v0.9.0 to v0.10.0

---

name: acpx-faq

description: Run coding agents (codex, claude, agy) through the acpx ACP CLI - one-shot dispatch into named sessions you can watch live. Use before launching or prompting a subagent, or when a command fails, a session is missing, or a prompt is lost.

metadata:

categories: "agents, operations"

topics: "acpx, acp, agent-orchestration, troubleshooting, headless-agents"

openclaw:

homepage: https://github.com/tenequm/skills/tree/main/skills/acpx-faq

emoji: "🔌"

---

# acpx FAQ

Drive coding agents headlessly through [acpx](https://github.com/openclaw/acpx) (>= 0.19.3).

## Syntax authority

Syntax comes from the binary, not this file. `acpx --skill show acpx` is the vendor

transcript. Retrieve in this order:

1. `acpx --help` / `acpx <cmd> --help` - the flags you are about to compose.

2. One topic: `acpx --skill show acpx | rg -B2 -A12 '<term>'`, or a section:

`acpx --skill show acpx | sed -n '/^## Sessions/,/^## /p'`.

3. Authoring something novel (a flow, an embedded runtime): dump ONCE to a scratch

file and grep that file.

This file repeats nothing the reference covers. It carries only what the reference

lacks: exit codes, failure semantics, traps, and per-agent recipes. If a syntax

question is not answered here, it is answered there - go get it, never guess a flag.

shipped reference omits.

## When this lane

acpx is the headless out-of-process executor lane: another agent, vendor or account,

driven from a script or from another agent, in a plain terminal, ssh or cron.

In-session fan-out stays on the harness's own subagent tool.

## Invariants

1. **Global flags precede the agent subcommand** (`--cwd`, `--model`, `--approve-all`,

after the agent exits **1** with `error: unknown option`; a bad flag *before* the

agent exits **2**.

2. **`-s <name>` never creates a session.** It resolves one, walking from `--cwd` up

to the nearest `.git` - a directory *or file*, so each worktree and submodule is its

own boundary; outside git only the exact `--cwd` is checked. No match exits **4**.

Create first with `sessions ensure --name <n>` in the same directory.

3. **`status` is not a turn signal.** It probes the queue-owner process, never the

agent, and keeps saying `running` after the turn has ended. Never gate automation

on it.

4. **Permission flags are not a sandbox.**

- **claude**: the adapter starts in `permissions.defaultMode` from the Claude

settings (`acceptEdits` / `auto` approve edits without asking). Only what that

mode escalates reaches acpx as a permission request - `--deny-all` refuses those

(exit 5), but an auto-approved edit never asks.

- **codex**: writes inside its workspace-write sandbox (rooted at `--cwd`, plus temp

dirs) raise no request, so `--deny-all` still writes; outside fails with

`Operation not permitted`. Network is off unless `config.toml` enables

`network_access`. `--approve-all` does not change the adapter's mode

(`INITIAL_AGENT_MODE=read-only|agent|agent-full-access` does).

- `--allowed-tools` / `--max-turns` reach only claude (and qoder); codex and agy

The real filesystem control is which `--cwd` you hand it.

5. **`[done] end_turn` and exit 0 are not proof of success.** A content-filter kill,

an MCP load failure, an API error (a 401 during a token refresh, a 400 model

rejection), or a truncated turn all end that way. Read the stream, or require the

agent to write a result file you can check. Before a fan-out, one cheap `exec`

("Reply OK") per agent and model catches auth and model errors.

6. **A persistent session holds a resident process stack only while it is busy or

warm.** Every `-s` prompt elects a queue owner holding `npm exec -> node <adapter>

-> <agent>` (plus the agent's MCP servers), roughly 550-650 MB before MCP. After

the idle TTL (default 300s) the owner exits and the session stays resumable; the

next prompt respawns it. `sessions close` ends the task - chain it into the launch

line (see Per agent) so teardown never depends on anyone remembering; `--ttl 0`

removes the self-reap. See Teardown.

## Per agent

**Dispatch one-shot: `sessions ensure && prompt && sessions close`, one chained

call.** One named session per task, one prompt, closed when the result file is read.

The `&&` chain makes teardown mechanical - nothing reaps open records, and orphans

come from unchained closes - while a turn that fails nonzero (timeout 3, permission 5)

skips the close on its own, leaving the session open for recovery (see Talking to a

live session). An externally cancelled turn still exits 0, so the result file, not

the exit code, is the success check (invariant 5). Do not park a session for expected

follow-ups: a blocker's state lives outside the conversation (creds are machine-level,

partials belong in the result file) - answer it with a fresh session fed the brief

plus that file. Rework - a correction, review, or polish of a session's output - also

gets a fresh session: an agent re-reading its own context misses what fresh eyes

catch. Never `--no-wait` into a session whose launch line carries the close: owner

shutdown drops pending prompts silently and cancels the active turn (verified 0.19.4);

a blocking prompt before the close is safe. Use `exec` for a stateless answer with no

record worth keeping (a preflight "Reply OK"). Sessions key on agent command + cwd +

name; give each parallel executor its own name and, when it writes files, its own

directory (ideally one worktree).

Adapters run through `npm exec`. A fresh HOME per job re-downloads them (hundreds of

MB each); share one `npm_config_cache`. On macOS a fresh HOME also hides the login

Keychain: the claude adapter fails `RUNTIME: Unable to validate model: Could not

resolve authentication method` - keep HOME. The npx cache also reuses stale builds -

pin exact adapter versions in `~/.acpx/config.json` (`agents.<name>.argv`). A pin

freezes which model ids work, and changing it re-keys sessions (see Sessions).

Executors inherit the user's global instruction files (claude's `~/.claude/CLAUDE.md`,

codex's global `AGENTS.md`). A rule like "ask before editing" ends a headless turn on

a question with no work done - open every brief with "act now; do not stop to ask or

end on a question".

### agy / Antigravity

The built-in `acpx antigravity` (0.17.1+) runs `agy_acp_server.par` **from PATH**,

and the copy Antigravity installs under `~/.local/lib/antigravity-acp/` is not on

PATH - bare `acpx antigravity` exits 1 with `Failed to spawn agent command:

agy_acp_server.par`. Prepend that directory to PATH, set `agents.antigravity.argv`,

or use `--agent <path>`. The built-in `gemini` agent is the *public Gemini CLI* - a

different product. The `.par` comes from the Antigravity install or the official ACP

registry archive; keep it beside its `localharness_external` helper from the same

release (a missing helper only logs `Localharness not found.` and carries on), or

point `ANTIGRAVITY_HARNESS_PATH` at it. Neither acpx nor `agy update` refreshes the

`.par`: compare its `--version` `Build label:` with the

[ACP registry](https://github.com/agentclientprotocol/registry/blob/main/antigravity-acp/agent.json)

```bash

D=/abs/real/dir # must exist: roots resolve through realpath

acpx --agent ~/.local/lib/antigravity-acp/agy_acp_server.par \

exec "Carry out $D/brief.md. Write your report to $D/report.md."

```

- **`--approve-all` is mandatory.** Without it every write is refused: exit 5 (or a

stall to exit 3), with `[done] end_turn` still printed and no report.

- **Fixed-choice questions fail the prompt with exit 5 even under `--approve-all`**

(final line `Antigravity requested a user answer...`) - for `--agent` launches too.

Write briefs that never need a user choice.

- **agy reads sibling files unprompted** - agents sharing a directory reproduce each

other's output. One directory per agent, and checksum any rerun before believing an

agreement number.

- **Auth: needs `auth.type` in `<GEMINI_HOME>/antigravity-acp/settings.json`** (one-time):

```bash

mkdir -p ~/.gemini/antigravity-acp

echo '{"auth":{"type":"oauth-personal"}}' > ~/.gemini/antigravity-acp/settings.json

```

Without it: immediate `[error] RUNTIME: Authentication required` (exit 1). With it

but never signed in: `session/new` blocks on a browser sign-in until `--timeout`

(exit 3) - sign in once interactively. The server's credential is separate from the

`agy` CLI's: the macOS Keychain (service `gemini`, account `antigravity-acp`), or

`<GEMINI_HOME>/antigravity-acp/acp_token.json` off macOS or with

`AGY_ACP_FORCE_FILE_STORAGE=1`. `GEMINI_HOME` alone does not isolate the macOS

credential. An entitlement problem is server-side - do not "fix" it by switching to

`gemini-api-key` or a GCP project (separate billing, not fixes).

- **Never pass a positional agent with `--agent`** - exit **2**.

- **Verification prompts: demand a bare reply and read the whole log.** agy routes

answers into brain artifact files, so a `tail` cannot tell "no tools" from

"answered elsewhere". Add "Do not create any files".

- **agy hides MCP failures inside a successful-looking turn** - exit 0, `[done]

end_turn`, and the whole reply is `The MCP server '<name>' failed to initialize: ...`.

Grep for `failed to initialize`.

- **Prefer `exec`.** A server death mid-checkpoint has been reported to break a saved

conversation for good (`could not find doneCh for checkpoint`); the only reported

recovery is deleting `~/.gemini/antigravity-acp/conversations/<id>.db`.

#### Linux / NixOS

The built-in agent adds the required `--uid=` itself. NixOS additionally needs a CA

bundle, so point `--agent` (or `agents.antigravity.argv`) at a wrapper

(`~/.local/bin/agy-acp-server`):

```bash

#!/usr/bin/env bash

export SSL_CERT_FILE=/etc/ssl/certs/ca-certificates.crt

exec ~/.local/lib/antigravity-acp/agy_acp_server.par --uid= "$@"

```

Without `SSL_CERT_FILE` the `.par`'s embedded OpenSSL has no valid CA paths; its local

proxy reports `502 Bad Gateway: Failed to connect to backend API` and the turn still

ends `[done] end_turn` with **exit 0** (invariant 5). The real

`CERTIFICATE_VERIFY_FAILED` appears only under `--alsologtostderr`.

### codex

```bash

D=/abs/dir

acpx --cwd "$D" codex sessions ensure --name work # idempotent; -s cannot create

acpx --cwd "$D" codex set model gpt-5.6-sol -s work

acpx --cwd "$D" codex set reasoning_effort high -s work

{ acpx --cwd "$D" --approve-all --timeout 5400 --suppress-reads \

codex -s work 'Carry out ./brief.md. Write your report to ./report.md.' && \

acpx --cwd "$D" codex sessions close work; } > run.log 2>&1 &

# a failed turn skips the close - re-prompt -s work to recover, then close yourself

```

One-shot: `exec --config-option reasoning_effort=low` sets model and effort inline

(0.14.0+), applied after `--model` and before the prompt.

- The codex adapter (`@agentclientprotocol/codex-acp`) floats on `^1.1.5` - behavior

can change without an acpx upgrade, but the breaking 2.x is out of range. A stale

adapter rejects newer model ids: `[error] RUNTIME: Invalid params` at

`session/set_config_option` (exit 1), or a 400 `model is not supported` that still

ends `[done] end_turn`, exit 0. Pin a current one:

- **OpenAI's content filter kills benign turns** that end clean (`[done] end_turn`,

exit 0). Vocabulary like race / sweep / exploit / attack in a filename, comment or

prompt triggers it. Read the transcript tail before believing completion; recover by

re-prompting the same `-s <name>` (context survives unless the reconnect fails -

acpx then silently falls back to `session/new`) with the artifact renamed

neutrally and the remaining steps listed explicitly.

- **Re-prompting the same name queues behind the current turn** - the recovery path

after a content-filter kill (above), not a dispatch pattern; close once recovered.

- **MCP servers still starting when codex builds its tool list are dropped** (1s shared

grace). `mcp_optional_startup_grace_ms = 0` in `config.toml` waits for each server's

own `startup_timeout_sec` instead.

### claude

```bash

D=/abs/dir

acpx --cwd "$D" --model claude-opus-5 claude sessions ensure --name work

acpx --cwd "$D" claude set effort high -s work # optional; after any model change

{ acpx --cwd "$D" --model claude-opus-5 --approve-all --suppress-reads --timeout 2400 \

claude -s work -f /abs/brief.md && \

acpx --cwd "$D" claude sessions close work; } >> run.log 2>&1 &

# failed turn (exit 3/5) = close skipped: re-prompt -s work to recover with context,

# then close; anything after a clean close is a fresh session fed the result file

```

- **Effort is `set effort <level>`**; `set reasoning_effort` is the codex name and

returns `Internal error` on claude. A model switch resets effort - set model first.

- **Pass the model with `--model <exact id>` at session creation.** `set model`

fuzzy-matches against the adapter's advertised list and can silently land on a

different entry (e.g. `opus[1m]`); only an id with no match fails

(`Invalid value for config option model`). An unknown `--model` fails with

`RUNTIME: Model '<id>' not found`. Quote ids with brackets (`'...[1m]'`) - globs.

- **The bundled Claude Code is whatever the adapter pins.** Built-in adapter

- **User settings are excluded on purpose** - user skills are missing (`/polish`

"isn't available"). Fix with `ACPX_CLAUDE_INCLUDE_USER_SETTINGS=1`. acpx reads it

from its own environment and re-applies settings whenever the session's process

spawns (create, load, resume); a live owner keeps what it started with, so after

changing it close the session or let the owner idle out, then prompt again. A

`--cwd` under `$HOME` still loads `~/.claude/CLAUDE.md` through the ancestor

CLAUDE.md walk.

- **Second account**: export `CLAUDE_CONFIG_DIR` and `CLAUDE_SECURESTORAGE_CONFIG_DIR`

before `acpx`; the child inherits them. Set them on **every** call, not only the

first - whichever call respawns an idle session decides its account. A tiny wrapper

script that exports them and execs acpx makes that hard to forget.

- **Edits need no `--approve-all` when Claude's own `permissions.defaultMode` is

`auto` or `acceptEdits`** (invariant 4); pass it on every prompt anyway so

escalated requests are not denied.

- **The child's harness refuses long foreground sleeps** (`sleep 90` blocked outright),

so a child cannot own a long wait or poll loop - and a loop it backgrounds dies when

its owner exits. Long waits belong to the driving side (`sessions watch`, a

result-file poll).

- **Subagents inside a child work** (verified with the Agent tool), but an executor

that spawns them in the background can end its turn before they report -

`[done] end_turn`, exit 0, no report. The brief must say to wait for every subagent

and write the report before the final message, and never to end a turn with a

background loop running.

- **Prompt text the driving harness blocks** (a hook or classifier reading a brief

that mentions gates, secrets or approvals): send every prompt as `-f <file>`.

## Sessions

- Sessions key on **(agent command, absolute cwd, optional name)** - parallel

executors need their own directories, which also keeps per-session model and effort

settings from racing.

- **Changing `agents.<name>.argv` (a pin bump) or a `<cwd>/.acpxrc.json` override

changes the agent command, so existing `-s` sessions stop resolving (exit 4).**

adapter, the MCP set, or permission defaults - `acpx --cwd <dir> config show`

before pointing acpx at a repo you do not control.

- `sessions close` is the teardown verb: marks the record closed, sends ACP

`session/close`, takes down the owner and adapter processes (see Teardown). Also

required before `codex resume` and `sessions export`.

- A session whose cwd you deleted still closes with `--cwd <old path>`.

## Completion

`status` states (the shipped reference has no state table): `running` (JSON: `alive`

- the owner's socket answers), `idle` (no owner, including one that was killed),

`dead` (an owner lease remains but is unhealthy, or the recorded exit was abnormal),

`no-session`. `running` holds for the whole idle TTL after a turn ends - a loop

waiting for `idle` spins past real completion (invariant 3). What is actually correct:

- `acpx <agent> sessions watch -s <n>`: its `turn_result` event (`completed`,

`cancelled`, `failed`) is the settlement signal. Without `--cursor` it first replays

the retained window, earlier turns included - match the `requestId` from

`[queued] <id>`, and break out yourself (it never exits on an open session).

`WATCH_OUTCOME_UNKNOWN` means the owner died mid-turn - the prompt may have run;

check before resubmitting (`requestId` is not an idempotency key: a resubmit runs

twice). `WATCH_OWNER_UNSUPPORTED` is an older owner - close it;

- the foreground stream's terminating `[done] end_turn`, plus the process exit code;

- `sessions show <n>` (`lastActivity`, `historyEntries`), `sessions history <n>`, and

`sessions read <n> --tail N` (shows in-flight tool calls);

- best: a **result file** the brief required the agent to write - poll for the file.

`--no-wait` acknowledges enqueueing (`[queued] <id>`; nothing is printed under

`--format quiet`), which is neither delivery nor completion - behind a running turn

the prompt waits for the turn boundary.

From a Claude Code driver, run `sessions watch` under the Monitor tool so each turn

arrives as a notification:

```bash

acpx --format json --cwd "$D" claude sessions watch -s work --cursor "$LAST" \

| jq --unbuffered -c 'select(.type=="turn_started" or .type=="turn_result")

| {type, requestId, status: .result.status}'

```

Supervise a backgrounded text-format run by counting tool lines and mtime

(`rg -c '^\[tool\]' run.log`, `stat -f '%Sm' run.log`). `--format quiet` prints only

the final text (plus an `[acpx] tokens:` line on stderr) - no `[tool]`, no `[done]` -

so those counts read 0; supervise quiet runs by exit code, result file, and the one

stderr line `[acpx] error: <CODE> [<DETAIL_CODE>] <message>` on failure. `exec` saves

nothing to watch; for codex, `tail -f` the newest

`~/.codex/sessions/<date>/rollout-*.jsonl` (written even for `exec`).

## Teardown

`sessions close <n>` takes down the whole resident stack (owner -> `npm exec` ->

`node <adapter>` -> agent binary -> its MCP servers) and marks the task finished.

With chained one-shot dispatch the close runs itself; a separate close is owed only

after a failed turn's recovery or a deliberately tended multi-turn session - there

the idle TTL frees only the process stack, and the record stays open until you close

it. A `"ttl": 0` config makes forgotten owners resident for hours; with the default

they exit after 300s idle.

Liveness and leak check - never `pgrep -l` or `ps -o args`: command lines of wrapper

shells can carry secrets, and the bracketed first letter keeps the pattern from

matching the shell that runs it (Linux `pgrep` matches its ancestors):

```bash

PAT='[a]cpx.*__queue-owner|[c]odex-acp|[c]laude-agent-acp|[a]gy_acp_server|[l]ocalharness_external'

pgrep -f "$PAT" | wc -l # 0 once your runs are closed

P=$(pgrep -d, -f "$PAT") && ps -o pid,ppid,etime,rss,comm -p "$P" # no args column

```

- `close` returns before `npm exec` / `node` exit - poll for ~10s before calling

anything a straggler. Other people's runs count too; scope with

`lsof -a -d cwd -Fn -p <pid>` (adapter and agent run in `--cwd`).

- **A straggler gets a plain `kill <owner pid>`**; SIGTERM takes the stack down within

seconds. Since 0.19 even SIGKILL no longer strands the adapter (it exits on stdin

EOF), but a mid-turn kill loses the turn: `Queue owner disconnected before prompt

completion; outcome unknown`.

- **Owners lingering with no `--ttl 0` on the command line**: run

`acpx --cwd <dir> config show` - a `ttl` key in `~/.acpx/config.json` or the

project's `.acpxrc.json` sets the default idle TTL, and `"ttl": 0` disables the

self-reap for every invocation it covers.

- **Close owners started by an older acpx before upgrading** - 0.19 refuses forced

retirement of legacy owners it cannot verify (`QUEUE_SHARED_RUNTIME_UNSUPPORTED`:

wait for idle expiry or close).

- Closed records persist indefinitely; `sessions prune --older-than 7

## MCP

`--mcp-config <path>` **replaces** the project/global `mcpServers` for that invocation.

The file path resolves against `--cwd` (the last `--cwd` / `--mcp-config` wins); paths

*inside* the file are passed verbatim. The shipped reference does not mention it.

**The file shape is not the standard one.** acpx wants a JSON *array* of named server

objects; the standard object-keyed map fails with

`Invalid mcpServers in <path>: expected array` (exit 1). `env` and `headers` are

arrays of `{name, value}` too; a missing `type` means stdio.

```jsonc

// RIGHT - an array, each entry carrying its own name

{ "mcpServers": [ { "name": "example", "type": "stdio", "command": "example", "args": ["mcp"],

"env": [ { "name": "LOG_LEVEL", "value": "info" } ] } ] }

```

**A stdio server that dies only under agy is an MCP era mismatch, not an acpx fault.**

agy probes stdio with `server/discover` (MCP 2026-07-28 retired the `initialize`

handshake); a legacy server that *aborts* on the unexpected request kills the pipe

instead of answering an error, leaving nothing to fall back from. The codex and claude

adapters do not probe, which is the only reason the same config works for them. Fix

the server (answer an error, or move to a current MCP SDK), or reach it over HTTP.

The turn still exits **0** and ends `[done] end_turn` - grep for

`failed to initialize` before trusting any agy run that used MCP.

- **A live queue owner refuses a config change** (it carries the config path plus a

SHA-256 fingerprint): `sessions close` first.

- **`--mcp-config` replaces the whole set** - verify a config written for one adapter

on another with a one-shot `exec` that asks the agent to name its own tools.

- acpx does no `${...}` expansion; whatever the agent expands resolves in the

environment it inherited from the **launcher**, so a variable like a session id

resolves to *your* id. Never let an identity flow in through the environment.

## Limits

- **Incoming ACP messages cap at 64 MiB** since 0.15.1 (previously unlimited);

`ACPX_MAX_ACP_MESSAGE_BYTES` raises it, `0` disables.

- Terminal output retention defaults to 64 KiB per call when the agent sets no limit;

`ACPX_TERMINAL_MAX_OUTPUT_BYTES` is a host ceiling that can only lower it.

- Long unattended work: `--timeout 5400`, plus a wrapping shell `timeout` with a

uncommitted work in the cwd - a relaunch prompt should say so. Do NOT add

`--ttl 0` - the 300s default covers any gap within one run, and `--ttl 0` removes

the only automatic reaper (invariant 6). Reserve it for a human-driven warm session

you will close by hand.

- `--format quiet` for fleets you judge by exit code and result file;

`--suppress-reads` on every long run.

- Headless permission requests nobody can answer are denied; a turn where none was

approved and at least one was denied exits **5**. `--non-interactive-permissions fail` stops at the first

one instead (`Permission prompt unavailable in non-interactive mode`).

- Pass long briefs as `-f <path>` or a path in the prompt, never inlined - inlined

content in a shell command is what a driving harness's classifier blocks on.

## Talking to a live session

For the one live turn of a one-shot dispatch, and for recovery after a failed one.

Verified end to end with acpx 0.19.4 and claude-agent-acp 0.85.1:

- **Queue:** `--no-wait` prompts run in submission order after the running turn.

- **Redirect:** `cancel -s <name>`, then a new prompt. Nothing reaches a running turn

otherwise (see below).

- **Blockers:** have the brief tell the agent to stop with `BLOCKED: <what, where>` at

the top of its result file - and dump everything gathered so far below it - then end

the turn. Close the session and answer with a fresh one fed the brief plus that

file: the blocking state lives outside the conversation (creds are machine-level,

results belong in files), and a resumed child's memory is not what you assume (a

failed reconnect silently starts a new conversation - see Recovery).

- **Mid-turn channel:** when a brief may need an answer mid-turn, tell the agent to

append `PROGRESS:` / `QUESTION:` lines to a progress file and to poll an answer file

with short foreground sleeps. Tail the progress file from the driving side (under

the Monitor tool from Claude Code) and write the answer file. A blocker answered

- **Recovery:** a failed or timed-out turn (exit 3, `turn_result: failed`) leaves the

session intact - prompt the same name again. After the idle owner exits, the next

prompt respawns and resumes the same conversation. After any respawn check that

`sessionId` in `sessions show` is unchanged: a failed reconnect silently falls back

to a new conversation. After recovery the close is yours to run - the chain already

skipped it.

## What acpx cannot do

Structural, not bugs. Do not design around them.

- **An ACP session does not wake.** An externally injected message lands in the

transcript but starts no turn; the only inbound channel is acpx itself

(`-s <name>`, optionally `--no-wait`), plus a file the brief told the agent to poll.

- **`codex queue --thread` does not reach an acpx-driven codex session** (it does wake

a plain interactive codex).

- **acpx-spawned Claude sessions bind no IPC socket**, so `ListAgents` /

`SendMessage` cannot see or reach them.

- **acpx cannot attach to a live process it did not start** (`--resume-session` loads

a saved ACP session into a new adapter; see Sessions).

## Failures

Exit codes (absent from the shipped reference; repo `docs/exit-codes.md` has them):

| code | meaning |

|---|---|

| 0 | success (also `cancel` with nothing to cancel) |

| 1 | agent / protocol / runtime error - the catch-all; also a global flag after the agent |

| 3 | `--timeout` exceeded |

| 4 | no session found by the directory walk |

| 5 | permission denied in this turn (none approved, one denied/cancelled); `--non-interactive-permissions fail`; agy user-answer questions |

| 130 | interrupted - racy: a SIGINT the cooperative cancel settles first exits 0 with `[done] cancelled` |

Error catalog - string -> fix:

- `⚠ No acpx session found (searched up to <dir>)` (exit 4) - invariant 2:

`sessions ensure --name <n>` first; confirm `--cwd` is inside the same repo boundary.

- `No named session "<n>" for cwd <cwd> and agent <agent>` (exit 1) - `sessions

close|show` with a wrong name or cwd; `sessions list --local`.

- `error: unknown option '--cwd'` (exit 1) - global flag after the subcommand

(invariant 1).

- `Do not combine positional agent with --agent override` (exit 2) - drop the

positional `claude`/`codex`.

- `Agent command must not be empty` (exit 2) - an empty `--agent` (unset variable).

- `Failed to spawn agent command: agy_acp_server.par` (exit 1) - built-in

`antigravity` with the `.par` off PATH; see agy.

- `Invalid mcpServers in <path>: expected array` (exit 1) - see MCP.

- `MCP config file not found: <path>` (exit 1) - a relative `--mcp-config` resolves

against `--cwd`.

- `Cannot apply --model "<id>": the ACP agent did not advertise that model. Available

models: ...` (exit 1, any agent) - pick from that list; codex: or pin a newer adapter.

- `Invalid value for config option model: <id> (ACP -32603, adapter reported

"Internal error")` - `set model` with no match in the advertised list; use `--model`

at session creation (see claude).

- `RUNTIME: Model '<id>' not found` - `--model` typo or an id the harness lacks; a 404

mid-turn reads `There's an issue with the selected model (<id>)`.

- `Claude Code 2.1.2xx does not support this model` - adapter too old; pin a newer one

(see claude).

- `Internal error` from `claude set reasoning_effort` - claude's knob is `set effort`.

- agy stalls at `[client] session/new (running)` until timeout (exit 3) - `auth.type`

set but never signed in; sign in once interactively.

- `502 Bad Gateway: Failed to connect to backend API` (agy, exit 0) - missing CA

bundle on NixOS; see Linux / NixOS.

- `Antigravity requested a user answer...` (exit 5) - agy asked a fixed-choice

question; rewrite the brief so it never needs one.

- `The MCP server '<name>' failed to initialize` (agy, exit 0) - see MCP.

- `RUNTIME: This client is no longer supported for Gemini Code Assist`, or `Gemini CLI

ACP startup timed out before initialize completed` - you used the built-in `gemini`

agent; use agy.

- `already has an active writer (code -32600)` - `codex resume` while acpx still owns

the thread; `sessions close <n>` first.

- `Queue owner disconnected before prompt completion; outcome unknown` (exit 1) - the

owner died mid-turn, or dropped a slow reader (full output spool) while the prompt

kept running; check `sessions history` and the cwd before resubmitting.

- `Missing --skill action.` (exit 1) - `--skill` needs

`show|list|install|export|help`.

- `error: unknown option '--one-shot'` - not a verb (exit 1 after the agent, 2

before); `exec` is the one-shot form.

- `Timed out after <ms>ms` (exit 3) - the wall clock ran out, not a stuck agent -

check `sessions show` for `lastActivity`; an adapter-side timeout surfaces as exit 1

instead.

Silent failures worth an explicit check: content-filter kills and MCP load failures

both end `[done] end_turn` with exit 0; a denied agy write ends `[done] end_turn`

with exit 5; a `--no-wait` prompt that "sent" may still be queued behind a running

turn; `status` reads `running` long after completion; `sessions close` drops pending

`--no-wait` prompts with no error and cancels the active turn, whose submitter exits

0 with `[done] cancelled`; killing a blocking submitter kills the child's turn with

it (SIGTERM: exit 143, nothing reaches the transcript); and a `completed`

`turn_result` does not prove provider success - a codex provider error can end as a

clean `end_turn` (openclaw/acpx#850) - the result file remains the check.