error-analysis

A structured method for reading error messages, stack traces, and unexpected application behavior before attempting a fix.

In plain words
What is it for?
Use it for compile errors, runtime failures, CI failures, production stack traces, and silent or unexpected behavior.
Why use it?
It helps identify what kind of error occurred and where it began, reducing diagnosis based on guesses.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/jeremydev87/codingbuddy/error-analysis
Any agent
npx skills add JeremyDev87/codingbuddy --skill error-analysis
Clone the repo
git clone --depth 1 https://github.com/JeremyDev87/codingbuddy

Made for: Claude Code, Codex.

Per session 29 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,891 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00029 $0.01891
Opus 5 $0.00015 $0.00945
Sonnet 5 $0.00006 $0.00378
Haiku 4.5 $0.00003 $0.00189

Measured 2d ago against content hash 9bb49134c644, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

error-analysis scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

packages/rules/.ai-rules/skills/error-analysis/SKILL.md · 252 lines

How it starts

The opening of the file, as written. The whole thing — 252 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Error Analysis

Overview

Errors are information. Stack traces are maps. Reading them carefully reveals root cause faster than guessing.

Core principle: Classify the error before diagnosing it. Different error classes have different diagnostic approaches.

Relationship to systematic-debugging: Use error-analysis to understand WHAT the error is and WHERE it originates. Use systematic-debugging to find WHY it happens and implement the fix.

Iron Law:

READ THE ENTIRE STACK TRACE BEFORE FORMING ANY HYPOTHESIS

The answer is almost always in the error message. Most debugging failures are reading failures.

When to Use

  • Encountering a new error message
  • Stack trace from production logs
  • Unexpected application behavior (silent failure)
  • CI/CD pipeline failures
  • Type errors, runtime errors, build errors

Error Classification

First, classify the error type:

Class Symptoms Common Causes
Syntax Error Fails at parse/compile time Typo, missing bracket, wrong syntax
Type Error TypeScript compiler error Wrong type, missing null check
Runtime Error Fails during execution Null reference, division by zero
Logic Error Wrong output, no crash Algorithm mistake, off-by-one
Network Error Connection failures Service down, timeout, firewall
Config Error App won't start Missing env var, wrong path
Concurrency Error Intermittent failures Race condition, deadlock
Memory Error Growing memory, crash Memory leak, large allocation

Reading Stack Traces

Anatomy of a Stack Trace

Error: Cannot read properties of undefined (reading 'name')  ← Error type + message
    at RulesService.getRule (/app/src/rules/rules.service.ts:42:18)  ← Closest to error
    at McpService.handleTool (/app/src/mcp/mcp.service.ts:87:32)
    at McpModule.dispatch (/app/src/mcp/mcp.module.ts:23:12)  ← Furthest from error

Reading order:

  1. Error message — WHAT went wrong
  2. First frame — WHERE it broke (your code closest to error)
  3. Subsequent frames — HOW we got there (call chain)
  4. Last frame — ENTRY POINT that triggered the chain

Read the full file on GitHub · 252 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 252 lines · 29 tokens per session scan A 9bb49134c644

Subscribe to this mod's changes

error-analysis is a skill published in the GitHub repository JeremyDev87/codingbuddy (31 stars, last pushed 4mo ago), licensed MIT. It adds 29 tokens to every session and 1,891 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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