Feature Inventory & Architectural Traces

This catalog documents the 12 core architectural feature groups implemented in 18-flash-sale-inventory, covering all 92 features defined in FEATURES.csv.

Feature Matrix Summary

Feature ID	Feature Name	Primary Source Files	Invariant / Guarantee	Priority
F1	Atomic Inventory Reservation	`stock/reservation.py`	Single-query conditional decrement; zero oversell ($A \ge 0$).	P0
F2	Virtual Waiting Room Queue	`flow/waiting_room.py`	FIFO token bucket admission; cryptographic ticket verification.	P0
F3	Hold Expiration & Rollback	`stock/reservation.py`, `flow/checkout.py`	300-second hold lease TTL; automatic stock recycling on timeout.	P0
F4	Real-Time Oversell Detector	`observability/oversell.py`	Continuous mathematical invariant audit ($A + R + S == T$).	P0
F5	Live Storefront & Telemetry	`frontend/src/app.js`	Real-time DOM telemetry, sell-through gauges, instant reservation modal.	P1
F6	Distributed Locks with Fencing	`transactions/distributed_lock.py`	Monotonic fencing tokens; stale write rejection.	P0
F7	Optimistic Concurrency Control	`transactions/optimistic.py`	Version column matching with bounded exponential backoff retries.	P0
F8	Pricing & Promotions Engine	`pricing/pricing.py`, `pricing/promotions.py`	Original price preservation, price floor validation, stacking rules.	P1
F9	Scheduled Activation & Timezones	`sales/activation.py`	<= 1.0s activation tolerance; DST boundary crossing handling.	P0
F10	Auth, Lockout & Sessions	`auth/service.py`, `models/users.py`	PBKDF2 hashing, exponential cool-down lockout, session token rotation.	P1
F11	Payment Resilience & Refunds	`flow/order_payments.py`	Idempotent payment retry, capped refunds, order cancellation.	P0
F12	Request Throttling & Quotas	`flow/throttling.py`	Token bucket rate limiting, burst smoothing, per-SKU user limits.	P0