Use this section for exact application, command, configuration, compatibility, and diagnostic contracts.
- API reference — a context-at-a-glance map plus the exact Router, request, header, route parameter, state, response, and capability surfaces.
- Provider and target compatibility — supported behavior across Node and Fastly Native and JavaScript targets.
- Managed handler TypeScript and JavaScript — the accepted authoring language and Native eligibility boundary.
- CLI reference — commands, flags, and machine-readable command specification.
- Native build optimization — the default recipe, shrink0 fallback, experimental selections and optional json-as arena setting.
- Project configuration — profiles, providers, targets, bindings, and schemas.
- Diagnostics and remediation — stable public diagnostic codes and corrective actions.
- Environment variables — supported tooling inputs and contributor-only controls.
- Shell completion — Bash, Zsh, and Fish integration.
Repository governance, release operations, publication, deployment, and evidence procedures are intentionally separated from the application reference. Maintainers can enter that narrower surface through the maintainer documentation.