diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 189105d..2f3eecb 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -12,5 +12,3 @@ jobs:
     uses: innmind/github-workflows/.github/workflows/psalm-matrix.yml@main
   cs:
     uses: innmind/github-workflows/.github/workflows/cs.yml@main
-    with:
-      php-version: '8.2'
diff --git a/.github/workflows/extensive.yml b/.github/workflows/extensive.yml
new file mode 100644
index 0000000..257f139
--- /dev/null
+++ b/.github/workflows/extensive.yml
@@ -0,0 +1,12 @@
+name: Extensive CI
+
+on:
+  push:
+    tags:
+      - '*'
+    paths:
+      - '.github/workflows/extensive.yml'
+
+jobs:
+  blackbox:
+    uses: innmind/github-workflows/.github/workflows/extensive.yml@main
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6522d61..8aba27e 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,14 @@
 # Changelog
 
+## [Unreleased]
+
+### Changed
+
+- Requires PHP `8.4`
+- Commands name only support alphanumerical characters (use unicode at your own risk)
+- `Innmind\CLI\Environment` is now a final class, all previous implementations are now flagged as internal
+- Requires `innmind/operating-system:~7.0`
+
 ## 4.0.0 - 2025-07-13
 
 ### Added
diff --git a/blackbox.php b/blackbox.php
index 5c3ddce..486f49b 100644
--- a/blackbox.php
+++ b/blackbox.php
@@ -10,6 +10,10 @@
 };
 
 Application::new($argv)
+    ->when(
+        \getenv('BLACKBOX_SET_SIZE') !== false,
+        static fn(Application $app) => $app->scenariiPerProof((int) \getenv('BLACKBOX_SET_SIZE')),
+    )
     ->disableMemoryLimit()
     ->when(
         \getenv('ENABLE_COVERAGE') !== false,
diff --git a/composer.json b/composer.json
index db664a8..07ca13b 100644
--- a/composer.json
+++ b/composer.json
@@ -15,13 +15,13 @@
         "issues": "http://github.com/Innmind/CLI/issues"
     },
     "require": {
-        "php": "~8.2",
-        "innmind/io": "~3.2",
-        "innmind/immutable": "~5.16",
-        "innmind/url": "~4.0",
-        "innmind/operating-system": "~6.0",
-        "innmind/stack-trace": "~4.0",
-        "innmind/validation": "~2.0"
+        "php": "~8.4",
+        "innmind/io": "~4.0",
+        "innmind/immutable": "~6.0",
+        "innmind/url": "~5.0",
+        "innmind/operating-system": "~7.0",
+        "innmind/stack-trace": "~5.0",
+        "innmind/validation": "~3.0"
     },
     "autoload": {
         "psr-4": {
@@ -34,7 +34,7 @@
         }
     },
     "require-dev": {
-        "innmind/static-analysis": "^1.2.1",
+        "innmind/static-analysis": "~1.3",
         "innmind/black-box": "^6.4.1",
         "innmind/coding-standard": "~2.0"
     }
diff --git a/fixtures/thrower.php b/fixtures/thrower.php
index 99ff478..be3515b 100755
--- a/fixtures/thrower.php
+++ b/fixtures/thrower.php
@@ -7,7 +7,6 @@
 use Innmind\CLI\{
     Main,
     Environment,
-    Exception\LogicException,
 };
 use Innmind\OperatingSystem\OperatingSystem;
 use Innmind\Immutable\Attempt;
@@ -15,6 +14,6 @@
 new class extends Main {
     protected function main(Environment $env, OperatingSystem $os): Attempt
     {
-        throw new LogicException('waaat');
+        throw new \LogicException('waaat');
     }
 };
diff --git a/src/Command/Usage.php b/src/Command/Usage.php
index fb61bb7..84b7483 100644
--- a/src/Command/Usage.php
+++ b/src/Command/Usage.php
@@ -358,7 +358,7 @@ public function toString(): string
             ->arguments
             ->map(static fn($argument) => ' '.$argument->toString())
             ->map(Str::of(...))
-            ->fold(new Concat)
+            ->fold(Concat::monoid)
             ->toString();
 
         if ($this->pack->unwrap()) {
@@ -369,7 +369,7 @@ public function toString(): string
             ->options
             ->map(static fn($argument) => ' '.$argument->toString())
             ->map(Str::of(...))
-            ->fold(new Concat)
+            ->fold(Concat::monoid)
             ->toString();
         $string .= ' --help --no-interaction';
 
diff --git a/src/Environment.php b/src/Environment.php
index b840b9f..2089f29 100644
--- a/src/Environment.php
+++ b/src/Environment.php
@@ -3,7 +3,13 @@
 
 namespace Innmind\CLI;
 
-use Innmind\CLI\Environment\ExitCode;
+use Innmind\CLI\Environment\{
+    ExitCode,
+    Implementation,
+    GlobalEnvironment,
+    InMemory,
+};
+use Innmind\IO\IO;
 use Innmind\Url\Path;
 use Innmind\Immutable\{
     Map,
@@ -16,48 +22,130 @@
 /**
  * @psalm-immutable
  */
-interface Environment
+final class Environment
 {
+    private function __construct(
+        private Implementation $implementation,
+    ) {
+    }
+
+    /**
+     * @internal
+     */
+    public static function global(IO $io): self
+    {
+        return new self(GlobalEnvironment::of($io));
+    }
+
+    /**
+     * @internal
+     *
+     * @param list<string> $input
+     * @param list<string> $arguments
+     * @param list<array{string, string}> $variables
+     */
+    public static function inMemory(
+        array $input,
+        bool $interactive,
+        array $arguments,
+        array $variables,
+        string $workingDirectory,
+    ): self {
+        return new self(InMemory::of(
+            $input,
+            $interactive,
+            $arguments,
+            $variables,
+            $workingDirectory,
+        ));
+    }
+
     /**
      * True if the environment running the script is an interactive terminal
      */
-    public function interactive(): bool;
+    public function interactive(): bool
+    {
+        return $this->implementation->interactive();
+    }
 
     /**
      * @param ?positive-int $length
      *
      * @return array{Attempt<Str>, self}
      */
-    public function read(?int $length = null): array;
+    public function read(?int $length = null): array
+    {
+        [$read, $implementation] = $this->implementation->read($length);
+
+        return [$read, new self($implementation)];
+    }
 
     /**
      * @return Attempt<self>
      */
-    public function output(Str $data): Attempt;
+    public function output(Str $data): Attempt
+    {
+        return $this
+            ->implementation
+            ->output($data)
+            ->map(static fn($implementation) => new self($implementation));
+    }
 
     /**
      * @return Attempt<self>
      */
-    public function error(Str $data): Attempt;
+    public function error(Str $data): Attempt
+    {
+        return $this
+            ->implementation
+            ->error($data)
+            ->map(static fn($implementation) => new self($implementation));
+    }
 
     /**
      * @return Sequence<string>
      */
-    public function arguments(): Sequence;
+    public function arguments(): Sequence
+    {
+        return $this->implementation->arguments();
+    }
 
     /**
      * @return Map<string, string>
      */
-    public function variables(): Map;
+    public function variables(): Map
+    {
+        return $this->implementation->variables();
+    }
 
     /**
      * @param int<0, 254> $code
      */
-    public function exit(int $code): self;
+    public function exit(int $code): self
+    {
+        return new self($this->implementation->exit($code));
+    }
 
     /**
      * @return Maybe<ExitCode>
      */
-    public function exitCode(): Maybe;
-    public function workingDirectory(): Path;
+    public function exitCode(): Maybe
+    {
+        return $this->implementation->exitCode();
+    }
+
+    public function workingDirectory(): Path
+    {
+        return $this->implementation->workingDirectory();
+    }
+
+    /**
+     * @internal
+     *
+     * @return Sequence<array{Str, 'output'|'error'}>
+     */
+    public function outputted(): Sequence
+    {
+        return $this->implementation->outputted();
+    }
 }
diff --git a/src/Environment/GlobalEnvironment.php b/src/Environment/GlobalEnvironment.php
index e17db19..8c55ff2 100644
--- a/src/Environment/GlobalEnvironment.php
+++ b/src/Environment/GlobalEnvironment.php
@@ -3,8 +3,7 @@
 
 namespace Innmind\CLI\Environment;
 
-use Innmind\CLI\Environment;
-use Innmind\TimeContinuum\Period;
+use Innmind\Time\Period;
 use Innmind\IO\{
     IO,
     Streams\Stream\Read,
@@ -21,8 +20,9 @@
 
 /**
  * @psalm-immutable
+ * @internal
  */
-final class GlobalEnvironment implements Environment
+final class GlobalEnvironment implements Implementation
 {
     /**
      * @param Output<'stdout'> $output
@@ -180,4 +180,10 @@ public function workingDirectory(): Path
     {
         return $this->workingDirectory;
     }
+
+    #[\Override]
+    public function outputted(): Sequence
+    {
+        return Sequence::of();
+    }
 }
diff --git a/src/Environment/Implementation.php b/src/Environment/Implementation.php
new file mode 100644
index 0000000..369585d
--- /dev/null
+++ b/src/Environment/Implementation.php
@@ -0,0 +1,68 @@
+<?php
+declare(strict_types = 1);
+
+namespace Innmind\CLI\Environment;
+
+use Innmind\Url\Path;
+use Innmind\Immutable\{
+    Map,
+    Sequence,
+    Str,
+    Attempt,
+    Maybe,
+};
+
+/**
+ * @psalm-immutable
+ * @internal
+ */
+interface Implementation
+{
+    /**
+     * True if the environment running the script is an interactive terminal
+     */
+    public function interactive(): bool;
+
+    /**
+     * @param ?positive-int $length
+     *
+     * @return array{Attempt<Str>, self}
+     */
+    public function read(?int $length = null): array;
+
+    /**
+     * @return Attempt<self>
+     */
+    public function output(Str $data): Attempt;
+
+    /**
+     * @return Attempt<self>
+     */
+    public function error(Str $data): Attempt;
+
+    /**
+     * @return Sequence<string>
+     */
+    public function arguments(): Sequence;
+
+    /**
+     * @return Map<string, string>
+     */
+    public function variables(): Map;
+
+    /**
+     * @param int<0, 254> $code
+     */
+    public function exit(int $code): self;
+
+    /**
+     * @return Maybe<ExitCode>
+     */
+    public function exitCode(): Maybe;
+    public function workingDirectory(): Path;
+
+    /**
+     * @return Sequence<array{Str, 'output'|'error'}>
+     */
+    public function outputted(): Sequence;
+}
diff --git a/src/Environment/InMemory.php b/src/Environment/InMemory.php
index 467b0ae..fefb21f 100644
--- a/src/Environment/InMemory.php
+++ b/src/Environment/InMemory.php
@@ -3,7 +3,6 @@
 
 namespace Innmind\CLI\Environment;
 
-use Innmind\CLI\Environment;
 use Innmind\Url\Path;
 use Innmind\Immutable\{
     Sequence,
@@ -16,21 +15,20 @@
 /**
  * Use this implementation for tests only
  * @psalm-immutable
+ * @internal
  */
-final class InMemory implements Environment
+final class InMemory implements Implementation
 {
     /**
      * @param Sequence<Str> $input
-     * @param Sequence<Str> $output
-     * @param Sequence<Str> $error
+     * @param Sequence<array{Str, 'output'|'error'}> $outputted
      * @param Sequence<string> $arguments
      * @param Map<string, string> $variables
      * @param Maybe<ExitCode> $exitCode
      */
     private function __construct(
         private Sequence $input,
-        private Sequence $output,
-        private Sequence $error,
+        private Sequence $outputted,
         private bool $interactive,
         private Sequence $arguments,
         private Map $variables,
@@ -57,7 +55,6 @@ public static function of(
         return new self(
             Sequence::of(...$input)->map(static fn($string) => Str::of($string, Str\Encoding::ascii)),
             Sequence::of(),
-            Sequence::of(),
             $interactive,
             Sequence::of(...$arguments),
             Map::of(...$variables),
@@ -95,8 +92,7 @@ public function read(?int $length = null): array
             $data->attempt(static fn() => new \LogicException('No input data specified')),
             new self(
                 $input,
-                $this->output,
-                $this->error,
+                $this->outputted,
                 $this->interactive,
                 $this->arguments,
                 $this->variables,
@@ -111,8 +107,10 @@ public function output(Str $data): Attempt
     {
         return Attempt::result(new self(
             $this->input,
-            ($this->output)($data->toEncoding(Str\Encoding::ascii)),
-            $this->error,
+            ($this->outputted)([
+                $data->toEncoding(Str\Encoding::ascii),
+                'output',
+            ]),
             $this->interactive,
             $this->arguments,
             $this->variables,
@@ -126,8 +124,10 @@ public function error(Str $data): Attempt
     {
         return Attempt::result(new self(
             $this->input,
-            $this->output,
-            ($this->error)($data->toEncoding(Str\Encoding::ascii)),
+            ($this->outputted)([
+                $data->toEncoding(Str\Encoding::ascii),
+                'error',
+            ]),
             $this->interactive,
             $this->arguments,
             $this->variables,
@@ -153,8 +153,7 @@ public function exit(int $code): self
     {
         return new self(
             $this->input,
-            $this->output,
-            $this->error,
+            $this->outputted,
             $this->interactive,
             $this->arguments,
             $this->variables,
@@ -175,25 +174,9 @@ public function workingDirectory(): Path
         return $this->workingDirectory;
     }
 
-    /**
-     * @return list<string>
-     */
-    public function outputs(): array
-    {
-        return $this
-            ->output
-            ->map(static fn($string) => $string->toString())
-            ->toList();
-    }
-
-    /**
-     * @return list<string>
-     */
-    public function errors(): array
+    #[\Override]
+    public function outputted(): Sequence
     {
-        return $this
-            ->error
-            ->map(static fn($string) => $string->toString())
-            ->toList();
+        return $this->outputted;
     }
 }
diff --git a/src/Exception/EachRowMustBeOfSameSize.php b/src/Exception/EachRowMustBeOfSameSize.php
deleted file mode 100644
index 32dc35e..0000000
--- a/src/Exception/EachRowMustBeOfSameSize.php
+++ /dev/null
@@ -1,8 +0,0 @@
-<?php
-declare(strict_types = 1);
-
-namespace Innmind\CLI\Exception;
-
-final class EachRowMustBeOfSameSize extends DomainException
-{
-}
diff --git a/src/Exception/LogicException.php b/src/Exception/LogicException.php
deleted file mode 100644
index 583b01e..0000000
--- a/src/Exception/LogicException.php
+++ /dev/null
@@ -1,8 +0,0 @@
-<?php
-declare(strict_types = 1);
-
-namespace Innmind\CLI\Exception;
-
-final class LogicException extends \LogicException implements Exception
-{
-}
diff --git a/src/Main.php b/src/Main.php
index 32e8b92..7568279 100644
--- a/src/Main.php
+++ b/src/Main.php
@@ -25,7 +25,7 @@ final public function __construct(?Config $config = null)
     {
         $config ??= Config::new();
         $os = Factory::build($config);
-        $env = Environment\GlobalEnvironment::of($config->io());
+        $env = Environment::global($config->io());
 
         try {
             $env = $this->main($env, $os)->unwrap();
diff --git a/tests/Command/Pattern/InputsTest.php b/tests/Command/Pattern/InputsTest.php
index 2511fdc..66eb447 100644
--- a/tests/Command/Pattern/InputsTest.php
+++ b/tests/Command/Pattern/InputsTest.php
@@ -18,6 +18,6 @@ public function testThrowWhenPatternNotRecognized()
         $this->expectException(PatternNotRecognized::class);
         $this->expectExceptionMessage('_foo_');
 
-        (new Inputs)(Usage::of('name'), Str::of('_foo_'))->unwrap();
+        $_ = (new Inputs)(Usage::of('name'), Str::of('_foo_'))->unwrap();
     }
 }
diff --git a/tests/Command/Pattern/OptionFlagTest.php b/tests/Command/Pattern/OptionFlagTest.php
index 476d439..069f582 100644
--- a/tests/Command/Pattern/OptionFlagTest.php
+++ b/tests/Command/Pattern/OptionFlagTest.php
@@ -77,7 +77,7 @@ public function testParse()
         );
 
         $this->assertSame(['watev', 'bar', '--unknown', 'baz'], $arguments->toList());
-        $this->assertCount(1, $options);
+        $this->assertSame(1, $options->size());
         $this->assertSame('', $options->get('foo')->match(
             static fn($value) => $value,
             static fn() => null,
diff --git a/tests/Command/Pattern/OptionWithValueTest.php b/tests/Command/Pattern/OptionWithValueTest.php
index a63c5df..d711257 100644
--- a/tests/Command/Pattern/OptionWithValueTest.php
+++ b/tests/Command/Pattern/OptionWithValueTest.php
@@ -77,7 +77,7 @@ public function testParseShortOption()
         );
 
         $this->assertSame(['watev', 'bar'], $arguments->toList());
-        $this->assertCount(1, $options);
+        $this->assertSame(1, $options->size());
         $this->assertSame('baz', $options->get('foo')->match(
             static fn($value) => $value,
             static fn() => null,
@@ -97,7 +97,7 @@ public function testParseShortOptionWithValueInNextArgument()
         );
 
         $this->assertSame(['watev', 'bar'], $arguments->toList());
-        $this->assertCount(1, $options);
+        $this->assertSame(1, $options->size());
         $this->assertSame('baz', $options->get('foo')->match(
             static fn($value) => $value,
             static fn() => null,
@@ -117,7 +117,7 @@ public function testParseShortOptionWithValueInNextArgumentButNoNextValue()
         );
 
         $this->assertSame(['watev'], $arguments->toList());
-        $this->assertCount(1, $options);
+        $this->assertSame(1, $options->size());
         $this->assertSame('', $options->get('foo')->match(
             static fn($value) => $value,
             static fn() => null,
@@ -137,7 +137,7 @@ public function testParseLongOption()
         );
 
         $this->assertSame(['watev', 'bar'], $arguments->toList());
-        $this->assertCount(1, $options);
+        $this->assertSame(1, $options->size());
         $this->assertSame('baz', $options->get('foo')->match(
             static fn($value) => $value,
             static fn() => null,
diff --git a/tests/Command/Pattern/OptionalArgumentTest.php b/tests/Command/Pattern/OptionalArgumentTest.php
index 302a84c..d9da036 100644
--- a/tests/Command/Pattern/OptionalArgumentTest.php
+++ b/tests/Command/Pattern/OptionalArgumentTest.php
@@ -79,7 +79,7 @@ public function testParse(): BlackBox\Proof
                     Map::of(),
                 );
 
-                $this->assertCount(1, $parsedArguments);
+                $this->assertSame(1, $parsedArguments->size());
                 $this->assertSame($strings[0], $parsedArguments->get('foo')->match(
                     static fn($value) => $value,
                     static fn() => null,
@@ -104,7 +104,7 @@ public function testParseWhenNoMoreArguments()
             Map::of(),
         );
 
-        $this->assertCount(0, $parsedArguments);
+        $this->assertSame(0, $parsedArguments->size());
         $this->assertNull($parsedArguments->get('foo')->match(
             static fn($value) => $value,
             static fn() => null,
diff --git a/tests/Command/Pattern/RequiredArgumentTest.php b/tests/Command/Pattern/RequiredArgumentTest.php
index 0d84f80..240cca8 100644
--- a/tests/Command/Pattern/RequiredArgumentTest.php
+++ b/tests/Command/Pattern/RequiredArgumentTest.php
@@ -80,7 +80,7 @@ public function testParse(): BlackBox\Proof
                     Map::of(),
                 );
 
-                $this->assertCount(1, $parsedArguments);
+                $this->assertSame(1, $parsedArguments->size());
                 $this->assertSame($strings[0], $parsedArguments->get('foo')->match(
                     static fn($value) => $value,
                     static fn() => null,
diff --git a/tests/Command/PatternTest.php b/tests/Command/PatternTest.php
index 33e9fd0..4bcfe77 100644
--- a/tests/Command/PatternTest.php
+++ b/tests/Command/PatternTest.php
@@ -67,6 +67,6 @@ public function testParse()
 
         $this->assertSame('first', $arguments->get('foo'));
         $this->assertSame('second', $arguments->get('bar'));
-        $this->assertCount(0, $arguments->pack());
+        $this->assertSame(0, $arguments->pack()->size());
     }
 }
diff --git a/tests/Command/UsageTest.php b/tests/Command/UsageTest.php
index a82483b..1f36da0 100644
--- a/tests/Command/UsageTest.php
+++ b/tests/Command/UsageTest.php
@@ -55,6 +55,7 @@ public function testMatchesItsOwnName(): BlackBox\Proof
                 $this->names(),
             )
             ->filter(static fn($a, $b) => $a !== $b)
+            ->filter(static fn($a, $b) => !\str_starts_with($a, $b))
             ->prove(function($a, $b) {
                 $usage = Usage::parse($a);
 
@@ -135,6 +136,10 @@ public function testDoesntMatchWhenOwnNameDoesntExplicitlyStartWithSubset(): Bla
                 Set::integers()->between(1, 10),
                 Set::integers()->between(1, 10),
             )
+            ->filter(static fn($name, $start, $shrink) => !\str_starts_with(
+                $name,
+                \mb_substr($name, $start, $shrink),
+            ))
             ->prove(function($name, $start, $shrink) {
                 $usage = Usage::parse($name);
                 $shrunk = \mb_substr($name, $start, $shrink);
@@ -156,23 +161,8 @@ private function names(): Set
         return Set::strings()
             ->madeOf(
                 Set::strings()
-                    ->unicode()
-                    ->char()
-                    ->filter(
-                        static fn($char) => !\in_array(
-                            $char,
-                            [
-                                ':',
-                                ' ',
-                                "\n",
-                                "\r",
-                                \chr(11),
-                                \chr(0),
-                                "\t",
-                            ],
-                            true,
-                        ),
-                    ),
+                    ->chars()
+                    ->alphanumerical(),
             )
             ->between(1, 10);
     }
diff --git a/tests/CommandsTest.php b/tests/CommandsTest.php
index 7afc51a..bb9afba 100644
--- a/tests/CommandsTest.php
+++ b/tests/CommandsTest.php
@@ -55,7 +55,7 @@ public function usage(): Usage
                 return Usage::parse('watch container [output] --foo');
             }
         });
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'foo', '--foo', 'bar'],
@@ -105,7 +105,7 @@ public function usage(): Usage
                 }
             },
         );
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'watch', 'foo', '--foo', 'bar'],
@@ -145,7 +145,7 @@ public function usage(): Usage
                 }
             },
         );
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'watch', 'foo', '--foo', 'bar'],
@@ -185,7 +185,7 @@ public function usage(): Usage
                 }
             },
         );
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'foo'],
@@ -225,7 +225,7 @@ public function usage(): Usage
                 }
             },
         );
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'w'],
@@ -265,7 +265,7 @@ public function usage(): Usage
                 }
             },
         );
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'f:b:b'],
@@ -305,7 +305,7 @@ public function usage(): Usage
                 }
             },
         );
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'bar'],
@@ -324,7 +324,11 @@ public function usage(): Usage
                 " foo    \n",
                 " watch  \n",
             ],
-            $env->errors(),
+            $env
+                ->outputted()
+                ->filter(static fn($pair) => $pair[1] === 'error')
+                ->map(static fn($pair) => $pair[0]->toString())
+                ->toList(),
         );
     }
 
@@ -354,7 +358,7 @@ public function usage(): Usage
                 }
             },
         );
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'ba'],
@@ -373,7 +377,11 @@ public function usage(): Usage
                 " bar  \n",
                 " baz  \n",
             ],
-            $env->errors(),
+            $env
+                ->outputted()
+                ->filter(static fn($pair) => $pair[1] === 'error')
+                ->map(static fn($pair) => $pair[0]->toString())
+                ->toList(),
         );
     }
 
@@ -396,7 +404,7 @@ public function usage(): Usage
 USAGE);
             }
         });
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console'],
@@ -412,7 +420,11 @@ public function usage(): Usage
         ));
         $this->assertSame(
             ['usage: bin/console watch container [output] --foo --help --no-interaction'."\n\nFoo\n\nBar\n"],
-            $env->errors(),
+            $env
+                ->outputted()
+                ->filter(static fn($pair) => $pair[1] === 'error')
+                ->map(static fn($pair) => $pair[0]->toString())
+                ->toList(),
         );
     }
 
@@ -429,7 +441,7 @@ public function usage(): Usage
                 return Usage::parse('watch container [output] --foo');
             }
         });
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'foo', '--foo', 'bar'],
@@ -439,7 +451,7 @@ public function usage(): Usage
 
         $this->expectException(\Exception::class);
 
-        $run($env)->unwrap();
+        $_ = $run($env)->unwrap();
     }
 
     public function testDisplayUsageWhenHelpOptionFound()
@@ -461,7 +473,7 @@ public function usage(): Usage
 USAGE);
             }
         });
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', '--help'],
@@ -477,7 +489,11 @@ public function usage(): Usage
         ));
         $this->assertSame(
             ['usage: bin/console watch container [output] --foo --help --no-interaction'."\n\nFoo\n\nBar\n"],
-            $env->outputs(),
+            $env
+                ->outputted()
+                ->filter(static fn($pair) => $pair[1] === 'output')
+                ->map(static fn($pair) => $pair[0]->toString())
+                ->toList(),
         );
     }
 
@@ -507,7 +523,7 @@ public function usage(): Usage
                 }
             },
         );
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'help'],
@@ -526,7 +542,11 @@ public function usage(): Usage
                 " foo    Description\n",
                 " watch  Watch dependency injection\n",
             ],
-            $env->outputs(),
+            $env
+                ->outputted()
+                ->filter(static fn($pair) => $pair[1] === 'output')
+                ->map(static fn($pair) => $pair[0]->toString())
+                ->toList(),
         );
     }
 
@@ -556,7 +576,7 @@ public function usage(): Usage
                 }
             },
         );
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console'],
@@ -572,7 +592,11 @@ public function usage(): Usage
         ));
         $this->assertSame(
             [" foo    \n", " watch  \n"],
-            $env->errors(),
+            $env
+                ->outputted()
+                ->filter(static fn($pair) => $pair[1] === 'error')
+                ->map(static fn($pair) => $pair[0]->toString())
+                ->toList(),
         );
     }
 
@@ -603,7 +627,7 @@ public function usage(): Usage
                 }
             },
         );
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'help'],
@@ -622,7 +646,11 @@ public function usage(): Usage
                 " foo    \n",
                 " watch  \n",
             ],
-            $env->outputs(),
+            $env
+                ->outputted()
+                ->filter(static fn($pair) => $pair[1] === 'output')
+                ->map(static fn($pair) => $pair[0]->toString())
+                ->toList(),
         );
     }
 
@@ -647,7 +675,7 @@ public function usage(): Usage
                 }
             },
         );
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', '--help'],
@@ -670,7 +698,11 @@ public function usage(): Usage
 
                 USAGE,
             ],
-            $env->outputs(),
+            $env
+                ->outputted()
+                ->filter(static fn($pair) => $pair[1] === 'output')
+                ->map(static fn($pair) => $pair[0]->toString())
+                ->toList(),
         );
     }
 
@@ -713,7 +745,7 @@ public function usage(): Usage
                 }
             };
         }));
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'watch', 'foo', '--foo', 'bar'],
@@ -784,7 +816,7 @@ public function usage(): Usage
                 }
             };
         }));
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'ba'],
@@ -856,7 +888,7 @@ public function usage(): Usage
                 }
             };
         }));
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['bin/console', 'unknown'],
diff --git a/tests/Environment/GlobalEnvironmentTest.php b/tests/Environment/GlobalEnvironmentTest.php
index 108bc66..7b4b71b 100644
--- a/tests/Environment/GlobalEnvironmentTest.php
+++ b/tests/Environment/GlobalEnvironmentTest.php
@@ -3,10 +3,7 @@
 
 namespace Tests\Innmind\CLI\Environment;
 
-use Innmind\CLI\{
-    Environment\GlobalEnvironment,
-    Environment,
-};
+use Innmind\CLI\Environment\GlobalEnvironment;
 use Innmind\IO\IO;
 use Innmind\Url\Path;
 use Innmind\Immutable\{
@@ -25,11 +22,6 @@ public function setUp(): void
         $this->env = GlobalEnvironment::of(IO::fromAmbientAuthority());
     }
 
-    public function testInterface()
-    {
-        $this->assertInstanceOf(Environment::class, $this->env);
-    }
-
     public function testInteractive()
     {
         // can't prove via a test that the env can be interactive as tests are
@@ -63,7 +55,6 @@ public function testExitCode()
     {
         $this->assertEquals(Maybe::nothing(), $this->env->exitCode());
         $env = $this->env->exit(1);
-        $this->assertInstanceOf(Environment::class, $env);
         $this->assertSame(1, $env->exitCode()->match(
             static fn($code) => $code->toInt(),
             static fn() => null,
diff --git a/tests/MainTest.php b/tests/MainTest.php
index 0af3b68..842b4ff 100644
--- a/tests/MainTest.php
+++ b/tests/MainTest.php
@@ -72,7 +72,7 @@ public function testEcho()
             $process
                 ->output()
                 ->map(static fn($chunk) => $chunk->data())
-                ->fold(new Concat)
+                ->fold(Concat::monoid)
                 ->toString(),
         );
     }
@@ -88,7 +88,7 @@ public function testThrow()
                     ->withEnvironment('PATH', $_SERVER['PATH']),
             )
             ->unwrap();
-        $process->output()->foreach(function($chunk): void {
+        $_ = $process->output()->foreach(function($chunk): void {
             $this->assertSame(Type::error, $chunk->type());
         });
 
@@ -97,7 +97,7 @@ public function testThrow()
             $process
                 ->output()
                 ->map(static fn($chunk) => $chunk->data())
-                ->fold(new Concat)
+                ->fold(Concat::monoid)
                 ->toString(),
         )
             ->split("\n")
@@ -105,11 +105,11 @@ public function testThrow()
 
         $this->assertCount(6, $output);
         $this->assertSame(
-            "Innmind\CLI\Exception\LogicException(waaat, 0)",
+            'LogicException(waaat, 0)',
             $output[0]->toString(),
         );
         $this->assertSame(
-            "$cwd/fixtures/thrower.php:18",
+            "$cwd/fixtures/thrower.php:17",
             $output[1]->toString(),
         );
         $this->assertSame(
@@ -133,7 +133,7 @@ public function testThrow()
             $output[3]->substring(-28 - \strlen($cwd))->toString(),
         );
         $this->assertSame(
-            "Innmind\CLI\Main->__construct() at $cwd/fixtures/thrower.php:15",
+            "Innmind\CLI\Main->__construct() at $cwd/fixtures/thrower.php:14",
             $output[4]->toString(),
         );
         $this->assertSame(
diff --git a/tests/Question/ChoiceQuestionTest.php b/tests/Question/ChoiceQuestionTest.php
index 123d6ea..75197db 100644
--- a/tests/Question/ChoiceQuestionTest.php
+++ b/tests/Question/ChoiceQuestionTest.php
@@ -22,7 +22,7 @@ public function testInvoke()
                 (2, 3)
                 ('bar', 3),
         );
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [' foo,  ', "2\n"],
             true,
             [],
@@ -37,7 +37,7 @@ public function testInvoke()
         );
 
         $this->assertInstanceOf(Map::class, $response);
-        $this->assertCount(2, $response);
+        $this->assertSame(2, $response->size());
         $this->assertSame('bar', $response->get('foo')->match(
             static fn($value) => $value,
             static fn() => null,
@@ -55,7 +55,10 @@ public function testInvoke()
                 "[bar] 3\n",
                 '> ',
             ],
-            $env->outputs(),
+            $env
+                ->outputted()
+                ->map(static fn($pair) => $pair[0]->toString())
+                ->toList(),
         );
     }
 
@@ -63,7 +66,7 @@ public function testReturnNothingWhenEnvNonInteractive()
     {
         $question = ChoiceQuestion::of('watev', Map::of());
 
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             false,
             [],
@@ -83,7 +86,7 @@ public function testReturnNothingWhenOptionToSpecifyNoInteractionIsRequired()
     {
         $question = ChoiceQuestion::of('watev', Map::of());
 
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['foo', '--no-interaction', 'bar'],
diff --git a/tests/Question/QuestionTest.php b/tests/Question/QuestionTest.php
index 9f0bd1b..f968ea1 100644
--- a/tests/Question/QuestionTest.php
+++ b/tests/Question/QuestionTest.php
@@ -15,7 +15,7 @@ class QuestionTest extends TestCase
     public function testInvoke()
     {
         $question = Question::of('message');
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             ['f', "oo\n"],
             true,
             [],
@@ -33,7 +33,10 @@ public function testInvoke()
         $this->assertSame('foo', $response->toString());
         $this->assertSame(
             ['message '],
-            $env->outputs(),
+            $env
+                ->outputted()
+                ->map(static fn($pair) => $pair[0]->toString())
+                ->toList(),
         );
     }
 
@@ -41,7 +44,7 @@ public function testReturnNothingWhenEnvNonInteractive()
     {
         $question = Question::of('watev');
 
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             false,
             [],
@@ -61,7 +64,7 @@ public function testReturnNothingWhenOptionToSpecifyNoInteractionIsRequired()
     {
         $question = Question::of('watev');
 
-        $env = Environment\InMemory::of(
+        $env = Environment::inMemory(
             [],
             true,
             ['foo', '--no-interaction', 'bar'],