Your OTP regex assumes six digits. Supabase magic links don't.

Sign-in worked flawlessly in dev. Then a real user pasted a real code and got "invalid format" — before the code ever reached Supabase. The credential was fine. My regex was wrong. Here's the one-line assumption that broke auth for every human who wasn't me. I run a Discord-native Company Brain. Teams /save docs and /ask grounded answers; access is gated by a magic-link claim that emails a one-time code. Standard GoTrue OTP flow. The client shows a box, you paste the code, the server verifies it. Boring — which is exactly what auth should be. The bug: a six-digit assumption in a validation guard The claim handler did a cheap client-side sanity check before calling verifyOtp : // The bug. Looks reasonable. Rejects every real code. const OTP = /^ \d{6} $/ ; function normalize ( input : string ): string { const code = input . trim (); if ( ! OTP . test ( code )) throw new Error ( " Enter the 6-digit code from your email. " ); return code ; } Every OTP tutorial uses \d{6} . Every code demo shows six digits. So I typed six digits into the test and it passed. In dev I was generating my own codes and never actually reading the email. Supabase's GoTrue emits an eight-digit code on this project. ^\d{6}$ rejects eight digits outright. The user's perfectly valid credential got thrown out by my own front door with a lie for an error message — "enter the 6-digit code" when the email plainly showed eight. Why it happens: OTP length is a setting, not a constant The length of a GoTrue email OTP is configurable — GOTRUE_MAILER_OTP_LENGTH (Dashboard → Authentication → Email). It defaults to six in many setups and to eight in others depending on when and how the project was provisioned. The number in the tutorial is that author's project setting , not a property of OTPs. Hardcoding 6 couples your client to a server config you don't control and might change. Bump the length for security later and every client silently starts rejecting valid codes. No error in your logs — the rejection