Make header lookup case-insensitive

Normalize the requested header name before comparing so mixed-case callers still match HTTP headers case-insensitively.

Constraint: Copilot review comment on PR #128 flagged _get_header as unexpectedly case-sensitive for mixed-case lookup names.

Rejected: broader header abstraction | a one-line normalization preserves the current helper boundary.

Confidence: high

Scope-risk: narrow

Tested: uv run --extra server pytest tests/unittests/server/test_error_utils.py tests/unittests/server/test_invoker.py tests/unittests/server/test_agui_protocol.py tests/unittests/integration/test_langgraph_events.py -q => 102 passed, 1 warning

Tested: uv run --extra server pytest tests/unittests/integration/test_langgraph_to_agent_event.py -q => 32 passed

Tested: git diff --check && uv run ruff check agentrun/server/error_utils.py tests/unittests/server/test_error_utils.py => passed

Change-Id: I23e62a3b01e88c1b39f8669f89490b1c7f5e9ddf
Co-developed-by: Codex <noreply@openai.com>
Not-tested: full repository test suite and remote CI pending
Signed-off-by: congxiao.wxx <congxiao.wxx@alibaba-inc.com>

Author: congxiao-wxx

agentrun/server/error_utils.py

@@ -131,9 +131,10 @@ def _get_value(obj: Any, name: str) -> Optional[Any]:
 
 
 def _get_header(headers: Any, name: str) -> Optional[Any]:
+    target = str(name).lower()
     if isinstance(headers, dict):
         for key, value in headers.items():
-            if str(key).lower() == name:
+            if str(key).lower() == target:
                 return value
         return None
     get = getattr(headers, "get", None)

tests/unittests/server/test_error_utils.py

@@ -0,0 +1,9 @@
+"""Tests for server error helpers."""
+
+from agentrun.server.error_utils import _get_header
+
+
+def test_get_header_matches_name_case_insensitively():
+    headers = {"x-trace-id": "trace-123"}
+
+    assert _get_header(headers, "X-Trace-ID") == "trace-123"