Add GitHub Copilot instructions with separate sections for engine, rivetkit, frontend, and website

[Copilot]

Adds .github/COPILOT_INSTRUCTIONS.md to provide repository context for GitHub Copilot coding agent per best practices at https://gh.io/copilot-coding-agent-tips.

The instructions file is organized into separate sections for each major part of the repository to provide context-specific guidance.

Content Structure

Rust Engine Section

• Monorepo architecture - Core engine, workflow engine (gasoline), Pegboard actor orchestration
• Build/test patterns - Cargo workspace commands, test output piping to /tmp/
• Error handling - Custom RivetError derive macros with structured error definitions
• Code conventions - Hard tabs, structured logging with tracing, anyhow Result types, workspace dependencies
• Infrastructure - UniversalDB, ClickHouse, NATS messaging, connection pooling
• Development workflow - Docker template regeneration, lefthook formatting

Rivetkit SDK Packages Section

• TypeScript SDK - Core SDK, React hooks, Next.js integration, Cloudflare Workers adapter, DB utilities with pnpm build commands
• Rust SDK - Client SDK following Rust engine patterns with cargo commands
• Python SDK - Client SDK with type hints, async support, pip/pytest commands, and PEP 8 guidelines

Frontend Section

• React/Vite application - Three dashboard configurations (Inspector, Engine, Cloud)
• Technology stack - React, Vite, TypeScript, Tailwind CSS, Radix UI, Clerk, CodeMirror
• Development guidelines - React best practices, hooks patterns, component structure

Website Section

• Next.js documentation site - SSR/SSG with MDX content
• Technology stack - Next.js, TypeScript, MDX, Tailwind CSS, Giscus
• Content generation - Scripts for navigation, examples, markdown, TypeDoc API docs
• Development guidelines - Minimize "use client" for SEO, server-side rendering best practices

General Guidelines

• Git workflow with Graphite CLI and conventional commits

Path Corrections

Fixed outdated paths in documentation to match actual structure:

• packages/common/error/ → engine/packages/error/
• docker/dev → engine/docker/dev
• docker/template/ → engine/docker/template/

Key Patterns

// Custom error system
#[derive(RivetError, Serialize, Deserialize)]
#[error("api", "rate_limited", "Rate limit exceeded", "Limit: {limit}")]
struct ApiRateLimited {
    limit: u32,
    reset_at: i64,
}

// Structured logging - lowercase verbs, capitalized code symbols
tracing::info!(?user_id, "inserted UserRow");

Original prompt

---

This section details on the original issue you should resolve

<issue_title>✨ Set up Copilot instructions</issue_title>
<issue_description>Configure instructions for this repository as documented in Best practices for Copilot coding agent in your repository.

</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes ✨ Set up Copilot instructions #3644

---

✨ Let Copilot coding agent set things up for you — coding agent works faster and does higher quality work when set up for your repo.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Review	Updated (UTC)
rivetkit-serverless	Error		Dec 12, 2025 10:49pm

3 Skipped Deployments

Project	Deployment	Review	Updated (UTC)
rivet-cloud	Ignored		Dec 12, 2025 10:49pm
rivet-inspector	Ignored	Preview	Dec 12, 2025 10:49pm
rivet-site	Ignored	Preview	Dec 12, 2025 10:49pm

[jog1t]

@copilot create separate rules/summaries/descriptions for:

• rust code, ie. engine
• rivetkit packages,
• frontend
• website

[Copilot]

@copilot create separate rules/summaries/descriptions for:

• rust code, ie. engine
• rivetkit packages,...

Done! The COPILOT_INSTRUCTIONS.md file has been reorganized with separate sections for:

1. Rust Engine - Build commands, error handling, logging patterns, Docker setup
2. Rivetkit SDKs - TypeScript, Rust, and Python client SDK packages with language-specific guidelines
3. Frontend - React/Vite dashboard with technology stack and development patterns
4. Website - Next.js documentation site with content generation and SSR/SSG guidelines

Commit: c13cc0c