Bug type

Regression (worked before, now fails)

Summary

Version

OpenClaw 2026.3.8

Description

The sessions_spawn LLM tool fails when spawning ACP sessions with:

spawnedBy is only supported for subagent:* sessions

This was introduced in 3.8 by the "ACP spawned-session lineage" feature (CHANGELOG #40137). The /acp spawn Discord command works fine — only the sessions_spawn tool path is affected.

Root cause

spawnAcpDirect() (called by sessions_spawn) passes spawnedBy: requesterInternalKey to sessions.patch:

// compact-D3emcZgv.js:27350
await callGateway({
  method: "sessions.patch",
  params: {
    key: sessionKey,
    spawnedBy: requesterInternalKey,
    ...params.label ? { label: params.label } : {}
  },
  timeoutMs: 1e4
});

However, the validation in sessions.patch only allows spawnedBy for subagent:* session keys:

// gateway-cli-CbAOelvx.js:9050
if (!isSubagentSessionKey(storeKey))
  return invalid("spawnedBy is only supported for subagent:* sessions");

ACP session keys have the format agent:{id}:acp:{uuid}, which doesn't match the subagent: prefix check.

The same issue applies to the spawnDepth validation immediately below.

Why /acp spawn works

handleAcpSpawnAction (the Discord command handler) calls sessions.patch without spawnedBy, so it bypasses this validation entirely.

Fix suggestion

isAcpSessionKey() already exists in session-key-*.js (exported as S) and correctly matches acp:* session keys. The validation should accept both:

if (!isSubagentSessionKey(storeKey) && !isAcpSessionKey(storeKey))
  return invalid("spawnedBy is only supported for subagent:* or acp:* sessions");

Same for the spawnDepth check a few lines below.

Reproduction

1. Configure an ACP agent (e.g. claude via acpx)
2. Have an LLM agent call sessions_spawn with runtime="acp", agentId="claude", thread=true, mode="session"
3. Observe the error: spawnedBy is only supported for subagent:* sessions

Using /acp spawn claude from Discord works as expected.

Workaround

Patch the two gateway-cli-*.js files to add isAcpSessionKey to the import and validation. Must clear NODE_COMPILE_CACHE and restart after patching.

Steps to reproduce

Steps to reproduce:

1. Configure an ACP agent (e.g. claude via acpx backend)
2. Have an LLM agent call the sessions_spawn tool with runtime="acp", agentId="claude", thread=true, mode="session"
3. Observe error: spawnedBy is only supported for subagent:* sessions

Note: /acp spawn claude (Discord command) works fine — only the sessions_spawn tool path is affected.

Expected behavior:
sessions_spawn should successfully create an ACP session and bind it to a Discord thread, the same way /acp spawn does. The spawnedBy
validation in sessions.patch should accept ACP session keys (agent:{id}:acp:{uuid}) in addition to subagent keys.

Expected behavior

sessions_spawn should successfully create an ACP session and bind it to a Discord thread, the same way /acp spawn does.

Actual behavior

sessions.patch rejects with spawnedBy is only supported for subagent:* sessions because the validation only checks
isSubagentSessionKey() but not isAcpSessionKey(). ACP session keys have format agent:{id}:acp:{uuid} which doesn't match the
subagent: prefix.

OpenClaw version

2026.03.08

Operating system

Debian

Install method

npm

Logs, screenshots, and evidence

Impact and severity

No response

Additional information

No response