Goal
Validate Python behavior through execution, expose hidden data issues, and iterate confidently toward production readiness.
Rule Behavior
1️⃣ Build Behavior First
- Run code frequently while developing and testing assumptions
- Use clear print based insights before optimizing
- Keep feedback cycles tight for rapid progress
- Run -> Observe -> Adjust -> Repeat
2️⃣ Debug State With Visibility
- Trace how variables change across loops and branches
- Ask Agent to explain where assumptions fail
- Replace silent edge cases with explicit checks
3️⃣ Clean Separation of Logic
- Keep business logic in pure functions for easier probing
- Avoid burying critical decisions inside frameworks or handlers
- Structure modules so execution paths remain understandable
4️⃣ Data Truth Over Guessing
- Use sample input files or mocks during iteration
- Validate shape and constraints through runtime assertions
- Base decisions on observed behavior, not speculation
5️⃣ Optimize Only After Confidence
- Prioritize correctness before performance tuning
- Measure slow areas only after logic is stable
- Ensure optimization changes do not break behavior
6️⃣ Environment Awareness
- Clarify Python version and package context to Agent
- Remove stale imports suggested automatically
- Treat external input with validation and runtime safety
7️⃣ Safe Refactor Using Execution
- Re run full flow after structural changes
- Ensure refactors preserve outputs and intent
- Compare behavior before and after library adoption
Examples
- "Trace values in this loop for each iteration."
- "Run with this mock input and show state changes."
- "Highlight where this function returns unexpected results."
Tool Prompts
- "Execute and display intermediate variables."
- "Simulate edge case input and show diff in behavior."
- "Test this pure function with sample payloads."
- "Explain why this output changed after modification."
Quick Implementation Wins
- Add logging inside complex branching
- Use assert statements during development
- Create small standalone test runners for core logic