feat(simulation): wire region climate layer into the cascade + proxy (T-1113, D-243)

CascadeLayer::Region appended per the enum's append-only Ord rule (depends only on seed/body_params/heightmap dims — documented); BodyWorldState.regions BTreeMap per the districts precedent; RegionGridLayer dense row-major all-integer encoding (season/weather repr(u8) discriminants, mean_temp deci-degC i16 with i16::MIN airless sentinel, moisture_q u8); build_region_grid mirrors build_district_grid; protocol.gd region_grid passthrough (visual overlay deliberately out of scope); wire fixtures regenerated via make fixtures. atlas:: suite 507 green.

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

client/scripts/protocol/protocol.gd

@@ -774,11 +774,12 @@ static func decode_atlas_layer_response(bytes: PackedByteArray) -> Variant:
 ## road_graph/settlements (T-960): passthrough fields for the L2 road/rail
 ## graph and L3 settlement placements, mirroring the district_grid precedent
 ## (T-1046) — raw decoded maps/arrays, no further client-side reshaping.
-## Key names "road_graph"/"settlements" are the CONFIRMED wire contract —
+## region_grid (T-1113): the region climate grid, same passthrough pattern.
-## identical to server/src/atlas/layer_proxy.rs AtlasLayerResponse's field
+## Key names "road_graph"/"settlements"/"region_grid" are the CONFIRMED wire
-## names (pinned 2026-07-14; round-tripped by test_atlas_overlays.gd and the
+## contract — identical to server/src/atlas/layer_proxy.rs AtlasLayerResponse's
-## server's msgpack round-trip tests). This remains the one client-side spot
+## field names (pinned 2026-07-14; round-tripped by test_atlas_overlays.gd and
-## to touch if the contract ever changes.
+## the server's msgpack round-trip tests). This remains the one client-side
+## spot to touch if the contract ever changes.
 static func atlas_response_from_raw(raw: Variant) -> Variant:
 	if not raw is Dictionary or not raw.has("status"):
 		return null
@@ -798,6 +799,7 @@ static func atlas_response_from_raw(raw: Variant) -> Variant:
 		"district_grid": raw.get("district_grid"),
 		"road_graph": raw.get("road_graph"),
 		"settlements": raw.get("settlements"),
+		"region_grid": raw.get("region_grid"),
 	}
 
 

client/tests/fixtures/msgpack/atlas_response_not_found.msgpack

@@ -1 +1 @@
-†§body_id¥ghost¦status¨NotFound¦layer1À­district_gridÀªroad_graphÀ«settlementsÀ
+‡§body_id¥ghost¦status¨NotFound¦layer1À­district_gridÀªroad_graphÀ«settlementsÀ«region_gridÀ

client/tests/fixtures/msgpack/atlas_response_pending.msgpack

@@ -1 +1 @@
-�body_id二J1c存tatus判ending奸ayer1嶺district_grid尷road_graph屨settlements�
+𣇪body_id二J1c存tatus判ending奸ayer1嶺district_grid尷road_graph屨settlements屨region_grid�

server/src/atlas/body_world_state.rs

@@ -15,7 +15,9 @@ use serde::{Deserialize, Serialize};
 
 use crate::atlas::attractor_matching::CityPlacement;
 use crate::atlas::district_profile::{DistrictPos, DistrictProfile};
+use crate::atlas::region_profile::RegionProfile;
 use crate::atlas::road_graph::RoadGraph;
+use crate::atlas::scale::RegionPos;
 use crate::simulation::generator::{
     GeographicAttractor, QuarterId, QuarterWorldState, TerritorialStatus,
 };
@@ -100,6 +102,15 @@ pub struct BodyWorldState {
     /// `BTreeMap` keyed by `DistrictPos` for D-010 determinism.
     /// Empty until the DistrictProfile layer has run.
     pub districts: BTreeMap<DistrictPos, DistrictProfile>,
+    /// Per-region (~205 km) climate context — season/weather/temperature
+    /// baseline cells (D-243 §3, T-1113).
+    ///
+    /// Populated by the background cascade's Region layer; the covering grid
+    /// only (no blend-padding ring — see `cascade::LayerRegionOutput`).
+    /// `BTreeMap` keyed by `RegionPos` for D-010 determinism. Empty until the
+    /// Region layer has run. Footprint is trivial (~195×98 cells at the D-243
+    /// true-scale ceiling; a handful on today's working grids).
+    pub regions: BTreeMap<RegionPos, RegionProfile>,
     /// Last sim tick this entry was read. Used for LRU eviction.
     pub last_accessed: SimTick,
 }
@@ -224,6 +235,7 @@ mod tests {
             road_graph: RoadGraph::default(),
             quarters: BTreeMap::new(),
             districts: BTreeMap::new(),
+            regions: BTreeMap::new(),
             last_accessed: tick,
         }
     }

server/src/atlas/cascade.rs

@@ -28,8 +28,9 @@ use crate::atlas::district_profile::{self, BodyParams, DistrictPos, DistrictProf
 use crate::atlas::features::TerrainAnalysis;
 use crate::atlas::heightmap::{self, BodyHeightmap, HeightmapLoadError};
 use crate::atlas::layer1::{self, Layer1Output};
+use crate::atlas::region_profile::{self, RegionProfile};
 use crate::atlas::road_graph::{self, RoadGraph};
-use crate::atlas::scale;
+use crate::atlas::scale::{self, RegionPos};
 use crate::seed::SeedChain;
 use crate::simulation::generator::{CompatibilityMatrix, GeographicAttractor, TerritorialStatus};
 
@@ -57,6 +58,16 @@ pub enum CascadeLayer {
     /// last** to honour the append-only `Ord` rule (it neither needs nor blocks
     /// the DistrictProfile layer; requesting it runs DistrictProfile first, harmlessly).
     RoadGraph,
+    /// Region climate layer (~205 km cells, D-243 §3, T-1113). Pure function of
+    /// `(seed, body_params, heightmap dims)` — the region baselines the district
+    /// layer already derives internally (and discards) are RETAINED here as
+    /// their own layer output for the Atlas. Semantically the climate context
+    /// *above* districts, but **appended last** per the append-only `Ord` rule
+    /// (the RoadGraph precedent): it depends on no other layer, so requesting
+    /// it runs the earlier layers first, harmlessly. The cheap double-derive
+    /// (district blend cache + this layer) is deliberate — one layer, one
+    /// concern, no cache plumbing between layers.
+    Region,
 }
 
 /// Output of the cascade for one body, up to the requested layer (#952).
@@ -81,6 +92,9 @@ pub struct CascadeSnapshot {
     /// Layer 2 — inter-settlement road/rail graph. `Some` once
     /// [`CascadeLayer::RoadGraph`] has run (D-211, T-1038).
     pub road_graph: Option<RoadGraph>,
+    /// Region climate layer — ~205 km climate-context cells. `Some` once
+    /// [`CascadeLayer::Region`] has run (D-243 §3, T-1113).
+    pub layer_region: Option<LayerRegionOutput>,
     /// **Transient** — the `TerrainAnalysis` produced by the Layer-1 drainage
     /// pass (T-1044). Populated when Layer 1 runs; consumed (and freed) once
     /// both `DistrictProfile` and `RoadGraph` have consumed it.
@@ -98,6 +112,19 @@ pub struct LayerDistrictOutput {
     pub districts: std::collections::BTreeMap<DistrictPos, DistrictProfile>,
 }
 
+/// Region climate layer output (T-1113, D-243 §3): per-region (~205 km) climate
+/// context covering the body's district grid. Stored in `BodyWorldState.regions`.
+///
+/// The set is the **covering grid only** — the regions whose districts tile the
+/// body, with no ±1 neighbour padding. (The district layer's internal region
+/// cache pads a neighbour ring because its edge-fuzz blend samples across
+/// boundaries; that padding is a blend implementation detail, not part of the
+/// body's own region grid, and a dense Atlas wire encoding wants exact dims.)
+#[derive(Debug, Clone, Default)]
+pub struct LayerRegionOutput {
+    pub regions: std::collections::BTreeMap<RegionPos, RegionProfile>,
+}
+
 /// Layer 3 output (#955, D-211): attractor-matched settlement placements for the
 /// body. Re-derivable from (Layer-1 attractors + settlement records + seed).
 #[derive(Debug, Clone, Default)]
@@ -123,6 +150,7 @@ impl CascadeSnapshot {
             .layer_district
             .map(|lr| lr.districts)
             .unwrap_or_default();
+        let regions = self.layer_region.map(|lr| lr.regions).unwrap_or_default();
         let road_graph = self.road_graph.unwrap_or_default();
         // terrain_analysis (transient) is intentionally dropped here.
         let _ = self.terrain_analysis;
@@ -138,6 +166,7 @@ impl CascadeSnapshot {
             road_graph,
             quarters: std::collections::BTreeMap::new(),
             districts,
+            regions,
             last_accessed: 0,
         }
     }
@@ -203,6 +232,7 @@ pub fn run_cascade_from_heightmap(
         layer3: None,
         layer_district: None,
         road_graph: None,
+        layer_region: None,
         terrain_analysis: None,
     };
 
@@ -330,6 +360,42 @@ pub fn run_cascade_from_heightmap(
         snapshot.terrain_analysis = None;
     }
 
+    // Region climate layer (D-243 §3, T-1113) — the ~205 km climate-context
+    // cells the district blend already derives internally, retained as their
+    // own layer output. Pure function of (seed, body_params, heightmap dims):
+    // no TerrainAnalysis needed, so it runs outside the transient-borrow block
+    // above. Gates on body_params like the DistrictProfile layer (no params →
+    // no climate inputs → the layer skips, `regions` stays empty).
+    if up_to >= CascadeLayer::Region {
+        if let Some(params) = body_params {
+            // The covering region grid: the same district dims the district
+            // layer computes (heightmap dims ÷ cells-per-district), mapped up
+            // to region cells — WITHOUT the ±1 neighbour padding the district
+            // blend cache adds (see LayerRegionOutput's doc).
+            let gcpr = scale::HEIGHTMAP_CELLS_PER_DISTRICT.max(1);
+            let district_cols = (snapshot.heightmap.width as usize).div_ceil(gcpr) as i32;
+            let district_rows = (snapshot.heightmap.height as usize).div_ceil(gcpr) as i32;
+            let max_region = scale::district_to_region((
+                district_cols.saturating_sub(1),
+                district_rows.saturating_sub(1),
+            ));
+            let mut region_positions: Vec<RegionPos> = Vec::new();
+            for ry in 0..=max_region.1 {
+                for rx in 0..=max_region.0 {
+                    region_positions.push((rx, ry));
+                }
+            }
+            let climate = district_profile::ClimateConstants::default();
+            let regions = region_profile::derive_regions_for_body(
+                body_seed,
+                params,
+                &climate,
+                region_positions,
+            );
+            snapshot.layer_region = Some(LayerRegionOutput { regions });
+        }
+    }
+
     snapshot
 }
 
@@ -461,6 +527,7 @@ mod tests {
         assert!(CascadeLayer::Topography < CascadeLayer::Settlement);
         assert!(CascadeLayer::Settlement < CascadeLayer::DistrictProfile);
         assert!(CascadeLayer::DistrictProfile < CascadeLayer::RoadGraph);
+        assert!(CascadeLayer::RoadGraph < CascadeLayer::Region);
     }
 
     #[test]
@@ -794,4 +861,83 @@ mod tests {
         // Silence unused-import warning when the filter above changes.
         let _ = RoadNodeKind::Settlement;
     }
+
+    /// Region climate layer (T-1113, D-243 §3): runs as the cascade terminal,
+    /// populates `BodyWorldState.regions` with the covering region grid, gates
+    /// on body_params like the DistrictProfile layer, and is deterministic.
+    #[test]
+    fn region_layer_populates_regions_deterministically() {
+        use crate::atlas::district_profile::BodyParams;
+
+        let params = BodyParams {
+            hydrosphere: Some("ocean".into()),
+            atmosphere: Some("breathable".into()),
+            planet_class: Some("temperate".into()),
+            ..Default::default()
+        };
+        let run = || {
+            run_cascade_from_heightmap(
+                body_seed(),
+                test_heightmap(),
+                &[],
+                None,
+                Some(&params),
+                CascadeLayer::Region,
+            )
+        };
+        let snap = run();
+        let lr = snap.layer_region.as_ref().expect("Region layer ran");
+        // 64×32 working grid → 8×4 districts → a single covering region at
+        // (0,0) (100 districts per region side — the working grid is far
+        // inside one region cell today; the D-243 elastic seam grows this).
+        assert_eq!(lr.regions.len(), 1, "one covering region on the test grid");
+        let profile = lr.regions.get(&(0, 0)).expect("region (0,0) present");
+        assert!(
+            profile.clock.mean_temp_c.is_some(),
+            "breathable temperate body derives a temperature baseline"
+        );
+        assert!((0..=100).contains(&profile.moisture_q));
+
+        // Determinism: identical inputs → bit-identical region output.
+        let key = |s: &CascadeSnapshot| {
+            s.layer_region
+                .as_ref()
+                .unwrap()
+                .regions
+                .iter()
+                .map(|(pos, p)| {
+                    (
+                        *pos,
+                        p.clock.season as u8,
+                        p.clock.weather as u8,
+                        p.clock.mean_temp_c.map(f32::to_bits),
+                        p.moisture_q,
+                    )
+                })
+                .collect::<Vec<_>>()
+        };
+        assert_eq!(
+            key(&snap),
+            key(&run()),
+            "region layer must be deterministic"
+        );
+
+        // The regions propagate into the hot-cache BodyWorldState.
+        let state = snap.into_body_world_state();
+        assert_eq!(state.regions.len(), 1);
+        assert!(state.regions.contains_key(&(0, 0)));
+
+        // No body params → the layer skips and regions stays empty (mirrors
+        // the DistrictProfile gate).
+        let no_params = run_cascade_from_heightmap(
+            body_seed(),
+            test_heightmap(),
+            &[],
+            None,
+            None,
+            CascadeLayer::Region,
+        );
+        assert!(no_params.layer_region.is_none());
+        assert!(no_params.into_body_world_state().regions.is_empty());
+    }
 }

server/src/atlas/gen_queue.rs

@@ -407,13 +407,14 @@ fn run_work_item(item: &GenWorkItem) -> GenCompletion {
                 } else {
                     hm
                 };
-                // Run the full cascade through RoadGraph (Layer 2, T-1038), the
+                // Run the full cascade through Region (T-1113), the terminal
-                // terminal layer. It subsumes Settlement, DistrictProfile (T-1023),
+                // layer. It subsumes RoadGraph (T-1038), Settlement,
-                // and all prior layers. DistrictProfile derivation still gates on
+                // DistrictProfile (T-1023), and all prior layers.
-                // body_params internally (skipped when absent — e.g. a body with no
+                // DistrictProfile and Region derivation both gate on
-                // params row), but the road graph needs no body params, so it runs
+                // body_params internally (skipped when absent — e.g. a body
-                // for every analyzed body.
+                // with no params row), but the road graph needs no body
-                let up_to = CascadeLayer::RoadGraph;
+                // params, so it runs for every analyzed body.
+                let up_to = CascadeLayer::Region;
                 let snapshot = run_cascade_from_heightmap(
                     *body_seed,
                     working,

server/src/atlas/layer_proxy.rs

@@ -70,13 +70,13 @@ pub struct DistrictGridLayer {
 }
 
 /// A layer response: the computed `Layer1Output` + the coarse district grid
-/// (D-225, T-1046) + the road-graph and settlement overlays (T-960 §1/§2), or
+/// (D-225, T-1046) + the road-graph and settlement overlays (T-960 §1/§2) +
-/// a non-ready status.
+/// the region climate grid (T-1113), or a non-ready status.
 ///
 /// Growth ceiling (governance-bounded): the one-`Option`-field-per-layer
 /// pattern tops out around six fields — D-226's 2026-07-13 amendment (d)
 /// rules out any L5/tile Atlas layer ever, leaving T-1112 (quarter
-/// footprints) and T-1113 (region climate) as the only remaining candidates.
+/// footprints) as the only remaining candidate.
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct AtlasLayerResponse {
     pub body_id: String,
@@ -94,6 +94,9 @@ pub struct AtlasLayerResponse {
     /// The settlement-placement overlay (T-960 §2, #955). `Some` on a cache hit
     /// once the Settlement layer has placed at least one city; `None` otherwise.
     pub settlements: Option<SettlementLayer>,
+    /// The region climate grid for the Atlas overlay (D-243 §3, T-1113).
+    /// `Some` on a cache hit once the Region layer has run; `None` otherwise.
+    pub region_grid: Option<RegionGridLayer>,
 }
 
 /// Build the coarse [`DistrictGridLayer`] from a body's cached state (T-1046).
@@ -129,6 +132,83 @@ pub fn build_district_grid(
     })
 }
 
+// ---------------------------------------------------------------------------
+// RegionGridLayer (T-1113, D-243 §3)
+// ---------------------------------------------------------------------------
+
+/// The ~205 km region climate grid for the Atlas overlay (T-1113), dense
+/// row-major like [`DistrictGridLayer`] (the T-1046 encoding precedent).
+/// Serves the **mean-state** `RegionClock` fields only — the Q-105 tick-phase
+/// callbacks are deferred, so what ships is the static climate context.
+///
+/// Wire encoding is all-integer (D-010 wire discipline):
+/// - `season[i]` / `weather[i]` — the `repr(u8)` discriminants of
+///   `SeasonPhase` / `WeatherState` (pinned, append-only).
+/// - `mean_temp_dc[i]` — mean-annual temperature baseline in **deci-°C**
+///   (×10, `round`ed; 0.1 °C is ample for a map overlay). `i16::MIN` is the
+///   sentinel for "no atmosphere → no temperature" (airless bodies carry
+///   `mean_temp_c: None`); real values are class-band-clamped far inside
+///   i16 range.
+/// - `moisture_q[i]` — the 0–100 region moisture primitive.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct RegionGridLayer {
+    pub cols: u32,
+    pub rows: u32,
+    pub season: Vec<u8>,
+    pub weather: Vec<u8>,
+    pub mean_temp_dc: Vec<i16>,
+    pub moisture_q: Vec<u8>,
+}
+
+/// Sentinel for "airless body — no temperature baseline" in
+/// [`RegionGridLayer::mean_temp_dc`].
+pub const REGION_TEMP_NONE_DC: i16 = i16::MIN;
+
+/// Build the [`RegionGridLayer`] from a body's cached state (T-1113).
+/// Returns `None` when the Region layer has not run (empty `regions`).
+/// The stored region set is the dense covering grid `[0, cols) × [0, rows)`
+/// (see `cascade::LayerRegionOutput` — no blend-padding ring), so the extent
+/// comes from the maximum `RegionPos`, mirroring [`build_district_grid`].
+pub fn build_region_grid(
+    state: &crate::atlas::body_world_state::BodyWorldState,
+) -> Option<RegionGridLayer> {
+    if state.regions.is_empty() {
+        return None;
+    }
+    let cols = state.regions.keys().map(|(x, _)| *x).max().unwrap_or(0) as u32 + 1;
+    let rows = state.regions.keys().map(|(_, y)| *y).max().unwrap_or(0) as u32 + 1;
+    let n = (cols * rows) as usize;
+    let mut season = vec![0u8; n];
+    let mut weather = vec![0u8; n];
+    let mut mean_temp_dc = vec![REGION_TEMP_NONE_DC; n];
+    let mut moisture_q = vec![0u8; n];
+    for (&(x, y), profile) in &state.regions {
+        if x < 0 || y < 0 {
+            continue;
+        }
+        let i = (y as u32 * cols + x as u32) as usize;
+        if i < n {
+            season[i] = profile.clock.season as u8;
+            weather[i] = profile.clock.weather as u8;
+            mean_temp_dc[i] = match profile.clock.mean_temp_c {
+                Some(t) => {
+                    ((t * 10.0).round() as i32).clamp(i16::MIN as i32 + 1, i16::MAX as i32) as i16
+                }
+                None => REGION_TEMP_NONE_DC,
+            };
+            moisture_q[i] = profile.moisture_q.clamp(0, 100) as u8;
+        }
+    }
+    Some(RegionGridLayer {
+        cols,
+        rows,
+        season,
+        weather,
+        mean_temp_dc,
+        moisture_q,
+    })
+}
+
 // ---------------------------------------------------------------------------
 // RoadGraphLayer (T-960 §1, T-1038)
 // ---------------------------------------------------------------------------
@@ -341,6 +421,7 @@ pub fn handle_atlas_request(
         let district_grid = build_district_grid(state);
         let road_graph = build_road_graph_layer(state);
         let settlements = build_settlement_layer(state);
+        let region_grid = build_region_grid(state);
         return AtlasLayerResponse {
             body_id: req.body_id.clone(),
             status: AtlasLayerStatus::Ready,
@@ -348,6 +429,7 @@ pub fn handle_atlas_request(
             district_grid,
             road_graph,
             settlements,
+            region_grid,
         };
     }
 
@@ -420,6 +502,7 @@ pub fn handle_atlas_request(
                 district_grid: None,
                 road_graph: None,
                 settlements: None,
+                region_grid: None,
             }
         }
         // Unknown / no terrain → re-requesting won't help.
@@ -431,6 +514,7 @@ pub fn handle_atlas_request(
             district_grid: None,
             road_graph: None,
             settlements: None,
+            region_grid: None,
         },
         Err(e) => AtlasLayerResponse {
             body_id: req.body_id.clone(),
@@ -439,6 +523,7 @@ pub fn handle_atlas_request(
             district_grid: None,
             road_graph: None,
             settlements: None,
+            region_grid: None,
         },
     }
 }
@@ -487,6 +572,7 @@ mod tests {
             road_graph: crate::atlas::road_graph::RoadGraph::default(),
             quarters: std::collections::BTreeMap::new(),
             districts: std::collections::BTreeMap::new(),
+            regions: std::collections::BTreeMap::new(),
             last_accessed: 0,
         };
         // 3×2 grid with two distinct zones at the corners.
@@ -512,6 +598,64 @@ mod tests {
         assert!(build_district_grid(&state).is_none());
     }
 
+    /// T-1113: the region climate grid mirrors the district-grid encoding —
+    /// `None` when the Region layer hasn't run; dense row-major with the
+    /// integer wire quantization (deci-°C temp, `i16::MIN` airless sentinel)
+    /// when it has.
+    #[test]
+    fn build_region_grid_encodes_dense_quantized_climate() {
+        use crate::atlas::region_profile::{RegionClock, RegionProfile, SeasonPhase, WeatherState};
+
+        let mut state = blank_state("GJ1c");
+        // Empty regions → None (the Region layer hasn't run).
+        assert!(build_region_grid(&state).is_none());
+
+        // A 2×1 covering grid: one temperate region, one airless-style region
+        // (mean_temp_c = None → the sentinel).
+        state.regions.insert(
+            (0, 0),
+            RegionProfile {
+                pos: (0, 0),
+                clock: RegionClock {
+                    season: SeasonPhase::Summer,
+                    weather: WeatherState::Clear,
+                    mean_temp_c: Some(12.34),
+                },
+                latitude_deg: 45.0,
+                moisture_q: 80,
+            },
+        );
+        state.regions.insert(
+            (1, 0),
+            RegionProfile {
+                pos: (1, 0),
+                clock: RegionClock {
+                    season: SeasonPhase::Winter,
+                    weather: WeatherState::Snow,
+                    mean_temp_c: None,
+                },
+                latitude_deg: -10.0,
+                moisture_q: 5,
+            },
+        );
+
+        let grid = build_region_grid(&state).expect("regions present → Some grid");
+        assert_eq!((grid.cols, grid.rows), (2, 1));
+        assert_eq!(grid.season.len(), 2);
+        assert_eq!(grid.season[0], SeasonPhase::Summer as u8);
+        assert_eq!(grid.weather[0], WeatherState::Clear as u8);
+        // 12.34 °C → 123 deci-°C (rounded).
+        assert_eq!(grid.mean_temp_dc[0], 123);
+        assert_eq!(grid.moisture_q[0], 80);
+        assert_eq!(grid.season[1], SeasonPhase::Winter as u8);
+        assert_eq!(grid.weather[1], WeatherState::Snow as u8);
+        assert_eq!(
+            grid.mean_temp_dc[1], REGION_TEMP_NONE_DC,
+            "airless None maps to the sentinel"
+        );
+        assert_eq!(grid.moisture_q[1], 5);
+    }
+
     /// A blank `BodyWorldState` for tests that only care about one field —
     /// callers overwrite `placements`/`road_graph`/etc. as needed.
     fn blank_state(body_id: &str) -> BodyWorldState {
@@ -527,6 +671,7 @@ mod tests {
             road_graph: crate::atlas::road_graph::RoadGraph::default(),
             quarters: std::collections::BTreeMap::new(),
             districts: std::collections::BTreeMap::new(),
+            regions: std::collections::BTreeMap::new(),
             last_accessed: 0,
         }
     }
@@ -728,6 +873,7 @@ mod tests {
             district_grid: None,
             road_graph: build_road_graph_layer(&state),
             settlements: build_settlement_layer(&state),
+            region_grid: build_region_grid(&state),
         };
 
         let bytes = rmp_serde::to_vec_named(&resp).expect("encode");
@@ -829,6 +975,7 @@ mod tests {
             road_graph: crate::atlas::road_graph::RoadGraph::default(),
             quarters: std::collections::BTreeMap::new(),
             districts: std::collections::BTreeMap::new(),
+            regions: std::collections::BTreeMap::new(),
             last_accessed: 0,
         });
         let (_db, resolver) = empty_resolver();

server/src/atlas/plugin.rs

@@ -113,6 +113,7 @@ fn serve_atlas_requests(
                 district_grid: None,
                 road_graph: None,
                 settlements: None,
+                region_grid: None,
             },
         };
         responses.0.push(resp);

server/tests/gen_fixtures.rs

@@ -624,6 +624,7 @@ fn generate_atlas_layer_response_fixtures() {
         district_grid: None,
         road_graph: Some(road_graph),
         settlements: Some(settlements),
+        region_grid: None,
     };
     write_fixture(
         "atlas_response_ready",
@@ -637,6 +638,7 @@ fn generate_atlas_layer_response_fixtures() {
         district_grid: None,
         road_graph: None,
         settlements: None,
+        region_grid: None,
     };
     write_fixture(
         "atlas_response_pending",
@@ -650,6 +652,7 @@ fn generate_atlas_layer_response_fixtures() {
         district_grid: None,
         road_graph: None,
         settlements: None,
+        region_grid: None,
     };
     write_fixture(
         "atlas_response_not_found",