run_all() takes an optional substring list; vtest_main forwards argv and a comma-separated $VT_ONLY. No filter => run everything, as before. Makes iterating on one slow end-to-end case (the engine suite) practical without a framework swap. Co-Authored-By: Claude Sonnet 5 <[email protected]> Claude-Session: https://claude.ai/code/session_01HPPSGhiArbvQgwC2DNiURS