Exhaustive analysis of two working AC clients revealing three critical
findings that reshape acdream's movement system:
1. Server-authoritative Z: neither AC2D nor holtburger computes local
terrain Z for the player. AC2D sends keys, receives position. Holtburger
dead-reckons for smoothing but the server overrides.
2. Terrain split formula mismatch: AC2D and ACViewer's render path use
0x0CCAC033-based FSplitNESW; WorldBuilder (our source) uses a different
214614067-based physics formula. Our terrain mesh triangulation doesn't
match the real AC client's, causing Z mismatches on slopes.
3. Movement deduplication: MoveToState sent once per state change, not per
frame. AutonomousPosition heartbeat every 1 second.
Also adds AC2D to CLAUDE.md reference repos section.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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