diff --git a/src/main/daemon/terminal-host-session-create.ts b/src/main/daemon/terminal-host-session-create.ts
index 24f6cc2e867..e1c8a22e750 100644
--- a/src/main/daemon/terminal-host-session-create.ts
+++ b/src/main/daemon/terminal-host-session-create.ts
@@ -150,7 +150,23 @@ async function spawnAndPublishSession(
   deps.onSessionCreated(opts.sessionId, opts.agentSessionGeneration, session.isAlive)
   const token = session.attachClient(opts.streamClient)
 
-  if (opts.command && !subprocess.startupCommandDeliveredInShellArgs) {
+  const startupCommandWritten =
+    Boolean(opts.command) && !subprocess.startupCommandDeliveredInShellArgs
+  // Why: without this, a missing command and a lost one log identically.
+  // Length, never the text -- launches can carry credentials.
+  try {
+    deps.reportReadinessEvent?.('startup-command-delivery', {
+      sessionId: opts.sessionId,
+      written: startupCommandWritten,
+      hasCommand: Boolean(opts.command),
+      commandLength: opts.command?.length ?? 0,
+      viaShellArgs: subprocess.startupCommandDeliveredInShellArgs === true,
+      queuedByShellReadyBarrier: shellReadySupported
+    })
+  } catch {
+    // Diagnostics must never turn a live PTY into a failed create.
+  }
+  if (startupCommandWritten && opts.command) {
     const submit = process.platform === 'win32' ? '\r' : '\n'
     // Why: only Orca-wrapped shells advertise the paste-safe startup barrier.
     session.write(
diff --git a/src/main/daemon/terminal-host-startup.test.ts b/src/main/daemon/terminal-host-startup.test.ts
index fafa34eedc0..e7b7c7b4c09 100644
--- a/src/main/daemon/terminal-host-startup.test.ts
+++ b/src/main/daemon/terminal-host-startup.test.ts
@@ -54,3 +54,79 @@ describe('TerminalHost startup command terminator', () => {
     expect(sub.write).toHaveBeenCalledWith(sent)
   })
 })
+
+// Why: a missing command and a lost one used to log identically.
+describe('TerminalHost startup command delivery logging', () => {
+  let sub: SubprocessHandle
+  let events: { event: string; details: Record<string, unknown> }[]
+  let host: TerminalHost
+
+  beforeEach(() => {
+    sub = mockSubprocess()
+    events = []
+    host = new TerminalHost({
+      spawnSubprocess: () => sub,
+      reportReadinessEvent: (event, details) => events.push({ event, details })
+    })
+  })
+
+  const delivery = (): Record<string, unknown> =>
+    events.find((e) => e.event === 'startup-command-delivery')?.details ?? {}
+
+  it('records a written startup command', async () => {
+    await host.createOrAttach({
+      sessionId: 'delivery-written',
+      cols: 80,
+      rows: 24,
+      command: 'codex',
+      shellReadySupported: false,
+      streamClient: { onData: vi.fn(), onExit: vi.fn() }
+    })
+    expect(delivery()).toMatchObject({ written: true, hasCommand: true, commandLength: 5 })
+  })
+
+  it('records a session created with no startup command at all', async () => {
+    await host.createOrAttach({
+      sessionId: 'delivery-none',
+      cols: 80,
+      rows: 24,
+      shellReadySupported: false,
+      streamClient: { onData: vi.fn(), onExit: vi.fn() }
+    })
+    expect(delivery()).toMatchObject({ written: false, hasCommand: false, commandLength: 0 })
+    expect(sub.write).not.toHaveBeenCalled()
+  })
+
+  it('never logs the command text, which can carry credentials', async () => {
+    await host.createOrAttach({
+      sessionId: 'delivery-secret',
+      cols: 80,
+      rows: 24,
+      command: 'deploy --token=hunter2',
+      shellReadySupported: false,
+      streamClient: { onData: vi.fn(), onExit: vi.fn() }
+    })
+    expect(JSON.stringify(delivery())).not.toContain('hunter2')
+  })
+
+  it('still delivers the command when the diagnostic sink throws', async () => {
+    host = new TerminalHost({
+      spawnSubprocess: () => sub,
+      reportReadinessEvent: () => {
+        throw new Error('log sink unavailable')
+      }
+    })
+
+    await expect(
+      host.createOrAttach({
+        sessionId: 'delivery-sink-failure',
+        cols: 80,
+        rows: 24,
+        command: 'codex',
+        shellReadySupported: false,
+        streamClient: { onData: vi.fn(), onExit: vi.fn() }
+      })
+    ).resolves.toMatchObject({ isNew: true })
+    expect(sub.write).toHaveBeenCalledWith(`codex${process.platform === 'win32' ? '\r' : '\n'}`)
+  })
+})
diff --git a/src/shared/setup-agent-sequencing.test.ts b/src/shared/setup-agent-sequencing.test.ts
index 3d51b5b7476..fd567c145b0 100644
--- a/src/shared/setup-agent-sequencing.test.ts
+++ b/src/shared/setup-agent-sequencing.test.ts
@@ -9,6 +9,7 @@ import { getDefaultRepoHookSettings } from './constants'
 import {
   createSequencedSetupAgentCommands,
   createSetupAgentSequenceNonce,
+  SETUP_COMPLETE_MESSAGE,
   getSetupAgentSequenceShellForTests,
   resolveSetupAgentSequenceLaunchCommand,
   SETUP_AGENT_SEQUENCE_STARTUP_COMMAND_ENV,
@@ -89,6 +90,52 @@ describe('createSequencedSetupAgentCommands', () => {
     )
   })
 
+  it('announces success so the pane stops showing the waiting line', () => {
+    const commands = createSequencedSetupAgentCommands({
+      runnerScriptPath: '/repo/.git/orca/setup-runner.sh',
+      startupCommand: 'codex',
+      platform: 'posix',
+      nonce: 'nonce-1'
+    })
+    const script = commands.startupEnv?.ORCA_SEQUENCED_STARTUP_SCRIPT ?? ''
+    // Why ordering: `eval`/`exec` never returns, so a later message never renders.
+    expect(script.indexOf(SETUP_COMPLETE_MESSAGE)).toBeGreaterThan(-1)
+    expect(script.indexOf(SETUP_COMPLETE_MESSAGE)).toBeLessThan(
+      script.indexOf('eval "$ORCA_SEQUENCED_STARTUP_COMMAND"')
+    )
+  })
+
+  it('announces success on the native Windows gate too', () => {
+    const commands = createSequencedSetupAgentCommands({
+      runnerScriptPath: 'C:\\repo\\.git\\orca\\setup-runner.cmd',
+      platform: 'windows',
+      startupCommand: 'codex',
+      nonce: 'nonce-2'
+    })
+    const decoded = Buffer.from(
+      commands.startupCommand.split('-EncodedCommand ')[1] ?? '',
+      'base64'
+    ).toString('utf16le')
+    expect(decoded).toContain(SETUP_COMPLETE_MESSAGE)
+    expect(decoded.indexOf(SETUP_COMPLETE_MESSAGE)).toBeLessThan(
+      decoded.indexOf('Invoke-Expression $startup')
+    )
+  })
+
+  it('leaves the failure and timeout messages as the only other outcomes', () => {
+    const script =
+      createSequencedSetupAgentCommands({
+        runnerScriptPath: '/repo/.git/orca/setup-runner.sh',
+        startupCommand: 'codex',
+        platform: 'posix',
+        nonce: 'nonce-3'
+      }).startupEnv?.ORCA_SEQUENCED_STARTUP_SCRIPT ?? ''
+    // Silence on success is what made a healthy worktree look stuck.
+    expect(script).toContain(SETUP_COMPLETE_MESSAGE)
+    expect(script).toContain('Setup failed; skipping agent startup.')
+    expect(script).toContain('Timed out waiting for setup before starting agent.')
+  })
+
   it('keeps the POSIX terminal submission below the canonical input floor', () => {
     const result = createSequencedSetupAgentCommands({
       runnerScriptPath: `/repo/${'nested-worktree/'.repeat(100)}setup-runner.sh`,
diff --git a/src/shared/setup-agent-sequencing.ts b/src/shared/setup-agent-sequencing.ts
index b93fe9c8306..7108360f645 100644
--- a/src/shared/setup-agent-sequencing.ts
+++ b/src/shared/setup-agent-sequencing.ts
@@ -8,6 +8,8 @@ import {
 } from './setup-runner-command'
 
 const DEFAULT_WAIT_TIMEOUT_SECONDS = 2 * 60 * 60
+// Exported so the gate and its tests share one definition.
+export const SETUP_COMPLETE_MESSAGE = 'Setup finished; starting agent.'
 export const SETUP_AGENT_SEQUENCE_STARTUP_COMMAND_ENV = 'ORCA_SEQUENCED_STARTUP_COMMAND'
 export const SETUP_AGENT_SEQUENCE_STARTUP_SCRIPT_ENV = 'ORCA_SEQUENCED_STARTUP_SCRIPT'
 
@@ -126,7 +128,9 @@ function buildPosixStartupScript(
     `IFS=: read -r seen status < ${marker} || true;`,
     `if [ "$seen" = ${nonceValue} ]; then`,
     `rm -f ${marker} ${tmp} 2>/dev/null;`,
-    `if [ "$status" = "0" ]; then if [ -n "\${${SETUP_AGENT_SEQUENCE_STARTUP_COMMAND_ENV}:-}" ]; then eval "\$${SETUP_AGENT_SEQUENCE_STARTUP_COMMAND_ENV}"; exit "$?"; else ${startupSuccessCommand}; fi; fi;`,
+    // Why: failure and timeout announce themselves; a silent success left
+    // "Waiting for setup..." as the pane's last line forever.
+    `if [ "$status" = "0" ]; then echo ${quotePosixArg(SETUP_COMPLETE_MESSAGE)} >&2; if [ -n "\${${SETUP_AGENT_SEQUENCE_STARTUP_COMMAND_ENV}:-}" ]; then eval "\$${SETUP_AGENT_SEQUENCE_STARTUP_COMMAND_ENV}"; exit "$?"; else ${startupSuccessCommand}; fi; fi;`,
     'echo "Setup failed; skipping agent startup." >&2;',
     'exit "${status:-1}";',
     'fi;',
@@ -247,6 +251,7 @@ function buildWindowsStartupCommand(
     '        [Console]::Error.WriteLine("Missing sequenced startup command.")',
     '        exit 1',
     '      }',
+    `      [Console]::Error.WriteLine(${quotePowerShellString(SETUP_COMPLETE_MESSAGE)})`,
     '      Invoke-Expression $startup',
     '      if ($global:LASTEXITCODE -ne $null) { exit $global:LASTEXITCODE }',
     '      if (-not $?) { exit 1 }',