diff --git a/extract/padelnomics_extract/src/padelnomics_extract/playtomic_availability.py b/extract/padelnomics_extract/src/padelnomics_extract/playtomic_availability.py
index cb1e41c..6372191 100644
--- a/extract/padelnomics_extract/src/padelnomics_extract/playtomic_availability.py
+++ b/extract/padelnomics_extract/src/padelnomics_extract/playtomic_availability.py
@@ -42,7 +42,7 @@ MAX_VENUES_PER_RUN = 20_000
 MAX_RETRIES_PER_VENUE = 2
 MAX_WORKERS = int(os.environ.get("EXTRACT_WORKERS", "1"))
 RECHECK_WINDOW_MINUTES = int(os.environ.get("RECHECK_WINDOW_MINUTES", "90"))
-CIRCUIT_BREAKER_THRESHOLD = int(os.environ.get("CIRCUIT_BREAKER_THRESHOLD", "10"))
+CIRCUIT_BREAKER_THRESHOLD = int(os.environ.get("CIRCUIT_BREAKER_THRESHOLD") or "10")
 
 # Parallel mode submits futures in batches so the circuit breaker can stop
 # new submissions after it opens. Already-inflight futures in the current
diff --git a/src/padelnomics/export_serving.py b/src/padelnomics/export_serving.py
index 03d9384..9d79df6 100644
--- a/src/padelnomics/export_serving.py
+++ b/src/padelnomics/export_serving.py
@@ -26,6 +26,7 @@ Usage:
 
 import logging
 import os
+import re
 
 import duckdb
 
@@ -60,7 +61,6 @@ def export_serving() -> None:
         for view_name, view_sql in view_rows:
             # Pattern: ... FROM "local".sqlmesh__serving.serving__name__hash;
             # Strip the "local". prefix to get schema.table
-            import re
             match = re.search(r'FROM\s+"local"\.(sqlmesh__serving\.\S+)', view_sql)
             assert match, f"Cannot parse view definition for {view_name}: {view_sql[:200]}"
             physical_tables.append((view_name, match.group(1)))
diff --git a/web/src/padelnomics/sitemap.py b/web/src/padelnomics/sitemap.py
index 02e5010..6103093 100644
--- a/web/src/padelnomics/sitemap.py
+++ b/web/src/padelnomics/sitemap.py
@@ -6,6 +6,9 @@ from quart import Response
 
 from .core import fetch_all
 
+# Process-local cache — valid for the current single-Hypercorn-worker deployment
+# (Dockerfile: `--workers 1`). If worker count increases, replace with a
+# DB-backed cache (e.g. a single-row SQLite table with an expires_at column).
 _cache_xml: str = ""
 _cache_timestamp: float = 0.0
 CACHE_TTL_SECONDS: int = 3600  # 1 hour