13-page A4 PDF reverse-engineered from current code: 4-stage serial pack
flow with 3 gates, intra-pack topo + 4-concurrency, L0-L3 derivation,
Seedance anchor priority, and spec-vs-implementation gap callouts.
Source HTML kept for future re-render via Chrome headless.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
