Image Lightbox
Open images at a useful size without sending users to a raw file URL.
What it adds
An overlay viewer that shows an image at full size with zoom, keyboard control, and a clean way out.
What your agent is told to do
6
What your agent is told to do
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1
Open the viewer as a modal layer with focus trapped inside it, and return focus to the thumbnail that opened it on close.
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2
Support Escape, a visible close button, a click on the backdrop, and the browser back button. Back must close the viewer rather than leaving the page.
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3
Show the low-resolution thumbnail immediately and swap in the full image when it loads, so the viewer is never a blank rectangle.
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4
Support pinch and double-tap zoom on touch, and keyboard zoom and pan on desktop, with a reset to fit.
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5
Do not load the original file at full resolution on a phone. Request a size appropriate to the viewport and device pixel ratio, or a large photo will exhaust memory and kill the tab.
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6
The surrounding file list, ordering, and captions are owned by Attachment Gallery; this feature is the viewer only.
Edge cases it handles
6
Edge cases it handles
6- A broken, deleted, or still-processing image must show a clear state inside the viewer, not an empty overlay or a browser error icon.
- A private image whose signed URL expires while the viewer is open must re-authorize or fail with an explanation.
- Background scrolling must be locked while open, and restored to the same position on close — including on iOS, where this is not automatic.
- Swipe to dismiss and swipe to pan conflict once zoomed; dismissal must only apply at the default zoom level.
- The image needs its alt text carried into the viewer; a decorative thumbnail becoming a focal image without a description is a regression.
- Very tall or very wide images must fit to the viewport on open rather than opening at native size.
Definition of done
9
Definition of done
9- Focus is trapped while open and restored to the trigger on close.
- Escape, the close button, the backdrop, and browser back all close the viewer.
- A placeholder or thumbnail is visible while the full image loads.
- Zoom works by pinch, double-tap, and keyboard, with a reset to fit.
- Requested image size is bounded by viewport and device pixel ratio.
- Broken, private, and processing images each have their own state.
- Background scroll is locked and restored exactly.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Beautiful Empty States
Beautiful Empty States
Replace blank screens with useful, contextual empty states.
What it does
Every list, table, and dashboard in your app has a "nothing here yet" state. Most
apps ship a blank rectangle — and it is often the very first thing a new user sees.
An empty state should say what belongs here, why it is empty, and what to do next.
How it works
- 1 Inventory the empty cases first. List every collection view in the app and
- 2 Distinguish the three kinds of empty. They are not the same, and must not
- 3 Build one reusable empty-state component from the existing design system,
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/beautiful-empty-states
Countdown Timer
Countdown Timer
A live countdown to a deadline that ends cleanly instead of running negative.
What it does
A countdown component driven by a server-provided deadline, with a defined finished state.
How it works
- 1 Send the deadline and the server's current time together, compute the offset between server and device once, and count against the corrected value. The device clock cannot be trusted to be right.
- 2 Recompute the remaining time from the corrected clock on every tick rather than decrementing a stored number, so a suspended tab does not resume showing a value minutes behind reality.
- 3 Define the finished state explicitly: what the component shows at zero, whether it reveals something, disables a control, or triggers a refetch. Reuse the app's existing Progress Indicator System styling rather than introducing new type and colour for the digits.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/countdown-timer
Expandable Text
Expandable Text
Shorten long text without making the full content hard to reach.
What it does
Long text clamped to a few lines, with an explicit control to show the rest and collapse it again.
How it works
- 1 Clamp by rendered lines, not by character count. Cutting a string at a fixed length breaks words, mangles markup, and truncates differently at every width.
- 2 Only show the expand control when the text is genuinely clipped. A 'Show more' on a two-line paragraph is noise.
- 3 Use a real button with an accessible label naming what expands, and expose the expanded state. An untagged 'more...' is invisible to a screen reader.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/expandable-text
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.