debug-my-harness

debug-my-harness is a skill for Claude Code from zernie/vigiles. It costs 114 tokens per session (825 once invoked), scanned A, original, MIT.

A diagnostic skill that reads a local flight-recorder file containing records of agent runs. The records show which skills activated, which hooks allowed or blocked actions, and whether agents broke tool-use rules.

In plain words
What is it for?
For investigating missing skill activations, incorrect hook decisions, subagent contract violations, trigger-rate changes, and capability changes recorded in `.vigiles/runs.jsonl`.
Why use it?
It replaces guesswork with evidence when an agent behaves unexpectedly or a skill fires too often, too rarely, or at the wrong time.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter. Also seen: mentions subagents.

Part of the vigiles plugin — 26 skills, 4 hooks, 2 plugins shipped together

Good fit For investigating missing skill activations, incorrect hook decisions, subagent contract violations, trigger-rate changes, and capability changes recorded in .vigiles/runs.jsonl.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/zernie/vigiles/debug-my-harness
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.

Any agent
npx skills add zernie/vigiles --skill debug-my-harness
Clone the repo
git clone --depth 1 https://github.com/zernie/vigiles

Made for: Claude Code.

Or install vigiles, the plugin that ships this one along with the rest of its 26 skills, 4 hooks, 2 plugins.

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 debug-my-harness

README.md
[![agentmods](https://agentmods.dev/badge/skills/zernie/vigiles/debug-my-harness.svg)](https://agentmods.dev/skills/zernie/vigiles/debug-my-harness)
Your own site
<a href="https://agentmods.dev/skills/zernie/vigiles/debug-my-harness"><img src="https://agentmods.dev/badge/skills/zernie/vigiles/debug-my-harness.svg" alt="Measured on agentmods" height="20"></a>
Per session 114 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 825 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket pass 7 Aug 2026
  • Snyk pass 7 Aug 2026
How audits are shown
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 $0.00114 $0.00825
Opus 5 $0.00057 $0.00413
Sonnet 5 $0.00023 $0.00165
Haiku 4.5 $0.00011 $0.00082

Measured 8d ago against content hash 3593437b3383, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

debug-my-harness 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 8d 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.

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.

skills/debug-my-harness/SKILL.md · 58 lines

How it starts

The opening of the file, as written. The whole thing — 58 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Diagnose harness misbehavior from the flight recorder — the local, append-only ledger at .vigiles/runs.jsonl that vigiles writes as your harness runs. It records what actually happened, so you debug from evidence instead of guessing.

What's in the ledger

One JSON record per line, each with a kind:

  • hook — a compiled-hook gate decision: {event, decision: allow|deny|ask, mode: enforce|observe, rule, cmd, reason}.
  • agent — a subagent tool-contract decision: {name, tool, allowed, reason} (a false = the agent went outside its lane).
  • skill — a skill activation: {name, fired}.
  • eval — a measured metric: {name, metric, value} (e.g. trigger-rate recall/precision).
  • capability-diff — a blast-radius change: {pr, added, removed, widened}.

Instructions

Step 1: Read the ledger

Read .vigiles/runs.jsonl (JSONL — one record per line; tolerate a torn last line). If it's absent or empty, say so — there's nothing recorded yet; suggest running the harness (or vigiles audit) first. Do NOT fabricate records.

Step 2: Answer the specific question, evidence-first

Match the user's question to the ledger:

  • "Why did skill X stop firing / why does the wrong one run?" — count skill fires by name over time. If X's fire-rate dropped, look for a sibling that fired on the same kinds of prompts (a selection collision) and check their descriptions for overlap. Recommend differentiating or merging the descriptions.
  • "Why didn't my hook block that?" — find hook records for the event. A decision: allow on something that should be denied, or mode: observe (shadow, never blocks), or the absence of any record, tells you which. Recommend flipping observeenforce or fixing the gate logic.
  • "Did a subagent misbehave?" — list agent records with allowed: false: the agent reached for a tool outside its declared contract. Point at the contract to tighten or widen.
  • "Is it getting worse?" — compare eval metric values (recall/precision) across runs; a downward trend is drift (often after a harness/model upgrade).

Read the full file on GitHub · 58 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. 8d ago First seen · 58 lines · 114 tokens per session scan A 3593437b3383

Subscribe to this mod's changes

debug-my-harness is a skill published in the GitHub repository zernie/vigiles (15 stars, last pushed today), licensed MIT. It adds 114 tokens to every session and 825 once invoked, about $0.0006 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.