403 on a non-member request confirms the org exists

Returning 403 for both a nonexistent org and one you're not a member of lets an attacker enumerate real org ids by the response code alone.

This is one of the things Multi-Tenant Auth & RBAC Core already handles. Sign-in, organisations, invites and roles — with one customer's data provably unable to reach another's.

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Is this you?

If a request for an org a user isn't a member of returns 403 (forbidden) while a request for a genuinely nonexistent org id returns 404, the status code itself becomes an oracle: an attacker can enumerate which org ids are real just by watching which ones come back 403 instead of 404, without ever seeing a byte of that org's actual data.

Why this one is easy to get wrong

403 reads as the semantically correct HTTP status for "you don't have permission," and REST conventions generally teach 403-for-forbidden, 404-for-not-found as separate, independent rules -- treating them as one combined decision, specifically to avoid leaking existence, is a security-review-level insight that doesn't fall out of REST convention on its own.

What you get instead

Core decision 18 collapses "org doesn't exist" and "org exists but you're not a member" into the same 404 -- org ids must not be enumerable. 403 is reserved specifically for "you are a member but your role is insufficient for this action," which only fires after membership is already established, so it never leaks whether a non-member's guess was a real org id.

Source: ARCHITECTURE.md core decision 18 — checkable in the pack you receive

How you actually use this

You don’t install a library or wire up an SDK. Your own coding agent builds the code in your project, and you keep it — no runtime dependency on us.

Step 1
Download and unzip
You get a folder: the docs that tell an agent what to build, a starting skeleton, and the test suite that decides when it's done.
Step 2
Open it in Claude Code or Cursor
Point your coding agent at the folder. Nothing to install, no account with us, no API key.
Step 3
Paste one prompt
The pack contains the exact prompt. Paste it as your first message and leave it alone — it works through the build itself, choosing a cheaper or stronger model per task.
Step 4
Run ./verify.sh
One command. It prints a pass or fail for every check. Green means the build is done — the same script we ran to produce the receipt on this page.

Typical build: about 12 minutes of your agent working, mostly unattended. Then you integrate the working module into your app the way you would any code you’d written yourself.

Why you can believe this

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