codeprobe-solid

Standalone Mode

If invoked directly (not via the orchestrator), you must first:

1. Read ../codeprobe/shared-preamble.md (resolve relative to this SKILL.md's location — the sibling codeprobe skill directory — not the user's project) for the output contract, execution modes, and constraints.
2. Load applicable reference files from ../codeprobe/references/ (same resolution) based on the project's tech stack.
3. Default to full mode unless the user specifies otherwise.

SOLID Principles Auditor

Domain Scope

This sub-skill detects violations of the five SOLID principles:

1. Single Responsibility Principle (SRP) — A class or module should have only one reason to change.
2. Open/Closed Principle (OCP) — Software entities should be open for extension but closed for modification.
3. Liskov Substitution Principle (LSP) — Subtypes must be substitutable for their base types without altering program correctness.
4. Interface Segregation Principle (ISP) — Clients should not be forced to depend on interfaces they do not use.
5. Dependency Inversion Principle (DIP) — High-level modules should not depend on low-level modules; both should depend on abstractions.

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What It Does NOT Flag

• Simple DTOs/value objects with multiple fields — having many properties is not an SRP violation when the class represents a single data concept.
• Small scripts and CLIs that don't need dependency injection — proportional design matters.
• Enums used in switches where the enum is stable and closed (e.g., compass directions, days of the week) — OCP applies when variants are likely to grow.
• Framework-generated classes following framework conventions (e.g., Laravel migrations, Django admin classes, Rails ActiveRecord models with standard callbacks).
• Test helper classes that aggregate setup utilities — test infrastructure has different design constraints.

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Detection Instructions

SRP — Single Responsibility Principle

ID Prefix	Signal	How to Detect	Severity
SRP	Class has 5+ public methods doing unrelated things	Count public methods. If 5+ exist, check whether they cluster around a single responsibility or span multiple concerns (e.g., authentication + email + database). Look for method name prefixes that suggest different domains.	Major
SRP	Method exceeds 30 LOC doing multiple concerns	Count lines in each method (excluding blank lines and comments). If > 30 LOC, check whether the method handles multiple distinct steps (validation, transformation, persistence, notification) that could be extracted.	Minor
SRP	Class name is vague	Flag classes named Manager, Handler, Utils, Helper, Processor, Service (when not domain-qualified) — these names suggest the class has no clear single purpose. Exception: if the class is small (< 5 methods, < 100 LOC), downgrade to suggestion.	Minor
SRP	Constructor takes 5+ dependencies	Count constructor parameters or injected dependencies. 5+ dependencies suggest the class has too many responsibilities. Check whether dependencies serve different domains.	Major

OCP — Open/Closed Principle

ID Prefix	Signal	How to Detect	Severity
OCP	Switch/if-else chains on type or status	Look for switch/if-else chains that branch on a type, status, role, or kind field — especially where adding a new variant requires modifying this block. Count the number of cases: 3+ cases on a growable type is a signal.	Major
OCP	No extension point where variants are likely to grow	When a switch/if-else on type is found, check whether there is an interface, abstract class, strategy pattern, or plugin mechanism that would allow adding new variants without modifying the existing code. If absent, flag it.	Minor

LSP — Liskov Substitution Principle

ID Prefix	Signal	How to Detect	Severity
LSP	Subclass overrides method but changes semantics	Check overridden methods: does the subclass return a fundamentally different type, change the meaning of the return value, or produce side effects the parent does not? Compare method signatures and doc comments.	Major
LSP	Subclass throws exception parent doesn't declare	Look for overridden methods that throw exceptions not present in the parent's throws clause or documented contract. In dynamic languages, look for raise/throw in overrides where the parent method doesn't throw.	Major
LSP	Subclass ignores or no-ops parent behavior	Look for overridden methods with empty bodies, pass, return null, return, or // not implemented comments. The subclass is refusing the parent's contract.	Minor
LSP	instanceof/type checks after polymorphic call	Search for instanceof, is_a, typeof, type(), is checks on objects that should be used polymorphically. If code calls a method on a base type and then checks the concrete type, it signals broken substitutability.	Major

ISP — Interface Segregation Principle

ID Prefix	Signal	How to Detect	Severity
ISP	Interface has 8+ methods	Count methods declared in each interface/abstract class/protocol. If 8+, the interface is likely too broad. Check whether the methods cluster into distinct groups.	Minor
ISP	Class implements interface but leaves methods empty or throwing	Look for interface implementations where one or more methods are empty, return null, throw NotImplementedError/UnsupportedOperationException, or contain only pass/TODO comments.	Major
ISP	Multiple unrelated method groups in one interface	Analyze the interface's methods: do they fall into 2+ distinct responsibility groups (e.g., read operations + write operations + notification methods)? If so, the interface should be split.	Major

DIP — Dependency Inversion Principle

ID Prefix	Signal	How to Detect	Severity
DIP	new ConcreteClass() inside business logic	Search for direct instantiation (new ClassName(), direct constructor calls) of infrastructure or service classes inside business logic methods. Exclude: DTOs, value objects, exceptions, collections, factories, and DI container registrations.	Major
DIP	High-level module imports from infrastructure layer directly	Check import statements: does a domain/business logic module import directly from database drivers, HTTP clients, file system libraries, or third-party SDKs without an abstraction layer? Look for patterns like import mysql, use Illuminate\Support\Facades\DB, from requests import.	Major
DIP	No constructor injection — static method calls to concrete dependencies	Look for static method calls like Database::query(), Cache::get(), Logger.log() in business logic where no interface is injected. The class is tightly coupled to the concrete implementation via static access.	Minor

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ID Prefixes & Fix Prompt Examples

• SRP- — Single Responsibility Principle violations
• OCP- — Open/Closed Principle violations
• LSP- — Liskov Substitution Principle violations
• ISP- — Interface Segregation Principle violations
• DIP- — Dependency Inversion Principle violations

Number findings sequentially within each prefix: SRP-001, SRP-002, OCP-001, etc.

Fix Prompt Examples

• "Refactor src/OrderService.php: extract payment logic (lines 45-78) into a new PaymentService class. Inject PaymentService via constructor into OrderService. Move methods calculateTotal(), applyDiscount(), and processPayment() to the new class."
• "Replace the switch on $type in NotificationSender (lines 30-65) with a Strategy pattern: create a NotificationChannel interface with a send(Message $message) method. Create EmailChannel, SmsChannel, and PushChannel implementations. Use a NotificationChannelFactory to resolve the correct channel by type."
• "In UserRepository.php, replace new MySqlConnection() at line 23 with constructor injection: add a DatabaseConnectionInterface $connection parameter to the constructor and use it instead of the concrete instantiation."