Record NPC sourcing decision and crowd prototypes

MEMORY.md

@@ -4,16 +4,22 @@ Session memory for durable decisions, state, and gotchas. Keep concise, remove o
 
 ## Decisions
 
-- **NPC model sourcing research (2026-11-03):** `docs/npc-model-sourcing.md` evaluates
-  Quaternius Ultimate Modular (CC0), Kenney Blocky Characters (CC0), Khronos
-  CesiumMan/RiggedFigure (CC-BY 4.0) and the MakeHuman base mesh (CC0). No download is a
-  drop-in: every source lacks the `npc_base` node, the 13 contract bones and the five tint
-  slots; Quaternius additionally exceeds the vertex budget (10.5k–13k imported) and uses a
-  62-bone T-pose rig, CesiumMan/RiggedFigure are short technical references, and the
-  MakeHuman base is ~19k verts with no rig. Downloaded files stay under
-  `tmp/npc-research/` (gitignored), with SHA-256 provenance in the doc. The direction is
-  pending owner review; default if unreviewed is procedural expansion. Do not commit or
-  ship an external model before the licence/ADR decision.
+- **NPC model variety decision (2026-11-03, ADR-0015):** CC0 is acceptable for shipped
+  assets; CC-BY only with attribution in `CREDITS.md`; no service assets with redistribution
+  restrictions. The **procedural generator is the primary path**. Four crowd-variety specs were
+  prototyped with the existing builder (`npc_crowd_a` bun/slim/sunglasses, `npc_crowd_b`
+  bald/broad/beard/shoulder bag, `npc_crowd_c` coat/umbrella, `npc_crowd_d` hood/cup); all audit
+  clean at 4,550–5,258 tris / 4,356–5,086 verts. Prototype assets stay in
+  `tmp/npc-research/generator_proto/`; do not add them to the 0.10.0 release candidate.
+  **Quaternius is a reference, not a shipped base:** welding brings `Casual_Hoodie` from 12,518
+  to 3,199 verts and a 0.75 decimate to 2,423 verts / 4,654 tris, and its Idle/Walk clips read
+  well, but the T-pose 62-bone realistic rig/proportions do not match the arm-down 13-bone
+  contract. A contract rebuild is a no-go without a body proportion warp; a second
+  rig/animation path needs its own ADR. **MakeHuman is deferred** to a separate local pipeline:
+  the CC0 base is 19,158 verts / 36,972 tris and decimates to 3,780 / 6,468 at 0.35, but needs
+  retopology, a custom rig and project clothing. Research previews are committed under
+  `docs/blender_previews/sheet_npc_{sources_research,crowd_prototypes}.jpg`; the CC-BY entries
+  (CesiumMan/RiggedFigure, © Cesium) are attributed in `CREDITS.md` and are development-only.
 
 - **0.10.0 balance protocol:** `docs/balance-acceptance.md` defines targets and
   denominator/cohort rules for the 36 venue/difficulty/phase cells, seeds 1–100,