Assisted-by: Claude Opus 5.5 via Claude Code

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+# alpheus
+
+A portable unibody keyboard, defined for [Ergogen][ergogen] in
+`layout.yml`.
+
+[ergogen]: https://ergogen.xyz
+
+## Design considerations
+
+The end goal is a portable, battery-powered, wireless keyboard. The
+design gets there in small steps, so the interim builds are wired and
+run [ZMK][zmk].
+
+[zmk]: https://zmk.dev
+
+The layout keeps the Atreus's design principles, with these changes:
+
+- No number row.
+- Arrows and modifiers on the primary layer.
+- More thumb keys, possibly stacked 1u keys like the current sketch.
+
+The keymap will be a mashup of my [Plankeus][plankeus-keymap] and
+[Kyria][kyria] layouts.
+
+[plankeus-keymap]: https://github.com/kejadlen/qmk_firmware/tree/main/keyboards/atreus/keymaps/kejadlen
+[kyria]: https://git.kejadlen.dev/alpha/qmk_userspace/src/branch/main/keyboards/splitkb/kyria/keymaps/kejadlen
+
+These are still undecided:
+
+- Power from AAA batteries, which are easy to replace on the go, or
+  from a battery pack that recharges over a cable.
+- A TrackPoint-style pointing stick, if there's room for one.
+- Kailh PG1316S ultra-low-profile switches, like the mikefive uses.
+
+## Lineage
+
+- The [Atreus][atreus], by Phil Hagelberg, is a compact split keyboard
+  whose halves are rotated toward each other.
+- The [Planck][planck], from OLKB, is a 40% ortholinear keyboard.
+- Plankeus is my own earlier design, combining concepts from the
+  Planck and the Atreus. Its OpenSCAD case is in `plankeus.scad`, and
+  the first version of `layout.yml` was a port of it. The [build
+  log][plankeus] is on Reddit.
+
+[atreus]: https://github.com/technomancy/atreus
+[planck]: https://olkb.com/collections/planck
+[plankeus]: https://old.reddit.com/r/MechanicalKeyboards/comments/2tn3zb/my_atreusplanck_build_log/
+
+## Inspiration
+
+- The [mikefive][mikefive], by mikeholscher, is a wireless keyboard
+  only 5 mm thick, built around ultra-low-profile Kailh PG1316S
+  switches.
+
+[mikefive]: https://github.com/mikeholscher/zmk-config-mikefive