# Adapter Contract

This document defines the runtime contract every EDC adapter must implement against the v2 context layout.

## Shared Inputs

- `AGENTS.md` or referenced `EDC_AGENTS.md`: short startup orientation for humans and runtimes.
- `edc-context/index.md`: routing-first operational index loaded at session start or on demand; use it for path/task guidance, critical invariants, coupling/blast radius, compact architecture, and report links.
- `edc-context/manifest.json`: authoritative routing and policy contract.
- `edc-context/modules/<name>.md`: deep per-module context selected by manifest routing.

## Advisory Mode

- The adapter MAY surface the EDC agent entrypoint (`AGENTS.md`, or `EDC_AGENTS.md` when referenced) and `edc-context/index.md`, but MUST NOT auto-inject module docs on tool use.
- Review/build entrypoints still use `edc-context/manifest.json` as the source of truth for report paths and freshness checks.
- Missing hook support is acceptable because advisory mode is documentation-only.
- Failure mode: if advisory is requested but the adapter cannot even expose the docs, it must fail loudly.

## Inject Mode

- The adapter MUST discover `edc-context/manifest.json` before guarded operations.
- Session-start behavior loads `edc-context/index.md`.
- Pre-tool behavior resolves the target file through the shared router and injects `edc-context/modules/<name>.md`.
- If manifest routing is missing, stale, ambiguous, or points to a missing module doc, the adapter must fail loudly or surface a warning instead of silently injecting the wrong file.

## Routing Rules

- Adapters MUST treat `edc-context/manifest.json` as the only routing contract.
- Target file resolution uses the shared JS classifier (`plugins/edc/hooks/lib/classify-cli.mjs` / `route.mjs`).
- Ambiguous matches are hard failures.
- Unmatched files follow `policy.unmatchedPathPolicy`.

## Mode-Specific Failure Surface

- `advisory`: best-effort docs only, no hook registration.
- `inject`: hook/runtime registration required; missing hook plumbing is an implementation bug.
- Unimplemented agent/mode pairs MUST exit with `edc: <agent>/<mode> not yet implemented`.