debugger

debugger is a skill for Claude Code, Codex from claude-world/director-mode-lite. It costs 56 tokens per session (887 once invoked), scanned A, original, MIT.

A structured method for finding the root cause of software errors and unexpected behavior. It moves from capturing and isolating the problem through testing possible causes, applying a fix, and verifying the result.

In plain words
What is it for?
Use it for exceptions, failed tests, bugs, incorrect results, and other problems that need reproduction, investigation, and verification.
Why use it?
It prevents guesswork by separating the observed failure from possible explanations and checking each explanation against evidence.

Skill for Claude CodeCodex

Part of the director-mode-lite plugin — 36 skills, 14 agents shipped together

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/claude-world/director-mode-lite/debugger
Any agent
npx skills add claude-world/director-mode-lite --skill debugger
Clone the repo
git clone --depth 1 https://github.com/claude-world/director-mode-lite

Made for: Claude Code, Codex.

Or install director-mode-lite, the plugin that ships this one along with the rest of its 36 skills, 14 agents.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for debugger

README.md
[![agentmods](https://agentmods.dev/badge/skills/claude-world/director-mode-lite/debugger.svg)](https://agentmods.dev/skills/claude-world/director-mode-lite/debugger)
Your own site
<a href="https://agentmods.dev/skills/claude-world/director-mode-lite/debugger"><img src="https://agentmods.dev/badge/skills/claude-world/director-mode-lite/debugger.svg" alt="Measured on agentmods" height="20"></a>
Per session 56 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 887 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 $0.00056 $0.00887
Opus 5 $0.00028 $0.00443
Sonnet 5 $0.00011 $0.00177
Haiku 4.5 $0.00006 $0.00089

Measured today against content hash 09f3f50a8faf, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

debugger 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 today.

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.

skills/debugger/SKILL.md · 119 lines

How it starts

The opening of the file, as written. The whole thing — 119 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debugger Skill

Director Mode Lite - Debugging Specialist


5-Step Root-Cause Method

1. CAPTURE      → Collect the full error, reproduce, define expected vs actual
2. ISOLATE      → Narrow to the smallest failing case
3. HYPOTHESIZE  → List and rank likely causes
4. INVESTIGATE  → Test hypotheses, inspect state
5. FIX & VERIFY → Apply the minimal fix, confirm, prevent recurrence

Step 1: Capture

  • Collect the complete error message and stack trace
  • Can reproduce the issue with clear steps
  • Identify the input that triggered the error
  • Know expected vs actual behavior

Step 2: Isolate

  • Identify the failure location from the stack trace
  • Which file(s) and function(s) are involved?
  • When did it start? (git bisect, git log)
  • Narrow down to the smallest reproducible case

Step 3: Hypothesize

  • List possible causes based on evidence
  • Rank hypotheses by likelihood
  • Design a test to confirm or eliminate each

Step 4: Investigate

  • Analyze error messages and logs carefully
  • Add strategic debug logging; inspect variable state at key points
  • Check for: null/undefined values, type mismatches, race conditions, resource exhaustion, external service failures

Common Bug Patterns

Pattern Signs Common Fix
Null/Undefined Cannot read property of undefined Add null checks / optional chaining
Off-by-one Loop runs one too many/few times Check loop bounds
Race condition Intermittent failures Add synchronization
Type coercion "1" + 1 = "11" Explicit type conversion
Async issues Promise { <pending> } Await/handle promises

By language and domain:

  • JavaScript/TypeScript: undefined is not a function (binding), Cannot read property of null (optional chaining), promise rejections (async/await handling), type errors (strict mode)
  • Python: AttributeError (init/typos), TypeError (type validation), ImportError (paths, circular imports), KeyError (dict defaults)
  • Database: connection timeouts (pool exhaustion), constraint violations (validation, foreign keys), deadlocks (transaction ordering)
  • API/Network: 4xx (request validation, auth), 5xx (server-side, resource limits), timeouts (network, long-running queries)

Read the full file on GitHub · 119 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. today Changed · -6 lines 09f3f50a8faf
  2. 5d ago First seen · 125 lines · 56 tokens per session scan A 0eea01f7be8a

Subscribe to this mod's changes

debugger is a skill published in the GitHub repository claude-world/director-mode-lite (81 stars, last pushed 4d ago), licensed MIT. It adds 56 tokens to every session and 887 once invoked, about $0.0003 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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