fix(lambda): strip Sentry stack-frame locals

lambdas/shared/sentry_init.py

@@ -2,8 +2,10 @@
 
 Imported for side effect from each handler. ``init_sentry()`` is a no-op when
 ``SENTRY_DSN`` is unset so pytest, local invokes, and a missing HCP var never
-talk to Sentry. ``before_send`` strips auth headers and drops request/extra
+talk to Sentry. ``before_send`` strips auth headers, drops request/extra keys
-keys that can hold MIME bodies, Bedrock prompts, or HMAC secret material.
+that can hold MIME bodies, Bedrock prompts, or HMAC secret material, and
+removes exception stack-frame locals. ``include_local_variables=False`` keeps
+those locals out of the event in the first place.
 """
 
 import os
@@ -63,6 +65,38 @@ def _scrub_headers(headers):
     return headers
 
 
+def _stacktraces(event):
+    traces = []
+    stacktrace = event.get("stacktrace")
+    if isinstance(stacktrace, dict):
+        traces.append(stacktrace)
+    for section in ("exception", "threads"):
+        container = event.get(section)
+        if not isinstance(container, dict):
+            continue
+        values = container.get("values")
+        if not isinstance(values, list):
+            continue
+        for item in values:
+            if not isinstance(item, dict):
+                continue
+            inner = item.get("stacktrace")
+            if isinstance(inner, dict):
+                traces.append(inner)
+    return traces
+
+
+def _strip_stack_locals(event):
+    """Drop frame locals. Names like ``raw``/``item`` still hold MIME or secrets."""
+    for stacktrace in _stacktraces(event):
+        frames = stacktrace.get("frames")
+        if not isinstance(frames, list):
+            continue
+        for frame in frames:
+            if isinstance(frame, dict):
+                frame.pop("vars", None)
+
+
 def _before_send(event, _hint):
     request = event.get("request")
     if isinstance(request, dict):
@@ -78,6 +112,7 @@ def _before_send(event, _hint):
             lower = str(key).lower()
             if any(needle in lower for needle in _DROP_EXTRA_NEEDLES):
                 extra.pop(key, None)
+    _strip_stack_locals(event)
     return event
 
 
@@ -89,6 +124,7 @@ def init_sentry():
         dsn=dsn,
         integrations=[AwsLambdaIntegration(timeout_warning=True)],
         send_default_pii=False,
+        include_local_variables=False,
         enable_logs=False,
         traces_sample_rate=0.0,
         before_send=_before_send,

tests/test_sentry_init.py

@@ -39,6 +39,7 @@ def test_set_dsn_inits_lambda_integration(sentry_mod, monkeypatch):
     kwargs = mocked.call_args.kwargs
     assert kwargs["dsn"] == "https://key@o1.ingest.sentry.io/1"
     assert kwargs["send_default_pii"] is False
+    assert kwargs["include_local_variables"] is False
     assert kwargs["enable_logs"] is False
     assert kwargs["traces_sample_rate"] == 0.0
     assert kwargs["before_send"] is sentry_mod._before_send
@@ -100,3 +101,44 @@ def test_before_send_drops_body_prompt_and_secret_keys(sentry_mod):
     assert "bedrock_prompt" not in out["extra"]
     assert "hmac_secret" not in out["extra"]
     assert out["extra"]["po_number"] == "123"
+
+
+def test_before_send_drops_exception_and_thread_frame_locals(sentry_mod):
+    event = {
+        "exception": {
+            "values": [
+                {
+                    "stacktrace": {
+                        "frames": [
+                            {
+                                "function": "handler",
+                                "vars": {
+                                    "raw_email": "From: attacker",
+                                    "SecretString": "aabbcc",
+                                },
+                            }
+                        ]
+                    }
+                }
+            ]
+        },
+        "threads": {
+            "values": [
+                {
+                    "stacktrace": {
+                        "frames": [
+                            {"function": "extract_with_claude", "vars": {"prompt": "EXTRACT"}}
+                        ]
+                    }
+                }
+            ]
+        },
+        "stacktrace": {
+            "frames": [{"function": "save_work_order", "vars": {"item": {"wo": 1}}}]
+        },
+    }
+    out = sentry_mod._before_send(event, {})
+    assert "vars" not in out["exception"]["values"][0]["stacktrace"]["frames"][0]
+    assert "vars" not in out["threads"]["values"][0]["stacktrace"]["frames"][0]
+    assert "vars" not in out["stacktrace"]["frames"][0]
+    assert out["exception"]["values"][0]["stacktrace"]["frames"][0]["function"] == "handler"