Number Formatting Component
Format every count, percentage, and total the same way, without rounding away meaning.
What it adds
One shared path for displaying numeric values, covering precision, abbreviation, locale separators, and the values that are not numbers.
What your agent is told to do
5
What your agent is told to do
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Find every numeric value the app renders — counts, totals, percentages, durations, file sizes, ratios — and give each a declared type so the display rules follow from what the number is rather than from where it appears.
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Set precision per type and never abbreviate a value the user must act on. A summary tile can say 1.2k, but a quantity someone is about to reconcile or pay must show in full.
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Keep the exact value available even where a shortened one is displayed, on hover and to assistive technology, so a rounded figure can always be checked.
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Format separators, decimal marks, and percentage placement from the viewer's locale rather than hardcoding a convention, and align numeric columns on the decimal so magnitudes can be compared down a column.
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Do not sort or filter on the formatted string. An abbreviated or separated value sorts as text, which puts 9 after 1.2k; keep the raw number for every comparison and use the formatted form only for display.
Edge cases it handles
7
Edge cases it handles
7- Rounding must not change what the number means. A 99.6 per cent success rate displayed as 100 per cent hides every failure, so round toward the honest side for values where the difference matters.
- The value used for sorting, filtering, and thresholds must be the raw number, never the rendered string.
- Separators and decimal marks differ by locale — the same characters mean opposite things in different regions — so they must come from the viewer's locale rather than the developer's.
- Null, infinity, not-a-number, and negative zero each need a defined rendering. A missing value shown as 0 is a false statement about the data, and negative zero must display as zero.
- Very large and very small values need a defined ceiling and floor rather than an unbounded string that breaks the column width.
- A percentage must be unambiguous about whether it is already scaled; a ratio of 0.5 rendered as 0.5 per cent is a hundredfold error.
- Dates, times, and durations expressed as timestamps belong to Date and Time Display Component; this component owns quantities only.
Definition of done
9
Definition of done
9- Every numeric display in the app goes through the shared formatting path with a declared value type.
- Precision and abbreviation rules are defined per type and applied consistently.
- Sorting, filtering, and comparison always use the raw value, never the formatted string.
- Separators and decimal marks follow the viewer's locale.
- Null, infinity, not-a-number, and negative zero each render a defined state.
- The exact value is reachable wherever an abbreviated or rounded one is shown.
- Numeric columns align on the decimal point.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Feedback Widget
Feedback Widget
Let anyone report a bug or send a comment from the page they are looking at.
What it does
An always-available launcher that opens a short feedback form and submits it with page context attached.
How it works
- 1 Put a single persistent launcher in one corner of the app and open a compact form in place. Do not route the user to a separate feedback page and lose the context they were about to describe.
- 2 Attach the current URL, the app version, the viewport size, the signed-in account, and a short trail of recent client errors automatically, so the reporter does not have to describe where they were.
- 3 Show the captured context to the user before they send it, in a collapsible section, and let them remove it. Silent collection of screen state is a trust problem.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/feedback-widget
Booking Page
Booking Page
A shareable page where someone picks an open time and confirms it in a few clicks.
What it does
A public scheduling page listing open slots, taking a booking, and confirming it to both sides.
How it works
- 1 Build the visitor path first: pick a date, see open times in their own zone, fill a short form, confirm, and receive an email with the details and a cancellation link. That is the minimum coherent version.
- 2 Derive open slots from the owner's availability rules and existing bookings on the server at request time. Do not trust a slot list the browser has been holding since page load.
- 3 Reuse the app's existing Time Zone-Aware Scheduling for conversion and storage, store every time as an absolute instant, and display it converted to the visitor's detected zone with the zone named on screen.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/booking-page
Audio Chapter Markers
Audio Chapter Markers
Break a long recording into named chapters listeners can see and jump between.
What it does
Named, timestamped chapters on long audio or video, shown in a list and on the scrubber, each addressable by its own link.
How it works
- 1 Store chapters as an ordered list of start times and titles attached to the existing media record, and render them both as a list beside the player and as markers on the scrubber.
- 2 Let an author add, rename, reorder by moving start times, and delete chapters in the player itself, with the current playback position offered as the default start time for a new chapter.
- 3 If chapters are generated automatically, treat the generated set as a first draft. The author's edits must win and must survive the next generation run.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/audio-chapter-markers
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.