diff --git a/.github/workflows/pr.yml b/.github/workflows/pr.yml
index ca1651325c9..a749214e232 100644
--- a/.github/workflows/pr.yml
+++ b/.github/workflows/pr.yml
@@ -807,6 +807,7 @@ jobs:
           src/main/agent-hooks/windows-hook-payload-delivery.test.ts
           src/main/windows/windows-pty-job.win32.test.ts
           src/main/windows/windows-host-job.win32.test.ts
+          src/main/windows-live-tree-kill.win32.test.ts
           src/main/wsl/wsl-runner.test.ts
           src/main/wsl/wsl-guest-environment.test.ts
           src/main/wsl/wsl-invocation-boundary.test.ts
diff --git a/config/scripts/pr-code-change-scope.mjs b/config/scripts/pr-code-change-scope.mjs
index f5a73f6239f..15ded915c67 100644
--- a/config/scripts/pr-code-change-scope.mjs
+++ b/config/scripts/pr-code-change-scope.mjs
@@ -219,6 +219,7 @@ const WINDOWS_PACKAGE_TESTS = [
   'src/main/agent-hooks/windows-hook-payload-delivery.test.ts',
   'src/main/windows/windows-pty-job.win32.test.ts',
   'src/main/windows/windows-host-job.win32.test.ts',
+  'src/main/windows-live-tree-kill.win32.test.ts',
   'src/main/wsl/wsl-runner.test.ts',
   'src/main/wsl/wsl-guest-environment.test.ts',
   'src/main/wsl/wsl-invocation-boundary.test.ts',
diff --git a/src/main/__fixtures__/shell-wrapper-snapshots/daemon-bash-rcfile.txt b/src/main/__fixtures__/shell-wrapper-snapshots/daemon-bash-rcfile.txt
index 54837bf4d65..b79ed543494 100644
--- a/src/main/__fixtures__/shell-wrapper-snapshots/daemon-bash-rcfile.txt
+++ b/src/main/__fixtures__/shell-wrapper-snapshots/daemon-bash-rcfile.txt
@@ -127,10 +127,6 @@ __orca_osc133_precmd() {
     unset __orca_in_command
   fi
   printf "\033]133;A\007"
-  # Why: emit the shell-ready marker here (not a trailing PROMPT_COMMAND entry)
-  # so a framework that must be last in PROMPT_COMMAND — bash-preexec — is not
-  # displaced by one of Orca's own hooks.
-  [[ -n "$__orca_ready_marker" ]] && printf "\033]777;orca-shell-ready\007"
   return "$exit_code"
 }
 __orca_osc133_preexec() {
@@ -188,6 +184,11 @@ __orca_osc133_epilogue() {
   unset __orca_in_prompt_command
   __orca_adopt_outer_debug_trap
   trap '__orca_osc133_preexec' DEBUG
+  # Readline renders PS1 after entering raw mode; prompt hooks still run in cooked mode.
+  if [[ -n "$__orca_ready_marker" ]]; then
+    PS1="${PS1-}"'\[\e]777;orca-shell-ready\a\]'
+    __orca_ready_marker=""
+  fi
 }
 __orca_normalize_prompt_command_part() {
   local __orca_value="$1" __orca_output_name="$2" __orca_character __orca_chunk
diff --git a/src/main/automations/precheck-runner.ts b/src/main/automations/precheck-runner.ts
index 753bd784b06..ab38fd42355 100644
--- a/src/main/automations/precheck-runner.ts
+++ b/src/main/automations/precheck-runner.ts
@@ -4,6 +4,7 @@ import type { AutomationPrecheck, AutomationPrecheckResult } from '../../shared/
 import { MAX_AUTOMATION_PRECHECK_OUTPUT_CHARS } from '../../shared/automation-precheck'
 import { getSshConnectionManager } from '../ipc/ssh'
 import { shellEscape } from '../ssh/ssh-connection-utils'
+import { admitSelfInitiatedTreeKill } from '../own-chromium-tree-kill-guard'
 
 type AutomationPrecheckExecutionTarget =
   | {
@@ -73,7 +74,10 @@ function failedPrecheckResult(
   })
 }
 
-function killLocalPrecheckProcessTree(child: ChildProcess): ReturnType<typeof setTimeout> | null {
+/** Exported for the refusal-fallback test; the timeout path is otherwise unreachable. */
+export function killLocalPrecheckProcessTree(
+  child: ChildProcess
+): ReturnType<typeof setTimeout> | null {
   const pid = child.pid
   if (!pid) {
     child.kill()
@@ -81,6 +85,18 @@ function killLocalPrecheckProcessTree(child: ChildProcess): ReturnType<typeof se
   }
 
   if (process.platform === 'win32') {
+    if (
+      !admitSelfInitiatedTreeKill({
+        pid,
+        site: 'automation-precheck-timeout',
+        scope: 'win-taskkill-tree'
+      })
+    ) {
+      // Refusal blocks the tree walk, not the termination: killing the root by
+      // handle cannot reach a recycled pid, and a timed-out precheck must stop.
+      child.kill()
+      return null
+    }
     try {
       // Why: shell prechecks can launch child processes; taskkill walks the
       // Windows process tree so timeout means the command is actually stopped.
diff --git a/src/main/codex/codex-app-server-session.ts b/src/main/codex/codex-app-server-session.ts
index 2e176e13ae2..35537f59d0d 100644
--- a/src/main/codex/codex-app-server-session.ts
+++ b/src/main/codex/codex-app-server-session.ts
@@ -2,6 +2,7 @@ import { spawn, type ChildProcess, type ChildProcessWithoutNullStreams } from 'n
 import { waitForProcessExitUntil } from './codex-process-exit-deadline'
 import { stderrIndicatesMissingAppServer } from './codex-app-server-capability-signal'
 import { withCliRuntimeOnPath } from '../../shared/node-cli-command-resolution'
+import { admitProcessTreeKill } from '../../shared/child-process/process-tree-kill-gate'
 
 // Why: `codex app-server` is Orca's sanctioned RPC surface into Codex-owned
 // state (hook trust hashes, the sqlite thread index). This module owns the
@@ -74,6 +75,18 @@ export function killCodexAppServerProcessTree(
   const platform = options.platform ?? process.platform
   const spawnImpl = options.spawnImpl ?? spawn
   if (platform === 'win32' && child.pid) {
+    if (
+      !admitProcessTreeKill({
+        pid: child.pid,
+        site: 'codex-app-server-session-deadline',
+        scope: 'win-taskkill-tree'
+      })
+    ) {
+      // Refusal blocks the tree walk, not the termination: the root kill is
+      // handle-addressed, so it cannot reach the recycled pid we refused.
+      child.kill('SIGKILL')
+      return
+    }
     try {
       // Why: npm-installed Codex runs behind cmd.exe; killing only that wrapper
       // leaves the app-server child alive after a timeout or failed shutdown.
diff --git a/src/main/codex/codex-structured-turn-processes.ts b/src/main/codex/codex-structured-turn-processes.ts
index 6bb4b960a1b..163cbb098fb 100644
--- a/src/main/codex/codex-structured-turn-processes.ts
+++ b/src/main/codex/codex-structured-turn-processes.ts
@@ -57,6 +57,8 @@ async function terminateWindowsAddedProcesses(
   const added = current.filter((row) => baseline.get(row.pid) !== windowsIdentity(row))
   const addedPids = new Set(added.map((row) => row.pid))
   const roots = added.filter((row) => !addedPids.has(row.ppid))
+  // Added roots come from a table walk, not a spawn, so a refused tree walk has
+  // no handle to fall back to: the row stays in `remaining` and this reports false.
   await Promise.all(
     roots.map((row) => terminateWindowsProcessTree(row.pid, { site: 'codex-turn-added-roots' }))
   )
diff --git a/src/main/crash-reporting/self-initiated-tree-kill-log.test.ts b/src/main/crash-reporting/self-initiated-tree-kill-log.test.ts
index c57c1796a35..e958dac42f8 100644
--- a/src/main/crash-reporting/self-initiated-tree-kill-log.test.ts
+++ b/src/main/crash-reporting/self-initiated-tree-kill-log.test.ts
@@ -17,17 +17,17 @@ import { recordProcessGoneCrash, type ProcessGoneCrashEvent } from './process-go
 import { resetProcessGoneSiblingCorrelationForTest } from './process-gone-sibling-correlation'
 import {
   findSelfInitiatedTreeKills,
-  installProcessTreeKillBreadcrumbObserver,
   recordRefusedOwnChromiumTreeKill,
   recordSelfInitiatedTreeKill,
   resetSelfInitiatedTreeKillLogForTest,
   selfInitiatedTreeKillDetails
 } from './self-initiated-tree-kill-log'
 import {
-  notifyProcessTreeKill,
-  setProcessTreeKillObserver
-} from '../../shared/child-process/process-tree-kill-observer'
+  admitProcessTreeKill,
+  setProcessTreeKillGate
+} from '../../shared/child-process/process-tree-kill-gate'
 import { terminateWindowsProcessTree } from '../windows-process-tree-kill'
+import { installMainProcessTreeKillGate } from '../own-chromium-tree-kill-guard'
 import { _resetTracerForTests, setActiveSink } from '../observability/tracer'
 
 /** The field shape: renderer, `reason=killed exitCode=1`, win32 (#G2). */
@@ -252,12 +252,90 @@ describe('self-initiated tree kill breadcrumb', () => {
     expect(String(details.selfInitiatedKills)).toContain('more)')
   })
 
-  it('records a kill issued through the shared runProcess choke point', () => {
-    installProcessTreeKillBreadcrumbObserver()
+  it('keeps the pid-addressed kill when a window-close burst overruns the ring', () => {
+    // Review probe: one taskkill, then 32 routine Job Object teardowns. Under
+    // plain FIFO the discriminating entry is evicted and the persisted detail
+    // becomes byte-identical to the external-kill arm.
+    const goneAt = 5_000_000
+    recordSelfInitiatedTreeKill({
+      pid: 4242,
+      site: 'pty-descendant-sweep',
+      scope: 'win-taskkill-tree',
+      at: goneAt - 4_000
+    })
+    for (let index = 0; index < 32; index += 1) {
+      recordSelfInitiatedTreeKill({
+        pid: 6000 + index,
+        site: 'windows-pty-job-teardown',
+        scope: 'win-pty-job',
+        at: goneAt - 100
+      })
+    }
 
-    notifyProcessTreeKill({ pid: 3131, site: 'run-process-tree', scope: 'posix-process-group' })
+    const details = selfInitiatedTreeKillDetails(goneAt)
+
+    expect(details.selfInitiatedTreeKillCount).toBe(1)
+    expect(details.selfInitiatedGroupKillCount).toBe(31)
+    expect(String(details.selfInitiatedKills)).toMatch(
+      /^win-taskkill-tree\/pty-descendant-sweep\/pid4242 -4000ms/
+    )
+  })
+
+  it('keeps the newest teardown when a session has saturated the ring with pid kills', () => {
+    // Review probe, the mirror of the case above: 32 session-old taskkills (six
+    // routine families feed them) then the Job Object teardown 50ms before the
+    // death. A scope-preference eviction with no floor splices the entry it just
+    // pushed, and `{}` is byte-identical to the external-kill arm.
+    const goneAt = 5_000_000
+    for (let index = 0; index < 32; index += 1) {
+      recordSelfInitiatedTreeKill({
+        pid: 6000 + index,
+        site: 'pty-descendant-sweep',
+        scope: 'win-taskkill-tree',
+        at: goneAt - 600_000 + index * 1_000
+      })
+    }
+    recordSelfInitiatedTreeKill({
+      pid: 7777,
+      site: 'windows-pty-job-teardown',
+      scope: 'win-pty-job',
+      at: goneAt - 50
+    })
+
+    const details = selfInitiatedTreeKillDetails(goneAt)
+
+    expect(details.selfInitiatedGroupKillCount).toBe(1)
+    expect(String(details.selfInitiatedKills)).toContain(
+      'win-pty-job/windows-pty-job-teardown/pid7777 -50ms'
+    )
+  })
+
+  it('evicts the oldest pid kill, not the newest, once every candidate is pid-addressed', () => {
+    const goneAt = 5_000_000
+    for (let index = 0; index < 33; index += 1) {
+      recordSelfInitiatedTreeKill({
+        pid: 6000 + index,
+        site: 'git-command-tree-kill',
+        scope: 'win-taskkill-tree',
+        at: goneAt - 1_000
+      })
+    }
+
+    const pids = findSelfInitiatedTreeKills(goneAt).map((kill) => kill.pid)
+
+    expect(pids).toHaveLength(32)
+    expect(pids).toContain(6032)
+    expect(pids).not.toContain(6000)
+  })
+
+  it('records a kill issued through the shared runProcess choke point', () => {
+    installMainProcessTreeKillGate()
+
+    expect(
+      admitProcessTreeKill({ pid: 3131, site: 'run-process-tree', scope: 'posix-process-group' })
+    ).toBe(true)
 
     expect(findSelfInitiatedTreeKills(Date.now()).map((kill) => kill.pid)).toEqual([3131])
-    setProcessTreeKillObserver(null)
+    setProcessTreeKillGate(null)
   })
 })
diff --git a/src/main/crash-reporting/self-initiated-tree-kill-log.ts b/src/main/crash-reporting/self-initiated-tree-kill-log.ts
index e819795074f..809d421ac61 100644
--- a/src/main/crash-reporting/self-initiated-tree-kill-log.ts
+++ b/src/main/crash-reporting/self-initiated-tree-kill-log.ts
@@ -1,8 +1,5 @@
 import type { CrashReportDetailValue } from '../../shared/crash-reporting'
-import {
-  setProcessTreeKillObserver,
-  type ProcessTreeKillScope
-} from '../../shared/child-process/process-tree-kill-observer'
+import type { ProcessTreeKillScope } from '../../shared/child-process/process-tree-kill-gate'
 import { recordCoalescedDurableCrashBreadcrumb } from './durable-crash-breadcrumb'
 
 /**
@@ -19,24 +16,38 @@ import { recordCoalescedDurableCrashBreadcrumb } from './durable-crash-breadcrum
  * The ring is per-process and its only reader is `process-gone-recorder`, which
  * exists in Electron main. So a count reported on a `render-process-gone` covers
  * kills issued *from Electron main*, and nothing else:
- * - Main only: the three `taskkill /T /F` families that gate on
- *   `admitSelfInitiatedTreeKill` (`terminateWindowsProcessTree` and the codex /
- *   claude account-login teardowns) and the codex app-server POSIX group
+ * - Main only: the families that import the gate directly —
+ *   `terminateWindowsProcessTree`, the codex and claude account-login
+ *   teardowns, the git command-runner abort, the notebook-cell and
+ *   automation-precheck timeouts — plus the codex app-server POSIX group
  *   teardowns.
- * - Main *and* other hosts: `signalProcessTree` (the `runProcess` choke point,
- *   reached from the CLI, relay and daemon too — a fourth pid-addressed
- *   `taskkill` family, gated on the child not being reaped rather than on the
- *   Chromium set it cannot read), the POSIX PTY process-group sweep and the
- *   Windows PTY Job Object (relay `pty-handler`, daemon
- *   `subprocess-handle`). When those run outside main they record into that
- *   process's own ring, which nothing reads — no observer is installed there,
- *   and the tracer sink is a no-op.
- * - Never instrumented: the direct `process.kill(-pid)` calls in the browser
- *   routes, notebooks, automation prechecks and ephemeral-VM recipes.
+ * - Main *and* other hosts, through the `process-tree-kill-gate` seam main
+ *   installs the same guard into: `signalProcessTree` (the `runProcess` choke
+ *   point, reached from the CLI, relay and daemon too), the codex app-server
+ *   deadline kill (compiled into the CLI as well) and the ephemeral-VM recipe
+ *   kill. Also host-spanning but recording directly: the POSIX PTY
+ *   process-group sweep and the Windows PTY Job Object (relay `pty-handler`,
+ *   daemon `subprocess-handle`). When any of these run outside main they record
+ *   into that process's own ring, which nothing reads — no gate is installed
+ *   there, and the tracer sink is a no-op.
+ * - Never instrumented, and none of them a pid-addressed kill issued from main:
+ *   the POSIX `process.kill(-pid, …)` group arms of the notebook, precheck,
+ *   browser-route and ephemeral-VM kills, plus the macOS keyboard-input-source
+ *   probe's group kill in `ipc/app.ts`; the relay's own
+ *   `subprocess-tree-termination` taskkill and the CLI's login-interruption
+ *   taskkill (neither runs in main); and the browser-route Electron probes,
+ *   which are reached only from `*.electron.test.ts`.
+ *
+ * `main-process-tree-kill-gate.test.ts` is the ratchet that keeps that list
+ * closed: it counts `/pid` call sites against gate admissions per file, so a new
+ * pid-addressed kill fails it whether it lands in a new file or inside a family
+ * that already asks the gate. It does not see a `/pid` argument built from a
+ * variable.
  *
  * A daemon or relay kill missing from the count is a diagnostics gap, not a
  * missed suspect: those hosts cannot reach a Chromium pid in the first place
- * (see `orca-chromium-process-pids.ts`). Absence is evidence, not proof.
+ * (see `orca-chromium-process-pids.ts`), and a group or Job-Object kill can
+ * only contain what Orca put in it. Absence is evidence, not proof.
  */
 
 /** Which mechanism issued the kill; each has a different blast radius. */
@@ -81,6 +92,25 @@ function isPidAddressedTreeKill(scope: SelfInitiatedTreeKillScope): boolean {
   return scope === 'win-taskkill-tree'
 }
 
+/**
+ * Drop one entry, newest-first-preserving.
+ *
+ * Two rules, in order. The entry just recorded is never a candidate: it is the
+ * one closest to any death that follows, and evicting it leaves a detail
+ * byte-identical to the external-kill arm. Among the rest, routine group/job
+ * teardown goes before a pid-addressed kill — a window-close burst is 30+ group
+ * kills and plain FIFO would drop the one entry that can explain the death —
+ * falling back to plain FIFO once every candidate is pid-addressed, which is
+ * what an ordinary session saturates the ring with.
+ */
+function evictOneSelfInitiatedTreeKill(): void {
+  const lastCandidate = selfInitiatedKills.length - 1
+  const oldestGroupKill = selfInitiatedKills.findIndex(
+    (kill, index) => index < lastCandidate && !isPidAddressedTreeKill(kill.scope)
+  )
+  selfInitiatedKills.splice(Math.max(oldestGroupKill, 0), 1)
+}
+
 export function recordSelfInitiatedTreeKill({
   pid,
   site,
@@ -96,13 +126,15 @@ export function recordSelfInitiatedTreeKill({
     return
   }
   selfInitiatedKills.push({ pid, site, scope, at })
-  if (selfInitiatedKills.length > MAX_TRACKED_SELF_KILLS) {
-    selfInitiatedKills = selfInitiatedKills.slice(-MAX_TRACKED_SELF_KILLS)
+  while (selfInitiatedKills.length > MAX_TRACKED_SELF_KILLS) {
+    evictOneSelfInitiatedTreeKill()
   }
   // Durable so it survives into the diagnostic bundle even when the kill takes
   // the reporting renderer with it; coalesced because the crash detail above is
   // the primary record and a teardown burst must not cost 30 ring slots plus a
-  // forced disk flush each. The newest pid still rides the emitted crumb.
+  // forced disk flush each. The retained ring crumb carries the newest pid, but
+  // the span trail emits only the first of a coalesced burst — read
+  // `selfInitiatedKills` for the rest.
   recordCoalescedDurableCrashBreadcrumb({
     name: 'self_tree_kill',
     data: { pid, site, scope },
@@ -133,11 +165,6 @@ export function recordRefusedOwnChromiumTreeKill(target: {
   })
 }
 
-/** Routes the `runProcess` choke point's kills here; shared code cannot import us. */
-export function installProcessTreeKillBreadcrumbObserver(): void {
-  setProcessTreeKillObserver((kill) => recordSelfInitiatedTreeKill(kill))
-}
-
 export function findSelfInitiatedTreeKills(at: number): SelfInitiatedTreeKill[] {
   return selfInitiatedKills.filter((kill) => {
     const offsetMs = kill.at - at
diff --git a/src/main/daemon/agent-startup-prompt-latency.node-pty.test.ts b/src/main/daemon/agent-startup-prompt-latency.node-pty.test.ts
new file mode 100644
index 00000000000..cfa01fed8e5
--- /dev/null
+++ b/src/main/daemon/agent-startup-prompt-latency.node-pty.test.ts
@@ -0,0 +1,123 @@
+import { appendFileSync, existsSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { createPtySubprocess } from './pty-subprocess'
+import { Session } from './session'
+
+const SHELLS = process.platform === 'win32' ? [] : ['/bin/bash', '/bin/zsh'].filter(existsSync)
+const COMMAND = "printf 'AGENT_%s\\n' STARTED"
+
+async function launch(
+  shell: string,
+  slow: boolean,
+  legacy = false
+): Promise<{ output: string; ms: number }> {
+  const root = mkdtempSync(join(tmpdir(), 'orca-startup-latency-'))
+  const bash = shell.endsWith('bash')
+  const pause = slow ? 'sleep 0.6\n' : ''
+  const prompt = slow ? "PS1='$(sleep 0.3)prompt> '\n" : "PS1='prompt> '\n"
+  writeFileSync(
+    join(root, bash ? '.bash_profile' : '.zshrc'),
+    `${pause}${bash ? '' : 'setopt PROMPT_SUBST\n'}${prompt}`
+  )
+  vi.stubEnv('HOME', root)
+  vi.stubEnv('ZDOTDIR', root)
+  vi.stubEnv('ORCA_ORIG_ZDOTDIR', root)
+  let session: Session | undefined
+  let timer: ReturnType<typeof setTimeout> | undefined
+  let legacyTimer: ReturnType<typeof setTimeout> | undefined
+  const readinessEvents: string[] = []
+  const started = performance.now()
+  try {
+    const subprocess = await createPtySubprocess({
+      sessionId: 'startup-latency',
+      cols: 120,
+      rows: 30,
+      cwd: root,
+      shellOverride: shell,
+      command: COMMAND,
+      env: { HOME: root, SHELL: shell, TERM: 'xterm-256color' }
+    })
+    session = new Session({
+      sessionId: 'startup-latency',
+      cols: 120,
+      rows: 30,
+      subprocess,
+      shellReadySupported: !legacy,
+      reportReadinessEvent: (event) => readinessEvents.push(event)
+    })
+    const active = session
+    return await new Promise((resolve, reject) => {
+      let output = ''
+      timer = setTimeout(
+        () => reject(new Error(`Startup timed out: ${JSON.stringify(output)}`)),
+        5000
+      )
+      active.attachClient({
+        onExit: () => {},
+        onData: (data) => {
+          output += data
+          if (output.includes('AGENT_STARTED')) {
+            resolve({ output, ms: performance.now() - started })
+          }
+        }
+      })
+      if (legacy) {
+        legacyTimer = setTimeout(() => active.write(`${COMMAND}\n`), 300)
+      } else {
+        active.write(`${COMMAND}\n`)
+      }
+    })
+  } finally {
+    clearTimeout(timer)
+    clearTimeout(legacyTimer)
+    if (session) {
+      await session.forceKillAndWaitForExit(3000)
+      session.dispose()
+    }
+    vi.unstubAllEnvs()
+    rmSync(root, { recursive: true, force: true })
+    expect(readinessEvents).toEqual([])
+  }
+}
+
+describe('agent startup at the rendered shell prompt', () => {
+  afterEach(() => vi.unstubAllEnvs())
+  it.each(SHELLS)(
+    '%s displays the command once after slow startup and prompt expansion',
+    async (shell) => {
+      const before = await launch(shell, true, true)
+      expect(before.output.split(COMMAND)).toHaveLength(3)
+      const result = await launch(shell, true)
+      expect(result.output).not.toContain('orca-shell-ready')
+      expect(result.output.split(COMMAND)).toHaveLength(2)
+      expect(result.output.indexOf('prompt> ')).toBeLessThan(result.output.indexOf(COMMAND))
+    }
+  )
+
+  it.skipIf(!process.env.ORCA_STARTUP_BENCH || SHELLS.length === 0)(
+    'compares legacy input timing with prompt delivery',
+    async () => {
+      for (const shell of SHELLS) {
+        for (const slow of [false, true]) {
+          const legacy: number[] = []
+          const current: number[] = []
+          for (let i = 0; i < 5; i++) {
+            legacy.push((await launch(shell, slow, true)).ms)
+            const result = await launch(shell, slow)
+            expect(result.output).not.toContain('orca-shell-ready')
+            expect(result.output.split(COMMAND)).toHaveLength(2)
+            current.push(result.ms)
+          }
+          const result = JSON.stringify({ shell, slow, legacy, current })
+          if (process.env.ORCA_STARTUP_BENCH_OUTPUT) {
+            appendFileSync(process.env.ORCA_STARTUP_BENCH_OUTPUT, `${result}\n`)
+          }
+          console.log(result)
+        }
+      }
+    },
+    60_000
+  )
+})
diff --git a/src/main/daemon/daemon-bash-shell-ready-rcfile.ts b/src/main/daemon/daemon-bash-shell-ready-rcfile.ts
index 142c0c131d9..f7834dba9d7 100644
--- a/src/main/daemon/daemon-bash-shell-ready-rcfile.ts
+++ b/src/main/daemon/daemon-bash-shell-ready-rcfile.ts
@@ -2,7 +2,6 @@ import { getPosixOmpShellWrapper } from '../pty/omp-shell-wrapper'
 import { getPosixCodexShellLaunchPreflight } from '../pty/codex-shell-launch-preflight'
 import { BASH_PROMPT_COMMAND_COMPOSITION_BLOCK } from '../bash-prompt-command-composition'
 import { BASH_FEATURE_CHANNEL_BLOCK, SHELL_STARTUP_IDENTITY_MARKER_BLOCK } from '../shell-templates'
-import { SHELL_READY_MARKER } from './daemon-shell-ready-marker'
 
 export function getDaemonBashShellReadyRcfileContent(): string {
   return `# Orca daemon bash shell-ready wrapper
@@ -56,10 +55,6 @@ __orca_osc133_precmd() {
     unset __orca_in_command
   fi
   printf "\\033]133;A\\007"
-  # Why: emit the shell-ready marker here (not a trailing PROMPT_COMMAND entry)
-  # so a framework that must be last in PROMPT_COMMAND — bash-preexec — is not
-  # displaced by one of Orca's own hooks.
-  [[ -n "$__orca_ready_marker" ]] && printf "${SHELL_READY_MARKER}"
   return "$exit_code"
 }
 __orca_osc133_preexec() {
@@ -117,6 +112,11 @@ __orca_osc133_epilogue() {
   unset __orca_in_prompt_command
   __orca_adopt_outer_debug_trap
   trap '__orca_osc133_preexec' DEBUG
+  # Readline renders PS1 after entering raw mode; prompt hooks still run in cooked mode.
+  if [[ -n "$__orca_ready_marker" ]]; then
+    PS1="\${PS1-}"'\\[\\e]777;orca-shell-ready\\a\\]'
+    __orca_ready_marker=""
+  fi
 }
 ${BASH_PROMPT_COMMAND_COMPOSITION_BLOCK}
 __orca_prepend_prompt_command "__orca_osc133_precmd"
diff --git a/src/main/daemon/daemon-pty-adapter.test.ts b/src/main/daemon/daemon-pty-adapter.test.ts
index fc2f9365f23..d0c0198af65 100644
--- a/src/main/daemon/daemon-pty-adapter.test.ts
+++ b/src/main/daemon/daemon-pty-adapter.test.ts
@@ -344,35 +344,32 @@ describe('DaemonPtyAdapter (IPtyProvider)', () => {
       }
     })
 
-    itOnPosix('keeps plain Codex startup on the short daemon shell-ready timeout', async () => {
-      await adapter.spawn({
-        cols: 80,
-        rows: 24,
-        command: 'codex',
-        env: { SHELL: '/bin/zsh' }
-      })
-
+    itOnPosix('preserves the existing fast-start timing for fish', async () => {
+      await adapter.spawn({ cols: 80, rows: 24, command: 'codex', env: { SHELL: '/usr/bin/fish' } })
       await waitFor(() => vi.mocked(lastSubprocess.write).mock.calls.length > 0)
-      expect(lastSubprocess.write).toHaveBeenCalledWith('codex\n')
+      expect(lastSubprocess.write).toHaveBeenCalledExactlyOnceWith('codex\n')
+      expect(lastSpawnOpts).not.toEqual(
+        expect.objectContaining({ startupCommandDelivery: 'shell-ready' })
+      )
     })
 
-    itOnPosix('waits for shell-ready for delivery-hinted Codex startup', async () => {
-      await adapter.spawn({
-        cols: 80,
-        rows: 24,
-        command: "codex 'linked issue context'",
-        startupCommandDelivery: 'shell-ready',
-        env: { SHELL: '/bin/zsh' }
-      })
+    itOnPosix.each([
+      { command: 'codex' },
+      { command: 'codex', startupCommandDelivery: 'fast' as const },
+      { command: "codex 'linked issue context'", startupCommandDelivery: 'shell-ready' as const }
+    ])('waits past 300ms and submits once after readiness: %j', async (startup) => {
+      await adapter.spawn({ cols: 80, rows: 24, ...startup, env: { SHELL: '/bin/zsh' } })
 
       await new Promise((resolve) => setTimeout(resolve, 350))
       expect(lastSubprocess.write).not.toHaveBeenCalled()
-
+      expect(lastSpawnOpts).toEqual(
+        expect.objectContaining({ startupCommandDelivery: 'shell-ready' })
+      )
       lastSubprocess._simulateData('\x1b]777;orca-shell-ready\x07')
       lastSubprocess._simulateData('\r\nuser@host $ ')
 
       await waitFor(() => vi.mocked(lastSubprocess.write).mock.calls.length > 0)
-      expect(lastSubprocess.write).toHaveBeenCalledWith("codex 'linked issue context'\n")
+      expect(lastSubprocess.write).toHaveBeenCalledExactlyOnceWith(`${startup.command}\n`)
     })
   })
 
diff --git a/src/main/daemon/daemon-pty-session-spawn.ts b/src/main/daemon/daemon-pty-session-spawn.ts
index 235b286b0bc..00f19777878 100644
--- a/src/main/daemon/daemon-pty-session-spawn.ts
+++ b/src/main/daemon/daemon-pty-session-spawn.ts
@@ -1,5 +1,6 @@
 import { recognizeAgentProcessFromCommandLine } from '../../shared/agent-process-recognition'
 import { shouldUseShellReadyStartupDelivery } from '../../shared/codex-startup-delivery'
+import { CODEX_SHELL_READY_TIMEOUT_MS } from './session-shell-ready-barrier'
 import type {
   HistoryRecoveryContext,
   PendingDaemonSpawnOperation
@@ -11,8 +12,11 @@ import { DaemonPtySpawnResult } from './daemon-pty-spawn-result'
 import type { DaemonPtySpawnContext } from './daemon-pty-spawn-request'
 import type { ColdRestoreInfo } from './history-reader'
 import { mintPtySessionId } from './pty-session-id'
-import { CODEX_SHELL_READY_TIMEOUT_MS } from './session-shell-ready-barrier'
-import { supportsPtyStartupBarrier } from './shell-ready'
+import {
+  supportsPtyStartupBarrier,
+  shellReadyMarkerComesFromLineEditor,
+  resolvePtyShellPath
+} from './shell-ready'
 import { getRecoveredHistorySeedSegments } from './terminal-history-seed-segments'
 import { AGENT_SESSION_CLAIM_DAEMON_PROTOCOL_VERSION, type CreateOrAttachResult } from './types'
 import { normalizeWslColdRestoreCwd } from './wsl-cold-restore-cwd'
@@ -213,21 +217,23 @@ export abstract class DaemonPtySessionSpawn extends DaemonPtySpawnResult {
     let effectiveRows = restoreInfo?.rows ?? opts.rows
 
     const shellReadySupported = opts.command ? supportsPtyStartupBarrier(opts.env ?? {}) : false
-    const isCodexStartupCommand =
-      recognizeAgentProcessFromCommandLine(opts.command)?.agent === 'codex'
-    const shouldWaitForShellReady =
-      isCodexStartupCommand &&
-      shouldUseShellReadyStartupDelivery({
+    const immediateMarker =
+      process.platform !== 'win32' &&
+      shellReadyMarkerComesFromLineEditor(opts.shellOverride || resolvePtyShellPath(opts.env ?? {}))
+    const shellReadyTimeoutMs =
+      shellReadySupported &&
+      !immediateMarker &&
+      recognizeAgentProcessFromCommandLine(opts.command)?.agent === 'codex' &&
+      !shouldUseShellReadyStartupDelivery({
         command: opts.command,
         startupCommandDelivery: opts.startupCommandDelivery
       })
-    const shellReadyTimeoutMs =
-      shellReadySupported && isCodexStartupCommand && !shouldWaitForShellReady
         ? CODEX_SHELL_READY_TIMEOUT_MS
         : undefined
-
     const context: DaemonPtySpawnContext = {
-      opts,
+      // Older daemons also need the existing hint to enable their ready marker.
+      opts:
+        opts.command && immediateMarker ? { ...opts, startupCommandDelivery: 'shell-ready' } : opts,
       operation,
       historyRecovery,
       requestedSessionId,
diff --git a/src/main/daemon/post-ready-flush-gate.test.ts b/src/main/daemon/post-ready-flush-gate.test.ts
index f8e58ba7c7d..06ff64db99f 100644
--- a/src/main/daemon/post-ready-flush-gate.test.ts
+++ b/src/main/daemon/post-ready-flush-gate.test.ts
@@ -20,6 +20,14 @@ describe('PostReadyFlushGate', () => {
     vi.useRealTimers()
   })
 
+  it('flushes synchronously when the marker comes from the line editor', () => {
+    gate = new PostReadyFlushGate(onFlush, true)
+    gate.arm()
+    expect(onFlush).toHaveBeenCalledTimes(1)
+    expect(gate.isPending).toBe(false)
+    expect(vi.getTimerCount()).toBe(0)
+  })
+
   it('does not flush immediately when armed', () => {
     gate.arm()
     expect(onFlush).not.toHaveBeenCalled()
diff --git a/src/main/daemon/post-ready-flush-gate.ts b/src/main/daemon/post-ready-flush-gate.ts
index 199bb601024..f7f7a2f1869 100644
--- a/src/main/daemon/post-ready-flush-gate.ts
+++ b/src/main/daemon/post-ready-flush-gate.ts
@@ -1,23 +1,5 @@
-/**
- * Defers a flush callback until after the shell has drawn its prompt and
- * switched the PTY into raw mode.
- *
- * Why: the OSC 777 shell-ready marker fires from zsh's precmd_functions /
- * bash's PROMPT_COMMAND — before the shell draws its prompt and before
- * zle/readline flips the PTY into raw mode. Flushing queued input then lets
- * the kernel (ECHO still on) echo the command once, and the line editor
- * redraws it under the prompt — producing a visible duplicate (e.g. "claude"
- * appears twice on agent launch).
- *
- * Strategy: after arm() is called, wait for prompt bytes plus a short delay
- * for the tcsetattr() that enables raw mode. If the marker-completing scan
- * already saw post-marker bytes, use that same short path immediately.
- * A conservative wall-clock fallback covers ambiguous marker-only cases.
- *
- * Mirrors the gate in local-pty-shell-ready.ts::writeStartupCommandWhenShellReady,
- * which solves the same race on the non-daemon path.
- */
-
+// Bash's prompt and zsh's line-init marker are ready for input immediately.
+// Other shells retain the existing settling delay.
 export const POST_READY_FLUSH_DELAY_MS = 30
 export const POST_READY_FLUSH_FALLBACK_MS = 200
 
@@ -26,7 +8,10 @@ export class PostReadyFlushGate {
   private postDataTimer: ReturnType<typeof setTimeout> | null = null
   private fallbackTimer: ReturnType<typeof setTimeout> | null = null
 
-  constructor(private readonly onFlush: () => void) {}
+  constructor(
+    private readonly onFlush: () => void,
+    private readonly markerIsLineEditorReady = false
+  ) {}
 
   /** True between arm() and the actual flush firing. Callers should treat
    *  input as still-queued during this window to preserve ordering. */
@@ -38,6 +23,10 @@ export class PostReadyFlushGate {
    *  wall-clock fallback unless the marker scan already observed post-marker
    *  bytes, in which case the short post-data settle path is enough. */
   arm(postMarkerBytesObserved = false): void {
+    if (this.markerIsLineEditorReady) {
+      this.onFlush()
+      return
+    }
     this.awaitingPromptDraw = true
     if (postMarkerBytesObserved) {
       this.notifyData()
diff --git a/src/main/daemon/pty-subprocess-managed-agent-env.test.ts b/src/main/daemon/pty-subprocess-managed-agent-env.test.ts
index 5267778088c..d5dbc33246c 100644
--- a/src/main/daemon/pty-subprocess-managed-agent-env.test.ts
+++ b/src/main/daemon/pty-subprocess-managed-agent-env.test.ts
@@ -261,7 +261,7 @@ describe('createPtySubprocess', () => {
     expect(lastCall[2].env.ORCA_SHELL_FEATURES).not.toContain('ready')
   })
 
-  it('keeps plain Codex startup commands on the no-marker wrapper', async () => {
+  it('enables readiness and shell identity for plain Codex startup', async () => {
     const proc = mockPtyProcess()
     spawnMock.mockReturnValue(proc)
     const platform = Object.getOwnPropertyDescriptor(process, 'platform')
@@ -285,7 +285,8 @@ describe('createPtySubprocess', () => {
     const lastCall = spawnMock.mock.calls.at(-1)!
     expect(lastCall[1]).toEqual(['-l'])
     expect(lastCall[2].env.ZDOTDIR).toMatch(ZSH_SHELL_READY_DIR)
-    expect(lastCall[2].env.ORCA_SHELL_FEATURES).not.toContain('ready')
+    expect(lastCall[2].env.ORCA_SHELL_FEATURES).toContain('ready')
+    expect(lastCall[2].env.ORCA_SHELL_FEATURES).toContain('identity')
   })
 
   it('uses shell-ready wrapper for delivery-hinted Codex startup commands', async () => {
diff --git a/src/main/daemon/pty-subprocess/shell-launch-plan.ts b/src/main/daemon/pty-subprocess/shell-launch-plan.ts
index ed8cd5e6a22..12e049d9f72 100644
--- a/src/main/daemon/pty-subprocess/shell-launch-plan.ts
+++ b/src/main/daemon/pty-subprocess/shell-launch-plan.ts
@@ -1,3 +1,4 @@
+import { shouldUseShellReadyStartupDelivery } from '../../../shared/codex-startup-delivery'
 import { win32 as pathWin32 } from 'node:path'
 import { isWindowsGitBashShellPath, resolveWindowsGitBashShellPath } from '../../git-bash'
 import { isPwshAvailable } from '../../pwsh'
@@ -32,10 +33,13 @@ import {
   recognizeAgentProcessFromCommandLine,
   type RecognizedAgentProcess
 } from '../../../shared/agent-process-recognition'
-import { shouldUseShellReadyStartupDelivery } from '../../../shared/codex-startup-delivery'
 import { ORCA_HERMES_STARTUP_QUERY_ENV } from '../../../shared/hermes-startup-query'
 import { WINDOWS_GIT_BASH_SHELL } from '../../../shared/windows-terminal-shell'
-import { getShellLaunchConfig, resolvePtyShellPath } from '../shell-ready'
+import {
+  getShellLaunchConfig,
+  resolvePtyShellPath,
+  shellReadyMarkerComesFromLineEditor
+} from '../shell-ready'
 import { resolveWslSessionContext } from '../wsl-session-context'
 import { finalizeDaemonPtyEnvironment, rescrubDaemonPtyEnvironment } from './spawn-environment'
 import type { PtySubprocessOptions } from '../pty-subprocess'
@@ -60,7 +64,6 @@ export function createPtyShellLaunchPlan(
   let startupCommandDeliveredInShellArgs = false
   let windowsFallbackAttempts: WindowsShellSpawnAttempt[] = []
   const startupAgentRecognition = recognizeAgentProcessFromCommandLine(opts.command)
-  const isCodexStartupCommand = startupAgentRecognition?.agent === 'codex'
   const requestedCwd = opts.cwd || resolveSafePtyDefaultCwd()
   if (opts.command && startupAgentRecognition) {
     assertSafeAgentStartupCwd(requestedCwd, opts.command)
@@ -192,9 +195,10 @@ export function createPtyShellLaunchPlan(
     }
     const waitsForShellReady =
       Boolean(opts.command) &&
-      (!isCodexStartupCommand ||
+      (startupAgentRecognition?.agent !== 'codex' ||
+        shellReadyMarkerComesFromLineEditor(shellPath) ||
         shouldUseShellReadyStartupDelivery({
-          command: opts.command as string,
+          command: opts.command,
           startupCommandDelivery: opts.startupCommandDelivery
         }))
     delete env.ORCA_SHELL_FEATURES
diff --git a/src/main/daemon/session-shell-ready-barrier.ts b/src/main/daemon/session-shell-ready-barrier.ts
index e7562e23224..538fd57a49a 100644
--- a/src/main/daemon/session-shell-ready-barrier.ts
+++ b/src/main/daemon/session-shell-ready-barrier.ts
@@ -1,3 +1,4 @@
+import { shellReadyMarkerComesFromLineEditor } from './shell-ready'
 import {
   installDeviceAttributesResponder,
   STARTUP_DA1_RESPONSE
@@ -19,7 +20,6 @@ import { basename } from 'node:path'
 import type { ShellReadyState } from './types'
 
 const SHELL_READY_TIMEOUT_MS = 15_000
-// Why: Codex skips marker-gated command delivery; this only bounds older daemon/local paths that still report shell-ready for Codex.
 export const CODEX_SHELL_READY_TIMEOUT_MS = 300
 
 export type SessionShellReadyBarrierDeps = {
@@ -69,7 +69,10 @@ export class SessionShellReadyBarrier {
       this._state = 'unsupported'
     }
 
-    this.postReadyFlushGate = new PostReadyFlushGate(() => this.flushPreReadyQueue())
+    this.postReadyFlushGate = new PostReadyFlushGate(
+      () => this.flushPreReadyQueue(),
+      shellReadyMarkerComesFromLineEditor(deps.subprocess.shellPath ?? '')
+    )
   }
 
   get state(): ShellReadyState {
diff --git a/src/main/daemon/shell-ready.ts b/src/main/daemon/shell-ready.ts
index 9dc60b7c980..d51f6efb80a 100644
--- a/src/main/daemon/shell-ready.ts
+++ b/src/main/daemon/shell-ready.ts
@@ -101,6 +101,11 @@ export function resolvePtyShellPath(env: Record<string, string>): string {
   return env.SHELL || process.env.SHELL || '/bin/zsh'
 }
 
+export function shellReadyMarkerComesFromLineEditor(shellPath: string): boolean {
+  const shellName = pathWin32.basename(basename(shellPath)).toLowerCase()
+  return shellName === 'bash' || shellName === 'zsh'
+}
+
 export function shellPathSupportsPtyStartupBarrier(shellPath: string): boolean {
   const shellName = pathWin32.basename(basename(shellPath)).toLowerCase()
   // Why fish: markerless, its startup command is written before fish's reader owns
diff --git a/src/main/git/command-runner/spawned-command-tree-kill.ts b/src/main/git/command-runner/spawned-command-tree-kill.ts
index c2fefcba1bc..324e04f1db3 100644
--- a/src/main/git/command-runner/spawned-command-tree-kill.ts
+++ b/src/main/git/command-runner/spawned-command-tree-kill.ts
@@ -1,4 +1,5 @@
 import { spawn, type ChildProcess } from 'node:child_process'
+import { admitSelfInitiatedTreeKill } from '../../own-chromium-tree-kill-guard'
 
 const WINDOWS_TREE_KILL_WAIT_MS = 2_000
 
@@ -8,6 +9,14 @@ export function killSpawnedCommandTree(child: ChildProcess): Promise<void> {
     child.kill()
     return Promise.resolve()
   }
+  if (
+    !admitSelfInitiatedTreeKill({ pid, site: 'git-command-tree-kill', scope: 'win-taskkill-tree' })
+  ) {
+    // Refusal blocks the pid-addressed tree walk, never the termination: the
+    // handle-addressed root kill cannot reach a recycled pid.
+    child.kill()
+    return Promise.resolve()
+  }
   return new Promise((resolve) => {
     let killer: ChildProcess
     try {
diff --git a/src/main/ipc/notebook.ts b/src/main/ipc/notebook.ts
index 9255ab7383d..d90ab3616de 100644
--- a/src/main/ipc/notebook.ts
+++ b/src/main/ipc/notebook.ts
@@ -4,6 +4,7 @@ import { dirname } from 'node:path'
 import { ipcMain } from 'electron'
 import type { Store } from '../persistence'
 import { resolveAuthorizedPath } from './filesystem-auth'
+import { admitSelfInitiatedTreeKill } from '../own-chromium-tree-kill-guard'
 
 export type NotebookRunResult = {
   stdout: string
@@ -53,7 +54,8 @@ function appendBounded(capture: BoundedCapture, chunk: Buffer): void {
   capture.truncated = true
 }
 
-function terminateNotebookProcessTree(
+/** Exported for the refusal-fallback test; the timeout path is otherwise unreachable. */
+export function terminateNotebookProcessTree(
   child: ChildProcessWithoutNullStreams
 ): ReturnType<typeof setTimeout> | null {
   if (!child.pid) {
@@ -62,6 +64,18 @@ function terminateNotebookProcessTree(
   }
 
   if (process.platform === 'win32') {
+    if (
+      !admitSelfInitiatedTreeKill({
+        pid: child.pid,
+        site: 'notebook-cell-timeout',
+        scope: 'win-taskkill-tree'
+      })
+    ) {
+      // Refusal blocks the tree walk, not the termination: killing the root by
+      // handle cannot reach a recycled pid, and a timed-out cell must still stop.
+      child.kill()
+      return null
+    }
     try {
       // Why: a timed-out cell can spawn descendants. taskkill /T is the
       // Windows equivalent of terminating the whole process group.
diff --git a/src/main/main-process-tree-kill-gate.test.ts b/src/main/main-process-tree-kill-gate.test.ts
new file mode 100644
index 00000000000..40b1421c32f
--- /dev/null
+++ b/src/main/main-process-tree-kill-gate.test.ts
@@ -0,0 +1,184 @@
+import { readFileSync, readdirSync, statSync } from 'node:fs'
+import { join, relative, resolve } from 'node:path'
+import { describe, expect, it } from 'vitest'
+
+/**
+ * The ratchet behind the guard's claim to be a choke point.
+ *
+ * `admitSelfInitiatedTreeKill` is only "one decision" for as long as every
+ * pid-addressed `taskkill /pid <pid> /t /f` in Electron main asks it. Each such
+ * kill can land on a recycled pid that is now one of Orca's own Chromium
+ * processes (#10680), and an ungated one is also invisible to
+ * `selfInitiatedTreeKillCount`, which makes a zero read as exculpatory when it
+ * is not. A new family fails here rather than in the field.
+ *
+ * Exactly what is enforced, so no comment elsewhere claims more: per file, the
+ * number of gate admissions must be at least the number of `/pid` call sites.
+ * Counting sites rather than files is the point — a file-granular scan would let
+ * a second, ungated taskkill land inside a family that already mentions the gate,
+ * which is the shape the six highest-risk files now have. What it still cannot
+ * see: a site that pairs an ungated kill with a second admission of an already
+ * gated one in the same file, and a kill whose `/pid` argument is itself built
+ * from a variable.
+ */
+const REPOSITORY_ROOT = resolve(__dirname, '..', '..')
+const MAIN_DIRECTORY = 'src/main/'
+const SCANNED_EXTENSIONS = ['.ts', '.tsx']
+const IGNORED_DIRECTORIES = new Set([
+  'node_modules',
+  'dist',
+  'out',
+  'build',
+  '.git',
+  '__fixtures__'
+])
+
+/**
+ * One match per call site. Keyed on the `/pid` argument rather than the program
+ * name because `/pid <n>` is what makes the kill pid-addressed — it walks
+ * whatever tree owns that pid *now* — and because the literal survives a
+ * `taskkill` spawned through a constant or a variable, which a quoted-program
+ * pattern misses entirely.
+ */
+const PID_ADDRESSED_KILL_SITE = /['"]\/pid['"]/gi
+
+/**
+ * A call, not an import or a comment: `admitSelfInitiatedTreeKill` in main, and
+ * `admitProcessTreeKill` for the `src/shared` seam main installs the same gate
+ * into, which shared code cannot import directly.
+ */
+const GATE_ADMISSION = /\badmit(?:SelfInitiatedTreeKill|ProcessTreeKill)\s*\(/g
+
+function countMatches(source: string, pattern: RegExp): number {
+  return source.match(pattern)?.length ?? 0
+}
+
+/** Sites left over once each admission in the file has claimed one. */
+function ungatedKillSiteCount(source: string): number {
+  return Math.max(
+    countMatches(source, PID_ADDRESSED_KILL_SITE) - countMatches(source, GATE_ADMISSION),
+    0
+  )
+}
+
+/**
+ * Only ever shrinks. Each entry states why the gate cannot reach it — never
+ * "not got to yet", which is what a new ungated family would also look like.
+ */
+const UNGATED_TASKKILL_ALLOWLIST = new Map<string, string>([
+  [
+    'src/main/browser/browser-route-egress-electron-launch.ts',
+    'Electron probe reached only from *.electron.test.ts; kills the probe Electron it spawned'
+  ],
+  [
+    'src/main/browser/browser-route-persisted-worker-electron-process.ts',
+    'Electron probe reached only from *.electron.test.ts; kills the probe Electron it spawned'
+  ],
+  [
+    'src/cli/handlers/interactive-login-interruption.ts',
+    'CLI host: no Chromium pid on the machine to reach, and no reader for the ring'
+  ],
+  [
+    'src/relay/subprocess-tree-termination.ts',
+    'Relay host: same, and the relay cannot import the main-process gate'
+  ]
+])
+
+function isTestFile(path: string): boolean {
+  return /\.(?:test|spec)\.tsx?$/.test(path) || /(?:test-harness|test-fixture|fixture)/.test(path)
+}
+
+function scanSourceFiles(directory: string, found: string[] = []): string[] {
+  for (const entry of readdirSync(directory)) {
+    if (IGNORED_DIRECTORIES.has(entry)) {
+      continue
+    }
+    const path = join(directory, entry)
+    if (statSync(path).isDirectory()) {
+      scanSourceFiles(path, found)
+      continue
+    }
+    if (SCANNED_EXTENSIONS.some((extension) => entry.endsWith(extension)) && !isTestFile(path)) {
+      found.push(path)
+    }
+  }
+  return found
+}
+
+// Only the Node-side hosts: a renderer or preload cannot spawn a process at all.
+const SCANNED_HOSTS = ['src/main', 'src/shared', 'src/cli', 'src/relay']
+
+/** Scanned once at import: 10k files is seconds, and every case below reuses it. */
+const PID_ADDRESSED_KILL_FILES = SCANNED_HOSTS.flatMap((host) =>
+  scanSourceFiles(join(REPOSITORY_ROOT, host))
+    .map((path) => ({
+      path: relative(REPOSITORY_ROOT, path).split('\\').join('/'),
+      source: readFileSync(path, 'utf8')
+    }))
+    .filter((file) => countMatches(file.source, PID_ADDRESSED_KILL_SITE) > 0)
+)
+
+function pidAddressedKillFiles(): { path: string; source: string }[] {
+  return PID_ADDRESSED_KILL_FILES
+}
+
+describe('main-process tree-kill gate', () => {
+  it('finds the taskkill families it is meant to police', () => {
+    // Falsifiable: a scanner that matched nothing would pass every case below.
+    expect(pidAddressedKillFiles().map((file) => file.path)).toContain(
+      'src/main/windows-process-tree-kill.ts'
+    )
+  })
+
+  it('routes every pid-addressed taskkill in Electron main through the gate', () => {
+    const ungated = pidAddressedKillFiles()
+      .filter((file) => file.path.startsWith(MAIN_DIRECTORY))
+      .filter((file) => ungatedKillSiteCount(file.source) > 0)
+      .map((file) => file.path)
+      .filter((path) => !UNGATED_TASKKILL_ALLOWLIST.has(path))
+
+    expect(ungated).toEqual([])
+  })
+
+  it('leaves no pid-addressed taskkill outside main unaccounted for', () => {
+    const unaccounted = pidAddressedKillFiles()
+      .filter((file) => !file.path.startsWith(MAIN_DIRECTORY))
+      .filter((file) => ungatedKillSiteCount(file.source) > 0)
+      .map((file) => file.path)
+      .filter((path) => !UNGATED_TASKKILL_ALLOWLIST.has(path))
+
+    expect(unaccounted).toEqual([])
+  })
+
+  it('counts call sites, not files: a second ungated kill in a gated file is caught', () => {
+    // The failure a file-granular scan let through: one gate mention exempting
+    // every taskkill in the file.
+    const gated = `
+      import { admitSelfInitiatedTreeKill } from './own-chromium-tree-kill-guard'
+      if (admitSelfInitiatedTreeKill({ pid, site: 's', scope: 'win-taskkill-tree' })) {
+        spawn('taskkill', ['/pid', String(pid), '/t', '/f'])
+      }
+    `
+
+    expect(ungatedKillSiteCount(gated)).toBe(0)
+    expect(
+      ungatedKillSiteCount(`${gated}\nspawn('taskkill', ['/pid', String(other), '/t', '/f'])`)
+    ).toBe(1)
+  })
+
+  it('sees a kill whose program name comes from a constant', () => {
+    // A quoted-program pattern misses this shape; the `/pid` argument does not.
+    expect(
+      ungatedKillSiteCount(`
+        const KILLER = 'taskkill'
+        spawn(KILLER, ['/pid', String(pid), '/t', '/f'])
+      `)
+    ).toBe(1)
+  })
+
+  it('keeps the allowlist honest: every entry still spawns a taskkill', () => {
+    const spawning = new Set(pidAddressedKillFiles().map((file) => file.path))
+
+    expect([...UNGATED_TASKKILL_ALLOWLIST.keys()].filter((path) => !spawning.has(path))).toEqual([])
+  })
+})
diff --git a/src/main/orca-chromium-process-pids.ts b/src/main/orca-chromium-process-pids.ts
index b2613e42b79..3282f3a4d66 100644
--- a/src/main/orca-chromium-process-pids.ts
+++ b/src/main/orca-chromium-process-pids.ts
@@ -12,6 +12,12 @@ import { recordCoalescedDurableCrashBreadcrumb } from './crash-reporting/durable
  * Empty on a Node host and empty on failure: that is "no refusal proven", never
  * "safe to kill" — callers must keep every other guard they already have.
  *
+ * The other direction is real too, and bounded by design: `getAppMetrics()` can
+ * still list a renderer Electron has not finished reaping, so on Windows a pid
+ * already recycled onto an unrelated child of ours reads as `own` and its tree
+ * walk is refused. That is why a refusal only blocks the pid-addressed walk and
+ * every gated site still kills its own root through the child handle.
+ *
  * Why failure stays open rather than refusing everything: a refusal is not free.
  * `terminateWindowsProcessTree` resolves without killing, and
  * `killSourceControlAgentProcess` returns that straight to a caller that then
diff --git a/src/main/own-chromium-tree-kill-guard.test.ts b/src/main/own-chromium-tree-kill-guard.test.ts
index bd3b1674e18..7b9c30687bc 100644
--- a/src/main/own-chromium-tree-kill-guard.test.ts
+++ b/src/main/own-chromium-tree-kill-guard.test.ts
@@ -13,7 +13,12 @@ import {
 import { readOrcaChromiumProcessPids } from './orca-chromium-process-pids'
 import { classifyWindowsTreeKillTarget } from './windows-pty-root-identity'
 import { terminateWindowsProcessTree } from './windows-process-tree-kill'
-import { admitSelfInitiatedTreeKill } from './own-chromium-tree-kill-guard'
+import {
+  admitSelfInitiatedTreeKill,
+  installMainProcessTreeKillGate
+} from './own-chromium-tree-kill-guard'
+import { killCodexAppServerProcessTree } from './codex/codex-app-server-session'
+import { setProcessTreeKillGate } from '../shared/child-process/process-tree-kill-gate'
 import { resetSelfInitiatedTreeKillLogForTest } from './crash-reporting/self-initiated-tree-kill-log'
 import {
   clearCrashBreadcrumbsForTest,
@@ -57,6 +62,7 @@ beforeEach(() => {
   setActiveSink({ push: () => {}, flush: () => {}, close: () => {} })
   clearCrashBreadcrumbsForTest()
   resetSelfInitiatedTreeKillLogForTest()
+  installMainProcessTreeKillGate()
 })
 
 afterEach(() => {
@@ -66,6 +72,7 @@ afterEach(() => {
   vi.restoreAllMocks()
   _resetTracerForTests()
   clearCrashBreadcrumbsForTest()
+  setProcessTreeKillGate(null)
 })
 
 describe('refusing to tree-kill our own Chromium processes', () => {
@@ -143,6 +150,38 @@ describe('refusing to tree-kill our own Chromium processes', () => {
     )
   })
 
+  it('refuses the codex app-server deadline kill against one of our own pids', () => {
+    const spawnImpl = vi.fn(() => ({ on: vi.fn(), unref: vi.fn() }))
+    const child = { pid: RENDERER_PID, kill: vi.fn() }
+
+    killCodexAppServerProcessTree(child as never, {
+      platform: 'win32',
+      spawnImpl: spawnImpl as never
+    })
+
+    // The deadline timer fires on `child.pid` alone; a reaped-then-recycled pid
+    // is the stale-pid mechanism this gate exists to stop.
+    expect(spawnImpl).not.toHaveBeenCalled()
+    expect(getCrashBreadcrumbSnapshot()).toEqual([
+      expect.objectContaining({ name: 'self_tree_kill_refused_own_chromium' })
+    ])
+  })
+
+  it('still lets the codex app-server deadline kill reach a foreign pid', () => {
+    const killer = { on: vi.fn(), unref: vi.fn() }
+    const spawnImpl = vi.fn(() => killer)
+
+    killCodexAppServerProcessTree({ pid: 7777, kill: vi.fn() } as never, {
+      platform: 'win32',
+      spawnImpl: spawnImpl as never
+    })
+
+    expect(spawnImpl).toHaveBeenCalledWith('taskkill', ['/pid', '7777', '/t', '/f'], {
+      stdio: 'ignore',
+      windowsHide: true
+    })
+  })
+
   /**
    * Fail-open is the deliberate choice — see `orca-chromium-process-pids.ts` for
    * why refusing everything is worse — so the crumb is the only thing that keeps
diff --git a/src/main/own-chromium-tree-kill-guard.ts b/src/main/own-chromium-tree-kill-guard.ts
index 4daedf4faa4..24b6a4b7327 100644
--- a/src/main/own-chromium-tree-kill-guard.ts
+++ b/src/main/own-chromium-tree-kill-guard.ts
@@ -4,16 +4,23 @@ import {
   type SelfInitiatedTreeKillScope
 } from './crash-reporting/self-initiated-tree-kill-log'
 import { readOrcaChromiumProcessPids } from './orca-chromium-process-pids'
+import { setProcessTreeKillGate } from '../shared/child-process/process-tree-kill-gate'
 
 /**
- * Gate every main-process tree-kill through one decision: refuse the pid when
- * Electron is currently accounting for it, otherwise put it on the record.
+ * Gate every main-process tree-kill through one decision: refuse a pid-addressed
+ * walk when Electron is currently accounting for the pid, otherwise put the
+ * kill on the record.
  *
  * Why a shared gate rather than a check inside `terminateWindowsProcessTree`:
- * the codex and claude account-login teardowns run their own `taskkill /T /F`
- * with different lifetimes (one sync, one with its own timeout ladder), so a
- * guard that only lived in the tree-kill helper would cover one of three
- * families. Returns false when the caller must not kill.
+ * five other families in main run their own `taskkill /T /F` with different
+ * lifetimes (sync, fire-and-forget, timeout ladder), and three more live in
+ * `src/shared` and reach this through `process-tree-kill-gate`, so a guard that
+ * only lived in the tree-kill helper would cover one of nine.
+ * `main-process-tree-kill-gate.test.ts` holds that set closed by counting `/pid`
+ * call sites against gate admissions per file, not by file. Returns false
+ * when the caller must not walk that pid's tree; the caller still kills its own
+ * root through the child handle (`refused-tree-kill-root-termination.test.ts`),
+ * so a refusal is never a process leak.
  *
  * Electron main only, by construction. `terminateWindowsProcessTree` also runs
  * in the standalone daemon (the `pty-descendant-sweep` site), where
@@ -30,11 +37,26 @@ export function admitSelfInitiatedTreeKill(target: {
 }): boolean {
   // Why: no PTY root, codex root or git child is ever one of our own Chromium
   // processes, so a pid that is means the caller is about to kill a renderer,
-  // the GPU or the browser itself (#10680).
-  if (readOrcaChromiumProcessPids().has(target.pid)) {
-    recordRefusedOwnChromiumTreeKill(target)
-    return false
+  // the GPU or the browser itself (#10680). Only the pid-addressed scope can
+  // land there: a POSIX group holds only what Orca put in it, so that arm is
+  // recorded and admitted like every other group kill in main, and a stale
+  // `getAppMetrics()` entry cannot orphan a macOS/Linux tree.
+  const isOwnChromiumPid =
+    target.scope === 'win-taskkill-tree' && readOrcaChromiumProcessPids().has(target.pid)
+  try {
+    if (isOwnChromiumPid) {
+      recordRefusedOwnChromiumTreeKill(target)
+    } else {
+      recordSelfInitiatedTreeKill(target)
+    }
+  } catch {
+    // Recording must never turn a successful termination into a failed one, and
+    // never flip the decision: it is taken above, before anything can throw.
   }
-  recordSelfInitiatedTreeKill(target)
-  return true
+  return !isOwnChromiumPid
+}
+
+/** Hands the gate to the shared choke points, which cannot import main. */
+export function installMainProcessTreeKillGate(): void {
+  setProcessTreeKillGate((kill) => admitSelfInitiatedTreeKill(kill))
 }
diff --git a/src/main/refused-tree-kill-root-termination.test.ts b/src/main/refused-tree-kill-root-termination.test.ts
new file mode 100644
index 00000000000..ada4b5942a9
--- /dev/null
+++ b/src/main/refused-tree-kill-root-termination.test.ts
@@ -0,0 +1,220 @@
+import { afterEach, beforeEach, describe, expect, it, vi } from 'vitest'
+
+const { spawnMock, execFileMock, queryWindowsProcessDescendantsMock } = vi.hoisted(() => ({
+  spawnMock: vi.fn(),
+  execFileMock: vi.fn(),
+  queryWindowsProcessDescendantsMock: vi.fn()
+}))
+
+vi.mock('node:child_process', async (importOriginal) => ({
+  ...(await importOriginal<Record<string, unknown>>()),
+  spawn: spawnMock,
+  execFile: execFileMock
+}))
+vi.mock('electron', () => ({ ipcMain: { handle: vi.fn(), on: vi.fn() } }))
+vi.mock('./providers/windows-foreground-process-rows', () => ({
+  queryWindowsProcessDescendants: queryWindowsProcessDescendantsMock
+}))
+
+import {
+  getAppEnvironment,
+  hasAppEnvironment,
+  setAppEnvironment,
+  type AppEnvironment
+} from '../shared/app-environment'
+import { installMainProcessTreeKillGate } from './own-chromium-tree-kill-guard'
+import { setProcessTreeKillGate } from '../shared/child-process/process-tree-kill-gate'
+import { resetSelfInitiatedTreeKillLogForTest } from './crash-reporting/self-initiated-tree-kill-log'
+import {
+  clearCrashBreadcrumbsForTest,
+  getCrashBreadcrumbSnapshot
+} from './crash-reporting/crash-breadcrumb-store'
+import { _resetTracerForTests, setActiveSink } from './observability/tracer'
+import { terminateNotebookProcessTree } from './ipc/notebook'
+import { killLocalPrecheckProcessTree } from './automations/precheck-runner'
+import { killRecipeProcess } from '../shared/ephemeral-vm-recipe-process'
+import { killSpawnedCommandTree } from './git/command-runner/spawned-command-tree-kill'
+import { killCodexAppServerProcessTree } from './codex/codex-app-server-session'
+import { signalProcessTree } from '../shared/child-process/process-tree-termination'
+import { killSourceControlAgentProcess } from './text-generation/source-control-local-process'
+import { terminateCodexTurnProcesses } from './codex/codex-structured-turn-processes'
+
+/** A pid Electron reports as one of ours: every gate below must refuse it. */
+const RENDERER_PID = 1001
+
+function appEnvironment(): AppEnvironment {
+  return {
+    getPath: () => process.cwd(),
+    getAppPath: () => process.cwd(),
+    getVersion: () => '0.0.0-test',
+    isPackaged: () => false,
+    onWillQuit: () => {},
+    exit: () => {},
+    getAppMetrics: (() => [
+      { pid: RENDERER_PID, type: 'Tab' }
+    ]) as unknown as AppEnvironment['getAppMetrics']
+  }
+}
+
+let previousEnvironment: AppEnvironment | null = null
+let previousPlatform: PropertyDescriptor | undefined
+
+function setPlatform(platform: NodeJS.Platform): void {
+  Object.defineProperty(process, 'platform', { value: platform, configurable: true })
+}
+
+beforeEach(() => {
+  previousEnvironment = hasAppEnvironment() ? getAppEnvironment() : null
+  previousPlatform = Object.getOwnPropertyDescriptor(process, 'platform')
+  setAppEnvironment(appEnvironment())
+  setActiveSink(null)
+  clearCrashBreadcrumbsForTest()
+  resetSelfInitiatedTreeKillLogForTest()
+  installMainProcessTreeKillGate()
+  spawnMock.mockReset()
+  execFileMock.mockReset()
+  queryWindowsProcessDescendantsMock.mockReset()
+  spawnMock.mockReturnValue({ on: vi.fn(), once: vi.fn(), unref: vi.fn(), kill: vi.fn() })
+})
+
+afterEach(() => {
+  setProcessTreeKillGate(null)
+  if (previousPlatform) {
+    Object.defineProperty(process, 'platform', previousPlatform)
+  }
+  if (previousEnvironment) {
+    setAppEnvironment(previousEnvironment)
+  }
+  _resetTracerForTests()
+})
+
+/**
+ * A refusal must never become a process leak. The gate only blocks the
+ * pid-addressed tree walk; the root kill is addressed by the child handle, so it
+ * cannot reach the recycled pid we refused, and skipping it would report a
+ * timed-out command as stopped while its tree keeps running.
+ */
+describe('a refused tree-kill still terminates the root it owns', () => {
+  it('kills the git command root when the tree walk is refused', async () => {
+    setPlatform('win32')
+    const child = { pid: RENDERER_PID, kill: vi.fn() }
+
+    await killSpawnedCommandTree(child as never)
+
+    expect(spawnMock).not.toHaveBeenCalled()
+    expect(child.kill).toHaveBeenCalledTimes(1)
+  })
+
+  it('kills the notebook cell root when the tree walk is refused', () => {
+    setPlatform('win32')
+    const child = { pid: RENDERER_PID, kill: vi.fn() }
+
+    expect(terminateNotebookProcessTree(child as never)).toBeNull()
+
+    expect(spawnMock).not.toHaveBeenCalled()
+    expect(child.kill).toHaveBeenCalledTimes(1)
+  })
+
+  it('kills the automation precheck root when the tree walk is refused', () => {
+    setPlatform('win32')
+    const child = { pid: RENDERER_PID, kill: vi.fn() }
+
+    expect(killLocalPrecheckProcessTree(child as never)).toBeNull()
+
+    expect(spawnMock).not.toHaveBeenCalled()
+    expect(child.kill).toHaveBeenCalledTimes(1)
+  })
+
+  it('kills the ephemeral-VM recipe root when the tree walk is refused', () => {
+    setPlatform('win32')
+    const child = { pid: RENDERER_PID, kill: vi.fn() }
+
+    killRecipeProcess(child as never, true)
+
+    expect(spawnMock).not.toHaveBeenCalled()
+    expect(child.kill).toHaveBeenCalledWith('SIGKILL')
+  })
+
+  it('kills the codex app-server root when the deadline tree walk is refused', () => {
+    const child = { pid: RENDERER_PID, kill: vi.fn() }
+
+    killCodexAppServerProcessTree(child as never, {
+      platform: 'win32',
+      spawnImpl: spawnMock as never
+    })
+
+    expect(spawnMock).not.toHaveBeenCalled()
+    expect(child.kill).toHaveBeenCalledWith('SIGKILL')
+  })
+
+  it('kills the commit-message agent root when the tree walk is refused', async () => {
+    setPlatform('win32')
+    const child = { pid: RENDERER_PID, kill: vi.fn() }
+
+    await killSourceControlAgentProcess(child as never)
+
+    expect(execFileMock).not.toHaveBeenCalled()
+    expect(child.kill).toHaveBeenCalledWith('SIGKILL')
+  })
+
+  it('kills the runProcess root when the Windows arm of the shared choke point is refused', async () => {
+    setPlatform('win32')
+    const windowsChild = { pid: RENDERER_PID, kill: vi.fn(), exitCode: null, signalCode: null }
+
+    await expect(signalProcessTree(windowsChild as never, 'SIGKILL')).resolves.toBe(false)
+    expect(spawnMock).not.toHaveBeenCalled()
+    expect(windowsChild.kill).toHaveBeenCalledWith('SIGKILL')
+  })
+
+  it('still signals the POSIX process group: a group only holds what Orca put in it', async () => {
+    // Same contract as main and as the other three POSIX group arms in main
+    // (claude-login, codex teardown, PTY sweep): record, never refuse. A stale
+    // `getAppMetrics()` entry must not orphan a macOS/Linux tree.
+    setPlatform('linux')
+    const posixChild = { pid: RENDERER_PID, kill: vi.fn(), exitCode: null, signalCode: null }
+    const processKill = vi.spyOn(process, 'kill').mockImplementation(() => true)
+
+    await expect(signalProcessTree(posixChild as never, 'SIGKILL')).resolves.toBe(true)
+    expect(processKill).toHaveBeenCalledWith(-RENDERER_PID, 'SIGKILL')
+    expect(posixChild.kill).not.toHaveBeenCalled()
+    expect(getCrashBreadcrumbSnapshot()).toEqual([
+      expect.objectContaining({
+        name: 'self_tree_kill',
+        data: expect.objectContaining({ pid: RENDERER_PID, scope: 'posix-process-group' })
+      })
+    ])
+    processKill.mockRestore()
+  })
+})
+
+/**
+ * The one gated site with nothing to fall back to: the roots it kills are found
+ * by a process-table walk, not spawned here, so there is no child handle. A
+ * refusal must then be visible — the refusal crumb is written and the turn is
+ * reported as not cancelled — rather than resolving as if the tree had gone.
+ */
+describe('a refused tree-kill with no handle to fall back to', () => {
+  it('reports the codex turn as not cancelled and records the refused added root', async () => {
+    const appServerPid = 500
+    const addedRoot = {
+      pid: RENDERER_PID,
+      ppid: appServerPid,
+      name: 'node.exe',
+      command: 'node',
+      depth: 1
+    }
+    queryWindowsProcessDescendantsMock.mockResolvedValue([addedRoot])
+
+    await expect(
+      terminateCodexTurnProcesses(appServerPid, { platform: 'win32', identities: new Map() })
+    ).resolves.toBe(false)
+
+    expect(execFileMock).not.toHaveBeenCalled()
+    expect(getCrashBreadcrumbSnapshot()).toEqual([
+      expect.objectContaining({
+        name: 'self_tree_kill_refused_own_chromium',
+        data: expect.objectContaining({ pid: RENDERER_PID, site: 'codex-turn-added-roots' })
+      })
+    ])
+  })
+})
diff --git a/src/main/runtime/orca-runtime-resolve-recovered-structured-tui-transcript.ts b/src/main/runtime/orca-runtime-resolve-recovered-structured-tui-transcript.ts
index cfb8b421966..aef04bde6bc 100644
--- a/src/main/runtime/orca-runtime-resolve-recovered-structured-tui-transcript.ts
+++ b/src/main/runtime/orca-runtime-resolve-recovered-structured-tui-transcript.ts
@@ -3,6 +3,8 @@ import { OrcaRuntimeWithStopStructuredSessionProcess } from './orca-runtime-stop
 import type { AgentSessionOwnerBinding } from '../../shared/agent-session-host-authority'
 import { agentSessionOwnerBindingsEqual } from '../../shared/claimed-agent-pty-owner-snapshot'
 import { resolvePinnedCodexRolloutProof } from '../codex/codex-tui-rollout-proof'
+import { supportsCodexStructuredLocation } from '../codex/codex-structured-location-support'
+import { supportsClaudeStructuredLocation } from '../claude/claude-structured-location-support'
 import { getStructuredAgentSessionHost } from '../native-chat/agent-session-wire/structured-agent-session-registry'
 import { resolveStructuredAgentSessionCreateSupport } from '../native-chat/structured-agent-session-create-support'
 import { LOCAL_EXECUTION_HOST_ID } from '../../shared/execution-host'
@@ -51,13 +53,13 @@ export class OrcaRuntimeWithResolveRecoveredStructuredTuiTranscript extends Orca
     agent: 'claude' | 'codex'
   ): Promise<{ supported: boolean; reason?: 'agent' | 'remote' | 'wsl' }> {
     const location = await this.resolveStructuredAgentSessionLocation(worktreeSelector)
-    await this.ensureStructuredAgentSessionHost()
-    // The verdict lives in a typechecked module; this file is @ts-nocheck.
     return resolveStructuredAgentSessionCreateSupport({
       agent,
       location,
       adapterSupportsCreate:
-        getStructuredAgentSessionHost()?.supportsCreate(location, agent) === true,
+        agent === 'claude'
+          ? supportsClaudeStructuredLocation(location)
+          : supportsCodexStructuredLocation(location),
       getSettings: () => this.requireStore().getSettings()
     })
   }
diff --git a/src/main/runtime/structured-agent-session-support-probe.test.ts b/src/main/runtime/structured-agent-session-support-probe.test.ts
new file mode 100644
index 00000000000..e393e41f3a4
--- /dev/null
+++ b/src/main/runtime/structured-agent-session-support-probe.test.ts
@@ -0,0 +1,174 @@
+import { afterEach, describe, expect, it, vi } from 'vitest'
+import { OrcaRuntimeService } from './orca-runtime'
+import {
+  getStructuredAgentSessionHost,
+  setStructuredAgentSessionHost
+} from '../native-chat/agent-session-wire/structured-agent-session-registry'
+import { agentSessionPtyWriteGate } from './agent-session-pty-write-gate'
+
+type InstallEffects = {
+  storeOpened: boolean
+  writeGateAttached: boolean
+  reaperStarted: boolean
+}
+
+/** Stands in for `install()` by performing the three effects it performs, so a probe that
+ *  reinstalls the host is caught by what the install *does*, not by a call count alone. */
+function stubStructuredHostInstall(runtime: OrcaRuntimeService): {
+  effects: InstallEffects
+  ensure: ReturnType<typeof vi.fn>
+} {
+  const effects: InstallEffects = {
+    storeOpened: false,
+    writeGateAttached: false,
+    reaperStarted: false
+  }
+  // `supportsCreate` answers as the real Codex adapter would, so a probe that reinstalls the host
+  // still returns the right answer and fails on the install effects alone.
+  const host = {
+    reconcileRestartLeases: vi.fn(async () => {}),
+    supportsCreate: (location: { executionHostId: string; wslDistro: string | null }) =>
+      location.executionHostId === 'local' && location.wslDistro === null
+  }
+  const ensure = vi.fn(async () => {
+    effects.storeOpened = true
+    effects.reaperStarted = true
+    agentSessionPtyWriteGate.attachRecordLookup(() => null)
+    effects.writeGateAttached = true
+    setStructuredAgentSessionHost(host as never)
+  })
+  vi.spyOn(runtime, 'ensureStructuredAgentSessionHost').mockImplementation(ensure)
+  return { effects, ensure }
+}
+
+type TestLocation = {
+  executionHostId: string
+  wslDistro: string | null
+  workspaceKind?: 'folder' | 'git-worktree'
+}
+
+type SupportResult = {
+  supported: boolean
+  reason?: 'agent' | 'remote' | 'wsl'
+}
+
+function createRuntime(location: TestLocation): OrcaRuntimeService {
+  const runtime = new OrcaRuntimeService({ getSettings: () => ({}) } as never)
+  const internal = runtime as unknown as {
+    resolveStructuredAgentSessionLocation: () => Promise<unknown>
+  }
+  internal.resolveStructuredAgentSessionLocation = vi.fn(async () => ({
+    executionHostId: location.executionHostId,
+    wslDistro: location.wslDistro,
+    workspaceId: 'workspace-1',
+    workspaceKind: location.workspaceKind ?? 'git-worktree'
+  }))
+  return runtime
+}
+
+async function expectSupportWithoutInstall(input: {
+  agent: 'claude' | 'codex'
+  location: TestLocation
+  expected: SupportResult
+  repetitions?: number
+}): Promise<void> {
+  const runtime = createRuntime(input.location)
+  const { effects, ensure } = stubStructuredHostInstall(runtime)
+
+  const answers: SupportResult[] = []
+  for (let index = 0; index < (input.repetitions ?? 1); index += 1) {
+    answers.push(
+      await runtime.getStructuredAgentSessionCreateSupport('id:workspace-1', input.agent)
+    )
+  }
+
+  expect(answers).toEqual(Array(input.repetitions ?? 1).fill(input.expected))
+  expect(ensure).not.toHaveBeenCalled()
+  expect(effects).toEqual({
+    storeOpened: false,
+    writeGateAttached: false,
+    reaperStarted: false
+  })
+  expect(getStructuredAgentSessionHost()).toBeNull()
+}
+
+describe('structured agent-session create-support probe', () => {
+  afterEach(() => {
+    setStructuredAgentSessionHost(null)
+    agentSessionPtyWriteGate.detachRecordLookup()
+    vi.restoreAllMocks()
+  })
+
+  it.each(['codex', 'claude'] as const)(
+    'answers %s support repeatedly without installing the host',
+    async (agent) => {
+      await expectSupportWithoutInstall({
+        agent,
+        location: { executionHostId: 'local', wslDistro: null },
+        expected: { supported: true },
+        repetitions: 3
+      })
+    }
+  )
+
+  it.each(['codex', 'claude'] as const)(
+    'still reports an unsupported remote %s location without installing the host',
+    async (agent) => {
+      await expectSupportWithoutInstall({
+        agent,
+        location: { executionHostId: 'ssh-host-1', wslDistro: null },
+        expected: { supported: false, reason: 'remote' }
+      })
+    }
+  )
+
+  it.each(['codex', 'claude'] as const)(
+    'still reports an unsupported WSL %s location without installing the host',
+    async (agent) => {
+      await expectSupportWithoutInstall({
+        agent,
+        location: { executionHostId: 'local', wslDistro: 'Ubuntu' },
+        expected: { supported: false, reason: 'wsl' }
+      })
+    }
+  )
+
+  it.each(['codex', 'claude'] as const)(
+    'supports a local folder workspace for %s without installing the host',
+    async (agent) => {
+      await expectSupportWithoutInstall({
+        agent,
+        location: {
+          executionHostId: 'local',
+          wslDistro: null,
+          workspaceKind: 'folder'
+        },
+        expected: { supported: true }
+      })
+    }
+  )
+
+  it('still installs and reconciles on startup when a store is already persisted', async () => {
+    const runtime = createRuntime({ executionHostId: 'local', wslDistro: null })
+    const { effects, ensure } = stubStructuredHostInstall(runtime)
+    const internal = runtime as unknown as {
+      hasPersistedStructuredAgentSessionStore: () => boolean
+      refreshMobileSessionPtyRecords: () => Promise<void>
+    }
+    internal.hasPersistedStructuredAgentSessionStore = () => true
+    internal.refreshMobileSessionPtyRecords = vi.fn(async () => {})
+
+    await runtime.prepareStructuredAgentSessionStartupRestoration()
+
+    expect(ensure).toHaveBeenCalledTimes(1)
+    expect(effects).toEqual({
+      storeOpened: true,
+      writeGateAttached: true,
+      reaperStarted: true
+    })
+    expect(
+      (getStructuredAgentSessionHost() as unknown as { reconcileRestartLeases: () => void })
+        .reconcileRestartLeases
+    ).toHaveBeenCalledTimes(1)
+  })
+})
diff --git a/src/main/shell-wrapper-generated-file-snapshot.test.ts b/src/main/shell-wrapper-generated-file-snapshot.test.ts
index ddbf1537984..36cd837e4fd 100644
--- a/src/main/shell-wrapper-generated-file-snapshot.test.ts
+++ b/src/main/shell-wrapper-generated-file-snapshot.test.ts
@@ -73,6 +73,7 @@ const CONTRACT_GLOBALS = new Set([
   'OPENCODE_CONFIG_DIR',
   'PATH',
   'PROMPT_COMMAND',
+  'PS1', // Bash appends its non-printing Readline readiness marker.
   'CURSOR',
   'ZDOTDIR',
   'precmd_functions',
diff --git a/src/main/startup/main-process-preflight.ts b/src/main/startup/main-process-preflight.ts
index 269eb2212e7..177a2357441 100644
--- a/src/main/startup/main-process-preflight.ts
+++ b/src/main/startup/main-process-preflight.ts
@@ -48,7 +48,7 @@ import {
 } from './single-instance-lock'
 import { setAppEnvironment } from '../../shared/app-environment'
 import { ElectronAppEnvironment } from '../host/electron-app-environment'
-import { installProcessTreeKillBreadcrumbObserver } from '../crash-reporting/self-initiated-tree-kill-log'
+import { installMainProcessTreeKillGate } from '../own-chromium-tree-kill-guard'
 import { setSecretStore } from '../../shared/secret-store'
 import { ElectronSecretStore } from '../host/electron-secret-store'
 import { setPtyHostBindings } from '../ipc/pty-host-bindings'
@@ -163,8 +163,8 @@ export function runMainProcessPreflight(options: MainProcessPreflightOptions): b
     })
   }
   // Why before any spawn: `signalProcessTree` is shared with the CLI and relay, so
-  // it can only reach the main-process breadcrumb store through a registered observer.
-  installProcessTreeKillBreadcrumbObserver()
+  // it can only reach the main-process guard and breadcrumb store once this is registered.
+  installMainProcessTreeKillGate()
   const isDev = is.dev
   configureDevUserDataPath(isDev)
   configureOrcaUserDataPathEnv()
diff --git a/src/main/text-generation/commit-message-text-generation-cancellation.test.ts b/src/main/text-generation/commit-message-text-generation-cancellation.test.ts
index 9cfde774384..820af710fb9 100644
--- a/src/main/text-generation/commit-message-text-generation-cancellation.test.ts
+++ b/src/main/text-generation/commit-message-text-generation-cancellation.test.ts
@@ -101,7 +101,7 @@ describe('generateCommitMessageFromContext', () => {
 
     cancelGenerateCommitMessageLocal('/repo')
 
-    expectChildTerminated(children[0]!)
+    await expectChildTerminated(children[0]!)
     expect(children[1]?.kill).not.toHaveBeenCalled()
 
     children[0]?.listeners.get('close')?.(null)
@@ -192,7 +192,7 @@ describe('generateCommitMessageFromContext', () => {
     cancelGeneratePullRequestFieldsLocal('/repo')
 
     expect(children[0]?.kill).not.toHaveBeenCalled()
-    expectChildTerminated(children[1]!)
+    await expectChildTerminated(children[1]!)
 
     const commitStdout = children[0]?.listeners.get('stdout:data')
     commitStdout?.(Buffer.from('Update README\n'))
@@ -250,7 +250,7 @@ describe('generateCommitMessageFromContext', () => {
     cancelGeneratePullRequestFieldsLocal('/repo')
     listeners.get('close')?.(null)
 
-    expectChildTerminated(child)
+    await expectChildTerminated(child)
     await expect(pullRequest).resolves.toEqual({
       success: false,
       error: 'Generation canceled.',
@@ -306,7 +306,7 @@ describe('generateCommitMessageFromContext', () => {
       )
 
       cancelGenerateCommitMessageLocal('/repo')
-      expectChildTerminated(child)
+      await expectChildTerminated(child)
       await Promise.resolve()
       await Promise.resolve()
       await Promise.resolve()
@@ -344,7 +344,7 @@ describe('generateCommitMessageFromContext', () => {
       error: 'Generation canceled.',
       canceled: true
     })
-    expectChildTerminated(firstChild)
+    await expectChildTerminated(firstChild)
 
     const second = generateCommitMessageFromContext(context, params, {
       kind: 'local',
@@ -377,7 +377,7 @@ describe('generateCommitMessageFromContext', () => {
     await vi.waitFor(() => expect(spawnMock).toHaveBeenCalledTimes(1))
     cancelGenerateCommitMessageLocal('/descendant-repo')
     await expect(first).resolves.toMatchObject({ canceled: true })
-    expectChildTerminated(firstChild)
+    await expectChildTerminated(firstChild)
 
     // SIGKILL reaches the codex process but not a grandchild that inherited its
     // stdout, so 'exit' arrives and 'close' never does.
diff --git a/src/main/text-generation/commit-message-text-generation-local-subprocess.test.ts b/src/main/text-generation/commit-message-text-generation-local-subprocess.test.ts
index c124cb85779..f73152255da 100644
--- a/src/main/text-generation/commit-message-text-generation-local-subprocess.test.ts
+++ b/src/main/text-generation/commit-message-text-generation-local-subprocess.test.ts
@@ -71,7 +71,7 @@ describe('generateCommitMessageFromContext', () => {
       error:
         'agent CLI command produced too much output. Check the agent CLI configuration and try again.'
     })
-    expectChildTerminated(child)
+    await expectChildTerminated(child)
   })
 
   it('passes prepared provider environment to local agent subprocesses', async () => {
diff --git a/src/main/text-generation/commit-message-text-generation-model-discovery.test.ts b/src/main/text-generation/commit-message-text-generation-model-discovery.test.ts
index 4bc1a720f05..9a1f932f0a0 100644
--- a/src/main/text-generation/commit-message-text-generation-model-discovery.test.ts
+++ b/src/main/text-generation/commit-message-text-generation-model-discovery.test.ts
@@ -325,7 +325,7 @@ describe('discoverCommitMessageModelsLocal', () => {
       await vi.advanceTimersByTimeAsync(60_000)
 
       await assertion
-      expectChildTerminated(child)
+      await expectChildTerminated(child)
       expect(child.stdout.listenerCount('data')).toBe(0)
       expect(child.stderr.listenerCount('data')).toBe(0)
       expect(child.listenerCount('error')).toBe(0)
@@ -352,7 +352,7 @@ describe('discoverCommitMessageModelsLocal', () => {
         success: false,
         error: 'Codex model discovery timed out after 60s.'
       })
-      expectChildTerminated(firstChild)
+      await expectChildTerminated(firstChild)
       expect(spawnMock).toHaveBeenCalledTimes(1)
 
       firstChild.emit('close', null)
@@ -413,7 +413,7 @@ describe('discoverCommitMessageModelsLocal', () => {
       success: false,
       error: 'Cursor returned too much model data.'
     })
-    expectChildTerminated(child)
+    await expectChildTerminated(child)
     expect(child.stdout.listenerCount('data')).toBe(0)
     expect(child.stderr.listenerCount('data')).toBe(0)
     expect(child.listenerCount('error')).toBe(0)
diff --git a/src/main/text-generation/commit-message-text-generation-test-harness.ts b/src/main/text-generation/commit-message-text-generation-test-harness.ts
index 21103d71f40..8ba925ef087 100644
--- a/src/main/text-generation/commit-message-text-generation-test-harness.ts
+++ b/src/main/text-generation/commit-message-text-generation-test-harness.ts
@@ -33,15 +33,17 @@ export function withPlatform<T>(platform: NodeJS.Platform, fn: () => T): T {
 // expectChildTerminated(child) with no extra argument.
 export function createChildTerminationExpectation(
   terminateWindowsProcessTreeMock: ReturnType<typeof vi.fn>
-): (child: { pid: number; kill: ReturnType<typeof vi.fn> }) => void {
-  return (child) => {
+): (child: { pid: number; kill: ReturnType<typeof vi.fn> }) => Promise<void> {
+  return async (child) => {
     if (process.platform === 'win32') {
       expect(terminateWindowsProcessTreeMock).toHaveBeenCalledWith(child.pid, {
         site: 'source-control-text-generation'
       })
-      expect(child.kill).not.toHaveBeenCalled()
-      return
     }
-    expect(child.kill).toHaveBeenCalledWith('SIGKILL')
+    // Every platform kills the root by its own handle. On win32 that is not a
+    // duplicate of the tree walk: it is what keeps a refused walk from resolving
+    // having killed nothing while the caller releases the managed-home lock. It
+    // runs after the walk there, so it can be a tick behind the caller.
+    await vi.waitFor(() => expect(child.kill).toHaveBeenCalledWith('SIGKILL'))
   }
 }
diff --git a/src/main/text-generation/source-control-local-process.ts b/src/main/text-generation/source-control-local-process.ts
index 170dead6b52..3f046494f0f 100644
--- a/src/main/text-generation/source-control-local-process.ts
+++ b/src/main/text-generation/source-control-local-process.ts
@@ -22,22 +22,25 @@ import type {
   TextGenerationOperation
 } from './source-control-text-generation-types'
 
-export function killSourceControlAgentProcess(
+export async function killSourceControlAgentProcess(
   child: SpawnedSourceControlAgentProcess
 ): Promise<void> {
   const pid = child.pid
   if (!pid) {
-    return Promise.resolve()
+    return
   }
   if (process.platform === 'win32') {
-    return terminateWindowsProcessTree(pid, { site: 'source-control-text-generation' })
+    // taskkill owns the tree, but the own-Chromium gate can refuse the
+    // pid-addressed walk; the handle-addressed root kill below cannot reach the
+    // recycled pid it refused, and callers release the managed-home lock on this
+    // promise, so it must not resolve having killed nothing.
+    await terminateWindowsProcessTree(pid, { site: 'source-control-text-generation' })
   }
   try {
     child.kill('SIGKILL')
   } catch {
     // The process may exit between the PID check and kill.
   }
-  return Promise.resolve()
 }
 
 export function runLocalSourceControlPlan(input: {
diff --git a/src/main/windows-live-tree-kill.win32.test.ts b/src/main/windows-live-tree-kill.win32.test.ts
new file mode 100644
index 00000000000..45563e82c89
--- /dev/null
+++ b/src/main/windows-live-tree-kill.win32.test.ts
@@ -0,0 +1,197 @@
+import { existsSync, mkdtempSync, readFileSync } from 'node:fs'
+import { tmpdir } from 'node:os'
+import { join } from 'node:path'
+import { spawn, ChildProcess } from 'node:child_process'
+import { subscribe, unsubscribe } from 'node:diagnostics_channel'
+import { afterAll, afterEach, beforeEach, describe, expect, it } from 'vitest'
+import { setAppEnvironment, type AppEnvironment } from '../shared/app-environment'
+import { setProcessTreeKillGate } from '../shared/child-process/process-tree-kill-gate'
+import { signalProcessTree } from '../shared/child-process/process-tree-termination'
+import { removeTreeSync } from '../shared/windows-transient-lock-removal'
+import {
+  findSelfInitiatedTreeKills,
+  resetSelfInitiatedTreeKillLogForTest
+} from './crash-reporting/self-initiated-tree-kill-log'
+import { installMainProcessTreeKillGate } from './own-chromium-tree-kill-guard'
+import { terminateWindowsProcessTree } from './windows-process-tree-kill'
+
+/**
+ * The unit tests pin the gate's decision against a mocked `taskkill`; this pins
+ * what that decision does to real Windows processes.
+ *
+ * Both are needed. Every claim the gate makes is about a mechanism the mocks
+ * cannot show: that `taskkill /T /F` actually reaps a detached grandchild, that
+ * a refusal actually leaves that tree standing, and that the handle-addressed
+ * root kill the refusal path falls back to actually reaps the root while
+ * orphaning its descendants — the asymmetry the PR discloses rather than fixes.
+ *
+ * Runs only on win32; skipped elsewhere.
+ */
+const describeOnWindows = process.platform === 'win32' ? describe : describe.skip
+
+/** Read live by the guard on every kill, so a case can flip it mid-test. */
+let orcaChromiumPids: number[] = []
+
+function appEnvironment(): AppEnvironment {
+  return {
+    getPath: () => process.cwd(),
+    getAppPath: () => process.cwd(),
+    getVersion: () => '0.0.0-live',
+    isPackaged: () => false,
+    onWillQuit: () => {},
+    exit: () => {},
+    getAppMetrics: (() =>
+      orcaChromiumPids.map((pid) => ({
+        pid,
+        type: 'Tab'
+      }))) as unknown as AppEnvironment['getAppMetrics']
+  }
+}
+
+function isAlive(pid: number): boolean {
+  try {
+    process.kill(pid, 0)
+    return true
+  } catch {
+    return false
+  }
+}
+
+const sleep = (ms: number): Promise<void> => new Promise((resolve) => setTimeout(resolve, ms))
+
+async function waitFor(predicate: () => boolean, timeoutMs = 10_000): Promise<boolean> {
+  const deadline = Date.now() + timeoutMs
+  while (Date.now() < deadline && !predicate()) {
+    await sleep(100)
+  }
+  return predicate()
+}
+
+let markerDirectory = ''
+let markerSequence = 0
+const spawnedRoots: ChildProcess[] = []
+const spawnedLeaves: number[] = []
+const observedSpawns: ChildProcess[] = []
+
+function observeSpawn(message: unknown): void {
+  if (
+    typeof message === 'object' &&
+    message !== null &&
+    'process' in message &&
+    message.process instanceof ChildProcess
+  ) {
+    observedSpawns.push(message.process)
+  }
+}
+
+/** A real root with a real grandchild; the grandchild reports its pid on disk. */
+async function spawnLiveTree(): Promise<{
+  child: ChildProcess
+  rootPid: number
+  leafPid: number
+}> {
+  const marker = join(markerDirectory, `leaf-${markerSequence++}.pid`)
+  const leafSource = `require('node:fs').writeFileSync(${JSON.stringify(marker)}, String(process.pid)); setTimeout(() => {}, 600000)`
+  // Non-detached Windows children can die with the root's libuv Job Object.
+  const rootSource = `require('node:child_process').spawn(process.execPath, ['-e', ${JSON.stringify(leafSource)}], { stdio: 'ignore', detached: true, windowsHide: true }); setTimeout(() => {}, 600000)`
+  const child = spawn(process.execPath, ['-e', rootSource], {
+    stdio: 'ignore',
+    windowsHide: true
+  })
+  spawnedRoots.push(child)
+  const rootPid = child.pid as number
+  expect(rootPid).toBeGreaterThan(0)
+  expect(await waitFor(() => existsSync(marker))).toBe(true)
+  const leafPid = Number(readFileSync(marker, 'utf8'))
+  spawnedLeaves.push(leafPid)
+  expect(await waitFor(() => isAlive(leafPid))).toBe(true)
+  return { child, rootPid, leafPid }
+}
+
+describeOnWindows('own-Chromium gate against real Windows process trees', () => {
+  beforeEach(() => {
+    markerDirectory ||= mkdtempSync(join(tmpdir(), 'orca-live-tree-kill-'))
+    resetSelfInitiatedTreeKillLogForTest()
+    orcaChromiumPids = []
+    setAppEnvironment(appEnvironment())
+    installMainProcessTreeKillGate()
+    observedSpawns.length = 0
+    subscribe('child_process', observeSpawn)
+  })
+
+  afterEach(async () => {
+    unsubscribe('child_process', observeSpawn)
+    orcaChromiumPids = []
+    for (const leafPid of spawnedLeaves.splice(0)) {
+      await terminateWindowsProcessTree(leafPid, { site: 'live-tree-kill-cleanup' })
+    }
+    for (const root of spawnedRoots.splice(0)) {
+      root.kill('SIGKILL')
+    }
+    setProcessTreeKillGate(null)
+  })
+
+  afterAll(() => {
+    if (markerDirectory) {
+      removeTreeSync(markerDirectory)
+    }
+  })
+
+  it('admitted: taskkill reaps the root and its detached grandchild, and the kill is recorded', async () => {
+    const { rootPid, leafPid } = await spawnLiveTree()
+
+    await terminateWindowsProcessTree(rootPid, { site: 'live-tree-kill-admit' })
+
+    expect(await waitFor(() => !isAlive(rootPid))).toBe(true)
+    expect(await waitFor(() => !isAlive(leafPid))).toBe(true)
+    expect(
+      findSelfInitiatedTreeKills(Date.now()).some(
+        (kill) => kill.pid === rootPid && kill.site === 'live-tree-kill-admit'
+      )
+    ).toBe(true)
+  })
+
+  it('refused: the tree survives, nothing is recorded, and the handle kill still reaps the root', async () => {
+    const { child, rootPid, leafPid } = await spawnLiveTree()
+    orcaChromiumPids = [rootPid]
+
+    await terminateWindowsProcessTree(rootPid, { site: 'live-tree-kill-refuse' })
+
+    await sleep(1_000)
+    expect(isAlive(rootPid)).toBe(true)
+    expect(isAlive(leafPid)).toBe(true)
+    expect(findSelfInitiatedTreeKills(Date.now())).toEqual([])
+
+    // The fallback every gated site runs after a refusal.
+    child.kill('SIGKILL')
+    expect(await waitFor(() => !isAlive(rootPid))).toBe(true)
+    // Let root-owned job cleanup finish before asserting independent survival.
+    await sleep(250)
+    // Disclosed asymmetry: a refusal orphans descendants rather than reaping them.
+    expect(isAlive(leafPid)).toBe(true)
+  })
+
+  it('signalProcessTree refused: the root goes by handle and the barrier reports unverified', async () => {
+    const { child, rootPid, leafPid } = await spawnLiveTree()
+    orcaChromiumPids = [rootPid]
+    observedSpawns.length = 0
+
+    await expect(signalProcessTree(child, 'SIGKILL')).resolves.toBe(false)
+
+    expect(observedSpawns).toHaveLength(0)
+    expect(await waitFor(() => !isAlive(rootPid))).toBe(true)
+    await sleep(250)
+    expect(isAlive(leafPid)).toBe(true)
+  })
+
+  it('signalProcessTree admitted: the whole tree goes and the barrier reports verified', async () => {
+    const { child, rootPid, leafPid } = await spawnLiveTree()
+    observedSpawns.length = 0
+
+    await expect(signalProcessTree(child, 'SIGKILL')).resolves.toBe(true)
+
+    expect(observedSpawns.map((child) => child.spawnfile)).toEqual(['taskkill'])
+    expect(await waitFor(() => !isAlive(rootPid))).toBe(true)
+    expect(await waitFor(() => !isAlive(leafPid))).toBe(true)
+  })
+})
diff --git a/src/main/windows-process-tree-kill.ts b/src/main/windows-process-tree-kill.ts
index ea7b756ada4..31e6b18da2a 100644
--- a/src/main/windows-process-tree-kill.ts
+++ b/src/main/windows-process-tree-kill.ts
@@ -11,8 +11,9 @@ export const WINDOWS_PROCESS_TREE_KILL_TIMEOUT_MS = 5_000
  * Best-effort: missing/already-dead roots still resolve so callers can finish
  * their own handle cleanup via killRoot.
  *
- * Nearly every main-process taskkill runs through here; the two account-login
- * teardowns keep their own spawn but share the same gate, so the refusal and the
+ * Most main-process taskkills run through here; the families that keep their own
+ * spawn (account-login teardowns, codex app-server deadline, git-command abort,
+ * notebook and precheck timeouts) share the same gate, so the refusal and the
  * breadcrumb live in `admitSelfInitiatedTreeKill` rather than in this function.
  */
 export function terminateWindowsProcessTree(
diff --git a/src/renderer/src/components/mobile/mobile-platform-copy.ts b/src/renderer/src/components/mobile/mobile-platform-copy.ts
index fd70176609d..cd6669891a3 100644
--- a/src/renderer/src/components/mobile/mobile-platform-copy.ts
+++ b/src/renderer/src/components/mobile/mobile-platform-copy.ts
@@ -22,7 +22,7 @@ const IOS_CHANNEL_COPY: Record<IosChannel, InstallCopy> = {
 
 const ANDROID_COPY: InstallCopy = {
   ctaLabel: 'Download APK',
-  url: 'https://github.com/stablyai/orca/releases/download/mobile-android-v0.0.46/app-release.apk'
+  url: 'https://github.com/stablyai/orca/releases/download/mobile-android-v0.0.47/app-release.apk'
 }
 
 export function getInstallCopy(platform: Platform, iosChannel: IosChannel): InstallCopy {
diff --git a/src/renderer/src/components/settings/MobileSettingsPane.tsx b/src/renderer/src/components/settings/MobileSettingsPane.tsx
index 2e98a5ccb43..ff8de2b16e5 100644
--- a/src/renderer/src/components/settings/MobileSettingsPane.tsx
+++ b/src/renderer/src/components/settings/MobileSettingsPane.tsx
@@ -13,7 +13,7 @@ export { getMobileSettingsPaneSearchEntries }
 
 const ORCA_IOS_APP_STORE_URL = 'https://apps.apple.com/app/orca-ide/id6766130217'
 const ORCA_ANDROID_APK_URL =
-  'https://github.com/stablyai/orca/releases/download/mobile-android-v0.0.46/app-release.apk'
+  'https://github.com/stablyai/orca/releases/download/mobile-android-v0.0.47/app-release.apk'
 
 export function MobileSettingsPane(): React.JSX.Element {
   const showMobileButton = useAppStore((s) => s.settings?.showMobileButton !== false)
diff --git a/src/shared/child-process/process-tree-kill-gate.ts b/src/shared/child-process/process-tree-kill-gate.ts
new file mode 100644
index 00000000000..420fbfeda9b
--- /dev/null
+++ b/src/shared/child-process/process-tree-kill-gate.ts
@@ -0,0 +1,43 @@
+/**
+ * Seam that lets the main process decide, and record, the tree-kills issued
+ * from code it does not own.
+ *
+ * Why a seam and not a direct call: `signalProcessTree` is the choke point every
+ * `runProcess` termination funnels through, and the codex app-server and
+ * ephemeral-VM kills are shared with the CLI — all of them live outside
+ * `src/main` and cannot import the own-Chromium guard or the crash breadcrumb
+ * store. Main registers the guard at startup; everywhere else this admits every
+ * kill and records nothing.
+ */
+
+/** Blast radius, not mechanism: `win-taskkill-tree` is addressed by pid and walks
+ *  whatever tree that pid has *now*, so it can land on a recycled pid that is
+ *  since one of Orca's own Chromium processes. A process group can only contain
+ *  processes Orca itself put there. */
+export type ProcessTreeKillScope = 'win-taskkill-tree' | 'posix-process-group'
+
+export type ProcessTreeKill = {
+  pid: number
+  site: string
+  scope: ProcessTreeKillScope
+}
+
+/** False means the caller must not walk that pid's tree — main is accounting for
+ *  it. Killing the root through its own child handle stays correct and required:
+ *  a handle cannot land on the recycled pid the refusal is about. */
+type ProcessTreeKillGate = (kill: ProcessTreeKill) => boolean
+
+let gate: ProcessTreeKillGate | null = null
+
+export function setProcessTreeKillGate(next: ProcessTreeKillGate | null): void {
+  gate = next
+}
+
+export function admitProcessTreeKill(kill: ProcessTreeKill): boolean {
+  try {
+    return gate?.(kill) ?? true
+  } catch {
+    // Diagnostics must never turn a successful termination into a failed one.
+    return true
+  }
+}
diff --git a/src/shared/child-process/process-tree-kill-observer.ts b/src/shared/child-process/process-tree-kill-observer.ts
deleted file mode 100644
index 8abf971798a..00000000000
--- a/src/shared/child-process/process-tree-kill-observer.ts
+++ /dev/null
@@ -1,37 +0,0 @@
-/**
- * Seam that lets the main process record the tree-kills issued from here.
- *
- * Why a seam and not a direct call: `signalProcessTree` is the choke point every
- * `runProcess` termination funnels through, but it lives in `src/shared` and so
- * runs in the CLI and relay too — it cannot import the main-process crash
- * breadcrumb store. Main registers the recorder at startup; everywhere else this
- * stays a no-op.
- */
-
-/** Blast radius, not mechanism: `win-taskkill-tree` is addressed by pid and walks
- *  whatever tree that pid has *now*, so it can land on a recycled pid that is
- *  since one of Orca's own Chromium processes. A process group can only contain
- *  processes Orca itself put there. */
-export type ProcessTreeKillScope = 'win-taskkill-tree' | 'posix-process-group'
-
-export type ProcessTreeKill = {
-  pid: number
-  site: string
-  scope: ProcessTreeKillScope
-}
-
-type ProcessTreeKillObserver = (kill: ProcessTreeKill) => void
-
-let observer: ProcessTreeKillObserver | null = null
-
-export function setProcessTreeKillObserver(next: ProcessTreeKillObserver | null): void {
-  observer = next
-}
-
-export function notifyProcessTreeKill(kill: ProcessTreeKill): void {
-  try {
-    observer?.(kill)
-  } catch {
-    // Diagnostics must never turn a successful termination into a failed one.
-  }
-}
diff --git a/src/shared/child-process/process-tree-termination.test.ts b/src/shared/child-process/process-tree-termination.test.ts
index cc3394fb5a3..10a4c725089 100644
--- a/src/shared/child-process/process-tree-termination.test.ts
+++ b/src/shared/child-process/process-tree-termination.test.ts
@@ -7,7 +7,7 @@ const { spawnMock } = vi.hoisted(() => ({ spawnMock: vi.fn() }))
 vi.mock('node:child_process', () => ({ spawn: spawnMock }))
 
 import { forceTerminateProcessTree, signalProcessTree } from './process-tree-termination'
-import { setProcessTreeKillObserver, type ProcessTreeKill } from './process-tree-kill-observer'
+import { setProcessTreeKillGate, type ProcessTreeKill } from './process-tree-kill-gate'
 
 function mockProcess(pid: number): ChildProcess {
   const child = new EventEmitter() as EventEmitter & {
@@ -103,11 +103,14 @@ describe('process-tree-kill breadcrumb seam', () => {
 
   beforeEach(() => {
     observed.length = 0
-    setProcessTreeKillObserver((kill) => observed.push(kill))
+    setProcessTreeKillGate((kill) => {
+      observed.push(kill)
+      return true
+    })
   })
 
   afterEach(() => {
-    setProcessTreeKillObserver(null)
+    setProcessTreeKillGate(null)
     spawnMock.mockReset()
     vi.restoreAllMocks()
   })
diff --git a/src/shared/child-process/process-tree-termination.ts b/src/shared/child-process/process-tree-termination.ts
index 15264b2f6ce..ffcb93b2245 100644
--- a/src/shared/child-process/process-tree-termination.ts
+++ b/src/shared/child-process/process-tree-termination.ts
@@ -1,5 +1,5 @@
 import { spawn as nodeSpawn, type ChildProcess } from 'node:child_process'
-import { notifyProcessTreeKill } from './process-tree-kill-observer'
+import { admitProcessTreeKill } from './process-tree-kill-gate'
 
 const PROBE_INTERVAL_MS = 25
 const SUBPROCESS_TIMEOUT_MS = 2_000
@@ -13,8 +13,17 @@ const MAX_PS_OUTPUT_BYTES = 8 * 1024 * 1024
  * leader would hand it to whatever group it inherited instead.
  *
  * Runs in every host — Electron main, the daemon, the relay, the CLI — so the
- * main-process own-Chromium guard cannot reach here; the exit check below is
- * what keeps the Windows branch off a pid that is no longer ours.
+ * own-Chromium guard arrives through `process-tree-kill-gate`, which main
+ * installs and every other host leaves admitting. The exit check below is what
+ * keeps the Windows branch off a pid that is no longer ours on those hosts.
+ *
+ * Both arms ask before walking the tree, so a refused pid never gets a
+ * pid-addressed kill; that also means the recorded crumb says "about to kill",
+ * not "killed". The root is still killed through its handle, which cannot reach
+ * the recycled pid the refusal was about, so a refusal is never a leak. Main's
+ * gate only ever refuses the `win-taskkill-tree` scope — a POSIX group holds
+ * only what Orca put in it — so the POSIX refusal arm is the seam's contract,
+ * not something any installed gate exercises today.
  */
 export function signalProcessTree(child: ChildProcess, signal?: NodeJS.Signals): Promise<boolean> {
   if (!child.pid) {
@@ -39,13 +48,20 @@ export function signalProcessTree(child: ChildProcess, signal?: NodeJS.Signals):
     }
     return taskkillTree(child, child.pid, signal)
   }
-  try {
-    process.kill(-child.pid, signal)
-    notifyProcessTreeKill({
+  if (
+    !admitProcessTreeKill({
       pid: child.pid,
       site: 'run-process-tree',
       scope: 'posix-process-group'
     })
+  ) {
+    // Same shape as the reaped-pid skip above: refuse the group, still kill the
+    // root by handle, and report unverified.
+    killRoot(child, signal)
+    return Promise.resolve(false)
+  }
+  try {
+    process.kill(-child.pid, signal)
     return Promise.resolve(true)
   } catch {
     return Promise.resolve(!processGroupExists(child.pid))
@@ -73,6 +89,13 @@ function taskkillTree(
   rootPid: number,
   signal?: NodeJS.Signals
 ): Promise<boolean> {
+  // Asked before the spawn, not after: a refusal has to prevent the taskkill.
+  if (
+    !admitProcessTreeKill({ pid: rootPid, site: 'run-process-tree', scope: 'win-taskkill-tree' })
+  ) {
+    killRoot(child, signal)
+    return Promise.resolve(false)
+  }
   return new Promise((resolve) => {
     let killer: ChildProcess
     try {
@@ -86,7 +109,6 @@ function taskkillTree(
       resolve(false)
       return
     }
-    notifyProcessTreeKill({ pid: rootPid, site: 'run-process-tree', scope: 'win-taskkill-tree' })
     let settled = false
     const finish = (fallback: boolean): void => {
       if (settled) {
diff --git a/src/shared/ephemeral-vm-recipe-process.ts b/src/shared/ephemeral-vm-recipe-process.ts
index b258a1b2704..30d44ac1dbc 100644
--- a/src/shared/ephemeral-vm-recipe-process.ts
+++ b/src/shared/ephemeral-vm-recipe-process.ts
@@ -1,5 +1,6 @@
 import { spawn, type ChildProcessWithoutNullStreams } from 'node:child_process'
 import type { EphemeralVmRecipeContext } from './ephemeral-vm-recipe-runner'
+import { admitProcessTreeKill } from './child-process/process-tree-kill-gate'
 
 const DEFAULT_MAX_CAPTURE_BYTES = 1024 * 1024
 const CANCEL_FORCE_KILL_DELAY_MS = 5_000
@@ -132,13 +133,26 @@ export async function runRecipeCommand(args: {
   })
 }
 
-function killRecipeProcess(child: ChildProcessWithoutNullStreams, force = false): void {
+/** Exported for the refusal-fallback test; the abort path is otherwise unreachable. */
+export function killRecipeProcess(child: ChildProcessWithoutNullStreams, force = false): void {
   const signal = force ? 'SIGKILL' : 'SIGTERM'
   if (process.platform === 'win32') {
     // Recipes run through `cmd.exe /c` (shell: true), so child.kill() would only
     // terminate the wrapper and orphan the actual recipe subprocess (e.g. a cloud
     // CLI mid-provision). taskkill /T walks and kills the whole tree.
     if (child.pid) {
+      if (
+        !admitProcessTreeKill({
+          pid: child.pid,
+          site: 'ephemeral-vm-recipe',
+          scope: 'win-taskkill-tree'
+        })
+      ) {
+        // Refusal blocks the tree walk, not the termination: the root kill is
+        // handle-addressed, so it cannot reach the recycled pid we refused.
+        child.kill(signal)
+        return
+      }
       const killer = spawn('taskkill', ['/pid', String(child.pid), '/t', '/f'], {
         windowsHide: true,
         stdio: 'ignore'