split nimmerworld architecture: phase 1 of 3 — vertical-by-domain directories Create 9 domain directories under nimmerworld/, each owning an architecture.md that will eventually sit alongside server/client/schema/test code for that domain (vertical-by-domain rather than horizontal-by-language).

runtime-engine/architecture.md

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+# Runtime Engine
+
+> *How scenes execute mechanically: the lemniscate as relaxation-step operator; slot-tokens with verifier-flags carrying the loop-state; phase-locked overlay-loops broadcasting at axis-rate; the v0.7 gesture-alignment-recursive-lemniscate that integrates player gestures into typed trait-vector summaries; emergent zones as the dramatic-episode unit with distributed funding and ternary trait-axis goal-evaluation; zone taxonomy and spawn-cadence.*
+>
+> ***Status: skeleton — content migration scheduled for commit 2 of the split-into-domains operation. Architecture content currently lives in `architecture-broad.md` and will land here next.***
+>
+> *Companion to: `architecture-broad.md` (executive summary + global meta-lists), `narrative-composition/architecture.md` (Compositor consumes the typed trait-summaries this engine emits), `player-experience/architecture.md` (gesture-circle is the player-input substrate that this engine integrates), `topology-and-rendering/architecture.md` (zones live on the rail+grid topology), `identity-and-personhood/architecture.md` (slot-tokens carry trait-vectors).*
+
+## Sections that will land here
+
+- §Core inversion — zones replace bubbles
+- §Zone anatomy
+- §Zone kinematics — the lemniscate runtime (incl. v0.7 gesture-alignment-as-recursive-lemniscate)
+- §Zone taxonomy (v1 starter set)
+- §Zone spawn cadence
+- §Emergent zones — the dramatic-episode unit
+
+---
+
+**Version:** 0.7.0-skeleton | **Created:** 2026-04-26 | **Updated:** 2026-04-26 | **Origin:** Skeleton placeholder for commit 1 of the split-into-domains operation