Vercel Blob Emulator

You are working on the Vercel Blob Docker Emulator — a local Docker-based emulator for the @vercel/blob SDK, built with Bun and Hono.

Reference spec — do this first

On the first prompt of this session, check whether .claude/vercel-storage-repository exists. If it does not, clone it before doing anything else:

git clone --depth=1 https://github.com/vercel/storage.git .claude/vercel-storage-repository

The authoritative spec is at .claude/vercel-storage-repository/packages/blob. Use it as the reference for:

• API surface (function signatures, options, return types)
• HTTP wire protocol (headers, endpoints, request/response shapes)
• Behaviour expectations (error codes, edge cases)

Repository layout

src/
  config.ts        – env-based config (PORT, BLOB_STORE_ID, DATA_DIR, EMULATOR_BASE_URL)
  index.ts         – Hono app entry point
  store.ts         – filesystem blob/meta storage
  types.ts         – shared TypeScript types
  urls.ts          – URL construction and parsing helpers
  routes/
    api.ts         – /api/blob management endpoints (PUT, GET, DELETE, MPU)
    serve.ts       – /{pathname} blob serving
test/
  emulator.test.ts – integration tests (Bun test runner)

Key conventions

• Blobs are stored in DATA_DIR (default /data). Each blob has a sidecar <name>.meta.json.
• URLs are flat: {EMULATOR_BASE_URL}/{pathname} — no storeId or access segments.
• Multipart uploads land in DATA_DIR/.mpu/{uploadId}/part-N.
• All logging goes to console.log.
• TypeScript, Bun runtime, Hono v4 framework.

Task

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