~anthropic/claude-sonnet-latest → B (80:20)

Side B implements a complete, non-trivial feature end-to-end (new HtmlUiAction, server rendering logic, markdown formatting, integration tests, browser test, and docs) that adds real user-facing value. Side A is a set of test-infrastructure bugfixes (regex split, redirect header fix, error handling) that only restore CI/test reliability without adding product functionality, making it valuable but comparatively minor and narrowly scoped to test tooling.