fix(simulation): PR #179 review round — F1-F4

F1: T-1112 amendment touch-point list gains the ZoningType PartialOrd/Ord derive (mirroring DistrictType's T-994 precedent) so the dominant_zoning declaration-order tie-break is computable. F2: stale terminal-layer doc on AtlasLayerRequest.up_to corrected to Region. F3: believability cascade_for_body bumped to Region — harness mirrors production depth, invariant documented. F4: end-to-end dispatch coverage — populated-regions test asserts regions + second handle_atlas_request returns region_grid; no-params sibling asserts regions empty. Suites: layer_proxy 10, believability 4, gen_queue 8, cascade 10.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

server/src/atlas/layer_proxy.rs

@@ -31,8 +31,8 @@ const DEFAULT_SEA_LEVEL: f32 = 0.3;
 /// A client request for a body's generation layers (D-225).
 ///
 /// `up_to` is a forward-compat seam that is **not yet honored**: `run_work_item`
-/// (`gen_queue.rs`) currently runs the cascade through `CascadeLayer::RoadGraph`
-/// (the terminal layer, T-1038) unconditionally on every request, ignoring this
+/// (`gen_queue.rs`) currently runs the cascade through `CascadeLayer::Region`
+/// (the terminal layer, T-1113) unconditionally on every request, ignoring this
 /// field. Wiring per-request depth (and the partial caching it implies) is
 /// deferred to #1021.
 #[derive(Debug, Clone, Serialize, Deserialize)]
@@ -1104,7 +1104,11 @@ mod tests {
     }
 
     /// With body_params_reader wired, a cache miss enqueues an AnalyzeBody that
-    /// completes with populated `districts` (DistrictProfile layer ran).
+    /// completes with populated `districts` (DistrictProfile layer ran) AND
+    /// populated `regions` (Region layer ran — the production terminal,
+    /// T-1113). Then the completed state served back through
+    /// `handle_atlas_request` carries a `region_grid` — closing the full
+    /// dispatch → Ready → region_grid loop (PR #179 F4).
     #[test]
     fn body_params_reader_wired_produces_populated_regions() {
         let mut cache = BodyWorldStateCache::new(CACHE_CAPACITY);
@@ -1142,6 +1146,29 @@ mod tests {
             !body_state.districts.is_empty(),
             "districts must be populated when body_params_reader is wired (T-1032 dispatch path)"
         );
+        assert!(
+            !body_state.regions.is_empty(),
+            "regions must be populated when body_params_reader is wired (T-1113 dispatch path)"
+        );
+
+        // Serve the completed state back through the proxy: the cache-hit
+        // branch must build and include the region grid.
+        cache.insert(body_state);
+        let ready = handle_atlas_request(
+            &req("GJ1c"),
+            &mut cache,
+            &queue,
+            &resolver,
+            None,
+            Some(&params_reader),
+            42,
+            2,
+        );
+        assert_eq!(ready.status, AtlasLayerStatus::Ready);
+        assert!(
+            ready.region_grid.is_some(),
+            "a Ready response for a Region-populated body must carry region_grid"
+        );
     }
 
     /// Without body_params_reader (None), districts is empty — pre-T-1032 behaviour.
@@ -1181,5 +1208,10 @@ mod tests {
             body_state.districts.is_empty(),
             "districts must remain empty when no body_params_reader is wired"
         );
+        assert!(
+            body_state.regions.is_empty(),
+            "regions must remain empty when no body_params_reader is wired \
+             (the Region layer gates on body_params, T-1113)"
+        );
     }
 }