diff --git a/keymaps/custom/keymap.c b/keymaps/custom/keymap.c
index 1e83406..90b7a15 100644
--- a/keymaps/custom/keymap.c
+++ b/keymaps/custom/keymap.c
@@ -1,10 +1,10 @@
 #include QMK_KEYBOARD_H
 #include "keymap_introspection.h"
 #include "dynamic_keymap.h"
-#include "mac_mode.h"
+#include "os_mode.h"
 
 enum custom_keycodes {
-    CK_MCMD = SAFE_RANGE, // toggle mac-command mode
+    CK_OSMODE = SAFE_RANGE, // cycle OS mode
 };
 
 typedef struct {
@@ -121,7 +121,7 @@ ________________________________________________________________________________
 */
 
   [1] = LAYOUT(
-    QK_BOOT,   KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, CK_MCMD,     KC_MPLY,
+    QK_BOOT,   KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, CK_OSMODE, KC_MPLY,
     KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, RGB_TOG, RGB_VAD, RGB_VAI, KC_TRNS,     KC_VOLU,
         KC_PSCR, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_HOME, KC_PGDN, KC_PGUP, KC_END,  KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_VOLD,
           KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_LEFT, KC_DOWN, KC_UP,   KC_RGHT, KC_TRNS, KC_TRNS,    KC_TRNS,     KC_MUTE,
@@ -130,7 +130,7 @@ ________________________________________________________________________________
   ),
 
   [2] = LAYOUT(
-    KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,     KC_TRNS,
+    KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,   KC_TRNS,
     KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,     KC_TRNS,
         KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,
           KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,    KC_TRNS,     KC_TRNS,
@@ -139,7 +139,7 @@ ________________________________________________________________________________
   ),
 
   [3] = LAYOUT(
-    KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,     KC_TRNS,
+    KC_TRNS,   KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,   KC_TRNS,
     KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,     KC_TRNS,
         KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,
           KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS, KC_TRNS,    KC_TRNS,     KC_TRNS,
@@ -148,62 +148,65 @@ ________________________________________________________________________________
   ),
 };
 
-// Override layer resolution: in mac mode, any modifier forces layer 0 (ignores FN)
+// Override layer resolution: any modifier forces layer 0 (ignores FN)
 uint16_t keymap_key_to_keycode(uint8_t layer, keypos_t key) {
-    if (mac_mode && (get_mods() & (MOD_MASK_CTRL | MOD_MASK_SHIFT | MOD_MASK_ALT | MOD_MASK_GUI))) {
+    if (os_mode != OS_MODE_NONE && get_mods()) {
         layer = 0;
     }
-    if (key.row < MATRIX_ROWS && key.col < MATRIX_COLS) {
-        return keycode_at_keymap_location(layer, key.row, key.col);
-    }
-    return KC_NO;
+    return keycode_at_keymap_location(layer, key.row, key.col);
 }
 
-static bool gui_tapped = false;
+static bool super_tapped = false;
 
 bool process_record_user(uint16_t keycode, keyrecord_t *record) {
+    // Cycle OS mode (FN+Del)
+    if (keycode == CK_OSMODE) {
+        if (record->event.pressed) {
+            os_mode = (os_mode + 1) % 4;
+            os_mode_manual = true;
+            rgb_matrix_mode_noeeprom(RGB_MATRIX_SOLID_COLOR);
+            switch (os_mode) {
+                case OS_MODE_NONE:    rgb_matrix_sethsv_noeeprom(HSV_RED);    break;
+                case OS_MODE_LINUX:   rgb_matrix_sethsv_noeeprom(HSV_GREEN);  break;
+                case OS_MODE_MAC:     rgb_matrix_sethsv_noeeprom(HSV_YELLOW); break;
+                case OS_MODE_WINDOWS: rgb_matrix_sethsv_noeeprom(HSV_BLUE);   break;
+            }
+        }
+        return false;
+    }
+
+    // No rewrites in none mode
+    if (os_mode == OS_MODE_NONE) return true;
+
     // Any other key pressed while GUI held means it's being used as a modifier
     if (record->event.pressed && keycode != KC_LGUI) {
-        gui_tapped = false;
+        super_tapped = false;
     }
 
     switch (keycode) {
         // Mac mode: tap Super -> Cmd+Space (Spotlight)
-        // Linux: tap Super passes through normally (KDE app menu)
+        // Linux/Windows: tap Super passes through normally (KDE app menu)
         case KC_LGUI:
-            if (mac_mode) {
+            if (os_mode == OS_MODE_MAC) {
                 if (record->event.pressed) {
-                    gui_tapped = true;
+                    super_tapped = true;
                     register_mods(MOD_BIT(KC_LGUI));
                 } else {
-                    if (gui_tapped) {
+                    if (super_tapped) {
                         tap_code(KC_SPC); // GUI still held, sends Super+Space
-                        gui_tapped = false;
+                        super_tapped = false;
                     }
                     unregister_mods(MOD_BIT(KC_LGUI));
                 }
                 return false;
             }
             break;
-        case CK_MCMD:
-            if (record->event.pressed) {
-                mac_mode = !mac_mode;
-                mac_mode_manual = true;
-                // Flash LEDs to indicate mode: green = mac, red = normal
-                rgb_matrix_mode_noeeprom(RGB_MATRIX_SOLID_COLOR);
-                if (mac_mode) {
-                    rgb_matrix_sethsv_noeeprom(HSV_GREEN);
-                } else {
-                    rgb_matrix_sethsv_noeeprom(HSV_BLUE);
-                }
-            }
-            return false;
         // Mac mode rewrites:
         //   Ctrl+C/V       -> Super+C/V   (copy/paste)
         //   Ctrl+Shift+C/V -> Super+C/V   (terminal copy/paste)
         case KC_C:
         case KC_V:
-            if (mac_mode && record->event.pressed) {
+            if (os_mode == OS_MODE_MAC && record->event.pressed) {
                 if (rewrite_mods(keycode, CTRL_TO_SUPER)) return false;
                 if (rewrite_mods(keycode, CTRL_SHIFT_TO_SUPER)) return false;
             }
@@ -218,7 +221,7 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
         case KC_W:
         case KC_L:
         case KC_R:
-            if (mac_mode && record->event.pressed) {
+            if (os_mode == OS_MODE_MAC && record->event.pressed) {
                 if (rewrite_mods(keycode, CTRL_TO_SUPER)) return false;
             }
             break;
@@ -228,7 +231,7 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
         case KC_Z:
         case KC_T:
         case KC_N:
-            if (mac_mode && record->event.pressed) {
+            if (os_mode == OS_MODE_MAC && record->event.pressed) {
                 if (rewrite_mods(keycode, CTRL_TO_SUPER)) return false;
                 if (rewrite_mods(keycode, CTRL_SHIFT_TO_CMD_SHIFT)) return false;
             }
@@ -238,7 +241,7 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
         //   Ctrl+Left/Right -> Alt+Left/Right         (word navigation)
         case KC_LEFT:
         case KC_RGHT:
-            if (mac_mode && record->event.pressed) {
+            if (os_mode == OS_MODE_MAC && record->event.pressed) {
                 if (rewrite_mods(keycode, CTRL_ALT_TO_CTRL)) return false;
                 if (rewrite_mods(keycode, CTRL_TO_ALT)) return false;
             }
@@ -246,7 +249,7 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
         // Mac mode rewrites:
         //   Ctrl+Backspace -> Alt+Backspace   (delete word backward)
         case KC_BSPC:
-            if (mac_mode && record->event.pressed) {
+            if (os_mode == OS_MODE_MAC && record->event.pressed) {
                 if (rewrite_mods(keycode, CTRL_TO_ALT)) return false;
             }
             break;
@@ -254,38 +257,41 @@ bool process_record_user(uint16_t keycode, keyrecord_t *record) {
         //   Home -> Super+Left    (line start)
         //   End  -> Super+Right   (line end)
         case KC_HOME:
-            if (mac_mode && record->event.pressed) {
+            if (os_mode == OS_MODE_MAC && record->event.pressed) {
                 if (rewrite_mods_and_key(NONE_TO_SUPER, KC_LEFT)) return false;
             }
             break;
         case KC_END:
-            if (mac_mode && record->event.pressed) {
+            if (os_mode == OS_MODE_MAC && record->event.pressed) {
                 if (rewrite_mods_and_key(NONE_TO_SUPER, KC_RGHT)) return false;
             }
             break;
         // Mac mode rewrites:
         //   Alt+F4  -> Super+Q   (quit app)
         case KC_F4:
-            if (mac_mode && record->event.pressed) {
+            if (os_mode == OS_MODE_MAC && record->event.pressed) {
                 if (rewrite_mods_and_key(ALT_TO_SUPER, KC_Q)) return false;
             }
             break;
         // Mac mode rewrites:
         //   Alt+Tab -> Super+Tab   (app switcher)
         case KC_TAB:
-            if (mac_mode && record->event.pressed) {
+            if (os_mode == OS_MODE_MAC && record->event.pressed) {
                 if (rewrite_mods(keycode, ALT_TO_SUPER)) return false;
             }
             break;
-        // Workspace overview (both modes):
-        //   Super+Up -> Super+W   (KDE overview, linux)
-        //   Super+Up -> Ctrl+Up   (Mission Control, mac)
+        // Workspace overview:
+        //   Super+Up -> Super+W     (KDE overview, linux)
+        //   Super+Up -> Ctrl+Up     (Mission Control, mac)
+        //   Super+Up -> Super+Tab   (Task View, windows)
         case KC_UP:
             if (record->event.pressed) {
-                if (mac_mode) {
+                if (os_mode == OS_MODE_MAC) {
                     if (rewrite_mods(keycode, SUPER_TO_CTRL)) return false;
-                } else {
+                } else if (os_mode == OS_MODE_LINUX) {
                     if (rewrite_mods_and_key(SUPER_TO_SUPER, KC_W)) return false;
+                } else if (os_mode == OS_MODE_WINDOWS) {
+                    if (rewrite_mods_and_key(SUPER_TO_SUPER, KC_TAB)) return false;
                 }
             }
             break;
diff --git a/keymaps/custom/mac_mode.h b/keymaps/custom/mac_mode.h
deleted file mode 100644
index 148d337..0000000
--- a/keymaps/custom/mac_mode.h
+++ /dev/null
@@ -1,6 +0,0 @@
-#pragma once
-
-#include <stdbool.h>
-
-extern bool mac_mode;
-extern bool mac_mode_manual;
diff --git a/keymaps/custom/os_detect.c b/keymaps/custom/os_detect.c
index d736d93..b828701 100644
--- a/keymaps/custom/os_detect.c
+++ b/keymaps/custom/os_detect.c
@@ -2,28 +2,48 @@
 #include "timer.h"
 #include "rgb_matrix.h"
 
-#include "mac_mode.h"
+#include "os_mode.h"
 
-bool mac_mode = false;
-bool mac_mode_manual = false;
+os_mode_t os_mode = OS_MODE_NONE;
+bool os_mode_manual = false;
 static bool os_detected = false;
 static uint32_t flash_start = 0;
 
+static void flash_mode_color(void) {
+    rgb_matrix_mode_noeeprom(RGB_MATRIX_SOLID_COLOR);
+    switch (os_mode) {
+        case OS_MODE_NONE:    rgb_matrix_sethsv_noeeprom(HSV_RED);    break;
+        case OS_MODE_LINUX:   rgb_matrix_sethsv_noeeprom(HSV_GREEN);  break;
+        case OS_MODE_MAC:     rgb_matrix_sethsv_noeeprom(HSV_YELLOW); break;
+        case OS_MODE_WINDOWS: rgb_matrix_sethsv_noeeprom(HSV_BLUE);   break;
+    }
+    flash_start = timer_read32();
+}
+
 // Poll OS detection after USB enumeration settles (~2s)
 // Flash indicator color for 500ms then restore default animation
 void matrix_scan_user(void) {
-    if (!os_detected && !mac_mode_manual && timer_elapsed32(0) > 2000) {
+    if (!os_detected && !os_mode_manual && timer_elapsed32(0) > 2000) {
         os_detected = true;
         os_variant_t os = detected_host_os();
-        mac_mode = (os == OS_MACOS || os == OS_IOS);
-        rgb_matrix_mode_noeeprom(RGB_MATRIX_SOLID_COLOR);
-        if (mac_mode) {
-            rgb_matrix_sethsv_noeeprom(HSV_GREEN);
-        } else {
-            rgb_matrix_sethsv_noeeprom(HSV_BLUE);
+        switch (os) {
+            case OS_MACOS:
+            case OS_IOS:
+                os_mode = OS_MODE_MAC;
+                break;
+            case OS_LINUX:
+                os_mode = OS_MODE_LINUX;
+                break;
+            case OS_WINDOWS:
+                os_mode = OS_MODE_WINDOWS;
+                break;
+            default:
+                os_mode = OS_MODE_NONE;
+                break;
         }
-        flash_start = timer_read32();
+        flash_mode_color();
     }
+    // Restore default RGB animation after 500ms indicator flash
     if (flash_start && timer_elapsed32(flash_start) > 500) {
         flash_start = 0;
         rgb_matrix_reload_from_eeprom();
diff --git a/keymaps/custom/os_mode.h b/keymaps/custom/os_mode.h
new file mode 100644
index 0000000..3de621e
--- /dev/null
+++ b/keymaps/custom/os_mode.h
@@ -0,0 +1,18 @@
+#pragma once
+
+#include <stdbool.h>
+
+// Active OS mode, determines which shortcut rewrites are applied.
+// Set automatically by OS detection or manually via FN+Del cycle.
+typedef enum {
+    OS_MODE_NONE,    // no shortcut rewrites
+    OS_MODE_LINUX,   // linux-specific rewrites (e.g. Super+Up -> Super+W)
+    OS_MODE_MAC,     // Ctrl->Super rewrites, Spotlight tap, etc.
+    OS_MODE_WINDOWS, // reserved, currently same as none
+} os_mode_t;
+
+// Current mode, defined in os_detect.c
+extern os_mode_t os_mode;
+
+// True once user manually cycles mode via FN+Del, prevents OS detection override
+extern bool os_mode_manual;