What is frontend-development?

A set of frontend development rules for Rill web applications, covering Svelte components, shared utilities, state stores, data loading, and generated API clients.

Use it when building or changing Rill's local, admin, or shared frontend code, especially components, Svelte stores, server data queries, and OpenAPI integrations.

It helps teams keep shared components reusable, application state organized, API calls consistent, and loading or error states handled clearly.

frontend-development — Cursor rule by rilldata

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods

npx agentmods add rules/rilldata/rill/frontend-development

Clone the repo

git clone --depth 1 https://github.com/rilldata/rill

Made for: Cursor.

Per session 0 Nothing until a file matches its globs; then the whole rule loads.

When invoked 336 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5	$0.00000	$0.00336
Opus 5	$0.00000	$0.00168
Sonnet 5	$0.00000	$0.00067
Haiku 4.5	$0.00000	$0.00034

Measured yesterday against content hash 472d9879495d, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

frontend-development scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

.cursor/rules/frontend-development.mdc · 75 lines

What it actually says

Frontend Development Guidelines

Technology Stack

Web Applications

web-local: Local Rill application (data modeler)
web-admin: Admin control plane frontend
web-common: Shared components and utilities

Component Architecture

Shared Components (web-common)

Generic, reusable components
No business logic dependencies
Proper TypeScript interfaces
Comprehensive prop validation

Component Guidelines

Keep components small and focused

State Management

Svelte Stores

Use Svelte stores for global state
Keep stores modular and focused
Use derived stores for computed values
Implement proper store subscriptions

Data Fetching

Use @tanstack/svelte-query for server state
Implement proper loading states
Handle errors gracefully
Use optimistic updates where appropriate

API Integration

Client Generation

Use orval for OpenAPI client generation
Standardize the naming convention of the admin service usage. Example: const removeProjectMemberUsergroup = createAdminServiceRemoveProjectMemberUsergroup();
Generate clients in web-common
Use generated types for type safety
Implement proper error handling

API Patterns (TODO)

Implement proper request/response types
Handle authentication and authorization
Use proper error boundaries

Accessibility

ARIA Guidelines

Use proper ARIA labels and roles
Implement keyboard navigation
Ensure proper color contrast
Test with screen readers

Semantic HTML

Implement proper heading hierarchy
Use proper form labels and descriptions

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

yesterday First seen · 75 lines · 0 tokens per session scan A 472d9879495d

Subscribe to this mod's changes

frontend-development is a cursor rule published in the GitHub repository rilldata/rill (2,853 stars, last pushed 3d ago), licensed Apache-2.0. It costs nothing until one of its globs matches a file; then it loads 336 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Backend and APIs Documents Frontend csv dataviz duckdb parquet parquet-tools sveltekit

frontend-development