Backendless, read-only LibsSource that serves the full default symbol+footprint set from versioned immutable CDN snapshots. Each lib is an r2-idb-sync static origin opened as a one-layer SyncStack (1 bundle cold, 0 fetches warm, IDB-cached, offline) — the layer descriptor is built locally from lib id + tag, no resolve endpoint in the loop.
Wired via VITE_LIBS_SOURCE=cdn + VITE_LIBS_MANIFEST_URL; build-demo gains --lib-tag (points the demo at libs/kicad/<tag>/manifest.json; omitted keeps offline static). Unit-tested against a fake CDN built with the real encodeBundle/sha256Hex codecs, pinning the publish format.
Next: publish-libs.mjs (C1.2) emits this format over the full set; CI keyed by lib tag (C1.3).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
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