kagane serves cover images from behind the same Cloudflare challenge as
its pages and with cross-origin-resource-policy: same-origin. The second
header is the decisive one: no <img> on the web UI's origin can load a
kagane cover even from a browser that already holds the clearance cookie,
verified 2026-08-08 by loading one from a foreign origin with and without
a referrer. Hot-linking cannot be made to work, so every kagane series
rendered the monogram placeholder.
Bookmark.CoverURL rewrites a stored kagane og:image to /img/kagane/{id}
and returns every other cover untouched; the templates render .CoverURL
in place of .Cover. The endpoint is session-gated like every other UI
route, and hands the id to the shared headless browser, whose fetch is
same-origin with kagane and therefore satisfies both the challenge and
the CORP header. Results are memoised in-process, so a cover costs one
navigation per deployment lifetime.
The id is matched against a UUID regex before it reaches the browser.
That gate is load-bearing rather than tidiness: the cover is a stored
client-supplied string, so an unvalidated one turns the endpoint into an
SSRF primitive aimed at the deployment's own network. ServeMux
path-cleans a traversal into a redirect before the handler runs, but the
handler does not rely on that, and a test pins it.
With BROWSER_WS_URL unset there is no browser and the endpoint answers
404 rather than reaching for a nil fetcher - the same degrade-to-
userscript behaviour the poller already has for these sites.
Tracks read progress on comix.to and kagane.to alongside asura and demonic, in both the userscript and the backend.
Implements `docs/superpowers/plans/2026-08-03-comix-kagane-support.md`.
## Userscript
- `comix` adapter — `/title/<id>-<slug>`; only the id prefix is identity (the slug follows the title). No `og:image`, so the cover is matched by `alt`.
- `kagane` adapter — reader URLs are uuids with no chapter number, so it comes out of `og:title`; anchor scanning is structurally impossible, replaced by `latestChapterFromApi` against kagane's same-origin JSON API.
- `seriesId` threaded through `latestChapterFromAnchors` so comix can scope its scan to its own series and a recommendation strip cannot win the maximum.
- `@match` for both hosts, panel chips, v1.6.0.
## Backend
- `latestChapterFrom` cases: comix parses the SSR JSON state blob (`latestChapterUrl`, scoped to the series id); kagane parses API JSON (`chapter_no`).
- Poller allowlist extended; `Poller.BrowserFetch` with `fetcherFor(site)` routes kagane to a browser fetcher. Nil means kagane is not polled at all — never a fallback to the TLS fetcher, which would only ever retrieve a challenge page.
- `BrowserFetcher`: chromedp against a `headless-shell` sidecar. kagane sits behind a Cloudflare JS challenge that no TLS fingerprint clears, and the request is made inside the page rather than by replaying `cf_clearance`.
- `BROWSER_WS_URL` wiring, sidecar in both compose files (no `ports:`, dedicated non-external network), Dockerfile on `golang:1.26-alpine` — chromedp requires go 1.26.
- Web UI `--comix` / `--kagane` tokens in both colour branches.
## Notes for review
- `series_url` is client-supplied and a headless browser is a strong SSRF primitive, so kagane's host is pinned twice: in `fetchableSeriesURL` and again in `kaganeAPIURL`.
- Three chained defects found during verification made the browser path dead under Compose (sidecar flag collision, Chrome's Host-header DNS-rebinding check, the wrong chromedp option). Fixed; the compose comments record the wrong configurations too, so they don't get "simplified" back.
- `ALLOWED_ORIGINS` now includes both new origins. Without it every write from comix/kagane silently fails CORS preflight, parks in the retry queue, and drops at the cap.
## Verification
221 backend tests, 32 userscript tests, static `CGO_ENABLED=0` build, both compose configs.
Two gaps, both real:
1. The userscript on live pages via Violentmonkey needs a human browser profile — not run. Check: comix series page (title/cover, no chapter), comix chapter page (records the number; an *older* chapter must not regress it), comix SPA navigation without reload, kagane series page (og:image cover), kagane reader (number from `og:title`), both chips opening the right sites.
2. The kagane browser path has not completed end-to-end anywhere. Dial/navigate/fetch is confirmed, but Cloudflare 403'd headless-shell's Chrome on every attempt from the dev sandbox, and comix's poll-through-Docker was blocked by that environment's TLS interception. Both environment-dependent rather than branch defects — the first real deploy is the actual verification.
Reviewed-on: #13
Co-authored-by: Sulthan Zaki <sultankiki05@gmail.com>
Co-committed-by: Sulthan Zaki <sultankiki05@gmail.com>
sulthan