fix: PlanApprovalAlert bugs + plan mode race condition

- Fix double-fire: handleApprove() now only calls approvePlan(), no longer also sends postMessage
- Fix modify: handleModify() now calls modifyPlan() from store (opens PLAN.md in editor)
- Remove unused postMessage prop from PlanApprovalAlert interface and BaseChat
- Fix race condition: reset chatId/description/chatMetadata atoms on home page navigation
  so wasNewChat detection works correctly for new chats after navigating away

Author: zebbern

app/components/chat/BaseChat.tsx

@@ -470,11 +470,7 @@ export const BaseChat = React.forwardRef<HTMLDivElement, BaseChatProps>(
                     )}
                     {llmErrorAlert && <LlmErrorAlert alert={llmErrorAlert} clearAlert={() => clearLlmErrorAlert?.()} />}
                     {/* Plan Approval Alert - shows when a plan is pending approval */}
-                    <PlanApprovalAlert
-                      postMessage={(message) => {
-                        sendMessage?.(undefined, message);
-                      }}
-                    />
+                    <PlanApprovalAlert />
                   </div>
                   {progressAnnotations && <ProgressCompilation data={progressAnnotations} />}
 

app/components/chat/PlanApprovalAlert.tsx

@@ -1,7 +1,7 @@
 import React, { memo, useCallback } from 'react';
 import { useStore } from '@nanostores/react';
 import { motion, AnimatePresence } from 'framer-motion';
-import { planStore, planProgress, approvePlan, rejectPlan, type PlanTask } from '~/lib/stores/plan';
+import { planStore, planProgress, approvePlan, rejectPlan, modifyPlan, type PlanTask } from '~/lib/stores/plan';
 import { classNames } from '~/utils/classNames';
 import { Button } from '~/components/ui/Button';
 import { Progress } from '~/components/ui/Progress';
@@ -28,35 +28,29 @@ interface PlanApprovalAlertProps {
 
   /** Optional callback when plan is rejected */
   onReject?: () => void;
-
-  /** Optional callback to send a message to continue execution */
-  postMessage?: (message: string) => void;
 }
 
 /**
- * PlanApprovalAlert component - shows in the chat area when a plan is pending approval
+ * PlanApprovalAlert component - shows in the chat area when a plan is pending approval.
+ * Buttons delegate to planActionAtom via store functions; Chat.client.tsx handles the rest.
  */
-export const PlanApprovalAlert = memo(({ onApprove, onReject, postMessage }: PlanApprovalAlertProps) => {
+export const PlanApprovalAlert = memo(({ onApprove, onReject }: PlanApprovalAlertProps) => {
   const state = useStore(planStore);
   const progress = useStore(planProgress);
 
   const handleApprove = useCallback(() => {
-    approvePlan();
+    approvePlan(); // fires planActionAtom('approve') → Chat.client.tsx sends execute message
     onApprove?.();
-
-    // Send a message to continue execution
-    postMessage?.('Plan approved. Please proceed with the implementation.');
-  }, [onApprove, postMessage]);
+  }, [onApprove]);
 
   const handleReject = useCallback(() => {
-    rejectPlan();
+    rejectPlan(); // fires planActionAtom('reject') → Chat.client.tsx shows cancel toast
     onReject?.();
   }, [onReject]);
 
   const handleModify = useCallback(() => {
-    // For now, just reject and ask user to clarify
-    postMessage?.('I would like to modify the plan. Please adjust the following tasks before proceeding...');
-  }, [postMessage]);
+    modifyPlan(); // fires planActionAtom('modify') → Chat.client.tsx opens PLAN.md in editor
+  }, []);
 
   // Don't show if no plan or already approved
   if (!state.isActive || state.tasks.length === 0 || state.approvedByUser) {

app/lib/persistence/useChatHistory.ts

@@ -141,7 +141,16 @@ export function useChatHistory() {
           toast.error('Failed to load chat: ' + error.message); // More specific error
         });
     } else {
-      // Handle case where there is no mixedId (e.g., new chat)
+      /*
+       * Home page (no mixedId) — reset global atoms so stale values from a
+       * previous chat don't leak into a fresh session.  Without this,
+       * chatId retains the old value after navigating back to "/", which
+       * breaks the wasNewChat detection in Chat.client.tsx and causes
+       * plan-mode carry-over to fail for new chats.
+       */
+      chatId.set(undefined);
+      description.set(undefined);
+      chatMetadata.set(undefined);
       setReady(true);
     }
   }, [mixedId, db, navigate, searchParams]); // Added db, navigate, searchParams dependencies