Lots of improvements

server-rs/src/data/travel_time.rs

@@ -8,8 +8,15 @@ use polars::lazy::frame::LazyFrame;
 use rustc_hash::{FxHashMap, FxHashSet};
 use tracing::info;
 
-/// Cached postcode → travel_minutes mapping for a single destination file.
-pub type TravelData = Arc<FxHashMap<String, i16>>;
+/// Per-postcode travel time data: median and optional best-case (transit only).
+#[derive(Clone, Copy)]
+pub struct TravelDataRow {
+    pub minutes: i16,
+    pub best_minutes: Option<i16>,
+}
+
+/// Cached postcode → travel time data for a single destination file.
+pub type TravelData = Arc<FxHashMap<String, TravelDataRow>>;
 
 /// Simple LRU cache for travel time data, limited to `capacity` entries.
 struct LruCache {
@@ -159,12 +166,23 @@ impl TravelTimeStore {
             .context("Missing 'travel_minutes' column")?
             .i16()
             .context("'travel_minutes' is not i16")?;
+        let best = df
+            .column("best_minutes")
+            .ok()
+            .map(|col| col.i16().expect("'best_minutes' is not i16"));
 
         let mut map = FxHashMap::default();
         map.reserve(df.height());
-        for (pc, min) in postcodes.into_iter().zip(minutes.into_iter()) {
+        for (i, (pc, min)) in postcodes.into_iter().zip(minutes.into_iter()).enumerate() {
             if let (Some(pc), Some(min)) = (pc, min) {
-                map.insert(pc.to_string(), min);
+                let best_min = best.as_ref().and_then(|b| b.get(i));
+                map.insert(
+                    pc.to_string(),
+                    TravelDataRow {
+                        minutes: min,
+                        best_minutes: best_min,
+                    },
+                );
             }
         }