fix: update OCS langfuse integration for v4 SDK#3218
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Breaking changes in langfuse 3→4:
- FernLangfuse renamed to LangfuseAPI
- start_as_current_span() → start_as_current_observation()
- update_trace() removed; use propagate_attributes() context manager instead
(must wrap the outer observation to set session_id/user_id on root span)
- span.update(tags=...) no longer supported; use
_create_trace_tags_via_ingestion() for trace-level tags
- langfuse.api.resources.{commons,ingestion}.types namespace dropped;
now langfuse.api.{commons,ingestion}.types
Closes #3129
![sentry[bot]](https://avatars.githubusercontent.com/in/12637?s=60&v=4){kind=small}
SmittieC
approved these changes
Apr 23, 2026
SmittieC
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Tested this locally and it seems to work fine
Contributor
Really? I was just testing and wasn't getting any langfuse trace links in the session |
Contributor
oh you know what, I didn't actually run |
Contributor
I'm digging into it so no need to persue |
In v4, client.get_trace_url() makes a blocking HTTP call to fetch the project_id. If that raises, TracingService's broad except used to drop the entire langfuse entry from trace_info, so ChatMessage.metadata ended up with no langfuse trace data. Isolate the URL fetch so trace_id still lands in metadata regardless. Capture the langfuse trace id via client.get_current_trace_id() on context entry and reuse it for get_trace_metadata() and add_trace_tags(). Add regression tests that exercise the TracingService -> LangFuseTracer path with a realistic mock client, including the URL-fetch failure case. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
snopoke
approved these changes
Apr 24, 2026
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Fixes the breaking changes introduced by the langfuse 3→4 SDK upgrade (#3129). Needs to be merged into that branch before #3129 is merged to main.
Breaking changes addressed
apps/service_providers/tracing/langfuse.pyFernLangfuseLangfuseAPIclient.start_as_current_span(...)client.start_as_current_observation(...)trace.update_trace(session_id=..., user_id=...)propagate_attributes(session_id=..., user_id=...)wrapping the observation (must be outer context so attrs land on root span)span.update(tags=tags)client._create_trace_tags_via_ingestion(trace_id=..., tags=tags)apps/service_providers/management/commands/migrate_langfuse_data.pylangfuse.api.resources.commons.typeslangfuse.api.commons.typeslangfuse.api.resources.ingestion.typeslangfuse.api.ingestion.typesWhat was NOT broken
LangfuseResourceManagerprivate API (_lock,_instances,reset()) — still intact in v4 ✅_create_client_from_instance— still intact ✅span.trace_id,client.get_trace_url()— still intact ✅langfuse.api.core.api_error.ApiError— still intact ✅IngestionEvent_*types — still inlangfuse.api.ingestion.types✅LangfuseCallbackHandler._get_parent_observation()— still intact ✅