ADDED Requirements

Requirement: Plan upgrade detection

The system SHALL detect when a user is upgrading to a higher tier plan.

Scenario: Upgrade detected by higher priority

• WHEN current plan priority is lower than target plan priority within same subscription group
• THEN classify as upgrade operation

Scenario: Same plan - not an upgrade

• WHEN user selects the same plan they currently have
• THEN classify as same-plan (not upgrade or downgrade)

Requirement: Immediate upgrade effect

The system SHALL apply upgraded plan benefits immediately upon successful payment.

Scenario: Upgrade takes effect immediately

• WHEN upgrade payment is successful
• THEN immediately activate new plan benefits for the user

Requirement: Proration for upgrades

The system SHALL calculate and apply prorated refund for unused portion of current subscription.

Scenario: Stripe handles proration

• WHEN processing an upgrade
• THEN rely on Stripe to calculate proration and apply credit/refund

Requirement: Upgrade - no plan stacking

The system SHALL ensure upgraded plan does not stack with existing subscription.

Scenario: Upgrade replaces existing subscription

• WHEN processing upgrade
• THEN terminate old subscription and activate new subscription (no parallel/overlapping)

Requirement: Upgrade trial period handling

The system SHALL not allow upgrades for subscriptions in trial period.

Scenario: Block upgrade during trial

• WHEN user attempts to upgrade while in trial period
• THEN display message explaining upgrade will be available after trial ends