End the Analytics Engine span when a write rejects

[ayaangazali]

instrumentAEFn in packages/otel-cf-workers/src/instrumentation/analytics-engine.ts called span.end() only on the success path, with no try/catch/finally around the wrapped call. So when writeDataPoint rejects, the span is never ended and never exported: the operation disappears from the trace entirely and the failure leaves no trace at all, which is the opposite of what you want from a failed write. Every sibling instrumentation in the package already guards this, for example do-storage.ts records the exception, sets ERROR, and ends the span in a finally.

This applies that same shape here, so a rejected write now ends its span with an exception event and ERROR status and still rethrows the original error unchanged.

The instrumented behavior had no test coverage at all before this, only the attribute helper did, so I added two cases against an InMemorySpanExporter: one for the success path and one for the rejection. The rejection test fails on current main with expected [] to have a length of 1, which is the missing span. Ran pnpm run check from the root, all green. Patch changeset for @pydantic/otel-cf-workers included.

quick disclosure: Claude Code helped me put this together and I read the final diff myself. Freshman still learning my way around the Workers runtime, so corrections welcome :)

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• .changeset/ae-span-error-handling.md
• packages/otel-cf-workers/src/instrumentation/analytics-engine.ts
• packages/otel-cf-workers/test/instrumentation/analytics-engine.test.ts

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• pydantic/logfire (manual)
• pydantic/pydantic-ai (manual)

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📝 Walkthrough

Walkthrough

Analytics Engine instrumentation now wraps writes in try/catch/finally. Successful writes retain their span attributes and query text. Failed writes record exceptions, set span status to ERROR, rethrow the original error, and end the span. Tests cover successful and rejected writes. A patch changeset documents the updated behavior.

Possibly related PRs

• pydantic/logfire-js#200: Adds similar rejection-path OpenTelemetry tests for another instrumentation module.

🚥 Pre-merge checks | ✅ 4

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly describes the main change: ending the Analytics Engine span when a write rejects.
Description check	✅ Passed	The description directly explains the instrumentation fix, added tests, error behavior, and changeset.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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