implement

implement is a skill for Claude Code, Codex from ericrisco/rsc-harness. It costs 123 tokens per session (5,803 once invoked), scanned A, original, MIT.

A test-first implementation process for turning an approved software plan into working code. TDD means writing a failing test before writing the code that makes it pass.

In plain words
What is it for?
It is for implementing approved features with a red-green-refactor cycle, using the project's testing tools, and recording progress between tasks.
Why use it?
It helps developers build one planned task at a time while keeping progress, decisions, and test evidence visible.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions CLAUDE.md; mentions subagents; mentions Claude Code.

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/ericrisco/rsc-harness/implement
Any agent
npx skills add ericrisco/rsc-harness --skill implement
Clone the repo
git clone --depth 1 https://github.com/ericrisco/rsc-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

README.md
[![agentmods](https://agentmods.dev/badge/skills/ericrisco/rsc-harness/implement.svg)](https://agentmods.dev/skills/ericrisco/rsc-harness/implement)
Your own site
<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/implement"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/implement.svg" alt="Measured on agentmods" height="20"></a>
Per session 123 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,803 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 5.1 $0.00123 $0.05803
Opus 5 $0.00062 $0.02901
Sonnet 5 $0.00025 $0.01161
Haiku 4.5 $0.00012 $0.00580

Measured 2d ago against content hash 34be01180fb7, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

implement 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 2d 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.

skills/implement/SKILL.md · 388 lines

How it starts

The opening of the file, as written. The whole thing — 388 lines — stays where its author put it; the contents beside it link to each section on GitHub.

implement — turn the task list into tested code

You have a spec, a plan, and an ordered task list (from specifyplantasks), and the analyze gate has cleared. This skill does the building: it walks the tasks in order, writes each one test-first, stops to show its work after every task, and records the decisions it makes along the way. It is the intent → shipped code engine's hands — verify is the gate that comes after, not part of this skill.

This is a process skill. It owns the discipline (red → green → refactor, checkpoints, decision logging, constitution adherence). It does not own the test tooling — pytest fixtures, go test table-drivers, Vitest/Playwright, flutter test — those belong to the stack skill, and you call into them rather than reinventing them.

Before you write a line of code

Run this short gate. Skipping it is the most common way an implement session goes sideways. This gate is a hard refuse, not a checklist to feel good about: if it fails you stop and route back — you do not write feature code anyway.

  1. The spec + plan must exist AND be approved. Open the spec (02-DOCS/wiki/sdd/specs/<slug>.md), the plan (02-DOCS/wiki/sdd/plans/<slug>.md, which holds the task list), and the constitution (02-DOCS/wiki/sdd/constitution.md). If any is missing, you are not allowed to implement — route back: no spec → specify; no plan → plan; no task list inside the plan → tasks; unresolved analyze findings → resolve them first. If a spec/plan exists but the user has not actually seen and approved it, get that approval first. Never "start coding to discover the plan as you go", and never accept "just build it, skip the spec" on a non-trivial feature — name the gate in one friendly line and route to specify. (Only a true one-line, low-risk change earns a skip, and you say so.)
  2. Read the SDD runtime config. Open 02-DOCS/wiki/sdd/config.yaml. If it is missing on non-trivial work, stop and route to sdd-init. Use testing.strict_tdd, testing.commands.apply, testing.commands.verify, sdd.review_budget and sdd.registry_path. Do not choose a different test command from memory while config exists.
  3. Read the skill registry. Open .rsc/skill-registry.json if present. Select only the relevant stack/process skills for this task, then digest them into compact rules. If the registry is missing, run or recommend npx @ericrisco/rsc registry refresh and record the fallback.
  4. Read the accompaniment dial. Open 02-DOCS/wiki/harness/user-profile.md and read the technical + accompaniment level. It sets how loud you are at each checkpoint (see the dial table below). No profile yet → assume non-technical, narrate more, and ask before any irreversible step.
  5. Confirm isolation. Implementation happens on a feature branch or worktree, never directly on the default branch. If you are on main/master, stop and hand to worktrees before the first commit.
  6. Scan the tasks for independence. Mark which tasks share files/state and which are disjoint. Disjoint clusters are candidates for parallel; everything else runs in order.

Read the full file on GitHub · 388 lines

Files

What ships with it

6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 2d ago First seen · 388 lines · 123 tokens per session scan A 34be01180fb7

Subscribe to this mod's changes

implement is a skill published in the GitHub repository ericrisco/rsc-harness (64 stars, last pushed 3d ago), licensed MIT. It adds 123 tokens to every session and 5,803 once invoked, about $0.0006 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 2026-09-03.

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