Peer

Peer asks Fable 5 to review a Codex prompt before the turn runs, then injects the amended brief as hidden additional context. Fable oversees; Codex executes.

The hook is opt-in per prompt. Start a prompt with [peer] or include [peer] in the prompt to activate review for that turn. Prompts without [peer] are passed through unchanged and do not call Fable.

It does not replace the submitted prompt because Codex hook output does not currently support direct prompt replacement. It uses the supported UserPromptSubmit additionalContext path.

How Fable is called

Peer talks to Fable through the Claude Code CLI in headless mode (claude -p) by default:

• Subscription auth — uses your existing claude login (OAuth), no ANTHROPIC_API_KEY needed.
• Persistent reviewer session — the first [peer] review creates a Claude session; later reviews in the same Codex thread --resume it, so Fable keeps the goal and everything it already learned instead of starting fresh each time. Session ids and review history are stored under $CODEX_HOME/peer/sessions/ (default ~/.codex/peer/sessions/).
• Structurally read-only — the child gets --tools Read,Glob,Grep,LS,WebSearch,WebFetch only (no Bash, no write/edit tools), --permission-mode dontAsk, --setting-sources user, --strict-mcp-config, and hooks disabled, so a hostile workspace cannot expand its permissions. Git state (branch, status, recent commits, diffstat) is collected by the hook with a sanitized environment and injected into the prompt instead.
• Structured output — the review comes back through --json-schema, so there is no retry protocol around a required tool call.
• No key leakage — ANTHROPIC_API_KEY/ANTHROPIC_AUTH_TOKEN and NODE_OPTIONS are stripped from the child environment, so reviews bill your subscription, never a stray API key. .env files are read with an allowlist: only PEER_* keys and ANTHROPIC_API_KEY are imported.

If the claude CLI is not installed and ANTHROPIC_API_KEY is set, Peer falls back to the legacy @just-every/ensemble API backend.

Configuration

Optional environment variables (environment, project .env, plugin .env, or ~/.env):

PEER_DISABLED=1              # turn the hook off
PEER_BACKEND=auto            # auto (default) | claude | ensemble
PEER_CLAUDE_BIN=claude       # path to the Claude Code CLI
PEER_MODEL=claude-fable-5    # model passed to the backend
PEER_EFFORT=                 # optional --effort for the claude backend (low..max)
PEER_TIMEOUT_MS=1200000      # per-review timeout (20 minutes)
PEER_MAX_CONTEXT_CHARS=12000 # cap on conversation context sent with the prompt

ANTHROPIC_API_KEY is only required for the ensemble backend.

CLI

node scripts/peer.js "Implement this feature, but check the tests first."

JSON:

printf '%s\n' '{"prompt":"Review this request","cwd":"/path/to/repo"}' | node scripts/peer.js

CLI invocations from the same cwd resume the same reviewer session.

Hooks

hooks/hooks.json registers a UserPromptSubmit command hook. The hook is a no-op unless the submitted prompt contains [peer]. Plugin installation and hook trust are handled by Codex; this repository does not install or trust hooks automatically.

Development

npm test