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`amber watch`

Run from: the generated application root beside shard.yml.

amber watch

The default V2 watch configuration rebuilds when Crystal source, environment YAML, ECR views, or authored assets change. It builds assets first, creates bin/, builds the app target, runs it, and restarts after matching files change.

watch:
  run:
    build_commands:
      - mkdir -p bin
      - crystal build ./src/my_app.cr -o bin/my_app
    run_commands:
      - bin/my_app
    include:
      - ./config/**/*.cr
      - ./config/environments/*.yml
      - ./src/**/*.cr
      - ./src/**/*.ecr
      - ./app/assets/**/*

Use environment variables normally:

AMBER_SERVER_PORT=8080 amber watch

Stop the watcher with Ctrl-C. If a rebuild fails, run the printed build command directly to get the complete compiler error.

Asset-aware watch cycle

CLI 2.0.6 runs the same build-time compiler as amber assets build before application compilation. A deleted asset, missing CSS image/font reference, missing local JavaScript dependency, or invalid manifest entry therefore stops the rebuild instead of becoming a browser 404.