1@README.md
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3## Notes for agents
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5**Measure after the song, rescore after measuring.** A `measured:` line holds only for the `song.js` whose hash it records; after editing a song, run `nix run .#measure -- --song <theme>/<song> --write`, then `op-env-run -- node tools/critic/critic.mjs --write --all --song <theme>/<song>`, and commit both with the song.
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7**Jev stays unreachable in the measuring tab.** The relay is blocked with `page.route` so the fallbacks play and the numbers describe the song as written. Don't let a measurement call Jev: it would measure one arrangement among many and spend the site's key.
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9**Never a listener's tab.** Measuring tabs are headless and pinned to `?session=measure-<pid>-N`, unique per run.
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11**Edits are surgical.** Only the `measured:` line is written (`setMeasured` in `website/src/jev/measured.mjs`), the same way `tools/critic` rewrites only its own lines.
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13**Sections are the song's cadence, not its form.** A section is `.every(N)` cycles as written with Jev unreachable, so it matches the song's sections only where the fallback form changes on that cadence. Compare a spec's section promises against the keys the song's form actually uses (its `walk` fallbacks), not every key in order.
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15**The critic and the page read section totals only.** If you add a field to sections, decide whether `withoutSectionParts` (measured.mjs) and `measuredMix` (critic.mjs) should carry it: both keep the critic's prompt and every page small.