Theme Customizer
Let a customer restyle their own space and watch the change happen as they make it.
What it adds
A settings surface where a customer adjusts colours, typography, spacing and corner radius for their workspace, with a live preview.
What your agent is told to do
5
What your agent is told to do
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Build this on top of the app's existing theme tokens rather than beside them. If the library already includes Semantic Color Tokens, OKLCH Theme Tokens or Theme Surface Map, the customizer edits those token values and nothing else; a second styling path will drift out of sync within a release.
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Group the controls the way a customer thinks: brand colour, text and surfaces, typography, spacing, corners. Keep each group small enough that someone can change one thing and see what moved.
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Show the preview inside the real interface, not a mock swatch panel. If Theme Preview Sandbox exists, render the customizer's preview through it.
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Derive the full palette from one or two brand inputs and let advanced users override individual tokens afterwards. Asking a non-designer to pick fourteen colours produces fourteen bad colours.
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Do not let customer input reach the page as raw style text. Parse every value into a known type, reject anything that is not a valid colour, length or font choice, and never concatenate the input into a style declaration.
Edge cases it handles
8
Edge cases it handles
8- A customer will pick a brand colour that leaves text unreadable on it. Check the contrast of every generated foreground and background pair, and either refuse the combination with a plain explanation or correct the derived foreground automatically. If Colour Contrast Guardrails already exists, call into it rather than re-deriving the maths.
- Both light and dark appearances must come out of a single brand colour. A palette that only works in one mode leaves half the customer's users with white text on white cards.
- The preview must not persist. Changes stay local until the customer confirms, and abandoning the screen or losing the connection leaves the live workspace exactly as it was.
- Reset must work per group as well as globally. A customer who wants their spacing back should not have to throw away the colour work they just finished.
- Injected values must not escape their token. A colour field that accepts a full declaration, a URL, or a closing brace lets one customer alter the layout of a page for everyone in their workspace.
- A font choice that fails to load must fall back to a readable stack without shifting the layout, and the customizer should say the font did not load rather than silently showing something else.
- A theme saved under an older token set must be migrated or discarded on upgrade, never applied partially. Half a theme looks worse than none.
- Custom themes must not override states that carry meaning. Destructive, error and warning treatments stay distinguishable no matter what the customer picks.
Definition of done
9
Definition of done
9- The customizer writes to the app's existing theme tokens and introduces no parallel styling path.
- Changes preview live inside the real interface and are discarded unless the customer confirms.
- A single brand colour produces a coherent light and dark palette.
- Every generated text and surface pair meets the app's contrast minimum, or the combination is refused with an explanation.
- Each control group has its own reset alongside a global reset.
- No customer-supplied value reaches the page as unparsed style text.
- Themes stored against a previous token set are migrated or cleared on upgrade.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
Survey Builder
Survey Builder
Build a multi-question survey, send it out, and read all the answers in one place.
What it does
An authoring tool for multi-question surveys, a respondent flow, and a results view with export.
How it works
- 1 Ship a small, honest set of question types first: single choice, multiple choice, short text, long text, and a rating scale. That covers most real surveys. Defer matrix grids, file uploads, and calculated fields rather than half-building them.
- 2 Render the respondent flow with the app's existing Multi-Step Form and Conditional Form Fields, and reuse Form Field Shell for the inputs, so a survey looks and behaves like every other form in the product.
- 3 Give surveys the app's existing Draft and Publish States. Editing a live survey while responses are arriving is the main way survey data gets corrupted, so publishing must be a deliberate act with a clear boundary.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/survey-builder
Automation Builder
Automation Builder
Let customers wire a trigger, some conditions and an action so routine work runs itself.
What it does
A visual builder where a customer connects a trigger to conditions and actions, plus the runtime that executes it and a log of what happened.
How it works
- 1 Ship a fixed, curated set of triggers, conditions and actions drawn from what the app already does. A general-purpose scripting environment is not the minimum version, and offering one you cannot support is worse than offering ten steps that work.
- 2 Run automations through the app's existing background job system. If Background Job Dashboard or Scheduled Job Monitor exists, automation runs appear there rather than in a separate queue nobody watches.
- 3 Make the run log the centre of the feature, not an afterthought. A customer whose automation did nothing needs to see which run fired, what data entered each step, and where it stopped.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/automation-builder
Alignment Guides and Snapping
Alignment Guides and Snapping
Line elements up exactly while dragging, instead of landing a few pixels off.
What it does
Live guide lines and snapping that align a dragged element to the edges, centres, and spacing of its neighbours.
How it works
- 1 Snap to more than edges. Match left, right, top, bottom, horizontal centre, vertical centre, and equal spacing between three or more elements, and draw a guide for whichever match wins.
- 2 Hold a modifier key to suspend snapping entirely for the duration of a drag, so an author who genuinely wants an element two pixels off the grid can place it.
- 3 Compute the snap threshold in canvas coordinates, not screen pixels, so the pull feels the same at every zoom level. A fixed pixel threshold becomes unusable when zoomed out.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/alignment-guides-and-snapping
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.