bug-fix

bug-fix is a skill for Claude Code, Codex from nexus-substrate/nexus-agents. It costs 41 tokens per session (1,272 once invoked), scanned A, original, MIT.

A bug-fixing procedure for reproducing a defect, finding its root cause, adding a regression test, and rerunning the checks.

In plain words
What is it for?
Use it when debugging or resolving a reported bug, failed test, build failure, or lint failure according to project contribution standards.
Why use it?
It prevents repeated retries and speculative edits from hiding the original failure or creating further problems.

Skill for Claude CodeCodex

Part of the nexus-agents plugin — 33 skills, 16 agents, 1 hook 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/nexus-substrate/nexus-agents/bug-fix
Any agent
npx skills add nexus-substrate/nexus-agents --skill bug-fix
Clone the repo
git clone --depth 1 https://github.com/nexus-substrate/nexus-agents

Made for: Claude Code, Codex.

Or install nexus-agents, the plugin that ships this one along with the rest of its 33 skills, 16 agents, 1 hook.

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 bug-fix

README.md
[![agentmods](https://agentmods.dev/badge/skills/nexus-substrate/nexus-agents/bug-fix.svg)](https://agentmods.dev/skills/nexus-substrate/nexus-agents/bug-fix)
Your own site
<a href="https://agentmods.dev/skills/nexus-substrate/nexus-agents/bug-fix"><img src="https://agentmods.dev/badge/skills/nexus-substrate/nexus-agents/bug-fix.svg" alt="Measured on agentmods" height="20"></a>
Per session 41 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,272 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 $0.00041 $0.01272
Opus 5 $0.00020 $0.00636
Sonnet 5 $0.00008 $0.00254
Haiku 4.5 $0.00004 $0.00127

Measured 5d ago against content hash b6d00d14470a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

bug-fix 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 5d 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.

skills/bug-fix/SKILL.md · 116 lines

How it starts

The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Bug Fix Skill

Full workflow: CONTRIBUTION_GUIDE.md

Stop-the-Line Protocol

When a test, build, or lint fails mid-flow — before making any more changes:

  1. STOP — do not edit, do not retry, do not "just try one more thing"
  2. PRESERVE — capture the raw error, stack trace, last passing commit, and repro command. Paste into the PR description if relevant
  3. DIAGNOSE — run the Triage Sequence below; identify the causal layer, not the first surface that surfaced the error
  4. FIX — change the root cause only. No speculative refactors, no drive-by cleanups
  5. GUARD — add a regression test that would have caught the original failure
  6. RESUME — re-run the full check suite; only then continue the original task

Rationale: failures compound. A bug unresolved at step N makes every change N+1…N+k incorrect. We observed this in #1871 (consensus_vote silent hang) — the symptoms looked like adapter timeouts, the cause was missing overall-deadline race.

Triage Sequence

Run this order before "Implement fix." Skipping steps produces symptom-level patches that regress.

  1. Reproduce reliably. If non-reproducible: log timestamps, add artificial delays to widen race windows, diff CI vs local env. Document the conditions.
  2. Localize to a layer: UI / service / data / build / external dep. Resist "it must be X" — verify with a log, not a hunch.
  3. Reduce to the minimal failing case. Smaller repros make the cause obvious; large repros hide it.
  4. Fix the root cause. If your fix is upstream of where the error surfaced, you're probably right. If it's downstream (dedupe in the view, catch in the caller), you're probably patching the symptom.
  5. Guard with a regression test that fails without the fix.
  6. Verify end-to-end: pnpm lint && pnpm typecheck && pnpm test plus any integration/smoke test for the affected area.

Read the full file on GitHub · 116 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. 5d ago First seen · 116 lines · 41 tokens per session scan A b6d00d14470a

Subscribe to this mod's changes

bug-fix is a skill published in the GitHub repository nexus-substrate/nexus-agents (18 stars, last pushed today), licensed MIT. It adds 41 tokens to every session and 1,272 once invoked, about $0.0002 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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