Zoom only affects the main window — secondary windows cannot be zoomed at all

Environment

• Claude for Mac 1.24012.9 (03c61d)
• macOS 12.7.4 (Monterey, build 21H1123)

Description

Text zoom applies only to the main application window. A secondary window cannot be zoomed by any means, leaving two side-by-side sessions stuck at different text sizes.

Steps to reproduce

1. Open a session — this becomes the main window
2. Open a second session in a new window
3. Focus the second window (verified focused: its traffic-light buttons are colored while the first window's are grey)
4. Press <kbd>⌘</kbd><kbd>+</kbd> / <kbd>⌘</kbd><kbd>−</kbd>, or use View → Zoom In / Zoom Out

Expected: the focused window zooms.

Actual: the main window zooms. The focused secondary window is completely unaffected.

Additional findings

• Reproduces through the menu bar as well as the keyboard, so this is not a keyboard-focus routing issue.
• Clicking directly into the conversation area (rather than the message input) does not help.
• Closing the main window does not promote the secondary window — the remaining window still cannot be zoomed by any method.
• <kbd>⌘</kbd><kbd>B</kbd> (toggle sidebar) works correctly on the focused secondary window, so window-level commands are reaching it. Zoom specifically is not.

That last point seems like the useful one: other window commands route to the focused window correctly, so zoom appears to be bound to the main window rather than the focused one.

Impact

Running two sessions side by side is a core workflow. Currently one of them is permanently stuck at whatever size it opened at, with no workaround inside the app. The only fallback is the macOS system-wide Accessibility zoom.