Docs: session log Part O — baked splat ground iteration

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Docs/Vault/07_Sessions/2026/2026-07-09_B4d_Tail_Collision_Grounding.md

@@ -304,6 +304,21 @@ carpets excluded from the flora cache entirely; flower drifts thinned determinis
 Wildflower+Sunflower 50%, center r<13 ×0.6 → 17/38 off) so the play/build area reads clear and flowers
 become ring accents.
 
+## Part O — ground iteration 2 (`4e1ea3ecb`): baked splat base + HP detail split
+
+Operator: "better but could be further improved." The remaining plainness was single-TEXTURE ground — noise
+only ever modulated brightness. Rebuilt as a **baked splat**: each biome gets a unique 1024 base map (CPU
+composite, ~7 s bake) blending real materials by fbm masks — meadow grass+dirt+clover, arid sand+sand2+dirt —
+with the worn paths, a congregation-wear disc at the storage crystal, an arena-wear disc at the room-quad
+centers, hue drift and the rim vignette all baked in. Fine texture moved to the DETAIL slot as a generated
+2048 high-pass (full − 128-blur, ×1.4, LINEAR) tiled 22×/26× — crisp up close, unique-splat identity at
+distance, zero macro repetition. Plane UV mapping probed exactly (u=0.5−x/90, BOTH axes inverted) so baked
+wear lands on the real landmarks. Superseded: the WornPath overlay quads + mat + tex DELETED (double-darkened
+over baked wear, caught fog as a ghost rectangle) and the old macro-noise textures DELETED. Biome-tint MPB +
+normals untouched. Ground luminance now 0.30/0.33 in edit ambient (tints stay the one-line brightness knob
+for the play lap). Recipe note: bake pattern = readback-blit sources to linear Color[] → composite →
+LinearToGammaSpace → PNG sRGB; HP detail imports LINEAR.
+
 ## Next-session intent
 
 **Phase 1.5b bundle 1 (ground) is SHIPPED**; remaining locked bundles in order: **2) decals** (explosion