diff --git a/vkm/vkm_stub.c b/vkm/vkm_stub.c
index 62557cd..a098a1c 100644
--- a/vkm/vkm_stub.c
+++ b/vkm/vkm_stub.c
@@ -3,7 +3,7 @@
  *
  * Copyright (C) 2026 Nirenjan Krishnan <nirenjan@nirenjan.org>
  *
- * SPDX-LicenseIdentifier: GPL-2.0-only WITH Classpath-exception-2.0
+ * SPDX-License-Identifier: GPL-2.0-only WITH Classpath-exception-2.0
  */
 
 #include <stdlib.h>
@@ -11,36 +11,50 @@
 
 #include "vkm.h"
 
-// Dummy struct
 struct vkm_context {
+    bool started;
+    bool mouse_hi_res_scroll;
+    bool mouse_horizontal_scroll;
 };
 
-#define DUMMY_CTX (vkm_context *)0xDEADBEEF
-
 vkm_result vkm_init(vkm_context **ctx)
 {
-    if (ctx != NULL) {
-        *ctx = DUMMY_CTX;
-        return VKM_SUCCESS;
+    if (ctx == NULL) {
+        return VKM_ERROR_INVALID_PARAM;
     }
 
-    return VKM_ERROR_INVALID_PARAM;
+    *ctx = calloc(1, sizeof(**ctx));
+    if (*ctx == NULL) {
+        return VKM_ERROR_OUT_OF_MEMORY;
+    }
+
+    return VKM_SUCCESS;
 }
 
 void vkm_exit(vkm_context *ctx)
 {
-    (void)ctx;
+    free(ctx);
 }
 
 vkm_result vkm_start(vkm_context *ctx)
 {
-    if (ctx != DUMMY_CTX) {
+    if (ctx == NULL) {
         return VKM_ERROR_INVALID_PARAM;
     }
 
+    ctx->started = true;
     return VKM_SUCCESS;
 }
 
+bool vkm_is_ready(vkm_context *ctx)
+{
+    if (ctx == NULL) {
+        return false;
+    }
+
+    return ctx->started;
+}
+
 bool vkm_platform_supported(void)
 {
     return false;
@@ -59,28 +73,32 @@ vkm_result vkm_set_option(vkm_context *ctx, vkm_option option, ...)
     char *name;
     vkm_result rc;
 
-    if (ctx != DUMMY_CTX) {
+    if (ctx == NULL) {
         return VKM_ERROR_INVALID_PARAM;
     }
 
     va_start(ap, option);
     rc = VKM_SUCCESS;
     switch (option) {
-        case VKM_OPT_HI_RES_SCROLL:
-        case VKM_OPT_HORIZONTAL_SCROLL:
-            // read as int, as bool is promoted to int when passed as a va_arg
-            flag = va_arg(ap, int);
-            (void)flag;
-            break;
+    case VKM_OPT_HI_RES_SCROLL:
+        flag = (bool)va_arg(ap, int);
+        ctx->mouse_hi_res_scroll = flag;
+        break;
 
-        case VKM_OPT_DEVICE_NAME:
-            name = va_arg(ap, char *);
-            (void)name;
-            break;
+    case VKM_OPT_HORIZONTAL_SCROLL:
+        flag = (bool)va_arg(ap, int);
+        ctx->mouse_horizontal_scroll = flag;
+        break;
 
-        default:
-            rc = VKM_ERROR_INVALID_PARAM;
-            break;
+    case VKM_OPT_DEVICE_NAME:
+        name = va_arg(ap, char *);
+        (void)name;
+        rc = VKM_ERROR_NOT_SUPPORTED;
+        break;
+
+    default:
+        rc = VKM_ERROR_INVALID_PARAM;
+        break;
     }
 
     va_end(ap);
@@ -89,18 +107,24 @@ vkm_result vkm_set_option(vkm_context *ctx, vkm_option option, ...)
 
 vkm_result vkm_mouse_move(vkm_context *ctx, int dx, int dy)
 {
-    (void)dx;
-    (void)dy;
-    if (ctx != DUMMY_CTX) {
+    if (ctx == NULL) {
         return VKM_ERROR_INVALID_PARAM;
     }
 
-    return VKM_SUCCESS;
+    if (!vkm_is_ready(ctx)) {
+        return VKM_ERROR_NOT_READY;
+    }
+
+    if (dx == 0 && dy == 0) {
+        return VKM_ERROR_NO_CHANGE;
+    }
+
+    return VKM_ERROR_NOT_SUPPORTED;
 }
 
 vkm_result vkm_mouse_click(vkm_context *ctx, vkm_mouse_button button, vkm_button_state state)
 {
-    if (ctx != DUMMY_CTX) {
+    if (ctx == NULL) {
         return VKM_ERROR_INVALID_PARAM;
     }
 
@@ -112,12 +136,16 @@ vkm_result vkm_mouse_click(vkm_context *ctx, vkm_mouse_button button, vkm_button
         return VKM_ERROR_INVALID_PARAM;
     }
 
-    return VKM_SUCCESS;
+    if (!vkm_is_ready(ctx)) {
+        return VKM_ERROR_NOT_READY;
+    }
+
+    return VKM_ERROR_NOT_SUPPORTED;
 }
 
 vkm_result vkm_mouse_scroll(vkm_context *ctx, vkm_mouse_scroll_direction dir)
 {
-    if (ctx != DUMMY_CTX) {
+    if (ctx == NULL) {
         return VKM_ERROR_INVALID_PARAM;
     }
 
@@ -125,5 +153,28 @@ vkm_result vkm_mouse_scroll(vkm_context *ctx, vkm_mouse_scroll_direction dir)
         return VKM_ERROR_INVALID_PARAM;
     }
 
+    if (!vkm_is_ready(ctx)) {
+        return VKM_ERROR_NOT_READY;
+    }
+
+    if (dir == VKM_MOUSE_SCROLL_LEFT || dir == VKM_MOUSE_SCROLL_RIGHT) {
+        if (!ctx->mouse_horizontal_scroll) {
+            return VKM_ERROR_INVALID_PARAM;
+        }
+    }
+
+    return VKM_ERROR_NOT_SUPPORTED;
+}
+
+vkm_result vkm_sync(vkm_context *ctx)
+{
+    if (ctx == NULL) {
+        return VKM_ERROR_INVALID_PARAM;
+    }
+
+    if (!vkm_is_ready(ctx)) {
+        return VKM_ERROR_NOT_READY;
+    }
+
     return VKM_SUCCESS;
 }