Subscription Module Design and Development

Define a host-integration boundary for billable owners, authorized actors, and eligible seat assignees using stable owner-type and owner-ID references that support individuals and teams.

Implement versioned TypeORM plan and price entities for fixed recurring fees, per-seat fees, billing intervals, currencies, feature entitlements, and retired offerings, storing monetary amounts in minor units.

Define and test an explicit subscription state machine with allowed command-driven and provider-event-driven transitions and invariants.

Implement PostgreSQL migrations for subscriptions, billing periods, provider references, and transition audit records, including appropriate unique, foreign-key, and check constraints.

Define a billing-provider contract for customers, checkout, plan and seat-quantity quotes, subscription changes, cancellation, invoices, and authoritative snapshots, including capability flags, stable idempotency keys, and normalized errors.

Implement trial activation, expiration, and trial-to-paid conversion while preventing an unconfirmed payment from activating paid access.

Implement a subscription-change command that uses provider quotes for immediate upgrades or seat increases, schedules downgrades or seat decreases for the next period, and rejects quantities below assigned seats.

Implement immediate and end-of-period cancellation, including reversal of a pending cancellation when the provider supports it.

Apply successful renewal events idempotently so the local billing period advances exactly once.

Apply failed-payment and recovery events using provider-managed dunning status plus configurable local grace-period and access-suspension policies.