diff --git a/C-progress.md b/C-progress.md
index 90136d1..67c7d49 100644
--- a/C-progress.md
+++ b/C-progress.md
@@ -3,7 +3,40 @@
 *Status: **v1 complete & verified**. Standalone interiors library + test page. Every shop door opens
 into a unique, seeded, themed interior, generated on demand in ~4ms, byte-identical every revisit.*
 
-Last updated: 2026-07-16 (round 20) · owner: PROCITY-C · reviewer: Fable
+Last updated: 2026-07-16 (round 21) · owner: PROCITY-C · reviewer: Fable
+
+---
+
+## Update 2026-07-16 (round 21, v4.0-beta close) — the five-town density door-soak (ledger #3)
+
+R21 §Lane C (wave 2 — ran **after A's venue cluster-adjacency bias** landed, `110c828`, so the soak reads the
+relocated world + A's re-pinned goldens). The carried R20 #6: **every one of the five beta towns at its new
+density**, deterministically sampled ~25 doors/town — the sample takes **one of every type present** then
+stride-fills, so the texture classes' first real appearance (milkbar/dept/stall on real shops) is always covered.
+
+| town | shops (in plan) | sampled | venues | types (all sampled) | throws | carves | path-fails | over-budget | worst draws |
+|---|---|---|---|---|---|---|---|---|---|
+| `katoomba_real` | 72 | 25 | 3 | 10 | 0 | 0 | 0 | 0 | **157** |
+| `newtown_real` | 67 | 25 | 3 | 11 | 0 | 0 | 0 | 0 | 155 |
+| `fremantle_real` | 79 | 25 | 3 | 11 | 0 | 0 | 0 | 0 | 153 |
+| `bendigo_real` | 35 | 25 | 3 | 10 | 0 | 0 | 0 | 0 | 154 |
+| `castlemaine_real` | 23 | 23 (all) | 3 | 8 | 0 | 0 | 0 | 0 | 156 |
+
+**123 doors · 0 throws · 0 carves · 0 path-fails · 0 over-budget · worst 157 draws (≤350).** In every town
+`typesInTown === typesSampled` — every archetype present was entered, including all three venue kinds
+(pub/band_room/rsl) and the texture classes. **All five towns landed 3 venues** → A's cluster bias + district
+placement hold at density.
+
+**§6 mapping verified live (John's SUBTLE directive, working by construction):** katoomba's cache is **20
+heroes + 60 texture** — exactly E's 3× cap, heroes untouched. In-plan (after A's counted drops): 17 heroes
+(opshop 10 · book 4 · record 2 · video 1) + 52 texture (milkbar 29 · dept 18 · stall 5) + 3 venues = 72.
+The texture classes' **first real appearance** renders right: **"Blue Mountains Chocolate Company"** — a real
+Katoomba `shop=chocolate` — now wears `milkbar` (70s geo wallpaper, cube shelves of price-tagged goods, counter,
+wall rack): a believable confectionery counter shop. The widening reads as texture, not takeover.
+
+*(Cache→plan deltas — e.g. katoomba 80→72 — are A's overflow/fragmentation drops, counted by cause in A's R20
+accounting; not an interior concern, and every surviving door builds clean.)* **C→F: density verdict GREEN.**
+Docs-only. C otherwise on-call; my §6 mapping + this soak close both C items for the beta.
 
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