Three-tier batching refactor: replace alphabetical 4-at-a-time batching with
fixture-class-isolated tiers (0 opt-in, 1 unit/xdist, 2 mock_app, 3 live_gui
in one session, H headless, P performance).
Hybrid classification: auto-infer from filename + AST fixture scan; hand-curated
tests/test_categories.toml overrides for cross-cutting and ambiguous files.
Opt-in per-test order control via [[files.X.test_order]] sub-tables, gated on
a conftest-loaded pytest plugin (no-op without entries).
Priority order: B (process isolation) > A (subsystem diagnostic) > C (speed).
ed
b7a9737443