Cutover: Catch Lost Writes Before Merge

An old warehouse scanner accepts bin R-07. The migration succeeds, but the new application reads A-01. The schema exists and the completed-rollout tests pass; an acknowledged write was lost between deployment steps. Cutover gives backend and release engineers an executable counterexample before a schema-changing pull request merges. The missing test is the space between versions. Cutover executes old and new SQL adapters on fresh, disposable SQLite databases. After each completed migration statement, it interleaves old-worker updates and inserts, then checks readers against an independent ledger of acknowledged writes. Its unsafe Warehouse plan passes all 76 completed-rollout probes but fails 16 of 48 migration-window probes. The witness retains the SQL boundary, accepted operation, row, expected value and observed value. Press “Run unsafe → Bob repair” in the live demo: 108/124 blocked becomes 116/116 passed on the unchanged contract. Bob’s saved Warehouse repair protects writes before backfill, using one-way synchronization plus explicit dual writes. Different SQL sequences retain separate boundary schedules; Cutover does not claim matching step numbers are equivalent tests. IBM Bob IDE performed two event-period tasks. It saved distinct Parcel and Warehouse repairs, each independently verified at 116/116, and built the original GitHub Actions PR review gate. Its failed recursive-trigger attempt remains in the history. Both required task-session consumption PNGs, full histories, saved candidates and actual red/green/regressed-red PR evidence are public. The offline Bob proof pack includes both original task summaries and saved repairs for local replay. When queued jobs can still write the old column, bring existing schema, migration and worker query files to the local starter. No account, pip install, SQL upload or hand-edited JSON. Compare migration SQL from exact local commits without fetching or checking out code. Repair candidate queries through SQL files. Each review retains the original failure and SQL snapshots, writes an offline PR note, and exports a locked CI kit only after a pass. A blocked custom rehearsal can become a downloadable local Bob repair workspace: fixed evaluator, failing inputs, MCP setup and a repair task, without credentials, automatic approvals or bundled passing solutions. Independent verification refuses changed fixed inputs and retains each candidate attempt. This handoff was checked through the MCP SDK and saved-candidate replay; it is not a new Bob IDE task or proof of another user’s IDE setup. After repair, export a pinned PR-gate kit containing contract, adapters, migration SQL and workflow. The reviewed contract hash flags changed test records as unverified until the lock is deliberately updated. Actual repository controls exercised passing, SQL-only regression and missing-input cases on Windows and Ubuntu. Saved CI ZIPs can be independently replayed and reopened; altered evidence is rejected and editing SQL clears the verdict. The evaluator/browser began as pre-event Codex scaffolding. Bob’s repairs and original gate are the event IDE contribution; later packaging, browser features and controls are Codex extensions. These are synthetic repository controls, not customer adoption. Cutover provides bounded sequential SQLite evidence, not simultaneous transaction coverage, support for other engines or production approval.