incremental-implementation

incremental-implementation is a skill for Claude Code, Codex from momentmaker/kaijutsu. It costs 67 tokens per session (1,430 once invoked), scanned A, original, MIT.

A way to build a large feature as a series of small, usable changes. Each vertical slice covers the parts needed for one narrow capability and can be checked by continuous integration, the system that runs automated tests and checks.

In plain words
What is it for?
It is for implementing features in stages, organizing multi-change work, using feature flags, and keeping each change ready to merge.
Why use it?
Big-bang changes are difficult to review, test, and safely merge. Smaller slices make progress visible and keep each change independently deliverable.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: mentions subagents.

Good fit It is for implementing features in stages, organizing multi-change work, using feature flags, and keeping each change ready to merge.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/momentmaker/kaijutsu/incremental-implementation
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.

Any agent
npx skills add momentmaker/kaijutsu --skill incremental-implementation
Clone the repo
git clone --depth 1 https://github.com/momentmaker/kaijutsu

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 incremental-implementation

README.md
[![agentmods](https://agentmods.dev/badge/skills/momentmaker/kaijutsu/incremental-implementation.svg)](https://agentmods.dev/skills/momentmaker/kaijutsu/incremental-implementation)
Your own site
<a href="https://agentmods.dev/skills/momentmaker/kaijutsu/incremental-implementation"><img src="https://agentmods.dev/badge/skills/momentmaker/kaijutsu/incremental-implementation.svg" alt="Measured on agentmods" height="20"></a>
Per session 67 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,430 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00067 $0.01430
Opus 5 $0.00034 $0.00715
Sonnet 5 $0.00013 $0.00286
Haiku 4.5 $0.00007 $0.00143

Measured 7d ago against content hash 76f8e5af052d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

incremental-implementation 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 7d 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/core/incremental-implementation/SKILL.md · 103 lines

How it starts

The opening of the file, as written. The whole thing — 103 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Incremental Implementation

Adapted from addyosmani/agent-skills under the MIT License. Copyright (c) Addy Osmani. Per-slice two-stage review pattern + continuous-execution rule adapted from obra/superpowers/skills/subagent-driven-development under MIT.

The principle: every PR is mergeable on its own. No "wait for the next one" merges. No multi-week branches. Vertical = touches every layer (UI / API / DB / tests) for one narrow capability rather than completing one layer fully before moving to the next.

When to invoke

  • A spec or plan is ready and the user is about to start coding
  • The user says "this should be a multi-PR change"
  • A change exceeds 500 LOC or touches >5 files

Process

Step 1: Confirm a slice plan exists

If planning-and-task-breakdown produced a list of tasks, use that. Otherwise produce a slice plan now: 3-7 vertical slices, each ≤500 LOC, each with its own acceptance criteria.

Step 2: Pick the first slice

Hardest invariant first if possible (proves the design); easiest first if morale is needed (early win).

Step 3: Implement behind a feature flag

if (featureFlags.kaijutsuV2) { /* new path */ } else { /* old path */ }

The flag defaults OFF in main. Old behavior is preserved. New behavior ships when the flag flips.

Step 4: Tests + green CI

Every slice ends with: passing unit tests for the new code, no regression in existing tests, lint clean, type-check clean. If CI is red, the slice isn't done.

Step 5: Per-slice two-stage review chain

A slice is NOT complete after the implementer says "done". Run two reviews in order; only after BOTH pass does the slice get marked shippable.

Stage A — Spec compliance review. Dispatch a fresh subagent (clean context, no implementation history) with:

  • The slice's declared acceptance criteria from the plan
  • The slice's diff (git diff <base>..<head>)
  • One question: "Does this diff satisfy every acceptance criterion? Pass / fail per criterion + reasons."

Read the full file on GitHub · 103 lines

Files

What ships with it

2 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. 7d ago First seen · 103 lines · 67 tokens per session scan A 76f8e5af052d

Subscribe to this mod's changes

incremental-implementation is a skill published in the GitHub repository momentmaker/kaijutsu (3 stars, last pushed 2mo ago), licensed MIT. It adds 67 tokens to every session and 1,430 once invoked, about $0.0003 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 2026-08-31.