisted(() => {
+  const blocker = new Int32Array(new SharedArrayBuffer(4))
+  const calls = {
+    recording: false,
+    dirPrefix: '',
+    /** When > 0, every recorded sync call parks the main thread this long — a stalled mount in miniature. */
+    stallMs: 0,
+    syncCalls: [] as string[],
+    asyncCalls: [] as string[],
+    failAsync: null as ((fn: string, target: string) => NodeJS.ErrnoException | null) | null,
+    beforeAsync: null as ((fn: string, target: string) => void) | null,
+    waitAsync: null as ((fn: string, target: string) => Promise<void> | null) | null,
+    reset(): void {
+      calls.syncCalls.length = 0
+      calls.asyncCalls.length = 0
+      calls.stallMs = 0
+      calls.failAsync = null
+      calls.beforeAsync = null
+      calls.waitAsync = null
+    },
+    inScope(target: unknown): target is string {
+      return (
+        calls.recording &&
+        typeof target === 'string' &&
+        calls.dirPrefix !== '' &&
+        target.startsWith(calls.dirPrefix)
+      )
+    },
+    recordSync(fn: string, target: unknown): void {
+      if (!calls.inScope(target)) {
+        return
+      }
+      calls.syncCalls.push(`${fn}:${target}`)
+      if (calls.stallMs > 0) {
+        // Atomics.wait blocks the thread the way an uninterruptible syscall does.
+        Atomics.wait(blocker, 0, 0, calls.stallMs)
+      }
+    },
+    recordAsync(fn: string, target: unknown): NodeJS.ErrnoException | null {
+      if (!calls.inScope(target)) {
+        return null
+      }
+      calls.asyncCalls.push(`${fn}:${target}`)
+      calls.beforeAsync?.(fn, target)
+      return calls.failAsync?.(fn, target) ?? null
+    }
+  }
+  return calls
+})
+
+vi.mock('node:fs', async (importOriginal) => {
+  const actual = await importOriginal<typeof NodeFs>()
+  const patched: Record<string, unknown> = { ...actual }
+  for (const name of Object.keys(actual)) {
+    const original = (actual as unknown as Record<string, unknown>)[name]
+    if (!name.endsWith('Sync') || typeof original !== 'function') {
+      continue
+    }
+    const fn = original as (...args: unknown[]) => unknown
+    const wrapper = (...args: unknown[]): unknown => {
+      fsCalls.recordSync(name, args[0])
+      return fn(...args)
+    }
+    patched[name] = Object.assign(wrapper, fn)
+  }
+  return { ...patched, default: patched }
+})
+
+vi.mock('node:fs/promises', async (importOriginal) => {
+  const actual = await importOriginal<typeof NodeFsPromises>()
+  const patched: Record<string, unknown> = { ...actual }
+  for (const name of ['stat', 'access', 'rename', 'copyFile', 'rm', 'mkdir', 'open']) {
+    const fn = (actual as unknown as Record<string, (...args: unknown[]) => unknown>)[name]
+    patched[name] = async (...args: unknown[]): Promise<unknown> => {
+      const failure = fsCalls.recordAsync(name, args[0])
+      if (failure) {
+        throw failure
+      }
+      if (typeof args[0] === 'string') {
+        await fsCalls.waitAsync?.(name, args[0])
+      }
+      return fn(...args)
+    }
+  }
+  return { ...patched, default: patched }
+})
+
+vi.mock('./ssh/ssh-config-parser', () => ({
+  loadUserSshConfig: vi.fn(),
+  sshConfigHostsToTargets: vi.fn()
+}))
+
+vi.mock('./telemetry/client', () => ({ track: vi.fn() }))
+
+vi.mock('./telemetry/cohort-classifier', () => ({
+  getCohortAtEmit: vi.fn().mockReturnValue({ nth_repo_added: 2 })
+}))
+
+// Deterministic cipher so two stores driven through identical mutations produce identical bytes.
+vi.mock('electron', () => ({
+  app: { getPath: () => testState.dir },
+  safeStorage: {
+    isEncryptionAvailable: () => true,
+    encryptString: (plaintext: string) => Buffer.from(`enc:${plaintext}`, 'utf-8'),
+    decryptString: (ciphertext: Buffer) => ciphertext.toString('utf-8').slice('enc:'.length)
+  }
+}))
+
+const BACKUP_COUNT = 5
+const BACKUP_MIN_INTERVAL_MS = 60 * 60 * 1000
+const PAST_ROTATION_INTERVAL_MS = BACKUP_MIN_INTERVAL_MS * 2
+const SAVE_DEBOUNCE_MS = 1_000
+
+const ROTATION_INTERLEAVE_CASES = [
+  ['initial access', 'access', ''],
+  ['oldest removal', 'rm', '.bak.4'],
+  ['slot access', 'access', '.bak.0'],
+  ['slot rename', 'rename', '.bak.0'],
+  ['final copy', 'copyFile', '']
+] as const
+
+type TestStore = {
+  updateUI(updates: { sidebarWidth: number }): void
+  waitForPendingWrite(): Promise<void>
+  flushOrThrow(): void
+}
+
+async function createStore(dir: string): Promise<TestStore> {
+  testState.dir = dir
+  vi.resetModules()
+  const { Store, initDataPath } = await import('./persistence')
+  initDataPath()
+  return new Store() as unknown as TestStore
+}
+
+function dataFile(dir: string): string {
+  return join(dir, 'orca-data.json')
+}
+
+function seedStaleBackup(dir: string): void {
+  const path = `${dataFile(dir)}.bak.0`
+  writeFileSync(path, '{"stale":true}', 'utf-8')
+  const staleSeconds = (Date.now() - PAST_ROTATION_INTERVAL_MS) / 1000
+  utimesSync(path, staleSeconds, staleSeconds)
+}
+
+function ringSnapshot(dir: string): Record<string, string> {
+  const snapshot: Record<string, string> = {}
+  for (const name of readdirSync(dir).sort()) {
+    if (name === 'orca-data.json' || name.startsWith('orca-data.json.bak.')) {
+      snapshot[name] = readFileSync(join(dir, name), 'utf-8')
+    }
+  }
+  return snapshot
+}
+
+describe('async persistence write path avoids synchronous fs syscalls', () => {
+  const dirs: string[] = []
+
+  function makeDir(): string {
+    const dir = mkdtempSync(join(tmpdir(), 'orca-async-write-'))
+    dirs.push(dir)
+    return dir
+  }
+
+  beforeEach(() => {
+    fsCalls.recording = false
+    fsCalls.dirPrefix = ''
+    fsCalls.reset()
+    vi.useFakeTimers()
+  })
+
+  afterEach(() => {
+    fsCalls.recording = false
+    vi.useRealTimers()
+    while (dirs.length > 0) {
+      rmSync(dirs.pop() as string, { recursive: true, force: true })
+    }
+  })
+
+  async function recordAsyncSave(
+    store: TestStore,
+    dir: string,
+    sidebarWidth: number
+  ): Promise<void> {
+    store.updateUI({ sidebarWidth })
+    fsCalls.dirPrefix = dir
+    fsCalls.recording = true
+    try {
+      vi.advanceTimersByTime(PAST_ROTATION_INTERVAL_MS)
+      await store.waitForPendingWrite()
+    } finally {
+      fsCalls.recording = false
+    }
+  }
+
+  it('issues no sync fs syscall under the profile dir when rotation runs with an empty ring', async () => {
+    const dir = makeDir()
+    const store = await createStore(dir)
+
+    await recordAsyncSave(store, dir, 301)
+
+    expect(fsCalls.syncCalls).toEqual([])
+    // Rotation must actually have happened, else the assertion above is vacuous.
+    expect(ringSnapshot(dir)['orca-data.json.bak.0']).toBe(readFileSync(dataFile(dir), 'utf-8'))
+  })
+
+  it('uses an awaited stat, not statSync, for the backup rotation interval check', async () => {
+    const dir = makeDir()
+    const store = await createStore(dir)
+    seedStaleBackup(dir)
+
+    await recordAsyncSave(store, dir, 302)
+
+    expect(fsCalls.syncCalls).toEqual([])
+    expect(fsCalls.asyncCalls).toContain(`stat:${dataFile(dir)}.bak.0`)
+  })
+
+  it('issues no sync fs syscall while rotating a saturated ring', async () => {
+    const dir = makeDir()
+    const store = await createStore(dir)
+
+    // One more save than the ring holds, so the oldest slot is evicted and every slot renames.
+    for (let i = 0; i <= BACKUP_COUNT; i++) {
+      await recordAsyncSave(store, dir, 310 + i)
+    }
+
+    expect(fsCalls.syncCalls).toEqual([])
+    const ring = ringSnapshot(dir)
+    expect(Object.keys(ring)).toContain(`orca-data.json.bak.${BACKUP_COUNT - 1}`)
+    expect(Object.keys(ring)).not.toContain(`orca-data.json.bak.${BACKUP_COUNT}`)
+  })
+
+  it('lets a main-thread timer keep firing while a rotating save is in flight', async () => {
+    // A recorded sync call stalls long enough for the heartbeat to catch it.
+    vi.useRealTimers()
+    const dir = makeDir()
+    const store = await createStore(dir)
+    seedStaleBackup(dir)
+    // Generous stall so ordinary scheduler/GC jitter can't reach the threshold on a loaded CI box.
+    const stallMs = 500
+
+    let lastTick = Date.now()
+    let worstGapMs = 0
+    const heartbeat = setInterval(() => {
+      const now = Date.now()
+      worstGapMs = Math.max(worstGapMs, now - lastTick)
+      lastTick = now
+    }, 10)
+
+    try {
+      store.updateUI({ sidebarWidth: 341 })
+      fsCalls.dirPrefix = dir
+      fsCalls.stallMs = stallMs
+      fsCalls.recording = true
+      lastTick = Date.now()
+      await new Promise((resolve) => setTimeout(resolve, SAVE_DEBOUNCE_MS + 200))
+      await store.waitForPendingWrite()
+    } finally {
+      fsCalls.recording = false
+      clearInterval(heartbeat)
+    }
+
+    expect(worstGapMs).toBeLessThan(stallMs)
+    // The save really happened, so a small gap isn't just an absent write.
+    expect(ringSnapshot(dir)['orca-data.json.bak.0']).toBe(readFileSync(dataFile(dir), 'utf-8'))
+  }, 20_000)
+
+  it('skips rotation when a sync flush rotated during the rotation-interval await', async () => {
+    // The acquired owner keeps rotation when the flush skips the ring.
+    const dir = makeDir()
+    const store = await createStore(dir)
+    seedStaleBackup(dir)
+    const staleBackup = readFileSync(`${dataFile(dir)}.bak.0`, 'utf-8')
+
+    store.updateUI({ sidebarWidth: 361 })
+    fsCalls.dirPrefix = dir
+    fsCalls.recording = true
+    let flushed = false
+    fsCalls.beforeAsync = (fn, target) => {
+      if (flushed || fn !== 'stat' || !target.endsWith('.bak.0')) {
+        return
+      }
+      flushed = true
+      store.updateUI({ sidebarWidth: 362 })
+      store.flushOrThrow()
+    }
+    try {
+      vi.advanceTimersByTime(PAST_ROTATION_INTERVAL_MS)
+      await store.waitForPendingWrite()
+    } finally {
+      fsCalls.recording = false
+      fsCalls.beforeAsync = null
+    }
+
+    expect(flushed).toBe(true)
+    const ring = ringSnapshot(dir)
+    expect(ring['orca-data.json.bak.0']).toBe(ring['orca-data.json'])
+    expect(ring['orca-data.json.bak.1']).toBe(staleBackup)
+    expect(ring['orca-data.json.bak.2']).toBeUndefined()
+  })
+
+  it('keeps the due check inside ownership when a second writer starts', async () => {
+    const dir = makeDir()
+    const store = await createStore(dir)
+    seedStaleBackup(dir)
+    const almostDueSeconds = (Date.now() - (BACKUP_MIN_INTERVAL_MS - SAVE_DEBOUNCE_MS - 100)) / 1000
+    utimesSync(`${dataFile(dir)}.bak.0`, almostDueSeconds, almostDueSeconds)
+    const staleBackup = readFileSync(`${dataFile(dir)}.bak.0`, 'utf-8')
+    const statCall = `stat:${dataFile(dir)}.bak.0`
+    let releaseRotation!: () => void
+    const rotationRelease = new Promise<void>((resolve) => {
+      releaseRotation = resolve
+    })
+    let signalRotation!: () => void
+    const rotationStarted = new Promise<void>((resolve) => {
+      signalRotation = resolve
+    })
+    let held = false
+    fsCalls.waitAsync = (fn, target) => {
+      if (held || fn !== 'stat' || target !== `${dataFile(dir)}.bak.0`) {
+        return null
+      }
+      held = true
+      signalRotation()
+      return rotationRelease
+    }
+
+    fsCalls.dirPrefix = dir
+    fsCalls.recording = true
+    store.updateUI({ sidebarWidth: 371 })
+    vi.advanceTimersByTime(SAVE_DEBOUNCE_MS)
+    const firstWrite = store.waitForPendingWrite()
+    try {
+      await rotationStarted
+      store.updateUI({ sidebarWidth: 372 })
+      store.flushOrThrow()
+      store.updateUI({ sidebarWidth: 373 })
+      vi.advanceTimersByTime(SAVE_DEBOUNCE_MS)
+      await store.waitForPendingWrite()
+      expect(fsCalls.asyncCalls.filter((call) => call === statCall)).toHaveLength(1)
+    } finally {
+      releaseRotation()
+      await firstWrite
+      fsCalls.recording = false
+      fsCalls.waitAsync = null
+    }
+    const ring = ringSnapshot(dir)
+    expect(ring['orca-data.json.bak.0']).toBe(ring['orca-data.json'])
+    expect(ring['orca-data.json.bak.1']).toBe(staleBackup)
+    expect(ring['orca-data.json.bak.2']).toBeUndefined()
+  })
+
+  it.each(ROTATION_INTERLEAVE_CASES)(
+    'keeps one rotation owner when a sync flush lands during %s',
+    async (_phase, expectedFn, targetSuffix) => {
+      const dir = makeDir()
+      const store = await createStore(dir)
+      seedStaleBackup(dir)
+      const staleBackup = readFileSync(`${dataFile(dir)}.bak.0`, 'utf-8')
+      const expectedTarget = `${dataFile(dir)}${targetSuffix}`
+
+      store.updateUI({ sidebarWidth: 363 })
+      fsCalls.dirPrefix = dir
+      fsCalls.recording = true
+      let flushed = false
+      fsCalls.beforeAsync = (fn, target) => {
+        if (flushed || fn !== expectedFn || target !== expectedTarget) {
+          return
+        }
+        flushed = true
+        store.updateUI({ sidebarWidth: 364 })
+        store.flushOrThrow()
+      }
+      try {
+        vi.advanceTimersByTime(PAST_ROTATION_INTERVAL_MS)
+        await store.waitForPendingWrite()
+      } finally {
+        fsCalls.recording = false
+        fsCalls.beforeAsync = null
+      }
+
+      expect(flushed).toBe(true)
+      const ring = ringSnapshot(dir)
+      expect(ring['orca-data.json.bak.0']).toBe(ring['orca-data.json'])
+      expect(ring['orca-data.json.bak.1']).toBe(staleBackup)
+      expect(ring['orca-data.json.bak.2']).toBeUndefined()
+    }
+  )
+
+  it('does not log for absent ring slots even when the mount rejects renames non-ENOENT', async () => {
+    // Probing keeps degraded mounts from logging one error per absent slot.
+    const dir = makeDir()
+    const store = await createStore(dir)
+    const errors = vi.spyOn(console, 'error').mockImplementation(() => {})
+    fsCalls.failAsync = (fn, target) =>
+      fn === 'rename' && target.includes('.bak.')
+        ? Object.assign(new Error('stale NFS file handle'), { code: 'ESTALE' })
+        : null
+
+    try {
+      await recordAsyncSave(store, dir, 351)
+      expect(errors).not.toHaveBeenCalled()
+    } finally {
+      errors.mockRestore()
+    }
+  })
+
+  it('logs when a ring slot that exists fails to rotate', async () => {
+    const dir = makeDir()
+    const store = await createStore(dir)
+    seedStaleBackup(dir)
+    const errors = vi.spyOn(console, 'error').mockImplementation(() => {})
+    fsCalls.failAsync = (fn, target) =>
+      fn === 'rename' && target.endsWith('.bak.0')
+        ? Object.assign(new Error('permission denied'), { code: 'EPERM' })
+        : null
+
+    try {
+      await recordAsyncSave(store, dir, 352)
+      expect(errors).toHaveBeenCalledWith(
+        '[persistence] Failed to rotate backup',
+        `${dataFile(dir)}.bak.0`,
+        '->',
+        `${dataFile(dir)}.bak.1`,
+        expect.objectContaining({ code: 'EPERM' })
+      )
+    } finally {
+      errors.mockRestore()
+    }
+  })
+
+  it('produces a .bak ring byte-identical to the sync path, at capacity and with ring holes', async () => {
+    const asyncDir = makeDir()
+    const syncDir = makeDir()
+    // Match generated IDs so only rotation behavior can differ.
+    const seedDir = makeDir()
+    const seedStore = await createStore(seedDir)
+    seedStore.updateUI({ sidebarWidth: 320 })
+    seedStore.flushOrThrow()
+    const seed = readFileSync(dataFile(seedDir), 'utf-8')
+    for (const dir of [asyncDir, syncDir]) {
+      writeFileSync(dataFile(dir), seed, 'utf-8')
+      // Holes: slots 1 and 3 occupied, 0 and 2 missing — exercises the per-slot existence branch.
+      writeFileSync(`${dataFile(dir)}.bak.1`, '{"old":1}', 'utf-8')
+      writeFileSync(`${dataFile(dir)}.bak.3`, '{"old":3}', 'utf-8')
+    }
+
+    const widths = [321, 322, 323, 324, 325, 326]
+    const asyncStore = await createStore(asyncDir)
+    for (const width of widths) {
+      asyncStore.updateUI({ sidebarWidth: width })
+      vi.advanceTimersByTime(PAST_ROTATION_INTERVAL_MS)
+      await asyncStore.waitForPendingWrite()
+    }
+
+    const syncStore = await createStore(syncDir)
+    for (const width of widths) {
+      syncStore.updateUI({ sidebarWidth: width })
+      syncStore.flushOrThrow()
+      vi.advanceTimersByTime(PAST_ROTATION_INTERVAL_MS)
+    }
+
+    const ring = ringSnapshot(asyncDir)
+    expect(ring).toEqual(ringSnapshot(syncDir))
+    expect(Object.keys(ring)).toContain(`orca-data.json.bak.${BACKUP_COUNT - 1}`)
+  })
+
+  it('keeps the sync quit/crash fallback on synchronous syscalls', async () => {
+    const dir = makeDir()
+    const store = await createStore(dir)
+    seedStaleBackup(dir)
+
+    store.updateUI({ sidebarWidth: 331 })
+    fsCalls.dirPrefix = dir
+    fsCalls.recording = true
+    try {
+      store.flushOrThrow()
+    } finally {
+      fsCalls.recording = false
+    }
+
+    expect(fsCalls.syncCalls).toContain(`statSync:${dataFile(dir)}.bak.0`)
+    expect(fsCalls.syncCalls).toContain(`existsSync:${dataFile(dir)}`)
+    expect(fsCalls.asyncCalls).toEqual([])
+  })
+})
diff --git a/src/main/persistence.ts b/src/main/persistence.ts
index c5e4c2a81a9..e5744973f12 100644
--- a/src/main/persistence.ts
+++ b/src/main/persistence.ts
@@ -11,7 +11,7 @@ import {
   statSync,
   realpathSync
 } from 'node:fs'
-import { rename, mkdir, rm, copyFile, open } from 'node:fs/promises'
+import { rename, mkdir, rm, copyFile, open, stat, access } from 'node:fs/promises'
 import { renameDurable, writeFileDurableSync } from './durable-file-write'
 import { join, dirname, isAbsolute, resolve, sep } from 'node:path'
 import { homedir } from 'node:os'
@@ -589,6 +589,14 @@ function backupPath(dataFile: string, index: number): string {
   return `${dataFile}.bak.${index}`
 }
 
+/** existsSync's non-blocking twin: existsSync is an access(F_OK) probe, so access() is the exact analogue. */
+async function exists(path: string): Promise<boolean> {
+  return access(path).then(
+    () => true,
+    () => false
+  )
+}
+
 function buildWorkspaceDirHistoryForUpdate(
   current: GlobalSettings,
   updates: Partial<GlobalSettings>
@@ -2742,6 +2750,8 @@ export class Store {
   private writeTimer: ReturnType<typeof setTimeout> | null = null
   private pendingWrite: Promise<void> | null = null
   private writeGeneration = 0
+  // Prevent a sync flush from interleaving a second rotation with awaited ring mutations.
+  private backupRotationInFlight = false
   // Why: after a profile transfer rewrites this file on disk, a late flush of stale in-memory state would resurrect the moved project.
   private writesFrozen = false
   // Content hash at last write, to skip no-op writes; derived from the payload with encrypted blobs normalized back to plaintext (see buildStateToSave), since encrypt() uses a random IV per call.
@@ -2884,28 +2894,52 @@ export class Store {
     }
   }
 
+  // Why separate from the sync twin: a statSync here parks the Electron main thread in uninterruptible
+  // sleep on a stalled SMB/NFS profile mount. Error semantics are deliberately identical: rotate.
+  private async shouldRotateBackupsAsync(dataFile: string): Promise<boolean> {
+    try {
+      const mtime = (await stat(backupPath(dataFile, 0))).mtimeMs
+      return Date.now() - mtime >= BACKUP_MIN_INTERVAL_MS
+    } catch {
+      return true
+    }
+  }
+
   // Why: rotate current file into the .bak ring so load() can recover if a later primary write is truncated or corrupt.
   private async rotateBackupsAsync(dataFile: string): Promise<void> {
-    if (!existsSync(dataFile)) {
+    if (this.backupRotationInFlight) {
       return
     }
-    await rm(backupPath(dataFile, BACKUP_COUNT - 1)).catch((err: unknown) => {
-      if (err && (err as NodeJS.ErrnoException).code !== 'ENOENT') {
-        console.error('[persistence] Failed to remove oldest backup:', err)
+    this.backupRotationInFlight = true
+    try {
+      if (!(await this.shouldRotateBackupsAsync(dataFile))) {
+        return
       }
-    })
-    for (let i = BACKUP_COUNT - 2; i >= 0; i--) {
-      const src = backupPath(dataFile, i)
-      const dst = backupPath(dataFile, i + 1)
-      if (existsSync(src)) {
-        await rename(src, dst).catch((err) => {
-          console.error('[persistence] Failed to rotate backup', src, '->', dst, err)
-        })
+      if (!(await exists(dataFile))) {
+        return
       }
+      await rm(backupPath(dataFile, BACKUP_COUNT - 1)).catch((err: unknown) => {
+        if (err && (err as NodeJS.ErrnoException).code !== 'ENOENT') {
+          console.error('[persistence] Failed to remove oldest backup:', err)
+        }
+      })
+      for (let i = BACKUP_COUNT - 2; i >= 0; i--) {
+        const src = backupPath(dataFile, i)
+        const dst = backupPath(dataFile, i + 1)
+        // Why probe instead of rename-then-swallow-ENOENT: a degraded mount rejects a rename of an
+        // absent slot with ESTALE/EIO, which would log once per empty slot on every debounced save.
+        if (await exists(src)) {
+          await rename(src, dst).catch((err) => {
+            console.error('[persistence] Failed to rotate backup', src, '->', dst, err)
+          })
+        }
+      }
+      await copyFile(dataFile, backupPath(dataFile, 0)).catch((err) => {
+        console.error('[persistence] Failed to snapshot current file to .bak.0:', err)
+      })
+    } finally {
+      this.backupRotationInFlight = false
     }
-    await copyFile(dataFile, backupPath(dataFile, 0)).catch((err) => {
-      console.error('[persistence] Failed to snapshot current file to .bak.0:', err)
-    })
   }
 
   private rotateBackupsSync(dataFile: string): void {
@@ -3886,18 +3920,15 @@ export class Store {
         await rm(tmpFile).catch(() => {})
       }
     }
-    // Why (issue #1158): rotate backups only after rename succeeded, and let a concurrent flush own rotation.
+    // Why (#1158): rotate only after the primary rename while this write still owns its generation.
     if (this.writeGeneration !== gen) {
       return
     }
-    const now = Date.now()
-    if (this.shouldRotateBackups(now, dataFile)) {
-      await this.rotateBackupsAsync(dataFile)
-    }
+    await this.rotateBackupsAsync(dataFile)
   }
 
   // Why: sync variant only for flush() at shutdown, where the process may exit before an async write completes.
-  private writeToDiskSync(opts: { force?: boolean } = {}): void {
+  private writeToDiskSync(opts: { force?: boolean; skipBackupRotation?: boolean } = {}): void {
     if (this.writesFrozen) {
       return
     }
@@ -3931,7 +3962,7 @@ export class Store {
       }
     }
     const now = Date.now()
-    if (this.shouldRotateBackups(now, dataFile)) {
+    if (!opts.skipBackupRotation && this.shouldRotateBackups(now, dataFile)) {
       this.rotateBackupsSync(dataFile)
     }
   }
@@ -3946,7 +3977,10 @@ export class Store {
     // Why: bump writeGeneration so an in-flight async write skips its rename and can't overwrite this sync write.
     this.writeGeneration++
     this.pendingWrite = null
-    this.writeToDiskSync({ force: asyncWriteWasInFlight })
+    this.writeToDiskSync({
+      force: asyncWriteWasInFlight,
+      skipBackupRotation: this.backupRotationInFlight
+    })
   }
 
   flushActiveViewPreferenceOrThrow(): void {
diff --git a/src/main/ssh/ssh-auth-resolution.ts b/src/main/ssh/ssh-auth-resolution.ts
index 025c8904870..c7e65e26d92 100644
--- a/src/main/ssh/ssh-auth-resolution.ts
+++ b/src/main/ssh/ssh-auth-resolution.ts
@@ -8,18 +8,26 @@ import { isOpenSshConfigBackedTarget } from './system-ssh-args'
 
 // Why: ssh2 only tries keys that are explicitly provided. Users with keys in
 // standard locations (e.g. ~/.ssh/id_ed25519) but no SSH agent running would
-// fail to authenticate. Probing default paths matches VS Code's _findDefaultKeyFile.
+// fail to authenticate. Probe the regular and FIDO2 OpenSSH default paths.
 const DEFAULT_KEY_NAMES = ['id_ed25519', 'id_rsa', 'id_ecdsa', 'id_dsa', 'id_xmss']
+const DEFAULT_SECURITY_KEY_NAMES = ['id_ed25519_sk', 'id_ecdsa_sk']
 
 const DEFAULT_KEY_PATHS = DEFAULT_KEY_NAMES.map((name) => `~/.ssh/${name}`)
+const DEFAULT_IDENTITY_PATHS = [...DEFAULT_KEY_NAMES, ...DEFAULT_SECURITY_KEY_NAMES].map(
+  (name) => `~/.ssh/${name}`
+)
 const WINDOWS_OPENSSH_AGENT_PIPE = '\\\\.\\pipe\\openssh-ssh-agent'
 
 // Why: resolved IdentityFile paths are expanded before auth resolution, so they
 // won't match the ~/... form in DEFAULT_KEY_PATHS.
-const EXPANDED_DEFAULT_KEY_PATHS = DEFAULT_KEY_PATHS.map(resolveSshConfigHomePath)
+const EXPANDED_DEFAULT_KEY_PATHS = DEFAULT_IDENTITY_PATHS.map(resolveSshConfigHomePath)
 
 export type PrivateKeyFile = { path: string; contents: Buffer }
 
+export function listDefaultIdentityFilePaths(): string[] {
+  return [...DEFAULT_IDENTITY_PATHS]
+}
+
 export function findDefaultKeyFile(): PrivateKeyFile | undefined {
   for (const keyPath of DEFAULT_KEY_PATHS) {
     const resolved = resolveSshConfigHomePath(keyPath)
@@ -97,7 +105,10 @@ function resolveExplicitPrivateKeyPaths(
   return resolvedIdentities
 }
 
-function resolvePrivateKeyPaths(target: SshTarget, resolved: SshResolvedConfig | null): string[] {
+export function resolveIdentityFilePaths(
+  target: SshTarget,
+  resolved: Pick<SshResolvedConfig, 'identityFile'> | null
+): string[] {
   if (isOpenSshConfigBackedTarget(target) && resolved) {
     return resolved.identityFile
   }
@@ -138,7 +149,7 @@ export function resolvePrivateKeys(
   target: SshTarget,
   resolved: SshResolvedConfig | null
 ): PrivateKeyFile[] {
-  const keyPaths = resolvePrivateKeyPaths(target, resolved)
+  const keyPaths = resolveIdentityFilePaths(target, resolved)
   if (keyPaths.length > 0 || resolved || target.identityFile) {
     return readPrivateKeys(keyPaths)
   }
@@ -174,16 +185,6 @@ export function findEncryptedPrivateKeyPath(keys: PrivateKeyFile[]): string | un
   return undefined
 }
 
-function resolveIdentityFilePaths(target: SshTarget, resolved: SshResolvedConfig | null): string[] {
-  if (isOpenSshConfigBackedTarget(target) && resolved) {
-    return resolved.identityFile
-  }
-  if (target.identityFile) {
-    return [target.identityFile]
-  }
-  return resolved?.identityFile ?? []
-}
-
 export function resolveAgentConfigValue(
   agentSocket: string,
   target: SshTarget,
diff --git a/src/main/ssh/ssh-connection-utils.test.ts b/src/main/ssh/ssh-connection-utils.test.ts
index a5dd743fd43..5e06a9e7386 100644
--- a/src/main/ssh/ssh-connection-utils.test.ts
+++ b/src/main/ssh/ssh-connection-utils.test.ts
@@ -313,7 +313,7 @@ describe('findDefaultKeyFile', () => {
     expect(result!.contents).toEqual(Buffer.from('key-contents'))
   })
 
-  it('probes keys in VS Code order: ed25519, rsa, ecdsa, dsa, xmss', () => {
+  it('probes regular and FIDO2 keys in stable default order', () => {
     const checkedPaths: string[] = []
     mockExistsSync.mockImplementation((path: unknown) => {
       checkedPaths.push(String(path))
@@ -331,6 +331,34 @@ describe('findDefaultKeyFile', () => {
     ])
   })
 
+  it('keeps a regular default ahead of a malformed FIDO2 default', () => {
+    mockExistsSync.mockImplementation((path: unknown) => {
+      return (
+        path === testHomePath('.ssh', 'id_rsa') || path === testHomePath('.ssh', 'id_ed25519_sk')
+      )
+    })
+    mockReadFileSync.mockImplementation((path: unknown) => {
+      if (String(path) === testHomePath('.ssh', 'id_ed25519_sk')) {
+        throw new Error('malformed FIDO2 key')
+      }
+      return Buffer.from('rsa-key')
+    })
+
+    expect(findDefaultKeyFile()).toEqual({
+      path: '~/.ssh/id_rsa',
+      contents: Buffer.from('rsa-key')
+    })
+  })
+
+  it('leaves FIDO2 defaults out of the ssh2 private-key fallback', () => {
+    mockExistsSync.mockImplementation((path: unknown) => {
+      return path === testHomePath('.ssh', 'id_ed25519_sk')
+    })
+
+    expect(findDefaultKeyFile()).toBeUndefined()
+    expect(mockReadFileSync).not.toHaveBeenCalled()
+  })
+
   it('skips unreadable key files and tries next', () => {
     mockExistsSync.mockImplementation((path: unknown) => {
       return path === testHomePath('.ssh', 'id_ed25519') || path === testHomePath('.ssh', 'id_rsa')
diff --git a/src/main/ssh/ssh-connection.test.ts b/src/main/ssh/ssh-connection.test.ts
index b73cc1e1db3..a3bcadf66dc 100644
--- a/src/main/ssh/ssh-connection.test.ts
+++ b/src/main/ssh/ssh-connection.test.ts
@@ -16,6 +16,7 @@ let execBehavior: 'callback' | 'pending' = 'callback'
 let pendingExecCallback: ((err: Error | undefined, channel: unknown) => void) | null = null
 let sftpBehavior: 'callback' | 'pending' = 'callback'
 let pendingSftpCallback: ((err: Error | undefined, channel: unknown) => void) | null = null
+let notifyClientCreated: (() => void) | undefined
 
 type MockSshClient = {
   setNoDelay: ReturnType<typeof vi.fn>
@@ -45,6 +46,8 @@ vi.mock('ssh2', () => {
     lastConnectConfig?: unknown
     constructor() {
       clientInstances.push(this)
+      notifyClientCreated?.()
+      notifyClientCreated = undefined
     }
     on(event: string, handler: (...args: unknown[]) => void) {
       const handlers = eventHandlers?.get(event) ?? new Set<(...args: unknown[]) => void>()
@@ -168,6 +171,10 @@ import {
 } from './ssh-system-fallback'
 import { getRemoteHostPlatform } from './ssh-remote-platform'
 import type { SshTarget } from '../../shared/ssh-types'
+import {
+  createOpenSshPrivateKeyFixture,
+  createOpenSshPublicKeyFixture
+} from './ssh-security-key-identity.test-fixture'
 
 function createTarget(overrides?: Partial<SshTarget>): SshTarget {
   return {
@@ -278,6 +285,7 @@ describe('SshConnection', () => {
     pendingExecCallback = null
     sftpBehavior = 'callback'
     pendingSftpCallback = null
+    notifyClientCreated = undefined
     clientInstances = []
     getOrcaControlSocketPathMock.mockReset()
     getOrcaControlSocketPathMock.mockReturnValue(null)
@@ -462,10 +470,11 @@ describe('SshConnection', () => {
     const callbacks = createCallbacks()
     const conn = new SshConnection(createTarget(), callbacks)
 
+    const clientCreated = new Promise<void>((resolve) => {
+      notifyClientCreated = resolve
+    })
     const connectResult = conn.connect().catch((error: Error) => error)
-    for (let i = 0; i < 5 && clientInstances.length === 0; i++) {
-      await Promise.resolve()
-    }
+    await clientCreated
     expect(clientInstances).toHaveLength(1)
     await conn.disconnect()
 
@@ -485,10 +494,11 @@ describe('SshConnection', () => {
     const callbacks = createCallbacks()
     const conn = new SshConnection(createTarget(), callbacks)
 
+    const clientCreated = new Promise<void>((resolve) => {
+      notifyClientCreated = resolve
+    })
     const connectResult = conn.connect().catch((error: Error) => error)
-    for (let i = 0; i < 5 && clientInstances.length === 0; i++) {
-      await Promise.resolve()
-    }
+    await clientCreated
     expect(clientInstances).toHaveLength(1)
     await conn.disconnect()
 
@@ -1462,6 +1472,47 @@ describe('SshConnection', () => {
     )
   })
 
+  it('uses system SSH before ssh2 parses a security-key private key', async () => {
+    const directory = mkdtempSync(join(tmpdir(), 'orca-security-key-connect-'))
+    const keyPath = join(directory, 'id_ed25519_sk')
+    writeFileSync(
+      keyPath,
+      createOpenSshPrivateKeyFixture(['sk-ssh-ed25519@openssh.com'], { encrypted: true })
+    )
+    const conn = new SshConnection(createTarget({ identityFile: keyPath }), createCallbacks())
+
+    try {
+      await conn.connect()
+
+      expect(conn.getState().status).toBe('connected')
+      expect(conn.usesSystemSshTransport()).toBe(true)
+      expect(clientInstances).toHaveLength(0)
+      expect(spawnSystemSshCommandMock).toHaveBeenCalledTimes(1)
+    } finally {
+      rmSync(directory, { recursive: true })
+    }
+  })
+
+  it('uses system SSH for an agent-backed security-key public identity', async () => {
+    const directory = mkdtempSync(join(tmpdir(), 'orca-security-key-agent-connect-'))
+    const identityPath = join(directory, 'id_ed25519_sk')
+    writeFileSync(
+      `${identityPath}.pub`,
+      createOpenSshPublicKeyFixture('sk-ssh-ed25519@openssh.com')
+    )
+    const conn = new SshConnection(createTarget({ identityFile: identityPath }), createCallbacks())
+
+    try {
+      await conn.connect()
+
+      expect(conn.usesSystemSshTransport()).toBe(true)
+      expect(clientInstances).toHaveLength(0)
+      expect(spawnSystemSshCommandMock).toHaveBeenCalledTimes(1)
+    } finally {
+      rmSync(directory, { recursive: true })
+    }
+  })
+
   it('falls back to system SSH when ssh2 hits a local network policy reachability error', async () => {
     connectBehavior = 'error'
     connectErrorMessage = 'connect EHOSTUNREACH 192.168.0.210:22 - Local (192.168.0.2:52112)'
diff --git a/src/main/ssh/ssh-connection.ts b/src/main/ssh/ssh-connection.ts
index 17f0a382251..37d661587ad 100644
--- a/src/main/ssh/ssh-connection.ts
+++ b/src/main/ssh/ssh-connection.ts
@@ -41,6 +41,10 @@ import {
   type SshConnectionCallbacks
 } from './ssh-connection-utils'
 import { getPassphrasePrivateKeyPath } from './ssh-private-key-authentication'
+import {
+  requiresSystemSshForSecurityKey,
+  shouldUseSystemSshTransport
+} from './ssh-transport-selection'
 import type { RemoteHostPlatform } from './ssh-remote-platform'
 import {
   resolveSftpTransferPathIfMapped,
@@ -636,7 +640,14 @@ export class SshConnection {
     const resolved = await resolveWithSshG(this.target.configHost || this.target.label).catch(
       () => null
     )
-    if (shouldUseSystemSshTransport(this.target, resolved)) {
+    const usesConfiguredSystemTransport = shouldUseSystemSshTransport(this.target, resolved)
+    const requiresSecurityKeyTransport = usesConfiguredSystemTransport
+      ? false
+      : await requiresSystemSshForSecurityKey(this.target, resolved)
+    if (!this.isCurrentConnectAttempt(connectGeneration)) {
+      throw this.createCancelledConnectAttemptError()
+    }
+    if (usesConfiguredSystemTransport || requiresSecurityKeyTransport) {
       await this.doSystemSshProbeWithControlMasterRetry(connectGeneration, resolved)
       return
     }
@@ -1386,24 +1397,4 @@ export class SshConnection {
   }
 }
 
-export function shouldUseSystemSshTransport(
-  target: SshTarget,
-  resolved: Pick<SshResolvedConfig, 'proxyUseFdpass' | 'proxyCommand' | 'proxyJump'> | null
-): boolean {
-  if (isOpenSshConfigBackedTarget(target) && resolved) {
-    return (
-      process.env.ORCA_SSH_FORCE_SYSTEM_TRANSPORT === '1' ||
-      resolved.proxyUseFdpass === true ||
-      resolved.proxyCommand != null ||
-      resolved.proxyJump != null
-    )
-  }
-  return (
-    process.env.ORCA_SSH_FORCE_SYSTEM_TRANSPORT === '1' ||
-    target.proxyCommand != null ||
-    target.jumpHost != null ||
-    resolved?.proxyUseFdpass === true ||
-    resolved?.proxyCommand != null ||
-    resolved?.proxyJump != null
-  )
-}
+export { shouldUseSystemSshTransport } from './ssh-transport-selection'
diff --git a/src/main/ssh/ssh-security-key-identity.test-fixture.ts b/src/main/ssh/ssh-security-key-identity.test-fixture.ts
new file mode 100644
index 00000000000..0a8bcbd58f4
--- /dev/null
+++ b/src/main/ssh/ssh-security-key-identity.test-fixture.ts
@@ -0,0 +1,42 @@
+function encodeUint32(value: number): Buffer {
+  const buffer = Buffer.alloc(4)
+  buffer.writeUInt32BE(value)
+  return buffer
+}
+
+function sshString(value: string | Buffer): Buffer {
+  const contents = typeof value === 'string' ? Buffer.from(value, 'ascii') : value
+  return Buffer.concat([encodeUint32(contents.length), contents])
+}
+
+export function createOpenSshPrivateKeyFixture(
+  keyTypes: string[],
+  options: { encrypted?: boolean; cipher?: string; privateBlock?: Buffer; authTag?: Buffer } = {}
+): Buffer {
+  const cipher = options.cipher ?? (options.encrypted ? 'aes256-ctr' : 'none')
+  const encrypted = cipher !== 'none'
+  const publicKeys = keyTypes.map((keyType) => sshString(sshString(keyType)))
+  const decoded = Buffer.concat([
+    Buffer.from('openssh-key-v1\0', 'ascii'),
+    sshString(cipher),
+    sshString(encrypted ? 'bcrypt' : 'none'),
+    sshString(encrypted ? Buffer.from('fixture-kdf') : Buffer.alloc(0)),
+    encodeUint32(publicKeys.length),
+    ...publicKeys,
+    sshString(options.privateBlock ?? Buffer.from('fixture-private-block')),
+    options.authTag ?? Buffer.alloc(0)
+  ])
+  const encoded =
+    decoded
+      .toString('base64')
+      .match(/.{1,70}/g)
+      ?.join('\n') ?? ''
+  return Buffer.from(
+    `-----BEGIN OPENSSH PRIVATE KEY-----\n${encoded}\n-----END OPENSSH PRIVATE KEY-----\n`
+  )
+}
+
+export function createOpenSshPublicKeyFixture(keyType: string): Buffer {
+  const encoded = sshString(keyType).toString('base64')
+  return Buffer.from(`${keyType} ${encoded} fixture-comment\n`)
+}
diff --git a/src/main/ssh/ssh-security-key-identity.test.ts b/src/main/ssh/ssh-security-key-identity.test.ts
new file mode 100644
index 00000000000..c424bfa6891
--- /dev/null
+++ b/src/main/ssh/ssh-security-key-identity.test.ts
@@ -0,0 +1,309 @@
+import { mkdir, mkdtemp, rm, writeFile } from 'node:fs/promises'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+import type { SshTarget } from '../../shared/ssh-types'
+import {
+  isOpenSshSecurityKeyPrivateKey,
+  isOpenSshSecurityKeyPublicKey
+} from './ssh-security-key-identity'
+import {
+  createOpenSshPrivateKeyFixture,
+  createOpenSshPublicKeyFixture
+} from './ssh-security-key-identity.test-fixture'
+import { requiresSystemSshForSecurityKey } from './ssh-transport-selection'
+
+const { findSystemSshMock } = vi.hoisted(() => ({ findSystemSshMock: vi.fn() }))
+
+vi.mock('./system-ssh-binary', () => ({ findSystemSsh: findSystemSshMock }))
+
+vi.mock('node:os', async (importOriginal) => {
+  const actual = await importOriginal<{ homedir: () => string }>()
+  return {
+    ...actual,
+    homedir: () => process.env.ORCA_TEST_SSH_HOME || actual.homedir()
+  }
+})
+
+const ED25519_SECURITY_KEY = 'sk-ssh-ed25519@openssh.com'
+const ECDSA_SECURITY_KEY = 'sk-ecdsa-sha2-nistp256@openssh.com'
+const tempDirs: string[] = []
+
+function createTarget(overrides: Partial<SshTarget> = {}): SshTarget {
+  return {
+    id: 'target-1',
+    label: 'Test Server',
+    host: 'example.com',
+    port: 22,
+    username: 'deploy',
+    ...overrides
+  }
+}
+
+beforeEach(() => {
+  findSystemSshMock.mockReset()
+  findSystemSshMock.mockReturnValue('/usr/bin/ssh')
+})
+
+async function writeKey(contents: Buffer, filename = 'security key'): Promise<string> {
+  const directory = await mkdtemp(join(tmpdir(), 'orca-security-key-'))
+  tempDirs.push(directory)
+  const keyPath = join(directory, filename)
+  await writeFile(keyPath, contents)
+  return keyPath
+}
+
+afterEach(async () => {
+  vi.unstubAllEnvs()
+  await Promise.all(tempDirs.splice(0).map((directory) => rm(directory, { recursive: true })))
+})
+
+describe('isOpenSshSecurityKeyPrivateKey', () => {
+  it.each([ED25519_SECURITY_KEY, ECDSA_SECURITY_KEY])(
+    'recognizes unencrypted %s keys',
+    (keyType) => {
+      expect(isOpenSshSecurityKeyPrivateKey(createOpenSshPrivateKeyFixture([keyType]))).toBe(true)
+    }
+  )
+
+  it('recognizes authenticated encrypted envelopes with a trailing tag', () => {
+    const key = createOpenSshPrivateKeyFixture([ED25519_SECURITY_KEY], {
+      cipher: 'aes256-gcm@openssh.com',
+      authTag: Buffer.alloc(16, 7)
+    })
+    expect(isOpenSshSecurityKeyPrivateKey(key)).toBe(true)
+  })
+
+  it.each([ED25519_SECURITY_KEY, ECDSA_SECURITY_KEY])(
+    'recognizes encrypted %s keys from the public section',
+    (keyType) => {
+      const key = createOpenSshPrivateKeyFixture([keyType], { encrypted: true })
+      expect(isOpenSshSecurityKeyPrivateKey(key)).toBe(true)
+    }
+  )
+
+  it.each(['ssh-ed25519', 'ecdsa-sha2-nistp256', 'ssh-rsa'])(
+    'leaves regular %s keys on ssh2',
+    (keyType) => {
+      expect(isOpenSshSecurityKeyPrivateKey(createOpenSshPrivateKeyFixture([keyType]))).toBe(false)
+    }
+  )
+
+  it('supports CRLF armored keys', () => {
+    const key = createOpenSshPrivateKeyFixture([ED25519_SECURITY_KEY])
+    expect(
+      isOpenSshSecurityKeyPrivateKey(Buffer.from(key.toString().replaceAll('\n', '\r\n')))
+    ).toBe(true)
+  })
+
+  it('recognizes OpenSSH envelopes without optional base64 padding', () => {
+    const key = createOpenSshPrivateKeyFixture([ED25519_SECURITY_KEY], {
+      privateBlock: Buffer.alloc(0)
+    })
+    const unpadded = Buffer.from(key.toString().replace(/=+(?=\n-----END)/, ''))
+    expect(unpadded).not.toEqual(key)
+    expect(isOpenSshSecurityKeyPrivateKey(unpadded)).toBe(true)
+  })
+
+  it('does not match security-key text outside a valid public-key type', () => {
+    const key = createOpenSshPrivateKeyFixture(['ssh-ed25519'], {
+      privateBlock: Buffer.from(ED25519_SECURITY_KEY)
+    })
+    expect(isOpenSshSecurityKeyPrivateKey(key)).toBe(false)
+    expect(
+      isOpenSshSecurityKeyPrivateKey(Buffer.from(`${ED25519_SECURITY_KEY} AAAA comment`))
+    ).toBe(false)
+  })
+
+  it.each([ED25519_SECURITY_KEY, ECDSA_SECURITY_KEY])(
+    'validates the %s type inside an OpenSSH public key blob',
+    (keyType) => {
+      expect(isOpenSshSecurityKeyPublicKey(createOpenSshPublicKeyFixture(keyType))).toBe(true)
+    }
+  )
+
+  it('recognizes public keys without optional base64 padding', () => {
+    const key = createOpenSshPublicKeyFixture(ECDSA_SECURITY_KEY)
+    const unpadded = Buffer.from(key.toString().replace(/=+(?=\s)/, ''))
+    expect(unpadded).not.toEqual(key)
+    expect(isOpenSshSecurityKeyPublicKey(unpadded)).toBe(true)
+  })
+
+  it('rejects regular or mismatched OpenSSH public key blobs', () => {
+    expect(isOpenSshSecurityKeyPublicKey(createOpenSshPublicKeyFixture('ssh-ed25519'))).toBe(false)
+    expect(
+      isOpenSshSecurityKeyPublicKey(
+        Buffer.from(`${ED25519_SECURITY_KEY} ${Buffer.from('ssh-ed25519').toString('base64')}`)
+      )
+    ).toBe(false)
+  })
+
+  it('rejects malformed and truncated OpenSSH envelopes without throwing', () => {
+    const key = createOpenSshPrivateKeyFixture([ED25519_SECURITY_KEY])
+    const malformedLength = Buffer.concat([
+      Buffer.from('openssh-key-v1\0', 'ascii'),
+      Buffer.from([0xff, 0xff, 0xff, 0xff])
+    ]).toString('base64')
+    const malformedKey = Buffer.from(
+      `-----BEGIN OPENSSH PRIVATE KEY-----\n${malformedLength}\n-----END OPENSSH PRIVATE KEY-----\n`
+    )
+    expect(isOpenSshSecurityKeyPrivateKey(key.subarray(0, -20))).toBe(false)
+    expect(isOpenSshSecurityKeyPrivateKey(malformedKey)).toBe(false)
+    expect(isOpenSshSecurityKeyPrivateKey(Buffer.from('not a private key'))).toBe(false)
+  })
+})
+
+describe('requiresSystemSshForSecurityKey', () => {
+  it('uses default FIDO2 identities only when config resolution is unavailable', async () => {
+    const directory = await mkdtemp(join(tmpdir(), 'orca-security-key-home-'))
+    tempDirs.push(directory)
+    await mkdir(join(directory, '.ssh'))
+    await writeFile(
+      join(directory, '.ssh', 'id_ed25519_sk'),
+      createOpenSshPrivateKeyFixture([ED25519_SECURITY_KEY])
+    )
+    vi.stubEnv('ORCA_TEST_SSH_HOME', directory)
+
+    await expect(requiresSystemSshForSecurityKey(createTarget(), null)).resolves.toBe(true)
+    await expect(
+      requiresSystemSshForSecurityKey(createTarget(), { identityFile: [] })
+    ).resolves.toBe(false)
+  })
+
+  it('keeps a regular default ahead of a dormant FIDO2 identity', async () => {
+    const directory = await mkdtemp(join(tmpdir(), 'orca-regular-key-home-'))
+    tempDirs.push(directory)
+    await mkdir(join(directory, '.ssh'))
+    await writeFile(join(directory, '.ssh', 'id_rsa'), createOpenSshPrivateKeyFixture(['ssh-rsa']))
+    await writeFile(
+      join(directory, '.ssh', 'id_ed25519_sk'),
+      createOpenSshPrivateKeyFixture([ED25519_SECURITY_KEY])
+    )
+    vi.stubEnv('ORCA_TEST_SSH_HOME', directory)
+
+    await expect(requiresSystemSshForSecurityKey(createTarget(), null)).resolves.toBe(false)
+  })
+
+  it('keeps password and agent fallback when default FIDO2 needs unavailable OpenSSH', async () => {
+    const directory = await mkdtemp(join(tmpdir(), 'orca-no-system-ssh-home-'))
+    tempDirs.push(directory)
+    await mkdir(join(directory, '.ssh'))
+    await writeFile(
+      join(directory, '.ssh', 'id_ed25519_sk'),
+      createOpenSshPrivateKeyFixture([ED25519_SECURITY_KEY])
+    )
+    vi.stubEnv('ORCA_TEST_SSH_HOME', directory)
+    findSystemSshMock.mockReturnValue(null)
+
+    await expect(requiresSystemSshForSecurityKey(createTarget(), null)).resolves.toBe(false)
+  })
+
+  it('ignores an orphan regular sidecar before a valid default FIDO2 identity', async () => {
+    const directory = await mkdtemp(join(tmpdir(), 'orca-orphan-sidecar-home-'))
+    tempDirs.push(directory)
+    await mkdir(join(directory, '.ssh'))
+    await writeFile(
+      join(directory, '.ssh', 'id_ed25519.pub'),
+      createOpenSshPublicKeyFixture('ssh-ed25519')
+    )
+    await writeFile(
+      join(directory, '.ssh', 'id_ed25519_sk'),
+      createOpenSshPrivateKeyFixture([ED25519_SECURITY_KEY])
+    )
+    vi.stubEnv('ORCA_TEST_SSH_HOME', directory)
+
+    await expect(requiresSystemSshForSecurityKey(createTarget(), null)).resolves.toBe(true)
+  })
+
+  it('detects a manual target identity path with spaces', async () => {
+    const keyPath = await writeKey(createOpenSshPrivateKeyFixture([ED25519_SECURITY_KEY]))
+    await expect(
+      requiresSystemSshForSecurityKey(createTarget({ identityFile: keyPath }), null)
+    ).resolves.toBe(true)
+  })
+
+  it('checks every fresh resolved identity for config-backed targets', async () => {
+    const regularKey = await writeKey(createOpenSshPrivateKeyFixture(['ssh-ed25519']), 'regular')
+    const securityKey = await writeKey(
+      createOpenSshPrivateKeyFixture([ECDSA_SECURITY_KEY], { encrypted: true }),
+      'security'
+    )
+    const target = createTarget({
+      source: 'ssh-config',
+      configHost: 'workbox',
+      identityFile: '/stale/security-key'
+    })
+
+    await expect(
+      requiresSystemSshForSecurityKey(target, { identityFile: [regularKey, securityKey] })
+    ).resolves.toBe(true)
+  })
+
+  it.each([ED25519_SECURITY_KEY, ECDSA_SECURITY_KEY])(
+    'detects an agent-backed %s identity from its public sidecar',
+    async (keyType) => {
+      const directory = await mkdtemp(join(tmpdir(), 'orca-security-key-agent-'))
+      tempDirs.push(directory)
+      const identityPath = join(directory, 'agent-key')
+      await writeFile(`${identityPath}.pub`, createOpenSshPublicKeyFixture(keyType))
+
+      await expect(
+        requiresSystemSshForSecurityKey(createTarget({ identityFile: identityPath }), null)
+      ).resolves.toBe(true)
+    }
+  )
+
+  it('ignores a stale FIDO2 sidecar beside a regular private identity', async () => {
+    const identityPath = await writeKey(
+      createOpenSshPrivateKeyFixture(['ssh-ed25519']),
+      'regular-with-stale-sidecar'
+    )
+    await writeFile(`${identityPath}.pub`, createOpenSshPublicKeyFixture(ED25519_SECURITY_KEY))
+
+    await expect(
+      requiresSystemSshForSecurityKey(createTarget({ identityFile: identityPath }), null)
+    ).resolves.toBe(false)
+  })
+
+  it('ignores stale imported identity paths when fresh config has regular keys', async () => {
+    const staleKey = await writeKey(createOpenSshPrivateKeyFixture([ED25519_SECURITY_KEY]), 'stale')
+    const regularKey = await writeKey(createOpenSshPrivateKeyFixture(['ssh-ed25519']), 'regular')
+    const target = createTarget({
+      source: 'ssh-config',
+      configHost: 'workbox',
+      identityFile: staleKey
+    })
+
+    await expect(
+      requiresSystemSshForSecurityKey(target, { identityFile: [regularKey] })
+    ).resolves.toBe(false)
+  })
+
+  it('keeps a manual target identity authoritative over resolved defaults', async () => {
+    const regularKey = await writeKey(createOpenSshPrivateKeyFixture(['ssh-ed25519']), 'manual')
+    const securityKey = await writeKey(
+      createOpenSshPrivateKeyFixture([ED25519_SECURITY_KEY]),
+      'resolved'
+    )
+
+    await expect(
+      requiresSystemSshForSecurityKey(
+        createTarget({ source: 'manual', identityFile: regularKey }),
+        { identityFile: [securityKey] }
+      )
+    ).resolves.toBe(false)
+  })
+
+  it('degrades to ssh2 when identity files are missing or malformed', async () => {
+    const malformedKey = await writeKey(Buffer.from('not a key'), 'malformed')
+    await expect(
+      requiresSystemSshForSecurityKey(createTarget({ identityFile: malformedKey }), null)
+    ).resolves.toBe(false)
+    await expect(
+      requiresSystemSshForSecurityKey(
+        createTarget({ identityFile: join(tmpdir(), 'missing-security-key') }),
+        null
+      )
+    ).resolves.toBe(false)
+  })
+})
diff --git a/src/main/ssh/ssh-security-key-identity.ts b/src/main/ssh/ssh-security-key-identity.ts
new file mode 100644
index 00000000000..bb1af581d7d
--- /dev/null
+++ b/src/main/ssh/ssh-security-key-identity.ts
@@ -0,0 +1,107 @@
+const OPENSSH_PRIVATE_KEY_HEADER = '-----BEGIN OPENSSH PRIVATE KEY-----'
+const OPENSSH_PRIVATE_KEY_FOOTER = '-----END OPENSSH PRIVATE KEY-----'
+const OPENSSH_KEY_MAGIC = Buffer.from('openssh-key-v1\0', 'ascii')
+export const MAX_SSH_IDENTITY_FILE_BYTES = 1024 * 1024
+const MAX_PUBLIC_KEYS = 64
+const SECURITY_KEY_TYPES = new Set([
+  'sk-ssh-ed25519@openssh.com',
+  'sk-ecdsa-sha2-nistp256@openssh.com'
+])
+
+type SshString = { value: Buffer; nextOffset: number }
+
+function decodeBase64(value: string): Buffer | null {
+  if (!value || value.length % 4 === 1 || !/^[A-Za-z0-9+/]+={0,2}$/.test(value)) {
+    return null
+  }
+  const unpadded = value.replace(/=+$/, '')
+  const decoded = Buffer.from(unpadded, 'base64')
+  return decoded.toString('base64').replace(/=+$/, '') === unpadded ? decoded : null
+}
+
+function readSshString(buffer: Buffer, offset: number): SshString | null {
+  if (offset < 0 || offset + 4 > buffer.length) {
+    return null
+  }
+  const length = buffer.readUInt32BE(offset)
+  const start = offset + 4
+  const end = start + length
+  if (end < start || end > buffer.length) {
+    return null
+  }
+  return { value: buffer.subarray(start, end), nextOffset: end }
+}
+
+function decodeOpenSshPrivateKey(contents: Buffer): Buffer | null {
+  if (contents.length > MAX_SSH_IDENTITY_FILE_BYTES) {
+    return null
+  }
+  const lines = contents.toString('ascii').trim().split(/\r?\n/)
+  if (lines[0] !== OPENSSH_PRIVATE_KEY_HEADER || lines.at(-1) !== OPENSSH_PRIVATE_KEY_FOOTER) {
+    return null
+  }
+  const encoded = lines.slice(1, -1).join('')
+  const decoded = decodeBase64(encoded)
+  if (!decoded) {
+    return null
+  }
+  return decoded.subarray(0, OPENSSH_KEY_MAGIC.length).equals(OPENSSH_KEY_MAGIC) ? decoded : null
+}
+
+export function isOpenSshSecurityKeyPrivateKey(contents: Buffer): boolean {
+  const decoded = decodeOpenSshPrivateKey(contents)
+  if (!decoded) {
+    return false
+  }
+
+  let offset = OPENSSH_KEY_MAGIC.length
+  for (let field = 0; field < 3; field++) {
+    const value = readSshString(decoded, offset)
+    if (!value) {
+      return false
+    }
+    offset = value.nextOffset
+  }
+  if (offset + 4 > decoded.length) {
+    return false
+  }
+
+  const keyCount = decoded.readUInt32BE(offset)
+  offset += 4
+  if (keyCount === 0 || keyCount > MAX_PUBLIC_KEYS) {
+    return false
+  }
+
+  let hasSecurityKey = false
+  for (let keyIndex = 0; keyIndex < keyCount; keyIndex++) {
+    const publicKey = readSshString(decoded, offset)
+    if (!publicKey) {
+      return false
+    }
+    offset = publicKey.nextOffset
+    const keyType = readSshString(publicKey.value, 0)
+    if (!keyType) {
+      return false
+    }
+    hasSecurityKey ||= SECURITY_KEY_TYPES.has(keyType.value.toString('ascii'))
+  }
+
+  const privateBlock = readSshString(decoded, offset)
+  return privateBlock !== null && hasSecurityKey
+}
+
+export function isOpenSshSecurityKeyPublicKey(contents: Buffer): boolean {
+  if (contents.length > MAX_SSH_IDENTITY_FILE_BYTES) {
+    return false
+  }
+  const [declaredType, encoded] = contents.toString('ascii').trim().split(/\s+/, 3)
+  if (!declaredType || !encoded || !SECURITY_KEY_TYPES.has(declaredType)) {
+    return false
+  }
+  const decoded = decodeBase64(encoded)
+  if (!decoded) {
+    return false
+  }
+  const keyType = readSshString(decoded, 0)
+  return keyType?.value.toString('ascii') === declaredType
+}
diff --git a/src/main/ssh/ssh-system-fallback.test.ts b/src/main/ssh/ssh-system-fallback.test.ts
index 36312762d08..03e3e8baf53 100644
--- a/src/main/ssh/ssh-system-fallback.test.ts
+++ b/src/main/ssh/ssh-system-fallback.test.ts
@@ -24,7 +24,6 @@ vi.mock('child_process', () => ({
 
 import {
   buildSshArgs,
-  findSystemSsh,
   downloadFileViaSystemSsh,
   spawnSystemSsh,
   spawnSystemSshCommand,
@@ -152,22 +151,6 @@ function createMockChildProcess(): EventEmitter & {
   return child
 }
 
-describe('findSystemSsh', () => {
-  beforeEach(() => {
-    existsSyncMock.mockReset()
-  })
-
-  it('returns the first existing ssh path', () => {
-    mockSystemSshExists()
-    expect(findSystemSsh()).toBe(SYSTEM_SSH_PATH)
-  })
-
-  it('returns null when no ssh binary is found', () => {
-    existsSyncMock.mockReturnValue(false)
-    expect(findSystemSsh()).toBeNull()
-  })
-})
-
 describe('spawnSystemSsh', () => {
   let mockProc: {
     stdin: {
@@ -827,6 +810,7 @@ describe('spawnSystemSsh', () => {
 
   it('throws when no system ssh is found', () => {
     existsSyncMock.mockReturnValue(false)
+    vi.stubEnv('PATH', '')
     expect(() => spawnSystemSsh(createTarget())).toThrow('No system ssh binary found')
   })
 
diff --git a/src/main/ssh/ssh-transport-selection.ts b/src/main/ssh/ssh-transport-selection.ts
new file mode 100644
index 00000000000..fdbfb87075f
--- /dev/null
+++ b/src/main/ssh/ssh-transport-selection.ts
@@ -0,0 +1,118 @@
+import { constants } from 'node:fs'
+import { open, stat } from 'node:fs/promises'
+import type { SshTarget } from '../../shared/ssh-types'
+import type { SshResolvedConfig } from './ssh-config-parser'
+import { listDefaultIdentityFilePaths, resolveIdentityFilePaths } from './ssh-auth-resolution'
+import { resolveSshConfigHomePath } from './ssh-config-path-expansion'
+import {
+  MAX_SSH_IDENTITY_FILE_BYTES,
+  isOpenSshSecurityKeyPrivateKey,
+  isOpenSshSecurityKeyPublicKey
+} from './ssh-security-key-identity'
+import { isOpenSshConfigBackedTarget } from './system-ssh-args'
+import { findSystemSsh } from './system-ssh-binary'
+
+type TransportResolvedConfig = Pick<
+  SshResolvedConfig,
+  'proxyUseFdpass' | 'proxyCommand' | 'proxyJump'
+>
+
+const READ_CHUNK_BYTES = 64 * 1024
+const READ_OPEN_FLAGS =
+  constants.O_RDONLY | (process.platform === 'win32' ? 0 : constants.O_NONBLOCK)
+
+type IdentityInspection = { privateIdentityExists: boolean; requiresSystemSsh: boolean }
+
+async function readBoundedKeyFile(path: string): Promise<Buffer | null> {
+  let handle: Awaited<ReturnType<typeof open>> | undefined
+  try {
+    const pathStats = await stat(path)
+    if (!pathStats.isFile() || pathStats.size > MAX_SSH_IDENTITY_FILE_BYTES) {
+      return null
+    }
+    handle = await open(path, READ_OPEN_FLAGS)
+    const stats = await handle.stat()
+    if (!stats.isFile() || stats.size > MAX_SSH_IDENTITY_FILE_BYTES) {
+      return null
+    }
+    const chunks: Buffer[] = []
+    let offset = 0
+    while (offset <= MAX_SSH_IDENTITY_FILE_BYTES) {
+      const buffer = Buffer.alloc(
+        Math.min(READ_CHUNK_BYTES, MAX_SSH_IDENTITY_FILE_BYTES + 1 - offset)
+      )
+      const { bytesRead } = await handle.read(buffer, 0, buffer.length, offset)
+      if (bytesRead === 0) {
+        break
+      }
+      offset += bytesRead
+      if (offset > MAX_SSH_IDENTITY_FILE_BYTES) {
+        return null
+      }
+      chunks.push(buffer.subarray(0, bytesRead))
+    }
+    return Buffer.concat(chunks, offset)
+  } catch {
+    return null
+  } finally {
+    await handle?.close().catch(() => undefined)
+  }
+}
+
+async function inspectIdentityPath(keyPath: string): Promise<IdentityInspection> {
+  const resolvedPath = resolveSshConfigHomePath(keyPath)
+  const identity = await readBoundedKeyFile(resolvedPath)
+  if (identity !== null) {
+    return {
+      privateIdentityExists: true,
+      requiresSystemSsh:
+        isOpenSshSecurityKeyPublicKey(identity) || isOpenSshSecurityKeyPrivateKey(identity)
+    }
+  }
+  const publicIdentity = await readBoundedKeyFile(`${resolvedPath}.pub`)
+  return {
+    privateIdentityExists: false,
+    requiresSystemSsh: publicIdentity !== null && isOpenSshSecurityKeyPublicKey(publicIdentity)
+  }
+}
+
+export function shouldUseSystemSshTransport(
+  target: SshTarget,
+  resolved: TransportResolvedConfig | null
+): boolean {
+  if (isOpenSshConfigBackedTarget(target) && resolved) {
+    return (
+      process.env.ORCA_SSH_FORCE_SYSTEM_TRANSPORT === '1' ||
+      resolved.proxyUseFdpass === true ||
+      resolved.proxyCommand != null ||
+      resolved.proxyJump != null
+    )
+  }
+  return (
+    process.env.ORCA_SSH_FORCE_SYSTEM_TRANSPORT === '1' ||
+    target.proxyCommand != null ||
+    target.jumpHost != null ||
+    resolved?.proxyUseFdpass === true ||
+    resolved?.proxyCommand != null ||
+    resolved?.proxyJump != null
+  )
+}
+
+export async function requiresSystemSshForSecurityKey(
+  target: SshTarget,
+  resolved: Pick<SshResolvedConfig, 'identityFile'> | null
+): Promise<boolean> {
+  const configuredPaths = resolveIdentityFilePaths(target, resolved)
+  const usesDefaultPaths = configuredPaths.length === 0 && !resolved && !target.identityFile
+  const identityPaths = usesDefaultPaths ? listDefaultIdentityFilePaths() : configuredPaths
+  for (const keyPath of identityPaths) {
+    const inspection = await inspectIdentityPath(keyPath)
+    if (inspection.requiresSystemSsh) {
+      return !usesDefaultPaths || findSystemSsh() !== null
+    }
+    if (usesDefaultPaths && inspection.privateIdentityExists) {
+      return false
+    }
+  }
+  return false
+}
diff --git a/src/main/ssh/system-ssh-binary.test.ts b/src/main/ssh/system-ssh-binary.test.ts
new file mode 100644
index 00000000000..a3be418d2fc
--- /dev/null
+++ b/src/main/ssh/system-ssh-binary.test.ts
@@ -0,0 +1,106 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+const { accessSyncMock, existsSyncMock, statSyncMock } = vi.hoisted(() => ({
+  accessSyncMock: vi.fn(),
+  existsSyncMock: vi.fn(),
+  statSyncMock: vi.fn()
+}))
+
+vi.mock('node:fs', () => ({
+  accessSync: accessSyncMock,
+  constants: { O_RDONLY: 0, O_NONBLOCK: 4, X_OK: 1 },
+  existsSync: existsSyncMock,
+  statSync: statSyncMock
+}))
+
+import { findSystemSsh } from './system-ssh-binary'
+
+describe('findSystemSsh', () => {
+  beforeEach(() => {
+    accessSyncMock.mockReset()
+    existsSyncMock.mockReset()
+    statSyncMock.mockReset()
+    statSyncMock.mockImplementation(() => {
+      throw new Error('missing')
+    })
+    vi.unstubAllEnvs()
+  })
+
+  afterEach(() => {
+    vi.unstubAllEnvs()
+  })
+
+  it('returns the first existing fixed ssh path', () => {
+    const platformSpy = vi.spyOn(process, 'platform', 'get').mockReturnValue('linux')
+    existsSyncMock.mockImplementation((path: string) => path === '/usr/bin/ssh')
+
+    try {
+      expect(findSystemSsh()).toBe('/usr/bin/ssh')
+    } finally {
+      platformSpy.mockRestore()
+    }
+  })
+
+  it('returns null when no ssh binary is found', () => {
+    existsSyncMock.mockReturnValue(false)
+    expect(findSystemSsh()).toBeNull()
+  })
+
+  it('finds a PATH-installed ssh.exe on Windows', () => {
+    const platformSpy = vi.spyOn(process, 'platform', 'get').mockReturnValue('win32')
+    vi.stubEnv('PATH', 'C:\\Git\\usr\\bin;C:\\Tools')
+    existsSyncMock.mockReturnValue(false)
+    statSyncMock.mockImplementation((path: string) => {
+      if (path === 'C:\\Git\\usr\\bin\\ssh.exe') {
+        return { isFile: () => true }
+      }
+      throw new Error('missing')
+    })
+
+    try {
+      expect(findSystemSsh()).toBe('C:\\Git\\usr\\bin\\ssh.exe')
+    } finally {
+      platformSpy.mockRestore()
+    }
+  })
+
+  it('finds an executable PATH-installed ssh on POSIX', () => {
+    const platformSpy = vi.spyOn(process, 'platform', 'get').mockReturnValue('linux')
+    vi.stubEnv('PATH', '/nix/store/ssh/bin:/opt/tools')
+    existsSyncMock.mockReturnValue(false)
+    statSyncMock.mockImplementation((path: string) => {
+      if (path === '/nix/store/ssh/bin/ssh') {
+        return { isFile: () => true }
+      }
+      throw new Error('missing')
+    })
+
+    try {
+      expect(findSystemSsh()).toBe('/nix/store/ssh/bin/ssh')
+      expect(accessSyncMock).toHaveBeenCalledWith('/nix/store/ssh/bin/ssh', expect.any(Number))
+    } finally {
+      platformSpy.mockRestore()
+    }
+  })
+
+  it('resolves Windows OpenSSH from the runtime system root', () => {
+    const platformSpy = vi.spyOn(process, 'platform', 'get').mockReturnValue('win32')
+    vi.stubEnv('SystemRoot', 'D:\\Windows')
+    existsSyncMock.mockImplementation(
+      (path: string) => path === 'D:\\Windows\\System32\\OpenSSH\\ssh.exe'
+    )
+
+    try {
+      expect(findSystemSsh()).toBe('D:\\Windows\\System32\\OpenSSH\\ssh.exe')
+    } finally {
+      platformSpy.mockRestore()
+    }
+  })
+
+  it('keeps an explicit system ssh override authoritative', () => {
+    vi.stubEnv('ORCA_SYSTEM_SSH_PATH', 'C:\\Custom\\ssh.exe')
+
+    expect(findSystemSsh()).toBe('C:\\Custom\\ssh.exe')
+    expect(existsSyncMock).not.toHaveBeenCalled()
+  })
+})
diff --git a/src/main/ssh/system-ssh-binary.ts b/src/main/ssh/system-ssh-binary.ts
index 579b483392c..bc8ff3ea516 100644
--- a/src/main/ssh/system-ssh-binary.ts
+++ b/src/main/ssh/system-ssh-binary.ts
@@ -1,9 +1,41 @@
-import { existsSync } from 'node:fs'
+import { accessSync, constants, existsSync, statSync } from 'node:fs'
+import { posix, win32 } from 'node:path'
 
-const SYSTEM_SSH_PATHS =
-  process.platform === 'win32'
-    ? ['C:\\Windows\\System32\\OpenSSH\\ssh.exe', 'ssh.exe']
-    : ['/usr/bin/ssh', '/usr/local/bin/ssh', '/opt/homebrew/bin/ssh']
+function systemSshPaths(platform: NodeJS.Platform): string[] {
+  if (platform !== 'win32') {
+    return ['/usr/bin/ssh', '/usr/local/bin/ssh', '/opt/homebrew/bin/ssh']
+  }
+  const systemRoot = process.env.SystemRoot || process.env.WINDIR
+  return systemRoot ? [win32.join(systemRoot, 'System32', 'OpenSSH', 'ssh.exe')] : []
+}
+
+function findSshOnPath(platform: NodeJS.Platform): string | null {
+  const pathValue = process.env.PATH
+  if (!pathValue) {
+    return null
+  }
+  const pathApi = platform === 'win32' ? win32 : posix
+  const executable = platform === 'win32' ? 'ssh.exe' : 'ssh'
+  for (const entry of pathValue.split(pathApi.delimiter)) {
+    const directory = entry.trim().replace(/^"|"$/g, '')
+    if (!directory) {
+      continue
+    }
+    const candidate = pathApi.join(directory, executable)
+    try {
+      if (!statSync(candidate).isFile()) {
+        continue
+      }
+      if (platform !== 'win32') {
+        accessSync(candidate, constants.X_OK)
+      }
+      return candidate
+    } catch {
+      continue
+    }
+  }
+  return null
+}
 
 /**
  * Find the system ssh binary path. Returns null if not found.
@@ -12,10 +44,10 @@ export function findSystemSsh(): string | null {
   if (process.env.ORCA_SYSTEM_SSH_PATH) {
     return process.env.ORCA_SYSTEM_SSH_PATH
   }
-  for (const candidate of SYSTEM_SSH_PATHS) {
+  for (const candidate of systemSshPaths(process.platform)) {
     if (existsSync(candidate)) {
       return candidate
     }
   }
-  return null
+  return findSshOnPath(process.platform)
 }
diff --git a/src/main/window/createMainWindow.test.ts b/src/main/window/createMainWindow.test.ts
index fc38ca95e77..8a61f157584 100644
--- a/src/main/window/createMainWindow.test.ts
+++ b/src/main/window/createMainWindow.test.ts
@@ -74,6 +74,8 @@ import {
 } from './createMainWindow'
 import { ipcMain } from 'electron'
 import { shouldRecoverRendererAfterProcessGone } from '../crash-reporting/process-gone-classification'
+import { BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD } from '../../shared/browser-window-close-policy'
+import { fileURLToPath } from 'node:url'
 
 function withPlatform<T>(platform: NodeJS.Platform, run: () => T): T {
   const original = process.platform
@@ -248,6 +250,7 @@ describe('createMainWindow', () => {
     expect(allowBlankPrefs).toMatchObject({
       disableHtmlFullscreenWindowResize: true,
       partition: 'persist:orca-browser',
+      preload: expect.stringMatching(/browser-window-close-preload\.js$/),
       sandbox: true
     })
 
@@ -262,6 +265,36 @@ describe('createMainWindow', () => {
     const guest = { marker: 'guest' }
     windowHandlers['did-attach-webview']({} as never, guest as never)
     expect(attachGuestPoliciesMock).toHaveBeenCalledWith(guest)
+
+    const allowWindowCloseEvent = { preventDefault: vi.fn() }
+    const allowWindowCloseParams = {
+      src: 'data:text/html,',
+      preload: BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD
+    }
+    const allowWindowClosePrefs = { partition: 'persist:orca-browser' }
+    windowHandlers['will-attach-webview'](
+      allowWindowCloseEvent as never,
+      allowWindowClosePrefs as never,
+      allowWindowCloseParams as never
+    )
+    expect(allowWindowCloseEvent.preventDefault).not.toHaveBeenCalled()
+    expect(allowWindowCloseParams.preload).toBeUndefined()
+    expect(allowWindowClosePrefs).not.toHaveProperty('preload')
+
+    const allowWindowClosePathPrefs = {
+      partition: 'persist:orca-browser',
+      preload: fileURLToPath(BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD)
+    }
+    windowHandlers['will-attach-webview'](
+      { preventDefault: vi.fn() } as never,
+      allowWindowClosePathPrefs as never,
+      { src: 'data:text/html,', preload: '' } as never
+    )
+    expect(allowWindowClosePathPrefs).not.toHaveProperty('preload')
+
+    const cliGuest = { marker: 'cli-guest' }
+    windowHandlers['did-attach-webview']({} as never, cliGuest as never)
+    expect(attachGuestPoliciesMock).toHaveBeenLastCalledWith(cliGuest)
   })
 
   it('sets platform-specific titlebar and frame options for every desktop platform', () => {
diff --git a/src/main/window/createMainWindow.ts b/src/main/window/createMainWindow.ts
index 519e1817051..49c3eb4c125 100644
--- a/src/main/window/createMainWindow.ts
+++ b/src/main/window/createMainWindow.ts
@@ -10,6 +10,7 @@ import {
   screen
 } from 'electron'
 import { join } from 'node:path'
+import { fileURLToPath } from 'node:url'
 import { is } from '@electron-toolkit/utils'
 import type { Store } from '../persistence'
 import { getAppIconPath } from '../app-icon'
@@ -18,6 +19,7 @@ import { browserSessionRegistry } from '../browser/browser-session-registry'
 import { translateMain } from '../i18n/main-i18n'
 import { normalizeBrowserNavigationUrl } from '../../shared/browser-url'
 import { ORCA_BROWSER_GUEST_WEB_PREFERENCES } from '../../shared/browser-guest-web-preferences'
+import { BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD } from '../../shared/browser-window-close-policy'
 import { isCrashReportReason } from '../../shared/crash-reporting'
 import {
   DEFAULT_RENDERER_RECOVERY_MAX_RECOVERIES,
@@ -441,6 +443,8 @@ export function createMainWindow(
   // so register it with the window's other navigation policy.
   registerPluginPanelNavigationGuard(mainWindow.webContents)
 
+  const browserWindowClosePreload = join(__dirname, 'browser-window-close-preload.js')
+  const browserWindowCloseAllowedPreloadPath = fileURLToPath(BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD)
   mainWindow.webContents.on('will-attach-webview', (event, webPreferences, params) => {
     const src = typeof params.src === 'string' ? params.src : ''
     const normalizedSrc = normalizeBrowserNavigationUrl(src)
@@ -452,7 +456,18 @@ export function createMainWindow(
       return
     }
 
-    delete webPreferences.preload
+    const allowWindowClose = [params.preload, webPreferences.preload].some(
+      (preload) =>
+        preload === BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD ||
+        preload === browserWindowCloseAllowedPreloadPath
+    )
+    delete params.preload
+    if (allowWindowClose) {
+      delete webPreferences.preload
+    } else {
+      // Why: preload runs in the page's main world before inline scripts can call window.close().
+      webPreferences.preload = browserWindowClosePreload
+    }
     // Why: older Electron builds expose preloadURL alongside preload; delete both so the guest can't inherit the main preload bridge.
     delete (webPreferences as Record<string, unknown>).preloadURL
     webPreferences.nodeIntegration = false
diff --git a/src/preload/browser-window-close-installation.ts b/src/preload/browser-window-close-installation.ts
new file mode 100644
index 00000000000..adf2fdb09bf
--- /dev/null
+++ b/src/preload/browser-window-close-installation.ts
@@ -0,0 +1,15 @@
+export function installBrowserWindowCloseGuard(): void {
+  const ignoreWindowClose = (): void => {}
+  try {
+    Object.defineProperty(window, 'close', {
+      configurable: false,
+      enumerable: false,
+      writable: false,
+      value: ignoreWindowClose
+    })
+  } catch {
+    try {
+      window.close = ignoreWindowClose
+    } catch {}
+  }
+}
diff --git a/src/preload/browser-window-close.test.ts b/src/preload/browser-window-close.test.ts
new file mode 100644
index 00000000000..1b35a45f8df
--- /dev/null
+++ b/src/preload/browser-window-close.test.ts
@@ -0,0 +1,20 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+
+import { installBrowserWindowCloseGuard } from './browser-window-close-installation'
+
+describe('browser window close preload', () => {
+  afterEach(() => {
+    vi.unstubAllGlobals()
+  })
+
+  it('installs a non-replaceable window.close no-op in the page world', () => {
+    const nativeClose = vi.fn()
+    vi.stubGlobal('window', { close: nativeClose })
+
+    installBrowserWindowCloseGuard()
+
+    expect(window.close()).toBeUndefined()
+    expect(window.close).not.toBe(nativeClose)
+    expect(Reflect.set(window, 'close', nativeClose)).toBe(false)
+  })
+})
diff --git a/src/preload/browser-window-close.ts b/src/preload/browser-window-close.ts
new file mode 100644
index 00000000000..7fb8201377f
--- /dev/null
+++ b/src/preload/browser-window-close.ts
@@ -0,0 +1,7 @@
+import { installBrowserWindowCloseGuard } from './browser-window-close-installation'
+import type { ContextBridge } from 'electron'
+
+// Why: raw require keeps the sandboxed preload standalone in the main-process CJS build.
+const { contextBridge } = require('electron') as { contextBridge: ContextBridge }
+
+contextBridge.executeInMainWorld({ func: installBrowserWindowCloseGuard })
diff --git a/src/renderer/src/components/browser-pane/BrowserPane.tsx b/src/renderer/src/components/browser-pane/BrowserPane.tsx
index 1a2c0279543..60cc98d8d7c 100644
--- a/src/renderer/src/components/browser-pane/BrowserPane.tsx
+++ b/src/renderer/src/components/browser-pane/BrowserPane.tsx
@@ -3693,6 +3693,7 @@ function BrowserPagePane({
       container,
       inputLocked: inputLockedRef.current,
       webviewPartition,
+      allowWindowClose: browserTab.allowWindowClose === true,
       resolveContainer: () =>
         ensureBrowserPageViewport(browserTab.id, workspaceId)?.container ?? null
     })
diff --git a/src/renderer/src/components/browser-pane/BrowserPane.webview-preferences.test.ts b/src/renderer/src/components/browser-pane/BrowserPane.webview-preferences.test.ts
index 203fce6fdbf..496b23ec409 100644
--- a/src/renderer/src/components/browser-pane/BrowserPane.webview-preferences.test.ts
+++ b/src/renderer/src/components/browser-pane/BrowserPane.webview-preferences.test.ts
@@ -1,6 +1,7 @@
 // @vitest-environment happy-dom
 import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
 import { ORCA_BROWSER_GUEST_WEB_PREFERENCES_ATTRIBUTE } from '../../../../shared/browser-guest-web-preferences'
+import { BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD } from '../../../../shared/browser-window-close-policy'
 
 const registryMocks = vi.hoisted(() => ({
   destroyPersistentWebview: vi.fn(),
@@ -103,4 +104,22 @@ describe('BrowserPane webview preferences', () => {
     expect(ensuredWebview?.webview.style.pointerEvents).toBe('none')
     expect(refreshedContainer.lastElementChild).toBe(ensuredWebview?.webview as unknown as Element)
   })
+
+  it('marks explicitly allowed CLI pages before the guest attaches', () => {
+    const container = createContainer('cli-page')
+
+    const ensuredWebview = ensureBrowserPageWebview({
+      browserTabId: 'browser-page-cli',
+      container,
+      inputLocked: false,
+      webviewPartition: 'persist:orca-browser',
+      allowWindowClose: true,
+      resolveContainer: () => container
+    })
+
+    expect(ensuredWebview?.webview.getAttribute('preload')).toBe(
+      BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD
+    )
+    expect(BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD).toMatch(/^file:/)
+  })
 })
diff --git a/src/renderer/src/components/browser-pane/browser-page-webview.ts b/src/renderer/src/components/browser-pane/browser-page-webview.ts
index 1179d0da63b..b8c44d849ad 100644
--- a/src/renderer/src/components/browser-pane/browser-page-webview.ts
+++ b/src/renderer/src/components/browser-pane/browser-page-webview.ts
@@ -1,4 +1,5 @@
 import { ORCA_BROWSER_GUEST_WEB_PREFERENCES_ATTRIBUTE } from '../../../../shared/browser-guest-web-preferences'
+import { BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD } from '../../../../shared/browser-window-close-policy'
 import {
   destroyPersistentWebview,
   registerPersistentWebview,
@@ -10,12 +11,14 @@ export function ensureBrowserPageWebview({
   container,
   inputLocked,
   webviewPartition,
+  allowWindowClose,
   resolveContainer
 }: {
   browserTabId: string
   container: HTMLDivElement
   inputLocked: boolean
   webviewPartition: string
+  allowWindowClose?: boolean
   resolveContainer: () => HTMLDivElement | null
 }): { container: HTMLDivElement; created: boolean; webview: Electron.WebviewTag } | null {
   let webview = webviewRegistry.get(browserTabId)
@@ -46,6 +49,10 @@ export function ensureBrowserPageWebview({
 
   webview = document.createElement('webview') as Electron.WebviewTag
   webview.setAttribute('partition', webviewPartition)
+  if (allowWindowClose) {
+    // Why: main consumes and removes this marker in will-attach-webview before the guest sees any preload.
+    webview.setAttribute('preload', BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD)
+  }
   webview.setAttribute('allowpopups', '')
   // Why: Electron spreads the webpreferences keys verbatim, so the shared
   // camelCase attribute must stay intact for fullscreen containment to work.
diff --git a/src/renderer/src/components/terminal-pane/terminal-visibility-resume.test.ts b/src/renderer/src/components/terminal-pane/terminal-visibility-resume.test.ts
index 300a381c05a..17271179620 100644
--- a/src/renderer/src/components/terminal-pane/terminal-visibility-resume.test.ts
+++ b/src/renderer/src/components/terminal-pane/terminal-visibility-resume.test.ts
@@ -151,6 +151,50 @@ describe('resumeTerminalVisibility reveal repaint', () => {
     expect(manager.fitAllPanes).not.toHaveBeenCalled()
   })
 
+  it('latches viewport intent before refocus recovery flushes streaming output', async () => {
+    const terminal = { name: 'streaming-terminal' }
+    const manager = createManager()
+    manager.getPanes.mockReturnValue([{ terminal }])
+    const { syncTerminalScrollIntentFromViewport } = vi.mocked(
+      await import('@/lib/pane-manager/terminal-scroll-intent')
+    )
+    const { flushTerminalOutput } = vi.mocked(
+      await import('@/lib/pane-manager/pane-terminal-output-scheduler')
+    )
+
+    recoverVisibleTerminalWindowWake({
+      manager: manager as never as PaneManager,
+      isActive: true,
+      clearGlyphAtlases: false
+    })
+
+    expect(flushTerminalOutput).toHaveBeenCalledOnce()
+    expect(syncTerminalScrollIntentFromViewport).toHaveBeenCalledOnce()
+    expect(syncTerminalScrollIntentFromViewport.mock.invocationCallOrder[0]).toBeLessThan(
+      flushTerminalOutput.mock.invocationCallOrder[0] ?? Number.POSITIVE_INFINITY
+    )
+  })
+
+  it('does not overwrite pre-reveal intent after queuing hidden output', async () => {
+    const terminal = { name: 'hidden-streaming-terminal' }
+    const manager = createManager()
+    manager.getPanes.mockReturnValue([{ terminal }])
+    const { syncTerminalScrollIntentFromViewport } = vi.mocked(
+      await import('@/lib/pane-manager/terminal-scroll-intent')
+    )
+    const { flushTerminalOutput } = vi.mocked(
+      await import('@/lib/pane-manager/pane-terminal-output-scheduler')
+    )
+
+    resumeTerminalVisibility(resumeArgs(manager, false))
+
+    expect(flushTerminalOutput).toHaveBeenCalledOnce()
+    expect(syncTerminalScrollIntentFromViewport).toHaveBeenCalledOnce()
+    expect(syncTerminalScrollIntentFromViewport.mock.invocationCallOrder[0]).toBeLessThan(
+      flushTerminalOutput.mock.invocationCallOrder[0] ?? Number.POSITIVE_INFINITY
+    )
+  })
+
   it('resets each pane linkifier hover cache on window wake recovery so links recover without a scroll', () => {
     const first = { name: 'pane-a' }
     const second = { name: 'pane-b' }
diff --git a/src/renderer/src/components/terminal-pane/terminal-visibility-resume.ts b/src/renderer/src/components/terminal-pane/terminal-visibility-resume.ts
index 641c99258bc..5c6b8314545 100644
--- a/src/renderer/src/components/terminal-pane/terminal-visibility-resume.ts
+++ b/src/renderer/src/components/terminal-pane/terminal-visibility-resume.ts
@@ -143,6 +143,8 @@ export function recoverVisibleTerminalWindowWake({
 }: RecoverVisibleTerminalWindowWakeArgs): void {
   // Why: macOS screensaver/display wake can leave xterm visible but with a
   // stale renderer/input surface; Orca's own hidden-state resume never runs.
+  // Why: backlog writes can expose transient viewport geometry while parsing.
+  syncTerminalViewportIntents(manager)
   for (const pane of manager.getPanes()) {
     requestTerminalBacklogRecovery(pane.terminal)
     flushTerminalOutput(pane.terminal, { maxChars: WINDOW_WAKE_FLUSH_CHARS })
@@ -154,7 +156,6 @@ export function recoverVisibleTerminalWindowWake({
       resetTerminalLinkifierHoverState(pane.terminal)
     }
   }
-  syncTerminalViewportIntents(manager)
   manager.resumeRendering()
   // Why: wake re-attaches WebGL — same transient cell-metric wobble guard as the heavy resume.
   manager.fitAllRevealedPanes()
@@ -192,7 +193,7 @@ function resumeTerminalVisibilityHeavy(manager: PaneManager, isActive: boolean):
     requestTerminalBacklogRecovery(pane.terminal)
     flushTerminalOutput(pane.terminal, { maxChars: VISIBLE_RESUME_FLUSH_CHARS })
   }
-  syncTerminalViewportIntents(manager)
+  // Intent was latched by the caller before queued writes can expose transient geometry.
   // Resume WebGL immediately so the terminal shows its last-known state
   // on the first painted frame. macOS context creation is ~5 ms; on
   // Windows (ANGLE -> D3D11) it can be 100-500 ms but a deferred resume
diff --git a/src/renderer/src/hooks/useIpcEvents.test.ts b/src/renderer/src/hooks/useIpcEvents.test.ts
index 1d956f716cb..0b7ea6ad0af 100644
--- a/src/renderer/src/hooks/useIpcEvents.test.ts
+++ b/src/renderer/src/hooks/useIpcEvents.test.ts
@@ -1077,6 +1077,11 @@ describe('useIpcEvents browser tab create routing', () => {
 
     expect(acquireBrowserAutomationVisibility).toHaveBeenCalledWith('page-new')
     expect(acquireBrowserAutomationVisibility).not.toHaveBeenCalledWith('page-active')
+    expect(state.createBrowserTab).toHaveBeenCalledWith(
+      'wt-1',
+      'https://example.com',
+      expect.objectContaining({ allowWindowClose: true })
+    )
     expect(replyTabCreate).toHaveBeenCalledWith({
       requestId: 'req-create',
       browserPageId: 'page-new'
diff --git a/src/renderer/src/hooks/useIpcEvents.ts b/src/renderer/src/hooks/useIpcEvents.ts
index 3c8b19068c2..2a72aae4918 100644
--- a/src/renderer/src/hooks/useIpcEvents.ts
+++ b/src/renderer/src/hooks/useIpcEvents.ts
@@ -2266,6 +2266,7 @@ export function useIpcEvents(): void {
           // Agent/automation opens stay in the background (activate:false) in the active browser group.
           const workspace = store.createBrowserTab(worktreeId, data.url, {
             title: data.url,
+            allowWindowClose: true,
             targetGroupId: data.activate ? undefined : activeBrowserUnifiedTab?.groupId,
             sessionProfileId: data.sessionProfileId,
             sessionPartition: data.sessionPartition,
diff --git a/src/renderer/src/store/slices/browser.ts b/src/renderer/src/store/slices/browser.ts
index 60a71a3eb47..42d0ddbce7b 100644
--- a/src/renderer/src/store/slices/browser.ts
+++ b/src/renderer/src/store/slices/browser.ts
@@ -57,6 +57,7 @@ import { buildValidWorktreeIdsForSessionHydration } from './degraded-repo-worktr
 type CreateBrowserTabOptions = {
   activate?: boolean
   title?: string
+  allowWindowClose?: boolean
   sessionProfileId?: string | null
   sessionPartition?: string | null
   // Place the new tab in a specific group (e.g. "Open Preview to the Side"); defaults to the worktree's active group.
@@ -69,6 +70,7 @@ type CreateBrowserTabOptions = {
 type CreateBrowserPageOptions = {
   activate?: boolean
   title?: string
+  allowWindowClose?: boolean
   browserRuntimeEnvironmentId?: string | null
 }
 
@@ -341,7 +343,8 @@ function buildBrowserPage(
   worktreeId: string,
   url: string,
   title?: string,
-  browserRuntimeEnvironmentId?: string | null
+  browserRuntimeEnvironmentId?: string | null,
+  allowWindowClose?: boolean
 ): BrowserPage {
   const normalizedUrl = normalizeUrl(url)
   return {
@@ -357,6 +360,7 @@ function buildBrowserPage(
     canGoForward: false,
     loadError: null,
     createdAt: Date.now(),
+    ...(allowWindowClose !== undefined ? { allowWindowClose } : {}),
     ...(browserRuntimeEnvironmentId !== undefined ? { browserRuntimeEnvironmentId } : {})
   }
 }
@@ -554,7 +558,8 @@ export const createBrowserSlice: StateCreator<AppState, [], [], BrowserSlice> =
       worktreeId,
       url,
       options?.title,
-      options?.browserRuntimeEnvironmentId
+      options?.browserRuntimeEnvironmentId,
+      options?.allowWindowClose
     )
     // Why: with no explicit profile, inherit the user's default so a Settings preference applies to new tabs.
     const sessionProfileId =
@@ -902,13 +907,15 @@ export const createBrowserSlice: StateCreator<AppState, [], [], BrowserSlice> =
       activate: true,
       sessionProfileId,
       sessionPartition,
-      browserRuntimeEnvironmentId: firstPage.browserRuntimeEnvironmentId
+      browserRuntimeEnvironmentId: firstPage.browserRuntimeEnvironmentId,
+      allowWindowClose: firstPage.allowWindowClose
     })
 
     for (const p of restPages) {
       get().createBrowserPage(restored.id, p.url, {
         activate: false,
         title: p.title,
+        allowWindowClose: p.allowWindowClose,
         browserRuntimeEnvironmentId: p.browserRuntimeEnvironmentId
       })
     }
@@ -987,7 +994,8 @@ export const createBrowserSlice: StateCreator<AppState, [], [], BrowserSlice> =
       workspace.worktreeId,
       url,
       options?.title,
-      options?.browserRuntimeEnvironmentId
+      options?.browserRuntimeEnvironmentId,
+      options?.allowWindowClose
     )
 
     set((s) => {
@@ -1169,6 +1177,7 @@ export const createBrowserSlice: StateCreator<AppState, [], [], BrowserSlice> =
     return get().createBrowserPage(workspaceId, pageToRestore.url, {
       title: pageToRestore.title,
       activate: true,
+      allowWindowClose: pageToRestore.allowWindowClose,
       browserRuntimeEnvironmentId: pageToRestore.browserRuntimeEnvironmentId
     })
   },
diff --git a/src/shared/browser-window-close-policy.ts b/src/shared/browser-window-close-policy.ts
new file mode 100644
index 00000000000..2ea28169ee7
--- /dev/null
+++ b/src/shared/browser-window-close-policy.ts
@@ -0,0 +1,2 @@
+// Why: this marker carries the CLI's explicit close policy across <webview> attach before the guest exists.
+export const BROWSER_WINDOW_CLOSE_ALLOWED_PRELOAD = 'file:///__orca_window_close_allowed__'
diff --git a/src/shared/types.ts b/src/shared/types.ts
index 475470dd4c4..a03c2420985 100644
--- a/src/shared/types.ts
+++ b/src/shared/types.ts
@@ -982,6 +982,8 @@ export type BrowserPage = {
   canGoForward: boolean
   loadError: BrowserLoadError | null
   createdAt: number
+  // Why: CLI-created pages retain Chromium's native window.close behavior; ordinary embedded pages are guarded.
+  allowWindowClose?: boolean
   // Why: remote-owned worktrees can still host client-local fallback browser
   // pages until headless remote runtimes support real browser panes.
   browserRuntimeEnvironmentId?: string | null
diff --git a/src/shared/workspace-session-schema.ts b/src/shared/workspace-session-schema.ts
index da5fe4ef08e..f5d849d5270 100644
--- a/src/shared/workspace-session-schema.ts
+++ b/src/shared/workspace-session-schema.ts
@@ -225,6 +225,7 @@ const browserPageSchema = z.object({
   canGoForward: z.boolean(),
   loadError: browserLoadErrorSchema.nullable(),
   createdAt: z.number(),
+  allowWindowClose: z.boolean().optional(),
   // Why: explicit null marks a browser page as client-local even when its
   // worktree is remote-owned; older sessions omit it and keep inferred runtime.
   browserRuntimeEnvironmentId: z.string().nullable().optional(),
diff --git a/tests/e2e/browser-tab.spec.ts b/tests/e2e/browser-tab.spec.ts
index 7ac10558047..bc8dd51e988 100644
--- a/tests/e2e/browser-tab.spec.ts
+++ b/tests/e2e/browser-tab.spec.ts
@@ -29,10 +29,11 @@ async function createBrowserTab(
   page: Parameters<typeof getActiveWorktreeId>[0],
   worktreeId: string,
   url?: string,
-  title = 'New Browser Tab'
+  title = 'New Browser Tab',
+  allowWindowClose?: boolean
 ): Promise<CreatedBrowserTab | null> {
   return page.evaluate(
-    ({ targetWorktreeId, targetUrl, targetTitle }) => {
+    ({ targetWorktreeId, targetUrl, targetTitle, allowClose }) => {
       const store = window.__store
       if (!store) {
         return null
@@ -44,12 +45,18 @@ async function createBrowserTab(
         targetUrl ?? state.browserDefaultUrl ?? 'about:blank',
         {
           title: targetTitle,
-          activate: true
+          activate: true,
+          allowWindowClose: allowClose
         }
       )
       return { id: tab.id, pageId: tab.activePageId ?? null }
     },
-    { targetWorktreeId: worktreeId, targetUrl: url, targetTitle: title }
+    {
+      targetWorktreeId: worktreeId,
+      targetUrl: url,
+      targetTitle: title,
+      allowClose: allowWindowClose
+    }
   )
 }
 
@@ -199,6 +206,71 @@ async function startBrowserLinkServer(): Promise<{
   }
 }
 
+async function startBrowserWindowCloseServer(): Promise<{
+  url: string
+  sourceUrl: string
+  close: () => Promise<void>
+}> {
+  const server = createServer((request, response) => {
+    const origin = `http://127.0.0.1:${(server.address() as AddressInfo).port}`
+    const pathname = new URL(request.url ?? '/', origin).pathname
+    response.writeHead(200, { 'Content-Type': 'text/html; charset=utf-8' })
+    if (pathname === '/source') {
+      response.end(`
+        <!doctype html>
+        <html>
+          <head><title>Close link source</title></head>
+          <body><a id="window-close-link" href="${origin}/window-close" target="_blank">Open close page</a></body>
+        </html>
+      `)
+      return
+    }
+    response.end(`
+      <!doctype html>
+      <html>
+        <head><title>Window close repro</title></head>
+        <body>
+          <p id="s">Attempting close…</p>
+          <script>
+            window.close()
+            setTimeout(() => {
+              document.getElementById('s').textContent =
+                'window.close() was blocked (expected).'
+            }, 200)
+          </script>
+        </body>
+      </html>
+    `)
+  })
+  await new Promise<void>((resolve) => server.listen(0, '127.0.0.1', resolve))
+  const port = (server.address() as AddressInfo).port
+  return {
+    url: `http://127.0.0.1:${port}/window-close`,
+    sourceUrl: `http://127.0.0.1:${port}/source`,
+    close: () => closeServer(server)
+  }
+}
+
+async function readBrowserWindowCloseStatus(
+  page: Parameters<typeof getActiveWorktreeId>[0],
+  browserTabId: string
+): Promise<string> {
+  return page.evaluate(async (targetBrowserTabId) => {
+    const slot = document.querySelector(`[data-browser-overlay-tab-id="${targetBrowserTabId}"]`)
+    const webview = slot?.querySelector('webview') as Electron.WebviewTag | null
+    if (!webview) {
+      return 'webview missing'
+    }
+    try {
+      return (await webview.executeJavaScript(
+        'document.querySelector("#s")?.textContent ?? "status missing"'
+      )) as string
+    } catch {
+      return 'guest lost'
+    }
+  }, browserTabId)
+}
+
 async function closeServer(server: Server): Promise<void> {
   await new Promise<void>((resolve, reject) =>
     server.close((error) => {
@@ -689,6 +761,88 @@ test.describe('Browser Tab', () => {
     }
   })
 
+  test('blocked window.close in a link-created tab does not break tab switching', async ({
+    orcaPage
+  }) => {
+    const closeServer = await startBrowserWindowCloseServer()
+    try {
+      const worktreeId = (await getActiveWorktreeId(orcaPage))!
+      const neighboringTab = await createBrowserTab(
+        orcaPage,
+        worktreeId,
+        'about:blank',
+        'Neighboring tab'
+      )
+      const sourceTab = await createBrowserTab(
+        orcaPage,
+        worktreeId,
+        closeServer.sourceUrl,
+        'Close link source'
+      )
+      expect(neighboringTab?.id).toBeTruthy()
+      expect(sourceTab?.id).toBeTruthy()
+
+      await clickBrowserLink(orcaPage, sourceTab!.id, '#window-close-link')
+      let closeTabId: string | null = null
+      await expect
+        .poll(async () => {
+          const tabs = await getBrowserTabs(orcaPage, worktreeId)
+          closeTabId = tabs.find((tab) => tab.url === closeServer.url)?.id ?? null
+          return closeTabId
+        })
+        .not.toBeNull()
+
+      await orcaPage.locator(`[data-tab-id="${neighboringTab!.id}"]`).click()
+      await expect.poll(async () => getActiveTabType(orcaPage), { timeout: 5_000 }).toBe('browser')
+      await expect
+        .poll(() => readBrowserWindowCloseStatus(orcaPage, closeTabId!), { timeout: 5_000 })
+        .toContain('window.close() was blocked')
+    } finally {
+      await closeServer.close()
+    }
+  })
+
+  test('explicitly allowed browser tabs retain replaceable window.close', async ({ orcaPage }) => {
+    const closeServer = await startBrowserWindowCloseServer()
+    try {
+      const worktreeId = (await getActiveWorktreeId(orcaPage))!
+      const allowedTab = await createBrowserTab(
+        orcaPage,
+        worktreeId,
+        closeServer.sourceUrl,
+        'Allowed close tab',
+        true
+      )
+      expect(allowedTab?.id).toBeTruthy()
+
+      await expect
+        .poll(
+          () =>
+            orcaPage.evaluate(async (targetBrowserTabId) => {
+              const slot = document.querySelector(
+                `[data-browser-overlay-tab-id="${targetBrowserTabId}"]`
+              )
+              const webview = slot?.querySelector('webview') as Electron.WebviewTag | null
+              if (!webview) {
+                return 'webview missing'
+              }
+              try {
+                return (await webview.executeJavaScript(`(() => {
+                  window.close = () => 'replacement-called'
+                  return window.close() === 'replacement-called' ? 'replacement-called' : 'blocked'
+                })()`)) as string
+              } catch {
+                return 'guest unavailable'
+              }
+            }, allowedTab!.id),
+          { timeout: 5_000 }
+        )
+        .toBe('replacement-called')
+    } finally {
+      await closeServer.close()
+    }
+  })
+
   /**
    * User Prompt:
    * - Browser works and also retains state when switching tabs etc.
diff --git a/tests/e2e/terminal-streaming-refocus-viewport.spec.ts b/tests/e2e/terminal-streaming-refocus-viewport.spec.ts
new file mode 100644
index 00000000000..8376a3188a0
--- /dev/null
+++ b/tests/e2e/terminal-streaming-refocus-viewport.spec.ts
@@ -0,0 +1,240 @@
+import path from 'node:path'
+import type { Page } from '@stablyai/playwright-test'
+import { expect, test } from './helpers/orca-app'
+import { ensureTerminalVisible, waitForActiveWorktree, waitForSessionReady } from './helpers/store'
+import {
+  execInTerminal,
+  getTerminalContent,
+  waitForActivePaneHookDescriptor,
+  waitForActivePanePtyId,
+  waitForActiveTerminalManager
+} from './helpers/terminal'
+import { waitForTerminalPtyDataInjector } from './helpers/terminal-pty-injection'
+import { nodeTerminalCommand } from './terminal-node-command'
+
+const STREAMING_FIXTURE_PATH = path.join(
+  process.cwd(),
+  'tests/e2e/fixtures/streaming-scrollback-fixture.cjs'
+)
+
+type RevealFrame = {
+  targetPresented: boolean
+  thumbTop: number | null
+  maxThumbTop: number | null
+}
+
+async function closeFeatureTips(page: Page): Promise<void> {
+  await page.evaluate(() => {
+    const store = window.__store
+    store?.getState().markFeatureTipsSeen(['orca-cli', 'cmd-j-palette', 'voice-dictation'])
+    if (store?.getState().activeModal === 'feature-tips') {
+      store.getState().closeModal()
+    }
+  })
+}
+
+async function waitForPhaseOneAtBottom(page: Page, tabId: string): Promise<void> {
+  await expect
+    .poll(
+      () =>
+        page.evaluate((targetTabId) => {
+          const pane = window.__paneManagers?.get(targetTabId)?.getPanes?.()[0]
+          const terminal = pane?.terminal
+          if (!terminal) {
+            return false
+          }
+          const buffer = terminal.buffer.active
+          let containsMarker = false
+          for (let line = buffer.baseY; line < buffer.baseY + terminal.rows; line += 1) {
+            if (buffer.getLine(line)?.translateToString(true).includes('STREAM_PHASE1_DONE')) {
+              containsMarker = true
+              break
+            }
+          }
+          const scrollbar = pane.container.querySelector<HTMLElement>(
+            '.xterm-scrollbar.xterm-vertical'
+          )
+          const thumb = scrollbar?.querySelector<HTMLElement>('.xterm-slider') ?? null
+          return Boolean(
+            buffer.baseY > 0 &&
+            buffer.viewportY === buffer.baseY &&
+            containsMarker &&
+            scrollbar &&
+            thumb &&
+            scrollbar.clientHeight - thumb.offsetHeight > 1 &&
+            Math.abs(scrollbar.clientHeight - thumb.offsetHeight - thumb.offsetTop) <= 2
+          )
+        }, tabId),
+      {
+        timeout: 30_000,
+        message: 'phase-one output did not render with the visible viewport at the bottom'
+      }
+    )
+    .toBe(true)
+}
+
+async function injectQueuedWriteAndRefocus(
+  page: Page,
+  tabId: string,
+  paneKey: string
+): Promise<void> {
+  await page.evaluate(
+    ({ targetTabId, paneKey }) => {
+      const pane = window.__paneManagers?.get(targetTabId)?.getPanes?.()[0]
+      if (!pane) {
+        throw new Error('Hidden terminal pane unavailable')
+      }
+      const terminal = pane.terminal
+      // Why: fail loudly if xterm moves the private buffer path that models this wobble.
+      const bufferService = (
+        terminal as typeof terminal & {
+          _core?: {
+            _bufferService?: { buffer?: { ydisp: number }; isUserScrolling: boolean }
+          }
+        }
+      )._core?._bufferService
+      const internalBuffer = bufferService?.buffer
+      if (!internalBuffer || !bufferService) {
+        throw new Error('xterm internal buffer unavailable')
+      }
+      const originalWrite = terminal.write
+      let wobbleApplied = false
+      terminal.write = ((data: string, callback?: () => void) => {
+        terminal.write = originalWrite
+        wobbleApplied = true
+        internalBuffer.ydisp = 0
+        bufferService.isUserScrolling = true
+        if (terminal.buffer.active.viewportY !== 0) {
+          throw new Error('xterm viewport wobble was not observable')
+        }
+        originalWrite.call(terminal, data, callback)
+      }) as typeof terminal.write
+      const injector = (
+        window as Window & {
+          __terminalPtyDataInjection?: {
+            inject: (paneKey: string, data: string) => boolean
+          }
+        }
+      ).__terminalPtyDataInjection
+      const rows = Array.from(
+        { length: 400 },
+        (_, index) => `REFOCUS_STREAM_ROW_${String(index).padStart(4, '0')}_${'x'.repeat(80)}\n`
+      ).join('')
+      if (!injector?.inject(paneKey, `${rows}REFOCUS_STREAM_DONE\n`)) {
+        throw new Error('PTY data injector unavailable')
+      }
+      // Why: focus recovery must flush through terminal.write in this synchronous dispatch.
+      window.dispatchEvent(new Event('focus'))
+      if (!wobbleApplied) {
+        throw new Error('refocus did not flush the queued xterm write')
+      }
+    },
+    { targetTabId: tabId, paneKey }
+  )
+}
+
+async function sampleRevealFrames(page: Page, targetTabId: string): Promise<RevealFrame[]> {
+  return page.evaluate(
+    (targetTabId) =>
+      new Promise<RevealFrame[]>((resolve) => {
+        const frames: RevealFrame[] = []
+        const startedAt = performance.now()
+        const isPresented = (element: Element | null): boolean => {
+          if (!(element instanceof HTMLElement)) {
+            return false
+          }
+          for (
+            let current: HTMLElement | null = element;
+            current;
+            current = current.parentElement
+          ) {
+            const style = getComputedStyle(current)
+            if (
+              style.display === 'none' ||
+              style.visibility === 'hidden' ||
+              style.opacity === '0'
+            ) {
+              return false
+            }
+          }
+          const rect = element.getBoundingClientRect()
+          return (
+            rect.width > 0 &&
+            rect.height > 0 &&
+            rect.right > 0 &&
+            rect.bottom > 0 &&
+            rect.left < window.innerWidth &&
+            rect.top < window.innerHeight
+          )
+        }
+        const sample = (): void => {
+          const pane = window.__paneManagers?.get(targetTabId)?.getPanes?.()[0]
+          const targetXterm = pane?.container.querySelector('.xterm') ?? null
+          const scrollbar =
+            targetXterm?.querySelector<HTMLElement>('.xterm-scrollbar.xterm-vertical') ?? null
+          const thumb = scrollbar?.querySelector<HTMLElement>('.xterm-slider') ?? null
+          frames.push({
+            targetPresented: isPresented(targetXterm),
+            thumbTop: thumb?.offsetTop ?? null,
+            maxThumbTop: scrollbar && thumb ? scrollbar.clientHeight - thumb.offsetHeight : null
+          })
+          if (performance.now() - startedAt >= 700) {
+            resolve(frames)
+            return
+          }
+          requestAnimationFrame(sample)
+        }
+        sample()
+      }),
+    targetTabId
+  )
+}
+
+test.describe('terminal streaming refocus viewport', () => {
+  test('keeps follow-output at the bottom through a queued-write refocus wobble', async ({
+    orcaPage
+  }) => {
+    await waitForSessionReady(orcaPage)
+    await closeFeatureTips(orcaPage)
+    await waitForActiveWorktree(orcaPage)
+    await ensureTerminalVisible(orcaPage)
+    await waitForActiveTerminalManager(orcaPage, 30_000)
+    const ptyId = await waitForActivePanePtyId(orcaPage)
+    const { paneKey } = await waitForActivePaneHookDescriptor(orcaPage)
+    const tabId = paneKey.slice(0, paneKey.indexOf(':'))
+    await waitForTerminalPtyDataInjector(orcaPage, paneKey)
+    await execInTerminal(orcaPage, ptyId, nodeTerminalCommand([STREAMING_FIXTURE_PATH]))
+    await waitForPhaseOneAtBottom(orcaPage, tabId)
+
+    const framesPromise = sampleRevealFrames(orcaPage, tabId)
+    await injectQueuedWriteAndRefocus(orcaPage, tabId, paneKey)
+    const frames = await framesPromise
+
+    expect(frames.filter((frame) => !frame.targetPresented)).toEqual([])
+    expect(
+      frames.filter(
+        (frame) =>
+          frame.thumbTop === null ||
+          frame.maxThumbTop === null ||
+          Math.abs(frame.maxThumbTop - frame.thumbTop) > 2
+      )
+    ).toEqual([])
+    expect(frames.some((frame) => (frame.maxThumbTop ?? 0) > 1)).toBe(true)
+    expect(
+      frames.filter((frame) => (frame.maxThumbTop ?? 0) > 1 && (frame.thumbTop ?? 0) <= 1)
+    ).toEqual([])
+    await expect
+      .poll(() => getTerminalContent(orcaPage), { timeout: 15_000 })
+      .toContain('REFOCUS_STREAM_DONE')
+    const visibleScrollbar = orcaPage.locator('.xterm-scrollbar.xterm-vertical:visible').first()
+    await expect(visibleScrollbar).toBeVisible()
+    expect(
+      await visibleScrollbar.evaluate((scrollbar) => {
+        const thumb = scrollbar.querySelector<HTMLElement>('.xterm-slider')
+        return Boolean(
+          thumb && Math.abs(scrollbar.clientHeight - thumb.offsetHeight - thumb.offsetTop) <= 2
+        )
+      })
+    ).toBe(true)
+  })
+})