feat: add endpoint to fetch indexed session metadata and implement corresponding service method

server/src/modules/ai-runtime/ai-runtime.routes.ts

@@ -492,6 +492,18 @@ router.get(
   }),
 );
 
+/**
+ * Returns one DB-indexed session metadata row.
+ */
+router.get(
+  '/sessions/:sessionId',
+  asyncHandler(async (req: Request, res: Response) => {
+    const sessionId = readPathParam(req.params.sessionId, 'sessionId');
+    const session = llmSessionsService.getIndexedSession(sessionId);
+    res.json(createApiSuccessResponse({ session }));
+  }),
+);
+
 /**
  * Triggers provider disk scans and refreshes the shared sessions table.
  */

server/src/modules/ai-runtime/services/sessions.service.ts

@@ -106,6 +106,21 @@ export const llmSessionsService = {
     return allSessions.filter((session) => session.provider === provider);
   },
 
+  /**
+   * Reads one indexed session metadata row.
+   */
+  getIndexedSession(sessionId: string) {
+    const session = sessionsDb.getSessionById(sessionId);
+    if (!session) {
+      throw new AppError(`Session "${sessionId}" was not found.`, {
+        code: 'SESSION_NOT_FOUND',
+        statusCode: 404,
+      });
+    }
+
+    return session;
+  },
+
   /**
    * Runs all provider indexers and updates `scan_state.last_scanned_at`.
    */

server/src/modules/ai-runtime/tests/sessions.test.ts

@@ -131,6 +131,44 @@ test('llmSessionsService.updateSessionCustomName validates existence before upda
   }
 });
 
+// This test covers fetching one indexed DB session metadata row from getSessionById.
+test('llmSessionsService.getIndexedSession returns DB session metadata', { concurrency: false }, () => {
+  const restoreGetById = patchMethod(sessionsDb, 'getSessionById', (sessionId: string) => (
+    sessionId === 'known-session'
+      ? {
+          session_id: 'known-session',
+          provider: 'claude',
+          workspace_path: '/tmp/workspace',
+          jsonl_path: '/tmp/workspace/session.jsonl',
+          created_at: '2026-04-01T00:00:00.000Z',
+          updated_at: '2026-04-02T00:00:00.000Z',
+        }
+      : null
+  ));
+
+  try {
+    const session = llmSessionsService.getIndexedSession('known-session');
+    assert.deepEqual(session, {
+      session_id: 'known-session',
+      provider: 'claude',
+      workspace_path: '/tmp/workspace',
+      jsonl_path: '/tmp/workspace/session.jsonl',
+      created_at: '2026-04-01T00:00:00.000Z',
+      updated_at: '2026-04-02T00:00:00.000Z',
+    });
+
+    assert.throws(
+      () => llmSessionsService.getIndexedSession('missing-session'),
+      (error: unknown) =>
+        error instanceof AppError &&
+        error.code === 'SESSION_NOT_FOUND' &&
+        error.statusCode === 404,
+    );
+  } finally {
+    restoreGetById();
+  }
+});
+
 // This test covers delete behavior using only DB jsonl_path, including invalid id validation.
 test('llmSessionsService.deleteSessionArtifacts validates ids and deletes disk/db artifacts', { concurrency: false }, async () => {
   const tempRoot = await fs.mkdtemp(path.join(os.tmpdir(), 'llm-delete-session-'));