TUI: skip goal replace prompt for completed goals (#23792)

## Why
Users reported that the replacement confirmation feels unnecessary when
the current thread goal is already complete. In that state, `/goal
<objective>` is starting fresh rather than interrupting active work.

## What changed
`/goal <objective>` now skips the replace confirmation when the existing
goal has `complete` status and uses the existing fresh replacement path.
Goals that are active, paused, blocked, usage-limited, or budget-limited
still require confirmation before being replaced.

codex-rs/tui/src/app/thread_goal_actions.rs

@@ -8,6 +8,7 @@ use crate::bottom_pane::SelectionViewParams;
 use crate::bottom_pane::popup_consts::standard_popup_hint_line;
 use crate::goal_display::goal_status_label;
 use crate::goal_display::goal_usage_summary;
+use codex_app_server_protocol::ThreadGoal;
 use codex_app_server_protocol::ThreadGoalStatus;
 use codex_protocol::ThreadId;
 
@@ -116,25 +117,30 @@ impl App {
         objective: String,
         mode: ThreadGoalSetMode,
     ) {
-        if matches!(mode, ThreadGoalSetMode::ConfirmIfExists) {
+        let mode = if matches!(mode, ThreadGoalSetMode::ConfirmIfExists) {
             let result = app_server.thread_goal_get(thread_id).await;
             if self.current_displayed_thread_id() != Some(thread_id) {
                 return;
             }
 
             match result {
-                Ok(response) if response.goal.is_some() => {
-                    self.show_replace_thread_goal_confirmation(thread_id, objective);
-                    return;
-                }
-                Ok(_) => {}
+                Ok(response) => match response.goal.as_ref() {
+                    Some(goal) if should_confirm_before_replacing_goal(goal) => {
+                        self.show_replace_thread_goal_confirmation(thread_id, objective);
+                        return;
+                    }
+                    Some(_) => ThreadGoalSetMode::ReplaceExisting,
+                    None => mode,
+                },
                 Err(err) => {
                     self.chat_widget
                         .add_error_message(thread_goal_error_message("read", &err));
                     return;
                 }
             }
-        }
+        } else {
+            mode
+        };
 
         let replacing_goal = matches!(mode, ThreadGoalSetMode::ReplaceExisting);
         if replacing_goal {
@@ -296,6 +302,19 @@ fn is_ephemeral_thread_goal_error(err: &color_eyre::Report) -> bool {
     })
 }
 
+fn should_confirm_before_replacing_goal(goal: &ThreadGoal) -> bool {
+    // Completed goals are terminal, so `/goal <objective>` can start a fresh goal
+    // without asking the user to confirm replacing already-finished work.
+    match goal.status {
+        ThreadGoalStatus::Complete => false,
+        ThreadGoalStatus::Active
+        | ThreadGoalStatus::Paused
+        | ThreadGoalStatus::Blocked
+        | ThreadGoalStatus::UsageLimited
+        | ThreadGoalStatus::BudgetLimited => true,
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use crate::history_cell::HistoryCell;
@@ -350,4 +369,37 @@ mod tests {
             "Failed to read thread goal: thread/goal/get failed in TUI"
         );
     }
+
+    #[test]
+    fn completed_goal_does_not_require_replace_confirmation() {
+        assert!(!should_confirm_before_replacing_goal(&test_goal(
+            ThreadGoalStatus::Complete
+        )));
+    }
+
+    #[test]
+    fn unfinished_goals_require_replace_confirmation() {
+        for status in [
+            ThreadGoalStatus::Active,
+            ThreadGoalStatus::Paused,
+            ThreadGoalStatus::Blocked,
+            ThreadGoalStatus::UsageLimited,
+            ThreadGoalStatus::BudgetLimited,
+        ] {
+            assert!(should_confirm_before_replacing_goal(&test_goal(status)));
+        }
+    }
+
+    fn test_goal(status: ThreadGoalStatus) -> ThreadGoal {
+        ThreadGoal {
+            thread_id: ThreadId::new().to_string(),
+            objective: "Finish the thing.".to_string(),
+            status,
+            token_budget: None,
+            tokens_used: 0,
+            time_used_seconds: 0,
+            created_at: 1_776_272_400,
+            updated_at: 1_776_272_460,
+        }
+    }
 }