arena-new-prompt

arena-new-prompt is a command for Claude Code from fmflurry/settings-opencode. It costs 17 tokens per session (2,080 once invoked), scanned A, original, MIT.

A code generator for adding a new prompt adapter to an LLM arena benchmark, a test system that compares language-model outputs. It follows the project's existing classify and draft structure and produces code plus a manual wiring checklist.

In plain words
What is it for?
Use it to scaffold a new benchmark prompt, such as sentiment or summarization, from a prompt ID. It creates the adapter implementation and related test-case structure.
Why use it?
It removes the repetitive work of creating the adapter files and matching the required interface and layout. It also highlights the remaining setup steps instead of leaving the new benchmark disconnected.

Command for Claude Code

Written for Claude Code: $ARGUMENTS substitution.

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is import type { <PromptIdInput> } from '../../src/agents/dunning/<promptId>.schemas.ts';.

Good fit Use it to scaffold a new benchmark prompt, such as sentiment or summarization, from a prompt ID. It creates the adapter implementation and related test-case structure.

Compare 6 commands from other repositories ↓
Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/fmflurry/settings-opencode
agentmods
npx agentmods add commands/fmflurry/settings-opencode/arena-new-prompt

Made for: Claude Code.

Wrote this? Show the measurements

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README.md
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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 arena-new-prompt

Your own site · 80×15
<a href="https://agentmods.dev/commands/fmflurry/settings-opencode/arena-new-prompt"><img src="https://agentmods.dev/badge/commands/fmflurry/settings-opencode/arena-new-prompt.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 17 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,080 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 $0.00017 $0.02080
Opus 5.5 $0.00007 $0.00832
Sonnet 5.5 $0.00003 $0.00416
Haiku 4.5 $0.00002 $0.00208

Measured 26d ago against content hash 414bc9c2ff57, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

arena-new-prompt 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 26d 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/commands/arena-new-prompt.md · 172 lines

How it starts

The opening of the file, as written. The whole thing — 172 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Arena New Prompt

CC: Scaffold a new bench-able prompt following the real PromptAdapter<TInput,TOutput,TGroundTruth> contract and verified file layout. Read the task below carefully to understand the structure before generating code.

Generate a new prompt adapter for the LLM arena: $ARGUMENTS

Your Task

Scaffold a complete, working prompt adapter following the proven classify / draft pattern. Your job is to generate code (the coder role), then emit a wiring checklist for manual completion by the user.

1. Parse Arguments

From $ARGUMENTS, extract:

  • promptId: The new prompt's ID (e.g., sentiment, summarize). Used as a stable machine-readable identifier in types, filenames, and exports.

2. Generate Code Artifacts

Create the following files (structure mirrors bench/cases-classify/ and bench/prompts/classify.adapter.ts):

A. Adapter Implementation: ai-sdk/bench/prompts/<promptId>.adapter.ts

A concrete implementation of PromptAdapter<TInput, TOutput, TGroundTruth> (see bench/prompts/prompt-adapter.ts for the contract). Must include:

  • id: PromptId field set to the new promptId
  • runInstrumented(input: TInput, options?: AdapterRunOptions) — calls the production instrumented agent function for this prompt
  • loadCases() — returns the labeled bench cases array
  • scorers(output: TOutput, groundTruth: TGroundTruth, meta) — returns CriterionResult[] from deterministic scoring

Reference: bench/prompts/classify.adapter.ts (lines 1–49) — mirrors this exactly, swapping classifyThreadInstrumented for your prompt's production instrumented function and CLASSIFY_FALLBACK_CASES for your cases export.

B. Adapter Tests: ai-sdk/bench/prompts/<promptId>.adapter.test.ts

Unit tests verifying the adapter loads cases, calls the instrumented function, and applies scorers correctly. Use node:test's mock.module() to stub the production function without network calls.

Reference: bench/prompts/classify.adapter.test.ts (full file) — copy the mocking pattern and structure, replace classifyAdapter/Classification with your adapter/output type.

Read the full file on GitHub · 172 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. 26d ago First seen · 172 lines · 17 tokens per session scan A 414bc9c2ff57

Subscribe to this mod's changes

arena-new-prompt is a command published in the GitHub repository fmflurry/settings-opencode (171 stars, last pushed yesterday), licensed MIT. It adds 17 tokens to every session and 2,080 once invoked, about $0.0001 per session on Opus 5.5. 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 2026-09-20.