Add file-backed durable memory tools

src/memory.ts

@@ -0,0 +1,67 @@
+import { appendFile, mkdir, readFile, writeFile } from "node:fs/promises";
+import { dirname, join, resolve } from "node:path";
+
+export type MemoryFile = "memory" | "user";
+
+export class MemoryStore {
+  private readonly root: string;
+  private readonly dailyDir: string;
+
+  constructor(rootDir: string) {
+    this.root = rootDir;
+    this.dailyDir = join(rootDir, "daily");
+  }
+
+  async ensure(): Promise<void> {
+    await mkdir(this.dailyDir, { recursive: true });
+    await this.ensureFile(this.pathFor("memory"), "# Memory\n\n");
+    await this.ensureFile(this.pathFor("user"), "# User\n\n");
+  }
+
+  async read(file: MemoryFile): Promise<string> {
+    await this.ensure();
+    return await readFile(this.pathFor(file), "utf8");
+  }
+
+  async append(file: MemoryFile, content: string): Promise<void> {
+    await this.ensure();
+    await appendFile(this.pathFor(file), `${content.trim()}\n\n`, "utf8");
+  }
+
+  async appendDaily(content: string, date = new Date()): Promise<string> {
+    await this.ensure();
+    const filePath = this.dailyPath(date);
+    await this.ensureFile(filePath, `# ${this.dayStamp(date)}\n\n`);
+    await appendFile(filePath, `${content.trim()}\n\n`, "utf8");
+    return resolve(filePath);
+  }
+
+  getSummaryPaths(): { memory: string; user: string; dailyDir: string } {
+    return {
+      memory: resolve(this.pathFor("memory")),
+      user: resolve(this.pathFor("user")),
+      dailyDir: resolve(this.dailyDir)
+    };
+  }
+
+  private pathFor(file: MemoryFile): string {
+    return join(this.root, file === "memory" ? "MEMORY.md" : "USER.md");
+  }
+
+  private dailyPath(date: Date): string {
+    return join(this.dailyDir, `${this.dayStamp(date)}.md`);
+  }
+
+  private dayStamp(date: Date): string {
+    return date.toISOString().slice(0, 10);
+  }
+
+  private async ensureFile(filePath: string, initialContent: string): Promise<void> {
+    await mkdir(dirname(filePath), { recursive: true });
+    try {
+      await readFile(filePath, "utf8");
+    } catch {
+      await writeFile(filePath, initialContent, "utf8");
+    }
+  }
+}