feat(email): abandoned checkout email, 80% free tier warning, credits exhausted email

[waleedlatif1]

Summary

• Handles `checkout.session.expired` Stripe webhook — sends plain personal email from Emir when a user starts an upgrade but doesn't complete it
• Lowers free tier usage warning email from 90% → 80%
• Adds structured credits exhausted email when free users hit 100% — "your workflows are paused, upgrade to continue" with Pro features list and upgrade CTA

Type of Change

• New feature

Testing

Tested manually

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)

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1 Skipped Deployment

Project	Deployment	Actions	Updated (UTC)
docs	Skipped		Apr 3, 2026 2:29am

[cursor]

PR Summary

Medium Risk
Introduces new Stripe webhook-driven and usage-threshold-driven outbound emails, which can impact customer communications volume and correctness if event/threshold logic misfires. Changes are scoped to notifications email flows and templates, not core billing state transitions.

Overview
Adds two new notification email flows: a plain-text-style personal follow-up when a checkout.session.expired (subscription-mode) Stripe event occurs, and a branded CreditsExhaustedEmail sent when free users cross 100% usage (with upgrade CTA and Pro feature list).

Adjusts free-tier upgrade nudges to trigger at 80% (and updates subject/footer copy), while restricting the existing 80% budget warning email to paid users only. Also centralizes “plain email” styling and Pro feature constants, updates EmailLayout to use the wordmark logo, and reclassifies lifecycle emails to emailType: 'notifications'.

^{Written by Cursor Bugbot for commit 034b0f9. Configure here.}

[greptile-apps]

Greptile Summary

This PR adds three email touchpoints for billing lifecycle events: an abandoned checkout recovery email (personal tone, from the founder), a lowered free-tier 80% usage warning (down from 90%), and a new credits-exhausted email when free users hit 100%.

Key changes:

• checkout.ts — New handleAbandonedCheckout handler wired to checkout.session.expired; correctly guards on session.mode === 'subscription' and isProPlan (covers Pro/Team/Enterprise) so neither payment/setup sessions nor already-subscribed users trigger the email.
• usage.ts — Restructures the threshold logic: paid users receive the budget-warning email at 80%; free users receive the upgrade nudge at 80% (lowered from 90%), and a new credits-exhausted email at 100%. The three blocks are mutually exclusive and the early-return pattern from the paid-user block cannot skip the free-user 100% block.
• lifecycle-email.ts — emailType changed from 'transactional' to 'notifications'; the onboarding followup email now correctly respects unsubscribeNotifications preferences and receives List-Unsubscribe headers via the mailer's processEmailData path.
• plainEmailStyles / proFeatures — Shared across onboarding-followup-email, abandoned-checkout-email, and the two billing upgrade emails; eliminates the inline duplication that existed before.
• wordmark.png — Updated logo asset in EmailLayout with explicit width=107 height=33 dimensions to prevent layout shift in email clients.

Confidence Score: 5/5

Safe to merge — previous P0/P1 concerns have been fully addressed and no new issues were found.

All three prior review threads (subscription-mode filter, existing-subscriber guard, preview-text duplication) are resolved in this commit. The threshold logic in usage.ts is correctly structured: the three email paths (paid 80%, free 80%, free 100%) are mutually exclusive by construction, and the early-return guards cannot interfere with one another. No security, data-loss, or correctness issues remain.

No files require special attention.

Important Files Changed

Filename	Overview
apps/sim/lib/billing/webhooks/checkout.ts	New handler for checkout.session.expired; correctly filters to subscription-mode only and gates on isProPlan (covers Pro, Team, and Enterprise) before sending the abandoned checkout email.
apps/sim/lib/billing/core/usage.ts	80% threshold now correctly splits paid vs free users; 90% free-user block replaced by 100% credits-exhausted block; logic is mutually exclusive and the early-return pattern cannot accidentally skip the 100% block.
apps/sim/components/emails/billing/credits-exhausted-email.tsx	New structured email component for free-tier credit exhaustion; uses shared EmailLayout, proFeatures constant, and dollarsToCredits helper — consistent with FreeTierUpgradeEmail patterns.
apps/sim/components/emails/billing/abandoned-checkout-email.tsx	Plain personal email component matching the onboarding-followup pattern; shares plainEmailStyles and has a distinct Preview text per the prior review feedback.
apps/sim/background/lifecycle-email.ts	Changed emailType from 'transactional' to 'notifications' — the onboarding followup email now correctly respects notification unsubscribe preferences and receives List-Unsubscribe headers.
apps/sim/components/emails/_styles/base.ts	Extracted inline plainEmailStyles from onboarding-followup-email into the shared styles module; allows abandoned-checkout-email to reuse the same plain-text look without duplication.
apps/sim/components/emails/billing/constants.ts	New shared config file for proFeatures; correctly uses as const and is imported directly by both FreeTierUpgradeEmail and CreditsExhaustedEmail.
apps/sim/lib/auth/auth.ts	Wires checkout.session.expired to the new handleAbandonedCheckout handler; minimal change, follows existing webhook dispatch pattern.

Flowchart

%%{init: {'theme': 'neutral'}}%%
flowchart TD
    A[Stripe Webhook] --> B{Event Type}

    B -->|checkout.session.expired| C{session.mode === subscription?}
    C -->|No| D[Skip — payment/setup session]
    C -->|Yes| E{User found by stripeCustomerId?}
    E -->|No| F[Log warn & return]
    E -->|Yes| G{isProPlan?}
    G -->|Yes| H[Skip — already subscribed]
    G -->|No| I[Send AbandonedCheckoutEmail\nfrom Emir, emailType: notifications]

    B -->|Usage update| J[maybeSendUsageThresholdEmail]
    J --> K{isFreeUser?}

    K -->|No — Paid user| L{crosses80%?}
    L -->|Yes| M[Send UsageThresholdEmail\nbudget warning]
    L -->|No| N[No email]

    K -->|Yes — Free user| O{crosses100%?}
    O -->|Yes| P[Send CreditsExhaustedEmail\nworkflows paused]
    O -->|No| Q{crosses80%?}
    Q -->|Yes| R[Send FreeTierUpgradeEmail\nupgrade nudge at 80%]
    Q -->|No| S[No email]

    style I fill:#e8f5e9
    style P fill:#ffebee
    style R fill:#fff3e0
    style M fill:#e3f2fd

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