diff --git a/apps/server/src/routes/templates.ts b/apps/server/src/routes/templates.ts
index 5fd38f02..2bda494d 100644
--- a/apps/server/src/routes/templates.ts
+++ b/apps/server/src/routes/templates.ts
@@ -13,6 +13,7 @@ import {
   createStartupPins,
   parseOptionalStringArrayField,
 } from "./agent-startup.js";
+import type { AgentRecord } from "../agents/manager.js";
 import type { TemplateService } from "../templates/service.js";
 import { parseTemplateArgs } from "../templates/store.js";
 import {
@@ -88,6 +89,9 @@ function classifyErrorCode(message: string): number {
 type TemplateRouteDeps = {
   templateService: TemplateService;
   publishUiEvent: (event: unknown) => void;
+  withStreamFlag: <T extends AgentRecord>(
+    agent: T
+  ) => T & { hasStream: boolean };
 };
 
 export async function registerTemplateRoutes(
@@ -265,7 +269,7 @@ export async function registerTemplateRoutes(
         });
         deps.publishUiEvent({
           type: "agent.upsert",
-          agent: result.agent,
+          agent: deps.withStreamFlag(result.agent),
         });
         return { agent: result.agent };
       } catch (error) {
diff --git a/apps/server/src/server.ts b/apps/server/src/server.ts
index f1097967..8ae71d15 100644
--- a/apps/server/src/server.ts
+++ b/apps/server/src/server.ts
@@ -617,6 +617,7 @@ async function registerRoutes() {
   await registerTemplateRoutes(app, {
     templateService,
     publishUiEvent: (event) => uiEventBroker.publish(event as UiEvent),
+    withStreamFlag,
   });
 
   await registerMcpRoutes(app, {
diff --git a/apps/server/test/template-launch-publish.test.ts b/apps/server/test/template-launch-publish.test.ts
new file mode 100644
index 00000000..f3a9d7f2
--- /dev/null
+++ b/apps/server/test/template-launch-publish.test.ts
@@ -0,0 +1,87 @@
+/**
+ * The launch route's `agent.upsert` publish must carry the `hasStream` flag,
+ * like every other `agent.upsert` publish site. `applyAgentUpsert` on the web
+ * side replaces the cached agent wholesale, so an unflagged payload drops the
+ * field from the cached row.
+ */
+import {
+  afterAll,
+  beforeAll,
+  beforeEach,
+  describe,
+  expect,
+  it,
+  vi,
+} from "vitest";
+import Fastify, { type FastifyInstance } from "fastify";
+import fastifyMultipart from "@fastify/multipart";
+
+import { registerTemplateRoutes } from "../src/routes/templates.js";
+
+const LAUNCHED_AGENT = {
+  id: "agt_launched",
+  name: "launch-tmpl",
+  cwd: "/tmp",
+  status: "running",
+};
+
+let app: FastifyInstance;
+let publishUiEvent: ReturnType<typeof vi.fn>;
+let launchTemplate: ReturnType<typeof vi.fn>;
+
+beforeAll(async () => {
+  publishUiEvent = vi.fn();
+  launchTemplate = vi.fn(async () => ({
+    agent: LAUNCHED_AGENT,
+    templateId: "tmpl-1",
+    templateName: "launch-tmpl",
+  }));
+
+  app = Fastify();
+  await app.register(fastifyMultipart);
+  await registerTemplateRoutes(app, {
+    templateService: { launchTemplate } as never,
+    publishUiEvent,
+    withStreamFlag: ((agent: object) => ({
+      ...agent,
+      hasStream: true,
+    })) as never,
+  });
+  await app.ready();
+});
+
+afterAll(async () => {
+  await app.close();
+});
+
+beforeEach(() => {
+  publishUiEvent.mockClear();
+});
+
+describe("POST /api/v1/templates/:id/launch", () => {
+  it("publishes agent.upsert with the stream flag applied", async () => {
+    const res = await app.inject({
+      method: "POST",
+      url: "/api/v1/templates/tmpl-1/launch",
+      headers: { "content-type": "application/json" },
+      payload: {},
+    });
+
+    expect(res.statusCode).toBe(200);
+    expect(publishUiEvent).toHaveBeenCalledWith({
+      type: "agent.upsert",
+      agent: { ...LAUNCHED_AGENT, hasStream: true },
+    });
+  });
+
+  it("still returns the unflagged agent in the HTTP response", async () => {
+    const res = await app.inject({
+      method: "POST",
+      url: "/api/v1/templates/tmpl-1/launch",
+      headers: { "content-type": "application/json" },
+      payload: {},
+    });
+
+    expect(res.json()).toEqual({ agent: LAUNCHED_AGENT });
+  });
+});