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  "path": "/link/535/17269248/home-row-app-switcher",
  "publishedAt": "2026-02-03T15:23:00.000Z",
  "site": "https://brett.trpstra.net",
  "tags": [
    "LeaderKey",
    "Keyboard Maestro",
    "home row arrow keys",
    "Import to Karabiner",
    "Subscribe Now",
    "on Mastodon",
    "Bluesky",
    "Twitter",
    "Click here if you'd like to help out.",
    "Mastodon",
    "Bluesky",
    "GitHub",
    "everywhere else"
  ],
  "textContent": "Here’s a new Karabiner-Elements trick that I’ve been using to add home row app switching to my workflow. Tools like LeaderKey are great, but sometimes you just want the App Switcher, and sometimes you just want to be lazy with your fingers.\n\nMy goal was a home-row app switcher that triggered without leaving the home row, and didn’t steal keys for normal typing. The solution is a Karabiner-Elements complex modification that uses **simultaneous** key detection: the layer only activates when `A` and `S` are pressed _together_ within a very short window (basically at the exact same time).\n\n**This modification is designed for theKeyboard Maestro app switcher**, not the macOS default `⌘`+`⇥` switcher. Keyboard Maestro’s switcher uses Shift alone to move backward, whereas the system switcher expects `⇧`+`⌘`+`⇥`; the key outputs below match KM’s behavior, so you’d need to adjust the modification (e.g. have `D` send `⇧`+`⇥`) to use it with the built-in app switcher.\n\n## What it does\n\nHold `A` and `S` at the same time. While both are held, you get a temporary layer:\n\n  * **`D`** → previous app (Shift only; KM uses this for backward)\n  * **`F`** → next app (`⌘`+`⇥`)\n  * **`G`** → quit (`⌘`+`Q`)\n\n\n\nSo you chord `A`+`S`, then tap `F`, it loads the App Switcher, then tap `D` or `F` to move through the apps, or `G` to quit the highlighted app. Release `A` and/or `S` and switch to the highlighted app.\n\nThis works great with my home row arrow keys, allowing easy up/down/left/right navigation through Keyboard Maestro’s grid-based app switcher. Two-handed, but still all home row.\n\n## How it avoids hijacking A and S for regular typing\n\nThe modification never intercepts a lone `A` or `S`. It only triggers when both keys are pressed **simultaneously** , with a 50 ms threshold (`basic.simultaneous_threshold_milliseconds`). When you type normally, you press one key, release it, then press another. Your “a” and “s” key events are separated by hundreds of milliseconds, so Karabiner never sees them as a chord. Only an intentional A+S chord activates the layer. Single-key “a” and “s” pass through unchanged.\n\nUnder the hood, the rule uses Karabiner’s `simultaneous` `from` condition: an array of key codes that must all be pressed together. On that chord it sets a variable (`as_layer`) and injects `left_command` so that the following D/F/G rules (which are gated on `as_layer`) produce the right modifiers. When either A or S is released, `to_after_key_up` clears the variable and the layer drops. So you keep full use of `A` and `S` for typing; only the deliberate two-finger chord turns them into a layer key.\n\n## Import this modification\n\nImport to Karabiner ▼\n\nShow JSON Copy JSON URL\n\n🔒\n\n### Premium Content\n\nAnd More\n\nSubscribe Now I'm a Subscriber\n\nLike or share this post on Mastodon, Bluesky, or Twitter.\n\n* * *\n\nBrettTerpstra.com is supported by readers like you. Click here if you'd like to help out.\n\nFind Brett on Mastodon, Bluesky, GitHub, and everywhere else.",
  "title": "Karabiner Home row app switcher",
  "updatedAt": "2026-02-03T15:23:00.000Z"
}