fix: stabilize Polygon config loading and sync

tests/test_converter.py

@@ -180,3 +180,45 @@ class TestFileRoundtrip:
             assert len(loaded["cfsParams"]) == 2
         finally:
             os.unlink(fname)
+
+
+class TestGenerationSync:
+    """The CLI output directory should match its source after a clean run."""
+
+    def test_main_removes_yaml_missing_from_source(self, tmp_path, monkeypatch, dummy_yaml):
+        source_dir = tmp_path / "source"
+        output_dir = tmp_path / "output"
+        source_dir.mkdir()
+        output_dir.mkdir()
+        with open(source_dir / "1_dummy.yaml", "w", encoding="utf-8") as source_file:
+            yaml.safe_dump(dummy_yaml, source_file, allow_unicode=True)
+        (output_dir / "27_obsolete.yaml").write_text("old: true\n", encoding="utf-8")
+        (output_dir / "keep.txt").write_text("not YAML\n", encoding="utf-8")
+
+        monkeypatch.setattr(
+            sys,
+            "argv",
+            ["from_stands.py", str(source_dir), str(output_dir)],
+        )
+        from_stands.main()
+
+        assert (output_dir / "1_dummy.yaml").is_file()
+        assert not (output_dir / "27_obsolete.yaml").exists()
+        assert (output_dir / "keep.txt").is_file()
+
+    def test_main_keeps_existing_yaml_when_conversion_fails(self, tmp_path, monkeypatch):
+        source_dir = tmp_path / "source"
+        output_dir = tmp_path / "output"
+        source_dir.mkdir()
+        output_dir.mkdir()
+        (source_dir / "broken.yaml").write_text("broken: [", encoding="utf-8")
+        (output_dir / "27_obsolete.yaml").write_text("old: true\n", encoding="utf-8")
+
+        monkeypatch.setattr(
+            sys,
+            "argv",
+            ["from_stands.py", str(source_dir), str(output_dir)],
+        )
+        from_stands.main()
+
+        assert (output_dir / "27_obsolete.yaml").is_file()

tests/test_loader.py

@@ -0,0 +1,71 @@
+"""Regression tests for startup configuration path resolution."""
+
+import os
+import subprocess
+import sys
+from pathlib import Path
+
+import pytest
+
+
+POLYGON_ROOT = Path(__file__).resolve().parents[1]
+SITE_DIR = POLYGON_ROOT / "site"
+
+
+@pytest.mark.parametrize("working_dir", [POLYGON_ROOT, SITE_DIR])
+def test_loader_finds_stand_yaml_independent_of_working_directory(working_dir):
+    """Exercise a fresh import from both documented launch directories.
+
+    A subprocess isolates module-level environment parsing and import-time YAML
+    loading, which is the exact behavior used when the WSGI process starts.
+    """
+    env = os.environ.copy()
+    env["POLYGON_STANDS"] = (
+        "dev:services/dev,test:services/test,prod:services/prod"
+    )
+    python_path = str(SITE_DIR)
+    if env.get("PYTHONPATH"):
+        python_path += os.pathsep + env["PYTHONPATH"]
+    env["PYTHONPATH"] = python_path
+
+    subprocess.run(
+        [
+            sys.executable,
+            "-c",
+            (
+                "import app; "
+                "assert set(app._cfg.STANDS) == {'dev', 'test', 'prod'}; "
+                "assert app.app.test_client().get('/health').status_code == 200"
+            ),
+        ],
+        cwd=working_dir,
+        env=env,
+        check=True,
+        timeout=10,
+    )
+
+
+def test_loader_finds_default_services_from_repository_root():
+    """The no-env default must also work with the platform's root CWD."""
+    env = os.environ.copy()
+    env.pop("POLYGON_STANDS", None)
+    python_path = str(SITE_DIR)
+    if env.get("PYTHONPATH"):
+        python_path += os.pathsep + env["PYTHONPATH"]
+    env["PYTHONPATH"] = python_path
+
+    subprocess.run(
+        [
+            sys.executable,
+            "-c",
+            (
+                "import app; "
+                "assert set(app._cfg.STANDS) == {'default'}; "
+                "assert app.app.test_client().get('/health').status_code == 200"
+            ),
+        ],
+        cwd=POLYGON_ROOT,
+        env=env,
+        check=True,
+        timeout=10,
+    )