Arco Atlas
An interactive library of 4,883 graded violin works, live at atlas.arco.app (repertoire.arco.app redirects there). Created by Daniel Kurganov as a companion to the Arco practice app.
Pushing to main deploys to production on Vercel.
Develop
npm install
npm run dev
The advisor needs ANTHROPIC_API_KEY (in .env.local locally, and in the Vercel project settings for production).
Data
The catalogue comes from the "Violin Repertoire Finder" Google Sheet. After refreshing the snapshot in data/source/all-repertoire.json, rebuild the site data:
npx tsx scripts/build-data.ts
This writes public/data/catalogue.json, data/build/catalogue.json and the advisor's catalogue in lib/advisor/catalogue-text.ts. Commit the results and push.
The chamber music section (/chamber; how it was built: docs/chamber-music-plan.md) keeps its works in data/chamber/works.json. After editing them, check and rebuild its data; the build takes composer details and the works listed in both sections from the violin catalogue, so it runs after build-data.ts:
npx tsx scripts/chamber/check.ts
npx tsx scripts/build-chamber.ts
This writes public/data/chamber.json, data/build/chamber.json and the chamber advisor's catalogue (lib/advisor/chamber-catalogue-text.ts). lib/chamber/launch.ts is the launch switch: the section is public (in the instrument switcher, the sitemap and composer pages, indexed) unless NEXT_PUBLIC_CHAMBER_LIVE=0 hides it again.
Other scripts in scripts/ (recordings, character tags, popularity) call the Claude API and are run occasionally, not on every build.
Recording rule: the site never embeds a YouTube recording by Ray Chen, Sarah Chang, Joshua Bell or Stefan Jackiw; the builds fail on one and the judging scripts drop such candidates (docs/recording-rules.md).
The expansion of October 2026 (about 900 works for 52 composers) was produced with the tools in scripts/expand/; what changed, what was left out and how it was checked is written up in docs/catalogue-expansion-2026-10.md.
The technical-materials expansion that followed (about 900 scale systems, exercise books, étude and caprice books, including every study of Kreutzer, Rode, Dont Op. 35, Fiorillo and Gaviniès) was researched by subagents and graded blind by two models; method, decisions and caveats are in docs/technical-materials-2026-10.md, and data/expansion/tech/NOTES.md says how to re-run it (data/expansion/tech/regen.sh).
The modern and contemporary expansion that followed (about 820 works by 182 twentieth-century and living composers, including Philip Glass, Arvo Pärt and Augusta Read Thomas) was researched by subagents and graded blind by two models; see docs/modern-contemporary-2026-10.md (data/expansion/modern/regen.sh re-runs it).
Where Arco appears on the site (piece-page line, footer, return-visit card, iOS banner) and how its links are tagged: docs/arco-touchpoints.md.
IMSLP links: every work that has an IMSLP page links to it (3,093 of 4,883), and there is no search fallback; what was done and how to extend it is in docs/imslp-links-2026-10.md. npx tsx scripts/check-imslp.ts --live re-verifies every link.
Addresses of pieces that were merged or renamed keep working through data/id-redirects.json and data/slug-redirects.json (read by next.config.ts; scripts/expand/redirects.ts regenerates them).
