Spawn Swarm

Parallel agents for parallel work.

The Pattern

Single message → Multiple Task calls → Parallel execution → Collected results

One message with 5-20 Task tool invocations. All run simultaneously. Results come back together.

Swarm Templates

Bug Hunt (5-10 agents)

"Find bugs across the codebase"

Spawn per module:
- auth-agent
- payment-agent
- user-agent
- api-agent
- data-agent

PR Review (3-4 agents)

"Review PR #123"

Spawn specialists:
- security-reviewer
- performance-reviewer
- style-reviewer
- test-coverage-reviewer

Feature Build (4 agents)

"Build [feature]"

Spawn workers:
- ui-agent
- logic-agent
- test-agent
- docs-agent

Codebase Exploration (5 agents)

"Understand how [thing] works"

Spawn explorers:
- entry-point-finder
- flow-tracer
- dependency-mapper
- pattern-identifier
- edge-case-hunter

Invocation

Single Message, Multiple Tasks

[Task: Search auth/ for security issues]
[Task: Search payment/ for security issues]
[Task: Search api/ for security issues]
[Task: Search data/ for security issues]
[Task: Search user/ for security issues]

All in ONE message.

Use run_in_background

For long-running work:
run_in_background: true

Continue other work.
Check results with TaskOutput later.

Agent Types

Explore (subagent_type: Explore)

Fast file/code search
Pattern finding
Codebase questions

General (subagent_type: general-purpose)

Multi-step implementation
Complex changes
Autonomous work

Specialists

code-reviewer
debugger
security-reviewer
performance-reviewer

Sizing Guidelines

Token Efficiency

Agents Have Narrow Context

Main conversation: Full codebase
Each agent: Only its target area

5 agents searching 5 areas:
- Same tokens as 1 agent doing all 5
- 5x faster
- Each has focused context

Agent Summary Pattern

Agent explores extensively.
Returns: "Found issue in auth.swift:142"

You get 1-line summary.
Not the full exploration trace.

Anti-Patterns

❌ Don’t

- Spawn for simple reads (just use Read tool)
- Spawn with dependencies (race conditions)
- Spawn 50 agents (chaos)
- Wait on each before spawning next

✓ Do

- One message, all agents
- Independent targets
- 5-20 agents max
- Background for long work

Example Prompt

Spawn a bug-hunting swarm:

1. Search src/auth/ for security vulnerabilities
2. Search src/payment/ for data handling issues
3. Search src/api/ for input validation bugs
4. Search src/user/ for permission issues
5. Search src/data/ for race conditions

Return findings ranked by severity.

Use when: Any parallel work opportunity