AGENTS.md — Jetpack Compose Android app

A native Android app in Kotlin with declarative UI, one-way data flow and screenshot plus journey tests.

Setup and commands

• dev: ./gradlew installDebug
• lint: ./gradlew lint ktlintCheck detekt
• test: ./gradlew test connectedCheck
• build: ./gradlew bundleRelease
• install: ./gradlew dependencies

Project structure

• app/ — Application, navigation graph, dependency setup
• feature/<journey>/ — Screens and view models for one journey
• core/designsystem/ — Theme, tokens and design-skill components
• core/data/ — Repositories, network and database
• core/analytics/ — Event names from the experience skill

Code style

• Files: PascalCase.kt
• Tests: <Type>Test.kt; <Journey>JourneyTest.kt
• Branches: type/short-description
• Components: PascalCase composables named after the design-skill component

Code

• Prefer small, pure functions and explicit types at module boundaries. (Easier to test, review and change.)
• Composables are stateless; state is hoisted to the view model. (Previews and tests stay simple.)

Components

• Components read design tokens; no raw hex values, pixel sizes or font names in component code. (One token change restyles the product.)

Data

• Analytics events are object_action in snake_case and come from the experience skill’s measures. (Names stay consistent across teams and tools.)

Errors

• Every async action has loading, empty, error and success states, matching the experience skill. (Unhandled states are where users get stuck.)

Security

• Secrets never live in the repository; read them from the environment or a secret store. (A leaked key outlives the commit that removed it.)
• Validate every input on the server, even when the client already did. (Clients can be bypassed.)
• Web pages ship a Content-Security-Policy, HSTS, X-Frame-Options and nosniff. (Cheap protection against the most common attacks.)

Performance

• Use stable types and keys in lazy lists; check recomposition counts for list screens. (Keeps scrolling smooth.)

Accessibility

• Use native elements first; add ARIA only when no native element fits. (Native controls bring keyboard and screen-reader support for free.)
• Every interactive composable has a content description or visible label and a 48dp minimum touch target. (TalkBack users and platform guidance.)

Design and journeys

When a Celestial design skill is in use, write its tokens as Compose MaterialTheme in core/designsystem/Theme.kt, and build its components in core/designsystem/component with the same names and variants. Components read tokens only — no raw colours, sizes or font names.

When a Celestial experience skill is in use, give each journey one end-to-end test (happy path plus its error and empty states) and name analytics events object_action from its measures.

Testing and checks (must pass before a pull request)

Pull requests

• Branching: Short-lived branches; release branches per Play release.

Review checklist

• Correctness: does it do what the issue asks, including edge cases?
• Readability: could a new teammate change it safely?
• Architecture: is it in the right place, with the right boundaries?
• Security: inputs, secrets, permissions, dependencies
• Performance: budgets, queries, bundle size
• Tests fail when the code is broken (flip a condition and re-run)
• Screenshots attached for UI changes

Definition of done

• Acceptance criteria met and demoed on the preview link
• Tests added for new behaviour and every state
• Accessibility and performance gates green
• Analytics events named from the experience skill
• Docs or changelog updated when behaviour changes

Release

• Small pull requests (aim for under 400 changed lines)
• CI green before review
• Squash-merge to main; main is always deployable
• Every release has a written rollback path
• Internal track on every merge; staged rollout 10% → 50% → 100%

Incidents

• Halt the staged rollout; remote config flags to disable features

Generated from the Celestial engineering skill “Jetpack Compose Android app” (engineering core v1.0, checked 2026-10-25).