Canonical skill for initializing and maintaining projects following the APP (AI-First Programming Paradigm) protocol.

Install

mkdir -p .claude/skills/app && curl -L -o skill.zip "https://agentskills.codes/api/skills/download/10761" && unzip -o skill.zip -d .claude/skills/app && rm skill.zip

Installs to .claude/skills/app

Activation

This is the description your AI agent reads to decide when to run this skill — the better it matches your request, the more reliably it fires.

use when setting up APP projects, adding host apps, creating or updating Cases, introducing packages, classifying shared code across cases/packages/core/shared, maintaining case .us.md artifacts, validating APP grammar, reviewing structural drift, and adapting existing projects incrementally with the canonical /app workflow
325 chars✓ has a “when” triggerlonger than Claude Code's old 250-char listing cap (fine on current versions)
Intermediate

Key capabilities

  • Inspect project topology and classify artifacts
  • Set up new APP projects with canonical layers
  • Add host apps like backend, portal, or agent
  • Create and update Case artifacts
  • Validate APP grammar and host runtime rules
  • Detect architectural drift in Cases and hosts

How it works

The skill enforces a strict operational profile by guiding the agent through an inspect, specify, create, validate, and review workflow. It requires the presence of a spec.md file to serve as the normative protocol reference.

Inputs & outputs

You give it
Project directory and task description
You get back
Project structure updates and validated Case artifacts

When to use app

  • Setup new APP project
  • Create new host app
  • Validate architectural grammar

About this skill

/app — Canonical Operational Skill for APP

This is the active PRD revision of the canonical /app skill. It keeps the operational content of the previous revision while reducing repetition and improving scanability.

Revision Metadata

What This Skill Does

  • inspect an APP project and explain its topology
  • set up a new APP project with canonical layers and the first host app
  • add a new host app such as backend, portal, agent, worker, or lambdas
  • create a new Case such as usuario_criar
  • implement or revise domain, api, ui, web, mobile, stream, and agentic surfaces
  • introduce packages/ and expose them correctly through host registries
  • classify whether a new artifact belongs in cases/, packages/, core/shared/, or requires protocol evolution
  • validate APP grammar and host runtime rules
  • detect architectural drift in Cases and hosts
  • adapt an existing project to APP incrementally when requested
  • create or update <case>.us.md when semantics, contracts, or composition change

If you do not know APP yet, this skill should guide you through the canonical workflow instead of assuming prior protocol knowledge.

APP is the protocol layer of the AI-First Programming Paradigm. /app is the canonical skill for applying that protocol in real projects.

Example Prompts

  • Use /app to inspect this repository.
  • Set up a new APP project using /app.
  • Add an agent host app using /app.
  • Create case usuario_criar using /app.
  • Introduce packages/ for shared HTTP clients using /app.
  • Adapt this existing project to APP incrementally using /app.
  • Implement the api surface for usuario_criar using /app.
  • Validate this repository with APP grammar.
  • Review drift in this project using /app.
  • Create usuario_criar with domain, api, and usuario_criar.us.md.

1. Identity

Positioning

  • executable workflow for APP engineering
  • architecture-aware implementation and review guide
  • operational lint for APP grammar and runtime rules

Scope

  • operates with the adjacent installed spec.md as its normative protocol reference
  • operationalizes the current APP protocol version
  • may be stricter than baseline APP conformance
  • must not contradict canonical APP grammar

Authority

  • for the agent: this document is the operational source of truth
  • for project maintenance: protocol changes must be reflected here
  • if implementation drifts from this document, report the drift and keep following this grammar until a human resolves it

2. /app Profile

APP defines baseline protocol grammar. /app defines a stricter operational profile for agents working on APP projects.

TopicAPP baseline/app profile
test()strongly recommendedrequired on every surface created or edited by the agent
<case>.us.mdoptional support artifactrequired for new Cases, new surfaces, and semantic changes
workflowfreeinspect → specify → create/implement → validate → review
validationmay be partialmust happen before task closure
agentic completenessagentic optional; app-level agentic host formalized in current specwhen the task requires agentic at Case or app level, the full formal definition is mandatory; partial or placeholder agentic layers are non-conformant in /app
subagentsoutside protocol scoperequired when supported and parallel work is useful

Core Rules

  • start unknown work with inspect
  • on every /app turn, read this SKILL.md and the adjacent installed spec.md before acting; if spec.md is missing, report incomplete skill installation or drift
  • keep handler() thin and free of business logic
  • create or update <case>.us.md when semantics change
  • add or update test() on every touched surface
  • if the task requires the agentic layer, define it completely according to the current normative contract; never leave a partial agentic host or surface behind
  • validate and review before closing the task

3. APP Model

Canonical Layers

packages/ → core/ → cases/ → apps/
LayerRole
packages/shared project code exposed by the host through ctx.packages
core/protocol contracts, base classes, types, integration interfaces
cases/capabilities; shareable business logic lives here
apps/hosts; select Cases, providers, packages, runtime, and deployment model

Import Rules

RelationshipRule
cases/core/allowed
apps/cases/allowed through registry
apps/packages/allowed
cases/packages/ direct importforbidden; use ctx.packages
Case A → Case B direct importforbidden; use ctx.cases
cases/apps/forbidden

Structural Tasks Supported by /app

TaskCanonical result
new APP projectcreate canonical layers, first host app, first registry, and first Case path
new host appadd apps/<app>/app.ts and apps/<app>/registry.ts with only needed _cases, _providers, _packages
new packageadd shared project code under packages/ and expose it per app through _packages / ctx.packages
new core/shared/ artifactadd only if it is a protocol-level contract or shared structural shape
new canonical surfacestop normal implementation flow and treat as protocol evolution
existing-project adoptioncarve out APP-managed areas incrementally; do not force a full rewrite unless requested

4. Case Model

A Case is one cohesive capability organized inside its own folder.

Naming and Layout

  • canonical name: <entity>_<verb>
  • folder: cases/<domain>/<case>/
  • surface file: <case>.<surface>.case.<ext>
  • support artifact: <case>.us.md

<case>.us.md

The canonical support artifact is <case>.us.md. It records operational intent without replacing domain.case.ts.

Required in /app when:

  • a new Case is created
  • a new surface is added
  • Case semantics change
  • cross-case composition is introduced
  • recovery, policy, or agentic contract changes materially

Optional only when:

  • the change is purely editorial
  • the change is purely technical and does not alter semantics, contracts, or behavior

5. Surface Grammar

Implement only the surfaces the task needs.

5.1 Summary Matrix

SurfaceFileGoalRequired in /appOptionalKey Rules
domain<case>.domain.case.tspure semantics, invariants, validation, schemas, examplescaseName(), description(), inputSchema(), outputSchema(), test()validate, invariants, valueObjects, enums, examples, definitionno I/O; consumed manually by other su

Content truncated.

When not to use it

  • When the project does not follow the canonical APP protocol
  • When the task involves partial or placeholder agentic layers

Prerequisites

spec.md

Limitations

  • Requires test() on every surface created or edited
  • Must not contradict canonical APP grammar
  • Partial agentic layers are non-conformant

How it compares

Unlike manual project management, this skill enforces a specific grammar and requires test creation for every surface touched.

Compared to similar skills

app side by side with the closest alternatives in the catalog.

SkillInstallsUpdatedSafetyDifficulty
app (this skill)04moNo flagsIntermediate
agent-pseudocode16moNo flagsIntermediate
phase-2-convention04moReviewBeginner
phase-1-schema05moNo flagsBeginner

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