Epic 5 Phase 2.3 — instrument Assembly for measurement

Gallery, metadata, scene-gate and scene-sweep now handle kind:'model'
with a deterministic ActorSpec. Drawing uses a forked ActorGenerator
so the actor stream never shifts the identity/palette streams:
  gallery.renderScene → generateActor per context for model stages
  metadata.measureLibrary now includes model stages, SCHEMA 5,
    fingerprint covers actors/
  scene-gate.runSceneGate → alive/animates/deterministic/distinct/
    param-sweep/flash-rate all drive Engine.setLayerSpecs with
    actorSpec, and consumes: searches re-derive the actor for the
    swapped identity (so the consumes: gate is still testable).
  scene-sweep behaves the same per-cell.
  Engine.setLayerSpecs now forwards actorSpec/framing into createLayer
    so the checks don't need ArcDriver.

SCHEMA bump 4→5 forces metadata refresh on next gallery build,
which is intentional: model stages now participate. Gates remain
all green (69 scenes) and vite builds clean — no runtime change to
the render path for fragment stages.

Co-Authored-By: Claude <noreply@anthropic.com>

flow-state/src/checks/gallery.js

@@ -27,6 +27,7 @@ import { describeIdentity } from '../look/Identity.js';
 import { frameDescriptor, motionDescriptor } from './variety/descriptors.js';
 import { frameLuminance, frameVariance } from '../engine/hash.js';
 import { descriptorDistance, STRUCTURAL } from './variety/signature.js';
+import { generateActor } from '../actors/ActorGenerator.js';
 
 const THUMB = { width: 256, height: 144 };
 
@@ -89,6 +90,11 @@ export function renderScene(engine, module, contexts) {
 
         const rng = new Rng(hashString(`${module.name}:${ctx.name}`));
         const params = sampleValues(module, rng, ctx.bias, ctx.personality.temperament);
+        const actorRng = new Rng(rng.fork(`actor:${module.actor || 'model'}`).seed);
+        const summary = ctx.track.summary;
+        const actorSpec = module.kind === 'model' && module.actor
+            ? generateActor({ summary, rng: actorRng, archetype: module.actor, personality: ctx.personality, identity: ctx.personality.identity })
+            : null;
 
         engine.setLayerSpecs([{
             module,
@@ -98,6 +104,7 @@ export function renderScene(engine, module, contexts) {
             blend: 'normal',
             palette: ctx.palette,
             personality: ctx.personality,
+            actorSpec,
         }]);
         engine.compositor.reset();
         // A few frames of warm-up so anything with state is past its first frame.
@@ -181,7 +188,7 @@ export function renderScene(engine, module, contexts) {
 export async function buildGallery({ contexts, onScene, only = null } = {}) {
     const list = only
         ? scenes.filter((m) => only.includes(m.name))
-        : scenes.filter((m) => m.kind === 'fragment');
+        : scenes.filter((m) => m.kind === 'fragment' || m.kind === 'model');
 
     const engine = new Engine({ ...THUMB });
     const rows = [];