Add audax_osx Planck keymap for macOS software neo2

Modern rewrite of the old planck/keymaps/audax (which used the removed fn_actions/action_get_macro API) as the Planck counterpart of the ergodox audax_osx layout. The base layer and Mod3 send positional NE_* scancodes that the OS neo2 layout translates; numbers, function keys and the cursor block stay on firmware layers (_RS/_LW) so they auto-repeat. Mod3 is held on '#', the right Mod3 key taps the neo2 sharp-s, and '@' is Mod3 + y. Built and verified for planck/rev4.

keyboards/planck/keymaps/audax_osx/config.h

@@ -0,0 +1,5 @@
+#pragma once
+
+// Tap/hold window for RSFT_T(KC_ESC) and the right Mod3 tap-for-y key.
+#undef TAPPING_TERM
+#define TAPPING_TERM 200

keyboards/planck/keymaps/audax_osx/keymap.c

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+#include QMK_KEYBOARD_H
+#include "keymap_extras/keymap_neo2.h"
+
+/*
+ * audax_osx (Planck) - neo2 for macOS via the *software* neo2 keyboard layout.
+ *
+ * Planck counterpart of the ergodox `audax_osx` layout, and a modernised
+ * rewrite of the old `planck/keymaps/audax` (which used the long-removed
+ * fn_actions / action_get_macro API and no longer builds).
+ *
+ * The base layer and Mod3 send positional NE_* scancodes; the OS neo2 layout
+ * (neo2-layout-osx .keylayout) produces the characters. Numbers, function keys
+ * and the cursor block live on firmware layers (_RS / _LW) with real keycodes,
+ * so they auto-repeat. See layouts/community/ergodox/audax_osx/readme.md for
+ * the macOS / Karabiner setup.
+ *
+ * Mod3 (layer 3, symbols) is held on the '#' key (NE_L3R / KC_NUHS) on both
+ * Mod3 positions - macOS intercepts CapsLock, so the canonical neo2 Mod3-left
+ * (NE_L3L) is not used. The right Mod3 key taps to ss (neo2 sharp-s); '@' is
+ * Mod3 + y.
+ */
+
+enum planck_layers {
+  _NE,  // neo2 base (positional scancodes)
+  _RS,  // raise: numbers, function and media keys
+  _LW   // lower: cursor block, numbers, ss and shortcuts
+};
+
+enum custom_keycodes {
+  NEO_L3R_SS = SAFE_RANGE, // right Mod3: hold = Mod3 ('#'), tap = ss (sharp-s)
+  NEO_AT                    // @  (neo2 Mod3 + y)
+};
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+
+/* _NE: neo2 base
+ * ,-----------------------------------------------------------------------------------.
+ * | Tab  |   X  |   V  |   L  |   C  |   W  |   K  |   H  |   G  |   F  |   Q  |   Y   |
+ * |------+------+------+------+------+------+------+------+------+------+------+-------|
+ * | Mod3 |   U  |   I  |   A  |   E  |   O  |   S  |   N  |   R  |   T  |   D  |Mod3/ß |
+ * |------+------+------+------+------+------+------+------+------+------+------+-------|
+ * | Shift|   Ü  |   Ö  |   Ä  |   P  |   Z  |   B  |   M  |   ,  |   .  |   J  |Sft/Esc|
+ * |------+------+------+------+------+------+------+------+------+------+------+-------|
+ * | GUI  | Alt  | PgUp | PgDn |Lower | Space| Enter| Ctrl | Alt  | Del  | Bksp |Raise |
+ * `-----------------------------------------------------------------------------------'
+ */
+[_NE] = LAYOUT_planck_grid(
+    KC_TAB,  NE_X,    NE_V,    NE_L,    NE_C,    NE_W,    NE_K,    NE_H,    NE_G,    NE_F,    NE_Q,    NE_Y,
+    NE_L3R,  NE_U,    NE_I,    NE_A,    NE_E,    NE_O,    NE_S,    NE_N,    NE_R,    NE_T,    NE_D,    NEO_L3R_SS,
+    KC_LSFT, NE_UDIA, NE_ODIA, NE_ADIA, NE_P,    NE_Z,    NE_B,    NE_M,    NE_COMM, NE_DOT,  NE_J,    RSFT_T(KC_ESC),
+    KC_LGUI, KC_LALT, KC_PGUP, KC_PGDN, MO(_LW), KC_SPC,  KC_ENT,  KC_LCTL, KC_LALT, KC_DEL,  KC_BSPC, MO(_RS)
+),
+
+/* _RS: raise - numbers, function keys, media
+ * ,-----------------------------------------------------------------------------------.
+ * |   ^  |   1  |   2  |   3  |   4  |   5  |   6  |   7  |   8  |   9  |   0  |       |
+ * |------+------+------+------+------+------+------+------+------+------+------+-------|
+ * |      |  F1  |  F2  |  F3  |  F4  |  F5  |  F6  |      |      |      |      |       |
+ * |------+------+------+------+------+------+------+------+------+------+------+-------|
+ * |      |  F7  |  F8  |  F9  |  F10 |  F11 |  F12 | ->NE | Next | Prev | Boot |       |
+ * |------+------+------+------+------+------+------+------+------+------+------+-------|
+ * |      |      |      |      |      |             |      | Play | Vol- | Vol+ |       |
+ * `-----------------------------------------------------------------------------------'
+ */
+[_RS] = LAYOUT_planck_grid(
+    KC_GRV,  KC_1,    KC_2,    KC_3,    KC_4,    KC_5,    KC_6,    KC_7,    KC_8,    KC_9,    KC_0,    _______,
+    _______, KC_F1,   KC_F2,   KC_F3,   KC_F4,   KC_F5,   KC_F6,   _______, _______, _______, _______, _______,
+    _______, KC_F7,   KC_F8,   KC_F9,   KC_F10,  KC_F11,  KC_F12,  DF(_NE), KC_MNXT, KC_MPRV, QK_BOOT, _______,
+    _______, _______, _______, _______, _______, _______, _______, _______, KC_MPLY, KC_VOLD, KC_VOLU, _______
+),
+
+/* _LW: lower - cursor block (left), numbers (right), ss, shortcuts
+ * ,-----------------------------------------------------------------------------------.
+ * |      | PgUp | Del  |  Up  | Bksp | PgDn |   0  |   1  |   2  |   3  |  ß   |   @   |
+ * |------+------+------+------+------+------+------+------+------+------+------+-------|
+ * |      | Home | Left | Down | Right| End  |   ^  |   4  |   5  |   6  |A(Tab)|      |
+ * |------+------+------+------+------+------+------+------+------+------+------+-------|
+ * |      |      |      |      |      | PgDn |      |   7  |   8  |   9  |G(S(Q))|     |
+ * |------+------+------+------+------+------+------+------+------+------+------+-------|
+ * |      |      |      |      |      |             |      |      |      |      |S(Ins) |
+ * `-----------------------------------------------------------------------------------'
+ */
+[_LW] = LAYOUT_planck_grid(
+    _______, KC_PGUP, KC_DEL,  KC_UP,   KC_BSPC, KC_PGDN, KC_0,    KC_1,    KC_2,    KC_3,    NE_SS,        NEO_AT,
+    _______, KC_HOME, KC_LEFT, KC_DOWN, KC_RGHT, KC_END,  KC_GRV,  KC_4,    KC_5,    KC_6,    LALT(KC_TAB), _______,
+    _______, _______, _______, _______, _______, KC_PGDN, _______, KC_7,    KC_8,    KC_9,    LGUI(S(NE_Q)), _______,
+    _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______,      S(KC_INS)
+)
+
+};
+
+// Tap/hold state for the right Mod3 key (tap = ss, hold = Mod3 / '#').
+static bool l3r_held = false;
+static bool l3r_used = false;
+
+bool process_record_user(uint16_t keycode, keyrecord_t *record) {
+  switch (keycode) {
+    case NEO_L3R_SS:
+      if (record->event.pressed) {
+        register_code(NE_L3R);   // '#' -> neo2 Mod3 while held
+        l3r_held = true;
+        l3r_used = false;
+      } else {
+        unregister_code(NE_L3R);
+        l3r_held = false;
+        if (!l3r_used) {
+          tap_code(NE_SS);       // pure tap -> ss (neo2 sharp-s)
+        }
+      }
+      return false;
+    case NEO_AT:
+      // @ = neo2 Mod3 ('#') + y, held together so it repeats while pressed.
+      if (record->event.pressed) {
+        register_code(NE_L3R);
+        register_code(NE_Y);
+      } else {
+        unregister_code(NE_Y);
+        unregister_code(NE_L3R);
+      }
+      return false;
+    default:
+      // A separate key pressed while Mod3 is held means it is being used as a
+      // modifier, so the release must not emit the tap ('y').
+      if (record->event.pressed && l3r_held) {
+        l3r_used = true;
+      }
+      break;
+  }
+  return true;
+}

keyboards/planck/keymaps/audax_osx/readme.md

@@ -0,0 +1,46 @@
+# audax_osx (Planck) - neo2 for macOS via the software neo2 layout
+
+Planck counterpart of the ergodox `audax_osx` layout, and a modern rewrite of
+the old `planck/keymaps/audax` (which used the long-removed `fn_actions` /
+`action_get_macro` API and no longer builds).
+
+Like the ergodox layout, it expects the **software neo2 keyboard layout** to be
+installed on the Mac (see the full setup in
+`layouts/community/ergodox/audax_osx/readme.md`):
+
+- Install [neo2-layout-osx](https://github.com/jgosmann/neo2-layout-osx) and
+  select it as the active input source.
+- The base layer and Mod3 send positional `NE_*` scancodes; the OS neo2 layout
+  produces the characters.
+
+## Layers
+
+- **`_NE`** - neo2 base. Left/right Mod3 keys both hold `#` (`NE_L3R` /
+  `KC_NUHS`); macOS intercepts CapsLock, so the canonical Mod3-left (`NE_L3L`)
+  is not used. The right Mod3 key **taps to `ß`**; `@` (on `_LW`) is Mod3 + y.
+- **`_RS`** (hold bottom-right) - number row, F-keys, media, `QK_BOOT`, and
+  `DF(_NE)` to reset the default layer.
+- **`_LW`** (hold bottom-left) - cursor block on the left, numbers on the right,
+  `ß`, `@`, and a few macOS shortcuts. These are firmware keycodes, so the
+  cursor keys and numbers auto-repeat when held.
+
+## Building and flashing
+
+Built for a Massdrop/OLKB Planck **rev4** (atmega32u4, mini-USB, USB device
+version 0.0.4, `atmel-dfu` bootloader):
+
+```
+qmk flash -kb planck/rev4 -km audax_osx
+```
+
+Put the board in the bootloader when prompted (physical RESET button on the
+PCB; after this layout is flashed, `QK_BOOT` also lives on the `_RS` layer). The
+keymap is revision-independent - substitute another target (`rev5`, `rev6`,
+`rev6_drop`, ...) if you use a different Planck.
+
+## Notes
+
+- The right Mod3 tap emits `ß` (matching the ergodox `audax_osx`). The original
+  Planck `audax` tapped `y` here; `ß` was chosen instead since `y` already sits
+  on the base layer's top-right.
+- The old `keyboards/planck/keymaps/audax` is left untouched.

keyboards/planck/keymaps/audax_osx/rules.mk

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+BOOTMAGIC_ENABLE = no