diff --git a/lib/private/AppFramework/Http/Dispatcher.php b/lib/private/AppFramework/Http/Dispatcher.php
index 2fa6bd8f1cb..a6b44d9fb96 100644
--- a/lib/private/AppFramework/Http/Dispatcher.php
+++ b/lib/private/AppFramework/Http/Dispatcher.php
@@ -16,6 +16,7 @@ use OC\DB\ConnectionAdapter;
 use OCP\App\IAppManager;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http\DataResponse;
+use OCP\AppFramework\Http\InvalidStringParameterException;
 use OCP\AppFramework\Http\ParameterOutOfRangeException;
 use OCP\AppFramework\Http\Response;
 use OCP\Diagnostics\IEventLogger;
@@ -160,6 +161,8 @@ class Dispatcher {
 			} elseif ($value !== null && \in_array($type, $types, true)) {
 				settype($value, $type);
 				$this->ensureParameterValueSatisfiesRange($param, $value, $default);
+			} elseif ($value !== null && $type === 'string' && \is_string($value)) {
+				$this->ensureParameterValueSatisfiesStringConstraint($param, $value);
 			} elseif ($value === null && $type !== null && $this->appContainer->has($type)) {
 				$value = $this->appContainer->get($type);
 			}
@@ -225,4 +228,13 @@ class Dispatcher {
 			}
 		}
 	}
+
+	/**
+	 * @throws InvalidStringParameterException
+	 */
+	private function ensureParameterValueSatisfiesStringConstraint(string $param, string $value): void {
+		if (!$this->reflector->satisfiesStringConstraint($param, $value)) {
+			throw new InvalidStringParameterException($param, $this->reflector->getStringConstraint($param));
+		}
+	}
 }
diff --git a/lib/private/AppFramework/Utility/ControllerMethodReflector.php b/lib/private/AppFramework/Utility/ControllerMethodReflector.php
index e09756a957b..3c2a7d01f61 100644
--- a/lib/private/AppFramework/Utility/ControllerMethodReflector.php
+++ b/lib/private/AppFramework/Utility/ControllerMethodReflector.php
@@ -20,6 +20,7 @@ class ControllerMethodReflector implements IControllerMethodReflector {
 	private array $types = [];
 	private array $parameters = [];
 	private array $ranges = [];
+	private array $stringConstraints = [];
 	private int $startLine = 0;
 	private string $file = '';
 	private ?\ReflectionMethod $reflectionMethod = null;
@@ -38,6 +39,7 @@ class ControllerMethodReflector implements IControllerMethodReflector {
 		$this->types = [];
 		$this->parameters = [];
 		$this->ranges = [];
+		$this->stringConstraints = [];
 		$this->reflectionMethod = new \ReflectionMethod($object, $method);
 		$this->startLine = $this->reflectionMethod->getStartLine();
 		$this->file = $this->reflectionMethod->getFileName();
@@ -79,6 +81,23 @@ class ControllerMethodReflector implements IControllerMethodReflector {
 					'max' => $matches['rangeMax'][$index] === 'max' ? PHP_INT_MAX : (int)$matches['rangeMax'][$index],
 				];
 			}
+
+			// extract psalm int aliases that imply a fixed range
+			preg_match_all('/@(?:psalm-)?param\h+(\?)?(?P<type>positive-int|non-negative-int|negative-int|non-positive-int)(\|null)?\h+\$(?P<var>\w+)/', $docs, $matches);
+			foreach ($matches['var'] as $index => $varName) {
+				$this->ranges[$varName] = match ($matches['type'][$index]) {
+					'positive-int' => ['min' => 1, 'max' => PHP_INT_MAX],
+					'non-negative-int' => ['min' => 0, 'max' => PHP_INT_MAX],
+					'negative-int' => ['min' => PHP_INT_MIN, 'max' => -1],
+					'non-positive-int' => ['min' => PHP_INT_MIN, 'max' => 0],
+				};
+			}
+
+			// extract psalm scalar string types
+			preg_match_all('/@(?:psalm-)?param\h+(\?)?(?P<type>non-empty-lowercase-string|non-falsy-string|non-empty-string|lowercase-string|numeric-string)(\|null)?\h+\$(?P<var>\w+)/', $docs, $matches);
+			foreach ($matches['var'] as $index => $varName) {
+				$this->stringConstraints[$varName] = $matches['type'][$index];
+			}
 		}
 
 		foreach ($this->reflectionMethod->getParameters() as $param) {
@@ -120,6 +139,25 @@ class ControllerMethodReflector implements IControllerMethodReflector {
 		return null;
 	}
 
+	public function getStringConstraint(string $parameter): ?string {
+		return $this->stringConstraints[$parameter] ?? null;
+	}
+
+	/**
+	 * Whether $value satisfies the psalm string type annotated for $parameter,
+	 * or true if none was annotated
+	 */
+	public function satisfiesStringConstraint(string $parameter, string $value): bool {
+		return match ($this->getStringConstraint($parameter)) {
+			'non-empty-string' => $value !== '',
+			'non-empty-lowercase-string' => $value !== '' && $value === strtolower($value),
+			'lowercase-string' => $value === strtolower($value),
+			'non-falsy-string' => $value !== '' && $value !== '0',
+			'numeric-string' => is_numeric($value),
+			default => true,
+		};
+	}
+
 	/**
 	 * @return array the arguments of the method with key => default value
 	 */
diff --git a/lib/public/AppFramework/Http/InvalidStringParameterException.php b/lib/public/AppFramework/Http/InvalidStringParameterException.php
new file mode 100644
index 00000000000..16d92eec469
--- /dev/null
+++ b/lib/public/AppFramework/Http/InvalidStringParameterException.php
@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+namespace OCP\AppFramework\Http;
+
+/**
+ * @since 35.0.0
+ */
+class InvalidStringParameterException extends \InvalidArgumentException {
+	/**
+	 * @since 35.0.0
+	 */
+	public function __construct(
+		protected string $parameterName,
+		protected string $constraint,
+	) {
+		parent::__construct(
+			sprintf('Parameter %s must be a %s', $this->parameterName, $this->constraint)
+		);
+	}
+
+	/**
+	 * @since 35.0.0
+	 */
+	public function getParameterName(): string {
+		return $this->parameterName;
+	}
+
+	/**
+	 * @since 35.0.0
+	 */
+	public function getConstraint(): string {
+		return $this->constraint;
+	}
+}
diff --git a/tests/lib/AppFramework/Http/DispatcherTest.php b/tests/lib/AppFramework/Http/DispatcherTest.php
index 3e90108c60e..af261131543 100644
--- a/tests/lib/AppFramework/Http/DispatcherTest.php
+++ b/tests/lib/AppFramework/Http/DispatcherTest.php
@@ -16,6 +16,7 @@ use OC\AppFramework\Utility\ControllerMethodReflector;
 use OCP\AppFramework\Controller;
 use OCP\AppFramework\Http;
 use OCP\AppFramework\Http\DataResponse;
+use OCP\AppFramework\Http\InvalidStringParameterException;
 use OCP\AppFramework\Http\JSONResponse;
 use OCP\AppFramework\Http\ParameterOutOfRangeException;
 use OCP\AppFramework\Http\Response;
@@ -586,4 +587,45 @@ class DispatcherTest extends \Test\TestCase {
 			$this->assertTrue(true);
 		}
 	}
+
+	public static function stringConstraintDataProvider(): array {
+		return [
+			[true, null, false],
+			[true, 'non-empty-string', false],
+			[false, 'non-empty-string', true],
+		];
+	}
+
+	#[\PHPUnit\Framework\Attributes\DataProvider('stringConstraintDataProvider')]
+	public function testEnsureParameterValueSatisfiesStringConstraint(bool $satisfies, ?string $constraint, bool $throw): void {
+		$this->reflector = $this->createMock(ControllerMethodReflector::class);
+		$this->reflector->expects($this->any())
+			->method('satisfiesStringConstraint')
+			->willReturn($satisfies);
+		$this->reflector->expects($this->any())
+			->method('getStringConstraint')
+			->willReturn($constraint);
+
+		$this->dispatcher = new Dispatcher(
+			$this->http,
+			$this->middlewareDispatcher,
+			$this->reflector,
+			$this->request,
+			$this->config,
+			Server::get(IDBConnection::class),
+			$this->logger,
+			$this->eventLogger,
+			$this->container,
+		);
+
+		if ($throw) {
+			$this->expectException(InvalidStringParameterException::class);
+		}
+
+		self::invokePrivate($this->dispatcher, 'ensureParameterValueSatisfiesStringConstraint', ['myArgument', '']);
+		if (!$throw) {
+			// do not mark this test risky
+			$this->assertTrue(true);
+		}
+	}
 }
diff --git a/tests/lib/AppFramework/Utility/ControllerMethodReflectorTest.php b/tests/lib/AppFramework/Utility/ControllerMethodReflectorTest.php
index 1fd89039807..618f3feef9c 100644
--- a/tests/lib/AppFramework/Utility/ControllerMethodReflectorTest.php
+++ b/tests/lib/AppFramework/Utility/ControllerMethodReflectorTest.php
@@ -63,6 +63,41 @@ class MiddleController extends BaseController {
 	 */
 	public function test5(int $rangedOne, int $rangedTwo, ?int $rangedThree, ?int $rangedFour) {
 	}
+
+	/**
+	 * @psalm-param positive-int $positive
+	 * @psalm-param non-negative-int $nonNegative
+	 * @psalm-param negative-int $negative
+	 * @psalm-param non-positive-int $nonPositive
+	 * @psalm-param positive-int|null $positiveOrNull
+	 * @psalm-param ?non-negative-int $nonNegativeOrNull
+	 * @return void
+	 */
+	public function test6(int $positive, int $nonNegative, int $negative, int $nonPositive, ?int $positiveOrNull, ?int $nonNegativeOrNull) {
+	}
+
+	/**
+	 * @psalm-param non-empty-string $nonEmpty
+	 * @psalm-param non-empty-lowercase-string $nonEmptyLowercase
+	 * @psalm-param lowercase-string $lowercase
+	 * @psalm-param non-falsy-string $nonFalsy
+	 * @psalm-param numeric-string $numeric
+	 * @psalm-param non-empty-string|null $nonEmptyOrNull
+	 * @psalm-param ?non-empty-string $nonEmptyOrNullPrefix
+	 * @psalm-param string $plain
+	 * @return void
+	 */
+	public function test7(
+		string $nonEmpty,
+		string $nonEmptyLowercase,
+		string $lowercase,
+		string $nonFalsy,
+		string $numeric,
+		?string $nonEmptyOrNull,
+		?string $nonEmptyOrNullPrefix,
+		string $plain,
+	) {
+	}
 }
 
 class EndController extends MiddleController {
@@ -275,4 +310,86 @@ class ControllerMethodReflectorTest extends \Test\TestCase {
 		$this->assertSame(-70, $rangeInfo3['min']);
 		$this->assertSame(-30, $rangeInfo3['max']);
 	}
+
+	public function testRangeDetectionIntAliases(): void {
+		$reader = new ControllerMethodReflector(Server::get(LoggerInterface::class));
+		$reader->reflect('Test\AppFramework\Utility\EndController', 'test6');
+
+		$positive = $reader->getRange('positive');
+		$this->assertSame(1, $positive['min']);
+		$this->assertSame(PHP_INT_MAX, $positive['max']);
+
+		$nonNegative = $reader->getRange('nonNegative');
+		$this->assertSame(0, $nonNegative['min']);
+		$this->assertSame(PHP_INT_MAX, $nonNegative['max']);
+
+		$negative = $reader->getRange('negative');
+		$this->assertSame(PHP_INT_MIN, $negative['min']);
+		$this->assertSame(-1, $negative['max']);
+
+		$nonPositive = $reader->getRange('nonPositive');
+		$this->assertSame(PHP_INT_MIN, $nonPositive['min']);
+		$this->assertSame(0, $nonPositive['max']);
+
+		$positiveOrNull = $reader->getRange('positiveOrNull');
+		$this->assertSame(1, $positiveOrNull['min']);
+		$this->assertSame(PHP_INT_MAX, $positiveOrNull['max']);
+
+		$nonNegativeOrNull = $reader->getRange('nonNegativeOrNull');
+		$this->assertSame(0, $nonNegativeOrNull['min']);
+		$this->assertSame(PHP_INT_MAX, $nonNegativeOrNull['max']);
+	}
+
+	public function testStringConstraintDetection(): void {
+		$reader = new ControllerMethodReflector(Server::get(LoggerInterface::class));
+		$reader->reflect('Test\AppFramework\Utility\EndController', 'test7');
+
+		$this->assertSame('non-empty-string', $reader->getStringConstraint('nonEmpty'));
+		$this->assertSame('non-empty-lowercase-string', $reader->getStringConstraint('nonEmptyLowercase'));
+		$this->assertSame('lowercase-string', $reader->getStringConstraint('lowercase'));
+		$this->assertSame('non-falsy-string', $reader->getStringConstraint('nonFalsy'));
+		$this->assertSame('numeric-string', $reader->getStringConstraint('numeric'));
+		$this->assertSame('non-empty-string', $reader->getStringConstraint('nonEmptyOrNull'));
+		$this->assertSame('non-empty-string', $reader->getStringConstraint('nonEmptyOrNullPrefix'));
+		$this->assertNull($reader->getStringConstraint('plain'));
+	}
+
+	public static function stringConstraintDataProvider(): array {
+		return [
+			['non-empty-string', '', false],
+			['non-empty-string', 'a', true],
+			['non-empty-lowercase-string', '', false],
+			['non-empty-lowercase-string', 'ABC', false],
+			['non-empty-lowercase-string', 'abc', true],
+			['lowercase-string', '', true],
+			['lowercase-string', 'ABC', false],
+			['lowercase-string', 'abc', true],
+			['non-falsy-string', '', false],
+			['non-falsy-string', '0', false],
+			['non-falsy-string', '0.0', true],
+			['non-falsy-string', 'a', true],
+			['numeric-string', 'abc', false],
+			['numeric-string', '42', true],
+			['numeric-string', '4.2', true],
+			[null, '', true],
+			[null, 'anything', true],
+		];
+	}
+
+	#[\PHPUnit\Framework\Attributes\DataProvider('stringConstraintDataProvider')]
+	public function testSatisfiesStringConstraint(?string $constraint, string $value, bool $expected): void {
+		$reader = new ControllerMethodReflector(Server::get(LoggerInterface::class));
+		$reader->reflect('Test\AppFramework\Utility\EndController', 'test7');
+
+		$parameter = match ($constraint) {
+			'non-empty-string' => 'nonEmpty',
+			'non-empty-lowercase-string' => 'nonEmptyLowercase',
+			'lowercase-string' => 'lowercase',
+			'non-falsy-string' => 'nonFalsy',
+			'numeric-string' => 'numeric',
+			default => 'plain',
+		};
+
+		$this->assertSame($expected, $reader->satisfiesStringConstraint($parameter, $value));
+	}
 }