VS Code / IDE extension for pre-PR review

[haasonsaas]

Problem

CodeRabbit launched a VS Code extension in May 2025 and it became their fastest-growing acquisition channel. Pre-PR feedback on staged/unstaged changes — before a PR even exists — is a developer experience that CLI alone cannot match. Sourcery and Bito also have IDE extensions.

DiffScope's CLI already supports git staged and git uncommitted commands, which means the review engine is ready. The gap is the IDE surface.

Proposed Solution

Build a VS Code extension that:

Core Features

1. Review staged changes — Run DiffScope on staged changes, show inline annotations
2. Review uncommitted changes — Full working tree review
3. Inline comment display — Show review findings as VS Code diagnostics (warnings, errors, info)
4. Quick fix actions — When DiffScope suggests a fix, offer it as a VS Code Quick Fix
5. Gutter decorations — Severity indicators in the gutter for reviewed lines

Integration

• Shell out to the diffscope CLI binary (avoid reimplementing in TypeScript)
• Parse JSON output and map to VS Code diagnostic positions
• Support user's .diffscope.yml configuration
• Auto-detect model/adapter from config

Stretch Goals

• Review on save — Automatic review of changed files on save (debounced)
• Cursor / Windsurf support — These use the VS Code extension API
• Status bar — Show review status, last review summary
• Sidebar panel — Full review results browser

Distribution

• VS Code Marketplace
• Open VSX Registry (for Cursor, Codium, etc.)

Competitive Context

• CodeRabbit: VS Code, Cursor, Windsurf — fastest acquisition channel
• Sourcery: VS Code, PyCharm/JetBrains
• Bito: VS Code extension
• GitHub Copilot: Deep VS Code integration (built-in)

Priority

Tier 2 — Strong differentiator. IDE presence is becoming expected for code review tools.