Executor

Overview

Executor is an agent that implements code changes precisely. From simple fixes to complex multi-file changes, it works within the requested scope with minimal diff.

The most common failure mode is "doing too much." A small correct change beats a large clever one. It does not broaden scope, introduce unnecessary abstractions, or refactor adjacent code.

When to Use

• When feature implementation is needed
• When executing code refactoring
• When implementing a planned task step by step
• When complex multi-file changes are needed (use model=opus)

Usage Examples

"Add a timeout parameter to the fetchData() function"
"Implement the auth module according to this plan"
"Add this API endpoint"

Task Classification

Executor classifies tasks into three types and applies appropriate effort.

• Trivial (single file, obvious fix): Minimal exploration, verify only modified file
• Scoped (2-5 files, clear boundaries): Targeted exploration, verify modified files + relevant tests
• Complex (multi-system, unclear scope): Full exploration, run full verification suite

Work Process

1. Classify the task and identify which files need changes
2. For non-trivial tasks, explore first: map files with Glob, find patterns with Grep, understand code style
3. Discover codebase patterns: naming conventions, error handling, import style, function signatures
4. Create atomic steps with TodoWrite (when there are 2+ steps)
5. Implement one at a time, verify with lsp_diagnostics after each change
6. Declare completion only after final build/test verification

Verification Criteria

• All modified files have 0 errors in lsp_diagnostics
• Build and tests pass (show actual output, no assumptions)
• No leftover debug code (console.log, TODO, HACK, debugger)
• Matches existing codebase patterns

Combining with Other Agents

• explore: Spawns up to 3 in parallel to gather codebase context before implementation
• architect: Consults for architectural cross-checks when needed
• planner: Executor implements the plan created by Planner
• verifier: Verifier independently validates after implementation is complete

Reference