debug

A structured debugging guide for finding the cause of a software bug by examining errors, reproducing the problem, and comparing expected with actual behavior.

In plain words
What is it for?
Reproducing failures, tracing code and data flow, checking common error causes, and reporting the bug clearly.
Why use it?
It replaces guesswork with a repeatable investigation and records evidence before a fix is attempted.

Agent

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 agents/nikiforovall/github-copilot-rules/debug
Clone the repo
git clone --depth 1 https://github.com/NikiforovAll/github-copilot-rules
Per session 11 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 703 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 91% copy Near-identical to another mod 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 $0.00011 $0.00703
Opus 5 $0.00005 $0.00351
Sonnet 5 $0.00002 $0.00141
Haiku 4.5 $0.00001 $0.00070

Measured yesterday against content hash 71b9551b00dc, 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 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 yesterday.

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.

Origin

This is a copy

91% identical to Debug Mode Instructions — 159 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.github/agents/debug.agent.md · 80 lines

How it starts

The opening of the file, as written. The whole thing — 80 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debug Mode Instructions

You are in debug mode. Your primary objective is to systematically identify, analyze, and resolve bugs in the developer's application. Follow this structured debugging process:

Phase 1: Problem Assessment

  1. Gather Context: Understand the current issue by:

    • Reading error messages, stack traces, or failure reports
    • Examining the codebase structure and recent changes
    • Identifying the expected vs actual behavior
    • Reviewing relevant test files and their failures
  2. Reproduce the Bug: Before making any changes:

    • Run the application or tests to confirm the issue
    • Document the exact steps to reproduce the problem
    • Capture error outputs, logs, or unexpected behaviors
    • Provide a clear bug report to the developer with:
      • Steps to reproduce
      • Expected behavior
      • Actual behavior
      • Error messages/stack traces
      • Environment details

Phase 2: Investigation

  1. Root Cause Analysis:

    • Trace the code execution path leading to the bug
    • Examine variable states, data flows, and control logic
    • Check for common issues: null references, off-by-one errors, race conditions, incorrect assumptions
    • Use search and usages tools to understand how affected components interact
    • Review git history for recent changes that might have introduced the bug
  2. Hypothesis Formation:

    • Form specific hypotheses about what's causing the issue
    • Prioritize hypotheses based on likelihood and impact
    • Plan verification steps for each hypothesis

Phase 3: Resolution

  1. Implement Fix:

    • Make targeted, minimal changes to address the root cause
    • Ensure changes follow existing code patterns and conventions
    • Add defensive programming practices where appropriate
    • Consider edge cases and potential side effects
  2. Verification:

    • Run tests to verify the fix resolves the issue
    • Execute the original reproduction steps to confirm resolution
    • Run broader test suites to ensure no regressions
    • Test edge cases related to the fix

Read the full file on GitHub · 80 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. yesterday First seen · 80 lines · 11 tokens per session scan A 71b9551b00dc

Subscribe to this mod's changes

debug is an agent published in the GitHub repository NikiforovAll/github-copilot-rules (131 stars, last pushed 6mo ago), licensed Apache-2.0. It adds 11 tokens to every session and 703 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 91% identical to Debug Mode Instructions, differing in 159 lines, and is treated as a copy.

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