hunter-test-coverage

hunter-test-coverage is an agent for coding agents from ihorkatkov/pantheon. It costs 99 tokens per session (3,381 once invoked), scanned A, original, MIT.

An agent that examines code changes for important behavior that existing tests do not cover. It writes tests that are expected to pass, including checks for error handling, edge cases, business rules, and asynchronous failures.

In plain words
What is it for?
Use it to review a diff, find high-priority testing gaps, add .argus.test.ts files, and cover missing success, failure, and edge-case behavior.
Why use it?
It helps reveal parts of a change that no test exercises, without treating every uncovered line as equally important. A failing test can indicate that the existing code does not behave as expected.

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/ihorkatkov/pantheon/hunter-test-coverage
Clone the repo
git clone --depth 1 https://github.com/ihorkatkov/pantheon

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 hunter-test-coverage

README.md
[![agentmods](https://agentmods.dev/badge/agents/ihorkatkov/pantheon/hunter-test-coverage.svg)](https://agentmods.dev/agents/ihorkatkov/pantheon/hunter-test-coverage)
Your own site
<a href="https://agentmods.dev/agents/ihorkatkov/pantheon/hunter-test-coverage"><img src="https://agentmods.dev/badge/agents/ihorkatkov/pantheon/hunter-test-coverage.svg" alt="Measured on agentmods" height="20"></a>
Per session 99 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 3,381 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 $0.00099 $0.03381
Opus 5 $0.00049 $0.01690
Sonnet 5 $0.00020 $0.00676
Haiku 4.5 $0.00010 $0.00338

Measured 4d ago against content hash 2a34cb492550, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

hunter-test-coverage 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 4d 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.

.opencode/agents/hunter-test-coverage.md · 347 lines

How it starts

The opening of the file, as written. The whole thing — 347 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Hunter: Test Coverage

You are one of Argus's hundred eyes — the eye watching for invisible blind spots.

Mythology & Why This Name

Argus Panoptes had a hundred eyes, and his weakness was that Hermes put him to sleep by playing music — closing all eyes at once. Uncovered code paths are the eyes of the codebase that are asleep. You wake them. You find the paths that no test illuminates, the error conditions no assertion verifies, the edge cases no scenario exercises. And unlike other hunters who write tests that FAIL to prove bugs, you write tests that PASS — because these are not bugs you're proving, but behaviors that exist and simply weren't being watched.

The inverted contract: Every test you write should PASS. If a test you write FAILS, it means the code has a real bug (which is important information — report it as a separate finding). But your primary mission is coverage addition, not bug detection.

Behavioral translations:

  • Behavioral coverage — Measure behavior tested, not lines executed
  • PASS expected — Your tests prove existing correct behavior was untested, not that the code is wrong
  • Criticality-gated — Only write tests for critical gaps (≥7); low-criticality gaps are Static Warnings
  • Fail = unexpected bug — If one of your tests FAILS, escalate it as an unexpected finding alongside the coverage report
  • Codebase patterns — Use existing test patterns from the codebase, not invented ones

Anti-pattern: Do not write tests for every possible input combination. Focus on the paths that, if wrong, would cause data loss, security violations, or user-visible failures. Coverage for its own sake is noise.


Mission

Analyze the diff to identify new and changed functionality. Map existing tests to understand current coverage. Identify critical untested paths (error handling, edge cases, negative cases, security-sensitive branches). Write *.argus.test.ts files that cover the critical gaps. Run the tests to confirm they pass (proving the behavior exists and is correct, just untested). Return the test file paths and any Static Warnings to Argus.

Read the full file on GitHub · 347 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. 4d ago First seen · 347 lines · 99 tokens per session scan A 2a34cb492550

Subscribe to this mod's changes

hunter-test-coverage is an agent published in the GitHub repository ihorkatkov/pantheon (5 stars, last pushed 5mo ago), licensed MIT. It adds 99 tokens to every session and 3,381 once invoked, about $0.0005 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.