Fork Terminal Skill

Spawn new terminal windows to run AI agents or CLI commands in parallel sessions. Enables "out-of-loop" agentic coding where forked agents handle routine tasks independently.

Variables

# Feature Flags
enable_gemini_cli: false          # Set to true to enable Gemini CLI support
enable_raw_cli: true              # Enable raw CLI command execution
auto_context_handoff: true        # Automatically pass context summary
capture_output: true              # Save output to logs/forks/

# Defaults
default_model: sonnet             # haiku | sonnet | opus

# Model Mapping
model_haiku: claude-3-5-haiku-20241022
model_sonnet: claude-sonnet-4-20250514
model_opus: claude-opus-4-20250514

When to Use

Activate this skill when the user:

• Says "fork", "spawn agent", "run in new terminal", "delegate", "parallel"
• Wants to run Claude Code or Gemini in a separate session
• Needs parallel work on different tasks
• Mentions "new window", "background task", "separate agent"
• Wants to delegate routine tasks (bug fixes, tests, research)

Quick Reference (Natural Language)

User Says	What Happens
"Fork a Claude agent to [task]"	Spawn Claude Code agent with task
"Fork Gemini to [task]"	Spawn Gemini CLI (if enabled)
"Fork a raw terminal to run [command]"	Run CLI command in new terminal
"Show fork status"	Show running/completed tasks
"List all forked tasks"	List all tracked forks
"Kill fork [id]"	Terminate a running fork
"Kill all forks"	Terminate all running forks
"Fork a bugfix agent for [desc]"	Preset: spawn bugfix agent
"Fork a research agent to explore [topic]"	Preset: spawn research agent
"Fork to run tests"	Preset: run and fix tests
"Fork a review agent"	Preset: code review agent

Flags

All commands support these flags:

Flag	Purpose
--model haiku|sonnet|opus	Select model tier
--with-context	Pass condensed context summary to forked agent
--worktree	Create git worktree for isolation
--no-output	Don't capture output to logs
--skip-permissions	Add --dangerously-skip-permissions (trusted automation)
--new-window	Force new window instead of tab (Windows Terminal only)

Instructions

Step 1: Parse Request

Determine the fork type from user's message:

1. Check for preset names first:

   • "bugfix", "research", "tests", "review" → Route to preset handling
   • Read cookbook/presets.md for preset configuration

2. Determine fork type:

   • Mentions "claude", "code", or no specific CLI → Claude Code fork
   • Mentions "gemini" AND enable_gemini_cli=true → Gemini CLI fork
   • Mentions "raw", "cli", "command", "run" → Raw CLI fork
   • Mentions "status", "list", "kill" → Management command (no spawn)

3. Extract the task:

   • The task is whatever the user wants the forked agent to do
   • Be specific and actionable

Step 2: Handle Management Commands

If request is a management command (status, list, kill):

For "show fork status":

uv run tools/task_registry.py status

For "list forked tasks":

uv run tools/task_registry.py list

For "kill fork [id]":

uv run tools/task_registry.py update --id <id> --status failed --notes "Manually killed"

Note: This marks the task as failed but doesn't actually terminate the terminal. Inform user they may need to close the terminal manually.

For "kill all forks":

uv run tools/task_registry.py clear --status running

Skip remaining steps for management commands.

Step 3: Parse Flags

Extract flags from the request:

If user says...	Flag
"--model X" or "use X model"	--model X
"--with-context" or "pass context" or "include context"	--with-context
"--worktree" or "use worktree" or "isolate"	--worktree
"--no-output" or "no logs"	--no-output
"skip permissions" or "trusted"	--skip-permissions

Step 4: Context Handoff (if --with-context)

If context handoff is requested:

1. Read the fork summary user prompt: Read prompts/fork_summary_user_prompt.md to understand how to generate a summary.

2. Generate a condensed context summary: Following the prompt's instructions, create a summary including:

   • The delegated task (most important)
   • What you've been working on
   • Key files touched
   • Important decisions made
   • Current state/blockers

3. Save the context:

   uv run tools/context_builder.py --task "<delegated task>" --context "<background>" --files <file1> <file2>
   

4. Note the context file path for passing to fork_terminal.py

Step 5: Create Worktree (if --worktree)

If worktree isolation is requested:

1. Read worktree guide: Read cookbook/worktree-guide.md for patterns.

2. Create worktree:

   uv run tools/worktree_manager.py create --branch fork/<task-name> --task "<task>"
   

3. Note the worktree path - use it as the CWD for fork_terminal.py

Step 6: Execute Fork

Run the fork terminal script:

uv run tools/fork_terminal.py \
  --type <claude|gemini|raw> \
  --task "<task>" \
  --model <haiku|sonnet|opus> \
  --cwd "<working-directory>" \
  [--with-context <context-file>] \
  [--no-output] \
  [--skip-permissions]

Step 7: Register Task

The fork_terminal.py script returns a JSON result. Extract the task_id and register it:

uv run tools/task_registry.py add \
  --id <task_id> \
  --task "<task>" \
  --type <claude|gemini|raw> \
  --model <model> \
  --cwd "<cwd>" \
  --output-file "<output-file>" \
  [--context-file "<context-file>"] \
  [--preset "<preset-name>"]

Step 8: Confirm to User

Report back to the user:

1. Task ID for tracking
2. Command being executed
3. Output location if capturing
4. How to check status (say "show fork status")

Example confirmation:

Forked Claude Code agent (task: abc123)
- Task: Fix the null pointer in user.email validation
- Model: sonnet
- Working directory: C:\project
- Output: logs/forks/2024-12-27_fix-null-pointer_abc123.md

Say "show fork status" or "list forked tasks" to check progress.

Progressive Disclosure

If fork type is Claude Code:

Read cookbook/claude-code.md for Claude CLI flags, patterns, and best practices.

If fork type is Gemini CLI:

Read cookbook/gemini-cli.md for Gemini CLI usage. Note: Only available if enable_gemini_cli=true in variables.

If using a preset:

Read cookbook/presets.md and apply the matching preset configuration. Presets define model tier, context settings, and task templates.

If --worktree flag used:

Read cookbook/worktree-guide.md for worktree creation and management.

Error Handling

Error	Action
Windows Terminal not found	Fall back to PowerShell (automatic)
Task fails to spawn	Report error, don't register task
Output capture fails	Continue without capture, warn user
Git worktree creation fails	Abort, report error to user
Not in git repo (worktree)	Inform user worktree requires git repo
Gemini CLI requested but disabled	Inform user to enable in variables

Key Principles

From IndyDevDan's agentic coding philosophy:

1. Fresh context windows are essential - Forked agents start clean, avoiding context pollution
2. In-loop vs Out-of-loop - Complex work = in-loop (current session); routine tasks = out-of-loop (forked)
3. Simple solutions are better - Don't over-engineer the fork; let the agent figure things out
4. Eliminate confusion - Be specific about what the forked agent should do
5. There's no reason to manually fix small bugs when agents can handle them out-of-loop

Files Reference

File	Purpose
tools/fork_terminal.py	Core cross-platform terminal spawning
tools/task_registry.py	Track running/completed tasks
tools/context_builder.py	Build context handoff files
tools/worktree_manager.py	Git worktree management
prompts/fork_summary_user_prompt.md	How to generate context summary
prompts/fork-summary.md	Template forked agent receives
cookbook/claude-code.md	Claude CLI reference
cookbook/presets.md	Preset definitions
cookbook/worktree-guide.md	Worktree patterns
data/forked-tasks.json	Task registry (auto-created)
logs/forks/	Output logs from forked agents