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mangaBookmark/backend/AGENTS.md
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sulthan b9f9aea82c docs: secure-coding rules for agents, and refresh stale AGENTS.md top-matter (#16)
Two doc commits: a new secure-coding rules section, plus a fix for top-matter the rebrand left stale.

## `9156525` — secure-coding rules

`AGENTS.md` carried two security invariants (bearer auth, CORS) but nothing about the code an agent actually writes here. That is the gap worth closing: measured rates for AI-generated web/backend code are ~40% vulnerable (Pearce et al.), 45% failing security tests (Veracode 2025), and users *with* assistants shipped SQLi at 36% vs 7% for the control group (Perry et al., Stanford). The failure classes cluster on broken access control, injection, session/error handling and invented dependencies — all live surfaces in this repo.

Rules were **extracted, not pasted**. Every one names a guard that already exists in-tree, so the instruction is *match this*, not *invent something*:

| Rule | Existing anchor |
| --- | --- |
| parameterized SQL only; constants may concatenate | `store.go` — all queries use `?` |
| `html/template` only; no `template.HTML` on stored data | `web.go:85` |
| client-supplied URLs pass the fetch gate | `poller.go:144 fetchableSeriesURL` |
| cap remote bodies | `fetch.go:16 maxBodyBytes` |
| `subtle.ConstantTimeCompare`, never `==` | `middleware.go:22`, `session.go:61` |
| generic error out, detail to log, never log the token | `web.go:151` |
| `X-Forwarded-Proto` for Secure; **rightmost** XFF for IP | `session.go:68,101` |
| cookie flags; expiry checked before signature | `session.go:72-94`, `Verify` |
| validate at handler boundary | `handlers.go:48` `MaxBytesReader` 64 KB, 400 on bad key/status/kind |
| site strings via `el({text})`, never `{html}` | `el()` in both userscripts |
| `fetch()`/`authHeaders()` → `API_BASE` only | existing `authHeaders` |
| `localStorage` = cache/queue, never credentials | shared with site JS |

Plus a dependency rule (stdlib first; verify a package exists before adding — ~20% of LLM-proposed packages don't resolve, which is the slopsquatting vector) and a review gate marking auth/CORS/session/crypto/fetch-gate as security-critical.

Deliberately **excluded**: container signing, k8s admission control, IaC scanning, PII/HIPAA/PCI, C/C++ memory safety. Per OpenSSF's guide for AI assistant instructions, irrelevant rules make a model generate code compensating for attacks that cannot happen. None of those apply to a single-user Go + SQLite + userscript stack.

Sources: OWASP AISVS 1.0 Appendix C, OWASP Top 10 / ASVS v5, OpenSSF *Security-Focused Guide for AI Code Assistant Instructions* (2025-08-01).

## `5d4d890` — stale top-matter

The rebrand rewrote root `AGENTS.md` as a compression pass and switched Bromite -> Violentmonkey, but left the project described as a manga-only tracker over two sites. Six sites, two libraries and two userscripts now exist.

Root `AGENTS.md`:

- *What this is* names both scripts with their site lists, the `kind` column, and the `<site>:<series_id>` key shape.
- Origins constraint generalised past Asura/Demonic.
- Records that **kagane and novelfull are reliably Cloudflare-challenged** and browser-polled over CDP. Without it that bullet list reads as contradicting the code, since the paragraph above asserts blocking is "not universal — and not reliably reproducible".
- Diagram says two userscripts.

`backend/AGENTS.md` — two instances of the same defect, found while verifying the above:

- Store key list gained `novelfull|lightnovelworld` and the `kind` column.
- **`NOVEL_USERSCRIPT_PATH` documented** — it shipped in `main.go:150` undocumented.

The dated Cloudflare paragraph is left verbatim: it is a timestamped observation ("Verified 2026-07-26"), so rewriting it would falsify a record rather than update it. `userscript/AGENTS.md` is untouched; it already documents both novel adapters and the `LIBRARY`/`STORE_PREFIX` split.

## Verification

Docs-only, no code touched. Every code reference above was read at `4229c17` before being cited — the fetch gate, body cap, constant-time compares, cookie flags, handler validation, `el()` helper and both route registrations. No invented line numbers.

## Not addressed here

The `API_TOKEN` literal is committed in plaintext in both userscripts and in their `@downloadURL`/`@updateURL` lines. The new rules say not to propagate it, but the actual remedy is rotation plus build-time substitution, since the value is already in git history. Separate change; flagging it so it does not get lost.

Reviewed-on: #16
Co-authored-by: Sulthan Zaki <sultankiki05@gmail.com>
Co-committed-by: Sulthan Zaki <sultankiki05@gmail.com>
2026-08-06 20:07:34 +07:00

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Guidance for OpenCode (and Claude Code) working under `backend/`. See root `AGENTS.md` for the project-wide architecture diagram, hard constraints, and design system.
- **Backend** (`backend/`): stdlib `net/http` (handful routes, no framework) + `modernc.org/sqlite` (pure Go, `CGO_ENABLED=0` -> static binary -> distroless/scratch image). Reverse proxy terminates TLS; Go service listens plain `:8080`.
Single binary, split into packages under `backend/internal/`: `store`
(Bookmark type, SQLite persistence, migrations), `latest` (background
poller, site parsers, TLS fetcher), `session` (cookie signing, login
rate limiter), `httpmw` (Auth/Gzip/CORS middleware), `api` (JSON
bookmark handlers), `userscript` (userscript-serving handler), `web`
(browser UI handler + `templates/` + `static/`, `go:embed`-ed).
`backend/main.go` is the composition root — the only place that wires
packages together into `newRouter`. Root-level `*_test.go` hold
integration tests that exercise the full router; unit tests for a
package live beside it under `internal/`.
- **Single-user store.** One `bookmarks` table keyed `<site>:<series_id>` (`asura`|`demonic`|`comix`|`kagane`|`novelfull`|`lightnovelworld`), with a `kind` column (`manga`|`novel`) splitting the two libraries. Sync **last-write-wins**. Schema and endpoint list in plan.
- **Endpoints:** `GET /bookmarks`, `PUT /bookmarks/{key}` (upsert; see `updated_at` rule below), `DELETE /bookmarks/{key}`, `GET /healthz` (no auth).
- **Web UI:** same binary serve password-gated browser UI on second
hostname — `GET /` (list, or login page when no session),
`POST /login`, `POST /logout`, `GET /static/*`, htmx fragment endpoints
under `/ui/*`. Templates + assets `go:embed`-ed under
`backend/internal/web/`, so `backend/Dockerfile` must copy the whole
`internal/` tree, not just `*.go`. Sessions stateless
HMAC cookies keyed off `API_TOKEN`; `WEB_PASSWORD` gates them, and when empty,
web routes not registered at all. UI mutations read-modify-write
through `Store.Get` + `Store.Upsert` so `updated_at` rule stays one
place. See `docs/superpowers/specs/2026-07-25-web-ui-design.md`.
**Design-tool caveat:** templates link `/static/style.css` root-absolutely
(correct — served from `/`), but impeccable detector resolves
stylesheet href with `path.resolve(fileDir, href)`, drops directory
on leading `/` and silently skip file. Relative href don't help
either: template's directory isn't its served path. So
`detect.mjs backend/internal/web/templates` reports **false clean** —
always pass `backend/internal/web/static` too. One finding there,
`overused-font` on "Instrument Serif", deliberate identity choice, not debt.
- **Every action that moves series out of list is confirm-gated.**
Archive, finish, remove each open own `.confirm-row` disclosure
(`toggleConfirmRow(key, kind)` in `filter.js`, `kind` ∈
`archive|finish|remove`); restore fire instantly since it's the reversal.
Remove's row wear ember wash, two reversible ones wear `.calm` grey.
`--ember` stay reserved for new-chapter signal: busy bar and inline
error use `--mute`.
- **Latest-chapter poller:** ticker goroutine in same binary re-check
each bookmarked series' newest published chapter from backend's own
network access, so `latest_chapter` stay fresh when user not
browsing. Second, parallel signal — userscript keep own
`maybeCaptureLatestOnSeriesPage`/`backgroundRefreshLatest` logic unchanged.
Two independent clocks: per-bookmark cooldown (`latest_checked_at` column,
enforced by `Store.DueForLatestCheck`'s WHERE clause) and wake interval.
Row stamped *before* fetch so broken series wait out full
cooldown instead of retrying every tick, and writes go through
`Store.Get` + `Store.Upsert` so new chapter never reorders list.
Fetches use `bogdanfinn/tls-client` with Chrome profile as defence in depth
against fingerprint-based blocking; any failure log and skip. kagane and
novelfull sit behind Cloudflare JavaScript challenges the TLS client can't
clear, so they are browser-only: fetched over CDP via `BROWSER_WS_URL`, and
simply not polled when that's unset. See
`docs/superpowers/specs/2026-07-26-server-latest-chapter-polling-design.md`.
Poller's `Store.Get` + `Store.Upsert` not wrapped in transaction, so
userscript `PUT` that commits between the two can get overwritten by
poller's stale re-read — reverting that read progress and, since stored
value now differs, moving `updated_at` and reordering list. Known,
accepted limitation for single-user deployment, not bug to fix.
- **`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.
- **Lifecycle buckets:** `status` on each bookmark is `reading` | `archived` |
`finished`, orthogonal to `favorite`. Archived and finished appear only in
own tab — not in All, Updated, Favourites, or recent strip. Poller keeps
checking archived series and skip finished ones. `finished` settable
only from web UI; `PUT /bookmarks/{key}` reject it with 400.
**Empty incoming status means "keep stored one"** — resolved on the
`VALUES` side of `Store.Upsert`, not conflict clause, since
`excluded.*` is post-evaluation row and default applied there would
wipe bucket on every PUT from client that predates column. See
`docs/superpowers/specs/2026-07-27-status-buckets-design.md`.
- **Config via env:** `API_TOKEN`, `ALLOWED_ORIGINS` (comma list), `DB_PATH`
(default `/data/bookmarks.db`), `PORT` (default `8080`), `WEB_PASSWORD`
(gates browser UI; unset disable it),
`LATEST_CHAPTER_POLL_ENABLED`/`_COOLDOWN`/`_INTERVAL`/`_BATCH`/`_STAGGER`
(background latest-chapter poller; defaults on, `1h`/`10m`/`14`/`20s`).
`USERSCRIPT_PATH` and `NOVEL_USERSCRIPT_PATH` (files served at
`/u/{token}/manga-bookmark.user.js` and `/u/{token}/novel-bookmark.user.js`,
defaults `/userscript/manga-bookmark.user.js` and
`/userscript/novel-bookmark.user.js`, both supplied by bindmount).
`BROWSER_WS_URL` (headless-shell CDP endpoint for kagane and novelfull;
unset disables browser polling and leaves those sites to the userscript
alone).