Enter and Exit Animation Pattern
Animate overlays, menus, and panels in and out without flicker or orphaned elements.
What it adds
A shared lifecycle for anything that appears and disappears, keeping the element present until its exit finishes and returning focus at the correct moment.
What your agent is told to do
5
What your agent is told to do
5-
1
Identify everything in the app that appears and disappears — dialogs, drawers, menus, popovers, toasts, tooltips, expanding rows — and give them all one lifecycle rather than each rolling its own.
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2
Hold the element in the document through its exit and remove it only once the exit has actually completed or been interrupted. Removing it at the moment state changes means the exit never plays.
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3
Move focus into the surface once its entrance is far enough along to be visible, and return it to the element that opened the surface only after the exit is done, so the page does not scroll to a target that is still fading.
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4
Make every sequence interruptible. Reopening something mid-exit should reverse from its current position, and closing during an entrance should not leave the element stranded halfway.
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5
Do not tie removal to a fixed timer that happens to match the duration. Timers drift from the real animation, and any change to the motion tokens silently breaks the element's removal.
Edge cases it handles
7
Edge cases it handles
7- An element removed the instant its state flips will never show its exit; it must stay mounted, and inert to interaction, until the exit resolves.
- Focus handling is the part that most often goes wrong — moving it in too early strands the user on an invisible surface, and returning it too late lets a keystroke land on the page behind.
- Interrupted sequences must reverse from where they are. An element caught between entering and leaving must not jump to either extreme or end up stuck with no state at all.
- Under reduced motion the surface appears and disappears immediately, and the mount and unmount timing must still be correct — the lifecycle does not disappear just because the animation does.
- An element still mid-exit must not be reachable by tab, must not be announced to screen readers, and must not block clicks on what is behind it.
- If the surface is removed for a reason unrelated to the user — a route change, a session expiry, a record being deleted — it must be torn down cleanly rather than left animating against a page that no longer exists.
- Nested surfaces, such as a popover inside a dialog, need a defined order so the inner one finishes leaving before the outer one starts.
Definition of done
9
Definition of done
9- Every appearing and disappearing surface in the app uses the same lifecycle.
- Exit animations play fully; no element is removed before its exit completes.
- Focus enters after the entrance is visible and returns only after the exit finishes.
- Interrupting an entrance or exit reverses from the current position with no jump or stranded element.
- Reduced motion removes the animation while leaving mount and unmount timing correct.
- An exiting element is not focusable, not announced, and does not intercept clicks.
- Route changes and forced closures tear surfaces down without leaving orphaned nodes.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Semantic Color Tokens
Semantic Color Tokens
Name colours by the job they do, so changing a theme is one edit rather than a sweep.
What it does
A vocabulary of role-named colour tokens — surface, text, border, accent, danger, success — that components reference instead of literal values.
How it works
- 1 Inventory every literal colour value in the codebase and group them by the job they are doing rather than by the shade they happen to be. Two different greys used as card backgrounds are one role; the same grey used as a background and as a border is two.
- 2 Define the role names once and map each role to a value per theme. A role may resolve to a light grey in one theme and a near-black in another; what must not change is which components reference it.
- 3 Stop shared components accepting raw colour values. A primitive that takes a hex string as a prop guarantees that some product screen will hardcode a colour the themes never learn about.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/semantic-color-tokens
Motion Token System
Motion Token System
Give the app one shared vocabulary of durations and easing curves instead of ad hoc numbers.
What it does
A named set of durations and easing curves, each tied to a category of motion, replacing the timing values scattered through the app's components.
How it works
- 1 Inventory every duration and easing value currently written into the app and group them by what they do: something entering, something leaving, something being emphasised, and something changing size or position.
- 2 Name a small set of durations — roughly instant, quick, standard, and deliberate — and a small set of curves, then map each motion category to a pairing. Four or five of each is enough for an entire product.
- 3 Give entrances and exits different treatment. Something arriving should decelerate into place; something leaving should accelerate away and take less time, because nobody wants to wait for a dismissal.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/motion-token-system
Responsive Grid Tokens
Responsive Grid Tokens
Express columns, gaps, and spans as shared tokens rather than per-component guesses.
What it does
A token set describing column counts, gutters, and span behaviour at each breakpoint, used by every grid in the app.
How it works
- 1 Find the grids already in the app — card lists, dashboards, form layouts, media galleries — and record how many columns each uses at each size. The reconciled set is normally three or four column counts, not one per screen.
- 2 Define gutters from the spacing scale rather than inventing grid-specific values, so the gap between cards matches the rhythm of everything around them.
- 3 Express spans in tokens tied to the column count, so a component asking for half a row keeps working when the row drops from four columns to two instead of overflowing.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/responsive-grid-tokens
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.