Morgana: Skill for Claude Code

.claude/skills/harness-execution/SKILL.md

harness-execution is a skill for Claude Code from mdesalvo/Morgana. It costs 58 tokens per session (4,132 once invoked), scanned A, original, Apache-2.0.

A skill that runs PromptHarness, a test program for checking prompts against a configured language-model provider.

In plain words
What is it for?
Use it when you need to launch PromptHarness scenarios against the configured provider and choose which test classes and pass level to use.
Why use it?
It makes it possible to run selected prompt tests with a chosen pass threshold, while making the real model usage and cost explicit.

Skill for Claude Code

Written for Claude Code: installed under .claude/. Also seen: names the AskUserQuestion tool.

This is mdesalvo/Morgana's own configuration. It tells Claude Code how to work on Morgana 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 Morgana configures →

Reuse

Borrowing it

Nothing to install: this file belongs to mdesalvo/Morgana. 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/mdesalvo/Morgana/main/.claude/skills/harness-execution/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/mdesalvo/Morgana

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.

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README.md
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Your own site
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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 harness-execution

Your own site · 80×15
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Per session 58 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,132 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. Third-party audits
  • NVIDIA SkillSpector pass 7 Sept 2026
How audits are shown
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 $0.00058 $0.04132
Opus 5.5 $0.00023 $0.01653
Sonnet 5.5 $0.00012 $0.00826
Haiku 4.5 $0.00006 $0.00413

Measured yesterday against content hash 91ee9c3f9815, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

harness-execution 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 yesterday.

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/harness-execution/SKILL.md · 209 lines

How it starts

The opening of the file, as written. The whole thing — 209 lines — stays where its author put it; the contents beside it link to each section on GitHub.

HarnessExecution

Runs the PromptHarness (PromptHarness/PromptHarness.csproj) on demand against whichever LLM providers are currently configured in User Secrets (Morgana:LanguageModels:Tiers), against a user-chosen scope and a user-chosen global run/pass threshold. Live LLM calls, real cost — never runs without the two questions below being answered first.

Trigger

Activated when the user says things like:

  • "run the harness"
  • "execute the prompt harness"
  • "launch the harness"
  • Any request to run PromptHarness scenarios against the current provider

Procedure

  1. Confirm the active providers before anything else: read Morgana:LanguageModels:Tiers from the shared User Secrets store (UserSecretsId 374228be-4f26-4382-a3ef-7500a0b829dd, same as Morgana.Web) without printing the ApiKey/Endpoint values and tell the user which provider and model each tier (Economy / Efficiency / Performance: Provider and Options.ModelId) and Morgana:ActorSystem:Tier this run will hit. This is the harness's own design (PromptHarness/README.md): it never has its own Morgana: config, it inherits the host's. The same file is where Harness:HarnessDirectory lives when the user has overridden it (see step 7), so read both in one pass. Note the store is written with a UTF-8 BOM: parse it as utf-8-sig, or a plain JSON read fails on the first character.

  2. Ask the target scope with AskUserQuestion, multi-select. Enumerate PromptHarness/Tests/ first and offer what is actually there — the class list below is a description of a moving directory, not a contract, and a --filter naming a class that no longer exists runs zero tests and exits 0: a green nobody asked for. Eighteen classes at the time of writing, in four families:

    Deterministic — no model, no cost. Run them first: they are the cheapest way to learn the topology under test is sane before any billed turn.

    • Startup validation (StartupValidationTests — an incoherent partner declaration must stop the boot)
    • Agent card (AgentCardTests — the published card and how far the gate behind it reaches)
    • Peer federation (PeerFederationTests — the outbound half: which cards this side accepts, what it signs, where a credential may go)
    • Conversation API (ConversationApiTests — who the channel API lets in, what a start must announce, how an unknown conversation is answered. The conversations it needs on record are synthesised into the run's storage; its one model call is the presentation of its single real start)

Read the full file on GitHub · 209 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. yesterday Changed · +2 lines 91ee9c3f9815
  2. 5d ago Changed · +2 lines 4ded9230c700
  3. 6d ago Changed b4760aea4aef
  4. 8d ago Changed · +2 lines 94da63ad69e1
  5. 10d ago Changed · +110 lines b8f860b0858f
  6. 19d ago Changed · -119 lines c2fee1e54d41
  7. 21d ago Changed 33b59bcbc93d
  8. 26d ago Changed · +11 lines e78f6100d962
  9. 1mo ago Changed · +4 lines 07ebdc46d18a
  10. 1mo ago First seen · 197 lines · 58 tokens per session scan A d7c4ad34b002

Subscribe to this mod's changes

harness-execution is a skill published in the GitHub repository mdesalvo/Morgana (10 stars, last pushed yesterday), licensed Apache-2.0. It adds 58 tokens to every session and 4,132 once invoked, about $0.0002 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 2026-08-31.

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