fix(tui): refresh the context bar when auto-compaction starts

AutoCompactStarted carries the count the trigger fired on, but only
AutoCompactCompleted refreshed the context bar, so the "N% full" banner
sat next to a stale pre-turn number until the next stream update. Both
lifecycle updates now refresh the bar, on the root view and on subagent
views.

Ported from upstream 1.0.12 (grok-build acp_handler/session_notification.rs).

Claude-Session: https://claude.ai/code/session_01RUqV8HVGXcAETyYbZ2tPQ4

crates/codegen/kigi-tui/src/app/acp_handler/session_notification.rs

@@ -45,6 +45,14 @@ pub(super) fn refresh_context_used(view: &mut AgentView, used: u64) {
     let total = view.session.models.get_context_window().unwrap_or(0);
     view.apply_context_used(used, total);
 }
+/// The count a compaction lifecycle update carries for the context bar: the banner's "N% full" must not sit next to a stale pre-turn number.
+pub(super) fn compaction_context_refresh(update: &XaiSessionUpdate) -> Option<u64> {
+    match update {
+        XaiSessionUpdate::AutoCompactStarted { tokens_used, .. } => Some(*tokens_used),
+        XaiSessionUpdate::AutoCompactCompleted { tokens_after, .. } => Some(*tokens_after),
+        _ => None,
+    }
+}
 /// Refresh the bar and record `used` as the confirmed count for a pending
 /// compaction message; call only from the `meta.totalTokens` path.
 pub(super) fn confirm_context_used(view: &mut AgentView, used: u64) {
@@ -197,8 +205,10 @@ pub(super) fn handle_session_notification(notif: &acp::ExtNotification, app: &mu
                 &mut agent.scrollback,
                 is_api_key_auth,
             );
-            if let XaiSessionUpdate::AutoCompactCompleted { tokens_after, .. } = update {
-                refresh_context_used(agent, *tokens_after);
+            if let Some(used) = compaction_context_refresh(update) {
+                refresh_context_used(agent, used);
+            }
+            if let XaiSessionUpdate::AutoCompactCompleted { .. } = update {
                 agent.todo.update_todos(Vec::new());
             }
             changed
@@ -1071,10 +1081,7 @@ pub(super) fn handle_child_session_notification(
         | XaiSessionUpdate::AutoCompactFailed { .. }
         | XaiSessionUpdate::AutoCompactCancelled { .. }
         | XaiSessionUpdate::RetryState(_) => {
-            let compact_tokens = match &update {
-                XaiSessionUpdate::AutoCompactCompleted { tokens_after, .. } => Some(*tokens_after),
-                _ => None,
-            };
+            let compact_tokens = compaction_context_refresh(&update);
             let mut changed = false;
             if let Some(child_view) = agent.subagent_views.get_mut(child_sid) {
                 changed = apply_session_event(

crates/codegen/kigi-tui/src/app/acp_handler/tests/session_events.rs

@@ -576,9 +576,8 @@
     }
 
     #[test]
-    fn child_compact_started_does_not_reset_context_used() {
-        // Sibling variants in the same outer arm must not touch the numerator;
-        // guards against accidental widening of the AutoCompactCompleted gate.
+    fn child_compact_started_refreshes_context_used() {
+        // AutoCompactStarted carries the count the trigger fired on; the child bar must show it.
         let mut agent = make_agent(Some("root-sess"));
         let child_sid = "child-sess-3";
         agent
@@ -603,7 +602,17 @@
         let child_view = agent.subagent_views.get(child_sid).unwrap();
         assert_eq!(
             child_view.context_state.as_ref().map(|c| c.used),
-            Some(90_000)
+            Some(95_000)
+        );
+        // A sibling variant without a count leaves the numerator alone.
+        let cancelled = XaiSessionUpdate::AutoCompactCancelled {
+            reason: "user".into(),
+        };
+        let _ = handle_child_session_notification(cancelled, child_sid, &mut agent, false);
+        let child_view = agent.subagent_views.get(child_sid).unwrap();
+        assert_eq!(
+            child_view.context_state.as_ref().map(|c| c.used),
+            Some(95_000)
         );
     }
 
@@ -693,5 +702,30 @@
             !session.model_incompatible,
             "non-encrypted_content error types must not set model_incompatible"
         );
+
     }
 
+    /// The banner's count must also refresh the context bar.
+    #[test]
+    fn auto_compact_started_refreshes_the_context_bar() {
+        let mut app = make_app_with_agent("sess-1");
+        let id = AgentId(0);
+        app.agents.get_mut(&id).unwrap().apply_context_used(15_000, 262_144);
+        let payload = SessionNotification {
+            session_id: acp::SessionId::new("sess-1"),
+            update: XaiSessionUpdate::AutoCompactStarted {
+                tokens_used: 90_000,
+                context_window: 262_144,
+                percentage: 34,
+                reason: "threshold".into(),
+            },
+            meta: None,
+        };
+        let notif = acp::ExtNotification::new(
+            "kigi/session/update",
+            std::sync::Arc::from(serde_json::value::to_raw_value(&payload).unwrap()),
+        );
+        let _ = handle_ext_notification(&notif, &mut app);
+        let bar = app.agents[&id].context_state.as_ref().map(|c| (c.used, c.total));
+        assert_eq!(bar, Some((90_000, 262_144)));
+    }