Overlay Coordination Layer
Give every menu, dialog, and drawer one set of rules for stacking, focus, and dismissal.
What it adds
A single layer owning stacking order, focus handling, background inertness, scroll locking, and dismissal for all floating surfaces.
What your agent is told to do
5
What your agent is told to do
5-
1
Inventory every floating surface the app already has — menus, popovers, tooltips, dialogs, drawers, backdrops, command palettes — and route each of them through the one layer rather than leaving each component to fend for itself.
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2
Maintain an ordered stack of what is open. The topmost surface owns the Escape key and outside-click dismissal, and both must close exactly one level rather than everything at once.
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Record the element that opened each surface, contain focus while it is open, and return focus to that element on close, including when the surface closes because a route changed.
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4
Treat scroll locking and background inertness as counted resources held by the stack, released only when the last holder closes, so a nested dialog closing does not unlock the page beneath its parent.
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5
Do not let components carry their own stacking constants. Assigning arbitrary depth values per component is exactly how a dropdown ends up behind the dialog that contains it, and the layer exists to remove that decision from every component.
Edge cases it handles
7
Edge cases it handles
7- Nested overlays must work in both directions — a menu opened inside a dialog, and a dialog opened from a menu. Closing the inner one must leave the outer one open, focused, and still locking scroll.
- Escape must be coordinated by the stack. If every open surface listens for it independently, one keystroke closes the tooltip, the menu, and the dialog together and the user loses unsaved work.
- Background content must be marked inert while a surface is open and unmarked exactly on close. Leaving the flag set makes the whole page unreadable to a screen reader; setting it on an ancestor of the overlay hides the overlay itself.
- A component that throws or unmounts while open must not leave the page permanently scroll-locked or focus-trapped. Register cleanup with the layer so an error path still releases the lock.
- A route change, a sign-out, or a session expiry while a surface is open must close the stack cleanly rather than leaving an orphaned backdrop over the new page.
- On mobile, the on-screen keyboard changes the usable height under a drawer or sheet, and dismissal by swipe must not conflict with scrolling the surface's own content.
- Where these surfaces are mounted in the document is owned by the Portal Host Registry brief; this brief decides ordering, focus, and dismissal, and must not also create its own mount points.
Definition of done
9
Definition of done
9- Every floating surface in the app is opened and closed through the one layer.
- Stacking order is derived from the open stack, and no component declares its own depth value.
- Escape and an outside click each dismiss exactly one level of the stack.
- Focus is contained while a surface is open and returned to the opening element on close, including on route change.
- Scroll lock and background inertness are released only when the last open surface closes.
- An error or unmount while a surface is open leaves the page scrollable and focusable.
- Mounting is delegated to the portal host registry rather than reimplemented.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Screen Reader Only Utility
Screen Reader Only Utility
One tested way to add text for assistive technology without it appearing on screen.
What it does
A single visually hidden utility used for labels, instructions, and context that assistive technology needs and sighted users do not.
How it works
- 1 Find every place the app currently hides text from sight — off-screen positioning, zero dimensions, transparent colour, tiny font sizes, aria-label strings duplicating nearby copy — and consolidate them onto one utility.
- 2 Build it by clipping the element to nothing while keeping it rendered and in the accessibility tree: it must occupy no visual space and contribute nothing to layout, yet still be read in document order.
- 3 Provide a second variant that becomes visible when it receives focus, and use it for skip links and any other hidden content that is itself focusable.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/screen-reader-only-utility
Avatar Group
Avatar Group
Show who is involved in a compact space without a pile of broken images.
What it does
A stacked set of member avatars with deterministic ordering, an overflow count, and access to the full list.
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.
- 2 Order the stack deterministically by a stable rule such as role then name, so the same group renders in the same order on every load and every device.
- 3 Cap the number shown and collapse the remainder into a single count that is announced meaningfully, not as a bare number sitting after a row of pictures.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/avatar-group
Progress Indicator System
Progress Indicator System
Tell people how far along the work is, in the same way every time.
What it does
A consistent set of bars, rings, step trackers, and accompanying text for work that takes measurable time.
How it works
- 1 Identify every operation in the app that takes long enough to need feedback — uploads, imports, exports, batch actions, multi-step flows — and decide for each whether its progress is genuinely measurable.
- 2 Use a determinate form only when a real proportion is known. Where the total is unknown, use an indeterminate form and say what is happening in words rather than inventing a percentage.
- 3 Pair every indicator with text that names the operation and its current position, so the information survives for someone who cannot see the graphic.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/progress-indicator-system
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.