Why: a lost write response was keeping the old duty version, so the next save replayed it, and a busy save could stay locked if another request advanced the sequence.
Evidence: SELF vitest duty-draft 6 passed, tsc passed, knip 43, Playwright duty flows 3 passed.
Impact: an unknown save reloads server roles, confirmation resets, and busy clears even if a later read is discarded.
Refs: docs/proposals/2026-10-15-rdm-duty-matrix-rework.md
Co-authored-by: Cursor <cursoragent@cursor.com>