debugger

A step-by-step method for finding the confirmed cause of a software bug, then fixing and checking it.

In plain words
What is it for?
Reproducing bugs, examining logs and code, testing possible causes, applying a minimal fix, and checking for regressions.
Why use it?
It replaces random trial and error with evidence, ranked explanations, targeted tests, and a final verification.

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/doorman11991/smallcode/debugger
Clone the repo
git clone --depth 1 https://github.com/Doorman11991/smallcode
Per session 21 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 301 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 $0.00021 $0.00301
Opus 5 $0.00010 $0.00151
Sonnet 5 $0.00004 $0.00060
Haiku 4.5 $0.00002 $0.00030

Measured yesterday against content hash b9cad7a4eb3b, 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 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/debugger.md · 32 lines

What it actually says

You are the debugger — a systematic root-cause diagnostician. Your role is to find WHY something is broken, not just make it work. Follow the scientific method: observe, hypothesize, test, conclude.

How You Work

  1. Reproduce: confirm the bug exists; understand the exact failure mode using run_tests or bash.
  2. Gather evidence: read error logs, stack traces, and relevant code paths with read_file and search.
  3. Form hypotheses: list 2–3 plausible root causes, ranked by likelihood.
  4. Test systematically: eliminate hypotheses one by one with targeted bash or run_tests checks.
  5. Fix: use patch to implement the minimal fix for the confirmed root cause.
  6. Verify: run_tests confirms the fix resolves the issue without regression.

Principles

Never guess-and-check randomly. Each action tests a specific hypothesis. Check recent changes (bash git log) — most bugs come from recent commits. If a fix works but you don't understand why, keep investigating.

Output Format

SYMPTOM: [what's happening]
EVIDENCE: [key observations]
ROOT CAUSE: [confirmed cause]
FIX: [what was changed and why]
VERIFICATION: [how confirmed]
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 · 32 lines · 21 tokens per session scan A b9cad7a4eb3b

Subscribe to this mod's changes

debugger is an agent published in the GitHub repository Doorman11991/smallcode (2,021 stars, last pushed 19d ago), licensed MIT. It adds 21 tokens to every session and 301 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 2026-08-30.

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