Always fresh-download calibration inputs, clear stale builds

The Modal volume was caching old calibration inputs from previous runs.
The code only checked file existence, not freshness, so new model fits
on HuggingFace were never pulled. Also clear the version build directory
to prevent stale h5 files (built from old weights) from being treated
as completed by the volume checkpoint system.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: baogorek

modal_app/local_area.py

@@ -430,11 +430,18 @@ def coordinate_publish(
     print(f"Publishing version {version} from branch {branch}")
     print(f"Using {num_workers} parallel workers")
 
+    import shutil
+
     staging_dir = Path(VOLUME_MOUNT)
     version_dir = staging_dir / version
+    if version_dir.exists():
+        print(f"Clearing stale build directory: {version_dir}")
+        shutil.rmtree(version_dir)
     version_dir.mkdir(parents=True, exist_ok=True)
 
     calibration_dir = staging_dir / "calibration_inputs"
+    if calibration_dir.exists():
+        shutil.rmtree(calibration_dir)
     calibration_dir.mkdir(parents=True, exist_ok=True)
 
     # hf_hub_download preserves directory structure, so files are in calibration/ subdir
@@ -446,29 +453,26 @@ def coordinate_publish(
     )
     db_path = calibration_dir / "calibration" / "policy_data.db"
 
-    if not all(p.exists() for p in [weights_path, dataset_path, db_path]):
-        print("Downloading calibration inputs...")
-        result = subprocess.run(
-            [
-                "uv",
-                "run",
-                "python",
-                "-c",
-                f"""
+    print("Downloading calibration inputs from HuggingFace...")
+    result = subprocess.run(
+        [
+            "uv",
+            "run",
+            "python",
+            "-c",
+            f"""
 from policyengine_us_data.utils.huggingface import download_calibration_inputs
 download_calibration_inputs("{calibration_dir}")
 print("Done")
 """,
-            ],
-            text=True,
-            env=os.environ.copy(),
-        )
-        if result.returncode != 0:
-            raise RuntimeError(f"Download failed: {result.stderr}")
-        staging_volume.commit()
-        print("Calibration inputs downloaded and cached on volume")
-    else:
-        print("Using cached calibration inputs from volume")
+        ],
+        text=True,
+        env=os.environ.copy(),
+    )
+    if result.returncode != 0:
+        raise RuntimeError(f"Download failed: {result.stderr}")
+    staging_volume.commit()
+    print("Calibration inputs downloaded")
 
     calibration_inputs = {
         "weights": str(weights_path),