Code Editor Field
Edit code, JSON, and config with syntax highlighting instead of a bare textarea.
What it adds
A form field backed by a real code editor: syntax highlighting, a language mode per field, and inline validation that tolerates work in progress.
What your agent is told to do
5
What your agent is told to do
5-
1
Load the editor library lazily, only on views that use it, and render a usable plain textarea until it arrives. It must never block first paint.
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2
Set the language mode per field from what the field actually holds, and validate against that mode.
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3
Report syntax errors as you go, but never block typing or reset the content. Half-written JSON is a normal intermediate state; only submission should be gated.
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4
Preserve the content exactly: tabs versus spaces, trailing whitespace, line endings, and the final newline. An editor that reformats on save destroys diffs.
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5
Offer an explicit escape hatch to the plain textarea, and use it automatically when the fancy editor cannot initialise.
Edge cases it handles
6
Edge cases it handles
6- Screen readers and browser autofill do not cope with syntax-highlighted layers — the fallback textarea must be a real, labelled control.
- Pasting a very large file must not freeze the tab; cap the size, disable highlighting above a threshold, and say so.
- Tab must indent inside the editor but must not trap keyboard users — give them a documented way out.
- Content saved with CRLF line endings must come back the same way unless the app deliberately normalises them.
- A failed save must keep the buffer intact; never clear the editor on error.
- Highlighting themes must follow the app's light and dark themes, not ship their own colours.
Definition of done
8
Definition of done
8- The editor library is lazily loaded and never blocks initial render.
- Each field highlights and validates using its declared language.
- Invalid intermediate content can be typed freely; only submit is blocked.
- Whitespace, tabs, and line endings survive a save-and-reload round trip.
- A labelled plain-textarea fallback exists and is used when the editor fails.
- Editor colours match the app's theme in both light and dark.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Unit Converter
Unit Converter
Let people convert a value between units without leaving the page they are on.
What it does
An inline converter that takes a typed value in one unit and shows the equivalent in another, in place.
How it works
- 1 Start from the units the app actually deals in. A shipping tool needs weight and length; a recipe tool needs volume and temperature. Ship those and leave the rest out.
- 2 Convert as the user types, with the result visible beside the input rather than behind a submit button. Let either side be edited so the conversion runs in both directions.
- 3 Reuse the app's existing number parsing and display formatting rather than writing new ones. If Locale-Aware Numbers and Dates or Number Formatting Component is already present, the converter must render through it so grouping and decimal marks match the rest of the app.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/unit-converter
Voice Dictation
Voice Dictation
Put a microphone in text fields so people can speak their input instead of typing it.
What it does
A dictation control on the app's longer text inputs that transcribes speech into the field as the user talks.
How it works
- 1 Add the control to the fields where typing is genuinely tedious: long descriptions, notes, comments, and message bodies. A microphone on a postcode field is clutter.
- 2 Show interim results in the field as they arrive, visually distinct from committed text, so the speaker can see it is working and correct course before they finish.
- 3 Reuse the app's existing Voice Transcription for the server-side path so one recognition configuration and one set of language settings serve both dictation and recorded audio.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/voice-dictation
Form Field Shell
Form Field Shell
Wrap every input in one structure so labels, help, and errors behave the same everywhere.
What it does
A single wrapper owning the label, description, error, and status region around any control in the app.
How it works
- 1 Inventory the app's existing fields and find the variations that have accumulated — label above versus beside, error under versus in a tooltip — then route all of them through one shell.
- 2 Generate a stable identifier per field and use it to link the control to its label, its description, and its error, so the association survives re-renders and does not collide when the same field appears twice on a page.
- 3 Support required, optional, read-only, and disabled as declared states of the shell, and let the shell pass them to the control rather than each screen setting them by hand.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/form-field-shell
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.