debug_issue

Systematic Debugging (The Iron Law)

Core Principle: NO FIXES WITHOUT ROOT CAUSE INVESTIGATION FIRST. Symptom patching is failure.

Inputs

• Issue Description: What is broken?
• Observed Behavior: What is happening instead?
• Stack Trace/Logs: (Optional) Error output.

Tooling Strategy

• Use grep_search to find error messages in code.
• Use view_file to inspect logic.
• Use run_command to run reproduction scripts.

Workflow

1. Isolation & Symptom Analysis

• Deviation: Clearly define Expected vs Observed.
• Error Messages: Read the ENTIRE stack trace. Do not skim.
• Environment: Dev vs Prod? Recent changes?

2. Reproduction (The MRE)

• Steps: List the exact steps to fail.
• Determinism: Is it 100% consistent or flaky?
• MRE: Create a Minimal Reproducible Example (strip away everything else).

3. Root Cause Investigation (The "Why")

• Trace Data Flow: Follow the bad value backwards. Where did it originate?
• Instrumentation: "Measure, Don't Guess." Add logs at boundaries.
• Hypothesis: Formulate: "I think X fails because Y."

4. Implementation (The Fix)

• The 3-Strike Rule: If you have tried 3 fixes and they failed, STOP.
  • Observation: You likely have an architecture problem, not a bug.
  • Action: Question the fundamental pattern.
• Single Change: Apply ONE fix. Test it.

5. Verification & Regression

• Verify: Does the MRE pass now?
• Regression: Did anything else break? Run enhance_ui or standard tests.

Rationalization Busting

If you catch yourself saying these, STOP and return to Step 1:

• "I'll just try this quickly..."
• "It's probably X..."
• "I don't know why this works but it does."

Advanced Debugging Strategies

• Binary Search: If a long script or a large commit history fails, cut it in half. Test which half fails. Repeat.
• Targeted Instrumentation: Don't just console.log("here"). Log state: console.log({ user: req.user, authHeader: req.headers.authorization }).
• Form Hypotheses & Controlled Experiments: Before changing code, write down what you think is wrong and what single change will prove it.
• Rubber Ducking / Write it Down: Explain the data flow step-by-step out loud (or in the prompt). The assumption gap often reveals itself.