Agentic Control Plane for Meta Muse Code

Policy-check every tool call Muse Code makes — before it runs — against your Agentic Control Plane workspace: allow / ask / deny per call, output scanning after the call, one receipt line per session, every decision in your activity log with the reason attached.

Status: beta-tracking-beta, contract verified

Muse Code is in beta, and in the 0.2.1 binary hooks ship as plugin capabilities behind the MUSE_EXPERIMENTAL_PLUGINS flag (the flag gates only the management CLI — installed hooks fire in normal runs). The wire contract is Claude Code's hook schema, verified end-to-end against Muse's own muse plugins hook test runner: snake_case payloads in (hook_event_name, tool_name, tool_input, session_id, permission_mode), camelCase hookSpecificOutput decisions back, exit 2 + stderr as the fallback block channel, systemMessage for advisory lines. Two things still await a live model run (the offline echo provider makes no tool calls): the ask-prompt round trip in an interactive session, and the live PreToolUse payload — its session-level siblings are already confirmed byte-compatible.

Install

This package is a Muse native plugin bundle (.muse-plugin/plugin.json at the package root):

npm install -g @agenticcontrolplane/muse-code
MUSE_EXPERIMENTAL_PLUGINS=1 muse plugins install "$(npm root -g)/@agenticcontrolplane/muse-code" --scope user
MUSE_EXPERIMENTAL_PLUGINS=1 muse plugins approve acp

Sign in once to get a credential:

• a key in ~/.acp/credentials (written by the installer — one command, free for individuals).

Muse Code runs hooks with a cleared environment, so ACP_BEARER_TOKEN does not reach them in live sessions — the file is the real path. Optional operational overrides live in ~/.acp/config.json: govern_base, console_base, agent_tier, check_timeout_ms, shadow.

What it does

Event	Gateway call	Effect
PreToolUse	POST /govern/tool-use	allow / ask / deny before the tool runs
PermissionRequest	POST /govern/tool-use	a policy deny settles Muse's own approval; anything else lets the native prompt proceed
PostToolUse	POST /govern/tool-output	output scanning; a server block becomes a deny the model sees
Stop	—	one session receipt line with a deep link to the session timeline

Failure posture

An unreachable control plane must never brick your session, and must never be mistaken for a live one:

• Interactive sessions fail open, loudly — the call proceeds, you get an [ACP] ⚠ UNGOVERNED warning, and a lapse line lands in ~/.acp/lapse.log.
• Unattended tiers fail closed — CI/MUSE_HEADLESS/ACP_AGENT_TIER mark a run as unattended, and a run nobody is watching stays blocked when policy can't be consulted.
• Policy denies are unaffected either way; the posture only covers the inability to ask the policy.

Security notes

• Muse Code executes hooks outside its own sandbox, with a cleared environment. That is exactly why this hook has zero dependencies and no build step: every transitive dependency on a control-plane hook is a credential-adjacent supply-chain target. It is one file of plain ESM you can read in two minutes.
• managed_hooks_path hooks run with no trust step. If you deploy this hook through that channel, the managed file's write access is your control boundary — treat it like sudoers.

Test

npm test

Offline suite against a mock gateway: decision mapping, both fail postures, retry-once transport behavior, payload shape, receipt.