gacha-event-tracker/snapshots/README.md

Snapshots

Raw pages, exactly as fetched. scripts/refresh-sources.ts writes them; nothing else fetches.

<source-id>.html        the body verbatim — tracked
<source-id>.meta.json   hash, size, charset, ETag, Last-Modified, contentChangedAt, lastConfirmedAt — tracked
<source-id>.state.json  transient run bookkeeping: last attempt and failure streak — gitignored

"Verbatim" means the bytes as served, not text we re-encoded. charset in the metadata records what those bytes are in — the Content-Type header, else a <meta charset> in the page, else UTF-8 — and bytes is the served length. A page in Shift_JIS or Latin-1 decoded as UTF-8 would be stored as a field of U+FFFD with the original bytes gone; re-parsing could never recover it, and the mojibake would reach slugify, moving every event ID for that source (AGENTS.md § Event IDs are localStorage keys).

Every file is written to a sibling .tmp-* and renamed into place, body before metadata, so an interrupted run leaves a stray temp file rather than a truncated snapshot or metadata describing bytes that were never stored. Those temp files are gitignored: refresh.yml commits the whole directory, so otherwise a run killed mid-write would pin a half-page in git forever.

Three reasons this is committed rather than cached:

• Re-parsing never re-fetches. Iterating on a parser reads these files, not the wikis (AGENTS.md § Scraping conduct).
• A refresh is reviewable. The commit diff is the page diff, so "an event vanished" is a question you can answer from git rather than from a wiki that has since changed again.
• The build stays offline. bun run build:feed parses whichever of these exists and falls back to fixtures/ otherwise, so a clean checkout and the container build work with no network.

The .state.json files track transient check attempts and failure streaks. When a source is confirmed (200 or 304), lastConfirmedAt is recorded in <source-id>.meta.json so downstream builds (including GitHub Pages, which deploys from git without access to the Gitea Actions cache) know the exact time the source was confirmed current.

The metadata is also rewritten on an unchanged page when the server rotates an ETag or Last-Modified while serving the same bytes. Keeping the old validator would mean sending a stale If-None-Match forever and being served the whole page every cycle, so that diff is worth the commit — contentChangedAt and the body stay put, so it is still visibly not a content change.

Fixtures are not the same thing. A fixture is pinned to a date and kept forever as the regression test for a page shape; a snapshot is the current page and is overwritten each time it changes.