Rules

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Project Rules vs. Context Rules

• Project Rules - a single, monolithic document in Studio Settings → Project Rules. Always applied in full, not modular, not targeted. Good for the short list of constraints that must absolutely hold on every task regardless of what else is going on: “product images always through the CDN”, “no rounded corners on the brand”, “every user-facing string gets a translation key”.
• Context Rules - individual rule files in the Context Base, each focused on one concern. Modular: review, update, and delete them independently. The rest of this page is about Context Rules - they’re what you edit in Context → Rules and what grows with your project over time.

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How rules fit with the other Context Base types

• Rules apply on every task by default - constraints that hold uniformly, narrowable by surface when a rule should only reach some agents.
• Skills apply when the task touches the domain (or when you force them by name) - domain experts like seo-optimizer kick in whenever relevant.
• Commands apply only when you force them by name - task procedures like code-review, same body shape as a skill but the agent never auto-picks one.
• Guides apply when explicitly referenced - reference documents the agent pulls in on demand.

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What rules are good for

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Writing a rule

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Example: Product images through the CDN

# Product images through the CDN

All product and category imagery must be rendered through our
image CDN, not the raw source URL. This is non-negotiable -
non-CDN images bypass compression, responsive sizing, and cache
warming, and they're what regressed our LCP on the category page
last quarter.

## What to do

- Use the `<FronticImage>` component - it handles CDN URL
  rewriting, `srcset`, and `sizes` for you.
- When the component doesn't fit (rare), build the CDN URL via
  `buildImageUrl(record.image, { width, format: 'auto' })`. Never
  inline the raw source URL.
- Always provide `sizes` alongside `srcset` so the browser picks
  the right variant. The component does this automatically; if
  you're rolling your own, don't skip it.

## What to avoid

- Don't use the raw `record.image.url` in `<img src="…">`. That's
  the source URL, not the CDN URL.
- Don't hardcode a single width ("the 800px version will be fine
  everywhere"). Responsive sizing is the whole point.
- Don't disable lazy loading for below-the-fold images. The
  `<FronticImage>` default is correct.

## Why

Source URLs are uncompressed, unresized, and not cached at the
edge. On category pages with 24 product tiles, that's the
difference between a 1.2s LCP and a 4.8s LCP.

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Example: Use createClient for SDK initialization

# Use createClient for SDK initialization

When adding Frontic Client SDK calls to the frontend, always
initialize via `createClient` with config, not via the default
`import client from './.frontic/generated-client'` path.

Reason: direct imports don't let us configure the proxy URL for
CORS prevention, and we need that for the production build.

Correct:

    import { createClient } from './.frontic/generated-client';
    const client = createClient({ proxyUrl: '/api/frontic' });

Incorrect:

    import client from './.frontic/generated-client';

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Rules are project-wide

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Targeting a rule by surface

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Reviewing and pruning rules

• Is this still true? If the codebase no longer follows it, decide: update the rule, or delete it.
• Does this still matter? A rule that’s technically correct but irrelevant to the work people are actively doing is noise.
• Is this still the right granularity? Rules that accumulated into multi-concern walls of text should be split.

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Rules agents can’t follow perfectly

• Vague rules get vague compliance. A rule that says “write clean code” is meaningless. A rule that says “prefer early returns over nested conditionals” is actionable.
• Contradictory rules produce arbitrary behavior. If Rule A says “always use arrow functions” and Rule B says “always export named functions”, the agent picks one. Review your rules for contradictions when you add new ones.
• Rules that require information the agent doesn’t have get skipped. If a rule says “always tag blocks with the owner team”, the agent needs to know what the owner team is. Put the information in the rule or the agent can’t apply it.

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