Function run_verification 

pub async fn run_verification(
    root: &Path,
    verify_command: Option<&str>,
) -> Option<VerificationOutcome>

Run a ground-truth verification in root, sandboxed to the workspace: the explicit verify_command if set, else an auto-detected test runner. Returns None when there is nothing to run (no command and no recognized project), so callers can fall back to a softer review.

This is the compiler/test-backed signal that turns a verifier from “an LLM’s opinion” into “it actually ran” — the strongest verification signal there is.