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eve provider: `capture` key crashes eve ≥0.62 at boot, and `eve.turn` spans have no input/output

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Assessment

Difficulty
3/5
Estimated time
1-2 days
Newbie friendliness
72/100
Issue type
Bug
Clarity
Clearly specified
Activity status
Active
Tech stack
typescript
Domain
observability

Research direction

Start in js/src/instrumentation/plugins/eve-provider.ts at createEveInstrumentationProvider and inspect the handleTurnStarted and handleTurnTerminal paths. Reproduce with the listed eve init/add/build flow, then verify the provider boots without the rejected key and that eve.turn records the user message as input and final assistant reply as output.

Written by the indexing model from the issue text.

Description

Versions: braintrust 3.35.0 (latest), eve 0.69.0, Node 24, deployed on Vercel. Installed via eve add instrumentation/braintrust.

1. eve refuses to start with the provider

createEveInstrumentationProvider (js/src/instrumentation/plugins/eve-provider.ts) returns capture: "content" alongside tracePolicy, kept "for backwards compatibility". eve ≥0.62 rejects the key by presence (Object.hasOwn(provider, "capture")), so every request fails at startup:

Error: The instrumentation provider "instrumentation/braintrust" no longer supports `capture`. Use `tracePolicy` to configure content capture.
    at registerInstrumentationProvider (…/eve.mjs)
Node.js process exited with exit status: 1.

Repro: npx eve@latest init x && cd x && eve add instrumentation/braintrust && eve build, then send any request to the deployment.

Removing the key (const { capture, ...provider } = braintrustEveInstrumentation(...)) makes it boot.

2. eve.turn spans carry no input or output

With the key removed, eve.step spans log the full prompt and the model response, but eve.turn spans have input and output null. handleTurnStarted / handleTurnTerminal record lineage and metadata only. The older braintrustEveHook logged the user message and final reply on the turn span, and Braintrust features that read the turn row (Topics, facets) now see empty rows.

Expected
  • No capture key when the host eve version supports tracePolicy (or drop it, since eve <0.62 is the only consumer).
  • eve.turn input = the turn's user message, output = the final assistant reply, as the hook integration did.
Dominant language
TypeScript
Stars
28
Forks
14
Avg merge
1d 23h
Merged PRs (30d)
71

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