feat(tui): show context used in plan implementation prompt

codex-rs/tui/src/chatwidget.rs

@@ -2480,17 +2480,48 @@ impl ChatWidget {
 
     fn open_plan_implementation_prompt(&mut self) {
         let default_mask = collaboration_modes::default_mode_mask(self.model_catalog.as_ref());
+        let context_usage_label = self.plan_implementation_context_usage_label();
 
         self.bottom_pane
             .show_selection_view(plan_implementation::selection_view_params(
                 default_mask,
                 self.latest_proposed_plan_markdown.as_deref(),
+                context_usage_label.as_deref(),
             ));
         self.notify(Notification::PlanModePrompt {
             title: PLAN_IMPLEMENTATION_TITLE.to_string(),
         });
     }
 
+    /// Returns a context-used label for the plan implementation prompt.
+    ///
+    /// The footer reports context remaining because it is ambient status, but
+    /// this prompt is asking whether to discard prior conversation state before
+    /// implementing a plan. Reporting used context makes the cleanup tradeoff
+    /// explicit. A fully fresh or unknown context window returns no label so
+    /// the clear-context option does not imply urgency without evidence.
+    fn plan_implementation_context_usage_label(&self) -> Option<String> {
+        let info = self.token_info.as_ref()?;
+        let percent = self.context_remaining_percent(info);
+
+        let used_tokens = self.context_used_tokens(info, percent.is_some());
+        if let Some(percent) = percent {
+            let used_percent = 100 - percent.clamp(0, 100);
+            if used_percent <= 0 {
+                return None;
+            }
+            return Some(format!("{used_percent}% used"));
+        }
+
+        if let Some(tokens) = used_tokens
+            && tokens > 0
+        {
+            return Some(format!("{} used", format_tokens_compact(tokens)));
+        }
+
+        None
+    }
+
     fn has_queued_follow_up_messages(&self) -> bool {
         !self.rejected_steers_queue.is_empty() || !self.queued_user_messages.is_empty()
     }

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

@@ -20,9 +20,15 @@ pub(super) const PLAN_IMPLEMENTATION_CLEAR_CONTEXT_PREFIX: &str = concat!(
 pub(super) const PLAN_IMPLEMENTATION_DEFAULT_UNAVAILABLE: &str = "Default mode unavailable";
 pub(super) const PLAN_IMPLEMENTATION_NO_APPROVED_PLAN: &str = "No approved plan available";
 
+/// Builds the confirmation prompt shown after a plan is approved in Plan mode.
+///
+/// The optional usage label is already phrased for display, such as `89% used`
+/// or `123K used`. This module only decides where that label belongs in the
+/// decision copy so action wiring stays separate from token accounting.
 pub(super) fn selection_view_params(
     default_mask: Option<CollaborationModeMask>,
     plan_markdown: Option<&str>,
+    clear_context_usage_label: Option<&str>,
 ) -> SelectionViewParams {
     let (implement_actions, implement_disabled_reason) = match default_mask.clone() {
         Some(mask) => {
@@ -63,6 +69,11 @@ pub(super) fn selection_view_params(
         ),
     };
 
+    let clear_context_description = clear_context_usage_label.map_or_else(
+        || "Fresh thread with this plan.".to_string(),
+        |label| format!("Fresh thread. Context: {label}."),
+    );
+
     SelectionViewParams {
         title: Some(PLAN_IMPLEMENTATION_TITLE.to_string()),
         subtitle: None,
@@ -80,7 +91,7 @@ pub(super) fn selection_view_params(
             },
             SelectionItem {
                 name: PLAN_IMPLEMENTATION_CLEAR_CONTEXT.to_string(),
-                description: Some("Fresh thread with this plan.".to_string()),
+                description: Some(clear_context_description),
                 selected_description: None,
                 is_current: false,
                 actions: clear_context_actions,

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

@@ -0,0 +1,11 @@
+---
+source: tui/src/chatwidget/tests/plan_mode.rs
+expression: popup
+---
+  Implement this plan?
+
+› 1. Yes, implement this plan          Switch to Default and start coding.
+  2. Yes, clear context and implement  Fresh thread. Context: 89% used.
+  3. No, stay in Plan mode             Continue planning with the model.
+
+  Press enter to confirm or esc to go back

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

@@ -11,6 +11,19 @@ async fn plan_implementation_popup_snapshot() {
     assert_chatwidget_snapshot!("plan_implementation_popup", popup);
 }
 
+#[tokio::test]
+async fn plan_implementation_popup_context_usage_snapshot() {
+    let (mut chat, _rx, _op_rx) = make_chatwidget_manual(Some("gpt-5")).await;
+    chat.set_token_info(Some(make_token_info(
+        /*total_tokens*/ 90_000, /*context_window*/ 100_000,
+    )));
+    chat.on_plan_item_completed("- Step 1\n- Step 2\n".to_string());
+    chat.open_plan_implementation_prompt();
+
+    let popup = render_bottom_popup(&chat, /*width*/ 80);
+    assert_chatwidget_snapshot!("plan_implementation_popup_context_usage", popup);
+}
+
 #[tokio::test]
 async fn plan_implementation_popup_no_selected_snapshot() {
     let (mut chat, _rx, _op_rx) = make_chatwidget_manual(Some("gpt-5")).await;
@@ -74,8 +87,11 @@ async fn plan_implementation_clear_context_requires_default_mode_and_plan() {
     let default_mask = collaboration_modes::default_mode_mask(chat.model_catalog.as_ref())
         .expect("expected default collaboration mode");
 
-    let params =
-        plan_implementation::selection_view_params(/*default_mask*/ None, Some("- Step\n"));
+    let params = plan_implementation::selection_view_params(
+        /*default_mask*/ None,
+        Some("- Step\n"),
+        /*clear_context_usage_label*/ None,
+    );
     assert_eq!(
         params.items[1].disabled_reason.as_deref(),
         Some(plan_implementation::PLAN_IMPLEMENTATION_DEFAULT_UNAVAILABLE)
@@ -84,22 +100,45 @@ async fn plan_implementation_clear_context_requires_default_mode_and_plan() {
     let params = plan_implementation::selection_view_params(
         Some(default_mask.clone()),
         /*plan_markdown*/ None,
+        /*clear_context_usage_label*/ None,
     );
     assert_eq!(
         params.items[1].disabled_reason.as_deref(),
         Some(plan_implementation::PLAN_IMPLEMENTATION_NO_APPROVED_PLAN)
     );
 
-    let params =
-        plan_implementation::selection_view_params(Some(default_mask.clone()), Some("  \n"));
+    let params = plan_implementation::selection_view_params(
+        Some(default_mask.clone()),
+        Some("  \n"),
+        /*clear_context_usage_label*/ None,
+    );
     assert_eq!(
         params.items[1].disabled_reason.as_deref(),
         Some(plan_implementation::PLAN_IMPLEMENTATION_NO_APPROVED_PLAN)
     );
 
-    let params = plan_implementation::selection_view_params(Some(default_mask), Some("- Step\n"));
+    let params = plan_implementation::selection_view_params(
+        Some(default_mask.clone()),
+        Some("- Step\n"),
+        /*clear_context_usage_label*/ None,
+    );
     assert_eq!(params.items[1].disabled_reason, None);
     assert!(!params.items[1].actions.is_empty());
+
+    assert_eq!(
+        params.items[1].description.as_deref(),
+        Some("Fresh thread with this plan.")
+    );
+
+    let params = plan_implementation::selection_view_params(
+        Some(default_mask),
+        Some("- Step\n"),
+        Some("89% used"),
+    );
+    assert_eq!(
+        params.items[1].description.as_deref(),
+        Some("Fresh thread. Context: 89% used.")
+    );
 }
 
 #[tokio::test]