fix: derive Workbench rail titles from Kafka index

internal/workbench/http.ts

@@ -73,14 +73,26 @@ function requireAuthorization(request: Request, options: { snapshot?: unknown; a
   if (!expected || actual !== expected) throw Object.assign(new Error("Workbench API internal authentication failed"), { code: "auth_required" });
 }
 
-async function nativeSessionList(options: { snapshot?: () => Promise<any>; mode?: WorkbenchMode }, url: URL) {
+async function nativeSessionList(options: { snapshot?: () => Promise<any>; mode?: WorkbenchMode; kafkaEventBridge?: any }, url: URL) {
   const state = await requiredSnapshot(options);
   const owner = text(url.searchParams.get("ownerUserId"));
+  const kafkaSummary = options.mode === "agentrun-native" ? options.kafkaEventBridge?.workbenchSessionSummaries?.() : null;
+  const kafkaSummaryBySession = new Map((Array.isArray(kafkaSummary?.sessions) ? kafkaSummary.sessions : []).map((session: any) => [text(session.sessionId), session]));
   const sessions = Object.values(state.sessions)
     .filter((session: any) => !owner || session.ownerUserId === owner)
-    .map((session: any) => ({ ...session, firstUserMessagePreview: firstUserMessagePreview(session.messages) ?? (text(session.firstUserMessagePreview) || null) }))
+    .map((session: any) => {
+      const summary = kafkaSummaryBySession.get(text(session.sessionId)) as any;
+      const nativeTestPreview = options.mode === "agentrun-native" ? null : firstUserMessagePreview(session.messages) ?? (text(session.firstUserMessagePreview) || null);
+      return {
+        ...session,
+        firstUserMessagePreview: text(summary?.firstUserMessagePreview) || nativeTestPreview,
+        lastUserMessageAt: text(summary?.lastUserMessageAt) || null,
+        updatedAt: text(summary?.lastUserMessageAt) || session.updatedAt
+      };
+    })
     .sort((left: any, right: any) => String(right.updatedAt).localeCompare(String(left.updatedAt)));
-  return json(200, { ok: true, status: "ready", sessions, count: sessions.length, mode: options.mode ?? "native-test" });
+  const warnings = kafkaSummary?.warning ? [kafkaSummary.warning] : [];
+  return json(200, { ok: true, status: "ready", sessions, count: sessions.length, warnings, mode: options.mode ?? "native-test" });
 }
 async function nativeSessionDetail(options: { snapshot?: () => Promise<any>; mode?: WorkbenchMode }, sessionId: string, messagesOnly: boolean) {
   const state = await requiredSnapshot(options);

internal/workbench/workbench.test.ts

@@ -103,6 +103,35 @@ describe("Workbench native HTTP adapter", () => {
     });
   });
 
+  test("AgentRun native session list uses Kafka index summaries instead of admission messages", async () => {
+    const app = createWorkbenchHttpApp({
+      mode: "agentrun-native",
+      kafkaEventBridge: {
+        workbenchSessionSummaries() {
+          return { ok: true, sessions: [{ sessionId: "ses_title", firstUserMessagePreview: "Kafka title", lastUserMessageAt: "2026-07-20T01:00:00.000Z" }] };
+        }
+      },
+      async dispatch() { return { ok: true }; },
+      async snapshot() {
+        return {
+          sessions: {
+            ses_title: {
+              sessionId: "ses_title",
+              updatedAt: "2026-07-20T00:00:00.000Z",
+              messages: [{ role: "user", content: "admission snapshot title" }]
+            }
+          },
+          turns: {}
+        };
+      }
+    });
+
+    const response = await app.fetch(new Request("http://native.test/v1/workbench/sessions"));
+    expect(await response.json()).toMatchObject({
+      sessions: [{ sessionId: "ses_title", firstUserMessagePreview: "Kafka title", lastUserMessageAt: "2026-07-20T01:00:00.000Z" }]
+    });
+  });
+
   test("authorizes only the Workbench navigation entry", async () => {
     const app = createWorkbenchHttpApp({
       async dispatch() { return { ok: true }; },