Hmbown/CodeWhale · error

window pinning is only supported on Windows

Error message

window pinning is only supported on Windows

What it means

This error is thrown by the non-Windows stub implementation of the window control module. Window pinning (always-on-top / taskbar pin toggle) is implemented only against the Win32 API; on all other platforms `start_toggle` immediately bails with this message instead of performing any operation. It surfaces whenever the pin toggle is invoked on a platform without native support.

Solutions

1. Do not invoke the pin toggle on non-Windows platforms; gate the keybinding/command behind `cfg(windows)` or a runtime `windows` check.
2. Check availability first with `imp::pinned()`-style feature detection (or expose an `is_supported()` returning `cfg!(windows)`) and hide the feature in the UI on unsupported platforms.
3. If pinning is needed on Linux/macOS, implement a platform-specific backend (e.g. via WM hints) instead of relying on this Windows-only module.

Example fix

// before
start_toggle(None)?; // panics/bails on non-Windows
// after
if cfg!(windows) {
    start_toggle(None)?;
}

if !cfg!(windows) { return; // skip pin toggle }

fn pinning_supported() -> bool { cfg!(windows) }

When it happens

Trigger: Calling `imp::start_toggle` (the pin-toggle dispatch) on any non-Windows platform (Linux, macOS), since the `#[cfg(not(windows))]` stub unconditionally returns this error.

Common situations: Running the TUI on Linux or macOS and triggering the window-pin toggle keybinding or command; CI or dev environments on non-Windows hosts exercising the pin feature; a build without the Windows cfg path compiled in.

Understand the failure class

Background: "unsupported platform" / "not supported on this platform" errors: what they mean and how to fix them — this error's family across 47 libraries.

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AI-assisted analysis of Hmbown/CodeWhale@73e0f67d83 (2026-09-22). Data as JSON: /api/errors/db41751e37b9265b. Report an issue: GitHub.

Appendix: source

Thrown at crates/tui/src/tui/window_control.rs:597

            drop(state);
            reader.join().unwrap();
            assert!(observed.is_ok(), "rendering waited for the window worker");
        }

        #[test]
        fn headless_dispatch_rejects_before_resolving_or_changing_a_window() {
            let error = start_toggle(None).unwrap_err();
            assert!(error.to_string().contains("mailbox is unavailable"));
        }
    }
}

#[cfg(not(windows))]
mod imp {
    pub(super) fn start_toggle(
        _completion_tx: Option<tokio::sync::mpsc::Sender<crate::tui::app::DispatchApplyFn>>,
    ) -> anyhow::Result<()> {
        anyhow::bail!("window pinning is only supported on Windows")
    }

    pub(super) fn pinned() -> bool {
        false
    }
}

/// Whether host-window control is available on this platform.
/// Only Windows consoles can be driven from inside the TUI.
pub(crate) fn available() -> bool {
    cfg!(windows)
}

/// Request a window change without blocking input or claiming it has applied.
/// Both entry points share the worker and its observed completion receipt.
pub(crate) fn toggle_pin(app: &mut crate::tui::app::App) {
    if let Err(error) = imp::start_toggle(app.dispatch_completion_tx.clone()) {
        show_result(app, Err(error));

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