Popover Positioning Engine
Place anchored panels where the user expects them and never off the edge of the screen.
What it adds
A single positioning layer that places any anchored element relative to its trigger and keeps it inside the viewport.
What your agent is told to do
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What your agent is told to do
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Find everything the app anchors to a trigger — menus, tooltips, date pickers, select lists, autocomplete panels, colour pickers — and move them all onto one positioning layer rather than leaving each with its own offset arithmetic.
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Express placement as a preferred side and alignment, then let the engine flip to the opposite side, slide along the anchor, or reduce the panel's available height when the preferred placement does not fit.
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Recompute position when the anchor moves for any reason: page scroll, scroll inside a container, window resize, content changing size, or the anchor itself being repositioned.
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Measure against the real rendered geometry rather than assumed offsets, so panels stay correct under browser zoom, page-level scaling, and ancestors with transforms applied.
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Do not position by absolute coordinates measured once at open. The first frame will be right and every subsequent scroll will leave the panel stranded away from its trigger.
Edge cases it handles
7
Edge cases it handles
7- When the preferred side has insufficient room, the engine must flip to the opposite side, shift along the cross axis to stay in view, or constrain the panel's height and let it scroll internally — and it must pick one deterministically rather than oscillating between two placements.
- An anchor inside a scrolling container moves independently of the page. Track that container's scrolling too, and hide or detach the panel when the anchor scrolls out of sight rather than leaving it floating over unrelated content.
- Browser zoom, transformed ancestors, and fractional device pixel ratios all break naive coordinate arithmetic and leave the panel a few pixels adrift or badly misplaced. Measure real geometry at position time.
- A pointer arrow must be repositioned along with the panel after any flip or shift, and clamped so it still touches the anchor and never overhangs the panel's own rounded corner.
- Two anchored panels open at once need a defined stacking order, so a menu opened from inside a dialog renders above it rather than behind.
- A panel wider than the viewport on a small screen must not simply be pushed inward until it covers its own trigger; below a defined width, fall back to a full-width sheet.
- Position must be settled before the panel becomes visible, or the user sees it appear in the wrong place and slide into position.
Definition of done
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Definition of done
9- Every anchored surface in the app is positioned by the same engine.
- No anchored panel is ever clipped by or extends beyond the viewport edge.
- Panels follow their anchor through page scroll, container scroll, and window resize.
- Placement is stable and does not flicker between two sides at a boundary size.
- Arrows remain aligned to the anchor after a flip or shift.
- Positioning is correct under browser zoom and inside transformed ancestors.
- A panel is fully positioned before it is painted, with no visible jump.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
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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
Stepper Component
Stepper Component
Show people where they are in a multi-step flow and what is still ahead of them.
What it does
A single stepper used by every staged flow in the app, showing step order, completion, and errors.
How it works
- 1 Find every staged flow the app already has — onboarding, checkout, import wizards, multi-page settings — and render them all through one stepper rather than the three variants that have grown up separately.
- 2 Keep completion and navigation as two distinct concepts. A step can be complete without being current, and a step the user is allowed to jump back to is not the same as a step they have finished.
- 3 Model optional and skippable steps explicitly, and show a skipped step as skipped rather than as complete or as untouched. A user who skipped payment details needs to see that it is still outstanding.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/stepper-component
Dropdown Menu Primitive
Dropdown Menu Primitive
Give every action menu in the app the same keyboard, pointer, and dismissal behaviour.
What it does
A reusable menu primitive covering triggering, item navigation, selection, disabled items, and closing.
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.
Copy the prompt
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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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.