gacha-event-tracker/docs/PRD.md

Gacha Event Tracker — Product Spec

The problem

A player of three or four gacha games is tracking a dozen concurrent, overlapping, time-boxed events across as many different in-game calendars. The information exists — on wikis, in patch notes, in-game — but never in one place and never sorted by the thing that actually matters: what expires next. The failure mode is missing a limited event by a day.

What this app is

A single-page web app that answers three questions:

1. What is running right now, across all my games?
2. What ends soonest?
3. Which of these have I already finished?

What this app is not

• Not an account system. There is no login, no profile, no cloud sync.
• Not a wiki. It does not explain how to complete an event, only that it exists and when it ends.
• Not a notification service. No push, no email, no background alerts. (A browser-local reminder is a plausible v2; it is out of scope for v1.) F14 is not an exception to this: it is the open page disclosing something about itself, in the tab, while the reader is looking at it — nothing is delivered anywhere, and the app is never told to wake anybody up.
• Not a damage calculator, build planner, or pull tracker.

Users

One persona: a player of 2–5 gacha games who checks in a few times a week, most often on mobile.

Most often is not only, and the desktop layout is not the phone layout stretched. Past lg the page splits: what it is telling the reader to do — the next deadlines, tonight's dailies — pins to a rail on the left and stays put, while the lists it is showing them scroll beside it. Below that breakpoint the same split produces the same answer in one column: instructions first. They care about accuracy of end dates above everything else — a wrong date is worse than a missing event, because a missing event sends them to a wiki while a wrong one makes them miss content.

Scope — v1

Games at launch

Game	ID
Genshin Impact	genshin
Honkai: Star Rail	hsr
Zenless Zone Zero	zzz
Wuthering Waves	wuwa
Arknights	arknights
Arknights: Endfield	endfield
Neverness to Everness	nte

Added since launch, on the strength of the release thread (docs/FEEDBACK.md § P1): Infinity Nikki (nikki), Persona 5: The Phantom X (p5x), Reverse: 1999 (r1999), Blue Archive (ba), Fate/Grand Order (fgo), hololive Dreams (holodori). GameId in src/shared/schema.ts is the live answer and SOURCES says which of them actually have a source — this table is the launch scope, not a roster to keep in sync.

Adding a game must require no change to GachaEvent — only a GameId entry, its games.ts metadata, and a source registration. That is the test of whether the data model is right, and it has held: the thirteen games here have cost the event schema nothing. Per-game metadata does occasionally grow (Reverse: 1999 needed resetHourLocal for a 05:00 reset), which is a different file and moves no stored key. A game may have several sources; see docs/INGESTION.md § Three layers.

Features

F1 — Timeline view. A horizontal timeline, one lane per game, spanning a scrollable date range with "today" pinned as a vertical marker. Each event is a bar from startsAt to endsAt. Bars are colored by game, and completed events render at reduced opacity with a check. Clicking a bar opens a detail panel with title, type, exact start/end in the user's local timezone, source link, and a completion toggle.

An event with endsAt: null renders as a bar with a frayed right edge and the label "end date unknown" — it must be visually distinct from an event that ends far in the future.

It is a board rather than a stretch of page: its own pane, scrolling in both directions, with the date axis pinned to the top and every name — the lane's and the event's — pinned to the left. Those three used to scroll away together, which made a wide window worse rather than better: more calendar on screen, and nothing left saying which day, whose game, or which event was being read. A six-week bar starts weeks off-screen, so a name that rides off with its own start date leaves a coloured rectangle behind.

The board draws at most two months of past. A standing login campaign can have been running for half a year, and drawing from the earliest start bought months of empty calendar that nobody scrolls back through and that pushed every other bar off to the right. An event older than the board keeps its faded left edge rather than being redrawn as though it started at the edge — the same honesty the frayed right edge carries for an unannounced end.

F2 — Ends-soonest list. A flat list of all currently running events sorted ascending by end date, with a relative countdown ("ends in 2 days", "ends in 4 hours"). Under 24 hours, the row is emphasized. This is the view that justifies the app, and it is one tap from the timeline.

Which view opens is the reader's answer, not ours. This spec said "calendar (default)" and the app shipped opening on the list; both were a decision made on the reader's behalf and then forgotten on every reload. So the first run asks (F8) and the answer is stored in prefs.view. The list is what the question ships pre-answered with — a reader cannot choose between two layouts they have not seen, and it is the view that answers "what expires next" in one look.

The list is capped and offers the rest. Two games already run to twenty-one live events, and a reader who tried exactly that said the list stopped being usable. Each section shows a handful with an explicit "show all N". This truncates the view only: the order is untouched, and the rows below the cut are still counted in the header, still on the timeline, and one tap away.

F3 — Mark completed. A toggle on every event, in both views. State is written to localStorage immediately and optimistically — there is no server round trip and no failure case. Completed events stay visible but de-emphasized; a filter toggles them out entirely.

F4 — Filters. Filter by game (multi-select, persisted) and by event type. Hiding a game hides it from both views. Preferences persist in localStorage.

F4a — Focus one game at a time. Switching games on and off says which games the reader plays, and is set once. It is the wrong tool for the thing a player of four games actually does while reading: clear one game, move to the next. Doing that with the on/off switches costs two taps per game and leaves the settings panel no longer describing what they play.

So focus is a lens over the filter, not a second filter: a bar at the top of the page, above everything it affects, narrowing every view — headline, dailies, lists, calendar and counts — to one game, with a "next game" control that steps through them and ends by returning to all. It never changes hiddenGames, "All" is always one tap away, and a focus on a game that is switched off or has left the feed is ignored rather than obeyed, so it can never strand the reader on a blank page whose cause is elsewhere. Each chip carries that game's outstanding count, so a game with nothing waiting says so before it is visited.

F5 — Region selection. A user picks Asia / America / Europe once. For events where regionScoped is true, all displayed end times resolve to that region's server reset. This is stored in localStorage and defaults to a guess from the browser timezone, shown as a dismissible "showing America server times — change".

F6 — Export / import. Because there are no accounts, moving between devices is manual: download a JSON file of completed IDs and preferences, upload it elsewhere. Import merges rather than replaces, and never removes a completion the user already has.

F12 — Record your own progress and effort. Three states, not two: untouched, doing it, done. Plus an optional effort estimate — quick, short, long, grind — and a free-text note.

Three states need three targets. A single control cycling untouched → doing → done makes a button labelled "Mark done" produce "doing it", which is the control lying about itself; the detail sheet has an explicit control per state, and its primary action goes straight to done and back.

Effort is not decoration. Combined with the time remaining it answers the question the calendar can't: can I still finish this? The same two days is comfortable for a quick event and hopeless for a grind, so an event carrying an effort estimate gets a "tight" or "running out of time" flag when the remaining time no longer covers it.

The heuristic assumes about an hour of play a day and says so. It never hides or reorders anything — it adds a flag the reader can ignore. An event with no recorded effort never gets a warning, because inferring an estimate in order to warn about it would be fabricating their input.

F13 — Your own games and your own events. No feasible adapter set covers everyone. Fourteen games were named in the first release thread and the reader with the largest collection asked for exactly one thing — "can you add a custom game option, we can input our own event description and time frames?" — and, separately, said they would wait until "more are added or we are able to customise it." That is the tail no source list reaches, and it needs no scraping, no ToS question and no server.

So a reader can define a game (a name and a lane colour) and enter events against it, or against a game the app already tracks when a source missed something. Their events sit in the same lists, timeline, sort and filters as scraped ones, and everything they can do to a scraped event — done, doing, effort, note, ignore, daily checklist — works identically.

Four constraints, each protecting something that already exists:

• Their events are visibly theirs. A hand-entered date is never attributed to a source and never carries a source link. The reader must be able to tell, at a glance, which dates the app went and found and which ones they typed.
• Their events never touch the ingest pipeline. sanitize.ts and merge.ts exist for pages we do not control; a reader's own typing is neither untrusted markup nor a second opinion to reconcile. Nothing they enter is fetched, parsed, merged, scored or quarantined.
• Their IDs live in their own key space. Never ${game}:${slug}:${date} — see docs/DATA-MODEL.md § Reader-authored key spaces.
• They are in the backup. An export that omitted hand-entered events would be a lossy backup, which is the same argument the code already makes for streaks. This is the only copy — there is no server to restore from.

F8 — First-run setup. Before any events are shown, the reader picks which games they play, and how they want to read them. A calendar full of games they don't play is worse than an empty one — it buries the thing they came for. Nothing is preselected and the button stays disabled until something is chosen; guessing on their behalf and hoping they notice is worse than asking. The choice is stored as hidden games, the inverse, so a game added later appears by default rather than staying invisible forever.

The view question (F2) sits under it, with each option drawn rather than only described — the words "list" and "timeline" mean nothing until you have seen this app's version of them. Unlike the games, it arrives already answered, and the screen says where to change it afterwards: the tabs are small text in a corner, which is the one control a first-time reader will not find on their own.

F9 — Ignore an event. Distinct from completing one. "Done" keeps an event visible and counted; "not interested" removes it from both views entirely. Ignored events stay recoverable: a count and a reveal toggle appear in settings once there is something to reveal.

F10 — Works offline. The reader's question is answered entirely by data already on the device, and countdowns run off the local clock, so losing signal should not lose the app. A service worker caches the shell and serves the last feed it downloaded. Offline is disclosed in the header and above the footer — see F7; stale data must never be presented as current.

F11 — Credit and disclaimer. The sources that compile these calendars, and the studios that make the games, are named on the same screen as the data rather than one navigation step away. The page states plainly that it is unofficial and unaffiliated, and that the source page is the authority when the two disagree.

F14 — Say when a new version of the app is ready. F10 caches the shell so the app survives losing signal, and the same cache is why a reader who never closes the tab keeps running the version they first loaded. A new game, a repaired parser or a corrected date then reaches their device and sits there unused, with the page looking unchanged and nothing saying why. Presenting an old app as current is the same failure as presenting old events as current (F7), so it is disclosed the same way: a notice on any screen, with one action that reloads into the new version.

It is an offer, not a swap. The app never reloads itself — doing so mid-sentence while someone types in their own event (F13) would cost them work to save the app a tap. It says what a reload costs (their place on the page) and what it does not (everything they have marked, typed or ticked lives in localStorage, not in the bundle). Dismissing is free and the offer returns on the next load, which is also why it need not nag.

A first install is not an update and is not announced — nothing is being replaced, and telling a first-time reader a new version is available would be false. Neither is a feed refresh: new events arrive without a reload, and calling that a new version would train readers to dismiss the notice unread.

F7 — Freshness disclosure. The footer shows when the feed was last updated, per game. If a game's data is more than 48 hours stale, its lane carries a warning badge. Never present stale data as current — the whole value proposition is trust in the dates.

Out of scope for v1

Accounts and sync; push notifications; in-game resource or pull tracking; native mobile apps (the web app installs to a home screen, which is enough); localization beyond English.

Two entries left this list after v1 shipped and readers used it. Per-event checklists became F12 and the daily strip; user-submitted events became F13, on the strength of the release thread — the reader juggling ten games asked for it twice and asked for nothing else, and no adapter roadmap answers them. The decision is recorded here rather than left implicit in the code.

Success criteria

• A user can identify their next expiring event within 5 seconds of load, on mobile.
• Published end dates are correct for 99%+ of events. This is a data-quality target, and it is what the review gate in docs/INGESTION.md exists to protect. Prefer publishing nothing to publishing a guess.
• Adding a new game is an adapter plus a fixture plus a test — no schema migration, no client change.

Quality bar for dates — the core product rule

The app's entire value is that the dates are right. Therefore:

• An event with an uncertain end date is published with endsAt: null, not with a plausible guess.
• An event whose confidence is below threshold, or whose sources disagree, is not published at all until a human approves it.
• Every event links to its source so a skeptical user can verify in one click.

An empty calendar is a recoverable disappointment. A confidently wrong end date is the failure this product exists to prevent.

Open questions

• Does the calendar need a month/grid view, or is the timeline enough? (Assumption: timeline is enough for v1; revisit after use.)
• Should an ignored event still count toward the "N live" header total? (Assumption: no — ignoring means gone.)
• Should events the user has hidden by game filter still count toward "ends soonest"? (Assumption: no — the filter is global.)
• Is 6 hours the right refresh cadence? (Assumption: yes; events are announced days ahead, so sub-hourly refresh buys nothing and is rude to the sources.)