LangSmith SDK 0.12.0 makes redaction failures block traces

LangSmith's SDK 0.12.0 changes what happens when a trace anonymizer breaks, dropping the trace instead of shipping it unredacted.

The old behavior let unredacted data ship anyway when a redaction function broke. Now a broken anonymizer makes the trace vanish, leaving a gap in the dashboard that's easy to miss until someone needs the missing trace.

The release also makes trace sampling deterministic and switches the SDK's HTTP layer to httpx2, with httpx kept as a fallback, per 0.12.0's release notes.

It's a real fix. Silent data exposure is worse than a missing trace. But the fix moves the burden from security to observability. Teams should test custom anonymization callables against malformed input before the upgrade, not after an incident review turns up a week of missing traces.

The release notes don't say whether the SDK emits a warning or a metric when a trace gets dropped this way. That gap decides whether teams catch it before it costs them something.