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name: debugging-log-analyser
description: "Parse error logs, stack traces, and crash reports into a structured root cause diagnosis. Use when an application is throwing exceptions, crashing, or producing unexpected errors and you need to understand why and what to fix. Produces a structured diagnosis with error classification, stack trace walkthrough, probable root cause with confidence level, affected code path, a concrete code-level fix suggestion, and ordered next debugging steps."

Debugging Log Analyser Skill

Parses raw error logs, stack traces, and crash reports into a structured diagnosis with probable root cause, affected code path, and specific next steps — no hand-waving.

Required Inputs

Ask for these if not provided:

• The log / stack trace / error output (paste directly or describe the error)
• Language and framework (e.g. Node.js + Express, Python + Django, Java Spring, Go)
• Context (what changed before this started — e.g. recent deploy, config change, increased traffic, new input data; or "nothing changed" is also useful)
• Frequency (one-off / intermittent / consistent / regression after a specific change)
• Environment (local dev / staging / production)
• What they've already tried (if anything)

Output Format

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Debugging Report: [Service/App Name]

1. Error Classification

Error type: [Runtime exception / Build error / Config error / Network error / Memory error / Unknown]
Severity: [Fatal / Critical / Warning / Informational]
Recurrence pattern: [One-off / Intermittent / Consistent / On-startup / Under load]

2. Stack Trace Analysis

Walk the stack frame by frame, starting from the origin:

• Origin frame: [File, line, function where it started]
• Propagation path: [How it travelled through the call stack]
• Crash point: [Where it ultimately threw/panicked/exited]

For each significant frame, note whether it is:

• User code (fixable here)
• Framework/library code (usually a misuse issue)
• System/runtime code (usually a config or environment issue)

3. Root Cause Assessment

Probable root cause: [1–2 sentence plain English statement]
Confidence: [High / Medium / Low — and why]
Alternative causes to rule out: [If confidence is not high]

4. Affected Code Path

Entry point: [Where the triggering call began]
Key function(s) involved: [Specific functions/methods named in the trace]
Data that triggered it: [If inferable from the log — e.g. null value, malformed JSON]

5. Suggested Fix

Provide a concrete, code-level suggestion:

• What to change (the minimal fix)
• Why this fixes the root cause
• Any trade-offs or risks in the fix
• A short code snippet if helpful

6. Next Debugging Steps

If the root cause is uncertain, provide an ordered list of 3–5 specific debugging actions:

1. [Specific thing to check — file, log line, config value]
2. [Specific reproduction step or isolation test]
3. [Specific tool command — e.g. strace, pprof, --verbose, add logging at X]

7. Prevention

One or two concrete things that would prevent this class of error recurring:

• Better input validation at [point]
• Add monitoring/alerting for [condition]
• Test that covers [scenario]

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Quality Checks

• Root cause is specific (not "there might be a null pointer issue")
• At least one concrete code-level fix is suggested
• Next steps are actionable commands, not vague advice
• Suggested fix references the actual language/framework in the input (not a generic fix that could apply to any language)
• Confidence level includes a stated reason (not just "High" or "Low" with no explanation)
• Prevention is proactive (not just "add error handling")

Anti-Patterns

• A vague root cause ("something's null somewhere") instead of the specific line/frame
• A generic fix that could apply to any language, ignoring the actual stack trace
• Restating the error message instead of explaining what it means
• "Add error handling" as prevention, with no specific guardrail
• High/Low confidence with no reason behind it

Usage Examples

• "Why is this crashing?" + [paste log]
• "Can you analyse this stack trace?"
• "I'm getting this error, what does it mean?"
• "Debug this log for me"
• "What's causing this exception?"