feat: add local SQLite memory store

src/sqlite-memory-store.ts

@@ -0,0 +1,62 @@
+import { type MemoryRecord, recallMemories } from './db.js';
+
+const DEFAULT_PAGE_SIZE = 6;
+const DEFAULT_MAX_BRIEFING_CHARS = 2_000;
+
+function trimToMaxChars(text: string, maxChars: number): string {
+  if (text.length <= maxChars) return text;
+  return text.slice(0, Math.max(0, maxChars - 1)).trimEnd() + '…';
+}
+
+export function buildRoomMemoryKey(groupFolder: string): string {
+  return `room:${groupFolder}`;
+}
+
+export function formatRoomMemoryBriefing(
+  roomKey: string,
+  memories: MemoryRecord[],
+  maxChars = DEFAULT_MAX_BRIEFING_CHARS,
+): string | undefined {
+  if (memories.length === 0) return undefined;
+
+  const lines = memories
+    .map((memory) => {
+      const content = memory.content.trim();
+      if (!content) return null;
+      const prefix = memory.memoryKind ? `- [${memory.memoryKind}] ` : '- ';
+      return `${prefix}${content}`;
+    })
+    .filter((line): line is string => Boolean(line));
+
+  if (lines.length === 0) return undefined;
+
+  const text = [
+    '## Shared Room Memory',
+    `Room key: \`${roomKey}\``,
+    'Treat this as background context for a fresh session start. The current conversation always takes precedence.',
+    ...lines,
+  ].join('\n');
+
+  return trimToMaxChars(text, maxChars);
+}
+
+export async function buildRoomMemoryBriefing(args: {
+  groupFolder: string;
+  groupName?: string;
+  maxChars?: number;
+  limit?: number;
+}): Promise<string | undefined> {
+  void args.groupName;
+  const roomKey = buildRoomMemoryKey(args.groupFolder);
+  const memories = recallMemories({
+    scopeKind: 'room',
+    scopeKey: roomKey,
+    limit: args.limit ?? DEFAULT_PAGE_SIZE,
+  });
+
+  return formatRoomMemoryBriefing(
+    roomKey,
+    memories,
+    args.maxChars ?? DEFAULT_MAX_BRIEFING_CHARS,
+  );
+}