acp: add regression coverage and smoke-test docs

docs/tools/acp-agents.md

@@ -246,6 +246,46 @@ Interface details:
 - `streamTo` (optional): `"parent"` streams initial ACP run progress summaries back to the requester session as system events.
   - When available, accepted responses include `streamLogPath` pointing to a session-scoped JSONL log (`<sessionId>.acp-stream.jsonl`) you can tail for full relay history.
 
+### Operator smoke test
+
+Use this after a gateway deploy when you want a quick live check that ACP spawn
+is actually working end-to-end, not just passing unit tests.
+
+Recommended gate:
+
+1. Verify the deployed gateway version/commit on the target host.
+2. Confirm the deployed source includes the ACP lineage acceptance in
+   `src/gateway/sessions-patch.ts` (`subagent:* or acp:* sessions`).
+3. Open a temporary ACPX bridge session to a live agent (for example
+   `razor(main)` on `jpclawhq`).
+4. Ask that agent to call `sessions_spawn` with:
+   - `runtime: "acp"`
+   - `agentId: "codex"`
+   - `mode: "run"`
+   - task: `Reply with exactly LIVE-ACP-SPAWN-OK`
+5. Verify the agent reports:
+   - `accepted=yes`
+   - a real `childSessionKey`
+   - no validator error
+6. Clean up the temporary ACPX bridge session.
+
+Example prompt to the live agent:
+
+```text
+Use the sessions_spawn tool now with runtime: "acp", agentId: "codex", and mode: "run".
+Set the task to: "Reply with exactly LIVE-ACP-SPAWN-OK".
+Then report only: accepted=<yes/no>; childSessionKey=<value or none>; error=<exact text or none>.
+```
+
+Notes:
+
+- Keep this smoke test on `mode: "run"` unless you are intentionally testing
+  thread-bound persistent ACP sessions.
+- Do not require `streamTo: "parent"` for the basic gate. That path depends on
+  requester/session capabilities and is a separate integration check.
+- Treat thread-bound `mode: "session"` testing as a second, richer integration
+  pass from a real Discord thread or Telegram topic.
+
 ## Sandbox compatibility
 
 ACP sessions currently run on the host runtime, not inside the OpenClaw sandbox.

extensions/acpx/src/runtime.test.ts

@@ -127,6 +127,40 @@ describe("AcpxRuntime", () => {
     expect(promptArgs).toContain("--approve-all");
   });
 
+  it("serializes text plus image attachments into ACP prompt blocks", async () => {
+    const { runtime, logPath } = await createMockRuntimeFixture();
+
+    const handle = await runtime.ensureSession({
+      sessionKey: "agent:codex:acp:with-image",
+      agent: "codex",
+      mode: "persistent",
+    });
+
+    for await (const _event of runtime.runTurn({
+      handle,
+      text: "describe this image",
+      attachments: [{ mediaType: "image/png", data: "aW1hZ2UtYnl0ZXM=" }],
+      mode: "prompt",
+      requestId: "req-image",
+    })) {
+      // Consume stream to completion so prompt logging is finalized.
+    }
+
+    const logs = await readMockRuntimeLogEntries(logPath);
+    const prompt = logs.find(
+      (entry) =>
+        entry.kind === "prompt" &&
+        String(entry.sessionName ?? "") === "agent:codex:acp:with-image",
+    );
+    expect(prompt).toBeDefined();
+
+    const stdinBlocks = JSON.parse(String(prompt?.stdinText ?? ""));
+    expect(stdinBlocks).toEqual([
+      { type: "text", text: "describe this image" },
+      { type: "image", mimeType: "image/png", data: "aW1hZ2UtYnl0ZXM=" },
+    ]);
+  });
+
   it("preserves leading spaces across streamed text deltas", async () => {
     const runtime = sharedFixture?.runtime;
     expect(runtime).toBeDefined();

src/gateway/server.sessions.gateway-server-sessions-a.test.ts

@@ -463,6 +463,18 @@ describe("gateway server sessions", () => {
     expect(spawnedPatched.ok).toBe(true);
     expect(spawnedPatched.payload?.entry.spawnedBy).toBe("agent:main:main");
 
+    const acpPatched = await rpcReq<{
+      ok: true;
+      entry: { spawnedBy?: string; spawnDepth?: number };
+    }>(ws, "sessions.patch", {
+      key: "agent:main:acp:child",
+      spawnedBy: "agent:main:main",
+      spawnDepth: 1,
+    });
+    expect(acpPatched.ok).toBe(true);
+    expect(acpPatched.payload?.entry.spawnedBy).toBe("agent:main:main");
+    expect(acpPatched.payload?.entry.spawnDepth).toBe(1);
+
     const spawnedPatchedInvalidKey = await rpcReq(ws, "sessions.patch", {
       key: "agent:main:main",
       spawnedBy: "agent:main:main",