Auto-clear completed todo trees

tests/prompt.test.ts

@@ -42,6 +42,56 @@ test("registers the conflict-free /todo command", async () => {
   assert.deepEqual(notifications, ["No todos yet."]);
 });
 
+test("persists automatic clears before deletion, retries failures, and cancels on shutdown", async (context) => {
+  context.mock.timers.enable({ apis: ["setTimeout"] });
+  context.mock.method(console, "error", () => {});
+  const handlers = new Map<string, (event: any, ctx: any) => unknown>();
+  const tools = new Map<string, any>();
+  const entries: Array<{ customType: string; data: unknown }> = [];
+  let persistAttempts = 0;
+  const pi = {
+    on(name: string, handler: (event: any, ctx: any) => unknown) {
+      handlers.set(name, handler);
+    },
+    registerTool(tool: any) {
+      tools.set(tool.name, tool);
+    },
+    registerCommand() {},
+    appendEntry(customType: string, data: unknown) {
+      persistAttempts += 1;
+      if (persistAttempts === 1) throw new Error("disk unavailable");
+      entries.push({ customType, data });
+    },
+  };
+  const ctx = { ui: { setWidget() {} } };
+  piTodoHerdr(pi as never);
+
+  await tools.get("set_tasks").execute(
+    "set",
+    { mode: "append", tasks: [{ name: "Done", status: "done" }], force: false },
+    undefined,
+    undefined,
+    ctx,
+  );
+  context.mock.timers.tick(10_000);
+  assert.equal((await tools.get("list_task").execute()).content[0].text, "1 [done] Done");
+
+  context.mock.timers.tick(10_000);
+  assert.equal((await tools.get("list_task").execute()).content[0].text, "No tasks.");
+  assert.deepEqual(entries, [{ customType: "pi-todo-herdr-state", data: { tasks: [], nextId: 1 } }]);
+
+  await tools.get("set_tasks").execute(
+    "set",
+    { mode: "append", tasks: [{ name: "Done again", status: "done" }], force: false },
+    undefined,
+    undefined,
+    ctx,
+  );
+  await handlers.get("session_shutdown")?.({ reason: "reload" }, ctx);
+  context.mock.timers.tick(10_000);
+  assert.equal((await tools.get("list_task").execute()).content[0].text, "1 [done] Done again");
+});
+
 test("keeps task guidance short with planning after exploration", () => {
   assert.equal(TASK_PROMPT_GUIDELINES.length, 2);
   const prompt = TASK_PROMPT_GUIDELINES.join("\n");