Lucas WintherandClaude Opus 5
286aadefc4
Every snapshot is written to a sibling `.tmp-*` and renamed into place, so a run killed mid-write leaves one behind. `refresh.yml` commits the whole snapshots/ directory, which would pin that truncated page in git forever — and the point of the atomic write was that a crash leaves nothing a reader can mistake for a page. Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
46 lines
2.8 KiB
Markdown
46 lines
2.8 KiB
Markdown
# Snapshots
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Raw pages, exactly as fetched. `scripts/refresh-sources.ts` writes them; nothing else fetches.
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```
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<source-id>.html the body verbatim — tracked
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<source-id>.meta.json hash, size, charset, ETag, Last-Modified, when the bytes last changed — tracked
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<source-id>.state.json when we last checked, and failure streak — gitignored
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```
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"Verbatim" means the bytes as served, not text we re-encoded. `charset` in the metadata records
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what those bytes are in — the `Content-Type` header, else a `<meta charset>` in the page, else
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UTF-8 — and `bytes` is the served length. A page in Shift_JIS or Latin-1 decoded as UTF-8 would be
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stored as a field of U+FFFD with the original bytes gone; re-parsing could never recover it, and the
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mojibake would reach `slugify`, moving every event ID for that source (CLAUDE.md § Event IDs are
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localStorage keys).
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Every file is written to a sibling `.tmp-*` and renamed into place, body before metadata, so an
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interrupted run leaves a stray temp file rather than a truncated snapshot or metadata describing
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bytes that were never stored. Those temp files are gitignored: `refresh.yml` commits the whole
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directory, so otherwise a run killed mid-write would pin a half-page in git forever.
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Three reasons this is committed rather than cached:
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- **Re-parsing never re-fetches.** Iterating on a parser reads these files, not the wikis
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(CLAUDE.md § Scraping conduct).
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- **A refresh is reviewable.** The commit diff is the page diff, so "an event vanished" is a
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question you can answer from git rather than from a wiki that has since changed again.
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- **The build stays offline.** `bun run build:feed` parses whichever of these exists and falls back
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to `fixtures/` otherwise, so a clean checkout and the container build work with no network.
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The `.state.json` files are the exception: they change every cycle whether or not a page did, and
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committing them would mean a commit per run saying nothing happened. CI keeps them in the actions
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cache instead: `refresh.yml` saves that cache, and `ci.yml` restores it read-only before building
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the feed. Both halves matter — `lastConfirmedAt` lives only there, and without the restore the feed
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falls back to `contentChangedAt` and the UI calls every source stale two days after its bytes last
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moved.
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The metadata is rewritten on an unchanged page in one case: the server rotating an `ETag` or
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`Last-Modified` while serving the same bytes. Keeping the old validator would mean sending a stale
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`If-None-Match` forever and being served the whole page every cycle, so that diff is worth the
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commit — `contentChangedAt` and the body stay put, so it is still visibly not a content change.
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Fixtures are not the same thing. A fixture is pinned to a date and kept forever as the regression
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test for a page shape; a snapshot is the current page and is overwritten each time it changes.
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