Sync Hermes session titles with the T3 Agent sidebar

CONTEXT.md

@@ -30,6 +30,10 @@ _Avoid_: Project thread, workspace, channel
 The durable Hermes-owned conversation context that the agent continues across turns.
 _Avoid_: T3 transcript, project
 
+**Hermes session title**:
+The Hermes-owned name of a session. A Hermes-backed T3 Agent thread displays this title as a local projection rather than owning an independent name.
+_Avoid_: T3 thread name, synchronized title
+
 **Cross-gateway conversation**:
 A Hermes session that originated from the CLI or another messaging surface rather than T3 Agent.
 _Avoid_: Synced thread

apps/server/src/orchestration/Layers/ProviderCommandReactor.test.ts

@@ -637,6 +637,47 @@ describe("ProviderCommandReactor", () => {
     expect(thread?.title).toBe("Generated title");
   });
 
+  it("leaves the provisional title for Hermes to replace", async () => {
+    const harness = await createHarness({
+      threadModelSelection: {
+        instanceId: ProviderInstanceId.make("hermes"),
+        model: "openai-codex::gpt-5.6-sol",
+      },
+    });
+    const seededTitle = "Please investigate reconnect failures after restar...";
+
+    await Effect.runPromise(
+      harness.engine.dispatch({
+        type: "thread.meta.update",
+        commandId: CommandId.make("cmd-hermes-title-seed"),
+        threadId: ThreadId.make("thread-1"),
+        title: seededTitle,
+      }),
+    );
+    await Effect.runPromise(
+      harness.engine.dispatch({
+        type: "thread.turn.start",
+        commandId: CommandId.make("cmd-hermes-first-turn"),
+        threadId: ThreadId.make("thread-1"),
+        message: {
+          messageId: asMessageId("user-message-hermes-title"),
+          role: "user",
+          text: "Please investigate reconnect failures after restarting the session.",
+          attachments: [],
+        },
+        titleSeed: seededTitle,
+        interactionMode: DEFAULT_PROVIDER_INTERACTION_MODE,
+        runtimeMode: "approval-required",
+        createdAt: "2026-01-01T00:00:00.000Z",
+      }),
+    );
+
+    await waitFor(() => harness.sendTurn.mock.calls.length === 1);
+    expect(harness.generateThreadTitle).not.toHaveBeenCalled();
+    const readModel = await harness.readModel();
+    expect(readModel.threads.find((entry) => entry.id === "thread-1")?.title).toBe(seededTitle);
+  });
+
   it("does not overwrite an existing custom thread title on the first turn", async () => {
     const harness = await createHarness();
     const now = "2026-01-01T00:00:00.000Z";

apps/server/src/orchestration/Layers/ProviderCommandReactor.ts

@@ -7,6 +7,7 @@ import {
   ProviderDriverKind,
   type ProjectId,
   type OrchestrationSession,
+  ProviderInstanceId,
   ThreadId,
   type ProviderSession,
   type RuntimeMode,
@@ -87,6 +88,7 @@ const HANDLED_TURN_START_KEY_MAX = 10_000;
 const HANDLED_TURN_START_KEY_TTL = Duration.minutes(30);
 const DEFAULT_RUNTIME_MODE: RuntimeMode = "full-access";
 const DEFAULT_THREAD_TITLE = "New thread";
+const HERMES_PROVIDER_INSTANCE_ID = ProviderInstanceId.make("hermes");
 
 export function providerErrorLabel(value: string | undefined): string {
   const normalized = value?.trim();
@@ -816,7 +818,10 @@ const make = Effect.gen(function* () {
         ...generationInput,
       }).pipe(Effect.forkScoped);
 
-      if (canReplaceThreadTitle(thread.title, event.payload.titleSeed)) {
+      if (
+        thread.modelSelection.instanceId !== HERMES_PROVIDER_INSTANCE_ID &&
+        canReplaceThreadTitle(thread.title, event.payload.titleSeed)
+      ) {
         yield* maybeGenerateThreadTitleForFirstTurn({
           threadId: event.payload.threadId,
           cwd: generationCwd,

apps/server/src/provider/Layers/HermesAdapter.test.ts

@@ -71,6 +71,7 @@ const testLayer = Layer.effect(
       listSessions: Effect.die("not used by adapter tests"),
       forkSession: () => Effect.die("not used by adapter tests"),
       deleteSession: () => Effect.die("not used by adapter tests"),
+      updateSessionTitle: () => Effect.die("not used by adapter tests"),
     };
     const adapter = yield* makeHermesAdapter({
       instanceId: ProviderInstanceId.make("hermes-test"),
@@ -268,6 +269,41 @@ it.layer(testLayer)("HermesAdapter", (it) => {
     }),
   );
 
+  it.effect("projects Hermes session title callbacks as thread metadata", () =>
+    Effect.gen(function* () {
+      const { adapter } = yield* HermesAdapterTestHarness;
+      const threadId = ThreadId.make("hermes-title-thread");
+      const eventsFiber = yield* adapter.streamEvents.pipe(
+        Stream.take(1),
+        Stream.runCollect,
+        Effect.forkChild,
+      );
+      yield* Effect.yieldNow;
+
+      yield* adapter.receiveCallback({
+        protocolVersion: HERMES_BRIDGE_PROTOCOL_VERSION,
+        requestId: "title-callback-request",
+        deliveryId: "title-callback-delivery",
+        type: "session.title.updated",
+        chatId: "t3agent",
+        threadId,
+        sessionId: "session-title-thread",
+        title: "Renamed with /title",
+      });
+
+      const events = Array.from(yield* Fiber.join(eventsFiber));
+      NodeAssert.deepEqual(events[0], {
+        eventId: "hermes:title-callback-delivery:title",
+        provider: "hermes",
+        providerInstanceId: "hermes-test",
+        threadId,
+        createdAt: events[0]?.createdAt,
+        type: "thread.metadata.updated",
+        payload: { name: "Renamed with /title" },
+      });
+    }),
+  );
+
   it.effect("round-trips approval and clarification responses through the bridge", () =>
     Effect.gen(function* () {
       const { adapter, sent } = yield* HermesAdapterTestHarness;

apps/server/src/provider/Layers/HermesAdapter.ts

@@ -615,6 +615,15 @@ export const makeHermesAdapter = Effect.fn("makeHermesAdapter")(function* (
                 };
                 break;
               }
+              case "session.title.updated": {
+                const base = yield* eventBase(callback, threadId, "title");
+                yield* publish({
+                  ...base,
+                  type: "thread.metadata.updated",
+                  payload: { name: callback.title },
+                });
+                break;
+              }
               case "approval.request":
                 yield* rememberApproval(callback, threadId, context);
                 break;

apps/server/src/provider/hermes/HermesBridgeClient.test.ts

@@ -166,6 +166,45 @@ describe("HermesBridgeClient", () => {
     });
   });
 
+  it.effect("updates a Hermes session title through the dedicated endpoint", () => {
+    const targetThreadId = ThreadId.make("00000000-0000-4000-8000-000000000003");
+    const { client, execute } = makeClient(() =>
+      Response.json({
+        protocolVersion: 1,
+        requestId: "title-request",
+        status: "accepted",
+        title: "Canonical Hermes title",
+      }),
+    );
+
+    return Effect.gen(function* () {
+      const result = yield* client.updateSessionTitle({
+        protocolVersion: HERMES_BRIDGE_PROTOCOL_VERSION,
+        requestId: HermesBridgeRequestId.make("title-request"),
+        type: "session.title.update",
+        sessionId: HermesBridgeSessionId.make("session-1"),
+        targetThreadId,
+        title: "  Canonical Hermes title  ",
+      });
+
+      assert.strictEqual(result.title, "Canonical Hermes title");
+      const call = execute.mock.calls[0];
+      assert.ok(call);
+      const [request] = call;
+      assert.strictEqual(request.method, "POST");
+      assert.strictEqual(new URL(request.url).pathname, "/v1/sessions/title");
+      assert.strictEqual(request.headers["idempotency-key"], "title-request");
+      assert.deepStrictEqual(jsonBody(request), {
+        protocolVersion: 1,
+        requestId: "title-request",
+        type: "session.title.update",
+        sessionId: "session-1",
+        targetThreadId,
+        title: "  Canonical Hermes title  ",
+      });
+    });
+  });
+
   it.effect("deletes only the child session correlated to its T3 thread", () => {
     const targetThreadId = ThreadId.make("00000000-0000-4000-8000-000000000002");
     const sessionId = HermesBridgeSessionId.make("t3-child");
@@ -223,6 +262,7 @@ describe("HermesBridgeClient", () => {
         protocolVersion: 1,
         requestId: "request-interrupt",
         type: "turn.interrupt",
+        chatId: "t3agent",
         threadId: "thread-1",
       }),
     ],

apps/server/src/provider/hermes/HermesBridgeClient.ts

@@ -6,6 +6,8 @@ import {
   HermesBridgeSessionForkRequest,
   HermesBridgeSessionForkResponse,
   HermesBridgeSessionListResponse,
+  HermesBridgeSessionTitleUpdateRequest,
+  HermesBridgeSessionTitleUpdateResponse,
   type HermesBridgeT3ToHermesRequest,
 } from "@t3tools/contracts/hermesBridge";
 import * as Effect from "effect/Effect";
@@ -33,6 +35,9 @@ export interface HermesBridgeClient {
   readonly deleteSession: (
     request: HermesBridgeSessionDeleteRequest,
   ) => Effect.Effect<HermesBridgeAcknowledgement, ProviderAdapterRequestError>;
+  readonly updateSessionTitle: (
+    request: HermesBridgeSessionTitleUpdateRequest,
+  ) => Effect.Effect<HermesBridgeSessionTitleUpdateResponse, ProviderAdapterRequestError>;
 }
 
 function requestPath(request: HermesBridgeT3ToHermesRequest): string {
@@ -127,6 +132,18 @@ export function makeHermesBridgeClient(input: {
       ),
   );
 
+  const updateSessionTitle = Effect.fn("HermesBridgeClient.updateSessionTitle")(
+    (request: HermesBridgeSessionTitleUpdateRequest) =>
+      HttpClientRequest.post(`${baseUrl}/v1/sessions/title`).pipe(
+        authorize,
+        HttpClientRequest.setHeader("idempotency-key", request.requestId),
+        HttpClientRequest.bodyJsonUnsafe(request),
+        execute.execute,
+        Effect.flatMap(HttpClientResponse.schemaBodyJson(HermesBridgeSessionTitleUpdateResponse)),
+        Effect.mapError(mapRequestError("session.title.update")),
+      ),
+  );
+
   const send: HermesBridgeClient["send"] = (request) =>
     HttpClientRequest.post(`${baseUrl}${requestPath(request)}`).pipe(
       authorize,
@@ -137,5 +154,12 @@ export function makeHermesBridgeClient(input: {
       Effect.mapError(mapRequestError(request.type)),
     );
 
-  return { getCapabilities, listSessions, forkSession, deleteSession, send };
+  return {
+    getCapabilities,
+    listSessions,
+    forkSession,
+    deleteSession,
+    updateSessionTitle,
+    send,
+  };
 }

apps/server/src/provider/hermes/HermesBridgeRegistry.ts

@@ -17,7 +17,10 @@ export class HermesBridgeRegistryError extends Schema.TaggedErrorClass<HermesBri
 export interface HermesBridgeReceiver {
   readonly token: string;
   readonly receive: (payload: unknown) => Effect.Effect<unknown, ProviderAdapterError>;
-  readonly client?: Pick<HermesBridgeClient, "listSessions" | "forkSession" | "deleteSession">;
+  readonly client?: Pick<
+    HermesBridgeClient,
+    "listSessions" | "forkSession" | "deleteSession" | "updateSessionTitle"
+  >;
 }
 
 export interface HermesBridgeRegistration {
@@ -60,7 +63,7 @@ export const unregister = Effect.fn("HermesBridgeRegistry.unregister")(function*
 export const getClient = Effect.fn("HermesBridgeRegistry.getClient")(function* (
   instanceId: ProviderInstanceId,
 ): Effect.fn.Return<
-  Pick<HermesBridgeClient, "listSessions" | "forkSession" | "deleteSession">,
+  Pick<HermesBridgeClient, "listSessions" | "forkSession" | "deleteSession" | "updateSessionTitle">,
   HermesBridgeRegistryError
 > {
   const receiver = registrations.get(instanceId)?.receiver;