Field State Matrix
Decide once how every field looks and behaves in every state, before screens improvise.
What it adds
A defined and documented set of visual and behavioural states covering every input type in the app.
What your agent is told to do
5
What your agent is told to do
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1
Enumerate the app's input types and cross them against every state they can enter: empty, filled, focused, hovered, invalid, valid, disabled, read-only, loading, and browser-autofilled.
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2
Define disabled and read-only as genuinely different states — a read-only field shows a real value the user may select and copy, a disabled field is inert and excluded from submission.
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3
Define the loading state so the field is visibly busy and not editable, and say what happens to a keystroke that arrives mid-load rather than letting it be silently swallowed.
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4
Specify what happens to user input when the server rejects a submission: the values stay, the field is marked invalid, and the message names the field's own problem.
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5
Do not encode any state in colour alone. Invalid, disabled, and busy each need a second signal — an icon, text, or a border treatment — because a colour-blind user reading a red border sees a border.
Edge cases it handles
7
Edge cases it handles
7- Disabled and read-only are routinely conflated; the difference matters because a read-only value is often the thing the user came to copy, and a disabled field is excluded from the submitted payload.
- A rejected submission must never blank the form. Losing twenty fields of typed input because the server returned a validation error is the single worst failure this matrix exists to prevent.
- A field in the loading state must be non-editable and must show it, because a value typed into a field that is about to be overwritten by a server response is lost without warning.
- The browser's autofill styling overrides the app's background and text colours and must be handled explicitly, or autofilled fields will look broken in the dark theme.
- Every combination that can co-occur needs a defined result — invalid and disabled, filled and read-only, focused and busy — rather than whichever style happens to be declared last.
- State changes must be exposed programmatically as well as visually, so a field that becomes invalid or disabled is reported to assistive technology.
- This entry defines the states; the structure that renders label, description, and error around them belongs to Form Field Shell, and the required marker to Required Field Indicator.
Definition of done
8
Definition of done
8- Every input type has a defined rendering for empty, filled, focused, hovered, invalid, valid, disabled, read-only, loading, and autofilled.
- Disabled and read-only differ visually and behaviourally, and only one of them submits a value.
- A rejected submission returns with the user's input intact and the offending fields marked.
- Loading fields are visibly busy and reject input.
- Autofilled fields respect the app's theme in both light and dark.
- No state is signalled by colour alone, and every state change is exposed to assistive technology.
- 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
Input Group Component
Input Group Component
Join prefixes, suffixes, and buttons to an input so they read as one control.
What it does
A composite control binding an input to adjoining affixes and buttons within a single visual frame.
How it works
- 1 Find the places the app already fakes this — a currency symbol floating beside a number field, a copy button jammed next to a token, a domain suffix drawn as separate text — and rebuild them as one group.
- 2 Draw the focus treatment around the whole group when any child inside it holds focus, so the composite reads as one control rather than a box beside a button.
- 3 Give the group one accessible name from the field's label and describe affixes separately; a currency symbol or a unit must be exposed as description, not as a second label.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/input-group-component
Form Section Pattern
Form Section Pattern
Break long forms into labelled sections people can scan instead of read.
What it does
A section pattern grouping related fields under a heading, a description, and its own actions.
How it works
- 1 Find the forms that have grown past a screenful — settings, profiles, checkout, configuration — and group their fields by the question each group answers, not by the table the columns come from.
- 2 Give each section a heading in the document's heading order and an optional one-line description, so screen reader and keyboard users can jump between sections.
- 3 Allow at most one level of nesting. A section inside a section inside a tab gives the user no orientation and pushes the fields into a narrow gutter.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/form-section-pattern
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.