Add script detection, env shebang parser, and opt-in content guessing

tests/test_cli.py

@@ -74,6 +74,7 @@ class TestFileInput:
             path=str(file),
             content="x = 1\n",
             explicit_type=None,
+            guess_content=False,
         )
 
     def test_render_called_with_correct_options(self, tmp_file) -> None:
@@ -180,6 +181,7 @@ class TestStdinInput:
             path=None,
             content="hello\n",
             explicit_type=None,
+            guess_content=False,
         )
 
     def test_stdin_shows_tty_prompt(self) -> None:
@@ -216,6 +218,7 @@ class TestTypeOverride:
 
         _, kwargs = mock_detect_type.call_args
         assert kwargs["explicit_type"] == "json"
+        assert kwargs["guess_content"] is False
 
     def test_explicit_type_short_flag(self, tmp_file) -> None:
         file = tmp_file("def foo(): pass\n", suffix=".txt")
@@ -236,6 +239,28 @@ class TestThemeOption:
         assert result.exit_code == 0
 
 
+class TestGuessContentOption:
+    """Tests for the guess-content flag."""
+
+    def test_guess_content_is_forwarded(self) -> None:
+        with patch("rp.cli.detect_type") as mock_detect_type:
+            mock_detect_type.return_value = "diff"
+            with patch("rp.cli.render"):
+                runner.invoke(app, ["--guess-content", "--no-pager"], input="hello\n")
+
+        _, kwargs = mock_detect_type.call_args
+        assert kwargs["guess_content"] is True
+
+    def test_guess_content_disabled_by_default(self) -> None:
+        with patch("rp.cli.detect_type") as mock_detect_type:
+            mock_detect_type.return_value = "text"
+            with patch("rp.cli.render"):
+                runner.invoke(app, ["--no-pager"], input="hello\n")
+
+        _, kwargs = mock_detect_type.call_args
+        assert kwargs["guess_content"] is False
+
+
 class TestLineNumbersOption:
     """Tests for the line number flags."""