fix(core): Remove check and always respect ai.telemetry.functionId for Vercel AI gen spans

[RulaKhaled]

This PR fixes a mismatch between ai.telemetry.functionId and gen_ai.function_id. Function ids were ignored unless the span name contained exactly one dot. This caused:

• gen_ai.function_id to be missing or inconsistent for valid generation spans.
• Mismatch between ai.telemetry.functionId and gen_ai.function_id, making trace exploration and metrics harder to interpret.

We now always respect experimental_telemetry.functionId when present, where function id could be set as part of request.

---

Note

Always update Vercel AI generate span names and set gen_ai.function_id when experimental_telemetry.functionId is present, removing the dot-count check.

• Core (Vercel AI span processing):
  • In packages/core/src/utils/vercel-ai/index.ts processGenerateSpan:
    • Remove name.split('.') dot-count check; always apply experimental_telemetry.functionId.
    • When present, append function ID to the operation name and set gen_ai.function_id.
    • Clarify comments on telemetry function ID usage.

^{Written by Cursor Bugbot for commit 4b9fa48. This will update automatically on new commits. Configure here.}

[linear]

JS-992 Investigate Inconsistent Function ID in Span Attributes

[github-actions]

node-overhead report 🧳

Note: This is a synthetic benchmark with a minimal express app and does not necessarily reflect the real-world performance impact in an application.
⚠️ Warning: Base artifact is not the latest one, because the latest workflow run is not done yet. This may lead to incorrect results. Try to re-run all tests to get up to date results.

Scenario	Requests/s	% of Baseline	Prev. Requests/s	Change %
GET Baseline	9,350	-	8,980	+4%
GET With Sentry	1,322	14%	1,409	-6%
GET With Sentry (error only)	5,974	64%	5,974	-
POST Baseline	1,171	-	1,210	-3%
POST With Sentry	496	42%	519	-4%
POST With Sentry (error only)	1,031	88%	1,051	-2%
MYSQL Baseline	3,262	-	3,269	-0%
MYSQL With Sentry	402	12%	475	-15%
MYSQL With Sentry (error only)	2,636	81%	2,678	-2%

View base workflow run