Subagent

Implementation Executor

Execute implementation tasks systematically following the task plan with

Type: Subagent
Repository: athola/claude-night-market
GitHub stars: 339
License: MIT
Repo last updated: Sep 24, 2026
Source file: plugins/spec-kit/agents/implementation-executor.md
Model: sonnet

What Implementation Executor is

Implementation Executor is a subagent published in the athola/claude-night-market repository on GitHub, which has about 339 stars. The repository describes itself as: “23 Claude Code plugins: TDD enforcement hooks, git/PR workflows, spec-driven development, code review, project lifecycle, fix-from-error, maintenance automation, context optimization, research, and multi-LLM delegation. 186 skills, 128 commands, 54 agents.”

A subagent is a specialist assistant that Claude can hand part of a task to. It is a markdown file whose frontmatter sets a name, a description that tells Claude when to delegate, and optionally the tools and model it may use; the body becomes the subagent's own system prompt.

Because a subagent works in its own context, it keeps the main conversation focused: Claude can send a narrow job, such as a review or a specialised analysis, to Implementation Executor and get back a compact result.

How to install Implementation Executor

Claude Code

Download implementation-executor.md from the repository.
Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control.
Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Claude Cowork

Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent.
Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

New to extending Cowork? Our plugins guide and Customize guide explain how skills, plugins, and connectors fit together.

Inside the source file

An excerpt from plugins/spec-kit/agents/implementation-executor.md, shared under the repository's MIT license. Read the full file on GitHub.

Executes implementation tasks systematically following the task plan.

Capabilities

Phase-by-phase task execution
TDD approach (tests before implementation)
Dependency-aware sequencing
Parallel task coordination
Progress tracking with checkmarks
Error handling and recovery

Execution Strategy

Pre-Implementation

Validate all checklists are complete
Load implementation context (tasks.md, plan.md, data-model.md)
Verify project setup (ignore files, dependencies)

Task Execution

Process tasks by phase order
Respect sequential dependencies
Execute NONCONFLICTING parallel tasks [P] concurrently (DEFAULT)

Verify all tasks pass conflict checks (files, state, dependencies, paths, outputs)
Invoke ALL nonconflicting Task tools in SINGLE response

Follow TDD: write tests first when applicable

Post-Task

Mark completed tasks with [X]
Run relevant tests
Report progress
Handle failures gracefully

Project Setup Verification

Automatically creates/verifies:

.gitignore for detected tech stack
.dockerignore if Docker present
Tool-specific ignore files

Progress Tracking

Updates tasks.md with completion status
Reports after each phase
Halts on critical errors
Continues parallel tasks on individual failures

Error Handling

Clear error messages with context
Suggestions for resolution
Option to skip or retry failed tasks

Usage

Provide the feature directory:

Execute implementation for .specify/specs/feature-name/

Before you install

Read the whole file first. Skills, commands, and subagents are instructions Claude will follow, so make sure they match what you want.
Check which tools, scripts, or MCP servers it uses. Local servers and scripts run with your permissions.
Try it in a test project or a copy of your files before pointing it at real work.
Pin the version you tested, and review changes before updating.
Watch for instructions that fetch web content or run shell commands; those are where prompt injection risks start. See our prompt injection guide.

FAQ

What is Implementation Executor?

Implementation Executor is a subagent for Claude Code and Claude Cowork from the athola/claude-night-market repository on GitHub. Execute implementation tasks systematically following the task plan with

How do I install Implementation Executor in Claude Code?

Download implementation-executor.md from the repository. Save it to ~/.claude/agents/ to use it in every project, or to .claude/agents/ inside one project to share it through version control. Claude Code watches these folders, so the subagent is usually available right away. Ask Claude to use it by name, or @-mention it to make sure it runs.

Can I use Implementation Executor in Claude Cowork?

Cowork loads subagents through plugins. If the repository is packaged as a plugin marketplace, add it under Customize → Plugins → Add marketplace and install the plugin that contains this subagent. Otherwise, bundle the file into your own plugin's agents/ folder and upload it from Customize → Plugins.

Is Implementation Executor safe to install?

It is a third-party community resource, not reviewed by Anthropic or this site. Read the source file first, check which tools and connectors it uses, and install only from sources you trust.

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Listing data comes from the public GitHub repository and was last checked in September 2026. Excerpts are © their authors and shared under MIT. This directory is independent and not affiliated with Anthropic or the resource's authors.