diff --git a/bin/stuck_check.py b/bin/stuck_check.py
new file mode 100644
index 0000000..418a130
--- /dev/null
+++ b/bin/stuck_check.py
@@ -0,0 +1,32 @@
+"""Detect if autoresearch experiments are stuck on the same files."""
+import sys
+import os
+
+sys.path.insert(0, os.path.dirname(__file__))
+from log_append import read_entries
+
+
+def is_stuck(project: str, entries: list, window: int = 3) -> bool:
+    """Return True if the last `window` entries for `project` all touch the same non-empty set of files."""
+    project_entries = [e for e in entries if e.get('project') == project]
+    if len(project_entries) < window:
+        return False
+    recent = project_entries[-window:]
+    file_sets = [frozenset(e.get('files_changed') or []) for e in recent]
+    # Empty file sets don't count as stuck
+    if file_sets[0] == frozenset():
+        return False
+    return len(set(file_sets)) == 1
+
+
+if __name__ == '__main__':
+    project = sys.argv[1] if len(sys.argv) > 1 else ''
+    if not project:
+        print("Usage: stuck_check.py <project-name>", file=sys.stderr)
+        sys.exit(2)
+    entries = read_entries()
+    if is_stuck(project, entries):
+        print(f"STUCK: project '{project}' has touched the same files 3 times in a row")
+        sys.exit(1)
+    print("ok")
+    sys.exit(0)
diff --git a/tests/test_stuck.py b/tests/test_stuck.py
new file mode 100644
index 0000000..e335ee8
--- /dev/null
+++ b/tests/test_stuck.py
@@ -0,0 +1,55 @@
+import sys
+sys.path.insert(0, 'bin')
+from stuck_check import is_stuck
+
+def test_not_stuck_with_different_files():
+    entries = [
+        {'project': 'x', 'files_changed': ['a.go']},
+        {'project': 'x', 'files_changed': ['b.go']},
+        {'project': 'x', 'files_changed': ['c.go']},
+    ]
+    assert is_stuck('x', entries) is False
+
+def test_stuck_when_same_files_3_times():
+    entries = [
+        {'project': 'x', 'files_changed': ['a.go', 'b.go']},
+        {'project': 'x', 'files_changed': ['a.go', 'b.go']},
+        {'project': 'x', 'files_changed': ['a.go', 'b.go']},
+    ]
+    assert is_stuck('x', entries) is True
+
+def test_not_stuck_with_fewer_than_3_entries():
+    entries = [
+        {'project': 'x', 'files_changed': ['a.go']},
+        {'project': 'x', 'files_changed': ['a.go']},
+    ]
+    assert is_stuck('x', entries) is False
+
+def test_only_checks_matching_project():
+    entries = [
+        {'project': 'y', 'files_changed': ['a.go']},
+        {'project': 'y', 'files_changed': ['a.go']},
+        {'project': 'y', 'files_changed': ['a.go']},
+        {'project': 'x', 'files_changed': ['a.go']},
+        {'project': 'x', 'files_changed': ['a.go']},
+    ]
+    assert is_stuck('x', entries) is False  # only 2 entries for x
+
+def test_not_stuck_when_files_empty():
+    """Empty file sets don't count as stuck — agent may not have changed anything."""
+    entries = [
+        {'project': 'x', 'files_changed': []},
+        {'project': 'x', 'files_changed': []},
+        {'project': 'x', 'files_changed': []},
+    ]
+    assert is_stuck('x', entries) is False
+
+def test_order_matters_only_last_3():
+    """Only the last 3 entries matter."""
+    entries = [
+        {'project': 'x', 'files_changed': ['a.go']},
+        {'project': 'x', 'files_changed': ['a.go']},
+        {'project': 'x', 'files_changed': ['a.go']},
+        {'project': 'x', 'files_changed': ['b.go']},  # most recent: different
+    ]
+    assert is_stuck('x', entries) is False