diff --git a/src/cli/runtime/status.test.ts b/src/cli/runtime/status.test.ts
index 4c62be8d977..68d6f392a40 100644
--- a/src/cli/runtime/status.test.ts
+++ b/src/cli/runtime/status.test.ts
@@ -2,7 +2,7 @@ import { mkdtempSync, writeFileSync } from 'node:fs'
 import { createServer, type Socket } from 'node:net'
 import { tmpdir } from 'node:os'
 import { join } from 'node:path'
-import { afterEach, describe, expect, it } from 'vitest'
+import { afterEach, describe, expect, it, vi } from 'vitest'
 import { getRuntimeMetadataPath } from '../../shared/runtime-bootstrap'
 import type { RuntimeStatus } from '../../shared/runtime-types'
 import { RuntimeClient } from './client'
@@ -86,6 +86,57 @@ describe.skipIf(process.platform === 'win32')('CLI runtime status', () => {
   })
 })
 
+// Why: `kill(pid, 0)` answers EPERM when the pid exists under another uid — an Orca the
+// CLI was pointed at with ORCA_USER_DATA_PATH, or one started with sudo. Reading that
+// refusal as absence reports a live app as a dead one
+// (docs/reference/ssh-execution-boundary.md).
+describe.skipIf(process.platform === 'win32')('CLI status pid fallback', () => {
+  async function statusWithUnreachableRuntime(
+    killError: NodeJS.ErrnoException
+  ): Promise<Awaited<ReturnType<RuntimeClient['getCliStatus']>>> {
+    const userDataPath = mkdtempSync(join(tmpdir(), 'orca-runtime-status-probe-'))
+    writeFileSync(
+      getRuntimeMetadataPath(userDataPath),
+      JSON.stringify({
+        runtimeId: 'runtime-unreachable',
+        pid: 424242,
+        // Nothing is listening here, so `status.get` fails and the pid probe decides.
+        transport: { kind: 'unix', endpoint: join(userDataPath, 'absent.sock') },
+        authToken: 'token',
+        startedAt: Date.now()
+      })
+    )
+    const killSpy = vi.spyOn(process, 'kill').mockImplementation(() => {
+      throw killError
+    })
+    try {
+      return await new RuntimeClient(userDataPath).getCliStatus()
+    } finally {
+      killSpy.mockRestore()
+    }
+  }
+
+  it('keeps an unsignalable app running rather than calling the bootstrap stale', async () => {
+    const status = await statusWithUnreachableRuntime(
+      Object.assign(new Error('kill EPERM'), { code: 'EPERM' })
+    )
+
+    expect(status.result.app).toMatchObject({ running: true, pid: 424242 })
+    expect(status.result.runtime.state).toBe('starting')
+    expect(status.result.graph.state).toBe('starting')
+  })
+
+  it('still reports a stale bootstrap when the host proves the pid is gone', async () => {
+    const status = await statusWithUnreachableRuntime(
+      Object.assign(new Error('kill ESRCH'), { code: 'ESRCH' })
+    )
+
+    expect(status.result.app).toMatchObject({ running: false, pid: null })
+    expect(status.result.runtime.state).toBe('stale_bootstrap')
+    expect(status.result.graph.state).toBe('not_running')
+  })
+})
+
 describe('projectRemoteAppStatus', () => {
   function remoteStatus(overrides: Partial<RuntimeStatus> = {}): RuntimeStatus {
     return {
diff --git a/src/cli/runtime/status.ts b/src/cli/runtime/status.ts
index 8736f4cc177..05f13ffae4b 100644
--- a/src/cli/runtime/status.ts
+++ b/src/cli/runtime/status.ts
@@ -106,7 +106,9 @@ function isProcessRunning(pid: number | null | undefined): boolean {
   try {
     process.kill(pid, 0)
     return true
-  } catch {
-    return false
+  } catch (error) {
+    // Why: only ESRCH proves the pid is gone. EPERM means it exists under another uid, and
+    // reporting that as `stale_bootstrap` calls a live Orca dead.
+    return (error as NodeJS.ErrnoException)?.code !== 'ESRCH'
   }
 }
diff --git a/src/relay/pty-handler-revive.test.ts b/src/relay/pty-handler-revive.test.ts
index e184cd56817..6dc2a8d4b30 100644
--- a/src/relay/pty-handler-revive.test.ts
+++ b/src/relay/pty-handler-revive.test.ts
@@ -518,6 +518,37 @@ describe('PtyHandler', () => {
     expect(JSON.parse(live).map((entry: { id: string }) => entry.id)).toEqual(['pty-21'])
   })
 
+  // Why: the pid gate is the one place revive turns an observation into "this pane is
+  // finished". `kill(pid, 0)` answers EPERM when the process exists under another uid, and
+  // the same ESRCH-only rule `reapPtyProvenExited` applies has to hold here
+  // (docs/reference/ssh-execution-boundary.md).
+  it('keeps a pane whose pid refuses the probe and drops only a proven-gone one', async () => {
+    const state = JSON.stringify([
+      { id: 'pty-30', pid: 424242, cols: 80, rows: 24, cwd: LIVE_CWD },
+      { id: 'pty-31', pid: 434343, cols: 80, rows: 24, cwd: LIVE_CWD }
+    ])
+    const killSpy = vi.spyOn(process, 'kill').mockImplementation((pid) => {
+      if (pid === 424242) {
+        throw Object.assign(new Error('kill EPERM'), { code: 'EPERM' })
+      }
+      if (pid === 434343) {
+        throw Object.assign(new Error('kill ESRCH'), { code: 'ESRCH' })
+      }
+      return true
+    })
+    try {
+      await dispatcher.callRequest('pty.revive', { state })
+    } finally {
+      killSpy.mockRestore()
+    }
+
+    expect(mockPtySpawn).toHaveBeenCalledTimes(1)
+    const live = (await dispatcher.callRequest('pty.serialize', {
+      ids: ['pty-30', 'pty-31']
+    })) as string
+    expect(JSON.parse(live).map((entry: { id: string }) => entry.id)).toEqual(['pty-30'])
+  })
+
   describe('a Windows relay reviving a WSL pane', () => {
     const worktreeId = 'r::/remote/wsl-worktree'
     const historyFile = join(
diff --git a/src/relay/pty-handler.ts b/src/relay/pty-handler.ts
index cdf436bca2a..e69e3c1da56 100644
--- a/src/relay/pty-handler.ts
+++ b/src/relay/pty-handler.ts
@@ -2907,10 +2907,10 @@ export class PtyHandler {
       if (this.ptys.has(entry.id) || this.pendingReviveIds.has(entry.id)) {
         continue
       }
-      // Only re-attach if the original process is still alive
-      try {
-        process.kill(entry.pid, 0)
-      } catch {
+      // Only re-attach if the host proves the original process is still there. `isProcessAlive`
+      // is ESRCH-only for the same reason `reapPtyProvenExited` is: a refusal this host cannot
+      // resolve is unverifiable, not absence (docs/reference/ssh-execution-boundary.md).
+      if (!Number.isInteger(entry.pid) || entry.pid <= 0 || !isProcessAlive(entry.pid)) {
         continue
       }
       const ownedPath = entry.worktreeId