sentinel

sentinel is a skill for Claude Code from Snowflake-Labs/cocoplus. It costs 63 tokens per session (2,220 once invoked), scanned A, original, MIT.

A quality gate that evaluates one project artifact across eight quality areas and returns an approved, conditional, or blocked result.

In plain words
What is it for?
Use it to verify a file, anchor the review to its SHA-256 fingerprint, and check whether it already has an approval record.
Why use it?
It combines evidence checks with a rule that serious clean-code failures can block approval, making review decisions explicit.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter. Also seen: mentions subagents.

Good fit Use it to verify a file, anchor the review to its SHA-256…

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Install with agentmods
npx agentmods add skills/snowflake-labs/cocoplus/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.

Any agent
npx skills add Snowflake-Labs/cocoplus --skill sentinel
Clone the repo
git clone --depth 1 https://github.com/Snowflake-Labs/cocoplus

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 sentinel

README.md
[![agentmods](https://agentmods.dev/badge/skills/snowflake-labs/cocoplus/sentinel.svg)](https://agentmods.dev/skills/snowflake-labs/cocoplus/sentinel)
Your own site
<a href="https://agentmods.dev/skills/snowflake-labs/cocoplus/sentinel"><img src="https://agentmods.dev/badge/skills/snowflake-labs/cocoplus/sentinel.svg" alt="Measured on agentmods" height="20"></a>
Per session 63 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,220 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 $0.00063 $0.02220
Opus 5 $0.00032 $0.01110
Sonnet 5 $0.00013 $0.00444
Haiku 4.5 $0.00006 $0.00222

Measured 3d ago against content hash 1c7565771d62, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

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 3d 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.

.cortex/skills/cocosentinel/sentinel.skill.md · 223 lines

How it starts

The opening of the file, as written. The whole thing — 223 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Objective

You are executing CocoSentinel — the artifact quality gate. Your task is to evaluate a single artifact across eight dimensions in parallel and produce an overall APPROVED / CONDITIONAL / BLOCKED verdict.

Override rule: Dimension H (Clean Code) FAIL overrides all other dimension outcomes to BLOCKED, regardless of A1–F verdicts.

Before proceeding, verify that .cocoplus/ exists in the current directory. If it does not, output: "CocoPlus is not initialized in this directory. Run $pod init to set up the CocoPlus project bundle and try again." Then stop.

Step 1 — Parse Input

The developer invoked $sentinel <file> where <file> is the artifact path. If no file was provided, ask: "Which file should CocoSentinel evaluate? Provide the file path."

Read the artifact file. If it does not exist, output: "File not found: . Verify the path and try again." Then stop.

Step 2 — Compute SHA-256 Hash

Compute the SHA-256 hash of the artifact's full content. Record it as artifact_sha. This is the evaluation anchor.

Check .cocoplus/sentinel/approvals.jsonl (if it exists) for an existing approval record matching this artifact_sha. If found:

  • Surface: "CocoSentinel: an existing approval exists for this artifact (SHA: , approved , outcome: ). Re-evaluate or accept existing approval? Type REEVAL to re-evaluate, or ACCEPT to use existing approval."
  • If ACCEPT: display the existing approval summary and stop.
  • If REEVAL: proceed with full evaluation.

Create .cocoplus/sentinel/ directory if it does not exist.

Step 3 — Load CocoWisdom Context

Read .cocoplus/wisdom/rejections.jsonl if it exists. For each dimension (A1, A2, B, C, D, E, F), extract the two most recent BLOCKED records where gate: "sentinel" and dimension matches. These become prior_rejection_context for the corresponding dimension agent.

If rejections.jsonl does not exist or has no sentinel records, prior_rejection_context is empty for all dimensions.

Read the full file on GitHub · 223 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. 3d ago First seen · 223 lines · 63 tokens per session scan A 1c7565771d62

Subscribe to this mod's changes

sentinel is a skill published in the GitHub repository Snowflake-Labs/cocoplus (720 stars, last pushed 3d ago), licensed MIT. It adds 63 tokens to every session and 2,220 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 2026-09-03.