# Lab Report — The JavaScript of `play.html`: Layers, Traces, and the MUD Client **Original:** 2026-07-16 · subject `play.html` @ `43bd09c` (37,271 lines · `ENGINE_VER = 'coc-3.104.0'`) **Verified & rewritten:** 2026-08-21 (§DOC-02cj) against HEAD (38,712 lines) — 623 → 352 lines **Class:** structural read (whole-file code map). Four execution traces: boot, UI, movement, quest acceptance. --- ## Abstract The file is one `