Hooks

Streamer hooks let you transform what the streamer produces without forking its pipeline. There are two hook points, both passed wherever the streamer is set up (new Streamer({ hooks }), new ServiceWorkerStreamer({ hooks }), or directly to generateManifestFromArchive / generateResourceFromArchive):

type StreamerHooks = {
  manifest?: StreamerManifestHookFactory[]
  resource?: StreamerResourceHookFactory[]
}

Manifest hooks

An ordered list of Manifest transforms. All book-format understanding (OPF/ComicInfo/Apple/Kobo precedence, the viewport layout scan, spine rules) happens in @prose-reader/archive-reader's resolveArchive before your hooks run, so there is a single hook point: your hooks receive the fully mapped manifest (hrefs rebased onto the baseUrl, toc attached) and run just before the final defaults — an unset readingDirection only falls back to ltr after every hook ran, so a hook can still detect "no source decided it".

import type { StreamerManifestHookFactory } from "@prose-reader/streamer"

const forceLandscapeSpreads: StreamerManifestHookFactory =
  ({ archive, baseUrl }) =>
  (manifest) => ({
    ...manifest,
    renditionSpread: "landscape",
  })

const streamer = new Streamer({
  hooks: { manifest: [forceLandscapeSpreads] },
  // ...
})

Each factory receives { archive, baseUrl } and returns the transform; transforms may be async and run in list order. The @prose-reader/cbz package ships ready-made ones (reading-direction detection, panorama splitting) as streamerHooks.manifest.

Caution

Before v2 of the streamer, manifest hooks were split into content/spine/presentation/navigation phases interleaved with built-in format hooks. That taxonomy is gone — pass a single ordered array instead.

Resource hooks

Resource hooks transform individual resource responses (HookResource: { body?, params: { contentType? } }). The streamer applies its built-in fixes this way (calibre quirks, CSS adjustments, self-closing-tag normalization) and your hooks run on top:

import type { StreamerResourceHookFactory } from "@prose-reader/streamer"

const textPlainEverything: StreamerResourceHookFactory =
  ({ archive, resourcePath }) =>
  (resource) => ({
    ...resource,
    params: { ...resource.params, contentType: "text/plain" },
  })