- guard as CEK special form in evaluator.sx, desugars to call/cc +
handler-bind with sentinel-based re-raise (avoids handler loop)
- bootstrap.py: fix bind_lambda_with_rest type annotations, auto-inject
make_raise_guard_frame when transpiler drops it
- mcp_tree: add timeout param to sx_test (default 300s)
- 2566/2568 tests pass (2 pre-existing scope failures)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>