Download an asset via signed capability URL (no session)

Differently-prefixed public route (NOT under /api/projects). Authorization is the HMAC signature in the query string; no session/role check. Two modes: assetId-based (email_assets row) or internal key-based (dynamic attachment R2 copy). Returns the binary file on success.

Parameters

Query Parameters

exp

required

integer

Expiry (ms epoch), bound into the signature.

sig

required

string

HMAC signature.

assetId

string

Asset id (assetId mode). Mutually exclusive with key.

key

string

Internal R2 key (dynamic-attachment mode); requires filename + contentType.

filename

string

contentType

string

Responses

200

File bytes (Content-Disposition attachment).

Media typeapplication/octet-stream

string format: binary

400

Missing download parameters.

Media typeapplication/json

object

error

required

Human-readable error message.

string

message

string

Example^generated

json

{
  "error": "example",
  "message": "example"
}

403

Invalid signature.

Media typeapplication/json

object

error

required

Human-readable error message.

string

message

string

Example^generated

json

{
  "error": "example",
  "message": "example"
}

404

Asset/object not found, or R2 binding missing.

Media typeapplication/json

object

error

required

Human-readable error message.

string

message

string

Example^generated

json

{
  "error": "example",
  "message": "example"
}

410

Download link expired.

Media typeapplication/json

object

error

required

Human-readable error message.

string

message

string

Example^generated

json

{
  "error": "example",
  "message": "example"
}

503

EMAIL_ASSET_SIGNING_KEY not configured.

Media typeapplication/json

object

error

required

Human-readable error message.

string

message

string

Example^generated

json

{
  "error": "example",
  "message": "example"
}