braintrust-tracing

# Braintrust Tracing for Claude Code Comprehensive guide to tracing Claude Code sessions in Braintrust, including sub-agent correlation. ## Architecture Overview ``` PARENT SESSION +---------------------+ | SessionStart | | (creates root) | +----------+----------+ | +----------v----------+ | UserPromptSubmit | | (creates Turn) | +----------+----------+ | +--------------------+--------------------+ | | | +---------v--------+ +--------v--------+ +--------v--------+ | PostToolUse | | PostToolUse | | PreToolUse | | (Read span) | | (Edit span) | | (Task - inject) | +------------------+ +-----------------+ +--------+--------+ | +----------v----------+ | SUB-AGENT | | SessionStart | | (NEW root_span_id)| +----------+----------+ | +-------...