derive_chunk_context now derives channel_anchor_m and coast_anchor_m from
the Region-or-higher seed path (D-239 §10); all five voxel placement sites
measure distance to these anchors in continuous world coordinates:
- T-1040: compute_channel_state / compute_meander_reach_channel /
in_levee_band subtract the region anchor instead of measuring from the
world origin axis — active channels now exist in their chunks anywhere
on the body, continuous across chunk boundaries. has_active_channel is
honest in both directions (band-crossing gate; floor covers the
BraidedDelta belt at short wavelengths).
- T-1041: fjord/cliff/gorge/delta drop their rem_euclid(64) chunk-frame
folds — one valley/coastline/fan per region instead of one per chunk.
D-239 §9 chokepoint widths preserved; two i32 wall-rise overflows on
region-scale distances fixed by clamping before multiply.
Harness: 6 new believability tests (channel presence + gate honesty at
chunk (1000,-750), cross-boundary continuity, one-landform-per-region,
braid-belt confinement); drainage sweeps strengthened with anchor-band
chunks. Voxel golden regenerated deliberately: case A now pins a genuinely
in-channel Shallow voxel on the anchor, case C a Deep trough voxel
matching its label; case B byte-identical and L0/L1 cascade golden
untouched (no upstream leak). Review: approved, three minors addressed
(truncation-convention docs, delta gate floor, case C relocation).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
jpmschweitzerandClaude Fable 5
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