docs: TDTL v2 body, shelf-edge variation, erosion deferred (terrain-water task 10)

BLUEPRINT_FORMAT.md: TDTL rewritten for the v2 body (30 B) with the
version-skip rule spelled out -- this is the one section whose body is
VERSIONED rather than extended, because v1's layout was retired rather
than grown, and a reader that guesses would mint plausible nonsense.
Records edgeAmpM as APPLIED (post-clamp), so the file always describes
the terrain rather than the request. Config-knobs section updated:
ShelfEdgeVariation is metres of INPUT height -- a boundary displacement,
not an elevation.

Tools/Scripts/README.md: the two detail passes and why neither can breach
the red ceiling or the 420 m cap (K2/K6 do not move). Adds an explicit
"no rivers, no erosion, no flow routing anywhere in this pipeline" note
with the reverted D8 pass and its lesson on the record, so the next
reader does not re-derive it.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Core/Scripts/BLUEPRINT_FORMAT.md

@@ -56,7 +56,7 @@ Every section: `[u32 tag][u64 payload-length in bytes][payload]`.
 | `BIOM` / `0x4D4F4942` | `MapSize²` × `u8` biome ordinal, same pixel order | Mandatory. Ordinals from `Enums.cs::Biome` — **append-only, never reorder** (the ordinal IS the wire value). Writer refuses ordinals > 255; reader rejects ordinals ≥ the known biome count (parse-time validation; the palette's runtime Dirt fallback for in-memory values is unchanged). Length must equal `MapSize²`. |
 | `TOWN` / `0x4E574F54` | `i32 count`, then per town: `f32 X` · `f32 Y` · `u8 tier` · `u8 isHighwayNode` (0/1) | Tier ordinals from `Enums.cs::TownTier`, append-only, range-checked on read. The highway-node flag is what the generator's road topology was built from (v1 dropped it); carried and exposed on the parsed blueprint, consumed by nothing server-side yet. |
 | `TCRV` / `0x56524354` | 50 B base: `u16 curveVersion` · `f32 knot1..knot4` · `f32 spikeMax` · `f32 sea` · `f32 orangeCeil` · `f32 redCeil` · `f32 benchLo` · `f32 benchHi` · `f32 peakCap` · `f32 tailSlope`. **When `curveVersion ≥ 4`, a 36 B modulation extension follows:** `f32 benchAmp` · `f32 plateauAmp` · `f32 shelfSpanMin` · `f32 shelfSpanMax` · `f32 elevFreqIslands` · `f32 strengthFreqIslands` · `i32 benchSeedOffset` · `i32 plateauSeedOffset` · `i32 strengthSeedOffset`. **When `curveVersion ≥ 5`, a 9 B preset extension follows:** `u8 presetId` (1 = compact, 2 = balanced) · `f32 k5` · `f32 k6` — with the four base knot slots this makes the effective curve unambiguous from the record alone (record total 95 B; the length-framed section + version byte keep every layout change safe) | Optional — present iff the height-redistribution curve shaped this blueprint's `HGTS` (config `TerrainCurve: "v3"`); absent = raw legacy profile. **The `u16 curveVersion` selects the field semantics and the unserialized anchor set:** v1 — knots t1..t4, spikeMax = pooled calibration max, benchLo/Hi = the 50 m plateau's lo/hi. v2 — as v1 but spikeMax = the seed's effective raw pre-curve maximum (per-seed spike normalizer). v3 — knots = K1..K4 of six (K5 = 0.930304, K6 = 1.050720 are version constants, not serialized), spikeMax per-seed, benchLo/benchHi = the fixed 100 m / 220 m shelves. **v4 (current)** — as v3, but benchLo/benchHi are the shelf **BASE** anchors and the extension record carries the spatial-modulation parameters: shelf elevations vary ±benchAmp/±plateauAmp and shelf strength blends the output span across `[shelfSpanMin, shelfSpanMax]`, via Simplex fields seeded `resolvedWorldSeed + seedOffset` at `freq/MapSize` (frequencies stated in undulations per island width). Because spikeMax is per-seed (v2+), blueprints are not reproducible from curve constants alone — that is why it is recorded. **Metadata only:** exported heights are already curved; nothing re-applies the map. Calibration provenance: `HeightCurve.cs` header + the task-05/06/07 reports. |
-| `TDTL` / `0x4C544454` | 38 B: `u16 detailVersion` · `f32 reliefAmpM` · `f32 reliefFreqIslands` · `f32 incK` · `f32 incP` · `f32 incCapM` · `f32 seaClampRaw` · `f32 craterExclFactor` · `f32 shelfIncWeight` · `i32 reliefSeedOffset` | Optional — present iff the terrain detail passes shaped this blueprint's `HGTS` (config `TerrainDetail: "v1"`, requires the curve): shelf micro-relief (±reliefAmpM, shelf-ness weighted) and D8 drainage incision (`depth = K·accum^p·slope`, capped, riser-masked, sea+1 m clamped, crater-excluded). **Metadata only** — heights are already detailed; the incision channels are the designated future river routes (Phase C). Machinery: `Tools/Scripts/TerrainDetailPass.cs`. |
+| `TDTL` / `0x4C544454` | 30 B: `u16 detailVersion` · `f32 reliefAmpM` · `f32 reliefFreqIslands` · `i32 reliefSeedOffset` · `f32 edgeAmpM` · `f32 edgeFreqIslands` · `i32 edgeSeedOffset` · `f32 edgeMaxShiftM` | Optional — present iff the terrain detail passes shaped this blueprint's `HGTS` (config `TerrainDetail: "v1"`, requires the curve). **`detailVersion` selects the body layout and a reader that does not recognise it SKIPS the section** (leaving detail metadata null) rather than misreading a differently shaped payload — the one section whose body is versioned rather than extended, because v1's layout was retired rather than grown. **v1 (retired, never shipped)** — shelf micro-relief + D8 drainage incision, 38 B; the incision produced grid-aligned artifacts and was reverted whole, so the only v1 payloads that exist are in that batch's own tree. **v2 (current)** — shelf micro-relief (±`reliefAmpM` output metres, shelf-ness weighted) + shelf-edge variation: a per-column shift of the curve's shelf/riser knot block K3/K4/K5, drawn from a Simplex field seeded `resolvedWorldSeed + edgeSeedOffset` at `edgeFreqIslands/MapSize`, amplitude ±`edgeAmpM` **metres of INPUT height** — a displacement of the shelf boundary contour, not an elevation change. `edgeAmpM` is recorded **as applied**, after the clamp to `edgeMaxShiftM` (the preset's band-squeeze bound), so the record always describes the terrain rather than the request. **Metadata only** — heights are already detailed. Machinery: `Tools/Scripts/TerrainDetailPass.cs`. |
 | `WBID` / `0x44494257` | `MapSize²` × `u16` water-body id, same pixel order as `HGTS` | Optional (absent = no water data, e.g. a legacy re-encode). `0` = no water, `1` = **the** ocean body, `2..N` = lakes. Ids assigned in deterministic scan order (X outer / Y inner, first-encountered pixel), lakes labeled with the **same 4-connectivity as `CalculateTrueOcean`**. Membership is exactly the generator's water classification — the biome grid's Ocean/Lake pixels and this grid's nonzero pixels are the same set **by construction** (shared predicates). Length must equal `2·MapSize²`. |
 | `WBTB` / `0x42544257` | `i32 count`, then per body (20 B): `u16 id` · `u8 type` (0 ocean, 1 lake) · `u8 salinity` (0 fresh, 1 salt) · `f32 surfaceLevel` · `i32 pixelCount` · `f32 centroidX` · `f32 centroidY` | Optional, paired with `WBID`. **`surfaceLevel` is a documented TRANSITIONAL rule:** one flat level per body — `GetSeaLevel` at the body's pixel centroid (ocean: at the map centre) under the still-live latitude field; superseded by the flat-scalar sea model (minted, lands with the coast change set). The field's per-pixel slope is deliberately NOT baked into any section. **Salinity is a provisional default** (ocean salt, lake fresh) — a placeholder for the future fresh/salt irrigation mechanic, not a mechanic. |
 | `WSRF` / `0x46525357` | `MapSize²` × `u16` quantized water-surface elevation, same pixel order | Optional, paired with `WBID`. `0` is the reserved **no-water sentinel**; a real level `L` (raw height units) encodes as `1 + round(L × 32768)` so it can never encode to 0; decode `(q − 1)/32768` (`BlueprintFormat.EncodeWaterLevel`/`DecodeWaterLevel`). Covers `[0 … ~1.99997]` raw at `1/32768` raw ≈ **7.7 mm** of world height (1 raw = 251 m) — far finer than the 1 m voxel. Nonzero exactly where `WBID` is nonzero; the value is the pixel's body level. |
@@ -113,8 +113,11 @@ body).
   shelves at 100±12 m / 220±20 m, per-seed-normalized 420 m summit spires, 60 % lowland) shapes
   `HGTS`.
 - **`TerrainDetail`** (`"v1"` | `"off"`, default `"v1"`; no-op without the curve) — the task-10
-  detail passes as one judged unit: shelf micro-relief (`ShelfReliefAmp` metres, default 3) and
+  detail passes as one judged unit: shelf micro-relief (`ShelfReliefAmp`, default 3 m of output
-  drainage incision. When on, `TDTL` records the parameters. Biome/water classification is curve-invariant by
+  height) and shelf-edge variation (`ShelfEdgeVariation`, default 12 m of **input** height — how
+  far the shelf/riser boundary contour wanders, clamped at load to the preset's band-squeeze
+  bound, loudly). Both are output-height only. When on, `TDTL` records the parameters as applied.
+  Biome/water classification is curve-invariant by
   construction (it classifies the retained uncurved heights); town positions and everything 3D
   follow the curved terrain. When on, `TCRV` records the effective parameters including the
   per-seed `spikeMax`.

Tools/Scripts/README.md

@@ -19,10 +19,19 @@ Generates the entire 2D blueprint. Roughly in order:
    ring — and a per-seed-normalized summit spike to the 420 m cap) reshapes above-sea terrain
    after noise/falloff/Trench and before the crater carve; biome classification reads a
    retained uncurved map, so biomes are identical either way. With `TerrainDetail: "v1"` (the
-   default) two detail passes follow the curve: shelf micro-relief (±3 m rolling skin on the
+   default) two detail passes ride along with the curve (`TerrainDetailPass.cs`): shelf
-   benches/plateaus) and D8 drainage incision (rain-cut ravines in the risers — the future
+   micro-relief (`ShelfReliefAmp`, ±3 m rolling skin on the benches/plateaus) and shelf-edge
-   river routes; `TerrainDetailPass.cs`). Drops the `0_height` hillshade snapshot (hypsometric
+   variation (`ShelfEdgeVariation`, 12 m) — a per-column shift of the shelf/riser knot block that
-   bands × NW hillshade) in both modes.
+   makes the shelf edge scallop into notches, coves and peninsulas instead of tracing a clean
+   height contour. Both touch exported heights only, and neither can reach below the red ceiling
+   or above the 420 m cap: the curve's K2 and K6 knots do not move, so a warped column is
+   bit-identical to an unwarped one outside the shelf/riser stack. Drops the `0_height` hillshade
+   snapshot (hypsometric bands × NW hillshade) in both modes.
+
+   **No rivers, no erosion, no flow routing anywhere in this pipeline.** A D8 drainage-incision
+   pass was written and reverted in task 10 — per-cell steepest descent on a regular grid can only
+   route along eight headings, and at map scale that reads as straight hatching, not drainage.
+   Erosion is Phase C work: a hydraulic pass over final terrain, after the shape stops moving.
 3. **Sea level and water** — sea level per the configured model (`SeaLevelModel`: `"flat"` scalar
    — the default, `SeaLevelValue` 0.15 — or the legacy `"field"` latitude Lerp); flood fill
    separates true ocean from inland lakes; a mainland fill guarantees one contiguous landmass.