fix(gateway): build row metadata for single session lists

Refs #92057.

Build the request-scoped row metadata context for every non-empty sessions.list result, including limit=1, so single-row lists use the shared subagent metadata read index instead of direct per-row registry snapshot lookups. This keeps the existing single-row store child-session candidate optimization intact while removing the single-row metadata-cache gap.

Verification:
- node scripts/run-vitest.mjs src/gateway/session-utils.single-row-cache.test.ts --maxWorkers=1
- .agents/skills/autoreview/scripts/autoreview --mode branch --base origin/main
- Crabbox run_f89b56ffea83 / cbx_f1b1f5013225: OPENCLAW_CHECK_CHANGED_REMOTE_CHILD=1 OPENCLAW_CHANGED_LANES_RAW_SYNC=1 corepack pnpm check:changed
- GitHub PR checks clean on 1ba6619f2e

src/gateway/session-utils.single-row-cache.test.ts

@@ -72,7 +72,11 @@ const subagentRegistryReadMock = vi.hoisted(() => {
 
 vi.mock("../agents/subagent-registry-read.js", () => subagentRegistryReadMock);
 
-import { loadGatewaySessionRow } from "./session-utils.js";
+import {
+  listSessionsFromStore,
+  listSessionsFromStoreAsync,
+  loadGatewaySessionRow,
+} from "./session-utils.js";
 
 const MAIN_AGENT_ID = "main";
 const TEST_MODEL = "openai/gpt-5.4";
@@ -238,6 +242,62 @@ describe("single gateway session row child-session cache", () => {
     );
   });
 
+  test("builds shared subagent metadata context for single-row session lists", async () => {
+    await withSingleRowCacheStore(
+      "openclaw-single-row-list-context-",
+      "/tmp/openclaw-single-row-list-context",
+      async ({ now, storePath }) => {
+        const store: Record<string, SessionEntry> = {
+          "agent:main:discord:channel:parent": parentSession("parent", now),
+        };
+        const cfg: OpenClawConfig = {
+          agents: {
+            list: [
+              {
+                id: MAIN_AGENT_ID,
+                default: true,
+                workspace: "/tmp/openclaw-single-row-list-context",
+              },
+            ],
+            defaults: { model: { primary: TEST_MODEL } },
+          },
+        } as OpenClawConfig;
+
+        const syncListed = listSessionsFromStore({
+          cfg,
+          storePath,
+          store,
+          opts: { agentId: MAIN_AGENT_ID, limit: 1 },
+        });
+
+        expect(syncListed.sessions).toHaveLength(1);
+        expect(subagentRegistryReadMock.buildSubagentRunReadIndex).toHaveBeenCalledTimes(
+          1,
+        );
+        expect(
+          subagentRegistryReadMock.getSessionDisplaySubagentRunByChildSessionKey,
+        ).not.toHaveBeenCalled();
+
+        vi.clearAllMocks();
+
+        const asyncListed = await listSessionsFromStoreAsync({
+          cfg,
+          storePath,
+          store,
+          opts: { agentId: MAIN_AGENT_ID, limit: 1 },
+        });
+
+        expect(asyncListed.sessions).toHaveLength(1);
+        expect(subagentRegistryReadMock.buildSubagentRunReadIndex).toHaveBeenCalledTimes(
+          1,
+        );
+        expect(
+          subagentRegistryReadMock.getSessionDisplaySubagentRunByChildSessionKey,
+        ).not.toHaveBeenCalled();
+      },
+    );
+  });
+
   test("rebuilds store child candidates after same-object session store writes", async () => {
     await withSingleRowCacheStore(
       "openclaw-single-row-cache-write-version-",

src/gateway/session-utils.ts

@@ -2747,7 +2747,7 @@ export function listSessionsFromStore(params: {
       : undefined;
   const sharedRowContext =
     fullRowContext ??
-    (entries.length > 1 ? buildSessionListRowMetadataContext({ now }) : undefined);
+    (entries.length > 0 ? buildSessionListRowMetadataContext({ now }) : undefined);
 
   const sessions = entries.map(([key, entry], index) => {
     const includeTranscriptFields = index < sessionListTranscriptFieldRows;
@@ -2837,7 +2837,7 @@ export async function listSessionsFromStoreAsync(params: {
       : undefined;
   const sharedRowContext =
     fullRowContext ??
-    (entries.length > 1 ? buildSessionListRowMetadataContext({ now }) : undefined);
+    (entries.length > 0 ? buildSessionListRowMetadataContext({ now }) : undefined);
 
   const sessions: GatewaySessionRow[] = [];
   for (let i = 0; i < entries.length; i++) {