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.)
- 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.
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` |

Adding a game must require no schema change — only a `GameId` entry and a source registration.
That is the test of whether the data model is right. A game may have several sources; see
`docs/INGESTION.md` § Three layers.

### Features

**F1 — Calendar view (default).**
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.

**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; it should be reachable in one tap from the calendar and is the better
default on narrow screens.

**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`.

**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.

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.

**F8 — First-run game picker.**
Before any events are shown, the reader picks which games they play. 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.

**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.

**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; per-event checklists or progress tracking; in-game resource
or pull tracking; user-submitted events; native mobile apps (the web app installs to a home screen,
which is enough); localization beyond English.

## 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.)