diff --git a/src/homemaker_layout/fitness_cmd.py b/src/homemaker_layout/fitness_cmd.py
new file mode 100644
index 0000000..d376bfa
--- /dev/null
+++ b/src/homemaker_layout/fitness_cmd.py
@@ -0,0 +1,114 @@
+"""homemaker-fitness — native Python replacement for urb-fitness.pl.
+
+Scores .dom files using the native fitness engine (fitness.Fitness) and writes
+.score / .fails side-car files in the same format as urb-fitness.pl.
+
+Usage (module):
+  python -m homemaker_layout.fitness_cmd [dom1.dom dom2.dom ...]
+
+When installed via pip install -e .:
+  homemaker-fitness [dom1.dom dom2.dom ...]
+
+If no arguments are given, all *.dom files in the current directory are scored.
+
+Scoring is skipped for a file if its .score and .fails side-cars already exist
+and are both newer than the .dom file and the config files — set FORCE_UPDATE=1
+to override (matches urb-fitness.pl behaviour).
+
+Score is written to <dom>.score as a 40-decimal-place float; failures are
+written one-per-line to <dom>.fails.  Score is also printed to stderr.
+"""
+
+from __future__ import annotations
+
+import os
+import sys
+from pathlib import Path
+
+import yaml
+
+from . import dom as dom_mod
+from . import geometry
+from .fitness import Fitness, load_config
+
+
+def _config_mtime(directory: Path) -> float:
+    """Latest mtime of any patterns/costs config file visible to this directory."""
+    mtime = 0.0
+    for name in ("patterns.config", "costs.config"):
+        for p in (directory.parent / name, directory / name):
+            if p.is_file():
+                t = p.stat().st_mtime
+                if t > mtime:
+                    mtime = t
+    return mtime
+
+
+def _should_score(dom_path: Path, config_mtime: float) -> bool:
+    """Return True if the dom needs (re-)scoring."""
+    if os.environ.get("FORCE_UPDATE") or os.environ.get("DEBUG"):
+        return True
+    score_p = Path(f"{dom_path}.score")
+    fails_p = Path(f"{dom_path}.fails")
+    if not score_p.exists() or not fails_p.exists():
+        return True
+    dom_mtime = dom_path.stat().st_mtime
+    score_mtime = score_p.stat().st_mtime
+    if score_mtime < dom_mtime or score_mtime < config_mtime:
+        return True
+    if fails_p.stat().st_mtime < dom_mtime:
+        return True
+    return False
+
+
+def score_file(dom_path: Path, fitness: Fitness) -> float:
+    """Score one .dom file, write side-cars, return score."""
+    root = dom_mod.load(str(dom_path))
+    geometry.clear_cache()
+    score, failures = fitness.score_with_fails(root)
+
+    score_str = f"{score:.40f}"
+    score_p = Path(f"{dom_path}.score")
+    score_p.unlink(missing_ok=True)
+    score_p.write_text(score_str + "\n")
+
+    fails_p = Path(f"{dom_path}.fails")
+    fails_p.unlink(missing_ok=True)
+    fails_p.write_text("\n".join(failures) + ("\n" if failures else ""))
+
+    return score
+
+
+def main(argv=None) -> int:
+    args = (argv or sys.argv)[1:]
+
+    cwd = Path.cwd()
+    conf, cost = load_config(cwd)
+    fitness = Fitness(conf, cost)
+    cfg_mtime = _config_mtime(cwd)
+
+    if args:
+        dom_paths = [Path(a) for a in args if a.endswith(".dom")]
+    else:
+        dom_paths = sorted(cwd.glob("*.dom"))
+        print("Calculating fitness for all files in current folder", file=sys.stderr)
+
+    for dom_path in dom_paths:
+        dom_path = Path(dom_path)
+        if not dom_path.exists():
+            print(f"File not found, skipping: {dom_path}", file=sys.stderr)
+            continue
+        if not _should_score(dom_path, cfg_mtime):
+            continue
+        try:
+            score = score_file(dom_path, fitness)
+        except Exception as exc:
+            print(f"Error scoring {dom_path}: {exc}", file=sys.stderr)
+            continue
+        print(f"{score:.40f}", file=sys.stderr)
+
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())