Fix: use DARK_GRAY for unmapped content type groups (fixes #1243)

Root cause: color_by_group in magika_client.py did not have entries for
"text", "unknown", "application", "font", and "inode" groups, so they
all fell back to colors.WHITE (\033[1;37m — bright white). On
light-background terminals this produces nearly invisible output.

Fix: add explicit "text" and "unknown" mappings to DARK_GRAY, and
change the dict's default fallback from colors.WHITE to colors.DARK_GRAY.
DARK_GRAY (\033[1;30m) is visible on both dark and light terminals.

Regression test added: verifies that plain-text file output uses
DARK_GRAY and not the bright-white code that breaks on white backgrounds.

Author: shivamtiwari3

python/src/magika/cli/magika_client.py

@@ -255,6 +255,8 @@ def main(
         "image": colors.YELLOW,
         "video": colors.YELLOW,
         "code": colors.LIGHT_BLUE,
+        "text": colors.DARK_GRAY,
+        "unknown": colors.DARK_GRAY,
     }
 
     # updated only when we need to output in JSON format
@@ -309,7 +311,7 @@ def main(
 
                     if with_colors:
                         start_color = color_by_group.get(
-                            result.prediction.output.group, colors.WHITE
+                            result.prediction.output.group, colors.DARK_GRAY
                         )
                         end_color = colors.RESET
                 else:

python/tests/test_python_magika_client.py

@@ -13,8 +13,11 @@
 # limitations under the License.
 
 import subprocess
+import tempfile
 from pathlib import Path
 
+from magika import colors
+
 
 def test_python_magika_client() -> None:
     python_root_dir = Path(__file__).parent.parent
@@ -29,3 +32,46 @@ def test_python_magika_client() -> None:
     # quick test to check there are no crashes
     cmd = [str(python_magika_client_path), str(python_magika_client_path)]
     subprocess.run(cmd, capture_output=True, check=True)
+
+
+def test_colored_output_visible_on_light_background_terminals() -> None:
+    """Regression test for https://github.com/google/magika/issues/1243.
+
+    The fallback color for content type groups not explicitly mapped in
+    color_by_group must not be bright white (\033[1;37m), which is nearly
+    invisible on light-background terminals. DARK_GRAY (\033[1;30m) is
+    visible on both dark and light backgrounds.
+    """
+    python_root_dir = Path(__file__).parent.parent
+    python_magika_client_path = (
+        python_root_dir / "src" / "magika" / "cli" / "magika_client.py"
+    ).resolve()
+
+    # Write a plain text file — classified as group="text", which previously
+    # fell through to the bright-white fallback color.
+    with tempfile.NamedTemporaryFile(suffix=".txt", mode="w", delete=False) as tmp:
+        tmp.write("Hello, world!\n")
+        tmp_path = Path(tmp.name)
+
+    try:
+        result = subprocess.run(
+            [str(python_magika_client_path), "--colors", str(tmp_path)],
+            capture_output=True,
+            text=True,
+            check=True,
+        )
+        output = result.stdout
+        # The output must not contain the bright-white ANSI code, which is
+        # invisible on white/light-background terminals.
+        assert colors.WHITE not in output, (
+            f"Output used bright-white ({repr(colors.WHITE)}), which is "
+            "invisible on light-background terminals. Use DARK_GRAY instead."
+        )
+        # DARK_GRAY must be present so that content types in the "text" group
+        # (and any other unmapped group) are readable on light terminals.
+        assert colors.DARK_GRAY in output, (
+            f"Expected DARK_GRAY ({repr(colors.DARK_GRAY)}) in colored output "
+            "for a plain-text file, but it was not found."
+        )
+    finally:
+        tmp_path.unlink(missing_ok=True)