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+---
+id: 01-define-feature-helper
+epic: conformance-system-v1
+title: defineFeature helper + Instrumented/Captured/Audited brands
+type: technical-story
+status: in-progress
+feature: core-shared
+depends-on: []
+blocks: [02-boot-assertions]
+---
+
+## Goal
+Manifest helper + brand types enable type-level enforcement that every
+use-case binding is wrapped with `withSpan` + `withCapture`
+(and `withAudit` when mutating with audits declared).
+
+## Why
+Compile-time feedback is the cheapest layer and the foundation every other
+milestone reads.
+
+## Done when
+Compile-time TS2322 fires when an unwrapped factory is bound through
+`ProductionUseCase<...>`, and `auth.signIn` is rebound through the new slot.
+
+## In scope
+- `Instrumented<F>` and `Captured<F>` brand types in `@repo/core-shared/conformance`
+- Brand attachment in `withSpan` and `withCapture`
+- `Audited<F>` brand and `withAudit` wrapper in `@repo/core-audit`
+- `defineFeature` helper + `FeatureManifest` / `UseCaseManifest` types
+- `ProductionUseCase<I, O, M>` branded slot type
+- `authManifest` declaring `signIn`, `signUp`, `signOut`
+- `auth.signIn` rebound through the branded slot
+
+## Out of scope
+- `auth.signUp` / `auth.signOut` rebinding through branded slots (separate tasks within this story or a follow-up story; signUp requires `Audited<F>` once we declare its `audits`)
+- Boot-time `assertConformance` (story 02)
+- ESLint rules reading the manifest (story 03)
+- Generator emitting manifest stubs (story 05)
+
+## Tasks
+- [ ] Brand types: `Instrumented<F>` and `Captured<F>`
+- [ ] `withSpan` attaches `Instrumented`
+- [ ] `withCapture` attaches `Captured`
+- [ ] `defineFeature` helper + manifest types
+- [ ] `ProductionUseCase<I, O, M>` slot type
+- [ ] `withAudit` wrapper + `Audited` brand
+- [ ] `authManifest` declaration
+- [ ] `auth.signIn` rebound through branded slot
+- [ ] Negative test: unwrapped factory rejected at type level