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# AI 3.8-15.1.6 Release Notes

## Summary

### New Features

* **A new cluster-info API endpoint** provides a simpler way to query cluster status programmatically.

### Major Enhancements

* **Cold-read performance is a major focus of this release.** Cold-read behavior is improved by removing serialized S3 GET bottlenecks, reducing small-read fetch amplification, and improving worker-side read execution so read-heavy workloads spend less time stalled on the page store or self-loopback paths.
* **Read-path execution efficiency** is further improved through Netty worker-pool tuning and related read-path optimizations, helping the system stay more stable under sustained read pressure.
* **S3 API semantic compatibility** is materially improved. `ListObjects` behavior is brought closer to AWS S3 expectations, missing buckets now return `NoSuchBucket` instead of a generic server error, invalid range requests return the expected range error, and response headers such as `Content-Encoding` and `Accept-Ranges` are handled more correctly.
* **S3 read behavior in worker-owned and proxy scenarios** is improved through zero-copy path simplification and better handling of worker-owned segments, reducing avoidable stalls in affected read flows.

### Bug Fixes

* **S3 write cache reliability fixes** address cache eviction races, multipart placeholder races, and pinned-empty-file recovery after restart.
* **A direct-memory leak in the S3 HTTP path** is fixed, preventing large sustained-memory growth under load.
* **FUSE write hangs** triggered by unrecoverable worker-side errors are fixed.
* **Hash-ring mismatch handling** is corrected so ghost-worker states no longer cause duplicate segments or unnecessary UFS reads.
* **S3 API correctness fixes** improve list semantics, missing-bucket handling, invalid-range handling, and response-header correctness.
* **Operational fixes** improve Docker collect-info behavior and reduce noisy or misleading logs in FUSE deployments.

## Breaking Changes

No breaking changes in this release.

## Upgrade Notes

No migration steps are required for this release.