test(plan): cover the final-state tails and refresh the TUI golden

The idle /plan and /plan off command paths pin the immediate-commit copy;
the chip's dead leaving/locked guard is deleted (both states disable the
button, so no click reaches the handler); the multi-turn TUI golden is
re-recorded keyless over the idle-commit wording and the standalone
plan/mode narration ordering.

examples/tui-agent/tests/snapshots/multi-turn-conversation/terminal.expected.txt

@@ -15,8 +15,8 @@ buffer
   style 0-2 fg=bright-blue bold underline
 5| "Reply with exactly the word: ONE. No tools.                                                         "
 6| <blank>
-7| "Entering plan mode (applies from the next step). Use /plan off to leave.                            "
+7| "Plan mode on. Use /plan off to leave.                                                               "
-  style 0-71 fg=bright-black
+  style 0-36 fg=bright-black
 8| <blank>
 9| "Assistant                                                                                           "
   style 0-8 fg=bright-magenta bold underline
@@ -28,17 +28,17 @@ buffer
 13| "Model wait 0.0s · Completed 2026-07-21 12:00:00                                                     "
   style 0-46 dim
 14| <blank>
-15| "Leaving plan mode (applies from the next step).                                                     "
+15| "Context · plan-mode                                                                                 "
-  style 0-46 fg=bright-black
-16| <blank>
-17| "You                                                                                                 "
-  style 0-2 fg=bright-blue bold underline
-18| "Reply with exactly the word: TWO. No tools.                                                         "
-19| <blank>
-20| "Context · plan-mode                                                                                 "
   style 0-18 dim
-21| "The user switched this session back to the default mode.                                            "
+16| "The user switched this session back to the default mode.                                            "
   style 0-55 fg=bright-black
+17| <blank>
+18| "Plan mode off.                                                                                      "
+  style 0-13 fg=bright-black
+19| <blank>
+20| "You                                                                                                 "
+  style 0-2 fg=bright-blue bold underline
+21| "Reply with exactly the word: TWO. No tools.                                                         "
 22| <blank>
 23| "Assistant                                                                                           "
   style 0-8 fg=bright-magenta bold underline

packages/client/ui-plan/src/client/PlanModeControl.tsx

@@ -37,7 +37,7 @@ export function PlanChip({ useProjection, locked, exitPlanMode }: PlanChipProps)
   if (!target) return null
 
   const off = (): void => {
-    if (leaving || locked) return
+    // No leaving/locked guard: both disable the button, so no click arrives.
     setLeaving(true)
     setError(null)
     void exitPlanMode().then((failure) => {

packages/plan/plan-mode/tests/plan-mode.spec.ts

@@ -607,6 +607,20 @@ describe('/plan', () => {
     expect(ctx.planMode.get(active)).toEqual({ active: false })
   })
 
+  it('idle sessions get the immediate-commit copy on both /plan and /plan off', async () => {
+    const ctx = await setup()
+    await ctx.plugin(CommandService)
+    await new Promise(resolve => setImmediate(resolve))
+    const signal = new AbortController().signal
+    const agent = await agentWithSession(ctx, 'idle-plan-command', { status: 'idle' })
+    expect((await ctx.commands.execute(agent, '/plan', signal))?.result)
+      .toEqual({ kind: 'success', text: 'Plan mode on. Use /plan off to leave.' })
+    expect(foldPlanMode(agent.session.events)).toBe(true)
+    expect((await ctx.commands.execute(agent, '/plan off', signal))?.result)
+      .toEqual({ kind: 'success', text: 'Plan mode off.' })
+    expect(foldPlanMode(agent.session.events)).toBe(false)
+  })
+
   it('removes the contributed command when the plan-mode plugin is disposed', async () => {
     const ctx = new Context()
     await ctx.plugin(SystemPrompt)