England only

Makefile.data

@@ -46,11 +46,12 @@ PC_BOUNDARIES   := $(MANUAL_DATA)/postcode_boundaries
 TRANSIT_DIR     := $(DATA_DIR)/transit
 TRANSIT_STAMP   := $(TRANSIT_DIR)/.done
 GREENSPACE      := $(DATA_DIR)/greenspace_water.parquet
-PBF             := $(DATA_DIR)/great-britain-latest.osm.pbf
+PBF             := $(DATA_DIR)/england-latest.osm.pbf
 PLACES          := $(DATA_DIR)/places.parquet
 LISTINGS_BUY    := $(DATA_DIR)/online_listings_buy.parquet
 LISTINGS_RENT   := $(DATA_DIR)/online_listings_rent.parquet
 LSOA_POP        := $(DATA_DIR)/lsoa_population.parquet
+ENGLAND_BOUNDARY := $(DATA_DIR)/england_boundary.geojson
 RM_OUTCODES     := frontend/src/lib/rightmove-outcodes.json
 
 # Sentinel files for directory targets (Make doesn't track directories well)
@@ -65,7 +66,7 @@ PMTILES_VERSION := 1.22.3
         download-arcgis download-price-paid download-deprivation download-ethnicity \
         download-naptan download-pois download-ofsted download-broadband download-rental-prices \
         download-postcodes download-geosure download-noise download-inspire \
-        download-oa-boundaries download-uprn-lookup download-transit-network download-greenspace download-pbf download-places download-lsoa-population download-rightmove-outcodes \
+        download-oa-boundaries download-uprn-lookup download-transit-network download-greenspace download-pbf download-places download-lsoa-population download-england-boundary download-rightmove-outcodes \
         transform-pois transform-epc-pp transform-crime transform-poi-proximity \
         transform-school-proximity transform-geosure transform-postcode-boundaries \
         generate-postcode-boundaries
@@ -93,6 +94,7 @@ download-greenspace:          $(GREENSPACE)
 download-pbf:                 $(PBF)
 download-places:              $(PLACES)
 download-lsoa-population:       $(LSOA_POP)
+download-england-boundary:    $(ENGLAND_BOUNDARY)
 download-rightmove-outcodes:    $(RM_OUTCODES)
 transform-pois:               $(POIS_FILTERED)
 transform-epc-pp:             $(EPC_PP)
@@ -141,11 +143,11 @@ $(NAPTAN):
 
 $(PBF):
 	@mkdir -p $(DATA_DIR)
-	curl -L -o $@.tmp https://download.geofabrik.de/europe/great-britain-latest.osm.pbf
+	curl -L -o $@.tmp https://download.geofabrik.de/europe/united-kingdom/england-latest.osm.pbf
 	mv $@.tmp $@
 
-$(POIS_RAW): $(PBF)
+$(POIS_RAW): $(PBF) $(ENGLAND_BOUNDARY)
-	uv run python -m pipeline.download.pois --output $@ --pbf $(PBF)
+	uv run python -m pipeline.download.pois --output $@ --pbf $(PBF) --boundary $(ENGLAND_BOUNDARY)
 
 $(OFSTED):
 	uv run python -m pipeline.download.ofsted --output $@
@@ -183,19 +185,22 @@ $(RENTAL):
 $(GREENSPACE): $(PBF)
 	uv run python -m pipeline.download.greenspace_water --output $@ --pbf $(PBF)
 
-$(PLACES): $(PBF)
+$(PLACES): $(PBF) $(ENGLAND_BOUNDARY)
-	uv run python -m pipeline.download.places --output $@ --pbf $(PBF)
+	uv run python -m pipeline.download.places --output $@ --pbf $(PBF) --boundary $(ENGLAND_BOUNDARY)
 
 $(LSOA_POP):
 	uv run python -m pipeline.download.lsoa_population --output $@
 
+$(ENGLAND_BOUNDARY):
+	uv run python -m pipeline.download.england_boundary --output $@
+
 $(RM_OUTCODES): $(MERGE_STAMP)
 	uv run python -m pipeline.download.rightmove_outcodes --postcodes $(POSTCODES_PQ) --output $@
 
 # ── Transforms ────────────────────────────────────────────────────────────────
 
-$(POIS_FILTERED): $(POIS_RAW) $(NAPTAN)
+$(POIS_FILTERED): $(POIS_RAW) $(NAPTAN) $(ENGLAND_BOUNDARY)
-	uv run python -m pipeline.transform.transform_poi --input $(POIS_RAW) --naptan $(NAPTAN) --output $@
+	uv run python -m pipeline.transform.transform_poi --input $(POIS_RAW) --naptan $(NAPTAN) --boundary $(ENGLAND_BOUNDARY) --output $@
 
 $(EPC_PP): $(PRICE_PAID) $(EPC)
 	uv run python -m pipeline.transform.join_epc_pp --epc $(EPC) --price-paid $(PRICE_PAID) --output $@

frontend/src/components/map/AiFilterInput.tsx

@@ -1,8 +1,42 @@
-import { memo, useState, useCallback } from 'react';
+import { memo, useState, useCallback, useEffect, useRef } from 'react';
 import { SpinnerIcon } from '../ui/icons/SpinnerIcon';
 import { SparklesIcon } from '../ui/icons/SparklesIcon';
 import type { AiFilterErrorType } from '../../hooks/useAiFilters';
 
+const EXAMPLE_QUERIES = [
+  'Safe area near good schools',
+  '30 min commute to Kings Cross, under 500k',
+  'Quiet village, 3 bed, fast broadband',
+];
+
+const LOADING_MESSAGES = [
+  'Analysing your query...',
+  'Searching for destinations...',
+  'Generating filters...',
+];
+
+/** Cycle through loading messages to show progress. */
+function useLoadingMessage(loading: boolean): string {
+  const [index, setIndex] = useState(0);
+  const timerRef = useRef<ReturnType<typeof setTimeout>>();
+
+  useEffect(() => {
+    if (!loading) {
+      setIndex(0);
+      return;
+    }
+    // Advance message every 1.5s
+    timerRef.current = setTimeout(() => setIndex(1), 1500);
+    const t2 = setTimeout(() => setIndex(2), 3500);
+    return () => {
+      clearTimeout(timerRef.current);
+      clearTimeout(t2);
+    };
+  }, [loading]);
+
+  return LOADING_MESSAGES[index];
+}
+
 interface AiFilterInputProps {
   loading: boolean;
   error: string | null;
@@ -23,6 +57,8 @@ export default memo(function AiFilterInput({
   onLoginRequired,
 }: AiFilterInputProps) {
   const [query, setQuery] = useState('');
+  const [expanded, setExpanded] = useState(false);
+  const loadingMessage = useLoadingMessage(loading);
 
   const handleSubmit = useCallback(
     (e: React.FormEvent) => {
@@ -38,36 +74,90 @@ export default memo(function AiFilterInput({
     [query, loading, isLoggedIn, onLoginRequired, onSubmit]
   );
 
+  const handleExampleClick = useCallback(
+    (example: string) => {
+      if (loading) return;
+      setQuery(example);
+      if (!isLoggedIn) {
+        onLoginRequired();
+        return;
+      }
+      onSubmit(example);
+    },
+    [loading, isLoggedIn, onLoginRequired, onSubmit]
+  );
+
   const hasContent = query.trim().length > 0;
+  const showExamples = expanded && !hasContent && !loading && !error && !notes;
+
+  if (!expanded) {
+    return (
+      <div className="px-3 py-2" data-tutorial="ai-filters">
+        <button
+          type="button"
+          onClick={() => setExpanded(true)}
+          className="w-full flex items-center gap-2 px-3 py-2 rounded-lg border border-dashed border-teal-300 dark:border-teal-700 bg-teal-50/50 dark:bg-teal-900/20 hover:bg-teal-50 dark:hover:bg-teal-900/30 cursor-pointer group"
+        >
+          <SparklesIcon className="w-4 h-4 text-teal-500 dark:text-teal-400 shrink-0" />
+          <span className="text-sm text-teal-700 dark:text-teal-300 group-hover:text-teal-800 dark:group-hover:text-teal-200">
+            Describe your ideal area with AI
+          </span>
+        </button>
+      </div>
+    );
+  }
 
   return (
     <div className="px-3 py-2" data-tutorial="ai-filters">
+      <div className="flex items-center gap-1.5 mb-1.5">
+        <SparklesIcon className="w-3.5 h-3.5 text-teal-500 dark:text-teal-400 shrink-0" />
+        <span className="text-xs font-medium text-teal-700 dark:text-teal-300">AI Search</span>
+        <span className="text-xs text-warm-400 dark:text-warm-500">— describe what you're looking for</span>
+      </div>
       <form onSubmit={handleSubmit} className="flex items-center gap-1.5">
-        <div className="relative flex-1">
+        <input
-          <SparklesIcon className="absolute left-2 top-1/2 -translate-y-1/2 w-3.5 h-3.5 text-teal-500 dark:text-teal-400 pointer-events-none" />
+          type="text"
-          <input
+          value={query}
-            type="text"
+          onChange={(e) => setQuery(e.target.value)}
-            value={query}
+          placeholder="e.g. quiet area, under 400k, near good schools..."
-            onChange={(e) => setQuery(e.target.value)}
+          className="flex-1 px-2.5 py-1.5 text-sm rounded-lg border border-warm-200 dark:border-warm-700 bg-warm-50 dark:bg-warm-800 text-warm-700 dark:text-warm-200 placeholder-warm-400 dark:placeholder-warm-500 focus:outline-none focus:ring-2 focus:ring-teal-400 focus:bg-white dark:focus:bg-warm-800"
-            placeholder="Describe your ideal area..."
+          disabled={loading}
-            className="w-full pl-7 pr-2.5 py-1.5 text-sm rounded-lg border border-warm-200 dark:border-warm-700 bg-warm-50 dark:bg-warm-800 text-warm-700 dark:text-warm-200 placeholder-warm-400 dark:placeholder-warm-500 focus:outline-none focus:ring-2 focus:ring-teal-400 focus:bg-white dark:focus:bg-warm-800"
+          autoFocus
-            disabled={loading}
+        />
-          />
+        <button
-        </div>
+          type="submit"
-        {(hasContent || loading) && (
+          disabled={loading || !hasContent}
-          <button
+          className="shrink-0 px-3 py-1.5 rounded-lg bg-teal-600 hover:bg-teal-700 disabled:opacity-50 disabled:cursor-not-allowed text-white text-sm font-medium flex items-center gap-1.5"
-            type="submit"
+        >
-            disabled={loading || !hasContent}
+          {loading ? (
-            className="shrink-0 px-2.5 py-1.5 rounded-lg bg-teal-600 hover:bg-teal-700 disabled:opacity-50 disabled:cursor-not-allowed text-white text-sm font-medium flex items-center justify-center"
+            <SpinnerIcon className="w-3.5 h-3.5 animate-spin" />
-          >
+          ) : (
-            {loading ? (
+            <>
-              <SpinnerIcon className="w-4 h-4 animate-spin" />
+              <SparklesIcon className="w-3.5 h-3.5" />
-            ) : (
+              <span>Search</span>
-              <SparklesIcon className="w-4 h-4" />
+            </>
-            )}
+          )}
-          </button>
+        </button>
-        )}
       </form>
+      {loading && (
+        <p className="mt-1 text-xs text-teal-600 dark:text-teal-400">
+          {loadingMessage}
+        </p>
+      )}
+      {showExamples && (
+        <div className="mt-1.5 flex flex-wrap gap-1">
+          {EXAMPLE_QUERIES.map((example) => (
+            <button
+              key={example}
+              type="button"
+              onClick={() => handleExampleClick(example)}
+              className="text-xs px-2 py-0.5 rounded-full border border-warm-200 dark:border-warm-700 text-warm-500 dark:text-warm-400 hover:border-teal-400 hover:text-teal-600 dark:hover:text-teal-400 cursor-pointer"
+            >
+              {example}
+            </button>
+          ))}
+        </div>
+      )}
       {error && errorType === 'verification' && (
         <p className="mt-1.5 text-xs text-amber-600 dark:text-amber-400">
           Please verify your email address to use AI-powered search. Check your inbox for a verification link.
@@ -83,7 +173,7 @@ export default memo(function AiFilterInput({
           {error}
         </p>
       )}
-      {notes && !error && (
+      {notes && !error && !loading && (
         <p className="mt-1 text-xs text-warm-500 dark:text-warm-400 italic">
           {notes}
         </p>

pipeline/download/england_boundary.py

@@ -0,0 +1,45 @@
+"""Download England country boundary GeoJSON from ONS Open Geography Portal.
+
+Source: ONS Countries (December 2024) Boundaries UK BGC (Generalised Clipped)
+Licence: OGL v3
+"""
+
+import argparse
+from pathlib import Path
+
+import httpx
+
+# ArcGIS REST API — query for England only, generalised (BGC) resolution
+URL = (
+    "https://services1.arcgis.com/ESMARspQHYMw9BZ9/arcgis/rest/services/"
+    "Countries_December_2024_Boundaries_UK_BGC/FeatureServer/0/query"
+    "?where=CTRY24NM%3D%27England%27&outFields=CTRY24NM&f=geojson"
+)
+
+
+def main() -> None:
+    parser = argparse.ArgumentParser(
+        description="Download England country boundary GeoJSON"
+    )
+    parser.add_argument(
+        "--output", type=Path, required=True, help="Output GeoJSON file path"
+    )
+    args = parser.parse_args()
+    args.output.parent.mkdir(parents=True, exist_ok=True)
+
+    print("Downloading England boundary from ONS...")
+    response = httpx.get(URL, follow_redirects=True, timeout=60)
+    response.raise_for_status()
+
+    data = response.json()
+    features = data.get("features", [])
+    if len(features) != 1:
+        raise ValueError(f"Expected 1 feature for England, got {len(features)}")
+
+    args.output.write_text(response.text)
+    size_kb = args.output.stat().st_size / 1024
+    print(f"Saved to {args.output} ({size_kb:.0f} KB)")
+
+
+if __name__ == "__main__":
+    main()

pipeline/download/map_assets.py

@@ -7,6 +7,7 @@ from pathlib import Path
 from pipeline.transform.transform_poi import NAPTAN_EMOJIS, _CATEGORIES
 
 GLYPHS_BASE = "https://protomaps.github.io/basemaps-assets/fonts"
+SPRITES_BASE = "https://protomaps.github.io/basemaps-assets/sprites/v4"
 TWEMOJI_BASE = "https://cdn.jsdelivr.net/gh/twitter/twemoji@14.0.2/assets/72x72"
 
 # Font stacks used by @protomaps/basemaps with lang='en'
@@ -77,6 +78,15 @@ def main():
             url = f"{GLYPHS_BASE}/{font_encoded}/{name}"
             tasks.append((url, font_dir / name))
 
+    # Sprite sheets (light/dark, 1x and 2x)
+    sprites_dir = out / "sprites"
+    for theme in ("light", "dark"):
+        for suffix in ("json", "png"):
+            url = f"{SPRITES_BASE}/{theme}.{suffix}"
+            tasks.append((url, sprites_dir / f"{theme}.{suffix}"))
+            url_2x = f"{SPRITES_BASE}/{theme}@2x.{suffix}"
+            tasks.append((url_2x, sprites_dir / f"{theme}@2x.{suffix}"))
+
     # Twemoji PNGs
     twemoji_dir = out / "twemoji"
     for code in twemoji_codes:

pipeline/download/places.py

@@ -2,7 +2,7 @@
 
 Extracts named place nodes (cities, towns, suburbs, etc.) and railway stations
 (tube, national rail, DLR, etc.) for typeahead search.
-Reuses the same great-britain-latest.osm.pbf as pois.py.
+Reuses the same england-latest.osm.pbf as pois.py.
 """
 
 import argparse
@@ -10,9 +10,16 @@ from pathlib import Path
 
 import osmium
 import polars as pl
+from shapely.geometry import Point
 from tqdm import tqdm
 
-from .pois import UK_BBOX_EAST, UK_BBOX_NORTH, UK_BBOX_SOUTH, UK_BBOX_WEST
+from pipeline.download.pois import (
+    ENGLAND_BBOX_EAST,
+    ENGLAND_BBOX_NORTH,
+    ENGLAND_BBOX_SOUTH,
+    ENGLAND_BBOX_WEST,
+)
+from pipeline.utils.england_geometry import load_england_polygon
 
 PLACE_TYPES = {"city"}
 
@@ -57,10 +64,11 @@ def _station_display_name(name: str, tags: dict[str, str]) -> str:
 
 
 class PlaceHandler(osmium.SimpleHandler):
-    def __init__(self, progress: tqdm) -> None:
+    def __init__(self, progress: tqdm, england_polygon) -> None:
         super().__init__()
         self._progress = progress
         self.places: list[dict] = []
+        self._england = england_polygon
 
     def _add(
         self, name: str, place_type: str, lat: float, lon: float, population: int
@@ -82,10 +90,12 @@ class PlaceHandler(osmium.SimpleHandler):
             return
         lat, lon = n.location.lat, n.location.lon
         if not (
-            UK_BBOX_SOUTH <= lat <= UK_BBOX_NORTH
+            ENGLAND_BBOX_SOUTH <= lat <= ENGLAND_BBOX_NORTH
-            and UK_BBOX_WEST <= lon <= UK_BBOX_EAST
+            and ENGLAND_BBOX_WEST <= lon <= ENGLAND_BBOX_EAST
         ):
             return
+        if not self._england.contains(Point(lon, lat)):
+            return
 
         name = n.tags.get("name:en", n.tags.get("name", ""))
         if not name:
@@ -124,9 +134,17 @@ def main() -> None:
     parser.add_argument(
         "--pbf", type=Path, required=True, help="Path to OSM PBF file"
     )
+    parser.add_argument(
+        "--boundary",
+        type=Path,
+        required=True,
+        help="England boundary GeoJSON file",
+    )
     args = parser.parse_args()
 
     pbf_file = args.pbf
+    england_polygon = load_england_polygon(args.boundary)
+
     print("Extracting place nodes: cities + railway stations")
     with tqdm(
         unit=" elements",
@@ -135,7 +153,7 @@ def main() -> None:
         smoothing=0.05,
         mininterval=1.0,
     ) as progress:
-        handler = PlaceHandler(progress)
+        handler = PlaceHandler(progress, england_polygon)
         handler.apply_file(str(pbf_file), locations=True)
 
     print(f"Extracted {len(handler.places):,} place nodes")

pipeline/download/pois.py

@@ -4,17 +4,20 @@ from tempfile import mkdtemp
 
 import osmium
 import polars as pl
+from shapely.geometry import Point
 from tqdm import tqdm
 
+from pipeline.utils.england_geometry import load_england_polygon
 
 BATCH_SIZE = 50_000
 
 MIN_OCCURENCE_COUNT = 20
 
-UK_BBOX_WEST = -7.57
+# Bounding box for fast pre-filtering before the precise polygon check
-UK_BBOX_SOUTH = 49.96
+ENGLAND_BBOX_WEST = -6.45
-UK_BBOX_EAST = 1.68
+ENGLAND_BBOX_SOUTH = 49.85
-UK_BBOX_NORTH = 58.64
+ENGLAND_BBOX_EAST = 1.77
+ENGLAND_BBOX_NORTH = 55.82
 
 POI_TAG_KEYS: list[str] = [
     "amenity",
@@ -31,19 +34,23 @@ POI_TAG_KEYS: list[str] = [
 
 
 class POIHandler(osmium.SimpleHandler):
-    def __init__(self, progress: tqdm, tmp_dir: Path) -> None:
+    def __init__(self, progress: tqdm, tmp_dir: Path, england_polygon) -> None:
         super().__init__()
         self._batch: list[dict] = []
         self._tmp_dir = tmp_dir
         self._batch_num = 0
         self.poi_count = 0
         self._progress = progress
+        self._england = england_polygon
 
-    def _in_uk(self, lat: float, lon: float) -> bool:
+    def _in_england(self, lat: float, lon: float) -> bool:
-        return (
+        # Fast bbox pre-filter, then precise polygon check
-            UK_BBOX_SOUTH <= lat <= UK_BBOX_NORTH
+        if not (
-            and UK_BBOX_WEST <= lon <= UK_BBOX_EAST
+            ENGLAND_BBOX_SOUTH <= lat <= ENGLAND_BBOX_NORTH
-        )
+            and ENGLAND_BBOX_WEST <= lon <= ENGLAND_BBOX_EAST
+        ):
+            return False
+        return self._england.contains(Point(lon, lat))
 
     def _match_tags(self, tags: osmium.osm.TagList) -> list[str]:
         return [f"{key}/{tags[key]}" for key in POI_TAG_KEYS if key in tags]
@@ -90,7 +97,7 @@ class POIHandler(osmium.SimpleHandler):
         if not n.location.valid:
             return
         lat, lon = n.location.lat, n.location.lon
-        if not self._in_uk(lat, lon):
+        if not self._in_england(lat, lon):
             return
         categories = self._match_tags(n.tags)
         for category in categories:
@@ -107,11 +114,19 @@ def main() -> None:
     parser.add_argument(
         "--pbf", type=Path, required=True, help="Path to OSM PBF file"
     )
+    parser.add_argument(
+        "--boundary",
+        type=Path,
+        required=True,
+        help="England boundary GeoJSON file",
+    )
     args = parser.parse_args()
 
     pbf_file = args.pbf
     print(f"Tag keys: {POI_TAG_KEYS}")
 
+    england_polygon = load_england_polygon(args.boundary)
+
     tmp_dir = Path(mkdtemp(prefix="pois_"))
     with tqdm(
         unit=" elements",
@@ -120,7 +135,7 @@ def main() -> None:
         smoothing=0.05,
         mininterval=1.0,
     ) as progress:
-        handler = POIHandler(progress, tmp_dir)
+        handler = POIHandler(progress, tmp_dir, england_polygon)
         handler.apply_file(str(pbf_file), locations=True)
         handler._flush_batch()  # write any remaining POIs
 

pipeline/transform/transform_poi.py

@@ -3,6 +3,8 @@ from pathlib import Path
 
 import polars as pl
 
+from pipeline.utils.england_geometry import in_england_mask
+
 
 DROP_CATEGORIES = {
     # Street furniture & infrastructure
@@ -1056,7 +1058,11 @@ NAPTAN_EMOJIS: dict[str, str] = {
 }
 
 
-def transform(input_path: Path, naptan_path: Path | None = None) -> pl.LazyFrame:
+def transform(
+    input_path: Path,
+    naptan_path: Path | None = None,
+    boundary_path: Path | None = None,
+) -> pl.LazyFrame:
     lf = pl.scan_parquet(input_path)
 
     # Get all unique categories present in the data
@@ -1072,16 +1078,14 @@ def transform(input_path: Path, naptan_path: Path | None = None) -> pl.LazyFrame
     if unmapped:
         raise ValueError(f"Categories missing from CATEGORY_MAP: {sorted(unmapped)}")
 
-    # Verify every CATEGORY_MAP key actually exists in the data (catch typos)
+    # Warn about CATEGORY_MAP keys not in data (may be absent in regional extracts)
     mapped_but_absent = []
     all_set = set(all_categories)
     for cat in CATEGORY_MAP:
         if cat not in all_set:
             mapped_but_absent.append(cat)
     if mapped_but_absent:
-        raise ValueError(
+        print(f"CATEGORY_MAP categories not in data (skipped): {sorted(mapped_but_absent)}")
-            f"CATEGORY_MAP contains categories not in data: {sorted(mapped_but_absent)}"
-        )
 
     # Drop unwanted categories
     lf = lf.filter(~pl.col("category").is_in(list(DROP_CATEGORIES)))
@@ -1105,7 +1109,15 @@ def transform(input_path: Path, naptan_path: Path | None = None) -> pl.LazyFrame
         pl.col("category").replace_strict(emoji_mapping).alias("emoji"),
     )
 
-    naptan = pl.scan_parquet(naptan_path).with_columns(
+    naptan_df = pl.scan_parquet(naptan_path).collect()
+    if boundary_path is not None:
+        mask = in_england_mask(
+            boundary_path,
+            naptan_df["lat"].to_numpy(),
+            naptan_df["lng"].to_numpy(),
+        )
+        naptan_df = naptan_df.filter(pl.Series(mask))
+    naptan = naptan_df.lazy().with_columns(
         pl.col("category").replace_strict(NAPTAN_EMOJIS).alias("emoji"),
         pl.lit("Public Transport").alias("group"),
     )
@@ -1122,12 +1134,18 @@ def main():
     parser.add_argument(
         "--naptan", type=Path, required=True, help="NaPTAN stations parquet file"
     )
+    parser.add_argument(
+        "--boundary",
+        type=Path,
+        required=True,
+        help="England boundary GeoJSON file",
+    )
     parser.add_argument(
         "--output", type=Path, required=True, help="Output filtered POIs parquet file"
     )
     args = parser.parse_args()
 
-    df = transform(args.input, args.naptan).collect(engine="streaming")
+    df = transform(args.input, args.naptan, args.boundary).collect(engine="streaming")
 
     df.write_parquet(args.output)
 

pipeline/utils/england_geometry.py

@@ -0,0 +1,33 @@
+"""England boundary polygon for accurate point-in-country filtering.
+
+Uses shapely prepared geometry for fast single-point checks (osmium handlers)
+and vectorized shapely.contains for batch checks (Polars DataFrames).
+"""
+
+import json
+from pathlib import Path
+
+import numpy as np
+import shapely
+from shapely.geometry import shape
+from shapely.prepared import PreparedGeometry, prep
+
+
+def load_england_polygon(geojson_path: Path) -> PreparedGeometry:
+    """Load England boundary as a prepared shapely polygon for fast contains checks."""
+    with open(geojson_path) as f:
+        data = json.load(f)
+    geometry = shape(data["features"][0]["geometry"])
+    return prep(geometry)
+
+
+def in_england_mask(geojson_path: Path, lats: np.ndarray, lngs: np.ndarray) -> np.ndarray:
+    """Vectorized check: which (lat, lng) points are within England.
+
+    Returns a boolean numpy array.
+    """
+    with open(geojson_path) as f:
+        data = json.load(f)
+    polygon = shape(data["features"][0]["geometry"])
+    pts = shapely.points(lngs, lats)
+    return shapely.contains(polygon, pts)