feat(simulation): wire L3->L4 GenerateSkeleton dispatch (T-1022)

The Layer-4 quarter-skeleton geometry (D-234: morphology-correct streets +
the D-234b waterfront rule) was fully implemented but dormant — no
production call site dispatched GenerateSkeleton from a settlement
placement, so founding_orientation stayed pinned to the
context_from_read_set Cardinal stub.

Expand the BodyAnalyzed arm of drain_generation_completions to, before
caching the body, submit one GenerateSkeleton per CityPlacement: build the
D-199 context from the read-set, override founding_orientation with the
attractor-matched value carried on the placement (D-213), and derive a
canonical namespace-isolated quarter_id from (world_seed, body, city)
(D-194/D-230) instead of the city_id*10 placeholder. Dispatch logic is
extracted into the pure build_skeleton_work_item helper for DB-free testing.

Reader + world seed are optional system params (mirrors serve_atlas_requests);
absent either, dispatch is skipped and the body is still cached. Empty
placements and per-placement read_set errors are handled (warn + skip).
Station/multi-source dispatch (Q-109) is out of scope — BodyAnalyzed only
fires on the planetary AnalyzeBody path.

Tests: orientation-override + canonical-quarter_id unit test and a
determinism/city-scoping test on the helper. Full lib suite green (1327).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/src/atlas/plugin.rs

@@ -11,12 +11,16 @@ use bevy_app::prelude::*;
 use bevy_ecs::prelude::*;
 use bevy_ecs::schedule::IntoScheduleConfigs;
 
+use crate::atlas::attractor_matching::CityPlacement;
 use crate::atlas::body_world_state::{BodyWorldStateCache, CACHE_CAPACITY};
-use crate::atlas::city_context_reader::CityContextReaderResource;
-use crate::atlas::gen_queue::{GenCompletion, GenerationQueue};
+use crate::atlas::city_context_reader::{
+    context_from_read_set, CityContextReaderResource, CityEconomicReadSet,
+};
+use crate::atlas::gen_queue::{GenCompletion, GenPriority, GenWorkItem, GenerationQueue};
 use crate::atlas::layer_proxy::{handle_atlas_request, AtlasLayerResponse, AtlasLayerStatus};
 use crate::atlas::source_resolver::BodySourceResolverResource;
 use crate::bridge::{AtlasRequestBuffer, AtlasResponseBuffer};
+use crate::seed::{SeedChain, SeedDomain};
 use crate::simulation::rng::SimRng;
 use crate::simulation::time::SimulationTime;
 use crate::tick_phases::TickPhase;
@@ -78,10 +82,44 @@ fn serve_atlas_requests(
 fn drain_generation_completions(
     queue: Res<GenerationQueue>,
     mut cache: ResMut<BodyWorldStateCache>,
+    city_reader: Option<Res<CityContextReaderResource>>,
+    rng: Option<Res<SimRng>>,
 ) {
     for completion in queue.drain_completions() {
         match completion {
-            GenCompletion::BodyAnalyzed { state, .. } => cache.insert(state),
+            GenCompletion::BodyAnalyzed { state, .. } => {
+                // L3→L4 dispatch (T-1022, D-234): without a production call site the
+                // Layer-4 quarter skeleton never runs — morphology-correct streets and
+                // the D-234b waterfront rule stay dormant and `founding_orientation` is
+                // stuck at the `context_from_read_set` Cardinal stub. Submit one
+                // GenerateSkeleton per placed settlement, threading the attractor-matched
+                // orientation (D-213). Needs the city-context reader + world seed; absent
+                // either (e.g. unit tests), skip dispatch and just cache the body.
+                if let (Some(city_reader), Some(rng)) = (city_reader.as_ref(), rng.as_ref()) {
+                    let reader = &city_reader.0;
+                    let world_seed = rng.seed();
+                    let body_id = state.body_id.clone();
+                    for placement in &state.placements {
+                        let read_set = match reader.read_set(placement.city_id, world_seed) {
+                            Ok(rs) => rs,
+                            Err(e) => {
+                                tracing::warn!(
+                                    city_id = placement.city_id,
+                                    body_id = %body_id,
+                                    error = %e,
+                                    "L3→L4 dispatch: read_set failed — skipping placement"
+                                );
+                                continue;
+                            }
+                        };
+                        queue.submit(
+                            build_skeleton_work_item(&body_id, world_seed, placement, read_set),
+                            GenPriority::Low,
+                        );
+                    }
+                }
+                cache.insert(state);
+            }
             GenCompletion::Failed { item, reason } => {
                 tracing::warn!(?item, %reason, "background generation work item failed");
             }
@@ -118,11 +156,57 @@ fn drain_generation_completions(
     }
 }
 
+/// Build the Layer-4 `GenerateSkeleton` work item for one settlement placement
+/// (T-1022, D-234). Builds the D-199 context from the read-set (mirroring
+/// [`build_context`](crate::atlas::city_context_reader::CityContextReader::build_context),
+/// which is just `read_set` + `context_from_read_set`), then overrides the
+/// `Cardinal` stub with the attractor-matched
+/// [`FoundingOrientation`](crate::simulation::generator::FoundingOrientation) carried
+/// on the placement (D-213), and derives the canonical, namespace-isolated
+/// `quarter_id` from `(world_seed, body, city)` (D-194/D-230) — replacing the
+/// `city_id * 10` placeholder. Pure (no queue/cache access) so it unit-tests
+/// without a `systems.db`.
+fn build_skeleton_work_item(
+    body_id: &str,
+    world_seed: u64,
+    placement: &CityPlacement,
+    read_set: CityEconomicReadSet,
+) -> GenWorkItem {
+    // The D-199 raw fields ride alongside the context (generate_quarter_skeleton
+    // takes them separately), so capture them before context_from_read_set consumes
+    // the read-set.
+    let economic_role = read_set.economic_role.clone();
+    let population = read_set.population;
+    let founding_age_years = read_set.founding_age_years;
+
+    let mut context = context_from_read_set(placement.city_id, read_set);
+    context.founding_orientation = placement.founding_orientation.clone();
+
+    // Canonical quarter id (D-194/D-230): deterministic + namespace-isolated per
+    // (world_seed, body, city). SeedChain is Copy, so `chain.seed()` leaves `chain`
+    // usable for the work item's own field.
+    let chain = SeedChain::for_body(world_seed, body_id)
+        .derive(SeedDomain::Layer4Quarter, placement.city_id);
+    let quarter_id = chain.seed();
+
+    GenWorkItem::GenerateSkeleton {
+        city_id: placement.city_id,
+        body_id: body_id.to_string(),
+        context: Box::new(context),
+        quarter_id,
+        chain,
+        economic_role,
+        population,
+        founding_age_years,
+    }
+}
+
 #[cfg(test)]
 mod tests {
     use super::*;
     use crate::atlas::gen_queue::{GenPriority, GenWorkItem};
     use crate::seed::SeedChain;
+    use crate::simulation::generator::FoundingOrientation;
     use bevy_ecs::schedule::Schedule;
     use std::time::Duration;
 
@@ -212,4 +296,91 @@ mod tests {
         // The request buffer was drained.
         assert!(world.resource::<AtlasRequestBuffer>().0.is_empty());
     }
+
+    fn sample_read_set() -> CityEconomicReadSet {
+        use crate::simulation::generator::SettlementClass;
+        CityEconomicReadSet {
+            economic_role: "service_mixed".to_string(),
+            prosperity_baseline_bps: 6_000,
+            population: 500_000,
+            dominant_faction: None,
+            founding_age_years: 200,
+            settlement_class: SettlementClass::PopulationBudget,
+        }
+    }
+
+    fn sample_placement(city_id: u64, orientation: FoundingOrientation) -> CityPlacement {
+        use crate::simulation::generator::{ArrangementPattern, AttractorType, PoliticalArchetype};
+        CityPlacement {
+            city_id,
+            position: (10, 20),
+            attractor_type: AttractorType::CoastalAccess,
+            score: 100,
+            synthetic: false,
+            political_archetype: PoliticalArchetype::Commission,
+            arrangement_pattern: ArrangementPattern::RadialCore,
+            founding_orientation: orientation,
+        }
+    }
+
+    #[test]
+    fn build_skeleton_work_item_threads_orientation_and_canonical_quarter_id() {
+        let placement = sample_placement(
+            7,
+            FoundingOrientation::Coastal {
+                facing_degrees: 270,
+            },
+        );
+
+        let GenWorkItem::GenerateSkeleton {
+            city_id,
+            body_id,
+            context,
+            quarter_id,
+            economic_role,
+            population,
+            founding_age_years,
+            ..
+        } = build_skeleton_work_item("PlanetX", 42, &placement, sample_read_set())
+        else {
+            panic!("expected GenerateSkeleton");
+        };
+
+        // The attractor-matched orientation replaces the context_from_read_set
+        // Cardinal stub — the whole point of T-1022.
+        assert_eq!(
+            context.founding_orientation,
+            FoundingOrientation::Coastal {
+                facing_degrees: 270
+            }
+        );
+        assert_eq!(city_id, 7);
+        assert_eq!(body_id, "PlanetX");
+        assert_eq!(economic_role, "service_mixed");
+        assert_eq!(population, 500_000);
+        assert_eq!(founding_age_years, 200);
+
+        // quarter_id is the canonical D-194/D-230 derivation, not the city_id*10 stub.
+        let expected = SeedChain::for_body(42, "PlanetX")
+            .derive(SeedDomain::Layer4Quarter, 7)
+            .seed();
+        assert_eq!(quarter_id, expected);
+        assert_ne!(quarter_id, 7 * 10, "must not be the old placeholder");
+    }
+
+    #[test]
+    fn quarter_id_is_deterministic_and_city_scoped() {
+        let qid = |city_id: u64| {
+            let placement = sample_placement(city_id, FoundingOrientation::Cardinal);
+            let GenWorkItem::GenerateSkeleton { quarter_id, .. } =
+                build_skeleton_work_item("BodyA", 99, &placement, sample_read_set())
+            else {
+                unreachable!()
+            };
+            quarter_id
+        };
+        // Same inputs → same id; different city → different id.
+        assert_eq!(qid(3), qid(3));
+        assert_ne!(qid(3), qid(4));
+    }
 }