E5-F4: Purchase Window Enforcement

Epic: E5: Waiting Queue System

Size: S (Small)

Problem / Outcome

User has 20 minutes to complete purchase once at front of queue.

Scope

In-Scope:

• 20-minute window starts when user reaches front
• Cart TTL tied to purchase window
• Window expiration handling

Out-of-Scope:

• Window extension

Acceptance Criteria

• AC1: When user reaches front, 20-minute purchase window starts
• AC2: If window expires, user removed from queue and must rejoin at end
• AC3: Notification sent when window expires: "Your purchase window has expired"

Data Model Impact

QueueEntry table:
- window_started_at (TIMESTAMP, nullable)
- window_expires_at (TIMESTAMP, nullable)
- status (ENUM includes: window_expired)

Window expiration triggers:
- Release reserved seats
- Remove from active queue
- Send expiration notification

Permissions/Roles

• System

How to Verify

npm test -- --grep "purchase window"

Expected: Window enforced, expiration handled correctly.

Dependencies

• E5-F1: Queue Join and Position Assignment
• E4-F4: Cart Management with TTL

Implementation Tasks

See E5: Waiting Queue Tasks

Doc References

• Waiting Queue Flow

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Last Updated: January 2026