Form Field Shell
Wrap every input in one structure so labels, help, and errors behave the same everywhere.
What it adds
A single wrapper owning the label, description, error, and status region around any control in the app.
What your agent is told to do
5
What your agent is told to do
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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.
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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.
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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.
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Accept custom controls — comboboxes, date pickers, rich text, file drops — not only native inputs, by letting the shell hand its identifiers to whatever renders inside it.
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Do not have the shell announce the error and also leave the control announcing its own. One error, one announcement; duplicated messages make a screen reader read the same sentence twice.
Edge cases it handles
7
Edge cases it handles
7- Identifiers must be stable across renders and unique across the page — a field repeated inside a repeating group must not point two controls at one label.
- Required, optional, read-only, and disabled are four different things and must be visually and programmatically distinct; a read-only field is still readable and copyable, a disabled one is not.
- An error announced by both the shell's live region and the control's own validation message is read twice; decide which one speaks and silence the other.
- A custom control that renders no native input still needs the label association, the error link, and a focusable element, or the shell will describe something the user cannot reach.
- Help text and error text must both be linked to the control, and when an error appears the description must not be dropped from the association — the user still needs the format rule.
- A field whose label is visually hidden by design still requires an accessible name; no field may rely on placeholder text as its label.
- The wording, placement, and conditional behaviour of the description are owned by Help Text Pattern, and the required marker is owned by Required Field Indicator — this shell owns the slots and the wiring, not the copy.
Definition of done
8
Definition of done
8- Every input in the app renders inside the same shell.
- Each control is programmatically linked to its label, its description, and its error.
- Required, optional, read-only, and disabled render distinctly and are exposed to assistive technology.
- Custom controls use the shell with the same associations as native inputs.
- An error is announced exactly once.
- Repeating a field within a page produces no duplicate identifiers.
- 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
Field State Matrix
Field State Matrix
Decide once how every field looks and behaves in every state, before screens improvise.
What it does
A defined and documented set of visual and behavioural states covering every input type in the app.
How it works
- 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.
- 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.
- 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.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/field-state-matrix
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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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.