| name | code-organization |
| description | Enforce code organization principles - the "Directory X contains ONLY class type X" law, DDD naming patterns, type safety, SOLID, factory usage, and hardcoded config extraction to .env. Use when placing new classes, reviewing code structure, refactoring (moving, renaming, splitting classes), fixing CI failures that stem from structural or naming issues, or extracting hardcoded configuration values. |
Code Organization Skill
Profile keys consumed
architecture.source_root
architecture.bounded_contexts
architecture.shared_context
framework.name
framework.api_platform
framework.graphql
persistence.mapper
make.ci
make.psalm
make.deptrac
make.phpinsights
make.tests
quality.phpinsights.architecture
quality.phpinsights.style
quality.phpinsights.complexity
quality.deptrac_violations
quality.psalm_errors
Core Principle
Directory X contains ONLY class type X
This is the fundamental, stack-generic law of code organization. It holds
in every bounded context under architecture.source_root, regardless of
framework or persistence engine.
Context (Input)
- Creating new classes and determining the correct directory
- Moving classes to proper locations
- Reviewing code for organizational compliance
- Fixing organizational issues from code reviews
- Ensuring class names match their responsibilities
- Refactoring code structure (moving, renaming, splitting classes)
- Fixing CI failures that stem from structural/naming issues
- Extracting hardcoded config values (TTLs, timeouts, limits) to
.env
Task (Function)
Enforce strict code organization principles: proper directory structure,
DDD naming conventions, specific variable names, type safety, SOLID
principles, and PHP best practices.
Source paths follow the profile: classes live under
<architecture.source_root>/<Context>/ where <Context> is one of
architecture.bounded_contexts (or architecture.shared_context when
set). See DIRECTORY-STRUCTURE.md for the full
layer-by-layer placement reference.
Directory Type Classification
Classes MUST be in directories matching their type:
| Directory | Contains ONLY | Example |
|---|
Converter/ | Type converters | UlidTypeConverter |
Transformer/ | Data transformers (DB/serial) | CustomerToArrayTransformer |
Validator/ | Validation logic | UlidValidator |
Builder/ | Object builders | QueryBuilder |
Fixer/ | Data fixers/modifiers | DataFixer |
Factory/ | Object factories | CustomerFactory |
Resolver/ | Value resolvers | CustomerUpdateScalarResolver |
Serializer/ | Serializers/normalizers | CustomerNormalizer |
Formatter/ | Data formatters | CustomerNameFormatter |
Mapper/ | Data mappers | PathsMapper |
Provider/ | Data/service providers | TimestampProvider |
Processor/ | API state processors | CreateCustomerProcessor |
EventListener/ | Framework event listeners | QueryParameterValidationListener |
EventSubscriber/ | Event subscribers | SendEmailOnCustomerCreated |
Processor/ applies when framework.api_platform is set (not false);
GraphQL-specific directories (MutationInput/, GraphQL Resolver/)
apply when framework.graphql is true.
Directory Creation Guardrails
- NEVER create new directories autonomously — every new class-type
directory MUST follow a well-known software engineering pattern
(Factory, Builder, Processor, Validator, Provider, Resolver, etc.) AND
be explicitly requested/approved by the user. When in doubt, use an
existing directory.
- Do not invent ad-hoc class-type directories or suffixes. The following
are explicitly forbidden:
Applier/, Attacher/, Enricher/ — not well-known patterns
Augmenter/ — not a well-known pattern
Helper/, Util/, Manager/ — vague catch-all anti-patterns
Service/ — leads to anemic domain models; use specific pattern
names instead (Provider, Factory, Resolver, etc.)
- Any proposed new directory MUST be a well-known software engineering
pattern (e.g. Factory, Builder, Strategy, Observer, Adapter,
Decorator, Proxy, Iterator, Mediator, etc.) — not an invented
verb-noun.
- Use existing DDD/CQRS directory types and naming patterns from this
skill.
- Follow DDD and CQRS strictly — all class organization must align with
established DDD layers and CQRS patterns.
DDD Naming Patterns
By Layer and Type
| Layer | Class Type | Naming Pattern | Example |
|---|
| Domain | Entity | {EntityName}.php | Customer.php |
| Value Object | {ConceptName}.php | Email.php, Money.php |
| Domain Event | {Entity}{PastTenseAction}.php | CustomerCreated.php |
| Repository Iface | {Entity}RepositoryInterface.php | CustomerRepositoryInterface.php |
| Exception | {SpecificError}Exception.php | InvalidEmailException.php |
| Application | Command | {Action}{Entity}Command.php | CreateCustomerCommand.php |
| Command Handler | {Action}{Entity}Handler.php | CreateCustomerHandler.php |
| Event Subscriber | {Action}On{Event}.php | SendEmailOnCustomerCreated.php |
| DTO | {Entity}{Type}.php | CustomerInput.php |
| Processor | {Action}{Entity}Processor.php | CreateCustomerProcessor.php |
| Transformer | {From}To{To}Transformer.php | CustomerToArrayTransformer.php |
| Infrastructure | Repository | {Technology}{Entity}Repository.php | DoctrineCustomerRepository.php |
| Doctrine Type | {ConceptName}Type.php | UlidType.php |
| Bus Implementation | {Framework}{Type}Bus.php |
Directory Structure by Layer
<architecture.source_root>/<Context>/
├── Application/
│ ├── Command/ ← Commands
│ ├── CommandHandler/ ← Command Handlers
│ ├── EventSubscriber/ ← Event Subscribers
│ ├── DTO/ ← Data Transfer Objects
│ ├── Processor/ ← API state processors (framework.api_platform)
│ ├── Transformer/ ← Data Transformers
│ ├── Validator/ ← Validators
│ ├── Converter/ ← Type Converters
│ ├── Resolver/ ← Value Resolvers
│ ├── Factory/ ← Factories
│ ├── Builder/ ← Builders
│ ├── Formatter/ ← Formatters
│ └── MutationInput/ ← GraphQL Mutation Inputs (framework.graphql)
├── Domain/
│ ├── Entity/ ← Entities & Aggregates
│ ├── ValueObject/ ← Value Objects
│ ├── Event/ ← Domain Events
│ ├── Repository/ ← Repository Interfaces
│ └── Exception/ ← Domain Exceptions
└── Infrastructure/
├── Repository/ ← Repository Implementations
├── DoctrineType/ ← Custom Doctrine Types
├── EventSubscriber/ ← Infrastructure Event Subscribers
├── EventListener/ ← Framework Event Listeners
└── Bus/ ← Message Bus Implementations
<Context> is each entry of architecture.bounded_contexts; the shared
kernel (when architecture.shared_context is set) follows the same
layout.
Verification Checklist
When creating or reviewing a class, verify:
- ✅ Class Type Matches Directory (Directory X contains ONLY class type X)
- Example:
UlidValidator in Validator/, NOT Transformer/
- ✅ Class Name Follows DDD Pattern for its type
- ✅ Namespace Matches Directory Structure exactly
- ✅ Class Name Reflects Actual Functionality
- ✅ Correct Layer (Domain/Application/Infrastructure)
- ✅ Domain Layer Has NO Framework Imports (
framework.name
components, Doctrine, API Platform)
- ✅ Variable Names Are Specific (not vague)
- ✅
$typeConverter, $scalarResolver (specific)
- ❌
$converter, $resolver (too vague)
- ✅ Parameter Names Match Actual Types
- ✅
mixed $value when accepts any type
- ❌
string $binary when accepts mixed
- ✅ No "Helper" or "Util" Classes (extract specific responsibilities)
- ✅ No ad-hoc class-type suffixes/directories (
Applier,
Attacher, Enricher, Augmenter, Helper, Util, Manager,
Service)
- ✅ New directories are explicit and standard, not agent-invented —
must be explicitly approved by the user
PHP Best Practices
Required Patterns
- ✅ Constructor property promotion
- ✅ Inject ALL dependencies (no default instantiation)
- ✅ Use
readonly when appropriate
- ✅ Use
final for classes that shouldn't be extended
- ✅ No static methods (except named constructors like
create(), from())
Anti-Patterns (Forbidden)
Where the repository ships static-analysis architecture guards (Psalm
plugins, forbiddenFunctions), they enforce these rules under
architecture.source_root; treat the rules as binding even when no
automated guard exists.
- ❌ Helper/Util/Service/Manager classes - Extract specific
responsibilities;
Service leads to anemic domain models
- ❌ Non-standard pattern directories - No
Applier/, Attacher/,
Enricher/, Augmenter/ — use well-known patterns (Processor,
Transformer, Validator, Factory, etc.)
- ❌ Default instantiation in constructors - Inject dependencies
- ❌ Vague variable names - Be specific
- ❌ Namespace mismatches - Must match directory structure
- ❌ Ad-hoc directory/class type inventions - Use established
patterns only; NEVER create new directories without explicit user
approval
- ❌ Constructor defaults that instantiate collaborators - Inject
dependencies instead of using
new in __construct(...) defaults
- ❌ Direct
new of value objects that expose named constructors -
Use the named constructor ({ValueObject}::fromString()) in
production code
- ✅ Direct
new of normalizers inside custom Doctrine types -
Allowed because Doctrine types cannot use constructor DI
- ❌ Direct instantiation of guarded collections/events in production
code - Use dedicated factory classes (
{Object}CollectionFactory,
{Event}Factory)
- ❌ Plain
json_encode/json_decode - Use the framework serializer
(SerializerInterface for framework.name: symfony); tests are
excluded from this rule
- ❌ Untyped
array in method signatures - Always specify the
array's content type via docblock (list<string>,
array<string, int>) or use a typed collection class (custom Doctrine
type and collection-internal storage excluded)
- ❌ Bare
array, list, or iterable collections of domain
objects - Every domain object type that has a dedicated collection
class must use it, repo-wide under architecture.source_root.
Internal storage inside collection classes may still use array.
Upstream reference service: Psalm architecture guards enforce these
domain-type -> collection mappings repo-wide in src/ and require factory
classes (OAuthProviderCollectionFactory, SignInEventFactory,
SessionRevocationEventFactory, TwoFactorEventFactory,
RefreshTokenEventFactory) plus OAuthProvider::fromString():
OAuthProvider/OAuthProviderInterface -> OAuthProviderCollection
User/UserInterface -> UserCollection
RecoveryCode -> RecoveryCodeCollection
AuthSession -> AuthSessionCollection
PasswordResetTokenInterface -> PasswordResetTokenCollection
DomainEvent -> DomainEventCollection
Factory Pattern (Maintainability & Flexibility)
Avoid hardcoded new ClassName() in production source code — use
factory methods or Factory classes
Factory Methods on Value Objects
Value objects SHOULD provide static factory methods as named constructors:
$status = new CustomerStatus($value);
$status = CustomerStatus::fromString($value);
Factory methods (fromString(), fromArray(), create()) are the
preferred way to instantiate value objects outside of their own
class. The constructor remains public for use within named constructors
and tests.
Collections and domain events should follow a different rule in
production code: use dedicated Factory classes instead of adding static
convenience constructors just to avoid new.
When Factory Classes Are REQUIRED (Production Code)
- Objects with injected dependencies (timestamp providers, config, etc.)
- Objects requiring complex construction logic
- Objects needing different implementations per environment
- Objects created from external input (DTOs, metrics, etc.)
When Direct new Is ACCEPTABLE
- Inside factory methods and Factory classes (that's their purpose)
- In test code (simplicity over abstraction)
- For framework-required patterns (e.g.,
throw new InvalidArgumentException())
- Inside the value object's own named constructors
Factory Benefits
- ✅ Centralized object creation logic
- ✅ Easy to inject different implementations
- ✅ Configuration changes don't affect consumers
- ✅ Single place for validation/transformation
- ✅ Enables dependency injection for complex objects
Example: Bad vs Good
public function emit(BusinessMetric $metric): void
{
$timestamp = (int)(microtime(true) * 1000);
$payload = new MetricsPayload(
new MetricsMetadata($timestamp, new MetricConfig(...)),
new DimensionValueCollection(...),
new MetricValueCollection(...)
);
$this->logger->info($payload);
}
public function emit(BusinessMetric $metric): void
{
$payload = $this->payloadFactory->createFromMetric($metric);
$this->logger->info($payload);
}
Factory Naming Convention
{ObjectName}Factory - creates {ObjectName} instances
- Location: Same namespace as the object being created
- Example:
MetricsPayloadFactory creates MetricsPayload
Type Safety: Classes Over Arrays
Arrays are NOT allowed for collections that already have a dedicated
collection type. Use the collection class instead.
Arrays lack type safety and self-documentation. Use concrete classes
instead. CI guards (where present) block bare collections of guarded
domain types in production code, including iterable-based variants.
Array vs Class Comparison
| Pattern | Bad (Array) | Good (Class) |
|---|
| Configuration | ['endpoint' => 'X', 'operation' => 'Y'] | new EndpointOperationDimensions('X', 'Y') |
| Return data | return ['name' => $n, 'value' => $v] | return new MetricData($n, $v) |
| Method params | function emit(array $metrics) | function emit(MetricCollection $metrics) |
| Events data | ['type' => 'created', 'id' => $id] | new CustomerCreatedEvent($id) |
| Registry | private array $providers | private ProviderCollection $providers |
Benefits of Typed Classes
- ✅ IDE autocompletion and refactoring support
- ✅ Static analysis catches type errors
- ✅ Self-documenting code
- ✅ Encapsulation (validation in constructor)
- ✅ Single Responsibility
- ✅ Open/Closed principle (extend via new classes)
Collection Pattern
$metrics = [
['name' => 'OrdersPlaced', 'value' => 1],
['name' => 'OrderValue', 'value' => 99.99],
];
$metrics = new MetricCollection(
new OrdersPlacedMetric(value: 1),
new OrderValueMetric(value: 99.99)
);
When Arrays ARE Acceptable
- Simple key-value maps for serialization output (
toArray() methods)
- Framework integration points requiring arrays
- Temporary internal data within a single method
- Internal storage inside collection classes
Cross-Cutting Concerns Pattern
Use event subscribers for cross-cutting concerns (metrics, logging),
NOT direct injection into handlers
Anti-Pattern: Metrics in Command Handler
final class CreateCustomerHandler
{
public function __construct(
private CustomerRepository $repository,
private BusinessMetricsEmitterInterface $metrics // Wrong place!
) {}
public function __invoke(CreateCustomerCommand $cmd): void
{
$customer = Customer::create(...);
$this->repository->save($customer);
$this->metrics->emit(new CustomersCreatedMetric());
}
}
Correct Pattern: Dedicated Event Subscriber
final class CreateCustomerHandler
{
public function __construct(
private CustomerRepository $repository,
private EventBusInterface $eventBus
) {}
public function __invoke(CreateCustomerCommand $cmd): void
{
$customer = Customer::create(...);
$this->repository->save($customer);
$this->eventBus->publish(...$customer->pullDomainEvents());
}
}
final class CustomerCreatedMetricsSubscriber implements DomainEventSubscriberInterface
{
public function __invoke(CustomerCreatedEvent $event): void
{
->metricsEmitter->(->metricFactory->());
}
}
Common Issues and Fixes
Issue 1: Class in Wrong Type Directory
❌ WRONG:
<source_root>/<SharedContext>/Infrastructure/Transformer/UlidValidator.php
✅ CORRECT:
<source_root>/<SharedContext>/Infrastructure/Validator/UlidValidator.php
mv <source_root>/<SharedContext>/Infrastructure/Transformer/UlidValidator.php \
<source_root>/<SharedContext>/Infrastructure/Validator/UlidValidator.php
Issue 2: Vague Variable Names
❌ WRONG:
private UlidTypeConverter $converter;
✅ CORRECT:
private UlidTypeConverter $typeConverter;
Issue 3: Misleading Parameter Names
❌ WRONG:
public function fromBinary(mixed $binary): Ulid // Accepts mixed, not just binary
✅ CORRECT:
public function fromBinary(mixed $value): Ulid // Accurate!
Issue 4: Helper/Util Classes
❌ WRONG:
class CustomerHelper {
public function validateEmail() {}
public function formatName() {}
public function convertData() {}
}
✅ CORRECT: Extract specific responsibilities
- CustomerEmailValidator (Validator/)
- CustomerNameFormatter (Formatter/)
- CustomerDataConverter (Converter/)
Issue 5: Namespace Mismatch
❌ WRONG:
namespace App\Shared\Infrastructure\Transformer;
✅ CORRECT:
namespace App\Shared\Infrastructure\Validator;
Decision Tree: Where Does It Belong?
What does the class DO?
├─ Converts between types (string ↔ object)? → Converter/
├─ Transforms for DB/serialization? → Transformer/
├─ Validates values? → Validator/
├─ Builds/constructs objects? → Builder/
├─ Fixes/modifies data? → Fixer/
├─ Creates complex objects? → Factory/
├─ Resolves/determines values? → Resolver/
├─ Normalizes/serializes? → Serializer/
├─ Formats data for display? → Formatter/
├─ Maps data between structures? → Mapper/
├─ Provides data/cookies/context? → Provider/
└─ Something else? → Ask the user before creating a new directory!
Verification Commands
grep -r "class.*Helper" <architecture.source_root>/
grep -r "class.*Util" <architecture.source_root>/
grep -r 'private.*\$converter;' <architecture.source_root>/
If a make.* entry is null, the capability is absent — note the skip
and fall back to the remaining checks instead of inventing a target.
Service Configuration: No Redundant Wiring
Applies when framework.name is symfony (adapt the mechanics for
other DI containers; the rule itself is generic).
Do not add explicit interface aliases in services.yaml when
autowiring can resolve them automatically.
Rule
When an interface has exactly one implementation under
architecture.source_root, autowiring automatically aliases the
interface to that implementation. Do NOT add a manual alias — it is
redundant.
When an Explicit Alias IS Required
- The interface has multiple implementations (e.g., a cached
decorator plus the persistence implementation)
- The implementation lives outside the autowired source resource
(e.g., a third-party bundle class)
- You need to alias to a different implementation than what
autowiring would pick
When an Explicit Alias is REDUNDANT (remove it)
- Only one class under
architecture.source_root implements the interface
- Both the interface and implementation are covered by the autowired
resource in
services.yaml
Example
App\Customer\Domain\Repository\PaymentTokenRepositoryInterface:
alias: App\Customer\Infrastructure\Repository\RedisPaymentTokenRepository
App\Customer\Domain\Repository\CustomerRepositoryInterface:
alias: App\Customer\Infrastructure\Repository\CachedCustomerRepository
(Customer stands for any entry of architecture.bounded_contexts.)
Explicit Constructor Arguments Are Still Needed
Even when the alias is redundant, you may still need an explicit service
definition for constructor arguments that autowiring cannot resolve
(e.g., non-type-hinted parameters, named service references):
App\Customer\Infrastructure\Repository\RedisStateRepository:
arguments:
$stateRedis: '@customer.redis_connection'
Verification
bin/console debug:container <InterfaceName>
Constraints (Never Do This)
NEVER:
- Place class in wrong type directory (violates "Directory X contains ONLY class type X")
- Allow Domain layer to import framework code (
framework.name components, Doctrine, API Platform)
- Use vague variable names (
$converter, $resolver - be specific!)
- Create "Helper" or "Util" classes (extract specific responsibilities)
- Allow namespace to mismatch directory structure
- Use arrays for structured data when typed classes would be appropriate
- Use untyped
array in method signatures — always specify content type via docblock or use collection classes
- Use
array type for collections of domain/application objects — use typed collections
- Use
json_encode/json_decode — use the framework serializer
- Use constructor defaults that instantiate collaborators — inject the dependency instead
- Use direct
new for value objects with named constructors — use {ValueObject}::fromString()
- Inject cross-cutting concerns (metrics, logging) into command handlers
- Create complex objects directly without factories in production code
- Add redundant interface aliases in service config when autowiring resolves them
- Add suppression annotations (
@psalm-suppress, @phpstan-ignore*, phpcs:ignore) instead of fixing structure
- Lower any
quality.* threshold or edit deptrac.yaml to make misplaced code pass
ALWAYS:
- Verify "Directory X contains ONLY class type X" principle
- Use specific variable names (
$typeConverter, not $converter)
- Use accurate parameter names (match actual types)
- Ensure namespace matches directory structure exactly
- Extract specific responsibilities from Helper/Util classes
- Prefer typed classes over arrays for structured data
- Always specify array content types in method signatures (e.g.
list<string>, array<string, int>)
- Use typed collection classes instead of arrays of objects
- Use the framework serializer instead of
json_encode/json_decode
- Inject dependencies instead of instantiating constructor defaults
- Use named constructors for value objects in production code
- Use event subscribers for cross-cutting concerns
- Use factories for complex object creation in production code
Hardcoded Configuration Values → .env Extraction
Configurable values (TTLs, timeouts, limits, sizes, batch counts)
belong in .env, not as class constants.
When to Extract
Extract a constant to .env when it represents:
- Time durations: TTLs, timeouts, expiration periods, intervals
- Rate limits: Max requests, windows, thresholds
- Sizes: Batch sizes, max body sizes, token lengths
- Retry configuration: Delay, max attempts, backoff intervals
- Infrastructure tunables: Cache TTLs, queue settings, lockout parameters
When NOT to Extract
Keep as constants when the value is:
- Protocol/spec-defined: HTTP status codes, cipher IV lengths, segment lengths
- Security-critical internal: Encryption tag lengths, HSTS header values
- Domain invariants: Validation rules that are part of the domain model
Extraction Pattern (3-Step)
Step 1: Add env variable to .env and .env.test
# .env
CACHE_CUSTOMER_BY_ID_TTL=600
CACHE_CUSTOMER_BY_EMAIL_TTL=300
# .env.test (same or test-appropriate value)
CACHE_CUSTOMER_BY_ID_TTL=600
CACHE_CUSTOMER_BY_EMAIL_TTL=300
Step 2: Bind in the service config (config/services.yaml for Symfony)
App\Customer\Infrastructure\Repository\CachedCustomerRepository:
arguments:
$ttlById: '%env(int:CACHE_CUSTOMER_BY_ID_TTL)%'
$ttlByEmail: '%env(int:CACHE_CUSTOMER_BY_EMAIL_TTL)%'
Step 3: Replace constant with constructor parameter
final class CachedCustomerRepository
{
private const TTL_BY_ID = 600;
private const TTL_BY_EMAIL = 300;
}
final readonly class CachedCustomerRepository
{
public function __construct(
private CustomerRepositoryInterface $inner,
private CacheInterface $cache,
private int $ttlById,
private int $ttlByEmail,
) {
}
}
Common Extraction Candidates
| Pattern in Source | Extract To .env |
|---|
private const TTL_* = <seconds> | CACHE_*_TTL=<seconds> |
private const EXPIRES_AFTER_* = <value> | TOKEN_EXPIRATION_SECONDS=<value> |
private const MAX_ATTEMPTS = <n> | *_MAX_ATTEMPTS=<n> |
private const BATCH_SIZE = <n> | *_BATCH_SIZE=<n> |
private const DEFAULT_*_SECONDS = <n> | *_SECONDS=<n> |
Constructor default = 900 | Remove default, bind via service config |
Verification After Extraction
Run, in order:
- Target mapped by
make.phpinsights — style score stays at
quality.phpinsights.style
- Target mapped by
make.psalm — quality.psalm_errors (= 0) errors
- Target mapped by
make.tests — update mocks for new constructor params
- Target mapped by
make.ci — full validation
CI Integration: When CI Fails
When the target mapped by make.ci fails, consult this skill if the
failure involves:
| CI Failure Indicator | Code Organization Fix |
|---|
| Class not found / namespace mismatch | Verify namespace matches directory structure |
| Deptrac violation after moving class | Check layer placement (Domain/Application/Infra) |
| PHPInsights architecture score drop | Verify "Directory X contains ONLY class type X" |
| Psalm type errors after refactoring | Check that imports and namespaces were all updated |
| Test failures after class move | Move test file too, update test namespace + imports |
Thresholds come from the profile only: PHPInsights scores must stay at
quality.phpinsights.architecture / quality.phpinsights.style (default
100) and quality.phpinsights.complexity (default 94); Deptrac at
quality.deptrac_violations and Psalm at quality.psalm_errors (fixed
ceilings of 0). Score floors are raise-only (ADR-7): a profile may
tighten them, never relax them — fix the code, never the threshold.
Refactoring Checklist (Before Running CI)
When moving, renaming, or restructuring classes:
architecture:
source_root: src
bounded_contexts: [User, OAuth]
shared_context: Shared
framework:
name: symfony
api_platform: "4.2"
graphql: true
persistence:
mapper: doctrine-odm
make:
ci: ci
psalm: psalm
deptrac: deptrac
phpinsights: phpinsights
tests: tests
quality:
phpinsights: {architecture: 100, style: 100, complexity: 94}
deptrac_violations: 0
psalm_errors: 0
Related Skills
Related Documentation
See DIRECTORY-STRUCTURE.md for the complete
layer-by-layer directory reference, file naming conventions, and
step-by-step placement guides.