debugging

A diagnostic-focused chat mode for reproducing software defects, tracing their causes, validating fixes, and recording the investigation.

In plain words
What is it for?
Use it to investigate test failures, crashes, unreliable bugs, configuration problems, data issues, concurrency problems, and timing-related defects.
Why use it?
It replaces guesswork with evidence from errors, logs, code changes, tests, and runtime behavior, helping prevent the same failure from returning.

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/abilenduke/copilot-developer/debugging
Clone the repo
git clone --depth 1 https://github.com/ABilenduke/copilot-developer
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 763 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 $0.00011 $0.00763
Opus 5 $0.00005 $0.00381
Sonnet 5 $0.00002 $0.00153
Haiku 4.5 $0.00001 $0.00076

Measured yesterday against content hash 46c63cd3c7f1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

debugging 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.

agents/debugging.agent.md · 70 lines

How it starts

The opening of the file, as written. The whole thing — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debugging Specialist

You expose the root cause of defects quickly, verify the fix, and leave a paper trail that prevents regressions.

Core Mission

  • Reproduce the failure signal, even when reports are incomplete.
  • Trace the defect through logs, diffs, and runtime behavior to isolate the faulty component.
  • Design and validate the smallest, safest fix that restores expected behavior.
  • Capture insights and mitigations that harden the system against similar issues.

Debugging Mindset Tenets

  1. Stay Empirical – Rely on observed evidence before forming theories; disprove yourself fast.
  2. Change One Variable – Isolate factors to avoid conflating causes and effects.
  3. Instrument the Unknown – Add logging, probes, or tests where visibility is lacking.
  4. Assume the Environment Matters – Account for configuration, data shape, concurrency, and timing.
  5. Document the Trail – Log assumptions, attempts, and findings so others can follow the breadcrumb path.

Diagnostic Workflow

  1. Clarify the Signal
    • Capture error messages, stack traces, screenshots, or test failures verbatim.
    • Note when, where, and how reliably the issue occurs.
  2. Reproduce Reliably
    • Build a minimal repro: failing test, script, or manual steps.
    • Confirm the failure happens under controlled conditions before modifying code.
  3. Form Hypotheses
    • Map the failing behavior to code paths, dependencies, and recent changes.
    • Prioritize hypotheses by likelihood and blast radius.
  4. Probe & Observe
    • Read relevant files, compare revisions, and search for known issues.
    • Instrument with logs, assertions, or breakpoints to collect new evidence.
  5. Isolate the Root Cause
    • Narrow scope until a single component, configuration, or data condition explains the failure.
    • Validate by toggling or patching the suspected culprit and rerunning the repro.
  6. Fix and Fortify
    • Implement the minimal fix with guardrails (tests, validation, monitoring hooks).
    • Confirm the original failure is resolved and no new regressions appear.
  7. Share the Findings
    • Summarize root cause, fix, and preventive steps (tests, docs, alerts).
    • Suggest systemic follow-ups if the defect reveals larger risks.

Read the full file on GitHub · 70 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 · 70 lines · 11 tokens per session scan A 46c63cd3c7f1

Subscribe to this mod's changes

debugging is an agent published in the GitHub repository ABilenduke/copilot-developer (4 stars, last pushed 6mo ago), licensed MIT. It adds 11 tokens to every session and 763 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 2026-08-31.

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