task-cancel

A command for stopping background tasks started by workflow commands.

In plain words
What is it for?
Use it to cancel one task by ID, force cancellation without confirmation, or cancel all running background tasks.
Why use it?
It lets you stop work that is taking too long, was requested by mistake, or is no longer useful before it finishes.

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/data-wise/claude-plugins/task-cancel
Clone the repo
git clone --depth 1 https://github.com/Data-Wise/claude-plugins
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,229 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 $0.00000 $0.02229
Opus 5 $0.00000 $0.01115
Sonnet 5 $0.00000 $0.00446
Haiku 4.5 $0.00000 $0.00223

Measured yesterday against content hash 0e55c3c4bcc5, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

task-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 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.

workflow/commands/task-cancel.md · 470 lines

How it starts

The opening of the file, as written. The whole thing — 470 lines — stays where its author put it; the contents beside it link to each section on GitHub.

/task-cancel - Cancel Background Task

Cancel a running background task.

Purpose

Stop execution of background tasks from:

  • /workflow:brainstorm --background
  • /workflow:refine (option 2: background)
  • Any command with background delegation

Use when:

  • Task is taking too long
  • Realized you asked the wrong question
  • Want to try a different approach
  • Made a mistake in the prompt

Usage

/workflow:task-cancel <task_id>           # Cancel specific task
/workflow:task-cancel <task_id> --force   # Force cancel without confirmation
/workflow:task-cancel --all               # Cancel all running tasks

When invoked:

Cancel Specific Task

/workflow:task-cancel abc123

Output:

CANCEL BACKGROUND TASK
════════════════════════════════════════════════════════════

Task ID: abc123
Command: /workflow:brainstorm "improve test coverage"
Status: 🔄 Running
Started: 2 minutes ago
Estimated completion: ~1 minute remaining

────────────────────────────────────────────────────────────
⚠️  CONFIRM CANCELLATION

Are you sure you want to cancel this task?

Progress will be lost and the task cannot be resumed.

────────────────────────────────────────────────────────────

Confirm? (y/n)
>

If user confirms (y):

✅ Task cancelled: abc123

The task has been stopped and removed from the queue.

────────────────────────────────────────────────────────────
💡 NEXT STEPS:

Retry with different approach:
  /workflow:brainstorm "improve test coverage" --wait

Try interactive mode:
  /workflow:brainstorm

Check remaining tasks:
  /workflow:task-status

If user declines (n):

❌ Cancellation aborted

Task abc123 is still running.

Check status:
  /workflow:task-status abc123

Implementation:

  1. Look up task by ID
  2. Verify it's currently running
  3. Show confirmation prompt
  4. If confirmed, use KillShell or appropriate tool to stop task
  5. Update task registry with "cancelled" status
  6. Clean up any partial outputs
  7. Show next steps

Read the full file on GitHub · 470 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 · 470 lines · 0 tokens per session scan A 0e55c3c4bcc5

Subscribe to this mod's changes

task-cancel is a command published in the GitHub repository Data-Wise/claude-plugins (7 stars, last pushed 6d ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 2,229 tokens. 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.