feat: [SVLS-8493] add first_invocation tag for durable functions

Tag `aws_lambda.durable_function.first_invocation` is set to "true"
when `InitialExecutionState.Operations` has exactly one entry (first
invocation) and "false" when it has more (replay). Omitted when
InitialExecutionState is absent.

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

Author: lym953

src/trace/durable-function-context.spec.ts

@@ -58,9 +58,47 @@ describe("durable-function-context", () => {
       expect(result).toEqual({
         "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",
       });
     });
 
+    it("sets first_invocation to true when Operations has exactly one entry", () => {
+      const event = {
+        DurableExecutionArn:
+          "arn:aws:lambda:us-east-1:123456789012:function:my-func:1/durable-execution/my-execution/550e8400-e29b-41d4-a716-446655440004",
+        InitialExecutionState: {
+          Operations: [{ type: "TaskScheduled" }],
+        },
+      };
+      const result = extractDurableFunctionContext(event);
+
+      expect(result?.["aws_lambda.durable_function.first_invocation"]).toBe("true");
+    });
+
+    it("sets first_invocation to false when Operations has more than one entry", () => {
+      const event = {
+        DurableExecutionArn:
+          "arn:aws:lambda:us-east-1:123456789012:function:my-func:1/durable-execution/my-execution/550e8400-e29b-41d4-a716-446655440004",
+        InitialExecutionState: {
+          Operations: [{ type: "TaskScheduled" }, { type: "TaskCompleted" }],
+        },
+      };
+      const result = extractDurableFunctionContext(event);
+
+      expect(result?.["aws_lambda.durable_function.first_invocation"]).toBe("false");
+    });
+
+    it("omits first_invocation when InitialExecutionState is absent", () => {
+      const event = {
+        DurableExecutionArn:
+          "arn:aws:lambda:us-east-1:123456789012:function:my-func:1/durable-execution/my-execution/550e8400-e29b-41d4-a716-446655440004",
+      };
+      const result = extractDurableFunctionContext(event);
+
+      expect(result).toBeDefined();
+      expect(result?.["aws_lambda.durable_function.first_invocation"]).toBeUndefined();
+    });
+
     it("returns undefined for regular Lambda event without DurableExecutionArn", () => {
       const event = {
         body: '{"key": "value"}',

src/trace/durable-function-context.ts

@@ -3,6 +3,7 @@ import { logDebug } from "../utils";
 export interface DurableFunctionContext {
   "aws_lambda.durable_function.execution_name": string;
   "aws_lambda.durable_function.execution_id": string;
+  "aws_lambda.durable_function.first_invocation"?: string;
 }
 
 export function extractDurableFunctionContext(event: any): DurableFunctionContext | undefined {
@@ -18,10 +19,18 @@ export function extractDurableFunctionContext(event: any): DurableFunctionContex
     return undefined;
   }
 
-  return {
+  const context: DurableFunctionContext = {
     "aws_lambda.durable_function.execution_name": parsed.executionName,
     "aws_lambda.durable_function.execution_id": parsed.executionId,
   };
+
+  // Use the number of operations to determine if it's the first invocation.
+  const operations = event?.InitialExecutionState?.Operations;
+  if (Array.isArray(operations)) {
+    context["aws_lambda.durable_function.first_invocation"] = String(operations.length === 1);
+  }
+
+  return context;
 }
 
 /**