Environment

• OpenClaw: 2026.2.26 (bc50708)
• acpx: 0.1.13
• macOS arm64, Node 22.22.0
• Claude Code: 2.1.62

Symptom

Every sessions_spawn runtime="acp" agentId="claude" fails immediately with:

AcpRuntimeError: Internal error: code=ACP_TURN_FAILED

Session histories are empty — agents never execute a single line. Same failure for agentId="codex".

Root Cause Confirmed

acpx spawns the Claude Code queue owner process without a PTY. Claude Code uses Ink (React terminal UI) which requires raw mode TTY — it crashes immediately.

Error from Claude Code process:

ERROR: Raw mode is not supported on the current process.stdin, which Ink uses as input stream by default.

The spawn call in runtime-internals/process.ts is hardcoded:

return spawn(resolved.command, resolved.args, {
  cwd: params.cwd,
  env: process.env,
  stdio: ["pipe", "pipe", "pipe"],  // ← no PTY, hardcoded
  shell: resolved.shell,
});

How I Found It

• acpx exec works fine (different code path, no queue owner needed)
• acpx prompt fails because it starts a persistent queue owner which spawns claude — but without TTY it dies instantly
• Verbose output: agent needs reconnect → starting detached queue owner → immediate crash
• Also confirmed in gateway logs: --session "" (empty session name) because the queue owner never initialises

Additional Signals

Gateway logs on every restart:

acp startup identity reconcile (renderer=v1): checked=32 resolved=0 failed=32

/acp doctor reports healthy. openclaw doctor --fix ran but didn't resolve it.

Requested Fix

spawnWithResolvedCommand in runtime-internals/process.ts needs to support spawning with a pseudo-terminal (PTY) for harnesses like Claude Code that require raw mode TTY.

Workaround (current)

Using exec with pty:true and claude --dangerously-skip-permissions -p directly — works but bypasses the full ACP session management.