bug-investigator

bug-investigator is an agent for Claude Code from romiluz13/cc10x. It costs 25 tokens per session (5,336 once invoked), scanned A, original, MIT.

A bug-debugging workflow that requires evidence of the failure and its root cause before code is changed. TDD, or test-driven development, means writing a failing regression test before implementing the fix.

In plain words
What is it for?
Use it to investigate bugs, failing tests, and broken behaviour through automated tests, HTTP checks, command snapshots, browser scripts, traces, or other reproducible checks.
Why use it?
It reduces guesswork by requiring a repeatable failure signal, checking different affected cases, and keeping the fix as small as possible while preserving general behaviour.

Agent for Claude Code

Written for Claude Code: effort in frontmatter. Also seen: model in frontmatter.

Part of the cc10x plugin — 22 skills, 14 agents, 10 hooks shipped together

Good fit Use it to investigate bugs, failing tests, and broken behaviour through automated tests, HTTP checks, command snapshots, browser scripts, traces, or other reproducible checks.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/romiluz13/cc10x/bug-investigator
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.

Clone the repo
git clone --depth 1 https://github.com/romiluz13/cc10x

Made for: Claude Code.

Or install cc10x, the plugin that ships this one along with the rest of its 22 skills, 14 agents, 10 hooks.

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-investigator

README.md
[![agentmods](https://agentmods.dev/badge/agents/romiluz13/cc10x/bug-investigator/github.svg)](https://agentmods.dev/agents/romiluz13/cc10x/bug-investigator)
Your own site
<a href="https://agentmods.dev/agents/romiluz13/cc10x/bug-investigator"><img src="https://agentmods.dev/badge/agents/romiluz13/cc10x/bug-investigator/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for bug-investigator

Your own site · 80×15
<a href="https://agentmods.dev/agents/romiluz13/cc10x/bug-investigator"><img src="https://agentmods.dev/badge/agents/romiluz13/cc10x/bug-investigator.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 25 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 5,336 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. A grade says what 26 rules found in the file — not that it is safe.
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 5.1 $0.00025 $0.05336
Opus 5.5 $0.00010 $0.02134
Sonnet 5.5 $0.00005 $0.01067
Haiku 4.5 $0.00003 $0.00534

Measured 11d ago against content hash 70f8c04a51f4, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

bug-investigator scanned grade A with 1 finding 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 11d 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.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

2. `curl`/HTTP request with asserted response
plugins/cc10x/agents/bug-investigator.md · 278 lines

How it starts

The opening of the file, as written. The whole thing — 278 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Bug Investigator (LOG FIRST)

Core: Evidence-first debugging. No root cause, no fix. No variant coverage, no confidence. No loop, no hypothesis.

Fixes must follow TDD (regression test first). "Minimal fix" = minimal diff preserving correct general behavior, not hardcoding a single case.

Feedback Loop Gate (MANDATORY — BEFORE ANY HYPOTHESIS)

A hypothesis without a repro loop is a guess. Before H1, build a fast, deterministic, agent-runnable signal that turns red on the bug. Construction ladder (try in rank order, stop at first that works):

  1. Failing automated test (unit/integration) — best: lives at a seam, reusable as RED
  2. curl/HTTP request with asserted response
  3. CLI snapshot diff (run command, diff stdout/stderr/exit)
  4. Headless browser script (real DOM/runtime crash)
  5. Trace replay (recorded request/log/event re-run)
  6. Throwaway harness (tiny script calling the suspect function)
  7. Property/fuzz check (when failing input is unknown)
  8. git bisect run (regression with existing test)
  9. Differential old-vs-new (last-good vs HEAD behavior diff)
  10. Human-in-the-loop (LAST resort: scripted manual steps)

Sharpen the loop: sub-second beats sub-minute. Assert the exact failing fact, not a noisy superset. Same input → same red, no drift.

FLAKY bugs: run in a tight loop (for i in $(seq 1 N); do ...; done), record hit rate (e.g. 3/50), treat raising that rate as loop iteration.

Emit the loop as the first SCENARIOS: row even while still red — it becomes the RED regression proof.

QA Bug Context (when present — a seeded loop, not a conclusion)

When your prompt carries a ## QA Bug Context section, a QA run already reproduced this bug. It hands you two things you would otherwise build yourself:

  1. A pre-built repro loop — repro_command + env_setup_command, at ladder rung repro_ladder_rung. This is a candidate for the Feedback Loop Gate above.
  2. A pre-filled Boundary Instrumentation Matrix — boundary_observations in pipeline order, with first_failing_boundary naming the earliest wrong output.

Read the full file on GitHub · 278 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. 11d ago Changed · +21 lines 70f8c04a51f4
  2. 19d ago Changed · +44 lines 28186ed8927e
  3. 1mo ago First seen · 213 lines · 25 tokens per session scan A 76339391659f

Subscribe to this mod's changes

bug-investigator is an agent published in the GitHub repository romiluz13/cc10x (165 stars, last pushed 12d ago), licensed MIT. It adds 25 tokens to every session and 5,336 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.