diff --git a/src/main/daemon/pty-subprocess.ts b/src/main/daemon/pty-subprocess.ts
index c47f5c6c108..8e1f7024891 100644
--- a/src/main/daemon/pty-subprocess.ts
+++ b/src/main/daemon/pty-subprocess.ts
@@ -64,6 +64,7 @@ import { getAgentForegroundContextPaths } from '../providers/agent-foreground-co
 import { assertSafeAgentStartupCwd, resolveSafePtyDefaultCwd } from '../providers/pty-default-cwd'
 import { ORCA_HERMES_STARTUP_QUERY_ENV } from '../../shared/hermes-startup-query'
 import type { TuiAgent } from '../../shared/types'
+import { forceKillPosixPtyProcessGroups } from '../pty/posix-pty-process-groups'
 
 const PANE_IDENTITY_ENV_KEYS = [
   'ORCA_PANE_KEY',
@@ -1220,7 +1221,9 @@ export function createPtySubprocess(opts: PtySubprocessOptions): SubprocessHandl
         return
       }
       try {
-        process.kill(proc.pid, 'SIGKILL')
+        forceKillPosixPtyProcessGroups(proc.pid, () => {
+          process.kill(proc.pid, 'SIGKILL')
+        })
       } catch (signalError) {
         try {
           proc.kill()
diff --git a/src/main/providers/local-pty-provider.ts b/src/main/providers/local-pty-provider.ts
index f44cae2ea08..9cbdbaa6095 100644
--- a/src/main/providers/local-pty-provider.ts
+++ b/src/main/providers/local-pty-provider.ts
@@ -55,6 +55,7 @@ import { resolveAgentForegroundProcessWithAvailability } from './agent-foregroun
 import { getAgentForegroundContextPaths } from './agent-foreground-context-paths'
 import { recognizeAgentProcessFromCommandLine } from '../../shared/agent-process-recognition'
 import { readWindowsConptyProcessIds } from './windows-conpty-process-membership'
+import { forceKillPosixPtyProcessGroups } from '../pty/posix-pty-process-groups'
 import { shouldUseShellReadyStartupDelivery } from '../../shared/codex-startup-delivery'
 import { assertSafeAgentStartupCwd, resolveSafePtyDefaultCwd } from './pty-default-cwd'
 import { ORCA_HERMES_STARTUP_QUERY_ENV } from '../../shared/hermes-startup-query'
@@ -232,7 +233,11 @@ function killLocalPtyProcess(proc: pty.IPty, immediate: boolean): void {
     proc.kill()
     return
   }
-  proc.kill(immediate ? 'SIGKILL' : 'SIGTERM')
+  if (!immediate) {
+    proc.kill('SIGTERM')
+    return
+  }
+  forceKillPosixPtyProcessGroups(proc.pid, () => proc.kill('SIGKILL'))
 }
 
 function armLocalPtyForceKill(
diff --git a/src/main/pty/posix-pty-process-groups.integration.test.ts b/src/main/pty/posix-pty-process-groups.integration.test.ts
new file mode 100644
index 00000000000..f8b191f9856
--- /dev/null
+++ b/src/main/pty/posix-pty-process-groups.integration.test.ts
@@ -0,0 +1,94 @@
+import { execFileSync } from 'node:child_process'
+import * as pty from 'node-pty'
+import { expect, it } from 'vitest'
+import { forceKillPosixPtyProcessGroups } from './posix-pty-process-groups'
+
+type TaggedProcess = { pid: number; pgid: number }
+
+const itOnPosix = process.platform === 'win32' ? it.skip : it
+
+function findTaggedProcesses(token: string): TaggedProcess[] {
+  const output = execFileSync('ps', ['-axo', 'pid=,pgid=,state=,command='], {
+    encoding: 'utf8'
+  })
+  const matches: TaggedProcess[] = []
+  for (const line of output.split(/\r?\n/)) {
+    if (!line.includes(token)) {
+      continue
+    }
+    const match = /^\s*(\d+)\s+(\d+)\s+(\S+)\s+/.exec(line)
+    if (match && !match[3].includes('Z')) {
+      matches.push({ pid: Number(match[1]), pgid: Number(match[2]) })
+    }
+  }
+  return matches
+}
+
+async function waitFor(
+  predicate: () => boolean,
+  timeoutMs = 5_000,
+  intervalMs = 25
+): Promise<void> {
+  const deadline = Date.now() + timeoutMs
+  while (!predicate()) {
+    if (Date.now() >= deadline) {
+      throw new Error('Timed out waiting for PTY process state')
+    }
+    await new Promise((resolve) => setTimeout(resolve, intervalMs))
+  }
+}
+
+function cleanupTaggedProcesses(token: string): void {
+  for (const pgid of new Set(findTaggedProcesses(token).map((process) => process.pgid))) {
+    try {
+      process.kill(-pgid, 'SIGKILL')
+    } catch {
+      // The tagged test group may already be gone.
+    }
+  }
+}
+
+function readProcessGroup(pid: number): number {
+  return Number(execFileSync('ps', ['-p', String(pid), '-o', 'pgid='], { encoding: 'utf8' }).trim())
+}
+
+itOnPosix(
+  'reaps a foreground job that ignores terminal shutdown signals',
+  async () => {
+    const token = `ORCA_PTY_GROUP_TEST_${process.pid}_${Date.now()}`
+    const proc = pty.spawn('/bin/sh', [], {
+      name: 'xterm-256color',
+      cols: 80,
+      rows: 24,
+      cwd: process.cwd(),
+      env: process.env as Record<string, string>
+    })
+    const exited = new Promise<void>((resolve) => proc.onExit(() => resolve()))
+
+    try {
+      proc.write(`/bin/sh -lc 'trap "" HUP TERM; while :; do sleep 60; done' ${token}\n`)
+      await waitFor(() => findTaggedProcesses(token).length > 0)
+
+      const tagged = findTaggedProcesses(token)
+      const rootProcessGroup = readProcessGroup(proc.pid)
+      expect(tagged.some((process) => process.pgid !== rootProcessGroup)).toBe(true)
+
+      forceKillPosixPtyProcessGroups(proc.pid, () => proc.kill('SIGKILL'))
+      await Promise.race([
+        exited,
+        new Promise<never>((_, reject) =>
+          setTimeout(() => reject(new Error('PTY leader did not exit')), 5_000)
+        )
+      ])
+      await waitFor(() => findTaggedProcesses(token).length === 0)
+    } finally {
+      cleanupTaggedProcesses(token)
+      try {
+        proc.kill('SIGKILL')
+      } catch {
+        // node-pty may already have reaped and disposed the leader.
+      }
+    }
+  },
+  10_000
+)
diff --git a/src/main/pty/posix-pty-process-groups.test.ts b/src/main/pty/posix-pty-process-groups.test.ts
new file mode 100644
index 00000000000..59c287a303a
--- /dev/null
+++ b/src/main/pty/posix-pty-process-groups.test.ts
@@ -0,0 +1,90 @@
+import { describe, expect, it, vi } from 'vitest'
+import {
+  forceKillPosixPtyProcessGroups,
+  getPosixPtyProcessGroups
+} from './posix-pty-process-groups'
+
+const TABLE = `
+  100  100 ttys001
+  101  101 ttys001
+  102  101 ttys001
+  103  103 ttys001
+  200  200 ttys002
+  300  300 ??
+`
+
+describe('POSIX PTY process-group termination', () => {
+  it('returns every group attached to the root PTY with the root group last', () => {
+    expect(getPosixPtyProcessGroups(TABLE, 100, 999)).toEqual([101, 103, 100])
+  })
+
+  it('refuses an unbound root or a PTY shared with Orca itself', () => {
+    expect(getPosixPtyProcessGroups(TABLE, 300, 999)).toBeNull()
+    expect(getPosixPtyProcessGroups(TABLE, 100, 102)).toBeNull()
+    expect(getPosixPtyProcessGroups(TABLE, 999, 998)).toBeNull()
+  })
+
+  it('kills foreground and background groups before the PTY leader', () => {
+    const fallback = vi.fn()
+    const signalProcessGroup = vi.fn()
+
+    forceKillPosixPtyProcessGroups(100, fallback, {
+      platform: 'darwin',
+      currentPid: 999,
+      readProcessTable: () => TABLE,
+      signalProcessGroup
+    })
+
+    expect(signalProcessGroup.mock.calls.map(([pgid]) => pgid)).toEqual([101, 103, 100])
+    expect(fallback).not.toHaveBeenCalled()
+  })
+
+  it('falls back when the process table cannot prove PTY ownership', () => {
+    const fallback = vi.fn()
+
+    forceKillPosixPtyProcessGroups(100, fallback, {
+      platform: 'linux',
+      currentPid: 102,
+      readProcessTable: () => TABLE,
+      signalProcessGroup: vi.fn()
+    })
+
+    expect(fallback).toHaveBeenCalledOnce()
+  })
+
+  it('ignores groups that exited after the snapshot but preserves real signal errors', () => {
+    const gone = Object.assign(new Error('gone'), { code: 'ESRCH' })
+    const denied = Object.assign(new Error('denied'), { code: 'EPERM' })
+    const signalProcessGroup = vi
+      .fn<(pgid: number) => void>()
+      .mockImplementationOnce(() => {
+        throw gone
+      })
+      .mockImplementationOnce(() => {
+        throw denied
+      })
+
+    expect(() =>
+      forceKillPosixPtyProcessGroups(100, vi.fn(), {
+        platform: 'darwin',
+        currentPid: 999,
+        readProcessTable: () => TABLE,
+        signalProcessGroup
+      })
+    ).toThrow('denied')
+    expect(signalProcessGroup).toHaveBeenCalledTimes(3)
+  })
+
+  it('uses the existing fallback on Windows without reading ps', () => {
+    const fallback = vi.fn()
+    const readProcessTable = vi.fn(() => TABLE)
+
+    forceKillPosixPtyProcessGroups(100, fallback, {
+      platform: 'win32',
+      readProcessTable
+    })
+
+    expect(fallback).toHaveBeenCalledOnce()
+    expect(readProcessTable).not.toHaveBeenCalled()
+  })
+})
diff --git a/src/main/pty/posix-pty-process-groups.ts b/src/main/pty/posix-pty-process-groups.ts
new file mode 100644
index 00000000000..21b18808d6d
--- /dev/null
+++ b/src/main/pty/posix-pty-process-groups.ts
@@ -0,0 +1,130 @@
+import { execFileSync } from 'node:child_process'
+
+const PROCESS_TABLE_TIMEOUT_MS = 1_000
+const PROCESS_TABLE_MAX_BYTES = 1024 * 1024
+
+type ProcessRow = {
+  pid: number
+  pgid: number
+  tty: string
+}
+
+export type PosixPtyProcessGroupTerminationDeps = {
+  platform?: NodeJS.Platform
+  currentPid?: number
+  readProcessTable?: () => string
+  signalProcessGroup?: (pgid: number) => void
+}
+
+function runPs(args: string[]): string {
+  return execFileSync('ps', args, {
+    encoding: 'utf8',
+    timeout: PROCESS_TABLE_TIMEOUT_MS,
+    maxBuffer: PROCESS_TABLE_MAX_BYTES
+  })
+}
+
+function readPtyProcessTable(rootPid: number): string {
+  const root = runPs(['-p', String(rootPid), '-o', 'pid=,pgid=,tty='])
+  const rootRow = parseProcessRows(root).find((row) => row.pid === rootPid)
+  if (!rootRow || rootRow.tty === '?' || rootRow.tty === '??') {
+    return root
+  }
+  // Why: a whole-host `ps -ax` takes nearly a second on large machines. TTY
+  // selection keeps forced terminal teardown proportional to one terminal.
+  return `${root}\n${runPs(['-t', rootRow.tty, '-o', 'pid=,pgid=,tty='])}`
+}
+
+function parseProcessRows(output: string): ProcessRow[] {
+  const rows: ProcessRow[] = []
+  for (const line of output.split(/\r?\n/)) {
+    const match = /^\s*(\d+)\s+(\d+)\s+(\S+)/.exec(line)
+    if (!match) {
+      continue
+    }
+    const pid = Number(match[1])
+    const pgid = Number(match[2])
+    if (pid > 0 && pgid > 1) {
+      rows.push({ pid, pgid, tty: match[3] })
+    }
+  }
+  return rows
+}
+
+export function getPosixPtyProcessGroups(
+  output: string,
+  rootPid: number,
+  currentPid = process.pid
+): number[] | null {
+  const rows = parseProcessRows(output)
+  const root = rows.find((row) => row.pid === rootPid)
+  if (!root || root.tty === '?' || root.tty === '??') {
+    return null
+  }
+  // Why: a development daemon can inherit its launch TTY. Never group-signal
+  // when Orca itself shares the PTY; fall back to the already-scoped root kill.
+  if (rows.some((row) => row.pid === currentPid && row.tty === root.tty)) {
+    return null
+  }
+  const groups = new Set(rows.filter((row) => row.tty === root.tty).map((row) => row.pgid))
+  if (!groups.has(root.pgid)) {
+    return null
+  }
+  return [...groups].sort((left, right) => {
+    if (left === root.pgid) {
+      return 1
+    }
+    if (right === root.pgid) {
+      return -1
+    }
+    return left - right
+  })
+}
+
+function isProcessAlreadyGone(error: unknown): boolean {
+  return (error as NodeJS.ErrnoException | undefined)?.code === 'ESRCH'
+}
+
+/** Force-kill every process group still attached to one POSIX PTY. */
+export function forceKillPosixPtyProcessGroups(
+  rootPid: number,
+  fallback: () => void,
+  deps: PosixPtyProcessGroupTerminationDeps = {}
+): void {
+  if ((deps.platform ?? process.platform) === 'win32') {
+    fallback()
+    return
+  }
+  let groups: number[] | null
+  try {
+    groups = getPosixPtyProcessGroups(
+      (deps.readProcessTable ?? (() => readPtyProcessTable(rootPid)))(),
+      rootPid,
+      deps.currentPid ?? process.pid
+    )
+  } catch {
+    groups = null
+  }
+  if (!groups || groups.length === 0) {
+    fallback()
+    return
+  }
+
+  const signalProcessGroup =
+    deps.signalProcessGroup ?? ((pgid: number) => process.kill(-pgid, 'SIGKILL'))
+  let firstError: unknown
+  for (const pgid of groups) {
+    try {
+      signalProcessGroup(pgid)
+    } catch (error) {
+      // Why: the PTY exit callback may reap a group between `ps` and killpg.
+      // ESRCH is proof that this captured owner is already gone, not failure.
+      if (!isProcessAlreadyGone(error) && firstError === undefined) {
+        firstError = error
+      }
+    }
+  }
+  if (firstError !== undefined) {
+    throw firstError
+  }
+}
diff --git a/src/relay/pty-handler.ts b/src/relay/pty-handler.ts
index 4aac93d2a5c..c1de6809c15 100644
--- a/src/relay/pty-handler.ts
+++ b/src/relay/pty-handler.ts
@@ -36,6 +36,7 @@ import {
   mergeGitConfigEnvProtocol
 } from '../shared/git-credential-prompt-env'
 import { isTuiAgent } from '../shared/tui-agent-config'
+import { forceKillPosixPtyProcessGroups } from '../main/pty/posix-pty-process-groups'
 
 // Why: node-pty is a native addon that may not be installed on the remote.
 // Dynamic import keeps the require() lazy so loadPty() returns null gracefully
@@ -108,6 +109,10 @@ function killPtyProcess(pty: IPty, signal: string): void {
     pty.kill()
     return
   }
+  if (signal === 'SIGKILL') {
+    forceKillPosixPtyProcessGroups(pty.pid, () => pty.kill(signal))
+    return
+  }
   pty.kill(signal)
 }