Python SDK v1.3.0

New Features and Improvements

• Built on Rust SDK 2.0.1: The Python wrapper now depends on
  databricks-zerobus-ingest-sdk = "2.0.1" from crates.io (was 1.2.0).
  Internal PyO3 binding was rewritten to use the new StreamBuilder
  typestate API exclusively. The Python-facing API surface
  (TableProperties, create_stream(client_id, client_secret, table_properties, options, headers_provider), ingest_record,
  RecordAcknowledgment, etc.) is unchanged.
• Arrow Flight promoted to Beta: ZerobusArrowStream /
  ArrowStreamConfigurationOptions and the surrounding documentation are
  no longer labelled experimental/unsupported. The API is stabilising but
  may still change before reaching GA. (Mirrors the Rust SDK 2.0.1
  promotion.)
• Arrow Flight — graceful stream close: On server signaled close, the client pauses sending, drains in-flight acks within a bounded wait, then recovers.
• stream_paused_max_wait_time_ms on ArrowStreamConfigurationOptions: Optional milliseconds cap for the paused wait (None = full server duration, 0 = immediate recovery).
• Python SDK identifier on the wire: The SDK now reports itself as
  zerobus-sdk-py/<version> on the HTTP user-agent header
  (previously it inherited the Rust SDK identifier
  zerobus-sdk-rs/<rust-version>). Server-side telemetry can now tell
  Python clients apart from Rust clients.
• AckCallback.on_error is now delivered to Python: The PyO3 binding
  previously only logged ack errors via eprintln!; subclasses overriding
  on_error would never see the call. They will now.

Behavior Changes

• StreamConfigurationOptions.record_type is no longer applied: Format
  is now set on the stream builder from TableProperties (proto descriptor
  present → Proto, absent → JSON). The field is kept for API compatibility.

• StreamConfigurationOptions.max_inflight_records default raised from
  50_000 to 1_000_000 to match the Rust SDK 2.0.1 default. Previously the
  Python wrapper hard-coded 50k while the Rust SDK quietly raised its default
  to 1M, so Python clients ran with a 20× lower in-flight ceiling than Rust
  clients for no good reason. Callers who relied on the old cap can pin it
  back explicitly:

  StreamConfigurationOptions(max_inflight_records=50_000)

Bug Fixes

• TableProperties(name, MyMessage.DESCRIPTOR) proto-descriptor
  selection now picks the message by name when a
  google.protobuf.descriptor.Descriptor object is passed. Previously
  the first message in the FileDescriptorProto was always chosen, which
  silently mis-routed schemas for .proto files containing multiple
  messages. Raw-bytes input still falls back to the first message (no
  name hint is available).

Documentation

• Updated docstrings, the Arrow example files, and zerobus.sdk.shared.arrow
  to reflect the Beta promotion.

Internal Changes

• Bumped Rust dependencies to match the Rust SDK 2.0.1 workspace:
  prost / prost-types 0.13 → 0.14, tonic 0.13 → 0.14, arrow-ipc /
  arrow-schema / arrow-array 56.2 → 58.2.
• Removed the in-tree [patch.crates-io] redirect for
  databricks-zerobus-ingest-sdk — the 2.0.1 release is now resolved
  from crates.io.
• StreamConfigurationOptions and ArrowStreamConfigurationOptions
  fields are now applied via StreamBuilder setters because the
  underlying Rust structs are #[non_exhaustive] in 2.0.1.
• Bounded the HeadersProviderWrapper static-key leak: header names are
  now interned in a process-wide table so each distinct name is leaked at
  most once, instead of once per get_headers() call.
• Shared payload-extraction, options-application, and the AckCallback
  bridge moved into python/rust/src/common.rs, removing duplicated code
  between sync_wrapper.rs and async_wrapper.rs.
• ZerobusSdk.set_use_tls(...) is retained as a no-op for backwards
  compatibility. Rust SDK 2.0.1 removed the underlying TLS toggle; TLS is
  always controlled via the SDK builder.