Difficulty: 6/10Intermediate

PromptDiff

A GitHub Action that diffs the system prompts and agent skill files of two PRs and flags when prompt changes drove the code change. Treats prompts as code with proper versioning and review surfacing.

🎯The Problem

Reddit r/cursor and r/ClaudeAI threads regularly ask 'what changed in my agent today, my code is different now' and nobody has a good answer because prompts live in .cursor/rules, .claude/agents, AGENTS.md, and CLAUDE.md without any tool tracking them as a versioned artifact. Meanwhile a 3-line tweak to a system prompt can cascade into 400 lines of changed application code over a week, with zero traceability.

💡The Solution

GitHub Action that watches prompt and skill files (.claude/**, .cursor/**, AGENTS.md, CLAUDE.md, prompts/**), diffs them on every PR, attributes downstream code changes to specific prompt edits, and posts a 'prompt impact' comment showing 'this PR changed line 14 of CLAUDE.md, here are the 3 PRs in the last 30 days that pattern-match the new instruction.'

👥Target Users

Teams of 3-30 using Claude Code, Cursor, or OpenCode where multiple devs edit shared agent rules and need to know who changed what and why.

📊Difficulty: 6/10 — Intermediate

This is an intermediate micro-SaaS idea suited for builders with some shipping experience. Expect to work with third-party integrations, more complex data models, and nuanced user workflows that require careful planning.

Estimated Timeline

A few months to a solid MVP

Skills Needed

Full-stack development, API integrations, and background job processing