/storage

name: storage
description: Use when uploading or downloading files, generating presigned URLs, configuring storage ACLs, or persisting file references (avatars, attachments, images) in a Butterbase app

Butterbase Storage

Butterbase stores files in S3 (or LocalStack in dev) and exposes them via presigned URLs. Every file gets a stable `object_id` (UUID) that you persist in your tables; URLs are generated on demand and expire.

All storage operations go through one tool: **`manage_storage`** with an `action` parameter.

| Action | Purpose | |--------|---------| | `upload_url` | Generate a 15-minute presigned PUT URL and reserve an `object_id` | | `download_url` | Generate a 1-hour presigned GET URL for a stored object | | `list` | List objects (scoped by caller's role) | | `delete` | Permanently remove an object from S3 + database | | `update_config` | Toggle app-level `publicReadEnabled` and other storage settings |

---

1. The mental model: `object_id` vs `s3_key`

| Field | What it is | When you use it | |-------|-----------|-----------------| | `object_id` | UUID, stable, app-level handle | Persist in your tables (e.g. `users.avatar_id`, `posts.image_id`) | | `s3_key` | Internal bucket path like `app_abc/user_uuid/file.jpg` | Internal only — **never** treat this as a URL |

**Critical:** `s3_key` is **not** a URL. You cannot use it as `<img src>` or `<a href>`. Always store the `object_id` and resolve a fresh download URL at render time.

---

2. The upload lifecycle

A single upload is two HTTP calls and one DB insert in your app:

┌─────────────────────────┐
│ 1. manage_storage(      │  → returns { upload_url, object_id, expires_at }
│      action: upload_url)│
├─────────────────────────┤
│ 2. PUT file -> S3       │  → must include exact Content-Type header
├─────────────────────────┤
│ 3. INSERT INTO ...      │  → save object_id alongside the user/post/etc.
└─────────────────────────┘

If you skip step 3, the file lives in S3 but no row references it — an **orphaned object** counting against your quota. Always persist the `object_id`.

Step 1 — request an upload URL

manage_storage({
  app_id: "app_abc123",
  action: "upload_url",
  filename: "avatar.jpg",
  content_type: "image/jpeg",
  size_bytes: 245123,
  public: false                  // optional; default false
})

Returns:

{
  "upload_url": "https://s3.amazonaws.com/...",
  "object_id": "9c14b2e0-...",
  "expires_at": "2026-05-08T22:15:00Z"
}

The `object_id` is created **immediately** in the database; the file just hasn't been uploaded yet.

Step 2 — PUT the bytes

The Content-Type on the PUT must match exactly the `content_type` you sent in step 1. If it doesn't, S3 rejects the upload or stores the wrong MIME — breaking browser previews.

curl -X PUT "{upload_url}" \
  -H "Content-Type: image/jpeg" \
  --data-binary @avatar.jpg

From the browser:

await fetch(uploadUrl, {
  method: "PUT",
  headers: { "Content-Type": file.type },
  body: file
});

Step 3 — persist the `object_id`

UPDATE users SET avatar_id = $1 WHERE id = $2

Or via the auto-API / SDK — whatever your app uses for writes. Without this step, the file is unreachable.

---

3. Generating download URLs

Each call returns a fresh URL valid for 1 hour. Don't bake URLs into static HTML or long-lived caches — re-generate per render or per session.

manage_storage({
  app_id: "app_abc123",
  action: "download_url",
  object_id: "9c14b2e0-..."
})
// → { download_url: "https://s3.amazonaws.com/..." }

For lists with many files, resolve URLs in parallel:

const urls = await Promise.all(
  posts.map(p => getDownloadUrl(p.image_id))
);

If the caller is unauthorized, the response is `404` (not `403`) — Butterbase deliberately hides existence to avoid leaking object IDs.

---

4. Access control

Three tiers, evaluated in order:

| Caller | What they can read | |--------|--------------------| | Service key (`bb_sk_*`) | Everything in the app — RLS bypassed | | End-user JWT | Files where `(user_id === caller_id) OR object.public === true OR app.publicReadEnabled === true` | | Anonymous (no auth) | Only public objects (and only if app access mode allows anon) |

Per-object public flag

Set at upload time:

manage_storage({ app_id, action: "upload_url", filename, content_type, size_bytes, public: true })

Use this for one-off public files (a marketing image, a shared avatar) without flipping the whole app to public-read.

App-wide public read

manage_storage({
  app_id: "app_abc123",
  action: "update_config",
  publicReadEnabled: true
})

When `true`, any authenticated user in the app can download any file. Uploads and deletes stay user-scoped.

> Storage ACL is hardcoded — you cannot layer Postgres RLS policies on top of `storage_objects`. If you need fine-grained custom rules, gate downloads through a serverless function instead of handing out direct presigned URLs.

---

5. Listing and deleting

manage_storage({ app_id: "app_abc123", action: "list" })

Service key sees everything; end-user JWT sees only their own files. Each item has `id, user_id, key, filename, content_type, size_bytes, created_at`.

manage_storage({ app_id: "app_abc123", action: "delete", object_id: "9c14b2e0-..." })

Permanently removes the S3 object and DB row. **Clear foreign-key references first** (e.g. `UPDATE users SET avatar_id = NULL`) — `manage_storage` doesn't.

---

6. Quotas & error codes

| Limit | Default | Override | |-------|---------|----------| | Per-file size | 10 MB | `storage_config` | | Total app storage | Plan-dependent | Upgrade plan | | Allowed content types | All by default | `storage_config.allowedContentTypes` whitelist |

| Error | When | |-------|------| | `QUOTA_FILE_SIZE_EXCEEDED` (400) | `size_bytes` > per-file limit | | `QUOTA_STORAGE_EXCEEDED` (429) | App total exhausted | | `VALIDATION_INVALID_TYP