Fix POI distance calculation: OSRM index separator and error handling

- Fix OSRM client to use semicolons (not commas) for source/destination
  indices in /table API requests. Commas caused "Query string malformed"
  errors for any batch with more than one origin.
- Add error handling in poi_distance_calculator for unreachable routing
  engines (OSRM/OTP). Connection failures now log an error and skip the
  mode instead of crashing the entire Celery task.

rec/osrm_client.py

@@ -47,8 +47,8 @@ async def osrm_table(
     coords_str = ";".join(f"{lng},{lat}" for lng, lat in all_coords)
 
     # Source/destination indices
-    source_indices = ",".join(str(i) for i in range(len(origins)))
+    source_indices = ";".join(str(i) for i in range(len(origins)))
-    dest_indices = ",".join(str(i) for i in range(len(origins), len(all_coords)))
+    dest_indices = ";".join(str(i) for i in range(len(origins), len(all_coords)))
 
     url = (
         f"{base_url}/table/v1/{profile}/{coords_str}"

services/poi_distance_calculator.py

@@ -88,20 +88,29 @@ async def calculate_poi_distances(
             f"(skipped {len(existing)} already computed)"
         )
 
-        if mode_upper in _OSRM_PROFILES:
+        try:
-            computed = await _compute_osrm(
+            if mode_upper in _OSRM_PROFILES:
-                pending_listings, poi, mode_upper, listing_type,
+                computed = await _compute_osrm(
-                config, poi_repo, on_progress,
+                    pending_listings, poi, mode_upper, listing_type,
-                total_computed, len(listings) * total_modes,
+                    config, poi_repo, on_progress,
-            )
+                    total_computed, len(listings) * total_modes,
-        elif mode_upper == "TRANSIT":
+                )
-            computed = await _compute_transit(
+            elif mode_upper == "TRANSIT":
-                pending_listings, poi, listing_type,
+                computed = await _compute_transit(
-                config, poi_repo, on_progress,
+                    pending_listings, poi, listing_type,
-                total_computed, len(listings) * total_modes,
+                    config, poi_repo, on_progress,
-            )
+                    total_computed, len(listings) * total_modes,
-        else:
+                )
-            logger.warning(f"Unknown travel mode: {mode_upper}")
+            else:
+                logger.warning(f"Unknown travel mode: {mode_upper}")
+                continue
+        except (aiohttp.ClientError, OSError) as e:
+            logger.error(f"Routing engine unreachable for {mode_upper}: {e}")
+            if on_progress:
+                on_progress(
+                    total_computed, len(listings) * total_modes,
+                    f"{mode_upper}: routing engine unavailable"
+                )
             continue
 
         total_computed += computed