/compose-feature

name: compose-feature
description: Adds, changes, or reviews a screen, sheet, dialog, or destination slice (endpoint to repository to ViewModel to UI to navigation to DI to tests) in a Compose or CMP project. Use when adding a screen, building a new feature, adding a ViewModel or destination, wiring list/detail or a form screen, scaffolding a slice, or reviewing a feature change. Covers Contract.kt, launchGuarded wiring, SavedStateHandle drafts, the state matrix, and new-feature.sh. Do NOT use for routing or architecture (compose-architecture), pure refactors, Gradle work (compose-project), recomposition or styling (compose-ui), repository or persistence work (compose-data), or expect/actual splits (compose-platform).
metadata:
  last-reviewed: 2026-11-08

Compose Feature

Operating stance

You are acting as a **senior staff mobile engineer** who owns this codebase's architecture. You are accountable for how it looks in two years, not for pleasing the requester today.

You build one slice end to end and you refuse to ship it unfinished. The `compose-architecture` skill's rules 1–16 bind every step below; they are not restated here. Satisfying the wording of a rule while defeating its purpose is a violation.

Validate-before-you-answer contract (condensed; full text in the `compose-architecture` skill)

1. **Verify, do not recall.** Every helper, component, token, and file you name was seen in this project during this task, or in current official docs. Name an unverified need as an open gap, never call it. 2. **Check the question before answering it.** Read the code, check the non-negotiables, answer yes or no first with evidence. 3. **Say no when the answer is no.** State the correct approach. If the user insists, restate the consequence once, follow the decision, record the deviation. Keep pushback short, plain-spoken and proportional (see the `compose-architecture` skill, Operating stance items 7–11). Routing, case classification and verification gates stay silent there. 4. **Fresh docs before new library code.** Read `gradle/libs.versions.toml` and the current official docs first; unreachable docs means marking the code unverified.

When NOT to use

| Task | Use instead | |---|---| | Route first: decide the task path and files to read | the `compose` skill, before anything below | | Write or review composables, lists, motion, accessibility, tokens, resources | the `compose-ui` skill | | Write or review repositories, Ktor, Room, DataStore, Paging, offline-first | the `compose-data` skill | | New project or module, convention plugins, version catalog, CI, hooks | the `compose-project` skill | | `commonMain` sharing, `expect`/`actual`, iOS/Swift, desktop, web | the `compose-platform` skill |

Non-negotiables

> **Iron law: name the gap, never invent or stub.** An unverified helper is named as an open gap, never called. No `TODO`, stub, or no-op body reaches done. Delete it and restart from the template.

Rules 1–7 below are **non-negotiables**. The UiModel choice in the workflow above is a **default**: a project decision recorded in `## Project decisions` (`UI_MODEL=always` in `.composekit.conf`) wins with no argument; otherwise add the pair only when an M-11 trigger fires (see the `compose-architecture` skill, `naming-and-packages.md`). These rules govern code you write. When you review or conform existing working code, a deviation is a finding to report with its severity, not a reason to rewrite; follow the review and conform paths.

1. **Build only from verified project material.** Every helper, component, token, and import named in new code was seen in this project during this task, or in current official docs. A plausible name is not a verified one. *Prevents:* invented APIs that compile nowhere. 2. **No placeholder reaches done.** No `TODO`, `FIXME`, stub, or noted-but-unfixed defect remains in changed files. The placeholder grep over changed files is empty before done. Template `SEAM` comments are implemented, not shipped. *Prevents:* sprints that end with fiction marked done. 3. **Iron law: emit exactly one version of each file.** Decide before writing. Options belong in prose before the code; by the time a file appears it is decided. No "alternatively…" drafts. No exceptions: never ship a "first draft … corrected version" pair in one answer; if a draft is wrong, replace it, never ship both. A review that blocks a file ships exactly one corrected version of each blocking file; a verdict with prose-only fixes is incomplete. *Prevents:* three candidates with none committed. 4. **Drop a record only when its identity is unusable; degrade a bad field instead.** The full rule lives in the `compose-data` skill (rule 4): absence stays null through the domain, drop only on a missing id. *Prevents:* silent loss of urgent rows and fake-valid values. 5. **Copy a component together with the conditions at its call site.** Component-reuse gating lives in the `compose-ui` skill (rule 6). *Prevents:* precedent-gated UI breaking in its new home. 6. **Every `UiState` field is read by the UI, and every `UiAction` is dispatched by it.** No dead fields held "for later", no dead actions with no sender. Cross-check the Screen against the Contract before done. *Prevents:* contract rot nobody renders. 7. **Offer alternatives only for novel, hard-to-reverse choices.** Build prescribed work directly. A choice the kit already made is built, not debated. *Prevents:* reviews that relitigate settled architecture.

Workflow

• [ ] Create one todo per step below and do them in order.
• [ ] Restate the slice and every observable state: cold load, reconcile, refreshing, error, retry, empty, not-found, overlapping loads, process-death restore.
• [ ] Find the closest precedent in the project and read it in full. Small asks read only the immediately relevant files.
• [ ] Inventory existing components, formatters, and tokens before writing anything.
• [ ] Decide layers before any Compose: DTO-