diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1847804d..8927cc0d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -179,6 +179,8 @@ per-file diff commands.
   (`json|table|plain` for search, `json|plain` for detail) and exit 1 with `{ error, code: "BAD_ARG" }`
   on invalid options.
 
+- **Upstream checks report incomplete comparisons** (#583) - missing base or head framework files now remain visible as incomplete comparisons instead of being reported as unchanged.
+
 - **`jobdanmark-search detail` no longer keeps a malformed closing tag as text on the
   rendered-HTML branch** (#525, `detail.ts`, `tests/detail-parsing.test.ts`) - a live page wrote
   its Jobtype item as `Fuldtid </ li >`, and because `node-html-parser` does not recognise a
diff --git a/tests/test_check_upstream_updates.py b/tests/test_check_upstream_updates.py
index 9c92e062..e1bed589 100644
--- a/tests/test_check_upstream_updates.py
+++ b/tests/test_check_upstream_updates.py
@@ -160,5 +160,37 @@ class UpstreamRefMissingFileTests(UpstreamCheckerRepoFixture):
         self.assertIn("[WARNING]", result.stdout)
 
 
+class IncompleteComparisonTests(UpstreamCheckerRepoFixture):
+    def setUp(self):
+        super().setUp()
+        self.add_remote("upstream", TEMPLATE_URL)
+        self.materialize_remote_ref("upstream")
+
+    def test_missing_local_file_does_not_report_all_files_up_to_date(self):
+        (self.root / "AGENTS.md").unlink()
+
+        result = self.run_checker()
+
+        self.assertEqual(result.returncode, 0, result.stdout + result.stderr)
+        self.assertIn("AGENTS.md", result.stdout)
+        self.assertIn("[WARNING] Framework check incomplete", result.stdout)
+        self.assertNotIn("[OK]", result.stdout)
+
+    def test_missing_upstream_marker_does_not_report_all_files_up_to_date(self):
+        agents = self.root / "AGENTS.md"
+        agents.write_text("# Upstream guidelines without a version marker\n", encoding="utf-8")
+        subprocess.run(["git", "add", "AGENTS.md"], cwd=self.root, check=True, capture_output=True)
+        subprocess.run(["git", "commit", "-qm", "remove upstream version marker"], cwd=self.root, check=True, capture_output=True)
+        self.materialize_remote_ref("upstream")
+        agents.write_text(FRONTMATTER, encoding="utf-8")
+
+        result = self.run_checker()
+
+        self.assertEqual(result.returncode, 0, result.stdout + result.stderr)
+        self.assertIn("AGENTS.md", result.stdout)
+        self.assertIn("[WARNING] Framework check incomplete", result.stdout)
+        self.assertNotIn("[OK]", result.stdout)
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/tools/check_upstream_updates.py b/tools/check_upstream_updates.py
index f1595b93..d5271546 100755
--- a/tools/check_upstream_updates.py
+++ b/tools/check_upstream_updates.py
@@ -119,7 +119,7 @@ def main() -> int:
     for rel_path in FRAMEWORK_FILES:
         local_path = ROOT / rel_path
         if not local_path.exists():
-            print(f"Local file missing: {rel_path}")
+            errors.append(f"Local file missing: {rel_path}")
             continue
 
         # Get local version
@@ -145,6 +145,7 @@ def main() -> int:
             errors.append(f"Local file {rel_path} is missing 'framework_version' in frontmatter.")
             continue
         if not upstream_ver:
+            errors.append(f"Upstream file {rel_path} is missing 'framework_version' in frontmatter.")
             continue
             
         if parse_semver(upstream_ver) > parse_semver(local_ver):