// Applies a modified Fagan Inspection methodology to systematically resolve persistent bugs and complex issues. Use when multiple previous fix or debugging attempts have failed repeatedly,or when a methodical root cause analysis or complex problems is needed. Do not use for simple troubleshooting.
| name | systematic-debugging |
| description | Applies a modified Fagan Inspection methodology to systematically resolve persistent bugs and complex issues. Use when multiple previous fix or debugging attempts have failed repeatedly,or when a methodical root cause analysis or complex problems is needed. Do not use for simple troubleshooting. |
| model | opus |
This skill applies a modified Fagan Inspection methodology for systematic problem resolution when facing complex problems or stubborn bugs that have resisted multiple fix attempts.
Follow these four phases sequentially. Do not skip phases or attempt fixes before completing the inspection.
Establish a clear understanding of the problem before analysis:
Output: A clear problem statement that anyone could understand.
Perform a line-by-line walkthrough as the "Reader" role in Fagan Inspection. Identify defects without attempting to fix them yet - this is pure inspection.
Check against these defect categories:
Logic Errors
Boundary Conditions
Error Handling
Data Flow Issues
Integration Points
Think aloud during this phase. For each section of code:
Output: A categorised list of identified defects with line numbers and specific descriptions.
After identifying issues, trace back to find the fundamental cause - not just symptoms.
Five Whys Technique:
Consider:
State assumptions explicitly:
Output: A clear statement of the root cause, the chain of reasoning that led to it, and any assumptions that need validation.
Now propose specific fixes for each identified issue.
For each proposed solution:
Verification Planning:
Output: A structured list of fixes with verification steps.
After completing all four phases, provide:
Creates structured development plans with phased task breakdowns, requirements, and QA checklists. Use when the user explicitly asks to create a dev plan, development plan, or document development requirements.
Creating and maintaining CLAUDE.md project memory files and .claude/rules/ rule files that provide non-obvious codebase context. Use when (1) creating a new CLAUDE.md for a project, (2) adding architectural patterns or design decisions to existing CLAUDE.md, (3) capturing project-specific conventions that aren't obvious from code inspection, (4) organising instructions into path-scoped rule files.
Reverse-engineer an application's design system from its codebase and screenshots. Use when asked to analyse visual design, extract a colour palette, document UI patterns, identify typography and spacing systems, audit design consistency, or understand the design language of a frontend codebase.
Delays execution of a task until a specified time or after a duration. Use when the user asks to run something later, in X minutes/hours, at a specific time, schedule a command, or defer work to a future point.
Interview the user relentlessly about a plan or design until reaching shared understanding, resolving each branch of the decision tree. Use when user wants to stress-test a plan, get grilled on their design, or mentions "grill me".
Rewrites text containing AI slop to make it more human-like. Use when explicitly asked to rewrite AI generated text.
