Document and package opt-in source worker

docs/scraper-service.md

@@ -5,6 +5,32 @@ It owns the durable queue and is the only process allowed to run a queued archiv
 The browser never contacts it directly: authenticated admin routes in `server.js`
 proxy commands to its private HTTP API.
 
+## First-party source parser pilot
+
+The WeebCentral parser is now a reviewed first-party module in
+`scraper/plugins/weebcentral.js`. By default it runs in the scraper process,
+preserving the existing deployment. To test process isolation in Compose, start
+the `source-plugins` profile and set `SOURCE_PLUGIN_URL` for the scraper to
+`http://source-plugin-weebcentral:8094` (for example via the Compose environment).
+Both settings are required; enabling the URL without a healthy worker causes
+WeebCentral discovery to fail closed and retain its checkpoint. Remove the URL
+to roll back. Do not restart a live scraper merely to try this option; use the
+normal checkpoint-safe deployment procedure.
+
+The worker has no published port, egress network, library/data mount, or token.
+Only the existing rate-limited scraper HTTP client fetches remote HTML/images.
+The worker accepts bounded HTML for four parsing steps over its internal-only
+network. It loads only modules listed in the static first-party registry; there
+is no runtime plugin download or execution of Uchiyomi packages. This is a
+parser-isolation pilot, **not yet** a complete generic source-plugin contract,
+or migration of the MangaDex runner. Parsed catalog and image URLs are checked
+before use, and parser requests/responses are size-bounded. When the worker is
+enabled, WeebCentral requests use a pinned-DNS HTTPS transport that validates
+each redirect and stops on access errors; the ordinary in-process path is not
+changed. Public image hosts are not yet restricted to a reviewed CDN allowlist.
+Keep the profile off in production until a separate deployment validation is
+completed.
+
 ## Start and storage
 
 ```bash