docs: AGENTS.md notes per-feature manifest contract

AGENTS.md

@@ -366,6 +366,22 @@ Each feature binder signature is `(ctx: BindProductionContext): void` for produc
 
 ---
 
+### Conformance contract (every feature)
+
+Every feature package MUST declare a `src/feature.manifest.ts` using `defineFeature` from `@repo/core-shared/conformance`. The manifest declares the use cases, what they audit/publish/consume, and which optional cores they require.
+
+The feature's `src/di/bind-production.ts` MUST call `assertFeatureConformance(container, manifest, symbols, ctx)` at the tail of `bindProduction<Name>` so `pnpm dev` refuses to boot if a binding loses its brand.
+
+Re-export the manifest from `src/index.ts`:
+
+```ts
+export { fooManifest, type FooManifest } from "./feature.manifest";
+```
+
+See `docs/guides/conformance-quickref.md` for the canonical pattern; the generator (`pnpm turbo gen feature <name>`) emits all of this correctly by default.
+
+---
+
 ### Cross-feature events and background jobs (Plan 10, ADR-015)
 
 Three rules: