Fable: frontier 2b/2c — THE HORIZON MATTE + VORONOI OUTSKIRTS (from the Lague video review; engine path rejected, shader tricks adopted)

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

docs/THE_FRONTIER.md

@@ -81,7 +81,20 @@ Candidates, ranked by honest cost:
    epoch with an alpha/beta/close arc of its own, not a round.
 2. **Sky / cloud domes — cheap, near-term (v6/v7 polish).** Skies are baked textures today; a
    seeded FBM dome gives every day its own weather-shaped sky, composes with the existing
-   weather states, and is one lane's item (B, lighting).
+   weather states, and is one lane's item (B, lighting). *(2026-07-23: Sebastian Lague's
+   graphics-library video §6 is effectively the implementation guide — fBm + cheap
+   Rayleigh/Mie approximation in one full-screen pass; the winmap shader proves the house
+   does this class of trick. Skip full volumetric raymarch until measured.)*
+   - **2b. THE HORIZON MATTE (filed 2026-07-23, from the same video) — the poor-man's
+     terrain.** Towns end at a flat empty horizon. A seeded fBm-raymarched HORIZON BAND — a
+     matte painting that computes itself, ~1 draw, zero geometry — puts the Blue Mountains
+     behind Katoomba and scrub ranges behind Bendigo, seeded per town (real towns could bias
+     the profile from their actual region). Buys most of the terrain epoch's FEEL years early;
+     classic-gated like everything; retires automatically if real terrain ever lands.
+   - **2c. VORONOI OUTSKIRTS (same filing).** Grid-constrained Voronoi paddocks with treeline
+     borders as the town-edge ring, so the approach to town reads as countryside instead of a
+     hard stop. A's partitioner class (plan-side, seeded, golden-aware) + B's tree instancing.
+     Pairs with 2b; both are candidates for a single "THE HORIZON" polish round.
 3. **Wear & grime — cheap, high-charm (E/C canvas painters).** Seeded value-noise for sleeve
    ring-wear, facade sun-fade, footpath staining — per-item, deterministic, and exactly the
    90s patina the parody sleeves deserve. Pairs with the beta's price-guide work (a worn