This skill should be used when the user asks to "debug this", "fix this error", "investigate this bug", "troubleshoot this issue", "find the problem", "something is broken", "this isn't working", "why is this failing", or reports errors/exceptions/bugs. Provides systematic debugging workflow and com

Bug Detective A systematic debugging workflow for investigating and resolving code errors, exceptions, and failures. Provides structured debugging methods and common error pattern recognition. Core Philosophy Debugging is a scientific problem solving process that requires: 1. Understand the problem Clearly define symptoms and expected behavior 2. Gather evidence Collect error messages, logs, stack traces 3. Form hypotheses Infer possible causes based on evidence 4. Verify hypotheses Confirm or eliminate causes through experiments 5. Resolve the issue Apply fixes and verify Debugging Workflow Step 1: Understand the Problem Before starting to debug, clarify the following information: Required information to collect: Complete error message content Exact location of the error (filename and line number) Reproduction steps (how to trigger the error) Expected behavior vs actual behavior Environment info (OS, versions, dependencies) Question template: Step 2: Analyze Error Type Choose a debugging strategy based on error type: Error Type Characteristics Debugging Method Syntax Error Code cannot be parsed Check syntax, bracket matching, quotes Import Error ModuleNotFoundError Check module installation, path config Type Error TypeError Check data types, type conversions Attribute Error AttributeError Check if object attribute exists Key Error KeyError Check if dictionary key exists Index Error IndexError Check list/array index range Null Reference NoneType/NullPointerException Check if variable is None Network Error ConnectionError/Timeout Check network connection, URL, timeout settings Permission Error PermissionError Check file permissions, user permissions Resource Error FileNotFoundError Check if file path exists Step 3: Locate the Problem Source Use the following methods to locate the issue: 1. Binary Search Method Comment out half the code, check if the problem persists Progressively narrow the scope until the problematic code is found 2. Log Tracing Add print/logging statements at key locations Track variable value changes Confirm code execution path 3. Breakpoint Debugging Use debugger breakpoint functionality Step through code execution Inspect variable state 4. Stack Trace Analysis Find the call chain from the stack trace in the error message Determine the direct cause of the error Trace back to the root cause Step 4: Form and Verify Hypotheses Hypothesis framework: Step 5: Apply Fix After fixing, verify: 1. The original error is resolved 2. No new errors have been introduced 3. Related functionality still works correctly 4. Tests added to prevent regression Python Common Error Patterns 1. Indentation Errors 2. Mutable Default Arguments 3. Closure Issues in Loops 4. Modifying a List While Iterating 5. Using is for String Comparison 6. Forgetting to Call super(). init () JavaScript/TypeScript Common Error Patterns 1. this Binding Issues 2. Async Error Handling 3. Object Reference Comparison Bash/Zsh Common Error Patterns 1. Spacing Issues 2. Quoting Issues 3. Unquoted Variables 4. Variable Scope in Loops 5. Array Operations 6. String Comparison 7. Command Failure Continues Execution Common Debugging Commands Python pdb Debugger Node.js Inspector Git Bisect Bash Debugging Preventive Debugging 1. Use Type Checking 2. Input Validation 3. Defensive Programming 4. Logging Debugging Checklist Before Starting [ ] Obtain the complete error message [ ] Record the stack trace of the error [ ] Confirm reproduction steps [ ] Understand expected behavior During Debugging [ ] Check recent code changes [ ] Use binary search to locate the issue [ ] Add logs to trace variables [ ] Verify hypotheses After Resolution [ ] Confirm the original error is fixed [ ] Test related functionality [ ] Add tests to prevent regression [ ] Document the problem and solution Additional Resources Reference Files For detailed debugging techniques and patterns: references/python errors.md Python error details references/javascript errors.md JavaScript/TypeScript error details references/shell errors.md Bash/Zsh script error details references/debugging tools.md Debugging tools usage guide references/common patterns.md Common error patterns Example Files Working debugging examples: examples/debugging workflow.py Complete debugging workflow example examples/error handling patterns.py Error handling patterns examples/debugging workflow.sh Shell script debugging example

bug-detective