diff --git a/extract/padelnomics_extract/src/padelnomics_extract/eurostat.py b/extract/padelnomics_extract/src/padelnomics_extract/eurostat.py
index 6e45cd8..c7dcfe0 100644
--- a/extract/padelnomics_extract/src/padelnomics_extract/eurostat.py
+++ b/extract/padelnomics_extract/src/padelnomics_extract/eurostat.py
@@ -180,6 +180,8 @@ def extract(
     session: niquests.Session,
 ) -> dict:
     """Fetch all Eurostat datasets. Returns run metrics."""
+    assert landing_dir.is_dir(), f"landing_dir must exist: {landing_dir}"
+    assert "/" in year_month and len(year_month) == 7, f"year_month must be YYYY/MM: {year_month!r}"
     year, month = year_month.split("/")
     files_written = 0
     files_skipped = 0
diff --git a/extract/padelnomics_extract/src/padelnomics_extract/playtomic_availability.py b/extract/padelnomics_extract/src/padelnomics_extract/playtomic_availability.py
index 4c73b80..cb1e41c 100644
--- a/extract/padelnomics_extract/src/padelnomics_extract/playtomic_availability.py
+++ b/extract/padelnomics_extract/src/padelnomics_extract/playtomic_availability.py
@@ -59,6 +59,7 @@ _thread_local = threading.local()
 
 def _load_tenant_ids(landing_dir: Path) -> list[str]:
     """Read tenant IDs from the most recent tenants.json.gz file."""
+    assert landing_dir.is_dir(), f"landing_dir must exist: {landing_dir}"
     playtomic_dir = landing_dir / "playtomic"
     if not playtomic_dir.exists():
         return []
@@ -243,6 +244,8 @@ def extract(
     session: niquests.Session,
 ) -> dict:
     """Fetch next-day availability for all known Playtomic venues."""
+    assert landing_dir.is_dir(), f"landing_dir must exist: {landing_dir}"
+    assert "/" in year_month and len(year_month) == 7, f"year_month must be YYYY/MM: {year_month!r}"
     tenant_ids = _load_tenant_ids(landing_dir)
     if not tenant_ids:
         logger.warning("No tenant IDs found — run extract-playtomic-tenants first")
@@ -385,6 +388,8 @@ def extract_recheck(
     session: niquests.Session,
 ) -> dict:
     """Re-query venues with slots starting soon for accurate occupancy data."""
+    assert landing_dir.is_dir(), f"landing_dir must exist: {landing_dir}"
+    assert "/" in year_month and len(year_month) == 7, f"year_month must be YYYY/MM: {year_month!r}"
     now = datetime.now(UTC)
     target_date = now.strftime("%Y-%m-%d")