fix(dsh-plugin): re-arm lazy tools from history after a plugin reload

packages/dsh-plugin-browserskill/src/lazy-tools.ts

@@ -133,8 +133,23 @@ export function armLazyTools(ctx: Context, registerSuite: () => () => void): ()
 
   // Live gesture/append feed: covers /browser-skill user gestures (no tool
   // call happens on that path) landing as skill-invocation messages.
-  const onSessionEvent = (_session: SessionLike, event: SessionEventLike): void => {
-    if (isSkillInvocationMessage(event?.data)) ensureSuite();
+  const onSessionEvent = (session: SessionLike, event: SessionEventLike): void => {
+    if (suiteDisposer !== undefined) return;
+    if (isSkillInvocationMessage(event?.data)) {
+      ensureSuite();
+      return;
+    }
+    // Reload recovery. The history scan below runs once, when the plugin is
+    // applied, and it covers neither of the reload cases: a session that
+    // already exists never emits `session/created`, and `ctx.get("sessions")`
+    // yields nothing when the sessions service is registered after this
+    // plugin. The suite then stays hidden until the model happens to invoke
+    // the skill again, which surfaces as `unknown tool "browser_session"`.
+    //
+    // The session is already in hand on every event, so let any later event
+    // re-derive the reveal from durable history. Guarded above, so this scans
+    // only while still hidden.
+    if (session !== undefined && session !== null) scanSession(session);
   };
   disposers.push(ctx.on("session/event" as never, onSessionEvent as never));
 

packages/dsh-plugin-browserskill/tests/lazy-tools.test.ts

@@ -135,6 +135,65 @@ describe("armLazyTools", () => {
     expect(missRegister).not.toHaveBeenCalled();
   });
 
+  it("re-arms from history on a later event when the boot scan could not see the session", () => {
+    const hitEvents = [
+      {
+        type: "tool/call",
+        data: { callId: "c1", name: "skill", arguments: '{"name":"browser-skill"}' },
+      },
+      { type: "tool/result", data: { message: { callId: "c1", isError: false } } },
+    ];
+    // After a plugin reload the sessions service may not be registered yet, so
+    // ctx.get("sessions") yields nothing and the boot scan covers nothing; the
+    // session already exists, so session/created never fires for it either.
+    const { ctx, listeners } = fakeEventCtx();
+    const registerSuite = vi.fn(() => () => {});
+    armLazyTools(ctx, registerSuite);
+    expect(registerSuite).not.toHaveBeenCalled();
+
+    // An ordinary event carrying no invocation of its own still hands over the
+    // session, whose durable history proves the skill already ran.
+    callListeners(listeners, "session/event", { events: hitEvents }, { type: "message/append" });
+    expect(registerSuite).toHaveBeenCalledTimes(1);
+  });
+
+  it("does not reveal from an event whose session has no proof", () => {
+    const { ctx, listeners } = fakeEventCtx();
+    const registerSuite = vi.fn(() => () => {});
+    armLazyTools(ctx, registerSuite);
+    callListeners(
+      listeners,
+      "session/event",
+      { events: [{ type: "message/append", data: {} }] },
+      { type: "message/append" },
+    );
+    expect(registerSuite).not.toHaveBeenCalled();
+  });
+
+  it("stops scanning session history once the suite is revealed", () => {
+    const { ctx, listeners } = fakeEventCtx();
+    const registerSuite = vi.fn(() => () => {});
+    armLazyTools(ctx, registerSuite);
+    callListeners(
+      listeners,
+      "tools/result",
+      { name: "skill", arguments: { name: "browser-skill" } },
+      { isError: false },
+    );
+    expect(registerSuite).toHaveBeenCalledTimes(1);
+
+    // Events arrive constantly; re-deriving from history on each one after the
+    // reveal would be pure waste. A session that would throw if read proves
+    // the history is not touched again.
+    const exploding = {
+      get events(): never {
+        throw new Error("session history must not be read after the reveal");
+      },
+    };
+    callListeners(listeners, "session/event", exploding, { type: "message/append" });
+    expect(registerSuite).toHaveBeenCalledTimes(1);
+  });
+
   it("disposes listeners and the revealed suite", () => {
     const { ctx, listeners } = fakeEventCtx();
     const suiteDispose = vi.fn();