fix(billing): make subscription table source of truth for period start and period end

[icecrasher321]

Summary

Make periodEnd and periodStart from subscription table source of truth, and remove cron job so all user_stats updates happen on Stripe webhook call.

Type of Change

• Bug fix

Checklist

• Code follows project style guidelines
• Self-reviewed my changes
• Tests added/updated and passing
• No new warnings introduced
• I confirm that I have read and agree to the terms outlined in the Contributor License Agreement (CLA)

[vercel]

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Project	Deployment	Preview	Comments	Updated (UTC)
sim	Ready	Preview	Comment	Aug 23, 2025 3:03am

1 Skipped Deployment

Project	Deployment	Preview	Comments	Updated (UTC)
docs	Skipped			Aug 23, 2025 3:03am

[greptile-apps]

Greptile Summary

This PR fixes critical billing reliability issues by improving the daily billing period detection logic and enabling Vercel cron job authentication. The main changes involve three key areas:

Billing Period Detection Enhancement: The core change replaces exact timestamp matching (periodEnd.getTime() === today.getTime()) with range-based date comparisons (periodEnd >= today && periodEnd < tomorrow) in billing.ts. This addresses timing precision issues that could cause billing cycles to be missed due to timezone differences or database timestamp variations.

Safety Net Implementation: The PR restructures the billing fallback logic to always check userStats.billingPeriodEnd as a secondary validation, rather than only when subscription.periodEnd is missing. This ensures that stale subscription period data doesn't prevent billing from occurring, which is critical for revenue integrity.

Vercel Cron Authentication: The authentication system is updated to support Vercel's native cron jobs by accepting the x-vercel-cron: 1 header as an alternative to Bearer token authentication. This enables the billing system to run as a scheduled Vercel cron job.

API Consolidation: The daily billing endpoint is simplified by converting from separate POST/GET endpoints to a single GET endpoint that handles both health checks and actual billing processing.

These changes work together to create a more robust billing system that can handle edge cases with stale data and timing discrepancies while enabling deployment on Vercel's platform with native cron functionality.

Confidence score: 4/5

• This PR addresses critical billing reliability issues with well-reasoned solutions that improve system robustness
• Score reflects solid technical approach to handling timing edge cases and authentication requirements, with clear business impact
• Pay close attention to the authentication changes in internal.ts and the behavioral change in the daily billing endpoint

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