build-an-app

name	build-an-app
description	Walk through the full process of building a digital health app — from planning to implementation.

Build an App

Walk a user through building a digital health app from start to finish. This skill orchestrates the other skills in this repository — it figures out what the user needs, runs the right planning skills, and hands off to implementation.

When to Use

Use this skill when a user wants to:

• build a new digital health app from scratch
• figure out where to start on a health app idea
• go from idea to running code with guidance at each step

Do not use this skill if the user wants to run a specific skill directly (e.g., they ask for FHIR data model design). Let them use that skill on its own.

Working Style

You are a conversational guide. Keep it lightweight — don't front-load questions. Listen to what the user says, infer what you can, and only ask about what you can't figure out. Move at their pace.

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Step 1: Listen

Start with one open question:

"What do you want to build?"

Let the user describe their idea naturally. They might give you one sentence or three paragraphs — either is fine.

From their answer, look for signals about:

Signal	What it tells you
Mentions a specific disease, condition, or clinical workflow	Health data and possibly FHIR are involved
Mentions a research study, trial, or enrollment	Study planning is needed
Mentions patient data, PHI, HIPAA, or regulatory concerns	Compliance planning is needed
Mentions HealthKit, vitals, wearables, or sensor data	Health data modeling is needed
Mentions EHR, Epic, SMART on FHIR, or interoperability	FHIR data model design is needed
Mentions they already have a repo or project	Skip platform selection
Mentions they already have designs or wireframes	UX planning may be lighter or skippable
Says "I don't know where to start" or describes a vague idea	Needs-finding would help

If you can't tell whether the app involves health data, connects to clinical systems, or is part of a study, ask one follow-up question that covers the gaps. For example:

"Will this app collect or store any health data, and is it tied to a research study?"

Do not ask more than one follow-up. If something is still ambiguous, include the relevant skill in your proposed plan — the user can remove it.

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Step 2: Propose a Plan

Based on what you heard, assemble a plan from the available skills. Every skill is conditional — include only what the user's situation calls for.

Skill selection guide

Skill	Include when
biodesign-needs-finding	User is unsure about the problem, has a vague idea, or asks for help scoping
spezi-platform-selection	User does not already have a project repo — runs last to choose React Native or Apple-native, clone the matching template, and move the planning briefs into it
digital-health-ux-planning	User does not already have designs or wireframes
health-data-model-planning	App stores or processes health data (vitals, assessments, patient records)
fhir-data-model-design	App needs FHIR interoperability or connects to EHRs
digital-health-compliance-planning	App handles PHI or has regulatory concerns
digital-health-study-planning	App is part of a research study with enrollment and assessments
app-build-planner	Always — produces the implementation plan that drives the build

Present the plan as a short numbered list with one line per skill explaining what it does. Then ask:

"Does this look right, or would you add or remove anything?"

Let the user adjust before proceeding.

Picking up where they left off

If the user already has a project, check for existing planning documents in docs/planning/. Skip any skill whose output already exists. If they already have docs/implementation-plan.md, skip straight to building.

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Step 3: Run Each Skill

Work through the selected skills in the order below. For each one:

1. Tell the user what the skill does and what it will produce (one sentence)
2. Read the skill's SKILL.md and follow its instructions
3. After completion, verify the output was saved to the correct path
4. Briefly summarize what was produced before moving on

Execution order and output paths

All planning skills run before spezi-platform-selection, so the user is not committed to a platform until the plan is in hand.

Run skills in this order (skipping any that were not selected):

Skill	Output Path	What it Produces
biodesign-needs-finding	docs/planning/need-statement.md	Need statement: problem, population, outcome
digital-health-ux-planning	docs/planning/ux-brief.md	User journeys, onboarding, workflows
digital-health-study-planning	docs/planning/study-brief.md	Study protocol, enrollment, assessments
health-data-model-planning	docs/planning/data-model-brief.md	Entities, relationships, FHIR recommendations
fhir-data-model-design	docs/planning/fhir-data-model.md	FHIR resources, terminology, relationships
digital-health-compliance-planning	docs/planning/compliance-brief.md	Privacy domains, controls, required decisions
app-build-planner	docs/implementation-plan.md	Milestone-based build sequence
spezi-platform-selection	Cloned template repository	Working project directory with template code; planning briefs moved into the cloned repo

spezi-platform-selection runs last (when the user is ready to build). It uses the planning briefs to recommend a platform, clones the matching Spezi template, and moves the existing docs/planning/ and docs/implementation-plan.md into the cloned repo so the coding agent has full context.

Between each skill, ask: "Ready to move on, or do you want to adjust anything?"

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Step 4: Start Building

After app-build-planner saves docs/implementation-plan.md, summarize everything that was produced — only list documents that were actually created:

Here's what we have:

Project: [cloned template path]

Planning documents:
  [list only the docs that were created]

Implementation plan:
  docs/implementation-plan.md
  [N] milestones, starting with [Milestone 1 name]

Ready to start building Milestone 1?

If the user says yes, read docs/implementation-plan.md, find Milestone 1, and begin implementing it.

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Guardrails

• Every skill is optional except app-build-planner. Include skills based on what the user described, not a fixed checklist.
• Do not front-load questions. Start with "What do you want to build?" and ask at most one follow-up.
• When in doubt, include it in the plan. If you're not sure whether a skill is needed, propose it and let the user remove it. It's easier to drop a step than to discover you missed one.
• Respect the user's pace. Let them review and adjust after each skill completes. Do not auto-advance without checking.
• Handle the "skip to coding" case. If planning docs already exist, acknowledge them and pick up where they left off.
• Each skill is interactive. When you read a skill's SKILL.md and follow its instructions, the user should participate — answer questions, review outputs, provide input. Do not simulate their answers.