fix: count build file trees as pinned

check_source_paths read the trees profiles pin from source and upstream
only, so the two platform trees the record now holds for pin_build
files read as orphaned and the record as stale.

scripts/check_freshness.py

@@ -1492,6 +1492,11 @@ def check_source_paths(profiles: dict) -> Finding:
         sitesources.tree_key(repo, pin)
         for profile in profiles.values() if sitesources.cited_paths(profile)
         for repo, pin in sitesources.profile_trees(profile)
+    } | {
+        # The platform build files pin_build names, linked from a page too.
+        sitesources.tree_key(repo, pin)
+        for profile in profiles.values()
+        for repo, pin, _path in sitesources.build_files(profile)
     }
     try:
         recorded = set(json.loads(sitesources.SOURCE_PATHS.read_text(encoding="utf-8")))

tests/test_site_integration.py

@@ -117,6 +117,21 @@ class SourcePathsFreshness(unittest.TestCase):
         finding = check_freshness.check_source_paths(profiles)
         self.assertEqual(finding.status, check_freshness.OK, finding.detail)
 
+    def test_a_recorded_build_file_tree_is_pinned(self):
+        """The record holds the platform trees pin_build reads at a commit,
+        and the check called them orphaned."""
+        import sitesources  # noqa: PLC0415
+
+        pin = "a" * 40
+        profile = {"pin_build": [{"repo": "https://github.com/o/r", "revision": pin,
+                                  "path": "p.mk"}]}
+        with tempfile.TemporaryDirectory() as tmp:
+            path = Path(tmp) / "source-paths.json"
+            path.write_text(json.dumps({f"github.com/o/r@{pin}": ["p.mk"]}), encoding="utf-8")
+            with mock.patch.object(sitesources, "SOURCE_PATHS", path):
+                finding = check_freshness.check_source_paths({"p": profile})
+        self.assertEqual(finding.status, check_freshness.OK, finding.detail)
+
     def test_a_moved_pin_is_stale(self):
         profile = _profile("geolith")
         moved = dict(profile, source_commit="f" * 40, upstream_commit="e" * 40)