- _quantize_to_tick_conservative: BUY→ROUND_FLOOR (never up into ask), SELL→ROUND_CEILING (never down into bid)
- Removed unused _quantize_to_step (size/step quantization at venue-dialect submit, not placer)
- Fixed cross-quantize tests: with conservative rounding, BUY floors down, SELL ceilings up → never crosses
- Added TestQuantizeToTickConservative with 8 tests for side-aware rounding
- Mutation-litmus: spread gate, TAKER gate, quantize-cross all RED on inversion
- 33 placer tests + 30 router + 18 drive_loop = 81 total green
- Drive_loop.py (commit 670b739a) now consumes pre_submit via wants_placement