diff --git a/Core/Scripts/BLUEPRINT_FORMAT.md b/Core/Scripts/BLUEPRINT_FORMAT.md
index 6c0da54..1ab1324 100644
--- a/Core/Scripts/BLUEPRINT_FORMAT.md
+++ b/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
-  drainage incision. When on, `TDTL` records the parameters. Biome/water classification is curve-invariant by
+  detail passes as one judged unit: shelf micro-relief (`ShelfReliefAmp`, default 3 m of output
+  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`.
diff --git a/Tools/Scripts/README.md b/Tools/Scripts/README.md
index 7b5b18a..0b941fa 100644
--- a/Tools/Scripts/README.md
+++ b/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
-   benches/plateaus) and D8 drainage incision (rain-cut ravines in the risers — the future
-   river routes; `TerrainDetailPass.cs`). Drops the `0_height` hillshade snapshot (hypsometric
-   bands × NW hillshade) in both modes.
+   default) two detail passes ride along with the curve (`TerrainDetailPass.cs`): shelf
+   micro-relief (`ShelfReliefAmp`, ±3 m rolling skin on the benches/plateaus) and shelf-edge
+   variation (`ShelfEdgeVariation`, 12 m) — a per-column shift of the shelf/riser knot block that
+   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.