I oversimplified my own system while trying to be honest about its gaps

Went through my Stripe webhook handler today, prompted by a conversation about proving system behavior instead of assuming it. Found something, then found I'd described it wrong on the first pass — which turned out to be the more interesting part.

My first read: "the handler syncs subscription state directly from the webhook payload, never re-fetches from Stripe's API." Sounded clean. It was wrong.

Actual behavior, once I checked the code properly: it's a mixed pattern. checkout.session.completed and invoice.paid events call stripe.subscriptions.retrieve() to pull fresh state from Stripe before syncing — genuinely verified against the live source. But customer.subscription.updated and customer.subscription.created sync directly from the webhook payload, no re-fetch at all.

So depending on which event triggers the sync, my system either has real evidence the local state matches Stripe's current state, or it doesn't — and I'd flattened that into one blanket claim without checking each path individually.

The lesson isn't really about Stripe webhooks. It's that "I checked this" and "I checked this carefully enough to catch my own oversimplification" are different levels of rigor, and the second one usually takes an extra pass I'm tempted to skip once the first answer sounds plausible.

Anyone else caught themselves doing this — describing a system's behavior with more confidence than the actual code supported?