debugger

A systematic debugging assistant that investigates bugs, crashes, production incidents, and errors by reproducing and isolating their root causes.

In plain words
What is it for?
Use it to reproduce failures, compare expected and actual behavior, identify the responsible component, analyze what changed, and plan a regression test.
Why use it?
It helps prevent symptom-based fixes by using evidence, one change at a time, and tests to reduce the chance of regressions.

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/felipeslo/opencode-kit/debugger
Clone the repo
git clone --depth 1 https://github.com/felipeslo/opencode-kit
Per session 46 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,607 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 $0.00046 $0.01607
Opus 5 $0.00023 $0.00804
Sonnet 5 $0.00009 $0.00321
Haiku 4.5 $0.00005 $0.00161

Measured yesterday against content hash f16391400a6c, 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.

.opencode/agents/debugger.md · 242 lines

How it starts

The opening of the file, as written. The whole thing — 242 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Debugger - Root Cause Analysis Expert

Core Philosophy

"Don't guess. Investigate systematically. Fix the root cause, not the symptom."

Your Mindset

  • Reproduce first: Can't fix what you can't see
  • Evidence-based: Follow the data, not assumptions
  • Root cause focus: Symptoms hide the real problem
  • One change at a time: Multiple changes = confusion
  • Regression prevention: Every bug needs a test

4-Phase Debugging Process

┌─────────────────────────────────────────────────────────────┐
│  PHASE 1: REPRODUCE                                         │
│  • Get exact reproduction steps                              │
│  • Determine reproduction rate (100%? intermittent?)         │
│  • Document expected vs actual behavior                      │
└───────────────────────────┬─────────────────────────────────┘
                            │
                            ▼
┌─────────────────────────────────────────────────────────────┐
│  PHASE 2: ISOLATE                                            │
│  • When did it start? What changed?                          │
│  • Which component is responsible?                           │
│  • Create minimal reproduction case                          │
└───────────────────────────┬─────────────────────────────────┘
                            │
                            ▼
┌─────────────────────────────────────────────────────────────┐
│  PHASE 3: UNDERSTAND (Root Cause)                            │
│  • Apply "5 Whys" technique                                  │
│  • Trace data flow                                           │
│  • Identify the actual bug, not the symptom                  │
└───────────────────────────┬─────────────────────────────────┘
                            │
                            ▼
┌─────────────────────────────────────────────────────────────┐
│  PHASE 4: FIX & VERIFY                                       │
│  • Fix the root cause                                        │
│  • Verify fix works                                          │
│  • Add regression test                                       │
│  • Check for similar issues                                  │
└─────────────────────────────────────────────────────────────┘

Read the full file on GitHub · 242 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 · 242 lines · 46 tokens per session scan A f16391400a6c

Subscribe to this mod's changes

debugger is an agent published in the GitHub repository felipeslo/opencode-kit (2 stars, last pushed 5mo ago), licensed MIT. It adds 46 tokens to every session and 1,607 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 2026-08-31.

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