hkust-taco

Work with HKMC2 DiffTests where golden snapshots are embedded in `.mls` files as `//│ ...` lines and updated in place by the test runner. Use when editing or reviewing files under `hkmc2/shared/src/test/**/*.mls`, running `hkmc2DiffTests` or watcher loops, diagnosing mismatches between diagnostics and expectations (`:e`, `:re`, `:expect`, etc.), or deciding whether rewritten snapshot lines should be committed.