Add hassette_event_buffer_size configuration field

[jessica-claude]

Description

The Hassette core event stream buffer size is currently hardcoded to 1000 items, while the web API event buffer is configurable via web_api_event_buffer_size (default 500). This inconsistency makes it impossible for users to tune the core stream buffer based on their event volume.

Current code (core.py:90):

self._send_stream, self._receive_stream = create_memory_object_stream[...](1000)

Config precedent (config.py):

web_api_event_buffer_size: int = Field(default=500, ...)

Motivation

• Users with high event volume may need larger buffers to prevent backpressure
• Users with low event volume may want smaller buffers to reduce memory footprint
• Consistency: if web_api_event_buffer_size is configurable, core stream should be too
• Tunability: event buffer size affects performance and should be user-controlled

Acceptance Criteria

• Add hassette_event_buffer_size field to HassetteConfig (default 1000 to preserve current behavior)
• Update core.py line 90 to use self.config.hassette_event_buffer_size instead of hardcoded 1000
• Add docstring explaining what this controls and when users might tune it
• Add test in test_config.py verifying the field exists and defaults to 1000
• Update documentation if config is documented elsewhere

Source

Identified during codebase audit on 2026-02-26.