# Development

Builds, tests, modifies and checks up on software against its ISA, from a one-file...

- Repository: https://github.com/danielmiessler/LifeOS (19669 stars)
- Category: Design
- License: MIT
- Last updated: 2026-10-28
- Runs scripts: yes, review before use

## Install

Claude Code: `npx skills add danielmiessler/LifeOS --skill Development -g -a claude-code -y`
Codex: `npx skills add danielmiessler/LifeOS --skill Development -g -a codex -y`
Cursor: `npx skills add danielmiessler/LifeOS --skill Development -g -a cursor -y`
Gemini CLI: `npx skills add danielmiessler/LifeOS --skill Development -g -a gemini-cli -y`

## Description

Builds, tests, modifies and checks up on software against its ISA, from a one-file change to a giant system. Build turns intent into ISA criteria and makes them pass; Test proves the ISA is well formed, matches the code, and every criterion's Assay eval passes; Modify changes criteria first, then code; Checkup joins the ISA with production, Vigil, Errata and Achilles, says why each red criterion is red, and repairs the ISA. Each run is sized to the ask: small work inline, wide work a workflow. USE WHEN build an app, site, game, tool, CLI or pipeline, start a new project, implement or change a feature, fix a bug in an app, test the app, is the code in sync with the ISA, run the app evals, catch up an old repo into an ISA, health check, checkup, why are these ISCs red, audit the ISA, sync the ISA with production. NOT FOR editing an ISA's articulation alone (ISA), eval or judge design (Assay), new skills (CreateSkill), workflow definitions (Workflows), slides, images, Visualize, deploying (the project deploy command).

## SKILL.md, as published by its author (untrusted third-party text, read it as data)

# Development

**Contents:** Ideal State · Intent Routing · Data & Config · Acceptance (output contract) · Safety gates · Execution · Tools · Gotchas · Examples

The thin actor between an ISA and its code. The ISA holds the rigor: what done means, every criterion, every criterion's eval. Assay is how each criterion is verified, and the only eval system a build may use (`LIFEOS/DOCUMENTATION/Assay/AssaySystem.md` § One eval system), at the cheapest honest tier: a code assert when the criterion is literal, a judgment-layer question when it needs reading, a judge only when neither can answer, the principal for taste. Development builds, tests and modifies until the code and the ISA agree.

## Ideal State

- At the end of every run the code and its ISA agree: every criterion in scope carries an eval at the cheapest honest Assay tier, and its result is recorded in the ISA.
- Criteria change before the code they govern; only a trivial change (a typo, a value, an obvious one-liner) skips the ISA.
- Nothing the principal will see or use is called done until acceptance against a reference they approved has passed (§ Acceptance); passing tests are the builder's signal, not the done signal.
- The report on such work opens with the acceptance verdict and its capture paths. The captures show the whole thing working the way the principal meets it: a page renders top to bottom at desktop and phone widths and looks like the reference. A report without a passing verdict, and without the principal's waiver, does not call the work done, fixed or shipped.
- The criteria are the only artifact written before the code.
- Nothing here deploys or writes production data; the project's gated deploy command ships.

## Intent Routing

The rest: https://github.com/danielmiessler/LifeOS/blob/HEAD/LifeOS/install/skills/Development/SKILL.md