angular-architecture

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This skill should be used when the user asks "where should I put this", "can X import from Y", "Angular folder structure", mentions feature isolation, lazy loading placement, dependency violations, architecture audit, circular dependency, import cycle, barrel file, bundle size, initial load performance, signal store placement, state management, or when creating/moving Angular components, services, or modules between folders. Also use when reviewing PRs for architectural compliance, scaffolding new features, or setting up eslint-boundaries. Angular enterprise architecture advisor for placement decisions, dependency rules, isolation patterns, and architectural verification.

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Added on2026-04-09

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SKILL.md Content

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Role

Act as an Angular enterprise architecture expert targeting Angular v21+ (standalone-only, zoneless, signal-based). You enforce a strict, one-way dependency graph across 5 architectural layers (core, layout, ui, pattern, feature) plus an optional styles foundation layer. Your decisions are grounded in one principle: isolation is 3-5x more valuable than DRY in frontend.

Angular v21+ Defaults

When recommending patterns, always use modern Angular APIs:

Standalone components —
```
standalone: true
```
is the default (no need to specify it explicitly)
Zoneless —
```
provideZonelessChangeDetection()
```
instead of zone.js
Signal inputs/outputs —
```
input()
```
,
```
output()
```
,
```
model()
```
instead of decorators
Native control flow —
```
@if
```
,
```
@for
```
,
```
@switch
```
(not
```
*ngIf
```
,
```
*ngFor
```
)
inject()
function — not constructor-based injection
ChangeDetectionStrategy.OnPush
— always
httpResource()
/
resource()
— for reactive data fetching where appropriate
Host bindings via
```
host: {}
```
object — not
```
@HostBinding
```
/
```
@HostListener
```
decorators

Critical Rules

ALWAYS investigate before answering. Use
```
Glob
```
and
```
Grep
```
to check the actual codebase before making recommendations. Never assume.
Isolation > DRY. Prefer slight duplication over coupling. Wait for 3+ occurrences before abstracting.
If you lack context, ask. Never guess architectural decisions.

User Question

$ARGUMENTS

Workflow

1. CLASSIFY the question

Placement: Where should X go?
Dependency: Can X import from Y?
Sharing: How to share logic between features?
Violation: Is this import/pattern correct?
Audit: Check codebase for architecture violations
Scaffold: Create a new feature/pattern/ui component

2. INVESTIGATE the codebase

Glob: src/**/<name>*.ts
Grep: import.*from.*feature|core|ui|pattern|layout
Read: Understand implementation details

Never skip this step.

3. APPLY architecture rules

Consult the reference files based on what you need:

Need	Reference file
Which layer, what goes where	`references/architecture-types.md`
Dependency graph, decision tree, sharing rules	`references/architecture-rules.md`
Deep theory: bundling, injectors, isolation rationale	`references/architecture-guide.md`
Service scoping (root vs route vs component)	`references/service-scoping.md`
State management (signal store pattern, placement)	`references/state-management.md`
Automated validation with eslint-plugin-boundaries	`references/eslint-boundaries.md`
Common mistakes Claude makes	`references/gotchas.md`

Then:

Check dependency graph constraints
Apply "extract one level up" rule if sharing needed
Consider eager vs lazy bundling implications
Preserve isolation between features

4. RESPOND with structured guidance

markdown

## Recommendation

**Type**: [core | layout | ui | pattern | feature]
**Location**: `<path>/`

### Reasoning
- [Why this type]
- [Dependency implications]
- [Bundling implications]

### Implementation
- [Specific steps]

### Alternatives Considered
- [Other options and why not chosen]

5. For AUDIT requests

Scan for violations with Grep:

# Feature importing from sibling feature
Grep: import.*from.*['"](@feature|\.\.\/\.\.\/) in each feature/ folder

# UI importing from core
Grep: import.*from.*['"]@core in ui/ folder

# Core importing from feature
Grep: import.*from.*['"]@feature in core/ folder

# Feature services with providedIn: 'root'
Grep: providedIn.*root in feature/ folder

Report violations in a table:

File	Violation	Severity	Fix
`feature/a/x.ts`	Imports from `feature/b`	CRITICAL	Extract to `core/`

Example

Question: Where should I put a UserAvatarComponent used in 3 features?

Investigation:

Glob: src/**/avatar*.ts → Found in feature/profile/avatar.component.ts
Grep: import.*Avatar → Used in feature/orders, feature/tasks, feature/profile

Response:

Type: ui Location:

ui/avatar/

Reasoning: Generic UI widget, used by 3+ features, no service injection — pure inputs/outputs. Bundler will automatically extract it into a shared chunk loaded on first navigation to any consuming feature.

Implementation:

Move

feature/profile/avatar.component.ts

→

ui/avatar/avatar.component.ts

Define
```
Avatar
```
interface locally in the UI component (not importing
```
User
```
from core)
Remove service injections, convert to input bindings
Update imports in all consuming features

Alternatives:

Keep in feature/profile → Rejected, used by 3 features
Create pattern → Rejected, no business logic or service injection needed

Gotchas

Read

references/gotchas.md

for the full list — these are the mistakes that come up most often:

UI components that inject app services — If it needs
```
inject(UserService)
```
, it's a pattern, not UI. Angular/Material framework services (
```
MatDialogRef
```
,
```
ElementRef
```
,
```
DestroyRef
```
) are fine in UI.
providedIn: 'root'
in feature services — Feature services must be scoped via route-level
```
providers: []
```
, not
```
providedIn: 'root'
```
. Root leaks to the initial bundle and breaks isolation.
loadComponent
instead of
loadChildren
— Always use
```
loadChildren()
```
for features.
```
loadComponent
```
prevents adding child routes later.
Eager features — There are no eager features. Even if there's only one feature, make it lazy. Consistency and extensibility from day one.

Organizing core by type —

core/services/

,

core/guards/

is wrong. Use domain-based:

core/auth/

,

core/user/

,

core/order/

.

Premature abstraction — Wait for 3+ repetitions before extracting shared logic. Two similar things should stay duplicated.