route.sends_invalid

Route's sends: isn't a media type, or its Output isn't exactly one Bytes field.

Area 7, HTTP; not declinable; the next step is usually the agent's.

sends: names the media type of a body of raw bytes, on a route whose Output has exactly one field, of a type built on Bytes, which is then the body. The media type is a lowercase type/subtype, with any parameters after a ;. It isn't JSON, which is what an Output's own fields are sent as, or text/event-stream, which is what an AiStream is sent as. A route with settle: can't send raw bytes, since they can't say how far the work has got.

Here Scan has a second field, so nothing says what would happen to it:

type Note = Text {    max_length: 200}type Scan = Output {    note: Note    body: Bytes}action a_scan() -> Scan {    return Scan {        note: "A scan."        body: hash.sha256("the scan")    }}routes Scans {    prefix: /scans    GET / {        authentication: RouteAuthentication.none        output: Scan        sends: "application/pdf"        run: a_scan()    }}

   |23 |         sends: "application/pdf"   |                ^^^^^^^^^^^^^^^^^ `Scan` holds 2 fields

Send the bytes alone, with body as Scan's one field, and read the note from a route of its own. See Sending raw bytes.