test(e2e): Add e2e assertions for messages.batches API instrumentation

Adds scenario coverage and snapshot assertions for the Anthropic Message
Batches API (create, retrieve, list, cancel) across all supported SDK
versions (v0.39.0+). Normalizes volatile batch response fields
(timestamps, batch IDs, list bodies) for stable snapshots.

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

Author: Qard

e2e/scenarios/anthropic-instrumentation/__snapshots__/anthropic-v0390.log-payloads.json

@@ -302,6 +302,149 @@
     },
     "type": "llm"
   },
+  {
+    "metadata": {
+      "operation": "batches"
+    },
+    "metrics": {
+      "end": 0,
+      "start": 0
+    },
+    "name": "anthropic-batches-operation",
+    "type": null
+  },
+  {
+    "input": [
+      {
+        "custom_id": "braintrust-e2e-test",
+        "params": {
+          "max_tokens": 16,
+          "messages": [
+            {
+              "content": "Reply with exactly OK.",
+              "role": "user"
+            }
+          ],
+          "model": "claude-3-haiku-20240307"
+        }
+      }
+    ],
+    "metadata": {
+      "provider": "anthropic"
+    },
+    "metrics": {
+      "end": 0,
+      "start": 0
+    },
+    "name": "anthropic.messages.batches.create",
+    "output": {
+      "archived_at": null,
+      "cancel_initiated_at": null,
+      "created_at": "<timestamp>",
+      "ended_at": null,
+      "expires_at": "<timestamp>",
+      "id": "<span:3>",
+      "processing_status": "<processing_status>",
+      "request_counts": {
+        "canceled": 0,
+        "errored": 0,
+        "expired": 0,
+        "processing": 0,
+        "succeeded": 0
+      },
+      "results_url": null,
+      "type": "message_batch"
+    },
+    "type": "llm"
+  },
+  {
+    "input": "<msgbatch_id>",
+    "metadata": {
+      "provider": "anthropic"
+    },
+    "metrics": {
+      "end": 0,
+      "start": 0
+    },
+    "name": "anthropic.messages.batches.retrieve",
+    "output": {
+      "archived_at": null,
+      "cancel_initiated_at": null,
+      "created_at": "<timestamp>",
+      "ended_at": null,
+      "expires_at": "<timestamp>",
+      "id": "<span:3>",
+      "processing_status": "<processing_status>",
+      "request_counts": {
+        "canceled": 0,
+        "errored": 0,
+        "expired": 0,
+        "processing": 0,
+        "succeeded": 0
+      },
+      "results_url": null,
+      "type": "message_batch"
+    },
+    "type": "llm"
+  },
+  {
+    "input": null,
+    "metadata": {
+      "provider": "anthropic"
+    },
+    "metrics": {
+      "end": 0,
+      "start": 0
+    },
+    "name": "anthropic.messages.batches.list",
+    "output": {
+      "body": "<batch-list-body>",
+      "data": "<batch-list-data>",
+      "first_id": "<msgbatch_id>",
+      "has_more": true,
+      "last_id": "<msgbatch_id>",
+      "options": {
+        "method": "get",
+        "path": "/v1/messages/batches",
+        "query": {}
+      },
+      "response": {
+        "size": 0,
+        "timeout": 0
+      }
+    },
+    "type": "llm"
+  },
+  {
+    "input": "<msgbatch_id>",
+    "metadata": {
+      "provider": "anthropic"
+    },
+    "metrics": {
+      "end": 0,
+      "start": 0
+    },
+    "name": "anthropic.messages.batches.cancel",
+    "output": {
+      "archived_at": null,
+      "cancel_initiated_at": "<timestamp>",
+      "created_at": "<timestamp>",
+      "ended_at": null,
+      "expires_at": "<timestamp>",
+      "id": "<span:3>",
+      "processing_status": "<processing_status>",
+      "request_counts": {
+        "canceled": 0,
+        "errored": 0,
+        "expired": 0,
+        "processing": 0,
+        "succeeded": 0
+      },
+      "results_url": null,
+      "type": "message_batch"
+    },
+    "type": "llm"
+  },
   {
     "metadata": {
       "operation": "beta-create"

e2e/scenarios/anthropic-instrumentation/__snapshots__/anthropic-v0390.span-events.json

@@ -240,6 +240,81 @@
     ],
     "type": "llm"
   },
+  {
+    "has_input": false,
+    "has_output": false,
+    "metadata": {
+      "operation": "batches"
+    },
+    "metric_keys": [],
+    "name": "anthropic-batches-operation",
+    "root_span_id": "<span:1>",
+    "span_id": "<span:14>",
+    "span_parents": [
+      "<span:1>"
+    ],
+    "type": null
+  },
+  {
+    "has_input": true,
+    "has_output": true,
+    "metadata": {
+      "provider": "anthropic"
+    },
+    "metric_keys": [],
+    "name": "anthropic.messages.batches.create",
+    "root_span_id": "<span:1>",
+    "span_id": "<span:15>",
+    "span_parents": [
+      "<span:14>"
+    ],
+    "type": "llm"
+  },
+  {
+    "has_input": true,
+    "has_output": true,
+    "metadata": {
+      "provider": "anthropic"
+    },
+    "metric_keys": [],
+    "name": "anthropic.messages.batches.retrieve",
+    "root_span_id": "<span:1>",
+    "span_id": "<span:16>",
+    "span_parents": [
+      "<span:14>"
+    ],
+    "type": "llm"
+  },
+  {
+    "has_input": false,
+    "has_output": true,
+    "metadata": {
+      "provider": "anthropic"
+    },
+    "metric_keys": [],
+    "name": "anthropic.messages.batches.list",
+    "root_span_id": "<span:1>",
+    "span_id": "<span:17>",
+    "span_parents": [
+      "<span:14>"
+    ],
+    "type": "llm"
+  },
+  {
+    "has_input": true,
+    "has_output": true,
+    "metadata": {
+      "provider": "anthropic"
+    },
+    "metric_keys": [],
+    "name": "anthropic.messages.batches.cancel",
+    "root_span_id": "<span:1>",
+    "span_id": "<span:18>",
+    "span_parents": [
+      "<span:14>"
+    ],
+    "type": "llm"
+  },
   {
     "has_input": false,
     "has_output": false,
@@ -249,7 +324,7 @@
     "metric_keys": [],
     "name": "anthropic-beta-create-operation",
     "root_span_id": "<span:1>",
-    "span_id": "<span:14>",
+    "span_id": "<span:19>",
     "span_parents": [
       "<span:1>"
     ],
@@ -272,9 +347,9 @@
     ],
     "name": "anthropic.messages.create",
     "root_span_id": "<span:1>",
-    "span_id": "<span:15>",
+    "span_id": "<span:20>",
     "span_parents": [
-      "<span:14>"
+      "<span:19>"
     ],
     "type": "llm"
   },
@@ -287,7 +362,7 @@
     "metric_keys": [],
     "name": "anthropic-beta-stream-operation",
     "root_span_id": "<span:1>",
-    "span_id": "<span:16>",
+    "span_id": "<span:21>",
     "span_parents": [
       "<span:1>"
     ],
@@ -310,9 +385,9 @@
     ],
     "name": "anthropic.messages.create",
     "root_span_id": "<span:1>",
-    "span_id": "<span:17>",
+    "span_id": "<span:22>",
     "span_parents": [
-      "<span:16>"
+      "<span:21>"
     ],
     "type": "llm"
   }