sulthan
741b23322b
Fixes five reported symptoms across comix.to and kagane.to. Diagnosing them turned up two latent bugs underneath, both of which had to be fixed for the kagane cover work to function at all.
## Reported symptoms and their causes
| # | Symptom | Cause |
|---|---------|-------|
| 1 | comix bookmark titled `Comix - Read Comics online for free` | comix is an SPA that rewrites `document.title` on client routing but never touches the server-rendered `og:title`. The adapter read `og:title`, so a cold load stored the homepage's title. |
| 2 | next comix bookmark gets the *previous* series' title | Same cause. After an in-page hop, `og:title` still holds whatever page loaded first. |
| 3 | comix cover shows the placeholder | comix serves no `og:image` at all, so `coverFromPage()` had nothing to read. |
| 4 | kagane chapter never appears in the bookmark list | Reader URLs carry no chapter number, so it is parsed out of `og:title`. Volume-numbered series render `"<Series> - Volume <v> Chapter <n>"`, which the suffix regex did not match, so `chapterNum` came back null and nothing was recorded. |
| 5 | kagane title includes the chapter, e.g. `SP Baby - Volume 1 Chapter 1` | Same unmatched regex — the tail was never stripped. One fix covers 4 and 5. |
| 6 | kagane cover blocked in the web UI | kagane serves covers behind its Cloudflare challenge **and** with `cross-origin-resource-policy: same-origin`. No `<img>` on the UI's origin can load one even from a browser holding the clearance cookie. Hot-linking cannot be made to work. |
## What changed
**Userscript.** comix titles now come from `document.title` with the chapter page's `" - Ch.<n>"` tail stripped, and the cover is the `img` whose `alt` matches the cleaned title. comix fills `document.title` a beat *after* the URL changes — later than the nav watcher's 300 ms snapshot — so the watcher also re-detects when the `detect()` signature changes, not only when the URL does. The kagane suffix regex takes an optional `Volume <v> ` segment. All three page shapes were captured live on 2026-08-08 and pinned as regression tests.
**Cover proxy.** `Bookmark.CoverURL()` rewrites a stored kagane `og:image` to `/img/kagane/{id}`; templates render `.CoverURL` instead of `.Cover`. The endpoint is session-gated like every other UI route and fetches through the shared headless browser, which is same-origin with kagane and so satisfies both the challenge and the CORP header. Results are memoised in-process, so a cover costs one navigation per deployment lifetime. With `BROWSER_WS_URL` unset the endpoint answers 404 rather than reaching for a nil fetcher — the same degrade-to-userscript behaviour the poller already has.
The image 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 this 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 depend on that, and a test pins it.
## Two latent bugs found underneath
**`BrowserFetcher.run` never let a challenge solve.** It navigated, waited for `body`, read once, and closed the tab — roughly half a second end to end. The Cloudflare interstitial has a `body` too, so `WaitReady` was satisfied by the challenge page itself. This made the challenge *unclearable* rather than merely slow: an interstitial needs several seconds of a live page to solve itself and write clearance into the browser's shared cookie jar, so tearing the tab down first means every subsequent call is challenged exactly like the one before it. `run` now holds one tab and re-reads until the caller's predicate reports an answer, bounded by `challengeTimeout` and the caller's own deadline. Exhausting the budget maps back to the 403 the poller already expects, keeping a challenged site distinct from a broken transport.
**`chromedp/headless-shell` cannot clear kagane's challenge at all.** It is a stripped Chrome build and the tells are structural rather than a header: `navigator.webdriver` is true, the plugin list is empty, and the client hints are Chromium- rather than Chrome-branded. Overriding `webdriver` through CDP was tried on its own and changed nothing.
All measured 2026-08-08 from one IP against the same cover, so the comparisons are like for like:
| Browser | Result |
|---------|--------|
| `chromedp/headless-shell:stable` | never cleared (90 s) |
| `zenika/alpine-chrome` | never cleared — ships Chrome 124, old enough that Cloudflare refuses it and old enough to break chromedp's CDP structs |
| `google-chrome`, default UA | never cleared (60 s) — `--headless=new` advertises `HeadlessChrome` |
| `google-chrome`, stock UA, `TZ=UTC` | never cleared (90 s) |
| `google-chrome`, stock UA, any non-UTC `TZ` | **cleared in ~4 s** |
Both remaining tells are load-bearing, and each was tested in isolation. `chrome/` is a Debian image with `google-chrome-stable`, a UA whose version is read back out of the binary at startup (a hardcoded one would drift out of step with the `Sec-CH-UA` hints on the next Chrome update and become a fresh tell), and no `--enable-automation`.
### The timezone tell: UTC, not a country mismatch
The first pass concluded the zone had to match the egress IP's country. Re-measuring against the actual deployment case shows that was wrong, and the correction is in `1552dd1`.
The original inference read the host's `/etc/timezone` (`Asia/Bangkok`) and assumed a Thai egress. It isn't — this host egresses from an Indonesian IP. `Asia/Bangkok` cleared not because it matched a country but because it simply isn't UTC, and the two share +07, which hid the distinction. Same container, same Indonesian IP:
| `TZ` | Result |
|------|--------|
| `UTC` | never cleared (60 s, **twice**) |
| `Asia/Jakarta` | cleared in 4 s |
| `America/New_York` | cleared in 4 s |
`America/New_York` matches neither the country nor the offset nor the hemisphere and clears just as fast. A UTC clock is itself the bot signal — Cloudflare scores it as the datacenter default — and any real zone satisfies the check. `BROWSER_TZ` therefore needs a plausible zone, not a geolocated one, and a deployment that changes region need not keep it in sync.
One sharp edge remains: the usual `-v /etc/localtime:/etc/localtime:ro` does **not** work. Chrome resolves the zone through ICU, which takes the name from that path's symlink target and ignores the file's contents, so glibc reports the host zone while Chrome still reports UTC. `/etc/timezone` carries the name and is mounted instead.
Chrome also binds its DevTools port to loopback and silently ignores `--remote-debugging-address`, which is why headless-shell fronted it with socat. This image does the same, so it stays a drop-in: the compose service keeps the `headless-shell` name and its pinned address, and `BROWSER_WS_URL` is unchanged.
## Verification
```
go test ./... all packages ok
node --test 37 + 12 pass, 0 fail
SMOKE_BROWSER_WS_URL=... go test -run TestSmokeKagane ./internal/latest
TestSmokeKaganeImage PASS (5.29s) fetched 56710 bytes of image/webp
TestSmokeKaganeGet PASS (1.17s) status=200, real chapter-list JSON
```
The smoke test ran against the exact compose configuration — built image, empty `BROWSER_TZ`, `/etc/timezone` mounted, cold profile — hitting real kagane.to. It skips unless `SMOKE_BROWSER_WS_URL` names a sidecar, so `go test ./...` stays hermetic and Docker-only.
A red smoke run means the challenge is not clearing from that IP, which is a live, time-varying fact to re-check rather than necessarily a defect.
## Security invariants
- Auth unchanged. `/img/kagane/{id}` is session-gated by `requireSession`, the same guard as every other UI route.
- Outbound fetch gated: the id is UUID-validated before it reaches the browser, keeping the existing rule that a client-supplied string never selects a fetch target unchecked.
- No new secrets, no new logging of credentials, no change to CORS, sessions, or crypto.
- Templates still escape everything; `.CoverURL` returns a plain string and is not wrapped in `template.HTML`/`URL`.
- One new dependency-free image (`chrome/`) built from Debian plus Google's own apt repo; no new Go modules.
## Deploying
Needs `docker compose build headless-shell`.
**A UTC host must set `BROWSER_TZ`, or kagane silently stops working.** With it unset the sidecar falls back to the host's `/etc/timezone`; on a UTC server that yields UTC, which is the one value that never clears. Any real zone works — `BROWSER_TZ=Asia/Jakarta` for the current deployment. `.env.example` now documents this; it previously did not mention the knob at all.
Only the browser sidecar reads `BROWSER_TZ`. The backend keeps its UTC clock, and stored timestamps are unix ms, so nothing else shifts.
## Deliberately not done
Retry/backoff around the cover proxy, and a panel-side cover fix. The panel renders no covers, and covers cache in-process after the first fetch. Worth adding if kagane starts rate-limiting.
## Correction after review of the deployment case
`1552dd1` was added after the branch was first pushed: the deployment host runs UTC with an Indonesian egress IP, which prompted re-measuring the timezone claim and falsifying it. The earlier commits' reasoning is left intact rather than rebased away, so the diagnostic trail — including the wrong turn and what disproved it — stays readable.
Reviewed-on: #37
Co-authored-by: Sulthan Zaki <sultankiki05@gmail.com>
Co-committed-by: Sulthan Zaki <sultankiki05@gmail.com>
154 lines
12 KiB
Markdown
154 lines
12 KiB
Markdown
Guidance for OpenCode (and Claude Code) working under `backend/`. See root `AGENTS.md` for the project-wide architecture diagram, hard constraints, and design system.
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- **Backend** (`backend/`): stdlib `net/http` (handful routes, no framework) + Postgres over `jackc/pgx/v5` (pure Go, `CGO_ENABLED=0` -> static binary -> distroless/scratch image). Reverse proxy terminates TLS; Go service listens plain `:8080`.
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Single binary, split into packages under `backend/internal/`: `store`
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(Bookmark type, Postgres persistence, migration runner), `latest` (background
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poller, site parsers, TLS fetcher), `session` (cookie signing, login
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rate limiter), `httpmw` (Auth/Gzip/CORS middleware), `api` (JSON
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bookmark handlers), `userscript` (userscript-serving handler), `web`
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(browser UI handler + `templates/` + `static/`, `go:embed`-ed).
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`backend/main.go` is the composition root — the only place that wires
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packages together into `newRouter`. Root-level `*_test.go` hold
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integration tests that exercise the full router; unit tests for a
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package live beside it under `internal/`.
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- **Schema is migration-owned.** `internal/store/migrations/*.sql` is
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`go:embed`-ed and applied on every start by `store.migrate`: one numbered
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file per change, one transaction each, versions recorded in
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`schema_migrations`. Files are **append-only** — editing an applied one
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changes nothing on a database that already ran it. No column probing, no
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data-fixup migrations: both were SQLite-era machinery and are gone.
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- **Tests need Docker.** `internal/pgtest` starts one `postgres:17-alpine`
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container per test binary (`TestMain` -> `pgtest.Main`) and hands each test
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its own database (`pgtest.URL(t)`). A package whose tests touch the store
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must have that `TestMain`.
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- **Reader-owned store, four tables.** `readers` is keyed by Discord user ID
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and carries the SHA-256 of the Reader's userscript credential plus a
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`token_epoch` (issue #24). Credentials are derived, never stored: `token.Token(TOKEN_KEY, discord_id, epoch)` (HMAC, `internal/token`), and only its SHA-256 sits in `readers.token_sha256`, so install URLs can be rebuilt after any restart while a database leak yields nothing but hashes. The seed creates the **owner** row at startup; its epoch-0 hash is refreshed on every start **only while the row has never been rotated**, so a restart can never resurrect a rotated-away credential. Every other row is created by that Reader's own first login (`Store.EnsureReader`, idempotent on `discord_id`, and it never rewrites an existing row's hash). Rotation is `Store.RotateToken` (epoch bump + hash rewrite in one transaction), driven by the web UI.
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`series` keyed `(site, series_id)`
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(`asura`|`demonic`|`comix`|`kagane`|`novelfull`|`lightnovelworld`) owns the
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shared facts — title, cover, canonical URL, `kind` (`manga`|`novel`),
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Latest Chapter, `latest_checked_at` — and `bookmarks` holds only what
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differs between readers: progress, favourite, lifecycle bucket,
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`updated_at`. A bookmark is keyed `(reader_id, site, series_id)` — no
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surrogate id; the wire `key` is derived as `site:series_id` on read — and
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every store read/write is scoped to the reader it names. Auth resolves the
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acting Reader from the presented credential (`httpmw.Auth`) and nothing
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else — there is no unauthenticated-by-Reader route and no global token; the
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reader id travels in the request context. Sync **last-write-wins**; the wire format
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stays flat (ADR-0004). `Store.Upsert` decomposes one flat body across two
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tables and enforces the ownership rule: client `title`/`series_url`/`cover`
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are written only when the series row is new (ADR-0003).
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- **Endpoints:** `GET /bookmarks`, `PUT /bookmarks/{key}` (upsert; see `updated_at` rule below), `DELETE /bookmarks/{key}`, `GET /healthz` (no auth).
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- **Web UI:** same binary serve the browser UI on a second
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hostname — `GET /` (list, or login page when no session),
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`GET /auth/discord` + `GET /auth/discord/callback` (Discord OAuth,
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ADR-0002), `POST /logout`, `GET /static/*`, htmx fragment endpoints
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under `/ui/*`. Templates + assets `go:embed`-ed under
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`backend/internal/web/`, so `backend/Dockerfile` must copy the whole
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`internal/` tree, not just `*.go`. Sessions are rows in the `sessions`
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table: the cookie carries only an opaque id, looked up (and expiry-
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checked) on every request, and deleting the row revokes the session.
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Guild membership *is* registration (issue #27): `discordCallback` gates on
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membership (and `DISCORD_REQUIRED_ROLE` when set) and then calls
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`Store.EnsureReader`, so a refusal creates nothing and a returning Reader
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reuses their row. The owner is the only Reader with administrative reach:
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`POST /readers/{id}/revoke` (404 for anyone else) drops that Reader's
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sessions, and the `readers` panel renders only on the owner's page.
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A Reader with no bookmarks at all sees `listView.Fresh`, whose empty state
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offers both install links instead of describing a filter.
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UI mutations read-modify-write
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through `Store.Get` + `Store.Upsert` so `updated_at` rule stays one
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place. See `docs/superpowers/specs/2026-07-25-web-ui-design.md`.
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**Design-tool caveat:** templates link `/static/style.css` root-absolutely
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(correct — served from `/`), but impeccable detector resolves
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stylesheet href with `path.resolve(fileDir, href)`, drops directory
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on leading `/` and silently skip file. Relative href don't help
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either: template's directory isn't its served path. So
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`detect.mjs backend/internal/web/templates` reports **false clean** —
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always pass `backend/internal/web/static` too. One finding there,
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`overused-font` on "Instrument Serif", deliberate identity choice, not debt.
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- **Every action that moves series out of list is confirm-gated.**
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Archive, finish, remove each open own `.confirm-row` disclosure
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(`toggleConfirmRow(key, kind)` in `filter.js`, `kind` ∈
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`archive|finish|remove`); restore fire instantly since it's the reversal.
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Remove's row wear ember wash, two reversible ones wear `.calm` grey.
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`--ember` stay reserved for new-chapter signal: busy bar and inline
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error use `--mute`.
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- **Latest-chapter poller:** ticker goroutine in same binary re-check
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each bookmarked series' newest published chapter from backend's own
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network access, so `latest_chapter` stay fresh when user not
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browsing. Second, parallel signal — userscript keep own
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`maybeCaptureLatestOnSeriesPage`/`backgroundRefreshLatest` logic unchanged.
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Two independent clocks: per-series cooldown (`series.latest_checked_at`,
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enforced by `Store.DueForLatestCheck`'s WHERE clause) and wake interval.
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The poller walks **Series, not Bookmarks** — a series referenced by several
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bookmarks is fetched once per cycle, and the due queue orders
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`reader_count DESC, latest_checked_at ASC` (ADR-0003). Series row stamped
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*before* fetch so broken series wait out full cooldown instead of retrying
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every tick; found chapter written straight to the series row via
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`Store.SetLatestChapter`, so a bookmark's `updated_at` — and the list
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order — is never touched.
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Fetches use `bogdanfinn/tls-client` with Chrome profile as defence in depth
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against fingerprint-based blocking; any failure log and skip. kagane and
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novelfull sit behind Cloudflare JavaScript challenges the TLS client can't
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clear, so they are browser-only: fetched over CDP via `BROWSER_WS_URL`, and
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simply not polled when that's unset. See
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`docs/superpowers/specs/2026-07-26-server-latest-chapter-polling-design.md`.
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The poller's series write is a single-column UPDATE
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(`Store.SetLatestChapter`), not a read-modify-write of the whole bookmark:
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it cannot revert read progress or move `updated_at`, so the old
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stale-re-read race is gone with the Get+Upsert flow.
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- **`updated_at` drives list order, so moves only on real reading progress:** server apply its timestamp when row new or `last_chapter_num` changes, else keep stored value — favouriting series or recording newly published chapter must not reorder list. `PUT` therefore returns row **as stored**, clients must adopt that response rather than own payload. See `plans/2026-07-25-bookmark-list-favorites-design.md` §4.
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- **Lifecycle buckets:** `status` on each bookmark is `reading` | `archived` |
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`finished`, orthogonal to `favorite`. Archived and finished appear only in
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own tab — not in All, Updated, Favourites, or recent strip. Poller keeps
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checking archived series and skip finished ones. `finished` settable
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only from web UI; `PUT /bookmarks/{key}` reject it with 400.
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**Empty incoming status means "keep stored one"** — resolved on the
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`VALUES` side of `Store.Upsert`, not conflict clause, since
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`excluded.*` is post-evaluation row and default applied there would
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wipe bucket on every PUT from client that predates column. See
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`docs/superpowers/specs/2026-07-27-status-buckets-design.md`.
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- **Config via env:** `TOKEN_KEY` (derives every Reader's userscript credential;
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required), `OWNER_DISCORD_ID` (seeds the owner Reader — the administrator and
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the owner of every pre-registration bookmark; required),
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`ALLOWED_ORIGINS` (comma list),
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`DATABASE_URL` (Postgres connection URL, required — no default),
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`PORT` (default `8080`), `DISCORD_CLIENT_ID`/`_CLIENT_SECRET`/`_GUILD_ID`/
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`_REDIRECT_URI` (required; Discord OAuth for the browser UI),
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`DISCORD_REQUIRED_ROLE` (optional role gate, empty by default),
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`DISCORD_API_BASE` (default `https://discord.com/api/v10`),
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`LATEST_CHAPTER_POLL_ENABLED`/`_COOLDOWN`/`_INTERVAL`/`_BATCH`/`_STAGGER`
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(background latest-chapter poller; defaults on, `1h`/`10m`/`14`/`20s`).
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`USERSCRIPT_PATH` and `NOVEL_USERSCRIPT_PATH` (files served at
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`/u/{token}/manga-bookmark.user.js` and `/u/{token}/novel-bookmark.user.js`,
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defaults `/userscript/manga-bookmark.user.js` and
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`/userscript/novel-bookmark.user.js`, both supplied by bindmount; the
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`__API_TOKEN__` placeholder inside them is substituted with the requesting
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Reader's credential at serve time).
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`BROWSER_WS_URL` (CDP endpoint of the `chrome/` sidecar, used by the poller
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for kagane and novelfull *and* by the web UI's kagane cover proxy; unset
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disables browser polling and serves 404 from the proxy, leaving those sites
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to the userscript alone).
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- **kagane covers are proxied, not hot-linked:** kagane serves cover images
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behind the same challenge as its pages and with
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`cross-origin-resource-policy: same-origin`, so no `<img>` on the web UI's
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origin can load one — not even from a browser holding the clearance cookie
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(verified 2026-08-08). `Bookmark.CoverURL` rewrites a stored kagane
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`og:image` to `/img/kagane/{id}`, served by `internal/web/cover.go` through
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`latest.BrowserFetcher.Image` and memoised in-process. The templates render
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`.CoverURL`, never `.Cover`. The id is matched against a UUID regex before it
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reaches the browser: the stored value is client-supplied, so an unchecked one
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is an SSRF primitive pointed at the deployment's own network.
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- **Web UI also owns:** session-gated `GET /install/{manga,novel}-bookmark.user.js`
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(renders the bindmounted script with the acting Reader's derived credential
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substituted in — the credential never appears in page markup, the address
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bar, or a redirect; `?download=1` adds `Content-Disposition: attachment` for
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mobile Violentmonkey, which ignores a `.user.js` navigation) and
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`POST /rotate-token` (atomic epoch bump + hash
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rewrite; invalidates every installed copy, so the panel warns to reinstall
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on all devices).
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Owner-only `POST /readers/{id}/revoke` (drops one Reader's session rows and
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re-renders the `readers` panel; 404 for any non-owner) is the only route that
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reaches across Readers.
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