Bug type

Regression (worked before, now fails)

Summary

After updating to v2026.3.22, ACP stopped working even though the standalone host acpx CLI was still healthy. The failure was in OpenClaw ACP backend discovery/registration, not in the acpx binary itself.

Steps to reproduce

1. Start from a setup using ACP backend acpx
2. Update OpenClaw to v2026.3.22
3. Try spawning an ACP session through OpenClaw
4. Example host-side check:

acpx claude sessions new

This succeeds
5. Example OpenClaw ACP path:

• sessions_spawn(runtime="acp", agentId="claude", ...)

Expected behavior

If acp.backend = "acpx" is configured and ACP was working before update, OpenClaw should continue to register and use the acpx backend normally after upgrading.

Actual behavior

OpenClaw fails ACP dispatch with:

ACP runtime backend is not configured. Install and enable the acpx runtime plugin.

At the same time, the host acpx CLI still works, which suggests the regression is in OpenClaw plugin discovery / backend registration, not in the harness binary.

OpenClaw version

2026.3.22

Operating system

Ubuntu Linux

Install method

npm/pnpm-style local install on host machine (state under ~/.openclaw/)

Model

Primary agent model in this environment is GPT-5.4, but the ACP failure occurs before model execution. The failing ACP target in testing was claude.

Provider / routing chain

OpenClaw → ACP runtime backend acpx → host acpx CLI

Additional provider/model setup details

OpenClaw → ACP runtime backend acpx → host acpx CLI

Additional provider/model setup details

• acp.enabled = true
• acp.dispatch.enabled = true
• acp.backend = "acpx"
• host acpx command is already installed and working
• docs still reference plugins.entries.acpx.enabled = true

Logs, screenshots, and evidence

Host CLI works:

acpx claude sessions new

OpenClaw ACP fails with:

ACP runtime backend is not configured. Install and enable the acpx runtime plugin.

doctor also reported a contradictory state after update:

plugins.entries.acpx: plugin not found: acpx (stale config entry ignored; remove it from plugins config)

This makes the post-update behaviour inconsistent:

• ACP still expects backend acpx
• docs still reference plugins.entries.acpx
• doctor/runtime may treat acpx as missing/stale

Impact and severity

High for workflows that depend on ACP sessions.

Standalone acpx remains usable, but OpenClaw loses the ability to route ACP work normally until the acpx plugin/backend layer is restored manually.

Additional information

ACP only came back after restoring/installing the OpenClaw acpx plugin again and pointing it at the already-working host acpx command.

That suggests the regression is in one of these areas:

• bundled plugin presence
• plugin discovery
• ACP backend registration after update

—not in the acpx CLI itself.