diff --git a/config/corne.keymap b/config/corne.keymap
index 74177b0..39d97b2 100644
--- a/config/corne.keymap
+++ b/config/corne.keymap
@@ -8,13 +8,17 @@
 #include <dt-bindings/zmk/keys.h>
 #include <dt-bindings/zmk/bt.h>
 #include <dt-bindings/zmk/outputs.h>
+#include "keypos_42keys.h"
 
 // C Macros
-#define C_HM_L(k1, k2, k3, k4) &c_hm LGUI k1  &c_hm LALT k2  &c_hm LCTRL k3  &c_hm LSHIFT k4
-#define C_HM_R(k1, k2, k3, k4) &c_hm RSHIFT k1  &c_hm RCTRL k2  &c_hm RALT k3  &c_hm RGUI k4
+#define C_HM_L(k1, k2, k3, k4) &c_hm_l LGUI k1  &c_hm_l LALT k2  &c_hm_l LCTRL k3  &c_hm_l LSHIFT k4
+#define C_HM_R(k1, k2, k3, k4) &c_hm_r RSHIFT k1  &c_hm_r RCTRL k2  &c_hm_r RALT k3  &c_hm_r RGUI k4
 #define C_LT(l1, k1) &c_lt l1 k1
 #define XXXXXX &none
 #define ______ &trans
+#define KEYS_L LT4 LT3 LT2 LT1 LT0 LM4 LM3 LM2 LM1 LM0 LB4 LB3 LB2 LB1 LB0 // left-hand keys
+#define KEYS_R RT0 RT1 RT2 RT3 RT4 RM0 RM1 RM2 RM3 RM4 RB0 RB1 RB2 RB3 RB4 // right-hand keys
+#define KEYS_T LH2 LH1 LH0 RH0 RH1 RH2 // thumb keys
 
 // Layers
 #define COLEMAK_DH 0
@@ -27,13 +31,28 @@
 / {
     // docs: https://zmk.dev/docs/behaviors/hold-tap
     behaviors {
-        c_hm: homerow_mod {
+        c_hm_l: homerow_mod {
             compatible = "zmk,behavior-hold-tap";
             #binding-cells = <2>;
             quick-tap-ms = <150>;
             tapping-term-ms = <220>;
+            require-prior-idle-ms = <120>; // tap if prev non modifier key was pressed within that time
             flavor = "tap-preferred";
             bindings = <&kp>, <&kp>;
+            hold-trigger-key-positions = <KEYS_R KEYS_T>;
+            hold-trigger-on-release; // delay positional check until key-release
+        };
+
+        c_hm_r: homerow_mod {
+            compatible = "zmk,behavior-hold-tap";
+            #binding-cells = <2>;
+            quick-tap-ms = <150>;
+            tapping-term-ms = <220>;
+            require-prior-idle-ms = <120>; // tap if prev non modifier key was pressed within that time
+            flavor = "tap-preferred";
+            bindings = <&kp>, <&kp>;
+            hold-trigger-key-positions = <KEYS_L KEYS_T>;
+            hold-trigger-on-release; // delay positional check until key-release
         };
 
         c_lt: layer_tab {
@@ -149,4 +168,4 @@
     };
 };
 
-// vim: ft=c 
+// vim: ft=c
diff --git a/config/keypos_42keys.h b/config/keypos_42keys.h
new file mode 100644
index 0000000..f1ec50f
--- /dev/null
+++ b/config/keypos_42keys.h
@@ -0,0 +1,60 @@
+/*                                      42 KEY MATRIX / LAYOUT MAPPING
+
+  ╭────────────────────────┬────────────────────────╮ ╭─────────────────────────┬─────────────────────────╮
+  │  0   1   2   3   4   5 │  6   7   8   9  10  11 │ │ LT5 LT4 LT3 LT2 LT1 LT0 │ RT0 RT1 RT2 RT3 RT4 RT5 │
+  │ 12  13  14  15  16  17 │ 18  19  20  21  22  23 │ │ LM5 LM4 LM3 LM2 LM1 LM0 │ RM0 RM1 RM2 RM3 RM4 RM5 │
+  │ 24  25  26  27  28  29 │ 30  31  32  33  34  35 │ │ LB5 LB4 LB3 LB2 LB1 LB0 │ RB0 RB1 RB2 RB3 RB4 RB5 │
+  ╰───────────╮ 36  37  38 │ 39  40  41 ╭───────────╯ ╰───────────╮ LH2 LH1 LH0 │ RH0 RH1 RH2 ╭───────────╯
+              ╰────────────┴────────────╯                         ╰─────────────┴─────────────╯             */
+
+#pragma once
+
+#define LT0  5  // left-top row
+#define LT1  4
+#define LT2  3
+#define LT3  2
+#define LT4  1
+#define LT5  0
+
+#define RT0  6  // right-top row
+#define RT1  7
+#define RT2  8
+#define RT3  9
+#define RT4 10
+#define RT5 11
+
+#define LM0 17  // left-middle row
+#define LM1 16
+#define LM2 15
+#define LM3 14
+#define LM4 13
+#define LM5 12
+
+#define RM0 18  // right-middle row
+#define RM1 19
+#define RM2 20
+#define RM3 21
+#define RM4 22
+#define RM5 23
+
+#define LB0 29  // left-bottom row
+#define LB1 28
+#define LB2 27
+#define LB3 26
+#define LB4 25
+#define LB5 24
+
+#define RB0 30  // right-bottom row
+#define RB1 31
+#define RB2 32
+#define RB3 33
+#define RB4 34
+#define RB5 35
+
+#define LH0 38  // left thumb keys
+#define LH1 37
+#define LH2 36
+
+#define RH0 39  // right thumb keys
+#define RH1 40
+#define RH2 41