Locale-Aware Numbers and Dates
Show and read dates, numbers, and money the way each user writes them.
What it adds
A shared formatting and parsing layer so numbers, currency, percentages, dates, and times render and are read correctly per locale and time zone.
What your agent is told to do
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What your agent is told to do
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Find every place the app formats a number, currency, percentage, date, or time, and route them through one shared helper instead of scattered format strings.
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Store and transmit locale-neutral values: ISO 8601 timestamps in UTC, and numbers as numbers. Format only at the point of display.
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Format currency with the currency's own decimal rules and the locale's symbol placement — some currencies have no decimal places and some put the symbol after the amount.
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Parse user input against the active locale so that typing 1.000,50 is read as one thousand and a half, and reject ambiguous input with a clear message rather than guessing.
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Render dates and times in the user's stored time zone, and show the zone anywhere a time is actionable such as a meeting or a deadline.
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Do NOT use a bare numeric date format like 03/04/2026 anywhere it matters. It reads as two different days on two continents; use an abbreviated month name instead.
Edge cases it handles
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Edge cases it handles
7- Do not assume the browser time zone is the user's — a traveller's laptop lies. Store an explicit preference and let them change it.
- Daylight saving transitions mean a day is not always 24 hours; date arithmetic done in UTC and displayed locally will drift by an hour twice a year.
- Relative times such as 'in 3 hours' go stale on a page left open; refresh them or use an absolute time in tooltips.
- Never do money arithmetic in floating point. Work in minor units and format at the end.
- Right-to-left locales still render digits left to right; do not manually reverse numeric strings.
- A number input on mobile shows a keypad matching the browser locale, which may not match the app's active locale — accept both separators where it is unambiguous.
- Sorting and grouping by date must use the user's time zone, or rows land in the wrong day bucket near midnight.
Definition of done
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Definition of done
9- All display formatting goes through one shared layer.
- Stored and transmitted values are locale-neutral, UTC where applicable.
- Currency respects per-currency decimal rules and per-locale symbol placement.
- Typed input is parsed against the active locale, and ambiguous input is rejected with a clear message.
- Times display in the user's stored time zone, with the zone shown for actionable times.
- No ambiguous all-numeric date format appears in the interface.
- Monetary calculations use minor units, not floats.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Focus Ring System
Focus Ring System
Give every focusable control one clear focus indicator that belongs to the design.
What it does
A single focus treatment applied consistently across buttons, links, inputs, cards, rows, and custom controls.
How it works
- 1 Inventory every focusable element in the app, including the ones made focusable by hand — clickable rows, cards, canvas objects, custom selects — and confirm each shows the shared treatment.
- 2 Distinguish focus arriving from the keyboard from focus arriving from a click, and show the ring for keyboard and programmatic focus. A ring appearing on every mouse press reads as a rendering fault and invites someone to remove it entirely.
- 3 Compose the ring so it stays visible on every surface the control can sit on: page background, card, coloured button, dark toolbar, selected row. A single-colour ring will disappear against at least one of them.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/focus-ring-system
Auto Captions
Auto Captions
Every uploaded video gets timed captions without anyone typing them out.
What it does
An automatic captioning pass over uploaded video that produces a timed caption track shown in the player.
How it works
- 1 Extend the app's existing Voice Transcription rather than adding a second speech pipeline. What is new here is timing, storage as a caption track, and player integration, not the recognition itself.
- 2 Run captioning as a background job triggered after the upload finishes, and reuse the app's existing job progress reporting so the user can see where a long file has got to.
- 3 Store the caption track as its own record linked to the media, with a language, a status, and a source marking it as machine-generated so a human correction can supersede it later.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/auto-captions
Touch Target Checker
Touch Target Checker
Find the controls that are too small or too crowded to hit reliably on a phone.
What it does
A development-time audit reporting the measured hit area and neighbour spacing of every interactive element.
How it works
- 1 Measure the element's actual activation area — the region that responds to a tap — rather than the icon or glyph drawn inside it, since padding and pseudo-element extensions frequently make a small icon a perfectly adequate target.
- 2 Check the gap between adjacent targets as well as their size. Two comfortable buttons sitting flush against each other still produce mis-taps, and the report must say which of the two problems it found.
- 3 Report the offending elements with enough context to locate them — the route, the component, and a way to highlight the element on the page — rather than a count of failures.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/touch-target-checker
How it works
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1
Copy the link
Grab the Markdown instruction URL for this feature.
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Give it to your AI
Paste it into Claude Code, Cursor, v0, Lovable — whatever you build with.
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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.