Add $ai_lib_metadata to AI integrations

Adds framework identification metadata to all AI events for easier filtering
and analytics. Each integration now includes a $ai_lib_metadata property with
schema version and framework name.

- LangChain: Hardcoded to "langchain"
- Native wrappers (Anthropic, OpenAI, Gemini): Uses provider name
- Ready for future frameworks (pydantic-ai, crewai, llamaindex)

This enables PostHog queries to easily distinguish between:
- Direct SDK wrapper usage
- Framework-mediated usage (LangChain, etc.)
- Different framework types

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: andrewm4894

posthog/ai/langchain/callbacks.py

@@ -486,6 +486,7 @@ def _capture_trace_or_span(
             "$ai_latency": run.latency,
             "$ai_span_name": run.name,
             "$ai_span_id": run_id,
+            "$ai_lib_metadata": _get_ai_lib_metadata(),
         }
         if parent_run_id is not None:
             event_properties["$ai_parent_id"] = parent_run_id
@@ -556,6 +557,7 @@ def _capture_generation(
             "$ai_http_status": 200,
             "$ai_latency": run.latency,
             "$ai_base_url": run.base_url,
+            "$ai_lib_metadata": _get_ai_lib_metadata(),
         }
 
         if run.tools:
@@ -865,3 +867,12 @@ def _stringify_exception(exception: BaseException) -> str:
     if description:
         return f"{exception.__class__.__name__}: {description}"
     return exception.__class__.__name__
+
+
+def _get_ai_lib_metadata() -> Dict[str, Any]:
+    """
+    Generate the $ai_lib_metadata dict with framework information.
+    Since this file is langchain/callbacks.py, we know the framework is LangChain.
+    Returns a dict with schema version and framework name.
+    """
+    return {"schema": "v1", "frameworks": [{"name": "langchain"}]}

posthog/ai/utils.py

@@ -483,6 +483,7 @@ def capture_streaming_event(
 
     # Build base event properties
     event_properties = {
+        "$ai_lib_metadata": {"schema": "v1", "frameworks": [{"name": event_data["provider"]}]},
         "$ai_provider": event_data["provider"],
         "$ai_model": event_data["model"],
         "$ai_model_parameters": get_model_params(event_data["kwargs"]),