GitHub Copilot Instructions for Agent: Visual Studio Code Extension Integrating Ollama into GitHub Copilot Chat

Welcome! This document guides you through the recommended workflows, conventions, and tooling when working on the Opilot VS Code extension project. Follow these instructions strictly to ensure consistency, quality, and smooth collaboration.

Before Starting Work

• Create or switch to the correct branch before editing code.
• Branch name format: [type]/[short-title] (e.g., feat/add-ollama-integration).

Project Overview

You are working on the Opilot extension, which integrates Ollama models into GitHub Copilot Chat inside VS Code.

Key Features to Keep in Mind

• Local and cloud Ollama model usage inside Copilot Chat.
• Custom Ollama sidebar for model management.
• @ollama chat participant for dedicated conversations.
• Inline code completions using local models.
• Modelfile creation, editing, and building with syntax support.
• Streaming responses and vision model support.
• Local execution for privacy.
• Configuration via VS Code settings.

Development Environment Setup

• Prerequisites:

  • Node.js 20+
  • pnpm (version pinned in package.json)
  • VS Code 1.109.0 or higher
  • GitHub Copilot Chat extension installed
  • Ollama installed locally or remote access configured

• Installing Ollama:

  • Download from https://ollama.ai/download
  • Start Ollama app or run ollama serve
  • Login to Ollama Cloud if using cloud models (ollama login)

• Extension Installation:

  • Install from VS Code Marketplace or .vsix file

Code Quality Standards

This project uses Ultracite, a zero-config preset built on Biome that enforces strict code quality standards through automated formatting and linting. The project has migrated from oxlint/oxfmt to Biome via Ultracite, so check-formatting and format tasks are no longer needed — ultracite check and ultracite fix cover both linting and formatting in a single command.

Quick Reference

• Lint and format code: pnpm dlx ultracite fix
• Check for issues: pnpm dlx ultracite check
• Diagnose setup: pnpm dlx ultracite doctor

Core Principles

Write code that is accessible, performant, type-safe, and maintainable. Focus on clarity and explicit intent over brevity.

Type Safety & Explicitness

• Use explicit types for function parameters and return values when they enhance clarity
• Prefer unknown over any when the type is genuinely unknown
• Use const assertions (as const) for immutable values and literal types
• Leverage TypeScript's type narrowing instead of type assertions
• Use meaningful variable names instead of magic numbers - extract constants with descriptive names

Modern JavaScript/TypeScript

• Use arrow functions for callbacks and short functions
• Prefer for...of loops over .forEach() and indexed for loops
• Use optional chaining (?.) and nullish coalescing (??) for safer property access
• Prefer template literals over string concatenation
• Use destructuring for object and array assignments
• Use const by default, let only when reassignment is needed, never var

Async & Promises

• Always await promises in async functions - don't forget to use the return value
• Use async/await syntax instead of promise chains for better readability
• Handle errors appropriately in async code with try-catch blocks
• Don't use async functions as Promise executors

React & JSX

• Use function components over class components
• Call hooks at the top level only, never conditionally
• Specify all dependencies in hook dependency arrays correctly
• Use the key prop for elements in iterables (prefer unique IDs over array indices)
• Nest children between opening and closing tags instead of passing as props
• Don't define components inside other components
• Use semantic HTML and ARIA attributes for accessibility:
  • Provide meaningful alt text for images
  • Use proper heading hierarchy
  • Add labels for form inputs
  • Include keyboard event handlers alongside mouse events
  • Use semantic elements (<button>, <nav>, etc.) instead of divs with roles

Error Handling & Debugging

• Remove console.log, debugger, and alert statements from production code
• Throw Error objects with descriptive messages, not strings or other values
• Use try-catch blocks meaningfully - don't catch errors just to rethrow them
• Prefer early returns over nested conditionals for error cases

Code Organization

• Keep functions focused and under reasonable cognitive complexity limits
• Extract complex conditions into well-named boolean variables
• Use early returns to reduce nesting
• Prefer simple conditionals over nested ternary operators
• Group related code together and separate concerns

Security

• Add rel="noopener" when using target="_blank" on links
• Avoid dangerouslySetInnerHTML unless absolutely necessary
• Don't use eval() or assign directly to document.cookie
• Validate and sanitize user input

Performance

• Avoid spread syntax in accumulators within loops
• Use top-level regex literals instead of creating them in loops
• Prefer specific imports over namespace imports
• Avoid barrel files (index files that re-export everything)
• Use proper image components (e.g., Next.js <Image>) over <img> tags

Testing

• Write assertions inside it() or test() blocks
• Avoid done callbacks in async tests - use async/await instead
• Don't use .only or .skip in committed code
• Keep test suites reasonably flat - avoid excessive describe nesting

When Biome Can't Help

Biome's linter will catch most issues automatically. Focus your attention on:

1. Business logic correctness - Biome can't validate your algorithms
2. Meaningful naming - Use descriptive names for functions, variables, and types
3. Architecture decisions - Component structure, data flow, and API design
4. Edge cases - Handle boundary conditions and error states
5. User experience - Accessibility, performance, and usability considerations
6. Documentation - Add comments for complex logic, but prefer self-documenting code

Task Execution Using Taskfile

Use the provided Taskfile.yml to run common commands. Run tasks with:

task <taskname>

Common tasks

Code Contribution Workflow

1. Create or switch to the correct branch.

2. Run pre-commit tasks before committing:

   task precommit

3. Test your changes thoroughly:
   • Unit tests: task unit-tests
   • Extension tests: task extension-tests
   • Integration tests: task integration-tests

4. Build the extension before release or PR:

   task compile

5. Push your branch and create a pull request.

Extension-Specific Notes

• The extension auto-detects Ollama at http://localhost:11434 by default.
• Use VS Code settings to configure Ollama host, models, and completions.
• For inline code completions, configure ollama.completionModel and toggle ollama.enableInlineCompletions.
• Use the Ollama sidebar for model lifecycle management (pull, run, stop, delete).
• Manage modelfiles with the dedicated Modelfile Manager sidebar.
• Use the command palette commands like Ollama: Build Modelfile to build custom models.
• Leverage streaming support for real-time response in chat.

Debugging and Testing

• Launch the extension in VS Code Extension Development Host with F5.

• Use the provided test suites:

  • Unit tests with Vitest
  • Extension integration tests
  • Integration tests with pulled models
• Coverage target: 85% or higher.

Resources

• Ollama main repo: https://github.com/ollama/ollama
• Ollama Model Library: https://ollama.ai/library
• Ollama API Docs: https://github.com/ollama/ollama/blob/main/docs/api.md
• Ollama Modelfile Docs: https://github.com/ollama/ollama/blob/main/docs/modelfile.md
• VS Code Language Model API: https://code.visualstudio.com/api/references/vscode-api#LanguageModelsAPI

Summary

• Create or switch to a branch before coding.
• Run tasks via the Taskfile for consistency.
• Use Ultracite (Biome) for linting and formatting — ultracite check and ultracite fix handle both.
• Test, lint, and build before pushing changes.
• Follow branch naming conventions.
• Use VS Code settings and extension UI for Ollama integration features.

Happy coding! 🚀