docs: add attribute propagation guidance to OpenTelemetry integration

[Steffen911]

Summary

Extends the OpenTelemetry integration documentation to include comprehensive guidance on attribute propagation for trace-level attributes. This documentation builds on the work from #2240 where similar guidance was added to the Python and JS SDK docs.

Changes

Added a new subsection "Propagating Trace Attributes to All Spans" within the Property Mapping section (pages/integrations/native/opentelemetry.mdx) that covers:

• Why propagation is needed: Explains that userId, sessionId, metadata, version, release, and tags should be propagated to all spans for accurate filtering and aggregations in future Langfuse versions
• Recommended approach: Details using OpenTelemetry Baggage with BaggageSpanProcessor as the primary method for users not using Langfuse SDKs
• Security considerations: Prominent warning about baggage propagating to third-party services and avoiding sensitive data
• Alternative option: References Langfuse SDK v3's propagate_attributes() methods for users of the SDK
• Future compatibility: Positions as "strongly recommended now" without specifying hard transition date

Context

This addresses the need to communicate the upcoming change where Langfuse aggregations will operate on individual observations rather than just trace-level data. The OpenTelemetry integration doc is specifically for users who are not using the Langfuse SDKs directly, so the focus is on native OpenTelemetry patterns (baggage) rather than SDK-specific methods.

Related

• docs: add trace attribute propagation #2240 - PR that added similar propagation guidance to Python and JS SDK docs

🤖 Generated with Claude Code

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Important

Adds guidance on propagating trace-level attributes to all spans in OpenTelemetry integration docs for future Langfuse compatibility.

• Documentation Update:
  • Adds "Propagating Trace Attributes to All Spans" subsection in opentelemetry.mdx.
  • Explains the need for propagating userId, sessionId, metadata, version, release, and tags to all spans for future Langfuse compatibility.
  • Recommends using OpenTelemetry Baggage with BaggageSpanProcessor for propagation.
  • Warns against including sensitive data in baggage due to third-party propagation.
  • Mentions Langfuse SDK v3's propagate_attributes() as an alternative for SDK users.

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Project	Deployment	Preview	Updated (UTC)
langfuse-docs	Ready	Preview	Nov 11, 2025 8:57am

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One Page Changed Size

The following page changed size from the code in this PR compared to its base branch:

Page	Size (compressed)	First Load	% of Budget (350 KB)
/integrations/native/opentelemetry	62.67 KB	459.02 KB	131.15% (🟡 +0.29%)

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