feat(composer): persist text + reply target per chat across restarts

apps/desktop/src/lib/composerDraftStore.ts

@@ -0,0 +1,160 @@
+// Composer-draft persistence. Two-tier semantics:
+//   * In-memory `Map<convId, Draft>` for instant synchronous reads on
+//     mount (mirrors the `messageMemoryCache` pattern from Phase 7).
+//   * SQLite (`composer_drafts` table, schema in `messageCache.ts`) for
+//     cross-restart persistence. Writes are debounced and fire-and-forget
+//     — losing the last 400ms of typing on a hard crash is acceptable;
+//     blocking the keystroke handler is not.
+//
+// Attachments are intentionally NOT serialized:
+//   * Files don't round-trip through SQLite cleanly (binary blobs blow
+//     up the cache size).
+//   * `replyToId` IS persisted; the consuming page looks up the actual
+//     message by id at render time.
+
+import { isTauriRuntime } from './globalShortcut';
+
+const DB_NAME = 'chatapp-cache';
+const WRITE_DEBOUNCE_MS = 400;
+
+interface Draft {
+  text: string;
+  replyToId: string | null;
+}
+
+interface DraftRow {
+  conversation_id: string;
+  text: string;
+  reply_to_id: string | null;
+  updated_at: string;
+}
+
+const drafts = new Map<string, Draft>();
+const pendingWrites = new Map<string, ReturnType<typeof setTimeout>>();
+let handlePromise: Promise<string | null> | null = null;
+
+async function getHandle(): Promise<string | null> {
+  if (handlePromise) return handlePromise;
+  if (!isTauriRuntime()) {
+    handlePromise = Promise.resolve(null);
+    return handlePromise;
+  }
+  handlePromise = (async () => {
+    try {
+      const handle = await window.electronAPI.sqlLoad({ name: DB_NAME });
+      // Self-contained DDL — the same statement also runs from
+      // `messageCache.ts`'s init path, but we don't want to depend on
+      // call order. SQLite's `CREATE TABLE IF NOT EXISTS` is idempotent
+      // so the double-creation is safe.
+      await window.electronAPI.sqlExecute({
+        handle,
+        query:
+          `CREATE TABLE IF NOT EXISTS composer_drafts (
+             conversation_id TEXT PRIMARY KEY,
+             text TEXT NOT NULL,
+             reply_to_id TEXT,
+             updated_at TEXT NOT NULL
+           )`,
+        bindings: [],
+      });
+      return handle;
+    } catch (err: unknown) {
+      console.warn('composerDraftStore: sqlLoad failed', err);
+      return null;
+    }
+  })();
+  return handlePromise;
+}
+
+export function getDraftSync(conversationId: string): Draft | null {
+  const stored = drafts.get(conversationId);
+  if (!stored) return null;
+  return { text: stored.text, replyToId: stored.replyToId };
+}
+
+export function hasDraft(conversationId: string): boolean {
+  return drafts.has(conversationId);
+}
+
+export function setDraft(conversationId: string, draft: Draft): void {
+  if (draft.text.length === 0 && draft.replyToId === null) {
+    if (drafts.has(conversationId)) {
+      drafts.delete(conversationId);
+      scheduleWrite(conversationId);
+    }
+    return;
+  }
+  drafts.set(conversationId, { text: draft.text, replyToId: draft.replyToId });
+  scheduleWrite(conversationId);
+}
+
+export function clearDraft(conversationId: string): void {
+  if (!drafts.has(conversationId)) return;
+  drafts.delete(conversationId);
+  scheduleWrite(conversationId);
+}
+
+function scheduleWrite(conversationId: string): void {
+  const existing = pendingWrites.get(conversationId);
+  if (existing) clearTimeout(existing);
+  const timer = setTimeout(() => {
+    pendingWrites.delete(conversationId);
+    void flushOne(conversationId);
+  }, WRITE_DEBOUNCE_MS);
+  pendingWrites.set(conversationId, timer);
+}
+
+async function flushOne(conversationId: string): Promise<void> {
+  const handle = await getHandle();
+  if (!handle) return;
+  const draft = drafts.get(conversationId);
+  try {
+    if (draft) {
+      await window.electronAPI.sqlExecute({
+        handle,
+        query:
+          `INSERT INTO composer_drafts (conversation_id, text, reply_to_id, updated_at)
+           VALUES ($1, $2, $3, $4)
+           ON CONFLICT(conversation_id) DO UPDATE SET
+             text = excluded.text,
+             reply_to_id = excluded.reply_to_id,
+             updated_at = excluded.updated_at`,
+        bindings: [conversationId, draft.text, draft.replyToId, new Date().toISOString()],
+      });
+    } else {
+      await window.electronAPI.sqlExecute({
+        handle,
+        query: 'DELETE FROM composer_drafts WHERE conversation_id = $1',
+        bindings: [conversationId],
+      });
+    }
+  } catch (err: unknown) {
+    console.warn('composerDraftStore: flush failed', err);
+  }
+}
+
+export async function hydrateDrafts(): Promise<void> {
+  const handle = await getHandle();
+  if (!handle) return;
+  try {
+    const rows = (await window.electronAPI.sqlSelect({
+      handle,
+      query: 'SELECT conversation_id, text, reply_to_id, updated_at FROM composer_drafts',
+      bindings: [],
+    })) as unknown as DraftRow[];
+    for (const r of rows) {
+      if (!r.conversation_id || typeof r.text !== 'string') continue;
+      if (r.text.length === 0 && r.reply_to_id === null) continue;
+      drafts.set(r.conversation_id, { text: r.text, replyToId: r.reply_to_id });
+    }
+  } catch (err: unknown) {
+    console.warn('composerDraftStore: hydrate failed', err);
+  }
+}
+
+export function __resetForTests(): void {
+  for (const t of pendingWrites.values()) clearTimeout(t);
+  pendingWrites.clear();
+  drafts.clear();
+  handlePromise = null;
+}