GitHub Actions

Automate your workflows with mux run in GitHub Actions

mux run is designed for automation scenarios like CI/CD pipelines. This guide shows how to integrate mux into your GitHub Actions workflows.

Prerequisites

1. API Key: Add your ANTHROPIC_API_KEY (or other provider key) to your repository’s secrets. See Providers for details on configuring API keys.
2. npm/bun: The workflow will install Mux via bunx or npx

Basic Usage

Here’s a minimal example that runs Mux in a GitHub Action:

- name: Mux Review
  env:
    ANTHROPIC_API_KEY: ${{ secrets.ANTHROPIC_API_KEY }}
    GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
  run: bunx mux run "Review this PR for critical issues. If any are found, exit with 1 to block merge."

mux run supports agent-controlled exit codes, so the workflow step can fail when issues are found.

Key Options for CI

Option	Purpose
--quiet	Only output final result (cleaner logs)
--json	Machine-readable NDJSON output for parsing
--budget <usd>	Limit spending per run (e.g., --budget 1.00)

Example: Auto-Cleanup Workflow

This is the exact workflow used live in the Mux repo (see .github/workflows/auto-cleanup.yml). It runs periodically to identify low-risk cleanup opportunities and maintains a refactor PR with improvements.

The prompt is stored in a separate file (.github/prompts/auto-cleanup.md) and piped via stdin, keeping the workflow file clean and the prompt easy to iterate on.

Mux’s repo uses a workflow-specific repository secret (AUTO_CLEANUP_ANTHROPIC_API_KEY) for this job so auto-cleanup spend stays isolated from terminal-bench, while the runtime environment still uses the standard ANTHROPIC_API_KEY name.

# Periodically cleans up the codebase and maintains a refactor PR.
# SETUP: Add AUTO_CLEANUP_ANTHROPIC_API_KEY, MUX_APP_PRIVATE_KEY, and MUX_APP_ID
# to repository secrets so auto-cleanup spend stays isolated from terminal-bench.

name: Auto-Cleanup

on:
  schedule:
    - cron: "0 */4 * * *" # Every 4 hours
  workflow_dispatch:

permissions:
  contents: write
  pull-requests: write

jobs:
  cleanup:
    runs-on: ubuntu-latest
    steps:
      - name: Check required secrets
        id: precheck
        env:
          # Keep the runtime env name stable while routing spend to a dedicated key.
          ANTHROPIC_API_KEY: ${{ secrets.AUTO_CLEANUP_ANTHROPIC_API_KEY }}
          MUX_APP_ID: ${{ secrets.MUX_APP_ID }}
          MUX_APP_PRIVATE_KEY: ${{ secrets.MUX_APP_PRIVATE_KEY }}
        run: |
          missing=0
          [ -z "$ANTHROPIC_API_KEY" ] && echo "Skipping (missing AUTO_CLEANUP_ANTHROPIC_API_KEY)." && missing=1
          [ -z "$MUX_APP_ID" ] && echo "Skipping (missing MUX_APP_ID)." && missing=1
          [ -z "$MUX_APP_PRIVATE_KEY" ] && echo "Skipping (missing MUX_APP_PRIVATE_KEY)." && missing=1

          if [ "$missing" -eq 1 ]; then
            echo "enabled=false" >> "$GITHUB_OUTPUT"
          else
            echo "enabled=true" >> "$GITHUB_OUTPUT"
          fi

      - uses: actions/create-github-app-token@d72941d797fd3113feb6b93fd0dec494b13a2547 # v1.12.0
        id: app-token
        if: ${{ steps.precheck.outputs.enabled == 'true' }}
        with:
          # Use a GitHub App token so PR events trigger CI. PRs opened via
          # GITHUB_TOKEN intentionally do not trigger other workflows.
          app-id: ${{ secrets.MUX_APP_ID }}
          private-key: ${{ secrets.MUX_APP_PRIVATE_KEY }}

      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
        if: ${{ steps.precheck.outputs.enabled == 'true' }}
        with:
          fetch-depth: 0
          token: ${{ steps.app-token.outputs.token }}
      - uses: oven-sh/setup-bun@b7a1c7ccf290d58743029c4f6903da283811b979 # v2.1.0
        if: ${{ steps.precheck.outputs.enabled == 'true' }}
        with:
          bun-version: 1.3.5

      # Pin the git identity so the AI agent doesn't invent its own.
      # Without this, commits end up as "mux-auto-cleanup[bot]" while the
      # PR itself (created via the app token) is authored by "mux-bot[bot]".
      - name: Configure git identity
        if: ${{ steps.precheck.outputs.enabled == 'true' }}
        run: |
          git config user.name "mux-bot[bot]"
          git config user.email "264182336+mux-bot[bot]@users.noreply.github.com"

      - name: Cleanup with mux
        if: ${{ steps.precheck.outputs.enabled == 'true' }}
        env:
          ANTHROPIC_API_KEY: ${{ secrets.AUTO_CLEANUP_ANTHROPIC_API_KEY }}
          GH_TOKEN: ${{ steps.app-token.outputs.token }}
        run: |
          bunx mux@next run \
            --model anthropic:claude-opus-4-7 \
            --thinking xhigh \
            < .github/prompts/auto-cleanup.md

CLI Reference

Full CLI documentation

Agentic Git Identity

Configure separate Git identity for AI commits