feat(telemetry/utils): add ttft reporting to LangFuse #3594
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bml1g12
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longcw
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Oct 8, 2025
| # Langfuse only allows searching/filtering/graphing over fields if they are prefixes with this key OR | ||
| # which use a set of reserved keys like ATTR_GEN_AI and ATTR_LANGFUSE items above. | ||
| # so e.g. ATTR_LANGFUSE_SEARCHABLE_PREFIX + "foo" will allow `foo` to be a filterable attribute in langfuse. | ||
| ATTR_LANGFUSE_SEARCHABLE_PREFIX = "langfuse.trace.metadata." |
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is this used anywhere? if not it's better to not include it in the types.
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you don't think its useful reference for devs (i.e. to sign post you cannot assume simply adding an atrribute makes it useful for searching/graphing in langfuse)? This information was a little hard for me to find as a developer and surprising behaviour in LangFuse (that metadata attached to a trace is not searchable unless nested under very specific namespaces).
But OK I have removed it now
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I think it's langfuse should document this somewhere, we may not want to add too many platform-specific vars in the codebase.
longcw
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Oct 8, 2025
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* staging: (114 commits) Added min_confidence_threshold for deepgram flux. livekit-agents 1.2.15 (livekit#3658) fix livekit#3650 cartesia version backward compatibility (livekit#3651) Unprompted STT Reconnection at startup (livekit#3649) enable zero retention mode in elevenlabs (livekit#3647) fix: heartbeat (livekit#3648) feat: Integrate streaming endpoints for Sarvam APIs (livekit#3498) turn_detection: reduce max_endpointing_delay to 3s (livekit#3640) fix: exclude temperature parameter for gpt-5 and similar models (livekit#3573) add backwards compatibility for google's realtime model (livekit#3630) Align Google STT plugin with official documentation (livekit#3628) feat(speechmatics): add max_speakers parameter for speaker diarization (livekit#3524) fix(deepgram): send CloseStream message before closing TTS WebSocket (livekit#3608) chore: Remove duplicate docstring for `preemptive_generation` parameter in AgentSession (livekit#3624) Add RTZR(ReturnZero) STT Plugin for LiveKit Agents (livekit#3376) feat(telemetry/utils): add ttft reporting to LangFuse (livekit#3594) catch delete_room errors and disable delete_room_on_close by default (livekit#3600) lift google realtime api out of beta (livekit#3614) fix: lock pyav to <16 due to build issue (livekit#3593) Updating Cartesia Version (livekit#3570) ...
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This PR extends the recent addition of TTFT metrics to Realtime API kindly provided by @longcw #3507 to allow LangFuse to natively parse this data, as currently it is not possible to Dashboard or filter on TTFT.
This PR makes two changes:
ATTR_LANGFUSE_COMPLETION_START_TIME = "langfuse.observation.completion_start_time"namespace, similarly to how in the codebase we already do for regular non-realtime LLMs.