A skill for stopping running or paused executions, which are tasks still active in the background. It can cancel one execution, all executions, or let you choose from a list.

Use it to cancel an execution by ID, stop everything with `--all`, or interactively choose a task to stop.

It removes stuck or abandoned tasks that would otherwise keep running and consuming resources.

cancel — Skill for Claude Code by Q00: A skill for stopping running or paused executions, which…

About the project

Q00/ouroboros is an Agent OS for running coding agents through interviews, staged evaluation, and repeated improvement cycles. It helps developers turn vague requests into tested code across multiple agent runtimes. Its catalogue add-ons provide workflows, agents, hooks, instructions, and integrations for operating those processes.

Q00/ouroboros · 5,769 stars · on GitHub · ouroboros.page

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 skills/q00/ouroboros/cancel

Any agent

npx skills add Q00/ouroboros --skill cancel

Clone the repo

git clone --depth 1 https://github.com/Q00/ouroboros

Made for: Claude Code.

Or install ouroboros, the plugin that ships this one along with the rest of its 22 skills, 21 agents, 3 hooks, 1 MCP server.

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/q00/ouroboros/cancel.svg)](https://agentmods.dev/skills/q00/ouroboros/cancel)

Your own site

<a href="https://agentmods.dev/skills/q00/ouroboros/cancel"><img src="https://agentmods.dev/badge/skills/q00/ouroboros/cancel.svg" alt="Measured on agentmods" height="20"></a>

Per session 8 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,007 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.

Model	Per session	Once invoked
Fable 5.1	$0.00008	$0.01007
Opus 5	$0.00004	$0.00504
Sonnet 5	$0.00002	$0.00201
Haiku 4.5	$0.00001	$0.00101

Measured 3d ago against content hash 3e9eede8dda5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

cancel 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.

skills/cancel/SKILL.md · 116 lines

How it starts

The opening of the file, as written. The whole thing — 116 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/ouroboros:cancel

Cancel stuck or orphaned executions by session ID, cancel all running sessions, or interactively pick from active executions.

Usage

/ouroboros:cancel                          # Interactive: list active, pick one
/ouroboros:cancel <execution_id>           # Cancel specific execution
/ouroboros:cancel --all                    # Cancel all running executions

Trigger keywords: "cancel execution", "kill session", "stop running", "abort execution"

How It Works

This skill interacts directly with the event store (not via MCP tool) to emit cancellation events. It uses the CLI command under the hood.

Three modes:

Bare (no args): Lists all active (running/paused) executions in a numbered table and prompts you to pick one to cancel
Explicit (execution_id): Cancels the specified execution immediately
--all flag: Cancels every running or paused execution at once

Instructions

When the user invokes this skill:

Determine which mode to use:
- If the user provided an execution/session ID: Explicit mode
- If the user says "cancel all" or "cancel everything": --all mode
- If no ID given and not "all": Bare mode (interactive listing)
Run the appropriate CLI command using Bash:

Bare mode (interactive):
```
ouroboros cancel execution
```
This will list active executions and prompt for selection.

Explicit mode (specific execution):
```
ouroboros cancel execution <execution_id>
```
Cancel all mode:
```
ouroboros cancel execution --all
```
With custom reason:
```
ouroboros cancel execution <execution_id> --reason "Stuck for 2 hours"
```
Present results to the user:
- Show which executions were cancelled
- If bare mode, show the list and selection prompt
- If no active executions, inform the user
End with a next-step suggestion:
- After cancellation: ◆ Cancelled — use ooo status to verify, or ooo run to start fresh
- No active sessions: ◆ No active executions — use ooo run to start a new one

Read the full file on GitHub · 116 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.

3d ago Changed · +10 lines 3e9eede8dda5
6d ago First seen · 106 lines · 8 tokens per session scan A 13a090a36b28

Subscribe to this mod's changes

cancel is a skill published in the GitHub repository Q00/ouroboros (5,769 stars, last pushed yesterday), licensed MIT. It adds 8 tokens to every session and 1,007 once invoked, about $0.0000 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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cancel