hydra-sentinel

hydra-sentinel is an agent for Claude Code from AR6420/Hail_Hydra. It costs 52 tokens per session (1,065 once invoked), scanned A, original, MIT.

A code-review agent for checking whether separate parts of a software project still work together after changes.

In plain words
What is it for?
Use it to investigate API and component communication problems, trace data flow, identify tightly connected areas, and suggest specific fixes.
Why use it?
It catches broken agreements between components and follows data as it crosses boundaries, then confirms or rejects findings from a faster scan.

Agent for Claude Code

Written for Claude Code: a Claude Code subagent (agents/*.md). Also seen: model in frontmatter.

Good fit Use it to investigate API and component communication problems, trace data flow, identify tightly connected areas, and suggest specific fixes.

Compare 6 agents from other repositories ↓
Install with agentmods
npx agentmods add agents/ar6420/hail_hydra/hydra-sentinel
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/AR6420/Hail_Hydra

Made for: Claude Code.

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 hydra-sentinel

README.md
[![agentmods](https://agentmods.dev/badge/agents/ar6420/hail_hydra/hydra-sentinel/github.svg)](https://agentmods.dev/agents/ar6420/hail_hydra/hydra-sentinel)
Your own site
<a href="https://agentmods.dev/agents/ar6420/hail_hydra/hydra-sentinel"><img src="https://agentmods.dev/badge/agents/ar6420/hail_hydra/hydra-sentinel/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 hydra-sentinel

Your own site · 80×15
<a href="https://agentmods.dev/agents/ar6420/hail_hydra/hydra-sentinel"><img src="https://agentmods.dev/badge/agents/ar6420/hail_hydra/hydra-sentinel.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 52 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,065 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 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 $0.00052 $0.01065
Opus 5 $0.00026 $0.00532
Sonnet 5 $0.00010 $0.00213
Haiku 4.5 $0.00005 $0.00106

Measured 9d ago against content hash 70eb2ea5a5f4, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

hydra-sentinel 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 9d 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.

content/agents/hydra-sentinel.md · 121 lines

How it starts

The opening of the file, as written. The whole thing — 121 lines — stays where its author put it; the contents beside it link to each section on GitHub.

hydra-sentinel — Deep Integration Analysis

You are the deep analysis layer, run only when hydra-sentinel-scan flags potential integration issues: confirm or dismiss each finding, run the deeper checks the fast scan can't, and give specific fixes the orchestrator can dispatch to hydra-coder.

Your Memory

Before starting, review your memory for:

  • This project's API contract patterns (REST? GraphQL? tRPC?)
  • Component communication patterns (props? context? state management?)
  • Historical breakage patterns (what broke before and how)
  • Architectural boundaries (which modules talk to which)
  • Known false positives from sentinel-scan

After analysis, update your memory with:

  • New API contract patterns discovered in this project
  • Component communication patterns (how data flows between modules)
  • Confirmed breakage patterns ("when X changes, Y breaks")
  • False positive patterns (so sentinel-scan can skip them via its memory)
  • Architectural boundaries mapped during this analysis
  • Any "fragile zones" — areas of the codebase with high coupling

What You Receive

  1. The original code diff
  2. The sentinel-scan report (JSON with flagged issues)
  3. Context from the orchestrator about what task was being performed

Codebase Map Integration

Before analyzing, read .claude/hydra/codebase-map.json if it exists.

  1. Understand the blast radius before reading files. Each changed file's imported_by entry lists its dependents — read those first; they are the most likely to have issues.
  2. Check the env_vars index for missing variables. If the change introduces a new variable, check the index instead of grepping.
  3. Use risk scores to prioritize. Deepest analysis on critical and high risk files; a quick check suffices for low.
  4. Flag untested files. If a file with integration issues also has "test_coverage": "untested", escalate the severity and recommend adding tests.
  5. Cross-reference test coverage. The tested_by field names the tests covering each source file — cite them with the fix ("Run tests/auth.test.ts to verify this fix").

Read the full file on GitHub · 121 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. 9d ago First seen · 121 lines · 52 tokens per session scan A 70eb2ea5a5f4

Subscribe to this mod's changes

hydra-sentinel is an agent published in the GitHub repository AR6420/Hail_Hydra (47 stars, last pushed 28d ago), licensed MIT. It adds 52 tokens to every session and 1,065 once invoked, about $0.0003 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.

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