Subagent Batching

Subagent Batching

Patterns for parallel subagent execution. Use your judgment on batch sizes based on task complexity.

When to Parallelize

Parallelize when:

• Processing multiple independent items (PRs, issues, files)
• Tasks have no dependencies between items
• Each item can succeed or fail independently

Don't parallelize when:

• Later items depend on earlier results
• Shared resources could cause conflicts
• You need to aggregate results before proceeding

Launch Pattern

Launch subagents in a single message with multiple Task tool calls. Don't launch sequentially.

# Correct: ONE message with multiple Task calls
Task 1: Process item A
Task 2: Process item B
Task 3: Process item C
# All launch simultaneously

Batching for Large Sets

For many items, batch them and validate between batches:

1. Launch a batch of subagents in parallel (single message)
2. Wait for all to complete using TaskOutput with block=true
3. Validate results before proceeding
4. Start next batch after validation

Subagent Prompts

Give each subagent focused context:

• Clear task description
• Relevant identifiers and locations
• Expected output format
• Success criteria

Error Handling

• One failure shouldn't block the rest
• Mark failed items for human review
• Continue processing remaining items
• Provide summary of successes and failures

Reporting

After completion, summarize:

• Total items processed
• Successes with brief descriptions
• Failures with reasons
• Any required follow-up actions