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
9
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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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
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Show who is involved in a compact space without a pile of broken images.
What it does
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How it works
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- 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
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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.