fix(preprocess): restrict DWH root claims to writers

harness/tht/cli/schema_cmd.py

@@ -39,6 +39,8 @@ def _load_config_or_exit(config: Path):
 def physical_path(cfg) -> Path:
     from tht.jobs.dwh_pipeline import resolve_dwh_snapshot
 
+    if not (cfg.paths.artifacts.parent / ".tht-dwh").exists():
+        return cfg.paths.artifacts / "mschema" / "physical.yaml"
     return resolve_dwh_snapshot(cfg).physical
 
 
@@ -92,9 +94,9 @@ def introspect_cmd(
             )
             return
     try:
-        from tht.jobs.dwh_pipeline import active_generation_dir
+        from tht.jobs.dwh_pipeline import resolve_dwh_snapshot
 
-        if active_generation_dir(cfg.paths.artifacts.parent) is None:
+        if resolve_dwh_snapshot(cfg).generation is None:
             phys = refresh_catalog(cfg)
         else:
             from tht.cli.preprocess_cmd import run_dwh_from_config