Built with Mojang Mappings + Loom 1.15 stack for MC 1.21.9 / 1.21.10 (with native Flashback 0.39.4 variant).

Validated end-to-end via autonomous test harness — record + merge + playback all pass on native 1.21.10 sources. Same merge code path as 1.21.11 (byte-identical stats on shared input data).