diff --git a/mempalace/project_scanner.py b/mempalace/project_scanner.py
index f426e8f..eaab560 100644
--- a/mempalace/project_scanner.py
+++ b/mempalace/project_scanner.py
@@ -164,18 +164,19 @@ def _parse_gomod(path: Path) -> Optional[str]:
     return None
 
 
-MANIFEST_PARSERS = {
-    "package.json": _parse_package_json,
-    "pyproject.toml": _parse_pyproject,
-    "Cargo.toml": _parse_cargo,
-    "go.mod": _parse_gomod,
-}
 MANIFEST_PRIORITY = {
     "pyproject.toml": 0,
     "package.json": 1,
     "Cargo.toml": 2,
     "go.mod": 3,
 }
+UNKNOWN_MANIFEST_PRIORITY = 999
+MANIFEST_PARSERS = {
+    "package.json": _parse_package_json,
+    "pyproject.toml": _parse_pyproject,
+    "Cargo.toml": _parse_cargo,
+    "go.mod": _parse_gomod,
+}
 
 
 # ==================== GIT HELPERS ====================
@@ -318,7 +319,7 @@ def _manifest_sort_key(entry: tuple[str, str, Path], repo_root: Path) -> tuple[i
     except ValueError:
         depth = MAX_DEPTH + 1
         rel_str = manifest_dir.as_posix()
-    return (depth, MANIFEST_PRIORITY.get(manifest_file, len(MANIFEST_PRIORITY)), rel_str)
+    return (depth, MANIFEST_PRIORITY.get(manifest_file, UNKNOWN_MANIFEST_PRIORITY), rel_str)
 
 
 def find_git_repos(root: Path, max_depth: int = MAX_DEPTH) -> list[Path]:
diff --git a/tests/test_project_scanner.py b/tests/test_project_scanner.py
index 821f527..4fcb6dd 100644
--- a/tests/test_project_scanner.py
+++ b/tests/test_project_scanner.py
@@ -27,6 +27,8 @@ from mempalace.project_scanner import (
     to_detected_dict,
 )
 
+GIT_ENV_ALLOWLIST = ("PATH", "HOME", "SystemRoot", "ComSpec", "TMPDIR", "TEMP", "TMP")
+
 
 # ── manifest parsers ────────────────────────────────────────────────────
 
@@ -228,7 +230,7 @@ def _git_test_env(name: str, email: str) -> dict[str, str]:
         "GIT_COMMITTER_NAME": name,
         "GIT_COMMITTER_EMAIL": email,
     }
-    for key in ("PATH", "HOME", "SystemRoot", "ComSpec", "TMPDIR", "TEMP", "TMP"):
+    for key in GIT_ENV_ALLOWLIST:
         value = os.environ.get(key)
         if value:
             env[key] = value