Portal Host Registry
Give floating interface elements a known, ordered place to render outside the layout flow.
What it adds
A registry of named mount points for tooltips, menus, dialogs, and notifications, with a defined order and lifecycle.
What your agent is told to do
5
What your agent is told to do
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Define a small set of named hosts by purpose — one for tooltips, one for menus and popovers, one for dialogs and drawers, one for notifications — and have components ask for a host by name rather than reaching into the document themselves.
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Guarantee exactly one host per name for the lifetime of the application, and make a second registration under the same name a loud failure rather than a silently duplicated mount point.
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Make the first server-rendered pass safe: render nothing, or render inline, until the host exists, then attach. Any code that assumes a document node during the first render will break rendering on the server.
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Mirror theme variables, colour scheme, text direction, and locale onto the hosts, because content mounted outside the application subtree does not inherit anything set on an ancestor inside it.
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Do not implement focus trapping, stacking order, or dismissal here. Those belong to the Overlay Coordination Layer brief; this registry decides only where a surface is mounted and in what document order.
Edge cases it handles
7
Edge cases it handles
7- The first render on the server happens before any host node exists. The component must produce valid output in that pass and attach afterwards, without a mismatch warning or a flash on hydration.
- Content rendered into a host sits outside the application's element tree and loses every inherited style variable, direction, and font setting. Without those mirrored onto the host, a dialog renders in the wrong theme on a page that is otherwise correct.
- Duplicate hosts appear when a module is loaded twice, when a development reload re-registers, or when the app is embedded twice on one page. Each duplicate silently swallows some surfaces and the bug looks intermittent.
- Events crossing a portal follow the component tree in the framework but the document tree natively, so outside-click detection written against native listeners will treat a click inside a menu as a click outside it.
- Unmounting a component must remove its portalled content. A dialog whose owner navigated away, leaving its markup behind in the host, is a stuck overlay with no way to close it.
- Hosts must be ordered in the document so notifications sit above dialogs and tooltips above both, since document order is the tiebreaker whenever stacking values are equal.
- When the app is embedded inside someone else's page, a generically named global host can collide with the host page's own. Scope the host identifiers to the application instance.
Definition of done
9
Definition of done
9- All portalled content mounts into a named host obtained from the registry.
- Exactly one host exists per name, and a duplicate registration fails loudly.
- Server rendering completes without touching a host node and hydrates without mismatch or flash.
- Theme variables, colour scheme, text direction, and locale apply to portalled content identically to inline content.
- Unmounting an owning component removes its content from the host, leaving no orphaned markup.
- Hosts appear in a defined document order that puts notifications above dialogs and tooltips above both.
- Focus, stacking, and dismissal behaviour is delegated to the overlay coordination layer.
- The feature matches the existing design system.
- No existing functionality is broken.
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How it works
- 1 Find the places that show several people at once — assignees, collaborators, workspace members, comment participants — and render them through one grouped component.
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No account needed
Add this feature to my app:
https://addthisfeature.com/x/avatar-group
Stepper Component
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What it does
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How it works
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No account needed
Add this feature to my app:
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Dropdown Menu Primitive
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What it does
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How it works
- 1 Find every action menu in the app — row overflow menus, account menus, bulk-action menus, toolbar menus — and rebuild them on one primitive so they stop behaving differently from each other.
- 2 Implement the full keyboard model: arrows move between items, Home and End jump to the ends, typing letters jumps to the matching item, Enter and Space activate, and Escape closes and returns focus to the trigger.
- 3 Close on outside pointer press, on Escape, and on the trigger being pressed again, and always return focus to the trigger so the user is not dropped at the top of the document.
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No account needed
Add this feature to my app:
https://addthisfeature.com/x/dropdown-menu-primitive
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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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.