Plugin API routes can't return non-JSON responses (e.g. images)

[rhaegalll]

Description

Plugin API route handlers can only return JSON. Whatever a handler returns is wrapped in the standard { success, data } response, so there's no way to serve an image, a file, or anything with a custom content type from a plugin route.

I ran into this building a plugin whose route returns an image: there's no way to actually send the image back to the caller. Returning a Response from the handler doesn't help either.

Expected: a plugin route should be able to return non-JSON content such as an image.

Steps to reproduce

1. Add a plugin route whose handler returns an image:

   routes: {
     image: {
       handler: async () =>
         new Response(pngBytes, { headers: { "Content-Type": "image/png" } }),
     },
   }

2. Call the route: GET /_emdash/api/plugins/<plugin>/image.

3. The image isn't returned

Environment

• emdash version: v0.29.0
• Node.js version: 22.16.0
• Runtime: Cloudflare Workers

Logs / error output