grackle: Skill for Claude Code

.claude/skills/test-claude-runtime/SKILL.md

test-claude-runtime is a skill for Claude Code from nick-pape/grackle. It costs 53 tokens per session (734 once invoked), scanned A, original, MIT.

A test workflow for starting and exercising the native Claude Code runtime against an isolated Grackle test server. It lists supported Claude models and explains an issue where native Claude Code may not report real tool failures.

In plain words
What is it for?
Use it to spawn Claude Code with Sonnet, Opus, or Haiku, test personas, and investigate whether tool calls and failures are being reported correctly.
Why use it?
It provides a repeatable way to check the Claude runtime and prevents misleading test results caused by synthetic or missing tool-result error messages.

Skill for Claude Code

Written for Claude Code: installed under .claude/. Also seen: mentions Claude Code; mentions Codex.

This is nick-pape/grackle's own configuration. It tells Claude Code how to work on grackle itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything grackle configures →

Reuse

Borrowing it

Nothing to install: this file belongs to nick-pape/grackle. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/nick-pape/grackle/main/.claude/skills/test-claude-runtime/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/nick-pape/grackle

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 test-claude-runtime

README.md
[![agentmods](https://agentmods.dev/badge/skills/nick-pape/grackle/test-claude-runtime.svg)](https://agentmods.dev/skills/nick-pape/grackle/test-claude-runtime)
Your own site
<a href="https://agentmods.dev/skills/nick-pape/grackle/test-claude-runtime"><img src="https://agentmods.dev/badge/skills/nick-pape/grackle/test-claude-runtime.svg" alt="Measured on agentmods" height="20"></a>
Per session 53 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 734 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 5.1 $0.00053 $0.00734
Opus 5 $0.00026 $0.00367
Sonnet 5 $0.00011 $0.00147
Haiku 4.5 $0.00005 $0.00073

Measured 6d ago against content hash 75546334d3a9, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

test-claude-runtime 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 6d 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.

.claude/skills/test-claude-runtime/SKILL.md · 57 lines

How it starts

The opening of the file, as written. The whole thing — 57 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Test the Claude Code runtime

How to spawn the native claude-code runtime against an isolated test server and observe its behavior. Assumes you've started a server with /launch-grackle (and have GRACKLE_URL + GRACKLE_API_KEY exported).

Allowed model names ✅

Model Works? Notes
sonnet Default persona (claude-code / "Software Engineer") uses this
opus
haiku

No model gating — native Claude Code works out of the box (subscription/OAuth). These are the values grackle runtimes advertises and they all spawn.

Spawn it

The default persona already uses claude-code:

grackle spawn local "<prompt>"                       # uses default persona (claude-code / sonnet)

Or make an explicit persona (e.g. to pick opus):

grackle persona create "Claude Opus Tester" --runtime claude-code --model opus --prompt "You are a test agent."
grackle spawn local "<prompt>" --persona claude-opus-tester

⚠️ Key gotcha: native Claude Code does NOT surface real tool failures

The Claude Agent SDK runs tools internally and (in streaming mode) does not emit real tool_result blocks with is_error. The adapter instead emits synthetic empty tool_result events that are always successful (flushPendingToolResultscontent: "", is_error: false).

Verified live: prompting Claude Code to run a failing command (cat /nonexistent) produced tool_result events with content: {"is_ok":true,...} (empty) — the failure was not observable. This is the separate bug 1c (filed off #1355).

Implication: you cannot demonstrate a tool failure through native claude-code. The adapter's b.is_error read (packages/runtime-claude-code/src/claude-code.ts) is only exercised when the SDK does surface tool_result blocks (some non-streaming modes). To observe a real Claude tool failure, use the ACP variant (see /test-acp-runtime — now that #1366 is fixed) — its tool_call_update carries a real status: failed (validated live).

Read the full file on GitHub · 57 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. 6d ago First seen · 57 lines · 53 tokens per session scan A 75546334d3a9

Subscribe to this mod's changes

test-claude-runtime is a skill published in the GitHub repository nick-pape/grackle (21 stars, last pushed 2mo ago), licensed MIT. It adds 53 tokens to every session and 734 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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