implement_plan

implement_plan is a skill for Claude Code, Codex from adrielp/ai-engineering-harness. It costs 18 tokens per session (701 once invoked), scanned A, original, Apache-2.0.

A process for carrying out an approved technical plan stored in a project's thoughts/plans folder. It reads the plan and related ticket and then applies the planned changes phase by phase.

In plain words
What is it for?
Use it when you already have an implementation plan and want the planned work carried out. It is suited to multi-step changes with supporting tickets or research notes.
Why use it?
It keeps implementation connected to the decisions and success checks recorded in the plan. It also tracks completed plan items so progress is visible.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/adrielp/ai-engineering-harness/implement_plan
Any agent
npx skills add adrielp/ai-engineering-harness --skill implement_plan
Clone the repo
git clone --depth 1 https://github.com/adrielp/ai-engineering-harness

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for implement_plan

README.md
[![agentmods](https://agentmods.dev/badge/skills/adrielp/ai-engineering-harness/implement_plan.svg)](https://agentmods.dev/skills/adrielp/ai-engineering-harness/implement_plan)
Your own site
<a href="https://agentmods.dev/skills/adrielp/ai-engineering-harness/implement_plan"><img src="https://agentmods.dev/badge/skills/adrielp/ai-engineering-harness/implement_plan.svg" alt="Measured on agentmods" height="20"></a>
Per session 18 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 701 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00018 $0.00701
Opus 5 $0.00009 $0.00351
Sonnet 5 $0.00004 $0.00140
Haiku 4.5 $0.00002 $0.00070

Measured 3d ago against content hash 9e4622ccc42a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

implement_plan scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

claude/skills/implement_plan/SKILL.md · 90 lines

How it starts

The opening of the file, as written. The whole thing — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Implement Plan

You are tasked with implementing an approved technical plan from thoughts/plans/. These plans contain phases with specific changes and success criteria.

Directory Structure:

  • thoughts/tickets/ - Original feature requests and task descriptions
  • thoughts/plans/ - Implementation plans (the files you'll be executing)
  • thoughts/research/ - Supporting research and investigation notes

Getting Started

When given a plan path:

  • Read the plan completely and check for any existing checkmarks (- [x])
  • Read the original ticket and all files mentioned in the plan
  • Read files fully - never use limit/offset parameters
  • Create a todo list to track your progress
  • Start implementing if you understand what needs to be done

If no plan path provided, ask for one.

Implementation Philosophy

Plans are carefully designed, but reality can be messy. Your job is to:

  • Follow the plan's intent while adapting to what you find
  • Implement each phase fully before moving to the next
  • Verify your work makes sense in the broader codebase context
  • Update checkboxes in the plan as you complete sections

If you encounter a mismatch:

  • STOP and present the issue clearly:
    Issue in Phase [N]:
    Expected: [what the plan says]
    Found: [actual situation]
    Why this matters: [explanation]
    
    How should I proceed?
    

Verification Approach

After implementing a phase:

1. Run Success Criteria Checks

Use technology-appropriate commands:

Node.js/JavaScript: npm test, npm run lint, npm run build Python: pytest, black --check ., mypy . Go: go test ./..., golangci-lint run, go build Rust: cargo test, cargo clippy, cargo build Make-based: make test, make lint, make build

2. Fix Issues and Update Progress

  • Address any failures before moving to the next phase
  • Update checkboxes in the plan file using the Edit tool
  • Update your TodoWrite list

If You Get Stuck

  1. Investigate First - Read all relevant code completely
  2. Use Sub-tasks for targeted help:
    • codebase-locator: Find specific files
    • codebase-analyzer: Understand how code works
    • codebase-pattern-finder: Find similar implementations
  3. Present Issues Clearly - Don't guess, ask for clarification

Read the full file on GitHub · 90 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 3d ago First seen · 90 lines · 18 tokens per session scan A 9e4622ccc42a

Subscribe to this mod's changes

implement_plan is a skill published in the GitHub repository adrielp/ai-engineering-harness (20 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 18 tokens to every session and 701 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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