debug

A structured method for finding the cause of a software bug before changing code. It records the exact symptom, studies the system's layers, tests possible causes, and checks the original failure after the fix.

In plain words
What is it for?
Use it when a bug is difficult, spans several parts of an application, or has survived an earlier fix attempt.
Why use it?
It reduces repeated guess-and-check fixes that introduce new problems or fail to address the real cause.

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/me2resh/apexyard/debug
Any agent
npx skills add me2resh/apexyard --skill debug
Clone the repo
git clone --depth 1 https://github.com/me2resh/apexyard

Made for: Claude Code, Codex.

Per session 25 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,425 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00025 $0.04425
Opus 5 $0.00013 $0.02212
Sonnet 5 $0.00005 $0.00885
Haiku 4.5 $0.00003 $0.00443

Measured 2d ago against content hash 2120a32f71df, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

debug scanned grade A with 1 finding 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

The cost of one extra `curl`, one extra `Read`, one extra "what does the server actually return?" — is one minute. The cost of one wrong fix that ships, deploys, blocks the user, and then has to be diagnosed again is hou
.claude/skills/debug/SKILL.md · 286 lines

How it starts

The opening of the file, as written. The whole thing — 286 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/debug — Structured Debug Methodology

Most "stuck" debug sessions look the same: pattern-match on the symptom, propose a fix, ship it, find a different symptom, repeat. Each cycle costs a deploy + a CEO approval + the user's patience. This skill enforces the discipline that prevents the loop:

  1. Capture the symptom precisely — the exact URL, the exact response, the exact step that fails.
  2. Read the architecture before guessing — map every layer the request touches.
  3. Form a hypothesis ladder — 3–5 candidate causes ordered by probability, each with an explicit evidence test.
  4. Gather evidence first, fix second — never ship a fix without a verification step that would have caught the wrong hypothesis.
  5. Verify the fix against the original evidence — re-run the symptom check, not just the unit tests.

The cost of one extra curl, one extra Read, one extra "what does the server actually return?" — is one minute. The cost of one wrong fix that ships, deploys, blocks the user, and then has to be diagnosed again is hours.

When to invoke

Trigger this skill when any of the following is true:

  • A previous fix attempt didn't resolve the symptom
  • The symptom involves multiple layers (CDN, framework, backend, auth, network)
  • Pattern-matching on the symptom produces more than one plausible cause
  • The CEO has had to point out the bug exists more than once

If the cause is genuinely obvious (typo in a string, off-by-one in a loop), don't invoke this — just fix it. The skill is for the cases where you're tempted to guess.

Process

Step 1 — Capture the symptom

Write down, in this exact shape:

URL / endpoint:    <exact URL or command>
Action:            <what the user did>
Expected:          <what should have happened>
Observed:          <what actually happened>
Repro recipe:      <minimal steps that reproduce>
Surface evidence:  <screenshot URL, console output, response headers, logs>

If any field is "I'm not sure" — STOP and gather it before going further. Hypotheses built on a fuzzy symptom are guesses dressed up.

Read the full file on GitHub · 286 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 · 286 lines · 25 tokens per session scan A 2120a32f71df

Subscribe to this mod's changes

debug is a skill published in the GitHub repository me2resh/apexyard (497 stars, last pushed 2d ago), licensed MIT. It adds 25 tokens to every session and 4,425 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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