fix(telemetry): add resolved_trace_id property to eliminate trace_id inconsistencies

Add computed property to BaseTraceInfo that provides intelligent fallback:
1. External trace_id (from X-Trace-Id header)
2. workflow_run_id (for workflow-related traces)
3. message_id (as final fallback)

This ensures attribute dify.trace_id always matches log-level trace_id,
eliminating inconsistencies where attribute was null but log-level had value.

Changes:
- Add resolved_trace_id property to BaseTraceInfo (trace_entity.py)
- Replace 4 direct trace_id attribute assignments with resolved_trace_id
- Add trace_id_source parameter to 5 emit_metric_only_event calls

Fixes trace_id inconsistency found in MESSAGE_RUN, TOOL_EXECUTION,
MODERATION_CHECK, SUGGESTED_QUESTION_GENERATION, GENERATE_NAME_EXECUTION,
DATASET_RETRIEVAL, and PROMPT_GENERATION_EXECUTION events.

All 78 telemetry tests passing.

api/core/ops/entities/trace_entity.py

@@ -27,6 +27,26 @@ class BaseTraceInfo(BaseModel):
 
     model_config = ConfigDict(protected_namespaces=())
 
+    @property
+    def resolved_trace_id(self) -> str | None:
+        """Get trace_id with intelligent fallback.
+        
+        Priority:
+        1. External trace_id (from X-Trace-Id header)
+        2. workflow_run_id (if this trace type has it)
+        3. message_id (as final fallback)
+        """
+        if self.trace_id:
+            return self.trace_id
+        
+        # Try workflow_run_id (only exists on workflow-related traces)
+        workflow_run_id = getattr(self, "workflow_run_id", None)
+        if workflow_run_id:
+            return workflow_run_id
+        
+        # Final fallback to message_id
+        return str(self.message_id) if self.message_id else None
+
     @field_serializer("start_time", "end_time")
     def serialize_datetime(self, dt: datetime | None) -> str | None:
         if dt is None:

api/enterprise/telemetry/enterprise_trace.py

@@ -102,7 +102,7 @@ class EnterpriseOtelTrace:
         metadata = self._metadata(trace_info)
         tenant_id, app_id, user_id = self._context_ids(trace_info, metadata)
         return {
-            "dify.trace_id": trace_info.trace_id,
+            "dify.trace_id": trace_info.resolved_trace_id,
             "dify.tenant_id": tenant_id,
             "dify.app_id": app_id,
             "dify.app.name": metadata.get("app_name"),
@@ -163,7 +163,7 @@ class EnterpriseOtelTrace:
         tenant_id, app_id, user_id = self._context_ids(info, metadata)
         # -- Slim span attrs: identity + structure + status + timing only --
         span_attrs: dict[str, Any] = {
-            "dify.trace_id": info.trace_id,
+            "dify.trace_id": info.resolved_trace_id,
             "dify.tenant_id": tenant_id,
             "dify.app_id": app_id,
             "dify.workflow.id": info.workflow_id,
@@ -307,7 +307,7 @@ class EnterpriseOtelTrace:
         tenant_id, app_id, user_id = self._context_ids(info, metadata)
         # -- Slim span attrs: identity + structure + status + timing --
         span_attrs: dict[str, Any] = {
-            "dify.trace_id": info.trace_id,
+            "dify.trace_id": info.resolved_trace_id,
             "dify.tenant_id": tenant_id,
             "dify.app_id": app_id,
             "dify.workflow.id": info.workflow_id,
@@ -563,6 +563,7 @@ class EnterpriseOtelTrace:
         emit_metric_only_event(
             event_name=EnterpriseTelemetryEvent.TOOL_EXECUTION,
             attributes=attrs,
+            trace_id_source=info.resolved_trace_id,
             span_id_source=node_execution_id,
             tenant_id=tenant_id,
             user_id=user_id,
@@ -617,6 +618,7 @@ class EnterpriseOtelTrace:
         emit_metric_only_event(
             event_name=EnterpriseTelemetryEvent.MODERATION_CHECK,
             attributes=attrs,
+            trace_id_source=info.resolved_trace_id,
             span_id_source=node_execution_id,
             tenant_id=tenant_id,
             user_id=user_id,
@@ -662,6 +664,7 @@ class EnterpriseOtelTrace:
         emit_metric_only_event(
             event_name=EnterpriseTelemetryEvent.SUGGESTED_QUESTION_GENERATION,
             attributes=attrs,
+            trace_id_source=info.resolved_trace_id,
             span_id_source=node_execution_id,
             tenant_id=tenant_id,
             user_id=user_id,
@@ -818,6 +821,7 @@ class EnterpriseOtelTrace:
         emit_metric_only_event(
             event_name=EnterpriseTelemetryEvent.GENERATE_NAME_EXECUTION,
             attributes=attrs,
+            trace_id_source=info.resolved_trace_id,
             span_id_source=node_execution_id,
             tenant_id=tenant_id,
             user_id=user_id,
@@ -840,7 +844,7 @@ class EnterpriseOtelTrace:
         metadata = self._metadata(info)
         tenant_id, app_id, user_id = self._context_ids(info, metadata)
         attrs = {
-            "dify.trace_id": info.trace_id,
+            "dify.trace_id": info.resolved_trace_id,
             "dify.tenant_id": tenant_id,
             "dify.user.id": user_id,
             "dify.app.id": app_id or "",
@@ -871,6 +875,7 @@ class EnterpriseOtelTrace:
         emit_metric_only_event(
             event_name=EnterpriseTelemetryEvent.PROMPT_GENERATION_EXECUTION,
             attributes=attrs,
+            trace_id_source=info.resolved_trace_id,
             span_id_source=node_execution_id,
             tenant_id=tenant_id,
             user_id=user_id,