Vibe Code Cleanup for SaaS

Tenant Leaks, Billing Gaps, and Broken Auth

Multi-tenancy is the hardest thing to get right in a SaaS platform. AI code generators get it wrong almost every time. They’ll generate a tenant_id column and add a WHERE clause to the main query, then completely forget about it in the admin dashboard, the background job processor, the cache layer, and the search index.

The result is a SaaS platform that appears to work perfectly in development - because you’re testing with one account. The moment you have two real customers, data starts leaking. Customer A sees Customer B’s records in a search result. A background job processes data for the wrong tenant. A cached dashboard metric includes all tenants instead of just one. These aren’t edge cases. They’re the default outcome of AI-generated multi-tenant code.

Billing is the second landmine. AI tools generate Stripe integration code that creates subscriptions and processes charges. But they don’t handle the forty edge cases that actually matter: mid-cycle upgrades, prorated downgrades, failed payment retries, subscription pauses, tax calculation, metered billing overages, and invoice discrepancies. Each missed edge case is revenue you’re losing or customers you’re overcharging.

API authentication is the third problem. AI-generated endpoints use different auth patterns depending on which training example the model drew from. Some endpoints check JWT tokens. Others check API keys. Some check both. Some check neither. There’s no consistent middleware, no standard pattern, and no rate limiting. Your API is a patchwork of authentication approaches, and at least a few endpoints have holes.

Isolation, Billing, and API Hardening

Tenant isolation failures. We audit every database query, cache operation, background job, search query, file storage access, and API response for tenant scoping. We find every place where data can leak between tenants - and there are always more than you expect. We implement row-level security or query-scoping middleware that makes it structurally impossible to access another tenant’s data, not just convention-dependent.

Billing edge cases. We map your entire subscription lifecycle and identify every edge case your AI-generated code doesn’t handle. Failed payments that silently cancel accounts. Upgrades that don’t prorate correctly. Trial expirations that don’t trigger the right webhooks. We fix each one and add Stripe webhook handlers that are idempotent and reliable.

API auth inconsistencies. We standardize authentication across every endpoint. One pattern. One middleware. Consistent token validation, scope checking, and error responses. Then we add rate limiting to prevent abuse and ensure your API can handle misbehaving clients without affecting other customers.

Missing webhook reliability. AI-generated webhook handlers process events once and assume success. We add idempotency checks, signature verification, retry handling, and dead letter queues so you never miss a billing event or integration callback.

How We Audit and Fix Incrementally

We start with tenant isolation because it’s the highest-risk issue. We run automated queries across your database to detect data that’s accessible outside its tenant scope. We trace every background job, cache key, and search index to verify tenant boundaries. This audit produces a concrete list of isolation failures ranked by severity.

Fixes roll out incrementally. We add tenant-scoping middleware that applies globally, then verify it against existing behavior. We add row-level security policies in the database as a second enforcement layer. Every fix gets a tenant isolation test that creates two tenants, operates as one, and verifies the other’s data is completely inaccessible.

For billing, we build a test harness that simulates every subscription lifecycle event: creation, upgrade, downgrade, cancellation, reactivation, failed payment, and recovery. We verify that your system handles each correctly and that Stripe’s state always matches your application’s state.

API standardization happens last because it touches every endpoint. We introduce auth middleware systematically, endpoint by endpoint, verifying that existing integrations continue to work. Rate limiting deploys per-tenant so one customer’s API usage can’t degrade performance for others.

Enterprise-Ready with Accurate MRR

Your SaaS platform is enterprise-ready. Tenant data is isolated at the query level, the cache level, and the infrastructure level. A potential customer’s security review won’t find cross-tenant data access because it’s structurally prevented, not just conventionally avoided.

Billing is accurate. Subscriptions handle every lifecycle event correctly. Your MRR reporting matches Stripe’s numbers. You stop losing revenue to edge cases and stop overcharging customers by accident.

Your API is consistent and hardened. Every endpoint uses the same auth pattern. Rate limiting protects your infrastructure. Webhooks are reliable. Your team can add new endpoints and features on a foundation that enforces the right patterns automatically.