tui: clear stale hook row after turn completion (#27619)

Fixes #27210.

## Why
When the app server reports a visible `HookStarted` event for a
`PostToolUse` hook but the turn reaches `TurnCompleted` before a
matching hook completion event arrives, the TUI can leave the transient
`Running PostToolUse hook` row visible after the agent is done.
Interrupted and failed turn cleanup already drops transient live hook
rows; the normal completion path did not.

## What Changed
- Added `ChatWidget::clear_active_hook_cell()` for dropping transient
live hook status without writing it to history.
- Call that cleanup from normal task completion, while reusing it for
the existing start/finalize cleanup paths.
- Added `completed_turn_clears_visible_running_hook` snapshot coverage
for the reported `PostToolUse` case.

## Tests
- `just test -p codex-tui completed_turn_clears_visible_running_hook`
- `just test -p codex-tui` (fails on current `main` in unrelated
guardian tests:
`update_feature_flags_disabling_guardian_clears_review_policy_and_restores_default`
and
`update_feature_flags_disabling_guardian_clears_manual_review_policy_without_history`)

codex-rs/tui/src/chatwidget/hook_lifecycle.rs

@@ -6,6 +6,13 @@
 use super::*;
 
 impl ChatWidget {
+    /// Drop transient live hook status without flushing it into history.
+    pub(super) fn clear_active_hook_cell(&mut self) {
+        if self.active_hook_cell.take().is_some() {
+            self.bump_active_cell_revision();
+        }
+    }
+
     pub(super) fn on_hook_started(&mut self, run: codex_app_server_protocol::HookRunSummary) {
         self.record_visible_turn_activity();
         self.flush_answer_stream_with_separator();

codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__completed_turn_clears_visible_running_hook.snap

@@ -0,0 +1,8 @@
+---
+source: tui/src/chatwidget/tests/status_and_layout.rs
+expression: "format!(\"before completion:\\n{before_completion}after completion:\\n{}\",\nactive_hook_blob(&chat))"
+---
+before completion:
+• Running PostToolUse hook
+after completion:
+<empty>

codex-rs/tui/src/chatwidget/tests/status_and_layout.rs

@@ -2173,6 +2173,32 @@ async fn interrupted_turn_clears_visible_running_hook() {
     );
 }
 
+#[tokio::test]
+async fn completed_turn_clears_visible_running_hook() {
+    let (mut chat, _rx, _op_rx) = make_chatwidget_manual(/*model_override*/ None).await;
+
+    handle_hook_started(
+        &mut chat,
+        hook_started_run(
+            "post-tool-use:0:/tmp/hooks.json",
+            codex_app_server_protocol::HookEventName::PostToolUse,
+            /*status_message*/ None,
+        ),
+    );
+    reveal_running_hooks(&mut chat);
+    let before_completion = active_hook_blob(&chat);
+
+    handle_turn_completed(&mut chat, "turn-1", /*duration_ms*/ None);
+
+    assert_chatwidget_snapshot!(
+        "completed_turn_clears_visible_running_hook",
+        format!(
+            "before completion:\n{before_completion}after completion:\n{}",
+            active_hook_blob(&chat)
+        )
+    );
+}
+
 #[tokio::test]
 async fn status_line_fast_mode_renders_on_and_off() {
     let (mut chat, _rx, _op_rx) = make_chatwidget_manual(/*model_override*/ None).await;

codex-rs/tui/src/chatwidget/turn_runtime.rs

@@ -59,9 +59,7 @@ impl ChatWidget {
         self.quit_shortcut_key = None;
         self.update_task_running_state();
         self.status_state.retry_status_header = None;
-        if self.active_hook_cell.take().is_some() {
-            self.bump_active_cell_revision();
-        }
+        self.clear_active_hook_cell();
         self.status_state.pending_status_indicator_restore = false;
         self.bottom_pane
             .set_interrupt_hint_visible(/*visible*/ true);
@@ -162,6 +160,7 @@ impl ChatWidget {
         // Mark task stopped and request redraw now that all content is in history.
         self.status_state.pending_status_indicator_restore = false;
         self.input_queue.user_turn_pending_start = false;
+        self.clear_active_hook_cell();
         self.turn_lifecycle.finish();
         self.update_task_running_state();
         self.running_commands.clear();
@@ -302,9 +301,7 @@ impl ChatWidget {
         // Turn-scoped hook rows are transient live state; once the turn is over,
         // do not leave an orphaned running row behind if no matching completion
         // event arrived before cancellation.
-        if self.active_hook_cell.take().is_some() {
-            self.bump_active_cell_revision();
-        }
+        self.clear_active_hook_cell();
         // Reset running state and clear streaming buffers.
         self.input_queue.user_turn_pending_start = false;
         self.turn_lifecycle.finish();