diff --git a/src/Cli/BrefSpinner.php b/src/Cli/BrefSpinner.php
index f2ba1f2..1871732 100644
--- a/src/Cli/BrefSpinner.php
+++ b/src/Cli/BrefSpinner.php
@@ -166,7 +166,9 @@ private function overwrite(string $message): void
                 $this->output->write(Styles::gray('press [?] for verbose logs'));
             }
         } else {
-            $this->output->writeln($message);
+            // Our colors are raw ANSI escape codes (see `Styles`), which Symfony does not strip on
+            // its own when the output is not decorated (a pipe, a redirection to a file, CI...).
+            $this->output->writeln($this->output->isDecorated() ? $message : Styles::strip($message));
         }
     }
 
diff --git a/src/Cli/IO.php b/src/Cli/IO.php
index e3b88b1..b156937 100644
--- a/src/Cli/IO.php
+++ b/src/Cli/IO.php
@@ -178,8 +178,7 @@ private static function writeToLogsFile(string|array $messages): void
         if (! self::$logsFileResource) return;
 
         $message = is_array($messages) ? implode(PHP_EOL, $messages) : $messages;
-        // Strip ANSI
-        $message = (string) preg_replace('/\x1b\[[0-9;]*m/', '', $message);
+        $message = Styles::strip($message);
         foreach (explode(PHP_EOL, $message) as $line) {
             if (empty(trim($line))) continue;
             fwrite(self::$logsFileResource, $line . PHP_EOL);
@@ -216,6 +215,13 @@ private static function safeWrite(string|array $messages): void
             $messages = explode(PHP_EOL, $messages);
         }
 
+        // Our own colors are raw ANSI escape codes (see `Styles`), not Symfony formatter tags, so
+        // Symfony does not strip them on its own when the output is not decorated (NO_COLOR, a pipe,
+        // a redirection to a file...). Strip them here so piped/redirected output stays clean.
+        if (! self::$output->isDecorated()) {
+            $messages = array_map(Styles::strip(...), $messages);
+        }
+
         // Symfony `StreamOutput` is not compatible with non-blocking mode
         // (in that case `fwrite` returns the number of bytes written, which Symfony ignores)
         // Amphp sets STDOUT and STDERR to non-blocking mode, so we need to set them back to blocking mode here.
diff --git a/src/Cli/Styles.php b/src/Cli/Styles.php
index 1b7c46e..c6b7c19 100644
--- a/src/Cli/Styles.php
+++ b/src/Cli/Styles.php
@@ -119,4 +119,13 @@ public static function gray(string $text): string
     {
         return "\e[90m{$text}\e[39m";
     }
+
+    /**
+     * Removes ANSI escape codes, for when the text ends up somewhere that does not render them
+     * (a piped/redirected output, a log file...).
+     */
+    public static function strip(string $text): string
+    {
+        return (string) preg_replace('/\x1b\[[0-9;]*m/', '', $text);
+    }
 }
\ No newline at end of file
diff --git a/tests/Cli/IOTest.php b/tests/Cli/IOTest.php
new file mode 100644
index 0000000..83463ca
--- /dev/null
+++ b/tests/Cli/IOTest.php
@@ -0,0 +1,106 @@
+<?php declare(strict_types=1);
+
+namespace Bref\Cli\Test\Cli;
+
+use Bref\Cli\Cli\IO;
+use PHPUnit\Framework\TestCase;
+use RuntimeException;
+use Symfony\Component\Console\Input\ArrayInput;
+use Symfony\Component\Console\Output\BufferedOutput;
+
+/**
+ * `IO` writes its own decorations (spinner, verbose logs, warnings, errors) using raw ANSI escape
+ * codes (see `Styles`), not Symfony formatter tags. Symfony only strips formatter tags when the
+ * output is not decorated, so `IO` has to strip its own raw codes itself, otherwise a piped or
+ * redirected output (or CI) gets polluted with escape codes.
+ */
+class IOTest extends TestCase
+{
+    protected function tearDown(): void
+    {
+        IO::stop();
+    }
+
+    public function test_warnings_and_errors_have_no_escape_codes_when_not_decorated(): void
+    {
+        $output = new BufferedOutput(decorated: false);
+        IO::init(new ArrayInput([]), $output);
+
+        IO::warning('Something to pay attention to');
+        IO::error(new RuntimeException('The command failed'));
+
+        $display = $output->fetch();
+
+        $this->assertStringNotContainsString("\e[", $display);
+        $this->assertStringContainsString('Something to pay attention to', $display);
+        $this->assertStringContainsString('The command failed', $display);
+    }
+
+    public function test_warnings_and_errors_keep_colors_when_decorated(): void
+    {
+        $output = new BufferedOutput(decorated: true);
+        IO::init(new ArrayInput([]), $output);
+
+        IO::warning('Something to pay attention to');
+
+        $this->assertStringContainsString("\e[", $output->fetch());
+    }
+
+    public function test_the_spinner_has_no_escape_codes_when_not_decorated(): void
+    {
+        $output = new BufferedOutput(decorated: false);
+        IO::init(new ArrayInput([]), $output);
+
+        IO::spin('starting command');
+        IO::spin('running');
+        IO::spinClear();
+
+        $display = $output->fetch();
+
+        $this->assertStringNotContainsString("\e[", $display);
+        $this->assertStringContainsString('starting command', $display);
+        $this->assertStringContainsString('running', $display);
+    }
+
+    public function test_the_spinner_keeps_colors_when_decorated(): void
+    {
+        $output = new BufferedOutput(decorated: true);
+        IO::init(new ArrayInput([]), $output);
+
+        IO::spin('starting command');
+        IO::spinClear();
+
+        $this->assertStringContainsString("\e[", $output->fetch());
+    }
+
+    /**
+     * Verbose mode is forced on for non-interactive environments (CI, a piped output...), so its
+     * lines are exactly the kind of decoration that must stay clean when not decorated.
+     */
+    public function test_verbose_logs_have_no_escape_codes_when_not_decorated(): void
+    {
+        $output = new BufferedOutput(decorated: false);
+        IO::init(new ArrayInput([]), $output);
+
+        IO::verbose('Diagnostic detail');
+
+        $display = $output->fetch();
+
+        $this->assertStringNotContainsString("\e[", $display);
+        $this->assertStringContainsString('Diagnostic detail', $display);
+    }
+
+    /**
+     * The command's own output (e.g. what `bref command` prints from the deployed application)
+     * is never styled by the CLI, and must stay exactly as it is regardless of decoration.
+     */
+    public function test_plain_writeln_is_untouched(): void
+    {
+        $output = new BufferedOutput(decorated: false);
+        IO::init(new ArrayInput([]), $output);
+
+        IO::writeln('Hello from the deployed application');
+
+        $this->assertSame("Hello from the deployed application\n", $output->fetch());
+    }
+}
diff --git a/tests/Cli/StylesTest.php b/tests/Cli/StylesTest.php
new file mode 100644
index 0000000..960d1e1
--- /dev/null
+++ b/tests/Cli/StylesTest.php
@@ -0,0 +1,22 @@
+<?php declare(strict_types=1);
+
+namespace Bref\Cli\Test\Cli;
+
+use Bref\Cli\Cli\Styles;
+use PHPUnit\Framework\TestCase;
+
+class StylesTest extends TestCase
+{
+    public function test_strip_removes_ansi_escape_codes(): void
+    {
+        $this->assertSame(
+            'bold red gray plain',
+            Styles::strip(Styles::bold('bold') . ' ' . Styles::red('red') . ' ' . Styles::gray('gray') . ' plain'),
+        );
+    }
+
+    public function test_strip_leaves_text_without_escape_codes_untouched(): void
+    {
+        $this->assertSame('plain text', Styles::strip('plain text'));
+    }
+}