fix(subscription): resolve same-timestamp webhook ties by refetching latest state

[SumitKumar-17]

…latest state (#268)

What kind of change does this PR introduce?

Bug fix, feature, docs update, ...

What is the current behavior?

Please link any relevant issues here.

What is the new behavior?

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📥 Commits

Reviewing files that changed from the base of the PR and between 6b9c0b2 and 45da4a3.

📒 Files selected for processing (2)

• packages/fastify-app/src/test/subscriptionTimestampTieBreak.test.ts
• packages/sync-engine/src/stripeSync.ts

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📝 Walkthrough

Summary by CodeRabbit

• Tests

  • Added comprehensive validation for subscription event handling when multiple updates occur within the same second.

• Bug Fixes

  • Enhanced subscription state synchronization to correctly handle rapid consecutive updates that occur within the same second. The system now ensures all changes are properly applied and the latest subscription status, billing cycle information, and related details remain accurate.

Walkthrough

A new test file validates tie-breaking behavior for Stripe subscription events occurring within the same second. The sync engine has been enhanced with a conflict-resolution mechanism that detects when two subscription updates share identical timestamps. When this condition is detected, the system refetches the latest subscription state from Stripe and applies it with a fresh timestamp, ensuring deterministic state handling during concurrent webhook processing.

Sequence Diagram(s)

sequenceDiagram
    participant Webhook as Webhook Event
    participant StripeSync as StripeSync
    participant DB as Database
    participant Stripe as Stripe API
    
    Webhook->>StripeSync: processEvent (same timestamp)
    StripeSync->>DB: upsert subscription
    StripeSync->>DB: query subscriptions with same last_synced_at
    DB-->>StripeSync: existing row found
    StripeSync->>Stripe: subscriptions.retrieve()
    Stripe-->>StripeSync: latest subscription state
    StripeSync->>DB: upsert with fresh timestamp
    DB-->>StripeSync: complete
    StripeSync-->>Webhook: success

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[andrejpavlovic]

Shouldn't this be solved for all objects not just subscriptions? It just so happens that we found this issue with subscriptions, but it may apply to other models as well.

[SumitKumar-17]

@andrejpavlovic Yeah i think you are correct. last_synced_at conflict protection is generic, so same-second tie behavior can affect any object. I suppose the repo maintainer of Supabase can continue here as this issue would require a lot of changes