gacha-event-tracker/docs/ARCHITECTURE.md

Architecture

Shape

One Bun process serves the static React build, exposes a read-only JSON API, and runs the ingestion scheduler on a timer. SQLite is the only datastore. There is no auth layer because there are no users.

                    ┌──────────────────────────────────────────────┐
   game wikis  ───► │  Bun process                                 │
   news pages       │                                              │
                    │   scheduler (every 6h)                       │
                    │        │                                     │
                    │        ▼                                     │
                    │   ingest pipeline                            │
                    │   fetch → parse → validate                   │
                    │        → reconcile → gate → publish          │
                    │        │                    │                │
                    │        │                    └──► quarantine  │
                    │        ▼                          │          │
                    │   ┌─────────────┐                 │          │
                    │   │  SQLite     │◄────────────────┘          │
                    │   └─────────────┘      /review (127.0.0.1)   │
                    │        │                                     │
                    │        ▼                                     │
                    │   GET /api/events        static React build  │
                    └────────┬─────────────────────────┬───────────┘
                             │                         │
                             ▼                         ▼
                        browser fetch            browser render
                                  │
                                  ▼
                        localStorage: completions,
                        filters, region  ← never leaves the device

The pipeline makes no third-party API calls beyond fetching source pages. There is no inference anywhere, at ingest time or in a request path.

Layout

src/
  server/
    index.ts            Bun.serve entry: static + API + scheduler bootstrap
    routes/
      events.ts         GET /api/events, /api/events.json
      games.ts          GET /api/games
      review.ts         /review UI + approve/reject (localhost-bound)
      health.ts         GET /api/health
    db/
      client.ts         bun:sqlite handle, WAL, pragmas
      migrations/       NNN-name.sql, applied in order at boot
      queries.ts        all SQL lives here — no SQL in route handlers
  ingest/
    scheduler.ts        timer + jitter + per-source lock          [not built]
    pipeline.ts         the 6 stages, orchestration only          [not built]
    html.ts             flat-table HTML reader (no dependency)    ✓ built
    dates.ts            six deterministic date formats            ✓ built
    merge.ts            cross-source dedupe, corroboration        ✓ built
    validate.ts         zod parse + calendar sanity rules         [not built]
    reconcile.ts        diff vs published, confidence, conflicts  [not built]
    parsers/
      types.ts          SourceParser interface                    ✓ built
      game8.ts          game8.co article calendars                ✓ built
      wikigg.ts         wiki.gg mp-event templates                ✓ built
      index.ts          parser registry                           ✓ built
    adapters/
      types.ts          Adapter interface, ParseContext           ✓ built
      index.ts          SOURCES registry, parseGame()             ✓ built
  shared/
    schema.ts           zod schemas — the contract, both sides    ✓ built
    time.ts             clocks, urgency, region resets, captions  ✓ built
    games.ts            per-game name, hue, and reset clock       ✓ built
    feed.ts             the /api/events.json wire contract        ✓ built
  client/                                                         ✓ all built
    main.tsx            render + service worker registration
    App.tsx             shell, views, filters, onboarding gate
    api.ts              typed feed fetch, schemaVersion refusal
    sw.js               offline: shell cache, feed fallback
    manifest.webmanifest, icon.svg
    components/
      NextUp.tsx        the hero countdown          (PRD F1)
      EventRow.tsx      row + meter + caption       (F2, F3)
      Meter.tsx         the depletion meter
      Legend.tsx        what the bars and colours mean
      Timeline.tsx      calendar lanes              (F1)
      EventDetail.tsx   detail sheet, ignore action (F9)
      ProgressControls  status, effort, note        (F12)
      Dailies.tsx       today's strip, per-game reset clocks
      DailyChecklist    one repeating event's whole run
      Fireworks.tsx     the burst when the last daily lands
      GameFocus.tsx     one game at a time          (F4a)
      Controls.tsx      games, region, export/import(F4, F5, F6)
      Welcome.tsx       first-run game picker       (F8)
      Toast.tsx         undo an ignore
      UpdateNotice      a newer app is installed and waiting  (F14)
      Colophon.tsx      credit, disclaimer, repo link
    state/
      storage.ts        namespaced, versioned localStorage
      useMarkSet.ts     ignores (and the superseded completions shape)
      useProgress.ts    status, effort, note, daily override  (F12)
      useDailyLog.ts    which game-days are ticked off
      usePrefs.ts       region, filters, focus, onboarding flags
      sort.ts           deadline order, or what you're partway through
      lens.ts           who sees which rows — focus, outstanding, next-to-expire
      useAppUpdate.ts   is a newer build waiting, and taking it   (F14)
serve.ts                static server + /api/health              ✓ built
scripts/
  build-feed.ts         fixtures → public/data/events.v1.json     ✓ built
  build-static.ts       shell + worker into public/, build-stamped ✓ built
  parse-fixture.ts      run one adapter offline                   ✓ built
fixtures/<game>/        checked-in raw HTML + expected parse output

Request paths

Route	Purpose	Notes
GET / + assets	React SPA	Served from the bun build output
GET /api/events?from&to&game	Filtered feed	ETag + Cache-Control: public, max-age=300
GET /api/events.json	Whole published feed	Cheap; the client mostly uses this and filters locally
GET /api/games	Game metadata: id, name, color, lastUpdatedAt	Drives the freshness badges (F7)
GET /api/health	Per-source last-success, quarantine depth	For an operator, not the UI
GET /review	Quarantine review UI	Bound to 127.0.0.1 only
POST /api/review/:id/approve | /reject	Promote or discard a quarantined event	Same binding

Why /review needs no auth

Bun.serve runs two listeners: the public one on 0.0.0.0:PORT with the SPA and /api/*, and a second on 127.0.0.1:ADMIN_PORT with /review and /api/review/*. The review routes are not registered on the public listener at all — they are unreachable from off-box, so there is nothing to authenticate. This is the mechanism that satisfies "no logins" without leaving an open admin endpoint on the internet.

This is load-bearing. If someone later puts a reverse proxy in front of the admin port, or merges the two listeners "to simplify", the review UI becomes a public write endpoint. Any change in that area needs an explicit auth story first.

Data flow, concretely

1. Scheduler wakes every 6h (± jitter). For each source not fetched within its minIntervalMs, it acquires a per-source lock row and enqueues a run.
2. Pipeline executes the seven stages in docs/INGESTION.md. Every stage writes to ingest_runs so a failure is diagnosable after the fact without re-running.
3. Publish upserts into events by stable ID, bumping version and updatedAt when any field changed. Events that vanish from a source are not deleted — they are marked status = 'delisted' so a source outage cannot silently empty the calendar.
4. Client fetches the feed, merges the completion set from localStorage by event ID, and renders. Merge is a client-side join; the server never learns what the user completed.

Concurrency and failure

• One in-flight run per source, enforced by a lock row with a stale-lock timeout of 15 minutes.
• A source that fails keeps its previously published events. A failed run never deletes or blanks data — worst case, the game's lane goes stale and gets a warning badge (F7).
• Three consecutive failures for one source raises its health to failing in /api/health. It does not stop the schedule; a wiki being down for a day is normal.
• Raw snapshots are cached by content hash, so a parser change is always evaluated offline against stored pages rather than by re-fetching.

Deployment

Single process, single SQLite file, no external services at all.

PORT=3000
ADMIN_PORT=3001            # bound to 127.0.0.1
DATABASE_PATH=./data/events.sqlite
INGEST_INTERVAL_MS=21600000
INGEST_ENABLED=true        # false for local UI work — never touches the network
CONFIDENCE_THRESHOLD=0.8
BASE_PATH=/               # trailing slash; set when hosting under a subpath

INGEST_ENABLED=false is the default for local development. Frontend work should run against a seeded SQLite file and cost nothing.

Today

serve.ts serves public/ plus /api/health, and the feed is generated offline from fixtures by bun run build:feed. It emits exactly the shape /api/events.json will, so the real server slots in without the client changing. Reads are confined to public/ by resolving the path and checking it stays inside the root — string-matching .. is not enough, because encodings and URL normalisation both change what the string looks like.

Dockerfile builds and serves this; the image runs typecheck and tests during build, ships no source or toolchain, and runs unprivileged. .github/workflows/ci.yml and .gitlab-ci.yml run the same gates and publish it.

Hosting under a subpath

Assets resolve against a <base href> substituted at build time, the feed URL resolves against document.baseURI so deep links work, and the service worker derives its paths from its own registration scope. BASE_PATH=/gacha-event-tracker/ bun run build for GitHub Pages; without it a subpath deploy 404s on every asset.

Offline

The service worker caches the shell and webfonts (cache-first) and the feed (network-first, falling back to the last copy seen). Countdowns run off the device clock, so the app stays useful with no network. Offline state is surfaced in the header and above the footer — stale data must never be presented as current.

Shipping a new version to an open page

A cache-first shell is what makes the offline story work and what makes a deploy invisible: the reader this app is built for leaves the tab open for days, so a new game, a repaired parser or a corrected date reaches their device and then sits there unused. Presenting an old app as current is the same failure as presenting old events as current, so it is disclosed the same way.

build:static ──► sw.js stamped with a hash of the built shell
                        │
browser byte-compares sw.js on navigation, hourly, and when the tab is
revealed (registration.update)
                        │
   bytes differ ──► new worker installs, precaches, and WAITS
                        │
   registration.waiting ≠ null and a controller exists
                        │
   UpdateNotice: "A new version of Event Clock is ready."  [Reload] [×]
                        │
   Reload ──► postMessage {type:"skip-waiting"} ──► worker activates
          ──► controllerchange ──► location.reload()

Four properties this depends on, each of them load-bearing:

• The worker never calls skipWaiting() on install. Claiming an open page unasked leaves the running bundle and the cached shell on two different builds, with nothing on screen saying so. It activates only on the message the reader's tap sends. A first install has no worker to wait for and activates immediately regardless — and is deliberately not announced, since nothing is being replaced.
• The build id is derived, not remembered. scripts/build-static.ts hashes the built shell (index.html, main.js, styles.css, sw.js source) and substitutes it for __BUILD__ in the worker, so any shell change alters the worker's bytes and is therefore offered. The predecessor was a hand-bumped CACHE_VERSION, which had already been forgotten once. The substitution throws if the placeholder is gone, because the failure mode is silent.
• The feed is not part of the id. It is rewritten twice a day and served network-first, so new events reach an open page without a reload. Calling that a new version would teach readers to dismiss the notice unread.
• The cache name does not move with the build. Everything in it is refetched (cache: "reload", since none of these URLs are fingerprinted) on install, so a per-build bucket would buy nothing and would discard the stored feed — the copy an offline reader is reading.

src/client/state/useAppUpdate.ts holds the client half; sw.js and the hook cannot import each other, so test/update.test.tsx pins both ends of the skip-waiting handshake and the placeholder.

Deliberate non-choices

• No ORM. bun:sqlite plus hand-written SQL in queries.ts. The schema is six tables.
• No Redis / job queue. The scheduler is a timer and a lock row. Restarting the process resumes cleanly because state is in SQLite.
• No server-side rendering. The feed is small and cacheable; a static SPA is enough.
• No websockets. Events change on a scale of hours; a 5-minute cache is more than adequate.