Trace context on /api/public/v2/observations
Niklas Semmler, PhDFetch a trace's tags, release, and trace name directly on each observation row
/api/public/v2/observations is significantly faster than the v1 endpoint at scale — it uses cursor-based pagination and selective field retrieval so you only pay for the columns you actually need. See the Langfuse v4 data model for the full picture of what changed.
The API /api/public/v2/observations now supports the trace_context field group. Add it to your fields query parameter and each observation comes back with tags, release, and traceName — denormalized from the parent trace, no extra /traces/{id} calls needed.
GET /api/public/v2/observations?fields=core,basic,trace_contextCommon cases this simplifies:
- Filter observations by trace tag in a downstream pipeline without keeping a trace lookup table.
- Group observations by release for regression analysis directly on the observations response.
- Render trace names in an analytics view that paginates observations.
trace_context joins the existing groups (core, basic, time, io, metadata, model, usage, prompt, metrics) on the v2 endpoint. The full table is in the Observations API v2 docs.
usagePricingTierName also moved from trace_context to the usage group on the same endpoint — it's an observation-level pricing attribute, not parent-trace metadata.