Summary

This change moves dataset generation buffer sizing into RunConfig, making runtime execution settings explicit and centralized.

• Add RunConfig.buffer_size (default: 1000, validated via Field(gt=0)).
• Make ColumnWiseDatasetBuilder.build(...) read buffer_size from ResourceProvider.run_config (removes the explicit buffer_size argument).
• Remove DataDesigner’s buffer configuration helper (set_buffer_size) and its internal _buffer_size state.
• Update unit tests to configure buffer sizing via RunConfig.

Motivation

Previously, buffer sizing lived on DataDesigner via a separate helper method, while other runtime/execution controls (early shutdown, retry limits) lived on RunConfig. That split made it harder for users to discover, reason about, and persist “how generation runs” settings.

By consolidating buffer_size into RunConfig, all runtime knobs that affect execution behavior now live in one place, and the engine consistently reads them from a single source (ResourceProvider.run_config). This clarifies dataset generation settings, makes configs easier to share/reuse, and reduces the chance of configuration drift between interface and engine.

Behavior / impact

• Default behavior is unchanged: if users do nothing, RunConfig().buffer_size == 1000.
• buffer_size controls end-to-end batch size during persisted generation: one batch is generated, post-batch processors run, and the batch is written to artifact storage before the next batch begins.
• Breaking change: DataDesigner.set_buffer_size(...) was removed. Buffer sizing is now configured only via RunConfig.

Usage example

from data_designer.essentials import DataDesigner, RunConfig

dd = DataDesigner(artifact_path="./artifacts")

# Configure runtime execution settings in one place
run_config = RunConfig(
    buffer_size=250,  # records per end-to-end batch (generate -> process -> write)
    shutdown_error_rate=0.3,
    shutdown_error_window=25,
)

dd.set_run_config(run_config)

results = dd.create(config_builder, num_records=10_000)

Tests

• Updated interface and engine builder tests to validate default + configured buffer_size behavior and to reflect the removed helper API.