feat: [SVLS-8720] Add span tag aws_lambda.durable_function.first_invocation (#747)

* Add durable_function_first_invocation tag to aws.lambda spans

Extends extract_durable_function_tags() to accept context.state and
sets durable_function_first_invocation ("true"/"false") using
not state.is_replaying(). wrapper._before() passes context.state
to the function.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Add durable_function_first_invocation tag to aws.lambda spans

Extends extract_durable_function_tags() to set
durable_function_first_invocation ("true"/"false") by checking
len(InitialExecutionState.Operations) <= 1, mirroring the SDK's
own replay detection logic (ReplayStatus.REPLAY when len > 1).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* Add comment

* Change <= 1 to == 1

* Update comments

* fmt

* feat: [SVLS-8493] use aws_lambda prefix for durable function tags

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: lym953

datadog_lambda/durable.py

@@ -41,11 +41,17 @@ def extract_durable_function_tags(event):
     if not parsed:
         logger.error("Failed to parse DurableExecutionArn: %s", durable_execution_arn)
         return {}
-
     execution_name, execution_id = parsed
+    # Use the number of operations to determine if it's the first invocation. This is
+    # what the durable execution SDK does to determine the replay status.
+    operations = event.get("InitialExecutionState", {}).get("Operations", [])
+    is_first_invocation = len(operations) == 1
     return {
         "aws_lambda.durable_function.execution_name": execution_name,
         "aws_lambda.durable_function.execution_id": execution_id,
+        "aws_lambda.durable_function.first_invocation": str(
+            is_first_invocation
+        ).lower(),
     }
 
 

tests/test_durable.py

@@ -46,18 +46,42 @@ def test_works_with_numeric_version_qualifier(self):
 
 
 class TestExtractDurableFunctionTags(unittest.TestCase):
-    def test_extracts_tags_from_event_with_durable_execution_arn(self):
+    def test_sets_first_invocation_true_when_only_execution_operation(self):
+        # One operation (the current EXECUTION operation itself) → not replaying → first invocation
         event = {
             "DurableExecutionArn": "arn:aws:lambda:us-east-1:123456789012:function:my-func:1/durable-execution/my-execution/550e8400-e29b-41d4-a716-446655440004",
             "CheckpointToken": "some-token",
-            "InitialExecutionState": {"Operations": []},
+            "InitialExecutionState": {"Operations": [{"OperationType": "EXECUTION"}]},
         }
         result = extract_durable_function_tags(event)
         self.assertEqual(
             result,
             {
                 "aws_lambda.durable_function.execution_name": "my-execution",
                 "aws_lambda.durable_function.execution_id": "550e8400-e29b-41d4-a716-446655440004",
+                "aws_lambda.durable_function.first_invocation": "true",
+            },
+        )
+
+    def test_sets_first_invocation_false_when_multiple_operations(self):
+        # More than one operation → replaying → not first invocation
+        event = {
+            "DurableExecutionArn": "arn:aws:lambda:us-east-1:123456789012:function:my-func:1/durable-execution/my-execution/550e8400-e29b-41d4-a716-446655440004",
+            "CheckpointToken": "some-token",
+            "InitialExecutionState": {
+                "Operations": [
+                    {"OperationType": "EXECUTION"},
+                    {"OperationType": "STEP"},
+                ]
+            },
+        }
+        result = extract_durable_function_tags(event)
+        self.assertEqual(
+            result,
+            {
+                "aws_lambda.durable_function.execution_name": "my-execution",
+                "aws_lambda.durable_function.execution_id": "550e8400-e29b-41d4-a716-446655440004",
+                "aws_lambda.durable_function.first_invocation": "false",
             },
         )