Root Cause Analysis

Delegated investigation: symptom → hypothesis → elimination → root cause → prevention.

Steps

1. Load the outfitter:debugging skill for systematic investigation
2. Apply elimination techniques from this skill's references
3. Document investigation trail using RCA templates
4. Deliver root cause report with prevention recommendations

<when_to_use>

• Diagnosing system failures or unexpected behavior
• Investigating incidents or outages
• Finding the actual cause vs surface symptoms
• Preventing recurrence through understanding
• Post-incident reviews requiring formal documentation

NOT for: known issues with documented fixes, simple configuration errors, routine debugging (use debugging skill directly)

</when_to_use>

<rca_focus>

This skill extends debugging with formal RCA practices:

Use debugging for day-to-day bug fixes. Use find-root-causes for incidents requiring formal investigation and documentation.

</rca_focus>

<elimination_techniques>

Three core techniques for narrowing to root cause:

See elimination-techniques.md for detailed methods and examples.

</elimination_techniques>

Investigation Trail

Log every step for handoff and pattern recognition:

[TIME] STAGE: Action → Result
[10:15] DISCOVERY: Gathered error logs → Found NullPointerException
[10:22] HYPOTHESIS: User object not initialized
[10:28] TEST: Added null check logging → Confirmed user is null

RCA Report Structure

1. Summary — one-sentence root cause
2. Timeline — events leading to incident
3. Impact — what was affected, duration
4. Root Cause — why it happened (not just what)
5. Contributing Factors — conditions that enabled it
6. Prevention — changes to prevent recurrence
7. Detection — how to catch it earlier next time

See documentation-templates.md for full templates.

<common_pitfalls>

See pitfalls.md for detailed resistance patterns and recovery.

</common_pitfalls>

ALWAYS:

• Load debugging skill for systematic investigation methodology
• Use elimination techniques to narrow root cause
• Document investigation trail as you go
• Produce formal RCA report for incidents
• Include prevention recommendations
• Identify contributing factors, not just root cause

NEVER:

• Skip formal documentation for incidents
• Stop at "what happened" without "why"
• Propose fixes without understanding root cause
• Omit prevention recommendations
• Blame individuals (focus on systems)

• elimination-techniques.md — binary search, variable isolation, process of elimination
• pitfalls.md — cognitive biases and resistance patterns
• documentation-templates.md — investigation logs and RCA reports