fork-terminal

A tool for opening additional terminal sessions to run coding agents or command-line tasks in parallel. It can use separate Git worktrees, which are independent working directories for branches.

In plain words
What is it for?
Use it to run Claude Code, Codex CLI, Gemini CLI, or shell commands in another terminal, optionally in an isolated worktree.
Why use it?
It separates concurrent work so experiments or changes do not interfere with the main terminal session. It also selects different command-line tools and model sizes based on the request.

Skill for Claude CodeCodex

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/thrownlemon/claude-code-plugins/fork-terminal
Any agent
npx skills add ThrownLemon/claude-code-plugins --skill fork-terminal
Clone the repo
git clone --depth 1 https://github.com/ThrownLemon/claude-code-plugins

Made for: Claude Code, Codex.

Per session 28 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,236 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 $0.00028 $0.03236
Opus 5 $0.00014 $0.01618
Sonnet 5 $0.00006 $0.00647
Haiku 4.5 $0.00003 $0.00324

Measured yesterday against content hash aa807a4decba, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade C, and why

fork-terminal 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.

The scan reads SKILL.md. This mod also ships 7 executable files (tools/coordination.py, tools/fork_terminal.py, tools/spawn_session.py, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Instruction-override phrasinghighPrompt injection

Text telling the model to disregard its earlier instructions or safety rules is the shape of a prompt injection, whoever wrote it.

> **Security Warning (opt-in only)**: The `--dangerously-*` flags and `-y -p` (yolo headless) mode bypass safety prompts. Only add them when you explicitly need autonomous/unattended execution in a trusted environment.
plugins/fork-terminal/skills/fork-terminal/SKILL.md · 377 lines

How it starts

The opening of the file, as written. The whole thing — 377 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Fork Terminal Skill

This skill enables forking terminal sessions to new windows using various AI coding tools or raw CLI commands.

Supported Tools

Tool Trigger Pattern Default Model
Claude Code "fork terminal use claude code..." opus (bare alias, auto-tracks latest)
Codex CLI "fork terminal use codex..." gpt-5.2-codex
Gemini CLI "fork terminal use gemini..." gemini-2.5-pro
Raw CLI "fork terminal run..." N/A

Model Modifiers

  • fast: Use lighter/faster models (haiku, codex-mini, flash)
  • heavy: Use most capable models (opus, codex-max, gemini-pro)

How to Execute

  1. Identify the tool from the user's request
  2. Read the appropriate cookbook for execution details
  3. Execute fork_terminal(command) using the Python tool

Tool Selection

Match the user's language against these patterns:

  • "fork terminal use claude code to..." → Use cookbook/claude-code.md
  • "fork terminal use codex to..." → Use cookbook/codex-cli.md
  • "fork terminal use gemini to..." → Use cookbook/gemini-cli.md
  • "fork terminal run..." → Use cookbook/cli-command.md

Execution Steps

For AI Coding Tools (Claude Code, Codex, Gemini)

  1. Read the corresponding cookbook file to get model variables and command format
  2. Determine model based on modifier (fast/heavy/default)
  3. If the user requests "with summary" or context handoff:
    • Use the template in prompts/fork_summary_user_prompt.md
    • Fill in conversation history summary
    • Include the next user request
  4. Execute via: python3 ${CLAUDE_PLUGIN_ROOT}/skills/fork-terminal/tools/fork_terminal.py "<full_command>"

For Raw CLI Commands

  1. Parse the command from the user's request
  2. Run <command> --help first to understand options (if needed)
  3. Execute via: python3 ${CLAUDE_PLUGIN_ROOT}/skills/fork-terminal/tools/fork_terminal.py "<command>"

Example Commands

Default (interactive) — no bypass flags:

Read the full file on GitHub · 377 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 · 377 lines · 28 tokens per session scan C aa807a4decba

Subscribe to this mod's changes

fork-terminal is a skill published in the GitHub repository ThrownLemon/claude-code-plugins (2 stars, last pushed 2mo ago), licensed MIT. It adds 28 tokens to every session and 3,236 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it C with 1 finding (instruction-override phrasing). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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