feat(billing): implement subscription trial management with conversion optimization

[ayomideadeniran]

Summary

Implements comprehensive subscription trial management with dynamic conversion optimization across Soroban smart contracts and billing backend services.

Key Changes

1. Smart Contracts (contracts/subscription/src/)

• Added trial.rs Soroban contract module defining OnChainTrialConfig, OnChainTrialRecord, OnChainTrialStatus, and TrialConversionMetrics.
• Implemented authenticated trial operations: configure_trial_for_plan, start_trial, extend_trial, convert_trial, and evaluate_trial_expiration supporting grace periods and automatic conversion.
• Registered module in contracts/subscription/src/lib.rs.

2. Backend Billing Service (backend/services/billing/)

• Implemented TrialManagementService in backend/services/billing/trialManagementService.ts:
  • Trial Enrollment & Policy: Configurable trial durations (7, 14, 21, 30 days), grace periods, and auto-conversion toggles.
  • Propensity-to-Convert Engine: Weighted multi-signal scoring model (feature actions, logins, active days, dashboard views, exports) categorizing users into high_propensity, medium_propensity, at_risk, and disengaged.
  • Dynamic Conversion Incentives: Automated targeted promotional discounts and trial extension rewards.
  • Automated Reminder Queue: Multi-stage notifications (D-3, D-1 with promo codes, D-Day, and grace period final).
  • Auto-Conversion Pipeline: Scheduled job evaluation converting expired trials with applied discount BPS.
  • Conversion Funnel Analytics: Aggregates conversion rates, average conversion velocity, and attributed revenue.
• Exported in backend/services/billing/index.ts.

3. Tests & Verification

• Added backend/services/billing/__tests__/trialManagementService.test.ts with 13 comprehensive unit tests covering:
  • Policy configuration and trial start
  • Propensity scoring and dynamic incentive assignment
  • Extension limits and reason tracking
  • Manual conversion and automated expiration/auto-conversion
  • Reminder dispatching and revenue attribution metrics

Closes #958

[drips-wave]

@ayomideadeniran Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits