diff --git a/bin/notfair-content-calendar b/bin/notfair-content-calendar
index ce33bd23..45eaad25 100755
--- a/bin/notfair-content-calendar
+++ b/bin/notfair-content-calendar
@@ -359,6 +359,13 @@ def _port_in_use(port: int, host: str = "127.0.0.1") -> bool:
             return False
 
 
+def _should_auto_open(no_open: bool, platform: str, display: str) -> bool:
+    """Whether to auto-open the browser. Honors --no-open on every platform."""
+    if no_open:
+        return False
+    return bool(display) or platform == "darwin" or platform == "win32"
+
+
 def main(argv=None) -> int:
     parser = argparse.ArgumentParser(prog="notfair-content-calendar")
     parser.add_argument("--port", type=int, default=DEFAULT_PORT)
@@ -396,7 +403,7 @@ def main(argv=None) -> int:
     print(f"Reading: {calendar_path}")
     print("Ctrl+C to stop.")
 
-    if not args.no_open and os.environ.get("DISPLAY", "") or sys.platform == "darwin" or sys.platform == "win32":
+    if _should_auto_open(args.no_open, sys.platform, os.environ.get("DISPLAY", "")):
         # Open in a thread so we don't block startup if the browser command stalls.
         threading.Thread(target=lambda: (time.sleep(0.2), webbrowser.open(url)), daemon=True).start()
 
diff --git a/test/unit/test_content_calendar_auto_open.py b/test/unit/test_content_calendar_auto_open.py
new file mode 100644
index 00000000..7240dd2c
--- /dev/null
+++ b/test/unit/test_content_calendar_auto_open.py
@@ -0,0 +1,38 @@
+import unittest
+import importlib.util
+from importlib.machinery import SourceFileLoader
+import sys
+from pathlib import Path
+
+# bin script has no .py extension, so give spec an explicit source loader.
+script_path = Path(__file__).parent.parent.parent / 'bin' / 'notfair-content-calendar'
+loader = SourceFileLoader("notfair_content_calendar", str(script_path))
+spec = importlib.util.spec_from_file_location("notfair_content_calendar", str(script_path), loader=loader)
+mod = importlib.util.module_from_spec(spec)
+sys.modules["notfair_content_calendar"] = mod
+spec.loader.exec_module(mod)
+
+should_auto_open = mod._should_auto_open
+
+
+class TestShouldAutoOpen(unittest.TestCase):
+    def test_no_open_suppresses_on_every_platform(self):
+        # --no-open must win on macOS and Windows too, not just headless Linux.
+        for platform in ("darwin", "win32", "linux"):
+            self.assertFalse(
+                should_auto_open(no_open=True, platform=platform, display=""),
+                f"--no-open should suppress auto-open on {platform}",
+            )
+        self.assertFalse(should_auto_open(no_open=True, platform="linux", display=":0"))
+
+    def test_default_opens_where_a_gui_exists(self):
+        self.assertTrue(should_auto_open(False, "darwin", ""))
+        self.assertTrue(should_auto_open(False, "win32", ""))
+        self.assertTrue(should_auto_open(False, "linux", ":0"))
+
+    def test_headless_linux_does_not_open(self):
+        self.assertFalse(should_auto_open(False, "linux", ""))
+
+
+if __name__ == "__main__":
+    unittest.main()