Fix parent_id to set on span context instead of span attribute

Changed the parent_id implementation to properly link spans by parsing the
W3C Trace Context format parent ID and using it to create a proper span
context. This aligns with the .NET implementation which calls
`activity?.SetParentId(parentId!)`.

Added validation for W3C Trace Context version and trace_id/span_id lengths.

Co-authored-by: nikhilNava <211831449+nikhilNava@users.noreply.github.com>

Author: Copilot

libraries/microsoft-agents-a365-observability-core/microsoft_agents_a365/observability/core/opentelemetry_scope.py

@@ -10,10 +10,19 @@
 from typing import TYPE_CHECKING, Any
 
 from opentelemetry import baggage, context, trace
-from opentelemetry.trace import Span, SpanKind, Status, StatusCode, Tracer, set_span_in_context
+from opentelemetry.trace import (
+    NonRecordingSpan,
+    Span,
+    SpanContext,
+    SpanKind,
+    Status,
+    StatusCode,
+    TraceFlags,
+    Tracer,
+    set_span_in_context,
+)
 
 from .constants import (
-    CUSTOM_PARENT_SPAN_ID_KEY,
     ENABLE_A365_OBSERVABILITY,
     ENABLE_OBSERVABILITY,
     ERROR_TYPE_KEY,
@@ -42,6 +51,70 @@
 logger = logging.getLogger(__name__)
 
 
+def _parse_parent_id_to_context(parent_id: str | None) -> context.Context | None:
+    """Parse a W3C trace context parent ID and return a context with the parent span.
+
+    The parent_id format is expected to be W3C Trace Context format:
+    "00-{trace_id}-{span_id}-{trace_flags}"
+    Example: "00-1234567890abcdef1234567890abcdef-abcdefabcdef1234-01"
+
+    Args:
+        parent_id: The W3C Trace Context format parent ID string
+
+    Returns:
+        A context containing the parent span, or None if parent_id is invalid
+    """
+    if not parent_id:
+        return None
+
+    try:
+        # W3C Trace Context format: "00-{trace_id}-{span_id}-{trace_flags}"
+        parts = parent_id.split("-")
+        if len(parts) != 4:
+            logger.warning(f"Invalid parent_id format (expected 4 parts): {parent_id}")
+            return None
+
+        version, trace_id_hex, span_id_hex, trace_flags_hex = parts
+
+        # Validate W3C Trace Context version
+        if version != "00":
+            logger.warning(f"Unsupported W3C Trace Context version: {version}")
+            return None
+
+        # Validate trace_id length (must be 32 hex chars)
+        if len(trace_id_hex) != 32:
+            logger.warning(f"Invalid trace_id length (expected 32 chars): {len(trace_id_hex)}")
+            return None
+
+        # Validate span_id length (must be 16 hex chars)
+        if len(span_id_hex) != 16:
+            logger.warning(f"Invalid span_id length (expected 16 chars): {len(span_id_hex)}")
+            return None
+
+        # Parse the hex values
+        trace_id = int(trace_id_hex, 16)
+        span_id = int(span_id_hex, 16)
+        trace_flags = TraceFlags(int(trace_flags_hex, 16))
+
+        # Create a SpanContext from the parsed values
+        parent_span_context = SpanContext(
+            trace_id=trace_id,
+            span_id=span_id,
+            is_remote=True,
+            trace_flags=trace_flags,
+        )
+
+        # Create a NonRecordingSpan with the parent context
+        parent_span = NonRecordingSpan(parent_span_context)
+
+        # Create a context with the parent span
+        return set_span_in_context(parent_span)
+
+    except (ValueError, IndexError) as e:
+        logger.warning(f"Failed to parse parent_id '{parent_id}': {e}")
+        return None
+
+
 class OpenTelemetryScope:
     """Base class for OpenTelemetry tracing scopes in the SDK."""
 
@@ -106,12 +179,13 @@ def __init__(
             elif kind.lower() == "consumer":
                 activity_kind = SpanKind.CONSUMER
 
-            # Get current context for parent relationship
-            current_context = context.get_current()
+            # Get context for parent relationship
+            # If parent_id is provided, parse it and use it as the parent context
+            # Otherwise, use the current context
+            parent_context = _parse_parent_id_to_context(parent_id)
+            span_context = parent_context if parent_context else context.get_current()
 
-            self._span = tracer.start_span(
-                activity_name, kind=activity_kind, context=current_context
-            )
+            self._span = tracer.start_span(activity_name, kind=activity_kind, context=span_context)
 
             # Log span creation
             if self._span:
@@ -149,9 +223,6 @@ def __init__(
                 if tenant_details:
                     self.set_tag_maybe(TENANT_ID_KEY, str(tenant_details.tenant_id))
 
-                # Set parent ID if provided
-                self.set_tag_maybe(CUSTOM_PARENT_SPAN_ID_KEY, parent_id)
-
     def record_error(self, exception: Exception) -> None:
         """Record an error in the span.
 

tests/observability/core/test_output_scope.py

@@ -14,10 +14,7 @@
     get_tracer_provider,
 )
 from microsoft_agents_a365.observability.core.config import _telemetry_manager
-from microsoft_agents_a365.observability.core.constants import (
-    CUSTOM_PARENT_SPAN_ID_KEY,
-    GEN_AI_OUTPUT_MESSAGES_KEY,
-)
+from microsoft_agents_a365.observability.core.constants import GEN_AI_OUTPUT_MESSAGES_KEY
 from microsoft_agents_a365.observability.core.models.response import Response
 from microsoft_agents_a365.observability.core.opentelemetry_scope import OpenTelemetryScope
 from microsoft_agents_a365.observability.core.spans_scopes.output_scope import OutputScope
@@ -223,9 +220,13 @@ def test_output_scope_span_name(self):
         self.assertIn(self.agent_details.agent_id, span.name)
 
     def test_output_scope_with_parent_id(self):
-        """Test that OutputScope records parent_id when provided."""
+        """Test that OutputScope uses parent_id to link span to parent."""
         response = Response(messages=["Test message with parent"])
-        parent_id = "00-1234567890abcdef1234567890abcdef-abcdefabcdef1234-01"
+        # W3C Trace Context format: "00-{trace_id}-{span_id}-{trace_flags}"
+        # trace_id: 32 hex chars, span_id: 16 hex chars
+        parent_trace_id = "1234567890abcdef1234567890abcdef"
+        parent_span_id = "abcdefabcdef1234"
+        parent_id = f"00-{parent_trace_id}-{parent_span_id}-01"
 
         scope = OutputScope.start(
             self.agent_details, self.tenant_details, response, parent_id=parent_id
@@ -238,18 +239,28 @@ def test_output_scope_with_parent_id(self):
         self.assertTrue(finished_spans, "Expected at least one span to be created")
 
         span = finished_spans[-1]
-        span_attributes = getattr(span, "attributes", {}) or {}
 
-        # Verify the parent ID is set as a span attribute
-        self.assertIn(
-            CUSTOM_PARENT_SPAN_ID_KEY,
-            span_attributes,
-            "Expected custom parent span ID to be set on span",
+        # Verify the span has the correct parent trace context
+        # The span's trace_id should match the parent's trace_id
+        span_trace_id = f"{span.context.trace_id:032x}"
+        self.assertEqual(
+            span_trace_id,
+            parent_trace_id,
+            "Expected span's trace_id to match parent's trace_id",
+        )
+
+        # The span's parent_span_id should match the parent's span_id
+        span_parent_id = None
+        if span.parent and hasattr(span.parent, "span_id"):
+            span_parent_id = f"{span.parent.span_id:016x}"
+        self.assertEqual(
+            span_parent_id,
+            parent_span_id,
+            "Expected span's parent_span_id to match parent's span_id",
         )
-        self.assertEqual(span_attributes[CUSTOM_PARENT_SPAN_ID_KEY], parent_id)
 
     def test_output_scope_without_parent_id(self):
-        """Test that OutputScope doesn't set parent_id attribute when not provided."""
+        """Test that OutputScope creates a span without forced parent when not provided."""
         response = Response(messages=["Test message without parent"])
 
         scope = OutputScope.start(self.agent_details, self.tenant_details, response)
@@ -261,14 +272,11 @@ def test_output_scope_without_parent_id(self):
         self.assertTrue(finished_spans, "Expected at least one span to be created")
 
         span = finished_spans[-1]
-        span_attributes = getattr(span, "attributes", {}) or {}
 
-        # Verify the parent ID attribute is NOT set when not provided
-        self.assertNotIn(
-            CUSTOM_PARENT_SPAN_ID_KEY,
-            span_attributes,
-            "Expected custom parent span ID NOT to be set when not provided",
-        )
+        # When no parent_id is provided, the span should either have no parent
+        # or inherit from the current context (which in tests is typically empty)
+        # We just verify the span was created successfully
+        self.assertIsNotNone(span.context.span_id)
 
 
 if __name__ == "__main__":