# ADR 0004: Media behind an S3-like interface

- Status: accepted
- Date: 2026-09

## Context
Attachments (images, files, videos) need storage, thumbnails for images, and
bounded upload size. Storage must survive container restarts and, ideally, be
swappable without touching API code.

## Decision
Define a `Storage` interface (`Save`/`Open`/`Delete` keyed by opaque keys) in
`internal/media`. Phase 2 ships `Local` — files on disk with atomic
temp-file+rename writes and path-traversal protection. API handlers depend
only on the interface.

## Consequences
- Metadata lives in Postgres (`media` table); bytes live in storage.
- Replacing disk with MinIO/S3 means a new `Storage` implementation, no
  handler changes.
- Image thumbnails are generated with stdlib decoding + `x/image/draw`,
  avoiding CGO and external binaries.