Python dev server

Play includes a small Python HTTP server for local development:

python tools/dev_server.py --root . --port 8000

What it does

  • Serves static files under --root.

  • Ensures correct MIME types for: - .mjs / .js → JavaScript - .wasm → application/wasm

  • Adds security/cache headers: - X-Content-Type-Options: nosniff - Cache-Control: dev-friendly defaults

  • For .mjs/.js/.wasm, it forces Cache-Control: no-store and disables conditional caching (to avoid stale modules/WASM and confusing 304s). This is deliberate for local development, but it will make reloads and model switching slower than a production/static host.

  • Mounts stable prefixes: - /mujoco-wasm-play/ → repo root - /forge/ → sibling forge repo if present (otherwise falls back to the

    Play repo root)

    • /mujoco-wasm-forge/ → legacy alias for a sibling forge repo

Environment variables

  • PLAY_DEV_SERVER_DEBUG_MOUNTS=1: prints mount/path debug logs to stderr.

Source of truth

See tools/dev_server.py.