Modify existing feature code across all affected layers — domain models, data, presentation, tests, and fakes. Use when changing behavior, adding fields, or enhancing existing features.
Installation
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Modify existing feature code across all affected layers — domain models, data, presentation, tests, and fakes. Use when changing behavior, adding fields, or enhancing existing features.
Update
Apply a change to existing feature code, keeping all layers in sync.
Parameters: feature name (optional if spec provides it)
Context (optional)
The user may provide additional context in three ways — all are optional:
Bare — just the feature name and a short description of the change.
@file reference — e.g., /update @specs/order-cart-total.md. The CLI resolves the file and includes its content. Extract feature name, affected layers, model changes, UI changes, and test impact from the spec. Template: .agents/templates/change-spec.md.
Inline description — free text describing the change. Extract whatever is provided and apply it across all affected layers.
Pre-flight: Grill the Spec
When the user provides a spec via @file, scan it for unresolved markers before scaffolding (see the grill-me skill for the full marker list): <!-- TODO --> placeholders, empty - [ ] AC items, empty required header fields, raw template placeholder prose, ... table cells, or unconfirmed reverse-spec presumptions (presumably / appears to). If any are present, stop and run /grill-me @{spec} first, then resume this skill.
The conversion skills (/ac-to-spec, /reverse-spec) grill inline before producing output, so a marker-laden spec usually means the spec was hand-authored from a template or has gone stale. Skip the pre-flight only if the user explicitly says "skip the grill" — in that case, surface unresolved markers as // TODO comments in the generated code and call them out in the final summary.
If the requested change touches more than 3 modules (e.g., api/domain + impl/data + impl/presentation + iOS, or multiple features), dispatch one Explore agent (or equivalent in your tool) BEFORE step 1 below. Sequential Read + grep calls to map the same surface are this skill's most common context drain — one round-trip replaces ~10 reads.
Recommended prompt template:
Map the affected surface for an update to feature `{feature}`. Specifically:
- Read `features/{feature}/AGENTS.md` and report the current Key Types table.
- Find every consumer of the types/methods being changed: {list types here}.
Search .kt, .swift, .gradle.kts, and AGENTS.md files.
- Identify every test fake or test fixture referencing the affected types.
- Note any iOS-side files in `iosApp/iosApp/Features/{Name}/` that import
the affected Kotlin types.
Report a punch list of files with the type of touch each needs.
See .agents/standards/ways-of-working.md → "When to Spawn Subagents" for the canonical trigger table and anti-patterns. Skip the dispatch for single-layer or ≤3-module changes — direct Read / Edit is faster there.
Design system & adaptive layout: .agents/standards/design-system.md
Steps
1. Understand the Current State
Read the feature's AGENTS.md for business context and key types
Read the specific files being changed to understand current behavior
Identify all layers affected by the change
2. Plan the Change
Map the requested change to concrete file modifications across layers. The codebase is dual-platform (Android Compose / iOS SwiftUI), so an "Android only" change to a Kotlin module almost always implies a sibling SwiftUI change in iosApp/. Audit both platforms before declaring the layer set.
Layer
When to touch
What changes
api/domain
Model shape changes, new/changed use case signatures
Cross-cutting SwiftUI primitives (sibling to core:presentation)
Shared SwiftUI views — WebView, future loading/error states
iosApp/iosApp/{Akamai,Circuit,Harness,Theme}/
Cross-cutting iOS infra mirroring a Kotlin core: module
Swift bridges, theme, navigation glue
iosApp/project.yml
New top-level folder under iosApp/iosApp/, new SPM package, new test plan, target config changes
XcodeGen project spec — regenerate via xcodegen after edits
test/
Changed abstractions need updated fakes
Fake classes
core:presentation (commonMain)
New Compose extension over a Compose-free core API
@Composable extensions like rememberFlag, collectAsState
core:presentation (androidMain)
New cross-cutting Android Compose UI primitive
Standalone Composables (e.g., WebViewContent) — pair with iOS sibling
Android ↔ iOS parity checklist
When a change touches a feature's UI or any cross-cutting presentation primitive, walk this checklist before proceeding:
Kotlin presenter / state / events — impl/presentation/commonMain changes apply to BOTH platforms automatically. No iOS-specific work needed for state shape changes alone.
iOS UI — iosApp/iosApp/Features/{Name}/{Feature}View.swift (SwiftUI). Updated to consume new state fields, render new UI elements, and dispatch new events via the KMP-NativeCoroutines-bridged presenter.
iOS navigation glue — iosApp/iosApp/Circuit/ if new navigation patterns (FlowScreen, ProtectedScreen, deep links) are involved.
iOS test plan membership — if new SwiftUI files need test coverage, confirm they're picked up by the relevant test plan (UnitTests, UIComponentTests, NavIntTests, E2ETests) via the targets in iosApp/project.yml.
Cross-cutting primitives — if you added a Composable to core:presentation/androidMain, add the SwiftUI sibling under iosApp/iosApp/Presentation/{Concept}/ and document the symmetric API. The two implementations should expose the same conceptual params (in their native idiom) so consumer features look symmetric.
iosApp/project.yml regeneration — if a new top-level folder under iosApp/iosApp/ was added, or files were added that XcodeGen doesn't auto-pick (rare; the default path: iosApp glob handles most cases), run xcodegen (or xcodegen generate) so iosApp.xcodeproj/project.pbxproj reflects the new file membership. Without this, SourceKit reports false-positive "module not found" / "type not in scope" errors and the file isn't built.
Android-only or iOS-only by design? If the change is intentionally one-platform (e.g., Android-only feature flag debug surface, iOS-only widget extension), document the asymmetry in the relevant AGENTS.md so future contributors don't think parity is missing by accident.
3. Apply Changes Top-Down
Work from domain outward to maintain compilation at each step:
api/domain — update models and use case signatures
impl/domain — update use case implementations and repository interfaces
impl/data — update DTOs, mappers, data sources, repository impls
iOS SwiftUI — update iosApp/iosApp/Features/{Name}/ views to consume new state, render new fields, dispatch new events. Cross-cutting primitives go under iosApp/iosApp/Presentation/.
iosApp/project.yml — only edit if a new top-level folder was added under iosApp/iosApp/, a new SPM package was introduced, or test-plan membership changed. After editing, run xcodegen to regenerate iosApp.xcodeproj. Default path-glob membership picks up new files in existing folders without project.yml edits.
test/ — update fakes to match changed abstractions
Tests — update existing tests (Kotlin Kotest unit + iOS Swift Testing unit + UI component robots on both platforms), add new test scenarios for new behavior. Each platform has its own test layer; don't skip iOS UI tests just because Android UI tests pass.
4. Sync Fakes and Test Defaults
Every changed abstract use case or model must have its fake updated:
FakeGet{Feature}Content — update DEFAULT companion value
FakeGet{Feature}Content — update emit() parameter types if model changed
Add new fake methods if new interactor methods were added
5. Update AGENTS.md
If the change affects the feature's key types, cross-feature dependencies, or documented patterns, update features/{name}/AGENTS.md to reflect the new state.
Key Rules
Never break compilation mid-change — update types before updating consumers
Keep all layers in sync — if a model field is added, it must flow through DTO → mapper → repository → use case → presenter → Android UI → iOS SwiftUI → tests → fakes
Both platforms are first-class — every UI-touching change must be applied to BOTH the Android Compose layer (impl/presentation/androidMain) AND the iOS SwiftUI layer (iosApp/iosApp/Features/{Name}/ or iosApp/iosApp/Presentation/ for cross-cutting primitives). A "we'll do iOS later" stance silently breaks parity. If the change is intentionally one-platform, document the asymmetry in the relevant AGENTS.md
Cross-cutting primitives are split-paradigm — Android Compose primitives belong in core:presentation/androidMain; the iOS SwiftUI sibling lives under iosApp/iosApp/Presentation/{Concept}/. APIs should be conceptually symmetric per primitive but adopt each platform's idioms (Composable + state holder vs UIViewRepresentable + @Binding). Do NOT introduce Compose-MP-iOS rendering for one-off primitives — iOS stays on SwiftUI
iosApp/project.yml is the iOS source of truth — when adding new top-level folders under iosApp/iosApp/, new SPM packages, or new test-plan members, edit project.yml and regenerate iosApp.xcodeproj via xcodegen. SourceKit "module not found" / "type not in scope" errors on freshly-added files almost always mean the project hasn't been regenerated yet
Preserve existing test coverage — update existing tests on both platforms to cover changed behavior, add new tests for new behavior
Don't expand scope — only change what the spec/description asks for
Events stay sealed class — not sealed interface (iOS interop)
Presenters use CenterPost interactors — never call repositories directly
Post-Change Verification — MANDATORY
Work is NEVER complete until verification passes. Run the verify skill to validate all changes. It will:
Detect which modules were affected
Run lint, unit tests, and architecture checks scoped to those modules
Catch naming violations, missing annotations, type mismatches, and test failures
If ANY check fails, fix the issue and re-run. Do not declare the task complete until verification passes.
iOS-specific verification reminders
verify covers Kotlin (Detekt + Kotest + Konsist + Android build). It does NOT exhaustively cover iOS — make sure the iOS side is also verified when iOS files were touched:
SwiftLint runs as part of verify, but the Swift compile + Xcode build do not. Run xcodebuild build -scheme iOSApp -destination 'platform=iOS Simulator,name=iPhone 17 Pro' (or use the mcp__xcode__BuildProject tool) to confirm the iOS app still compiles after SwiftUI edits
iOS unit tests — if behavior changes touched logic exercised by iosAppTests/Unit/, run xcodebuild test … -testPlan UnitTests
iOS UI component tests — if SwiftUI views changed, run xcodebuild test … -testPlan UIComponentTests
Harmonize architecture tests — swift test --package-path iosApp/ArchitectureCheck covers iOS-side conventions; run when iOS folder structure or SwiftUI organization changed
xcodegen regeneration — if iosApp/project.yml was edited or new top-level folders/files were added, the project.pbxproj must be regenerated. Without this, the new files will not compile and Xcode will report stale errors
