---
package: reflect-metadata
version: "^0.2.2"
tier: feature
decision: approved
date: 2026-05-14
deciders: [Danijel Martinek]
adr: adr-002
lastRevalidated: null
is-sub-processor: false
processes-pii: false
filter-results:
  license: Apache-2.0
  types: native
  maintenance: dormant
  boundary-fit: pass
  shadow-check: pass
  eu-residency: n/a
  cve-scan: clean
  named-consumer: pass
  socketRisk: clean
verification-commands:
  - npm view reflect-metadata license
  - npm view reflect-metadata version
  - pnpm audit --audit-level=moderate
accepted-cves: []
---

## Filter: license

<!-- Result: Apache-2.0 -->

`npm view reflect-metadata license` returns `Apache-2.0`. Apache-2.0 is on the allowlist.

## Filter: types

<!-- Result: native -->

reflect-metadata ships its own `.d.ts` declaration files. Types are bundled with the package.

## Filter: maintenance

<!-- Result: dormant -->

reflect-metadata implements the TC39 Metadata Reflection API proposal polyfill. The library is intentionally stable; new releases are rare because the spec is frozen pending TC39 progress. `dormant` is the accurate classification for a finished polyfill — this is not a concern for a library at this maturity level.

## Filter: boundary-fit

<!-- Result: pass -->

reflect-metadata is a required peer of InversifyJS (ADR-002). Feature packages importing inversify are expected to also import `reflect-metadata` once at the entry point of each feature's DI layer. No boundary rule restricts it.

## Filter: shadow-check

<!-- Result: pass -->

reflect-metadata is the only metadata polyfill in the workspace. It is explicitly paired with inversify per ADR-002 and has no competing alternative present.

## Filter: eu-residency

<!-- Result: n/a -->

reflect-metadata is a pure runtime polyfill with no network communication, telemetry, or data transmission. EU residency does not apply.

## Filter: cve-scan

<!-- Result: clean -->

`pnpm audit --audit-level=moderate` reports no advisories against reflect-metadata at the time of this trace.

## Filter: named-consumer

<!-- Result: pass -->

All five feature packages — `@repo/auth`, `@repo/blog`, `@repo/media`, `@repo/marketing-pages`, `@repo/navigation` — list reflect-metadata as a runtime dependency. It is imported at each feature's DI entry point to activate the metadata polyfill required by inversify decorators.

## Prompt: replaces

No prior metadata polyfill was in use. reflect-metadata is a direct requirement of InversifyJS's decorator-based binding — there is no alternative polyfill to retire.

## Prompt: migration-cost-out

Mechanical, but coupled to inversify removal. If InversifyJS is ever replaced with a DI approach that does not rely on the Reflect API (e.g., a factory-only approach), reflect-metadata can be removed by deleting one import per feature entry point. The removal is straightforward once the parent dependency (inversify) is gone.

## Prompt: alternatives-considered

1. **No polyfill / TC39 native** — The TC39 Metadata Reflection API is not yet at Stage 4; native support is not available in target runtimes. Not viable.
2. **`core-js` reflect subset** — Does not provide the complete `Reflect.metadata` API surface required by inversify. Not a functional alternative.
