Baseline Grid Overlay
Check vertical rhythm against a real baseline grid instead of judging it by eye.
What it adds
A configurable baseline and column grid drawn over the interface for typography and vertical-rhythm review.
What your agent is told to do
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What your agent is told to do
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Derive the default baseline interval from the app's existing type scale and line heights rather than picking a round number, so the grid describes the system the app already claims to follow.
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Let the reviewer change the interval, offset, colour, and opacity from the tool itself, and remember the last settings, because a grid that has to be reconfigured on every reload does not get used twice.
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Anchor the grid to the document origin and keep it registered to the content as the page scrolls, so a heading four screens down can be checked against the same rhythm as the first one.
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Offer a column grid alongside the baseline, matched to the app's real container widths and gutters, and let each be toggled independently.
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Do not treat this as a linter. This feature owns drawing the reference; deciding that an element is off-grid and reporting it as a defect belongs to UI Lint Rules, and measuring the actual gap between two boxes belongs to Spacing Overlay.
Edge cases it handles
7
Edge cases it handles
7- Browser zoom and fractional device pixel ratios make hairlines drift or disappear; recompute line positions from the real rendered scale rather than assuming one CSS pixel equals one device pixel.
- If the app supports more than one density or compact mode, the baseline interval changes with it — the overlay must follow the active mode rather than always drawing the comfortable-mode grid.
- The grid must stay fixed to the content, not to the viewport, or every scroll appears to shift the rhythm and the review is worthless.
- Some elements are deliberately off-grid for optical reasons — icon alignment, cap-height corrections, badges. Provide a way to mark and remember those exceptions so they stop being re-reported at every review.
- Baselines sit at the text baseline, not the top of the line box; aligning the grid to line-box tops will make correctly set type look wrong.
- The overlay must sit above the interface but below modals and toasts, or it becomes impossible to review a dialog against the grid.
- The grid must be absent from production builds, and its toggle must not be reachable by a signed-in customer who guesses a URL parameter.
Definition of done
9
Definition of done
9- A baseline grid can be toggled on any screen, with configurable interval, offset, and opacity.
- Grid settings persist between reloads.
- Lines remain crisp and correctly spaced at every zoom level and device pixel ratio.
- The grid follows the active density mode's baseline interval.
- The grid stays registered to the content while scrolling rather than to the viewport.
- Deliberate optical exceptions can be marked and are not re-flagged.
- The overlay is unavailable in production builds.
- The feature matches the existing design system.
- No existing functionality is broken.
Related features
SEO Setup
SEO Setup
Make your app findable — titles, meta, Open Graph, sitemap, robots.
What it does
The baseline SEO and social-preview setup every public app should have, and most skip.
How it works
- 1 Give every public page a unique, descriptive title and meta description. Find the app's layout and add a mechanism for each page to set them.
- 2 Add Open Graph and Twitter Card tags so shared links render a preview instead of a bare URL.
- 3 Generate a sitemap.xml covering every public, indexable page, and a robots.txt pointing at it.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/seo-setup
Design Token Linter
Design Token Linter
Find the hardcoded colours, spacings, and radii that drifted away from the token set.
What it does
A check over the app's styles and markup that reports raw colour, spacing, typography, radius, and shadow values where an approved token exists.
How it works
- 1 Read the app's existing token definitions as the source of truth for the check, so adding a token to the design system automatically widens what the linter recognises without a second list to maintain.
- 2 Scan every place a value can be written: stylesheets, style objects, inline style attributes, utility class strings, and component props that take a raw value.
- 3 Report the nearest matching token alongside each finding, with the difference, so a developer sees that a 15px gap is one pixel from an existing step and can decide rather than re-derive.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/design-token-linter
Multi-Model Routing
Multi-Model Routing
Send each AI request to the right model using rules you can read and test.
What it does
A deterministic routing layer that picks a model per request from task type, context size, latency budget, and data sensitivity.
How it works
- 1 Express routing as explicit, ordered rules over inputs the app can measure: task type, estimated context size, latency budget, and the sensitivity classification of the data involved. A rule set that can be read line by line can be reviewed and tested.
- 2 Make routing deterministic. The same inputs must always produce the same route, so a bad output can be reproduced and a rule change can be evaluated. Randomised or load-based selection turns every incident into guesswork.
- 3 Classify data before routing and refuse to route restricted content to any destination not approved for it. This check is a hard block, not a preference, and it must run before the request is assembled.
Copy the prompt
No account needed
Add this feature to my app:
https://addthisfeature.com/x/multi-model-routing
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.