fix(windows): mark PowerShell startup command boundaries with OSC 133 C/D (#18182)

A startup command embedded in the PowerShell -EncodedCommand payload runs
before the first prompt, and the prompt wrapper suppresses 133;D until it
has printed once. An agent launched this way exited with no
command-finished boundary, so its pane was never retired.

Emit 133;C before the embedded startup command and prime the prompt latch
so the first prompt reports 133;D with the exit code. Stdin-typed startup
commands keep readline's own marks. The encoded-command budget grows by
the mark's size so real commands keep the prior limit.

Co-authored-by: Neil <4138956+nwparker@users.noreply.github.com>

src/main/powershell-osc133-bootstrap.ts

@@ -93,6 +93,11 @@ export function getPowerShellOsc133Bootstrap(): string {
   return POWERSHELL_OSC133_BOOTSTRAP_PAYLOAD
 }
 
+// Startup commands run before the first prompt, which suppresses 133;D; mark them like typed commands.
+export function getPowerShellOsc133StartupCommandMark(): string {
+  return 'if (Test-Path variable:global:__OrcaOsc133State) { [Console]::Write("$([char]27)]133;C$([char]7)"); $Global:__OrcaOsc133State.HasSeenPrompt = $true }'
+}
+
 export function isPowerShellExecutableName(shellName: string): boolean {
   const normalized = shellName.toLowerCase()
   return (

src/main/providers/windows-shell-args.test.ts

@@ -9,6 +9,7 @@ import { resolveWindowsShellLaunchArgs } from './windows-shell-args'
 import { getShellReadyWrapperRoot } from './local-pty-shell-ready-wrapper-root'
 
 const CODEX_LAUNCH_PREFLIGHT = 'C:\\Program Files\\Orca\\orca.exe'
+const POWERSHELL_STARTUP_COMMAND_C_MARK = '[Console]::Write("$([char]27)]133;C$([char]7)")'
 const CMD_CODEX_LAUNCH_PREFLIGHT =
   'if defined ORCA_CODEX_LAUNCH_PREFLIGHT call %ORCA_CODEX_LAUNCH_PREFLIGHT_CMD_QUOTE%%ORCA_CODEX_LAUNCH_PREFLIGHT%%ORCA_CODEX_LAUNCH_PREFLIGHT_CMD_QUOTE% agent hooks prepare-codex > nul 2>&1'
 
@@ -200,6 +201,10 @@ describe('resolveWindowsShellLaunchArgs', () => {
     expect(command).toContain('function Global:prompt')
     expect(command).toContain(expectedPowerShellRestoreCwdCommand("'C:\\Users\\alice'"))
     expect(command.trimEnd().endsWith("& 'codex' '--no-alt-screen'")).toBe(true)
+    // Without the mark, the first prompt after the agent exits withholds 133;D (#18180).
+    expect(command).toContain(
+      `${POWERSHELL_STARTUP_COMMAND_C_MARK}; $Global:__OrcaOsc133State.HasSeenPrompt = $true }\n& 'codex' '--no-alt-screen'`
+    )
   })
 
   it('preserves complex PowerShell startup command text through EncodedCommand', () => {
@@ -230,9 +235,10 @@ describe('resolveWindowsShellLaunchArgs', () => {
 
     expect(result.startupCommandDeliveredInShellArgs).toBeUndefined()
     expect(result.shellArgs).toEqual(['-NoLogo', '-NoExit', '-EncodedCommand', expect.any(String)])
-    expect(decodePowerShellCommand(result)).toContain(
-      expectedPowerShellRestoreCwdCommand("'C:\\Users\\alice'")
-    )
+    const command = decodePowerShellCommand(result)
+    expect(command).toContain(expectedPowerShellRestoreCwdCommand("'C:\\Users\\alice'"))
+    // Stdin-typed commands get readline's 133;C; an early latch would emit a false 133;D.
+    expect(command).not.toContain(POWERSHELL_STARTUP_COMMAND_C_MARK)
   })
 
   it('handles pwsh.exe (PowerShell Core) the same as Windows PowerShell', () => {

src/main/providers/windows-shell-args.ts

@@ -10,14 +10,16 @@ import { getBashWrapperLaunchArgs } from './local-pty-shell-ready'
 import { ensureShellReadyWrappersAt } from './local-pty-shell-ready-wrapper-generation'
 import {
   encodePowerShellCommand,
-  getPowerShellOsc133Bootstrap
+  getPowerShellOsc133Bootstrap,
+  getPowerShellOsc133StartupCommandMark
 } from '../powershell-osc133-bootstrap'
 import { quoteStartupArg } from '../../shared/tui-agent-startup-shell'
 
 /** cmd.exe's own documented ceiling; callers that go through sshd budget below it. */
 export const CMD_EXE_COMMAND_LINE_MAX_CHARS = 8191
 const STARTUP_COMMAND_TEXT_MAX_CHARS = 6000
-const POWERSHELL_ENCODED_COMMAND_ARG_MAX_CHARS = 28_000
+// Includes ~400 encoded chars for the startup command mark so real commands keep the prior budget.
+const POWERSHELL_ENCODED_COMMAND_ARG_MAX_CHARS = 28_400
 const CMD_UTF8_SETUP_COMMAND = 'chcp 65001 > nul'
 export const ORCA_CODEX_LAUNCH_PREFLIGHT_CMD_QUOTE_ENV = 'ORCA_CODEX_LAUNCH_PREFLIGHT_CMD_QUOTE'
 const CMD_CODEX_LAUNCH_PREFLIGHT = `if defined ORCA_CODEX_LAUNCH_PREFLIGHT call %${ORCA_CODEX_LAUNCH_PREFLIGHT_CMD_QUOTE_ENV}%%ORCA_CODEX_LAUNCH_PREFLIGHT%%${ORCA_CODEX_LAUNCH_PREFLIGHT_CMD_QUOTE_ENV}% agent hooks prepare-codex > nul 2>&1`
@@ -88,7 +90,7 @@ function getPowerShellEncodedCommand(
     return { encodedCommand: encodePowerShellCommand(bootstrap) }
   }
 
-  const command = `${bootstrap}\n${startupCommand}`
+  const command = `${bootstrap}\n${getPowerShellOsc133StartupCommandMark()}\n${startupCommand}`
   const encodedCommand = encodePowerShellCommand(command)
   // UTF-16/base64 expands payloads; leave margin under CreateProcess 32,767-character limit.
   if (encodedCommand.length > POWERSHELL_ENCODED_COMMAND_ARG_MAX_CHARS) {

src/main/runtime/terminal-command-paint.ts

@@ -52,7 +52,7 @@ export function observeTerminalCommandPaint(
   record.commandPaint.observe(data, normalizedText)
 }
 
-/** Without markers (older fish, relay zsh, unwrapped shells, Windows command args), any output is the only paint evidence. */
+/** Without markers (older fish, relay zsh, unwrapped shells, cmd.exe /K startup args), any output is the only paint evidence. */
 export function hasTerminalCommandPainted(record: TerminalCommandPaintRecord): boolean {
   return record.commandPaint?.hasPainted() ?? true
 }