style: use east const in the C API header

Convert the remaining west-const declarations in xone_api.h to east
const so the whole file matches the controller functions added later.
Update the AGENTS.md C bridge section: east const applies to the C
header too; only trailing returns are exempt.

Co-Authored-By: qwen3.8-27b@q3_k_xl: converted C API header to east const

AGENTS.md

@@ -133,8 +133,8 @@ the custom scripts instead of system-installed packages.
 
 - Pure C only: no C++ syntax. The header is imported into Swift via
   `-import-objc-header`, so it must compile as C.
-- Standard C declaration style; trailing returns and east const do not
-  apply here.
+- Standard C declaration style with east const (e.g. `char const*`);
+  trailing returns do not apply here.
 - Use `stdbool.h` types so Swift sees `Bool`.
 
 ## Shell Scripts

CMakeLists.txt

@@ -6,7 +6,7 @@ if(NOT CMAKE_GENERATOR MATCHES "^(Ninja|Xcode)$")
 endif()
 
 cmake_minimum_required(VERSION 3.21)
-project(xone_macos VERSION 0.1.18 LANGUAGES CXX Swift)
+project(xone_macos VERSION 0.1.19 LANGUAGES CXX Swift)
 
 set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 

include/app/xone_api.h

@@ -15,7 +15,7 @@ extern "C" {
 #endif
 
 // Human-readable version string of the protocol stack.
-const char *xone_version(void);
+char const *xone_version(void);
 
 // TRUE if an Xbox Wireless Dongle is connected, FALSE otherwise.
 bool xone_dongle_present(void);
@@ -41,29 +41,29 @@ xone_dongle *xone_open(void);
 // returns 0 once started, -1 if the session is busy or already ready. If
 // firmware_path is NULL, the common upstream image
 // (firmware/xow_dongle.bin) is used.
-int xone_start(xone_dongle *d, const char *firmware_path);
+int xone_start(xone_dongle *d, char const *firmware_path);
 
 // Close the session and release the dongle. Waits for any in-progress start.
 void xone_close(xone_dongle *d);
 
 // Current session state (XONE_STATE_*).
-int xone_state(const xone_dongle *d);
+int xone_state(xone_dongle const *d);
 
 // Human-readable error from the last failed operation. Empty string if none.
-const char *xone_error(const xone_dongle *d);
+char const *xone_error(xone_dongle const *d);
 
 // Product ID of the connected dongle (e.g. 0x02E6).
-uint16_t xone_pid(const xone_dongle *d);
+uint16_t xone_pid(xone_dongle const *d);
 
 // Chip ID from EFUSE (e.g. 0x7612 for MT7612). 0 if unknown.
-uint16_t xone_chip_id(const xone_dongle *d);
+uint16_t xone_chip_id(xone_dongle const *d);
 
 // MAC address from EFUSE as "xx:xx:xx:xx:xx:xx". Valid until xone_close().
-const char *xone_mac_address(const xone_dongle *d);
+char const *xone_mac_address(xone_dongle const *d);
 
 // Build string of the loaded firmware image (e.g. "201703281033____").
 // Empty string if the firmware was not loaded. Valid until xone_close().
-const char *xone_firmware_build(const xone_dongle *d);
+char const *xone_firmware_build(xone_dongle const *d);
 
 // Number of connected controllers.
 int xone_controller_count(xone_dongle const *d);