## Fix Summary **Root Cause**: The `PlowApp` class in `src/trckr_plow/tui/app.py` was shadowing Textual's internal attributes with incompatible types: 1. `self._start_time` was being set to `datetime | None` after `super().__init__()`, but Textual's `App.__init__` sets `_start_time = perf_counter()` (a `float`) which is needed in `App._ready()` to calculate startup time. 2. `self._running` was also being shadowed, which could cause issues with Textual's internal state machine. **The Fix** (lines 182-183): - Renamed `_start_time` to `_workflow_start_time` - Renamed `_running` to `_workflow_running` All references throughout the file were updated accordingly (8 occurrences of `_running`, 3 occurrences of `_start_time`). **Verification**: - PlowApp instantiation test passes - Textual's `_start_time` is now correctly a float (from `perf_counter()`) - 810 tests pass (2 pre-existing failures unrelated to this change - they test mmdc installation behavior)