Comprehensive Bug Fixes, Late Static Binding, Type Alias Expansion & Line-Drift Hardening

.gitignore

@@ -5,4 +5,5 @@
 docs/.vitepress/cache
 docs/.vitepress/dist
 /manual-tests
-composer.lock
+composer.lock
+index.php

docs/advanced/liskov-and-inheritance.md

@@ -205,7 +205,9 @@ $model->setTraitId(-50);
 AppModel::setTraitVersion('');
 // Throws: TypeError: Property AppModel::$traitVersion must be of type non-empty-string
 ```
+
 ---
+
 ## Trait Inheritance Across Parent-Child Classes
 
 When a parent class uses a Trait (`ParentClass` uses `LoggerTrait`), any child class extending the parent (`ChildClass extends ParentClass`) automatically inherits all `@param`, `@return`, and `@var` contracts declared on the parent's Trait:
@@ -242,6 +244,43 @@ $child->logMessage(10, 'boot');
 $child->logMessage(-50, 'boot');
 // Throws: TypeError: ChildService::logMessage(): Argument $level must be of type positive-int
 ```
+
+---
+
+## Trait Method Aliasing (`use Trait { oldMethod as newMethod; }`)
+
+When a class uses a Trait and renames a method using PHP's trait `as` alias syntax, TypePHP inspects trait alias mappings and automatically inherits the original Trait method's DocBlock contracts onto the aliased method:
+
+```php
+trait LoggerTrait
+{
+    /**
+     * @param positive-int $level
+     * @param non-empty-string $message
+     */
+    public function logEvent(int $level, string $message): bool
+    {
+        return true;
+    }
+}
+
+class AuditService
+{
+    use LoggerTrait {
+        logEvent as recordAuditLog; // Aliases method from trait!
+    }
+}
+
+$service = new AuditService();
+
+// Valid Call
+$service->recordAuditLog(1, 'audit_ok');
+
+// Invalid Call ($level = -1 violates inherited Trait's @param positive-int)
+$service->recordAuditLog(-1, 'audit_ok');
+// Throws: TypeError: Argument $level must be of type positive-int
+```
+
 ---
 
 ## Partial Parameter Overriding (Gap-Filling)
@@ -292,42 +331,57 @@ $service->update(10, 'Charlie');
 
 ---
 
-## Parameter Renaming ($id → $userId) & Position Shifts
+## Parameter Renaming ($id → $userId) & Position Shift Disambiguation
 
-When a child class or attribute constructor overrides a parent method, parameter positions or parameter names may shift. TypePHP resolves parameter contract inheritance using **Name-First Resolution**:
+When a child class, constructor, or trait implementation overrides an ancestor method, parameter positions may shift when new parameters are inserted, or parameter names may be renamed.
 
-1. **Name Matching:** If a parameter name in the child method matches a parameter name in the parent class (e.g. `$api`), the parent's contract is inherited by that parameter regardless of its position index in the child.
-2. **Position Fallback:** If a parameter is renamed in the child class (e.g., `$id` $\rightarrow$ `$userId`), TypePHP falls back to matching by position index.
+TypePHP resolves parameter contract inheritance using **3-Tier Name & Position Disambiguation**:
+
+1. **Name-First Matching:** If a parameter name in the child method matches a parameter name in the parent class (e.g. `$container`), the parent's contract is mapped to that parameter regardless of its position index in the child.
+2. **Position Fallback on Renamed Parameters:** If a parameter is renamed in the child class (e.g., `$id` $\rightarrow$ `$userId`), TypePHP maps the contract using its position index.
+3. **Candidate Disambiguation (Shift Protection):** If a child class inserts a new parameter at index 0 (shifting all subsequent parameters down), TypePHP **verifies that the candidate child parameter does not already exist in the parent under its own name**. This prevents parent parameter contracts from accidentally mis-mapping onto shifted child parameters!
 
 ```php
-class BaseField
+class BaseRegistry
 {
     /**
-     * Parent constructor has $api at position #1
+     * Parent constructor has 3 params:
+     * Index 0: $container
+     * Index 1: $definitions
+     * Index 2: $repositoryMap
      *
-     * @param string $type
-     * @param bool|array{admin-api: bool} $api
+     * @param array<string, string> $definitions
+     * @param array<string, string> $repositoryMap
      */
-    public function __construct(string $type, bool|array $api = false) {}
+    public function __construct(
+        ContainerInterface $container,
+        array $definitions,
+        array $repositoryMap
+    ) {}
 }
 
-class OneToManyRelation extends BaseField
+class SalesChannelRegistry extends BaseRegistry
 {
     /**
-     * Child inserts $entity, $ref, $onDelete BEFORE $api (position shift!)
+     * Child inserts $prefix at Index 0 (shifting $container to Index 1),
+     * and renames $definitions -> $definitionMap at Index 2!
+     *
+     * @param array<string, string> $definitionMap
+     * @param array<string, string> $repositoryMap
      */
     public function __construct(
-        string $entity,
-        string $ref,
-        OnDeleteOption $onDelete = OnDeleteOption::NO_ACTION,
-        bool|array $api = false
+        string $prefix,
+        ContainerInterface $container,
+        array $definitionMap,
+        array $repositoryMap
     ) {
-        parent::__construct('one-to-many', $api);
+        parent::__construct($container, $definitionMap, $repositoryMap);
     }
 }
 
-// $onDelete (position #2 in child) is NOT overwritten by $api's type (position #1 in parent)!
-$attr = new OneToManyRelation('unit', 'unit_id', OnDeleteOption::CASCADE, true);
+// TypePHP correctly keeps $container (Index 1 in child) untouched,
+// rather than mis-mapping parent's @param array $definitions (Index 1 in parent) onto it!
+new SalesChannelRegistry('sales_channel.', new Container(), ['prod' => 'ProductDef'], ['prod' => 'ProductRepo']);
 ```
 
 ---

docs/core-concepts/function-contracts.md

@@ -36,6 +36,7 @@ registerUser(-5, 'Alice', 'admin');
 > **Execution Order Note:** Native PHP type hints (e.g., `int $id`, `string $username`) are evaluated by PHP's C-engine *before* function execution begins. TypePHP's extended PHPDoc contracts (e.g., `positive-int`, `non-empty-string`) execute at the very start of the function/method body. If a native type hint fails, PHP throws its native `TypeError` before TypePHP's guard rails run.
 
 ---
+
 ## PHP 8.0+ Named Arguments
 
 TypePHP natively supports PHP 8.0+ Named Arguments. Because parameter contracts are mapped by parameter name rather than argument position index, you can pass named arguments in any order, and TypePHP will accurately validate each parameter:
@@ -62,6 +63,7 @@ registerUser(age: 25, username: 'Alice', id: 42);
 registerUser(age: 25, username: 'Alice', id: -5);
 // Throws: TypeError: registerUser(): Argument $id must be of type positive-int, negative int (-5) given
 ```
+
 ---
 
 ## Class Methods (Instance & Static)
@@ -189,29 +191,6 @@ getUserStatus(-10);
 
 ---
 
-## Variadic Parameter Contracts
-
-When a function or method accepts variadic arguments (`...$items`), TypePHP validates every element passed in the variadic argument list:
-
-```php
-/**
- * @param positive-int ...$ids
- */
-function deleteUsers(int ...$ids): void
-{
-    // ...
-}
-
-// Valid Call
-deleteUsers(10, 20, 30);
-
-// Invalid Call (3rd variadic item violates positive-int)
-deleteUsers(10, 20, -5);
-// Throws: TypeError: deleteUsers(): Argument $ids[2] must be of type positive-int
-```
-
----
-
 ## Fluent `$this` Identity Returns
 
 For fluent builder or service classes annotated with `@return $this`, TypePHP verifies strict object identity (`$result === $this`), preventing accidental instantiation of new instances:
@@ -247,6 +226,96 @@ $builder->cloneSelf();
 
 ---
 
+## Late Static Binding Return Contracts (`@return static`)
+
+When a parent class method (static factory method or fluent instance method) is annotated with `@return static`, TypePHP enforces **Late Static Binding** at runtime. 
+
+It dynamically verifies that the returned object is an instance of the **actual calling class** (`UserEntityFactory`), strictly rejecting parent instances (`BaseEntityFactory`), sibling instances (`AdminEntityFactory`), or generic objects (`stdClass`):
+
+```php
+abstract class BaseEntityFactory
+{
+    /**
+     * @return static
+     */
+    public static function create(): static
+    {
+        return new static();
+    }
+
+    /**
+     * @return static
+     */
+    public static function createSibling(): object
+    {
+        return new AdminEntityFactory(); // Invalid: Returns sibling instead of calling class!
+    }
+}
+
+class UserEntityFactory extends BaseEntityFactory {}
+class AdminEntityFactory extends BaseEntityFactory {}
+
+// Valid: Returns UserEntityFactory instance matching the late-static calling class
+$user = UserEntityFactory::create();
+
+// Invalid: UserEntityFactory called, but AdminEntityFactory was returned!
+UserEntityFactory::createSibling();
+// Throws: TypeError: UserEntityFactory::createSibling(): Return value must be of type App\UserEntityFactory, App\AdminEntityFactory returned
+```
+
+### Late Static Binding with Generics (`static<T>`)
+
+Late static binding seamlessly integrates with TypePHP's Reified Generics engine. A static factory can return a specialized generic instance of the late-static-bound calling class:
+
+```php
+/**
+ * @template T
+ */
+abstract class BaseGenericFactory
+{
+    /**
+     * @template TValue
+     * @param TValue $value
+     * @return static<TValue>
+     */
+    public static function of(mixed $value): static
+    {
+        return new static($value);
+    }
+}
+
+class UserGenericFactory extends BaseGenericFactory {}
+
+// 1. Returns UserGenericFactory instance
+// 2. Binds generic template T = Dog in WeakMap memory!
+$factory = UserGenericFactory::of(new Dog());
+```
+
+---
+
+## Variadic Parameter Contracts
+
+When a function or method accepts variadic arguments (`...$items`), TypePHP validates every element passed in the variadic argument list:
+
+```php
+/**
+ * @param positive-int ...$ids
+ */
+function deleteUsers(int ...$ids): void
+{
+    // ...
+}
+
+// Valid Call
+deleteUsers(10, 20, 30);
+
+// Invalid Call (3rd variadic item violates positive-int)
+deleteUsers(10, 20, -5);
+// Throws: TypeError: deleteUsers(): Argument $ids[2] must be of type positive-int
+```
+
+---
+
 ## Conditional Return Types
 
 TypePHP supports parameter-based conditional return types (`@return ($param is true ? TypeA : TypeB)`):
@@ -270,13 +339,14 @@ formatValue(false, 'hello'); // Evaluates return type as non-empty-string
 formatValue(true, 'not_an_int');
 // Throws: TypeError: formatValue(): Return value must be of type positive-int
 ```
+
 ---
 
 ## PHP 8.0+ Attributes Coexistence
 
 TypePHP seamlessly coexists with native PHP 8.0+ Attributes (`#[Route]`, `#[Inject]`, `#[Validate]`). 
 
-You can place your PHPDoc annotations **either above or below** native PHP attributes on properties, methods/functions. TypePHP's AST engine and PHP's Reflection API process both metadata channels independently without any syntax conflicts:
+You can place your PHPDoc annotations **either above or below** native PHP attributes on properties, methods, or functions. TypePHP's AST engine and PHP's Reflection API process both metadata channels independently without any syntax conflicts:
 
 ```php
 // Option A: DocBlock ABOVE Attribute (Supported)

src/Internal/Checker/GeneratorChecker.php

@@ -29,7 +29,7 @@ public static function checkSend(string $function, mixed $sendValue, TypeValidat
             if ($sendTypeNode !== null) {
                 $err = $registry->validate($sendValue, $sendTypeNode, "$function(): Generator sent value (TSend)");
                 if ($err !== null) {
-                    throw new \TypePHP\Exception\TypeError($err->getMessage());
+                    return $err;
                 }
             }
         }
@@ -64,14 +64,14 @@ public static function checkYield(string $function, mixed $key, mixed $value, Ty
         if ($key !== null && $keyTypeNode !== null) {
             $err = $registry->validate($key, $keyTypeNode, "$function(): Return iterator key");
             if ($err !== null) {
-                throw new \TypePHP\Exception\TypeError($err->getMessage());
+                return $err;
             }
         }
 
         if ($itemTypeNode !== null) {
             $err = $registry->validate($value, $itemTypeNode, "$function(): Return iterator value");
             if ($err !== null) {
-                throw new \TypePHP\Exception\TypeError($err->getMessage());
+                return $err;
             }
         }
 

src/Internal/Checker/ParamChecker.php

@@ -17,6 +17,7 @@
 use TypePHP\Internal\TypeFormatter;
 use TypePHP\Resolver\SpecialTypeResolver;
 use TypePHP\Resolver\TemplateManager;
+use TypePHP\Resolver\TemplateSubstitutor;
 use TypePHP\Validator\TypeValidatorRegistry;
 
 /**
@@ -27,17 +28,19 @@ final class ParamChecker
     /**
      * @param array<string, mixed> $vars
      */
-    public static function checkParams(string $function, array $vars, ?object $thisObj, TypeValidatorRegistry $registry): ?ErrorMessage
+    public static function checkParams(string $function, array $vars, object|string|null $thisOrClass, TypeValidatorRegistry $registry): ?ErrorMessage
     {
         if (! (bool) (Config::get()['params'] ?? true)) {
             return null;
         }
 
+        $thisObj = \is_object($thisOrClass) ? $thisOrClass : null;
         $effectiveFunction = $function;
-        if ($thisObj !== null && str_contains($function, '::')) {
+
+        if (str_contains($function, '::')) {
             [$classOrTrait, $methodName] = explode('::', $function, 2);
-            $actualClassName = \get_class($thisObj);
-            if ($actualClassName !== $classOrTrait) {
+            $actualClassName = \is_object($thisOrClass) ? \get_class($thisOrClass) : (\is_string($thisOrClass) ? $thisOrClass : null);
+            if ($actualClassName !== null && $actualClassName !== $classOrTrait) {
                 $effectiveFunction = $actualClassName . '::' . $methodName;
             }
         }
@@ -76,6 +79,9 @@ public static function checkParams(string $function, array $vars, ?object $thisO
             TemplateManager::resolveInheritedTemplates($thisObj, $declaringClass);
         }
 
+        $boundTemplates = TemplateManager::getBoundTemplates($effectiveFunction, $thisObj, $templates);
+        $declaredTemplates = $templates;
+
         foreach ($contract['types'] as $paramName => $typeNode) {
             if (! \array_key_exists($paramName, $vars)) {
                 continue;
@@ -92,6 +98,18 @@ public static function checkParams(string $function, array $vars, ?object $thisO
                 $typeNode = $aliases[$typeNode->name];
             }
 
+            $isClassStringT = ($typeNode instanceof GenericTypeNode && self::isClassStringTemplate($typeNode, $templates));
+
+            $isBareTemplate = ($typeNode instanceof IdentifierTypeNode && isset($templates[$typeNode->name]))
+                || ($typeNode instanceof ArrayTypeNode && $typeNode->type instanceof IdentifierTypeNode && isset($templates[$typeNode->type->name]));
+
+            $shouldSkipTemplateSub = $isBareTemplate || $isClassStringT;
+
+            if (! $shouldSkipTemplateSub && (\count($boundTemplates) > 0 || \count($declaredTemplates) > 0)) {
+                $typeNode = TemplateSubstitutor::substitute($typeNode, $boundTemplates, $declaredTemplates);
+                $typeNode = SpecialTypeResolver::resolve($typeNode, $effectiveFunction, $thisObj);
+            }
+
             if ($typeNode instanceof GenericTypeNode && self::isClassStringTemplate($typeNode, $templates)) {
                 $err = self::resolveClassStringTemplate($typeNode, $val, $paramName, $effectiveFunction, $thisObj, $templates);
                 if ($err !== null) {