diff --git a/app/gitea_client.py b/app/gitea_client.py
index 8909784..f1f81b0 100644
--- a/app/gitea_client.py
+++ b/app/gitea_client.py
@@ -172,8 +172,10 @@ class GiteaClient:
     ) -> list[dict]:
         """Get issues for a repo (paginated, cached).
 
-        Note: Gitea's issues endpoint also returns pull requests; each
-        PR carries a "pull_request" key and callers filter on it.
+        Note: Gitea's issues endpoint also returns pull requests; a
+        PR carries a non-null "pull_request" object, a plain issue
+        carries "pull_request": null — callers filter on truthiness
+        (see app.main._is_issue).
         """
         key = f"issues:{owner}/{repo}:{state}"
         cached = self._cache_get(key)
diff --git a/app/main.py b/app/main.py
index 8fb8676..4c4bc1a 100644
--- a/app/main.py
+++ b/app/main.py
@@ -323,8 +323,15 @@ def classify_repos(
 
 
 def _is_issue(item: dict) -> bool:
-    """Gitea's issues endpoint also returns PRs; they carry this key."""
-    return "pull_request" not in item
+    """True for issues, False for pull requests.
+
+    Gitea's issues endpoint also returns PRs. A PR carries a
+    ``pull_request`` *object*; a plain issue carries the same key
+    with value ``null`` (verified against Gitea 1.27.3). Testing key
+    presence therefore classifies every real issue as a PR and
+    empties the board — test the value's truthiness instead.
+    """
+    return not item.get("pull_request")
 
 
 def _merge_issues_with_board(