Changes

Replaces Vec<u8> with bytes::Bytes for compressed telemetry data to eliminate expensive memory clones in the upload path, especially critical for retry scenarios.

Problem

The upload_batch() method was cloning the entire compressed payload (potentially MBs) on every upload attempt:

// Before: client.rs:141
self.uploader.upload(batch.data.clone(), ...) //  Vec::clone() copies entire 1+ MB buffer

Impact for a 1 MB batch with 3 retry attempts:

• 3 MB of unnecessary heap allocations (one per retry)
• ~300 µs wasted on memcpy operations

Solution

Changed EncodedBatch.data from Vec to bytes::Bytes:

  // After: client.rs:141
  self.uploader.upload(batch.data.clone(), ...) // Bytes::clone() is O(1) refcount increment

How it works:

1. Bytes::from(Vec<u8>) does NOT copy - it takes ownership of the Vec's allocation and wraps it in a reference-counted container (zero-copy conversion)
2. Bytes::clone() just increments an atomic refcount - no data is copied
3. Both original and cloned Bytes point to the same underlying buffer

Why Bytes instead of Arc?

While Arc<Vec<u8>> would also provide cheap cloning, Bytes is the better choice for our HTTP upload use case:

1. Native reqwest integration: reqwest::Body has impl From<Bytes> that wraps the buffer directly without copying (used at uploader.rs:242). With Arc, we'd need to pass .as_ref() (giving &[u8]), which causes reqwest to allocate internally when converting to Body.
2. Industry standard for async I/O: Bytes is the standard type for byte buffers in Rust's async ecosystem (tokio, hyper, reqwest), ensuring optimal integration.
3. Future optimizations: Bytes::slice() provides zero-copy views into the buffer, which could be useful for - Optimizing Bond encoding pipeline (bond_encoder.rs, central_blob.rs) if we identify unnecessary intermediate copies during schema/event serialization.

Merge requirement checklist

• CONTRIBUTING guidelines followed
• Unit tests added/updated (if applicable)
• Appropriate CHANGELOG.md files updated for non-trivial, user-facing changes
• Changes in public API reviewed (if applicable)