Address comments

crates/board/src/usb.rs

@@ -17,8 +17,7 @@
 #[cfg(feature = "api-usb-serial")]
 pub mod serial;
 
-// TODO: Should this also be gated behind api-usb-serial feature or should it be
-// a different one?
+#[cfg(feature = "api-usb-ctap")]
 pub mod ctap;
 
 /// USB event.

crates/board/src/usb/ctap.rs

@@ -43,12 +43,12 @@ pub trait Api: Send {
     /// Reads from the USB serial into a buffer.
     ///
     /// Returns the number of bytes read. It could be zero if there's nothing to read.
-    fn read(output: &mut [u8]) -> Result<usize, Error>;
+    fn read(output: &mut [u8; 64]) -> Result<usize, Error>;
 
     /// Writes from a buffer to the USB serial.
     ///
     /// Returns the number of bytes written. It could be zero if the other side is not ready.
-    fn write(input: &[u8]) -> Result<usize, Error>;
+    fn write(input: &[u8; 64]) -> Result<usize, Error>;
 }
 
 pub trait HasCtapHid: Send {
@@ -60,7 +60,7 @@ pub trait HasCtapHid: Send {
 /// Wrapper type for boards using the `usbd_ctaphid` crate.
 pub struct WithCtapHid<T: HasCtapHid> {
     _never: !,
-    _has_serial: T,
+    _has_ctap: T,
 }
 
 /// Helper struct for boards using the `usbd_ctaphid` crate.

crates/prelude/Cargo.toml

@@ -61,6 +61,7 @@ api-store = ["internal-api-store", "wasefire-applet-api/api-store"]
 api-store-fragment = ["internal-api-store", "wasefire-applet-api/api-store-fragment"]
 api-timer = ["wasefire-applet-api/api-timer"]
 api-uart = ["internal-serial", "wasefire-applet-api/api-uart"]
+api-usb-ctap = ["internal-api-usb", "internal-serial", "wasefire-applet-api/api-usb-ctap"]
 api-usb-serial = ["internal-api-usb", "internal-serial", "wasefire-applet-api/api-usb-serial"]
 # Enables all API features.
 full-api = [