diff --git a/codewiki/src/be/dependency_analyzer/analysis/call_graph_analyzer.py b/codewiki/src/be/dependency_analyzer/analysis/call_graph_analyzer.py
index 1cc33ec0..b95c93f8 100644
--- a/codewiki/src/be/dependency_analyzer/analysis/call_graph_analyzer.py
+++ b/codewiki/src/be/dependency_analyzer/analysis/call_graph_analyzer.py
@@ -28,8 +28,15 @@
 logger = logging.getLogger(__name__)
 
 
-class TimeoutError(Exception):
-    """Raised when file parsing exceeds timeout."""
+class TimeoutError(BaseException):
+    """Raised when file parsing exceeds timeout.
+
+    A ``BaseException`` on purpose: the language analyzers wrap many small
+    steps in ``except Exception`` blocks.  If the alarm fired inside one of
+    them, the error was swallowed, the alarm was already spent, and a slow
+    file (e.g. a multi-megabyte vendored JS bundle) ran forever.  Only
+    ``_analyze_code_file`` catches it.
+    """
 
 
 @contextmanager
diff --git a/tests/test_parse_timeout.py b/tests/test_parse_timeout.py
new file mode 100644
index 00000000..205015c3
--- /dev/null
+++ b/tests/test_parse_timeout.py
@@ -0,0 +1,41 @@
+"""The per-file parse timeout must not be swallowed by an analyzer's own
+``except Exception`` blocks."""
+
+import signal
+import time
+
+import pytest
+
+from codewiki.src.be.dependency_analyzer.analysis import call_graph_analyzer
+from codewiki.src.be.dependency_analyzer.analysis.call_graph_analyzer import (
+    CallGraphAnalyzer,
+)
+
+pytestmark = pytest.mark.skipif(
+    not hasattr(signal, "SIGALRM"), reason="the timeout relies on SIGALRM"
+)
+
+
+def _swallowing_analyzer(self, file_path, content, repo_dir):
+    # Mimics a language analyzer that guards each small step with
+    # ``except Exception`` and loops for a very long time.
+    deadline = time.monotonic() + 30
+    while time.monotonic() < deadline:
+        try:
+            time.sleep(0.01)
+        except Exception:  # noqa: BLE001
+            pass
+
+
+def test_timeout_escapes_except_exception(tmp_path, monkeypatch):
+    (tmp_path / "slow.js").write_text("f();\n", encoding="utf-8")
+    monkeypatch.setattr(CallGraphAnalyzer, "_analyze_javascript_file", _swallowing_analyzer)
+
+    real_timeout = call_graph_analyzer.timeout
+    monkeypatch.setattr(call_graph_analyzer, "timeout", lambda seconds: real_timeout(1))
+
+    started = time.monotonic()
+    CallGraphAnalyzer()._analyze_code_file(
+        str(tmp_path), {"path": "slow.js", "language": "javascript"}
+    )
+    assert time.monotonic() - started < 10