Magic Link Sign-In
Sign in from an emailed link instead of remembering a password.
What it adds
Passwordless authentication by email: a short-lived single-use link, purpose-bound tokens, and defined behaviour when the link opens somewhere unexpected.
What your agent is told to do
5
What your agent is told to do
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1
Make links short-lived — minutes, not hours — single-use, and bound to the purpose they were issued for. A sign-in token must not also work as a reset or invite token.
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2
Bind the request to the browser that started it: issue a paired value on the request page and require it, so a link opened on another device follows the handoff path instead of silently signing in.
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Give the same response to every address entered, and never reveal whether an account exists at any step.
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Validate the post-login destination against an allowlist and drop anything external.
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Do not make magic links the only way in for accounts that matter. Email is a single point of failure; keep at least one other method available and say so at sign-up.
Edge cases it handles
6
Edge cases it handles
6- Opening the link on a different device or browser must offer an explicit confirmation step rather than failing or silently authenticating.
- Link scanners in corporate mail systems will hit the URL before the user does — consuming the token on GET breaks sign-in entirely for those users.
- Requesting a second link must invalidate the first, and the emails must be distinguishable so people do not click the stale one.
- A consumed or expired link must show a neutral 'request a new one' screen with no account details.
- Requests must be rate-limited per address and per IP; the endpoint sends email on demand.
- The token must not survive in browser history, referrer headers, or server logs after use.
Definition of done
8
Definition of done
8- Links expire in minutes, are single-use, and are valid only for sign-in.
- A link opened in a different browser requires explicit confirmation.
- Pre-fetching by mail scanners does not consume the token.
- Post-login redirects are allowlisted and never external.
- Responses never disclose whether an address is registered.
- An alternative sign-in method remains available on every account.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
User Roles
User Roles
Not everyone should be able to do everything.
What it does
Role-based permissions, enforced on the server, with a UI that reflects them.
How it works
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1
Define roles and their permissions in ONE place. Scattering
if user.admin?through the codebase is how authorization bugs happen. - 2 Enforce every permission server-side, at the controller or service layer.
- 3 Hide UI the user can't use — but never rely on hiding as the enforcement.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/user-roles
Member Directory
Member Directory
Show who is in the workspace and how to identify them.
What it does
A searchable, read-only roster of workspace members with their role, status, and the profile fields they have chosen to share.
How it works
- 1 Build this as a read view. Inviting members is owned by Team Invitations, changing roles is owned by User Roles, and seat counts are owned by Seat Management — link out to those rather than duplicating their controls here.
- 2 Show each member's display name, avatar, role, and status. Status is not decoration: pending, active, suspended, deactivated, and external guest must be visually distinct and filterable.
- 3 Respect per-field profile visibility. A field the member marked private is not rendered, not returned by the API, and not searchable — hiding it in the template while shipping it in the payload is not privacy.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/member-directory
Account Linking
Account Linking
Let one account sign in several ways without spawning duplicates.
What it does
Attach and detach sign-in methods — password, OAuth providers, SSO — on a single existing account.
How it works
- 1 Model sign-in methods as separate identity records attached to one account, rather than columns on the user.
- 2 Require a fresh re-authentication before any link or unlink. A stale session is enough to read the app; it is not enough to change how the account is entered.
- 3 Refuse to link an identity that is already attached to another account. Explain the conflict and point the user at recovery — do not silently steal the identity or silently create a second account.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/account-linking
How it works
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1
Copy the link
Grab the Markdown instruction URL for this feature.
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2
Give it to your AI
Paste it into Claude Code, Cursor, v0, Lovable — whatever you build with.
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3
It inspects, then implements
Your agent reads your existing app first, then adds the feature to fit it.
Works with your stack
These instructions are written to adapt. They tell the agent to detect your framework, match your existing design system, and reuse what you already have — rather than assuming a particular stack.
Need it tighter than that? Customize the feature and tell it exactly what you're running.