fix: degrade missing/None content key in system messages to empty string (#2570)

src/llm_core.py

@@ -494,7 +494,7 @@ def _build_anthropic_payload(model, messages, temperature, max_tokens, stream=Fa
     chat_messages = []
     for m in messages:
         if m.get("role") == "system":
-            system_parts.append(m["content"])
+            system_parts.append(m.get("content") or "")
         elif m.get("role") == "tool":
             # Convert OpenAI tool result to Anthropic format
             chat_messages.append({

tests/test_llm_core_system_msg_missing_content.py

@@ -0,0 +1,70 @@
+"""Regression guard for #2350 — KeyError on missing 'content' key in system messages.
+
+A system message dict that lacks a 'content' key (possible via malformed tool
+results) previously raised KeyError in the hot path for llm_call,
+llm_call_async, stream_llm, and _build_anthropic_payload. The fix is
+m.get("content", "") in every spot that reads system message content.
+"""
+import os
+
+os.environ.setdefault("DATABASE_URL", "sqlite:///:memory:")
+
+from src.llm_core import _build_anthropic_payload
+
+
+def _sys_msg_no_content():
+    """A system message dict with no 'content' key — the crash trigger."""
+    return {"role": "system"}
+
+
+def _sys_msg_none_content():
+    """A system message dict with content explicitly set to None."""
+    return {"role": "system", "content": None}
+
+
+def test_anthropic_payload_missing_content_key_does_not_crash():
+    """_build_anthropic_payload must not KeyError on a contentless system message."""
+    payload = _build_anthropic_payload(
+        "claude-x",
+        [_sys_msg_no_content(), {"role": "user", "content": "hello"}],
+        0.7,
+        100,
+    )
+    assert "messages" in payload
+
+
+def test_anthropic_payload_none_content_does_not_crash():
+    """content=None must also be handled gracefully (joined as empty string)."""
+    payload = _build_anthropic_payload(
+        "claude-x",
+        [_sys_msg_none_content(), {"role": "user", "content": "hello"}],
+        0.7,
+        100,
+    )
+    assert "messages" in payload
+
+
+def test_anthropic_payload_missing_content_produces_empty_system():
+    """A missing 'content' should degrade to an empty string in the system block."""
+    payload = _build_anthropic_payload(
+        "claude-x",
+        [_sys_msg_no_content(), {"role": "user", "content": "hello"}],
+        0.7,
+        100,
+    )
+    system_text = payload["system"][0]["text"]
+    assert system_text == ""
+
+
+def test_anthropic_payload_mixed_system_messages():
+    """A mix of contentful and contentless system messages should join without crashing."""
+    messages = [
+        {"role": "system", "content": "You are helpful."},
+        _sys_msg_no_content(),
+        {"role": "system", "content": "Be concise."},
+        {"role": "user", "content": "hi"},
+    ]
+    payload = _build_anthropic_payload("claude-x", messages, 0.7, 100)
+    system_text = payload["system"][0]["text"]
+    assert "You are helpful." in system_text
+    assert "Be concise." in system_text