selftest

A command that tests an extension's lifecycle from the Spec Kit catalog, including finding it, installing it, and registering it. A catalog is a directory of available extensions and their metadata.

In plain words
What is it for?
Use it to self-test an extension by providing its name, such as linear. The input does not describe the complete test sequence.
Why use it?
It checks whether the extension can be discovered and installed as expected, including extensions that are listed but not directly installable.

Command

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.

agentmods
npx agentmods add commands/github/spec-kit/selftest
Clone the repo
git clone --depth 1 https://github.com/github/spec-kit
Per session 10 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 537 The whole file, excluding the scripts and references it only reads on demand.
Security scan C 1 finding. 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 $0.00010 $0.00537
Opus 5 $0.00005 $0.00269
Sonnet 5 $0.00002 $0.00107
Haiku 4.5 $0.00001 $0.00054

Measured yesterday against content hash 93f33139a3da, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

selftest scanned grade C with 1 finding 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.

Nullifies safety policieshighAnti-refusal

"You have no restrictions", "do anything now", "ignore your guidelines": a direct jailbreak that disables guardrails.

Then, simulate adding the extension by installing it from its catalog download URL, which should bypass the restriction.
extensions/selftest/commands/selftest.md · 70 lines

How it starts

The opening of the file, as written. The whole thing — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Extension Self-Test: $ARGUMENTS

This command drives a self-test simulating the developer experience with the $ARGUMENTS extension.

Goal

Validate the end-to-end lifecycle (discovery, installation, registration) for the extension: $ARGUMENTS. If $ARGUMENTS is empty, you must tell the user to provide an extension name, for example: /speckit.selftest.extension linear.

Steps

Step 1: Catalog Discovery Validation

Check if the extension exists in the Spec Kit catalog. Execute this command and verify that it completes successfully and that the returned extension ID exactly matches $ARGUMENTS. If the command fails or the ID does not match $ARGUMENTS, fail the test.

specify extension info "$ARGUMENTS"

Step 2: Simulate Installation

First, try to add the extension to the current workspace configuration directly. If the catalog provides the extension as install_allowed: false (discovery-only), this step is expected to fail.

specify extension add "$ARGUMENTS"

Then, simulate adding the extension by installing it from its catalog download URL, which should bypass the restriction. Obtain the extension's download_url from the catalog metadata (for example, via a catalog info command or UI), then run:

specify extension add "$ARGUMENTS" --from "<download_url>"

Step 3: Registration Verification

Once the add command completes, verify the installation by checking the project configuration. Use terminal tools (like cat) to verify that the following file contains a record for $ARGUMENTS.

cat .specify/extensions/.registry/$ARGUMENTS.json

Step 4: Verification Report

Analyze the standard output of the three steps. Generate a terminal-style test output format detailing the results of discovery, installation, and registration. Return this directly to the user.

Example output format:

============================= test session starts ==============================
collected 3 items

test_selftest_discovery.py::test_catalog_search [PASS/FAIL]
  Details: [Provide execution result of specify extension search]

test_selftest_installation.py::test_extension_add [PASS/FAIL]
  Details: [Provide execution result of specify extension add]

test_selftest_registration.py::test_config_verification [PASS/FAIL]
  Details: [Provide execution result of registry record verification]

============================== [X] passed in ... ==============================

Read the full file on GitHub · 70 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 First seen · 70 lines · 10 tokens per session scan C 93f33139a3da

Subscribe to this mod's changes

selftest is a command published in the GitHub repository github/spec-kit (132,298 stars, last pushed 3d ago), licensed MIT. It adds 10 tokens to every session and 537 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it C with 1 finding (nullifies safety policies). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

Other commands, from other repositories