TableKeeper: Autonomous Dark Factory

TableKeeper is an autonomous clean-room clone of an enterprise restaurant reservation platform engineered entirely within BAND Desktop using the ArchitectOS Dual-System Factory methodology. Under extreme parallel traffic, network retries, and cross-timezone scheduling, a table must NEVER be double-booked. We achieved this through serialized SQLite WAL transactions (BEGIN IMMEDIATE;), strict interval overlap arithmetic, and idempotency key journaling. The factory topology features three autonomous seats: - @planner (ArchitectOS System-2 Blueprint Engine): Synthesizes EARS requirements, relational schemas, API contracts, and concurrency invariant checklists. - @builder (Implementation Specialist): Implements FastAPI endpoints, atomic SQLite write transactions, and offline Docker packaging. - @verifier (System-1 Deterministic Gating): Enforces multi-tier quality gates, contract audits, and 50-worker parallel race tests. During Stage 1 development, @builder's initial deferred lock was caught by @verifier's 25-thread stress test (double-booking caught). @verifier issued a formal rejection report (VERIFIER-CONC-01). @builder autonomously refactored the transaction boundary to BEGIN IMMEDIATE;. Re-testing proved zero double-booking with 100% pass rate without human intervention. We delivered all 4 graded stages: - Stage 1: Baseline service with zero double-booking guarantee and responsive UI. - Stage 2: Real-time dynamic slot availability search with in-memory interval pre-filter. - Stage 3: Multi-timezone engine (PST, EST, London, Tokyo) and atomic waitlist auto-promotion. - Stage 4: Production hardening with operational telemetry (/api/metrics) and 50-worker race tests. Builds and serves 100% offline inside a Docker container with zero outbound network.