fix(platform): emit W3C-compliant traceparent so the gateway accepts it

build_trace_context_headers emitted x-uipath-traceparent-id as
"00-{trace}-{span}" with a 32-hex span id and no trace-flags segment. The
LLM Gateway parses this header strictly (UiPath.Tracing.TraceParent.TryParse):
it requires exactly four segments {version}-{32-hex trace}-{16-hex span}-{flags}
and a 16-hex span id. The malformed header was rejected, so the gateway
synthesized a fresh root trace for every LLM call and dropped the inbound
baggage — the gateway's completion (audit) span ended up under a different
traceId with a null parent, orphaned from the agent run, and the jobKey/source
baggage this PR adds never reached the gateway.

Fix: format the span id as 16 hex (`016x`, a span id is 64-bit) and append the
`-01` trace-flags segment. Verified safe for the other consumer (the Agents
backend parser is lenient: >=3 parts, no span-length check). Updated the test
to assert the correct 4-segment / 16-hex shape.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: RunnanJia

packages/uipath-platform/src/uipath/platform/chat/llm_trace_context.py

@@ -34,8 +34,14 @@ def build_trace_context_headers(
     ctx = span.get_span_context()
     if config_trace_id and ctx and ctx.span_id:
         trace_id = _SpanUtils.normalize_trace_id(config_trace_id)
-        span_id = format(ctx.span_id, "032x")
-        headers["x-uipath-traceparent-id"] = f"00-{trace_id}-{span_id}"
+        # An OTEL span id is 64-bit => 16 lowercase hex chars, and the W3C traceparent
+        # requires the trailing trace-flags segment. The LLM Gateway's strict parser
+        # (UiPath.Tracing.TraceParent.TryParse) rejects the header unless it is exactly
+        # {version}-{32-hex trace}-{16-hex span}-{2-hex flags}; on rejection the gateway
+        # synthesizes a fresh root trace and drops inbound baggage, orphaning the audit
+        # span from the caller's trace. Emitting 32-hex span / no flags was the bug.
+        span_id = format(ctx.span_id, "016x")
+        headers["x-uipath-traceparent-id"] = f"00-{trace_id}-{span_id}-01"
 
     baggage_parts: list[str] = list(extra_baggage) if extra_baggage else []
     if folder_key := UiPathConfig.folder_key:

packages/uipath-platform/tests/services/test_llm_trace_context.py

@@ -44,7 +44,9 @@ def setup_method(self) -> None:
     def test_traceparent_from_config_and_span(self) -> None:
         span = _make_span()
         ctx = span.get_span_context()
-        expected_span_id = format(ctx.span_id, "032x")
+        # OTEL span id is 64-bit => 16 hex chars; traceparent carries the trailing flags
+        # segment. The gateway's strict W3C parser requires exactly this shape.
+        expected_span_id = format(ctx.span_id, "016x")
         config_trace = "abcdef1234567890abcdef1234567890"
         env = {"UIPATH_TRACE_ID": config_trace}
         with (
@@ -58,12 +60,13 @@ def test_traceparent_from_config_and_span(self) -> None:
 
         assert "x-uipath-traceparent-id" in headers
         value = headers["x-uipath-traceparent-id"]
-        assert value == f"00-{config_trace}-{expected_span_id}"
+        assert value == f"00-{config_trace}-{expected_span_id}-01"
         parts = value.split("-")
-        assert len(parts) == 3
+        assert len(parts) == 4
         assert parts[0] == "00"
         assert len(parts[1]) == 32
-        assert len(parts[2]) == 32
+        assert len(parts[2]) == 16
+        assert parts[3] == "01"
 
     def test_no_traceparent_without_config_trace_id(self) -> None:
         headers = build_trace_context_headers()