diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 6d33a35..908f976 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -80,3 +80,49 @@ jobs:
 
       - name: Build
         run: npm run build
+
+  lint-rust:
+    name: Lint Rust
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: server-rs
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+        with:
+          components: clippy, rustfmt
+
+      - name: Cache cargo
+        uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: server-rs
+
+      - name: Run clippy
+        run: cargo clippy -- -D warnings
+
+      - name: Check formatting
+        run: cargo fmt --check
+
+  test-rust:
+    name: Test Rust
+    runs-on: ubuntu-latest
+    needs: [lint-rust]
+    defaults:
+      run:
+        working-directory: server-rs
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Install Rust toolchain
+        uses: dtolnay/rust-toolchain@stable
+
+      - name: Cache cargo
+        uses: Swatinem/rust-cache@v2
+        with:
+          workspaces: server-rs
+
+      - name: Run tests
+        run: cargo test
diff --git a/.vscode/settings.json b/.vscode/settings.json
index 3c9d529..702822d 100644
--- a/.vscode/settings.json
+++ b/.vscode/settings.json
@@ -3,8 +3,10 @@
         "*.venv": true,
         "**/__pycache__": true,
         "**/node_modules": true,
-        "**/.ruff_cache":true,
-        "**/.pytest_cache":true,
-        "**/target":true
+        "**/.ruff_cache": true,
+        "**/.pytest_cache": true,
+        "**/target": true,
+        "frontend/dist": true,
+        "**/.task": true
     }
-}
+}
\ No newline at end of file
diff --git a/Taskfile.yml b/Taskfile.yml
index 677d189..1e55c2d 100644
--- a/Taskfile.yml
+++ b/Taskfile.yml
@@ -42,7 +42,7 @@ tasks:
     dir: og-screenshot
     env:
       CACHE_DIR: /tmp/og-cache
-      NARROWIT_URL: http://localhost:3030
+      NARROWIT_URL: http://localhost:3000
     cmds:
       - npm install
       - npx playwright install --with-deps chromium
@@ -50,7 +50,7 @@ tasks:
       - npm start
 
   dev:frontend:
-    desc: Run frontend dev server on port 3030 (proxies /api to :8001)
+    desc: Run frontend dev server on port 3000 (proxies /api to :8001)
     dir: frontend
     deps:
       - install
diff --git a/frontend/src/lib/consts.ts b/frontend/src/lib/consts.ts
index 36b35af..6e5fd89 100644
--- a/frontend/src/lib/consts.ts
+++ b/frontend/src/lib/consts.ts
@@ -35,8 +35,9 @@ export const POSTCODE_ZOOM_THRESHOLD = 15;
 export const ZOOM_TO_RESOLUTION_THRESHOLDS = [
   { maxZoom: 7.5, resolution: 5 },
   { maxZoom: 9.5, resolution: 6 },
-  { maxZoom: 10.5, resolution: 8 },
-  { maxZoom: 12, resolution: 9 },
+  { maxZoom: 10.5, resolution: 7 },
+  { maxZoom: 11.5, resolution: 8 },
+  { maxZoom: 13, resolution: 9 },
   { maxZoom: Infinity, resolution: 10 },
 ] as const;
 
@@ -76,33 +77,66 @@ export const TWEMOJI_BASE = 'https://cdn.jsdelivr.net/gh/twitter/twemoji@14.0.2/
 export const OSM_ATTRIBUTION = '© <a href="https://openstreetmap.org">OpenStreetMap</a>';
 
 // =============================================================================
-// Crime Category Breakdowns
+// Stacked Chart Groups
 // =============================================================================
 
-/** Component crimes that make up each aggregate crime metric */
-export const CRIME_BREAKDOWNS: Record<string, string[]> = {
-  'Serious crime (avg/yr)': [
-    'Violence and sexual offences (avg/yr)',
-    'Robbery (avg/yr)',
-    'Burglary (avg/yr)',
-    'Possession of weapons (avg/yr)',
+export interface StackedChartConfig {
+  /** Display label for the chart */
+  label: string;
+  /** If set, use this feature's stats for the total and info popup. Otherwise sum components. */
+  feature?: string;
+  /** Suffix shown after the total value (e.g. "avg/yr") */
+  unit?: string;
+  /** Feature names that make up the segments */
+  components: string[];
+}
+
+/**
+ * Groups whose features should be collapsed into stacked bar charts.
+ * Keyed by feature group name. Each entry defines one stacked chart.
+ */
+export const STACKED_GROUPS: Record<string, StackedChartConfig[]> = {
+  Crime: [
+    {
+      label: 'Serious crime',
+      feature: 'Serious crime (avg/yr)',
+      unit: 'avg/yr',
+      components: [
+        'Violence and sexual offences (avg/yr)',
+        'Robbery (avg/yr)',
+        'Burglary (avg/yr)',
+        'Possession of weapons (avg/yr)',
+      ],
+    },
+    {
+      label: 'Minor crime',
+      feature: 'Minor crime (avg/yr)',
+      unit: 'avg/yr',
+      components: [
+        'Anti-social behaviour (avg/yr)',
+        'Criminal damage and arson (avg/yr)',
+        'Shoplifting (avg/yr)',
+        'Bicycle theft (avg/yr)',
+        'Theft from the person (avg/yr)',
+        'Other theft (avg/yr)',
+        'Vehicle crime (avg/yr)',
+        'Public order (avg/yr)',
+        'Drugs (avg/yr)',
+        'Other crime (avg/yr)',
+      ],
+    },
   ],
-  'Minor crime (avg/yr)': [
-    'Anti-social behaviour (avg/yr)',
-    'Criminal damage and arson (avg/yr)',
-    'Shoplifting (avg/yr)',
-    'Bicycle theft (avg/yr)',
-    'Theft from the person (avg/yr)',
-    'Other theft (avg/yr)',
-    'Vehicle crime (avg/yr)',
-    'Public order (avg/yr)',
-    'Drugs (avg/yr)',
-    'Other crime (avg/yr)',
+  Demographics: [
+    {
+      label: 'Ethnic composition',
+      unit: '%',
+      components: ['% White', '% Asian', '% Black', '% Mixed', '% Other'],
+    },
   ],
 };
 
-/** Colors for crime breakdown segments (designed for 10 distinct categories) */
-export const CRIME_SEGMENT_COLORS = [
+/** Colors for stacked bar segments */
+export const SEGMENT_COLORS = [
   '#ef4444', // red-500
   '#f97316', // orange-500
   '#eab308', // yellow-500