feat: journal dashboard widgets, agent polish, and edit-mode live previews

Journal dashboard widgets and quick-add; rich-text quick-add dialogs.

Dashboard draft sync for live edit previews; assistant bubble + API tools.

Journal UX: stress slider, mood grid, query cap fix.

src/modules/agent/assistant-chat-storage.ts

@@ -0,0 +1,54 @@
+export type AssistantChatMessage = {
+  role: "user" | "assistant";
+  content: string;
+};
+
+const STORAGE_VERSION = "v1";
+const MAX_MESSAGES = 40;
+
+function storageKey(userId: string) {
+  return `assistant-chat:${STORAGE_VERSION}:${userId}`;
+}
+
+function isValidMessage(value: unknown): value is AssistantChatMessage {
+  if (!value || typeof value !== "object") return false;
+  const row = value as Record<string, unknown>;
+  return (
+    (row.role === "user" || row.role === "assistant") &&
+    typeof row.content === "string" &&
+    row.content.trim().length > 0
+  );
+}
+
+export function loadAssistantChat(userId: string): AssistantChatMessage[] {
+  try {
+    const raw = localStorage.getItem(storageKey(userId));
+    if (!raw) return [];
+    const parsed: unknown = JSON.parse(raw);
+    if (!Array.isArray(parsed)) return [];
+    return parsed.filter(isValidMessage).slice(-MAX_MESSAGES);
+  } catch {
+    return [];
+  }
+}
+
+export function saveAssistantChat(userId: string, messages: AssistantChatMessage[]): void {
+  try {
+    const trimmed = messages.slice(-MAX_MESSAGES);
+    if (trimmed.length === 0) {
+      localStorage.removeItem(storageKey(userId));
+      return;
+    }
+    localStorage.setItem(storageKey(userId), JSON.stringify(trimmed));
+  } catch {
+    // Private browsing, quota exceeded, or disabled storage.
+  }
+}
+
+export function clearAssistantChat(userId: string): void {
+  try {
+    localStorage.removeItem(storageKey(userId));
+  } catch {
+    // Ignore storage errors.
+  }
+}