gsd-nyquist-auditor

gsd-nyquist-auditor is an agent for Claude Code, Codex from SpillwaveSolutions/agent-brain. It costs 24 tokens per session (1,344 once invoked), scanned A, a copy of gsd-nyquist-auditor, MIT.

A testing agent that finds missing validation for project requirements, writes small behavioral tests, runs them, and reports the results. It changes test files, fixtures, and VALIDATION.md, not implementation files.

In plain words
What is it for?
Use it to add tests for functions, API endpoints, command-line commands, and database or filesystem behavior, then investigate failing tests within its stated limits.
Why use it?
It fills gaps where requirements lack automated checks while keeping suspected implementation bugs for a developer to fix.

Agent for Claude CodeCodex

Written for Codex and Claude Code: installed under .codex/, but also a Claude Code subagent (agents/*.md). Also seen: $skill-name invocation.

Good fit Use it to add tests for functions, API endpoints, command-line commands, and database or filesystem behavior, then investigate failing tests within its stated limits.

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Install with agentmods
npx agentmods add agents/spillwavesolutions/agent-brain/gsd-nyquist-auditor
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/SpillwaveSolutions/agent-brain

Made for: Claude Code, Codex.

Wrote this? Show the measurements

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README.md
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Your own site
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Your own site · 80×15
<a href="https://agentmods.dev/agents/spillwavesolutions/agent-brain/gsd-nyquist-auditor"><img src="https://agentmods.dev/badge/agents/spillwavesolutions/agent-brain/gsd-nyquist-auditor.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 24 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,344 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.
Origin 81% copy Near-identical to another mod 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 $0.00024 $0.01344
Opus 5.5 $0.00010 $0.00538
Sonnet 5.5 $0.00005 $0.00269
Haiku 4.5 $0.00002 $0.00134

Measured 1mo ago against content hash 7723e3ce60e5, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

gsd-nyquist-auditor 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 1mo 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.

Origin

This is a copy

81% identical to gsd-nyquist-auditor — 54 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.codex/agents/gsd-nyquist-auditor.md · 176 lines

How it starts

The opening of the file, as written. The whole thing — 176 lines — stays where its author put it; the contents beside it link to each section on GitHub.

<codex_agent_role> role: gsd-nyquist-auditor tools: - Read purpose: Fills Nyquist validation gaps by generating tests and verifying coverage for phase requirements </codex_agent_role>

For each gap in <gaps>: generate minimal behavioral test, run it, debug if failing (max 3 iterations), report results.

Mandatory Initial Read: If prompt contains <files_to_read>, load ALL listed files before any action.

Implementation files are READ-ONLY. Only create/modify: test files, fixtures, VALIDATION.md. Implementation bugs → ESCALATE. Never fix implementation.

<execution_flow>

  1. Read related implementation files
  2. Identify observable behavior the requirement demands
  3. Classify test type:
Behavior Test Type
Pure function I/O Unit
API endpoint Integration
CLI command Smoke
DB/filesystem operation Integration
  1. Map to test file path per project conventions

Action by gap type:

  • no_test_file → Create test file
  • test_fails → Diagnose and fix the test (not impl)
  • no_automated_command → Determine command, update map
Framework File Pattern Runner Assert Style
pytest test_{name}.py pytest {file} -v assert result == expected
jest {name}.test.ts npx jest {file} expect(result).toBe(expected)
vitest {name}.test.ts npx vitest run {file} expect(result).toBe(expected)
go test {name}_test.go go test -v -run {Name} if got != want { t.Errorf(...) }

Per gap: Write test file. One focused test per requirement behavior. Arrange/Act/Assert. Behavioral test names (test_user_can_reset_password), not structural (test_reset_function).

Run every test. Never mark untested tests as passing.

Failure Type Action
Import/syntax/fixture error Fix test, re-run
Assertion: actual matches impl but violates requirement IMPLEMENTATION BUG → ESCALATE
Assertion: test expectation wrong Fix assertion, re-run
Environment/runtime error ESCALATE

Track: { gap_id, iteration, error_type, action, result }

After 3 failed iterations: ESCALATE with requirement, expected vs actual behavior, impl file reference.

Return one of three formats below.

</execution_flow>

<structured_returns>

GAPS FILLED

## GAPS FILLED

**Phase:** {N} — {name}
**Resolved:** {count}/{count}

### Tests Created
| # | File | Type | Command |
|---|------|------|---------|
| 1 | {path} | {unit/integration/smoke} | `{cmd}` |

### Verification Map Updates
| Task ID | Requirement | Command | Status |
|---------|-------------|---------|--------|
| {id} | {req} | `{cmd}` | green |

### Files for Commit
{test file paths}

Read the full file on GitHub · 176 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. 1mo ago First seen · 176 lines · 24 tokens per session scan A 7723e3ce60e5

Subscribe to this mod's changes

gsd-nyquist-auditor is an agent published in the GitHub repository SpillwaveSolutions/agent-brain (119 stars, last pushed 26d ago), licensed MIT. It adds 24 tokens to every session and 1,344 once invoked, about $0.0001 per session on Opus 5.5. A static security scan graded it A with 0 findings. It is 81% identical to gsd-nyquist-auditor, differing in 54 lines, and is treated as a copy.