Goal
Use Cursor summaries and runtime exploration to understand legacy code quickly, identify risks, and prepare for safe refactors.
Rule Behavior
1️⃣ Start With High Level File Summaries
- Use "Summarize this file" before reading line by line
- Ask for the main responsibilities, inputs, and outputs of the file
- Identify which functions are entry points and which are helpers
2️⃣ Map Dependencies And Call Relationships
- Ask the Agent to list imports, exports, and key dependencies
- Understand which modules this file depends on and who depends on it
- Use summaries to spot tight coupling and shared utilities
3️⃣ Trace Data Flow And Side Effects
- Request an explanation of how important values move through the file
- Identify where state is mutated, where IO happens, and where errors are handled
- Focus on flow that affects users, external systems, or persistence
4️⃣ Highlight Complexity And Risky Areas
- Ask the Agent to point out deeply nested logic, long functions, or duplicated patterns
- Mark sections that are hard to reason about or fragile under change
- Prioritize these areas for refactoring after behavior is understood
5️⃣ Turn Summaries Into Lasting Documentation
- Save the best file summaries as comments, docs, or architecture notes
- Keep a short description of what the module does and how it is used
- Update summaries when behavior changes so they stay trustworthy
Examples
- "Summarize this legacy file and list its main responsibilities."
- "Explain how data flows from the controller to the database in this module."
- "Show which other files depend on this function."
Tool Prompts
- "Summarize this file, including key functions, side effects, and dependencies."
- "Create a high level description of this module for onboarding documentation."
- "Identify risky or complex areas in this file that should be refactored later."
- "List all imports and the main exported functions with a one line purpose each."
Quick Implementation Wins
- Summarize the top five most confusing or critical legacy files
- Attach summaries to pull requests that touch legacy areas
- Use summaries to guide where to add tests before refactoring