Spawn Ralph - Parallel Agent Execution

What

Spawn isolated Ralph agents (claude -p) for parallel subtasks. Each Ralph runs in its own process with fresh context.

When

• •You have independent subtasks that can run in parallel
• •You want to fan-out work then collect results
• •Subtasks don't need to share context with each other

How

Single Ralph (blocking)

cd /path/to/workdir && claude -p "Your task description here"

Single Ralph (background, non-blocking)

Use Bash with run_in_background: true:

Bash(command="cd /workdir && claude -p 'Implement feature X'", run_in_background=true)

Multiple Parallel Ralphs

Spawn multiple in ONE message with parallel Bash calls:

Bash(command="cd /dir1 && claude -p 'Task 1: Research API patterns'", run_in_background=true)
Bash(command="cd /dir2 && claude -p 'Task 2: Write unit tests'", run_in_background=true)
Bash(command="cd /dir3 && claude -p 'Task 3: Update documentation'", run_in_background=true)

Restrict Tools

claude -p "task" --allowedTools "Bash,Read,Write,Glob,Grep"
claude -p "task" --disallowedTools "Edit,WebSearch"

Check Status

Use TaskOutput(task_id="...", block=false) with the ID from background Bash.

Pattern: Fan-out / Fan-in

1. •Fan-out: Spawn N Ralphs with background Bash (parallel tool calls in one message)
2. •Continue or Wait: Do your own work OR poll TaskOutput
3. •Fan-in: Collect results via TaskOutput when done
4. •Synthesize: Merge/combine Ralph outputs

Key Points

• •Each Ralph = isolated process, own context, no pollution
• •Ralph exits when task complete or if it gets stuck
• •Use descriptive task prompts - Ralph has no prior context
• •Output captured via TaskOutput tool
• •Don't spawn too many - each is a full Claude process