Try to retain users who did not subscribe

[Blaumaus]

Changes

If applicable, please describe what changes were made in this pull request.

Community Edition support

• Your feature is implemented for the Swetrix Community Edition
• This PR only updates the Cloud (Enterprise) Edition code (e.g. Paddle webhooks, blog, payouts, etc.)

Database migrations

• Clickhouse / MySQL migrations added for this PR
• No table schemas changed in this PR

Documentation

• You have updated the documentation according to your PR
• This PR did not change any publicly documented endpoints

Summary by CodeRabbit

• New Features
  • Automated subscription reminders: eligible users now receive a 14-day trial invitation email highlighting key benefits (web analytics without cookie banners, error tracking, custom events/funnels/goals, privacy-first reCAPTCHA alternative).
  • Daily reminder scheduling with tracking to avoid duplicate sends and record when reminders are dispatched.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 1891ab05-8bc4-4b03-9f7d-14631bf56f87

📥 Commits

Reviewing files that changed from the base of the PR and between 657ad2c and a7e8499.

📒 Files selected for processing (1)

• backend/migrations/mysql/2026_03_10_subscribe_reminder.sql

🚧 Files skipped from review as they are similar to previous changes (1)

• backend/migrations/mysql/2026_03_10_subscribe_reminder.sql

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📝 Walkthrough

Walkthrough

Introduces a subscribe-reminder email system: new HTML template and mailer metadata, a daily cron job that emails eligible free-plan users in their first post-onboarding week, a nullable subscribeReminderSentOn user field, and a migration adding the corresponding DB column.

Changes

Cohort / File(s)	Summary
Email Template & Mailer backend/apps/cloud/src/common/templates/en/subscribe-reminder.html, backend/apps/cloud/src/mailer/letter.ts, backend/apps/cloud/src/mailer/mailer.service.ts	Adds new HTML email template inviting a 14-day free trial. Adds SubscribeReminder to LetterTemplate and registers subject metadata ("Your Swetrix trial is waiting for you").
Scheduled Task & Reminder Logic backend/apps/cloud/src/task-manager/task-manager.service.ts	Adds remindUsersToSubscribe() cron (daily at 10:00) to query free-plan users within a 1-week window post-onboarding, send SubscribeReminder emails with concurrency control, update subscribeReminderSentOn, and log per-user failures. Refines another reminder to exclude free-plan users.
Data Model & Migration backend/apps/cloud/src/user/entities/user.entity.ts, backend/migrations/mysql/2026_03_10_subscribe_reminder.sql	Adds nullable subscribeReminderSentOn timestamp to User entity and creates the corresponding user table column via migration.

Sequence Diagram

sequenceDiagram
    participant Scheduler as Cron Scheduler
    participant TaskMgr as TaskManager Service
    participant DB as Database
    participant Mailer as Mailer Service
    participant UserSvc as User Service

    Scheduler->>TaskMgr: invoke remindUsersToSubscribe() @ 10:00
    TaskMgr->>DB: Query users (PlanCode.none, onboarded, created ~1 week, no subscribeReminderSentOn)
    DB-->>TaskMgr: return user list
    alt users found
        loop per user (bounded concurrency)
            TaskMgr->>Mailer: send SubscribeReminder(email, subscribeUrl)
            Mailer-->>TaskMgr: success / failure
            alt success
                TaskMgr->>UserSvc: set subscribeReminderSentOn(timestamp)
                UserSvc->>DB: persist timestamp
            else failure
                TaskMgr->>TaskMgr: log error for user
            end
        end
    else no users
        TaskMgr->>TaskMgr: exit early
    end

Loading

Estimated code review effort

🎯 3 (Moderate) | ⏱️ ~20 minutes

Poem

🐰 I hopped through code to spread the news,

A trial awaits — no cards to lose.
Cron wakes at ten to send the rhyme,
One field, one migration, one reminder time.
Hooray for trials and tidy queues!

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title accurately captures the main objective of the changeset: implementing a subscribe reminder system to retain users who haven't subscribed to a paid plan.
Description check	✅ Passed	The description follows the template structure with appropriate checkboxes marked, confirming this is Cloud Edition code with database migrations. However, the 'Changes' section is empty, omitting details about what modifications were implemented.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch subscribe-reminder

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In `@backend/apps/cloud/src/user/entities/user.entity.ts`:
- Around line 277-279: The entity property subscribeReminderSentOn is declared
with type: 'timestamp' but the migration creates the column as DATETIME; change
the column definition in the migration that adds the subscribe_reminder (the
2026_03_10_subscribe_reminder.sql migration) to use TIMESTAMP (or TIMESTAMP
NULL) instead of DATETIME so it matches the User entity's
subscribeReminderSentOn and the pattern used by
evWarningSentOn/noEventsReminderSentOn; ensure NULLability and any default
clauses in the SQL match the entity declaration.

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ℹ️ Review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 3fdfaa84-b1be-46a6-9037-a5bed4393b5d

📥 Commits

Reviewing files that changed from the base of the PR and between fc1ff8f and 657ad2c.

📒 Files selected for processing (6)

• backend/apps/cloud/src/common/templates/en/subscribe-reminder.html
• backend/apps/cloud/src/mailer/letter.ts
• backend/apps/cloud/src/mailer/mailer.service.ts
• backend/apps/cloud/src/task-manager/task-manager.service.ts
• backend/apps/cloud/src/user/entities/user.entity.ts
• backend/migrations/mysql/2026_03_10_subscribe_reminder.sql