openclaw - 💡(How to fix) Fix [Bug]: ACP spawn on webchat creates usable shadow session plus broken agent:openclaw:acp:* lane; acpx ensureSession returns no events after sessions ensure/new [2 comments, 1 participants]

Bug type

Regression (worked before, now fails)

Beta release blocker

No

Summary

On webchat, /acp spawn openclaw creates a usable shadow session plus a broken canonical agent:openclaw:acp:* lane; ACPX returns no events after sessions ensure/new.

Steps to reproduce

1. Run OpenClaw 2026.4.1 with ACP enabled and backend set to acpx on Linux.
2. Open the Control UI on webchat.
3. Run /acp spawn openclaw.
4. Observe that the UI creates two artifacts for one spawn:
   • one usable top-level session that can answer normal prompts
   • one canonical lane under openclaw > acp:<uuid>
5. Open the canonical openclaw > acp:<uuid> lane.
6. Send a normal message or use /acp status.
7. Observe that the canonical ACP lane stalls or fails to initialize.
8. Check gateway logs and see acpx ensureSession failures such as "returned no events after sessions ensure" and "returned no events after sessions new".

Expected behavior

/acp spawn openclaw should create one working canonical ACP session under agent:openclaw:acp:<uuid>, and that lane should be directly usable in the Control UI.

Actual behavior

Each /acp spawn openclaw creates a pair of artifacts: one usable shadow session and one broken canonical openclaw > acp:<uuid> lane. The canonical lane fails with ACP initialization/backend errors and appears unable to obtain valid session identifiers from ACPX.

OpenClaw version

• OpenClaw 2026.4.1 - ACP backend: acpx - ACPX version: 0.4.0 - Host: Linux on Xeon - Surface: Control UI / webchat - Gateway probe: healthy during testing

Operating system

Linux 6.8.0-107-generic on Xeon server

Install method

npm global install (Node 22.22.2 via fnm)

Model

openai-codex/gpt-5.4

Provider / routing chain

OpenClaw -> configured OpenAI Codex provider -> gpt-5.4

Additional provider/model setup details

No response

Logs, screenshots, and evidence

acpx ensureSession repairing dead named session by resuming backend session:
  session=agent:openclaw:acp:46f367ca-4e16-478c-bada-19fd3f54578d
  cwd=/home/sam/.openclaw/workspace
  resumeSessionId=a18abb12-0887-4ef5-8ce4-dad4c9e96b73
  status=dead
  summary=queue owner unavailable

acpx ensureSession repairing dead named session by resuming backend session:
  session=agent:openclaw:acp:230889e4-fb31-44fe-aa81-d7c93bbbb7ab
  cwd=/home/sam/.openclaw/workspace
  resumeSessionId=be8a2438-f416-4c15-a474-5c262b3e1ff9
  status=dead
  summary=queue owner unavailable

acpx ensureSession returned no events after sessions ensure:
  session=agent:openclaw:acp:230889e4-fb31-44fe-aa81-d7c93bbbb7ab
  agent=openclaw
  cwd=/home/sam/.openclaw/workspace

acpx ensureSession returned no events after sessions ensure:
  session=agent:openclaw:acp:46f367ca-4e16-478c-bada-19fd3f54578d
  agent=openclaw
  cwd=/home/sam/.openclaw/workspace

acpx ensureSession returned no events after replacing dead session:
  session=agent:openclaw:acp:46f367ca-4e16-478c-bada-19fd3f54578d
  agent=openclaw
  cwd=/home/sam/.openclaw/workspace

acpx ensureSession returned no events after sessions new:
  session=agent:openclaw:acp:230889e4-fb31-44fe-aa81-d7c93bbbb7ab
  agent=openclaw
  cwd=/home/sam/.openclaw/workspace

acpx ensureSession returned no events after sessions new:
  session=agent:openclaw:acp:46f367ca-4e16-478c-bada-19fd3f54578d
  agent=openclaw
  cwd=/home/sam/.openclaw/workspace

Impact and severity

High. ACP lane creation on webchat is not functioning correctly for canonical agent:openclaw:acp:* sessions. Each /acp spawn openclaw creates a usable shadow session plus a broken canonical ACP lane, which makes the feature confusing and unreliable. This blocks normal ACP thread/lane setup and creates duplicate/broken session artifacts in the UI. Core chat still works, so this is not a total outage, but ACP session setup on this surface is effectively broken.

Additional information

Additional observations:

• /acp spawn ... --bind here reports "Conversation bindings are unavailable for webchat."
• Labels passed with /acp spawn ... --label ... do not appear in the Control UI picker; raw acp:<uuid> names remain.
• Cleaning stale agent:main:<uuid> ACP-like session entries made the picker cleaner but did not fix canonical agent:openclaw:acp:* lane establishment.