implement-spec

A workflow for completing a detailed software specification in small, reviewable code changes. Each pass is committed and the next pass continues until the specification is complete.

In plain words
What is it for?
For building multi-step features, coordinating independent work, maintaining checkpoints, and tracking global TODOs and required checks.
Why use it?
It prevents long implementation work from losing track of unfinished parts, stale plans, cleanup, or handoffs.

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/dzhng/duet-agent/implement-spec
Any agent
npx skills add dzhng/duet-agent --skill implement-spec
Clone the repo
git clone --depth 1 https://github.com/dzhng/duet-agent

Made for: Claude Code, Codex.

Per session 41 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,357 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 98% copy Near-identical to another mod 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 $0.00041 $0.03357
Opus 5 $0.00020 $0.01679
Sonnet 5 $0.00008 $0.00671
Haiku 4.5 $0.00004 $0.00336

Measured 3d ago against content hash a54b5ffcae40, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

implement-spec 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.

Origin

This is a copy

98% identical to implement-spec — 4 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.agents/skills/implement-spec/SKILL.md · 235 lines

How it starts

The opening of the file, as written. The whole thing — 235 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Implement Spec

Build the active spec to completion, one reviewable pass at a time. The spec is the source of truth, but the architecture is allowed to improve when the code teaches you the plan is stale.

A pass (usually one slice) is a commit checkpoint, not a stopping point. The job is the whole spec — every slice, every global TODO — not the first green commit. Finishing a pass means starting the next one, not handing back to the user. Only stop when the spec is fully implemented (or a genuine blocker needs a decision only the user can make).

Work in parallel wherever the graph allows. Do not walk the ladder one slice at a time when slices are independent. Read the spec's dependency graph as a wavefront and delegate independent passes to subagents that run concurrently (see Rules) — you orchestrate and integrate; only serialize what genuinely depends on prior work.

Workflow

  1. Read the repo README, the spec README, and the next slice before editing. Load any skills named by the spec. Identify the current pickup point, global TODOs, required gates, and what must stay green. If a multi-slice spec lacks a live handoff prompt, add one before the first pass ends.
  2. Reconcile the plan with the current code. If the slice would preserve a development-only shim, duplicated type, weak wrapper, or obsolete path, replace it with the simpler architecture and update the spec handoff.
  3. Implement one coherent pass: usually one slice, one vertical checkpoint, or one architecture correction. Keep the review surface small enough to audit.
  4. Verify the actual contract. For behavior changes, run the focused unit tests first; for browser-visible work, use the real browser/harness and inspect screenshots so the subject is framed and readable, not merely nonblank. A visual CHANGE carries two extra proofs before you claim it: a byte/pixel diff against the pre-change baseline on the production route (static checks and re-anchored assertions all pass on a no-op — a palette pass once shipped "verified" while the production frame was byte-identical), and an unprimed screenshot-critique — at the user's reported framing when the pass answers their visual bug report — before declaring it fixed; the implementer's eyes are primed by the fix and repeatedly pass what fresh eyes catch. Never weaken an existing default gate or repin a failing contract without proving the old contract is wrong.
  5. Review the change list and clean up after every pass, before committing. Read git status/git diff --stat line by line and account for every path: one-off probes, shot scripts, scratch files, nohup.out, ad-hoc screenshot dirs, and SPIKE/debug notes never enter a commit — scratch stays out of the tree; review evidence belongs in the spec's assets/; anything else gets deleted. A file you can't name the durable purpose of does not ship. Delegated agents leak these; the integrating reviewer re-checks the merged tree with the same eye.

Read the full file on GitHub · 235 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 · 235 lines · 41 tokens per session scan A a54b5ffcae40

Subscribe to this mod's changes

implement-spec is a skill published in the GitHub repository dzhng/duet-agent (42 stars, last pushed 3d ago), licensed Apache-2.0. It adds 41 tokens to every session and 3,357 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 98% identical to implement-spec, differing in 4 lines, and is treated as a copy.

Related

Other skills, from other repositories