Document remaining neon customizations from shell history; fix zram loose ends

Persist vm.swappiness=100 in /etc/sysctl.d/99-zram.conf and delete the
unused /swapfile. New NEON-CUSTOMIZATIONS.md covers keyd, USB-C DP
modules, HWE-edge kernel, tmpfs /tmp and localepurge, r8152 DKMS
history, tailscale, and third-party repos/tools.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

CLAUDE.md

@@ -153,5 +153,16 @@ the eMMC has no audio yet (not investigated).
 
 Disk swapfile replaced by an 8GiB zstd zram device via `zram-tools`
 (`/etc/default/zramswap`), set up 2026-03-05. Documented in **`ZRAM.md`**.
-Loose ends as of 2026-09-27: `vm.swappiness=100` was only set at runtime
+`vm.swappiness=100` is persisted in `/etc/sysctl.d/99-zram.conf`, and the
-(back to 60), and the unused 512MiB `/swapfile` is still on disk.
+old `/swapfile` was deleted (both 2026-09-27).
+
+## Other neon customizations
+
+See **`NEON-CUSTOMIZATIONS.md`** (reconstructed 2026-09-27 from shell
+history): keyd Chromebook keyboard remap (built from source,
+`/etc/keyd/default.conf`, internal keyboard only), USB-C DisplayPort
+via `/etc/modules-load.d/cros-video.conf` (`cros_ec_typec`,
+`typec_displayport`), `linux-generic-hwe-24.04-edge` (why it's on 7.x
+kernels) plus the 6.17 fallback, `/tmp` on tmpfs + localepurge to spare
+the USB-card root, the removed r8152 DKMS driver, disabled tailscaled,
+and third-party apt repos and hand-installed tools.

NEON-CUSTOMIZATIONS.md

@@ -0,0 +1,154 @@
+# Other neon customizations on hp-chell
+
+Reconstructed on 2026-09-27 from `~matt/.bash_history` (551 lines,
+roughly early March 2026 onward), `/root/.bash_history`, and the live
+system. Topics with their own docs:
+[`AUDIO.md`](AUDIO.md), [`ZRAM.md`](ZRAM.md),
+[`CHROMEOS-FLEX.md`](CHROMEOS-FLEX.md), and the kernel 7.x black-screen
+fix in `CLAUDE.md`.
+
+## Keyboard: keyd remapping for the Chromebook layout
+
+The Chromebook keyboard has no F-keys, Delete, Home/End, PgUp/PgDn or
+Caps Lock; there's a "Search" key where Caps Lock would be. **keyd**
+remaps it at the evdev level, so it works everywhere (console, X,
+Wayland, the login screen).
+
+- Built from source, not from apt (apt has no keyd for noble):
+  `~/github/keyd` (<https://github.com/rvaiya/keyd>, `7c0aecb`,
+  **v2.6.0**), `make && sudo make install`, which puts the binary at
+  `/usr/local/bin/keyd`. Then `sudo systemctl enable --now keyd`. Neither
+  apt nor unattended upgrades will ever update it; rebuild from the
+  checkout to upgrade.
+- Config: `/etc/keyd/default.conf`. Apply edits with `sudo keyd reload`;
+  find key names and device IDs with `sudo keyd monitor`. Summary:
+  - `[ids] 0001:0001`: **only the internal keyboard** (`AT Translated Set
+    2 keyboard`); external USB keyboards are left alone (use `*` to
+    include them).
+  - `leftmeta = overload(meta, leftmeta)`: Search acts as Meta when held
+    and taps as Meta (opens the KDE launcher).
+  - **Search + top row gives F1 to F10** (back, forward, refresh, zoom,
+    scale, brightness down/up, mute, volume down/up). **Search + `-`/`=`
+    gives F11/F12.**
+  - The same top-row to F-key mapping with Alt, Ctrl or Shift held. The
+    `A-`/`C-`/`S-` prefixes re-apply the modifier, which keyd otherwise
+    strips, so e.g. Alt+F4 works as Alt+Search+Zoom.
+  - Search + Backspace = Delete; Search + arrows = Home/End/PgUp/PgDn.
+  - Alt + Backspace = Delete; **Alt + Search = Caps Lock**.
+
+## USB-C DisplayPort output: load the cros_ec Type-C drivers
+
+`/etc/modules-load.d/cros-video.conf` (2026-03-12):
+
+```
+cros_ec_typec
+typec_displayport
+```
+
+These don't autoload on chell, and without them the USB-C ports don't
+negotiate DisplayPort alt mode, so there's no video out over USB-C.
+Both are loaded as of 2026-09-27.
+
+## Kernel: HWE-edge meta package
+
+`linux-generic-hwe-24.04-edge` is installed (alongside the plain
+`linux-generic-hwe-24.04`), and it's why the machine is on 7.x kernels
+(`7.0.0-34` now), not noble's regular HWE line. Also installed
+deliberately as a known-good fallback: `linux-image-generic-6.17` /
+`linux-headers-generic-6.17` (`6.17.0-42`), which is the fallback kernel
+named in the black-screen notes in `CLAUDE.md`. Old 7.x kernels
+(`7.0.0-30`, `7.0.0-14`) are still installed as well.
+
+`/etc/default/grub` (edited by hand several times; both `matt` and root
+history show `nano /etc/default/grub` + `update-grub`): `GRUB_DEFAULT=0`,
+`GRUB_TIMEOUT=5`, `GRUB_TIMEOUT_STYLE=menu`,
+`GRUB_CMDLINE_LINUX_DEFAULT='splash'` (see `setup-i915-kernel7-fix.sh`).
+
+## Storage / wear on the USB-card root
+
+neon's root is an external USB/SD card, so a few changes cut down writes
+and space use:
+- **`/tmp` is tmpfs** (in `/etc/fstab`:
+  `tmpfs /tmp tmpfs defaults,noatime,mode=1777 0 0`). Not in the shell
+  history, so it was probably added in the same `nano /etc/fstab` edit
+  that disabled the swapfile.
+- The swapfile was replaced by zram (see `ZRAM.md`).
+- **`localepurge`** is installed and configured (via `dpkg-reconfigure
+  localepurge`) to keep only `en`, `en_CA.UTF-8`, `en_US.UTF-8` and
+  `fr_CA.UTF-8`, and delete other locales' files on every package
+  install (`USE_DPKG`, `MANDELETE`). If another language's translations
+  or man pages are ever needed, add them with
+  `sudo dpkg-reconfigure localepurge`.
+
+## Networking
+
+- **Realtek USB Ethernet (`enx00e04c68003e`, r8152-family 2.5G
+  adapter):** the out-of-tree driver from
+  <https://github.com/awesometic/realtek-r8152-dkms> (`~/github/realtek-r8152-dkms`)
+  was once installed with DKMS, together with unloading `cdc_ether` /
+  `cdc_ncm` / `cdc_mbim` and testing with `iperf3` against `pet630`,
+  MTU 9000 and `ethtool -K` offloads. It was **later removed**
+  (`sudo ./dkms-remove.sh`), around a kernel upgrade that it probably
+  broke. `dkms status` is empty now, so the adapter gets the in-kernel
+  driver. The MTU and offload tweaks were runtime-only and aren't
+  persisted anywhere.
+- **Tailscale** is installed (repo in `tailscale.list`) but
+  `tailscaled` is **disabled** (`systemctl disable tailscaled`, around
+  the time the agent account was created).
+
+## Firmware and access
+
+- MrChromebox firmware utility run twice
+  (`curl -LOf https://mrchromebox.tech/firmware-util.sh && sudo bash
+  firmware-util.sh`); the second run was the 2026-09-03 update to
+  `MrChromebox-2606.1` (see `CLAUDE.md`).
+- `agent-user` created with
+  `create-agent-user.sh` from
+  `https://gist.ergosteur.com/ergosteur/41df939a435741bfac431ac3d4b888d0`
+  (a copy is in `~matt`).
+
+## Software and third-party apt repos
+
+Not hardware-specific, but needed to rebuild the machine. The
+repositories in `/etc/apt/sources.list.d/` beyond neon's own:
+
+| Source file | What | Set up via |
+|---|---|---|
+| `vscodium.sources` | VSCodium (`codium`) | paulcarroty key into `/usr/share/keyrings/vscodium-archive-keyring.gpg` |
+| `google-chrome.sources` | Google Chrome | installing the `.deb` from Downloads; set as `x-www-browser` / `gnome-www-browser` via `update-alternatives` |
+| `docker.sources` | Docker CE | Docker's official apt instructions; `matt` added to the `docker` group |
+| `ansible-ubuntu-ansible-noble.sources` | `ansible-core` | `ppa:ansible/ansible` |
+| `nodesource.sources` | Node.js 24 | `deb.nodesource.com/setup_24.x`; then `npm i -g @google/gemini-cli` |
+| `tailscale.list` | Tailscale | (disabled, see above) |
+
+Other tools installed by hand:
+- **`bws`** (Bitwarden Secrets Manager CLI) v2.0.0: unzipped into
+  `/opt/bitwarden/bws/`, symlinked to `/usr/local/bin/bws`, with
+  completions in `/opt/bitwarden/bws/completions.bash` sourced from
+  `~/.bashrc`.
+- **GlobalProtect VPN** (`PanGPLinux-6.3.3-c31`, `gp_install.sh`, from
+  `~/Downloads`).
+- `pipx`: `mkdocs` plus the injected `mkdocs-material`.
+- Claude Code (`curl -fsSL https://claude.ai/install.sh | bash`).
+
+Notable apt packages installed on top of neon: `codium ffmpeg yt-dlp
+imagemagick python3-pip python3-venv pipx python3-bs4 build-essential
+ncdu bwm-ng wireshark mpv filezilla rpi-imager ntfs-3g exfatprogs
+exfat-fuse hfsutils hfsprogs samba samba-vfs-modules krdc remmina ssh
+iperf3 netcat-openbsd htop btop git pavucontrol-qt bash-completion
+tesseract-ocr{,-eng,-fra,-kor} inxi lsscsi qrencode localepurge
+zram-tools dkms`.
+
+Git identities: `~/.gitconfig` plus `~/.gitconfig.ergosteur` and
+`~/.gitconfig.tfo`, with SSH key aliases in `~/.ssh`:
+`git_ssh_id_ergosteur` → `id_rsa`, and `git_ssh_id_myip4tfo` →
+`id_ed25519`.
+
+## Dead ends in the history (nothing left installed)
+
+- `~/github/chell_audio` (iofq's chell audio repo) was cloned and
+  `linux-modules-extra` / `snd_soc_skl` poked at, before switching to
+  WeirdTreeThing's scripts (see `AUDIO.md`).
+- `ntfs2btrfs` / `ntfsfix` against a `/dev/sda1` of the time. That was
+  an external data card before this layout, not the current neon
+  install, whose `sda1` is its ESP.

ZRAM.md

@@ -56,22 +56,17 @@ zram-related on the kernel command line.
 4. **Raised `vm.swappiness` to 100**, at runtime only
    (`sudo sysctl vm.swappiness=100`). See the loose ends below.
 
-## Loose ends (as of 2026-09-27)
+## Loose ends (fixed 2026-09-27)
 
-- **`vm.swappiness=100` was never made persistent.** It's back to the
+- **`vm.swappiness=100` hadn't been made persistent**: it had been set
-  default **60** now: no `swappiness` line in `/etc/sysctl.conf`,
+  with `sysctl` at runtime only and was back to the default 60. Now
-  `/etc/sysctl.d/` or `/usr/lib/sysctl.d/`. To keep it (a common choice
+  persisted in `/etc/sysctl.d/99-zram.conf` (`vm.swappiness=100`) and
-  with zram-only swap, since swapping to zram is cheap):
+  applied live. Swapping to zram is cheap, so a high swappiness is the
-  ```
+  usual choice. Not changed: `vm.page-cluster` (still `3`). Some zram
-  echo 'vm.swappiness=100' | sudo tee /etc/sysctl.d/99-zram.conf
+  guides set it to `0`, since zram has no seek cost and readahead just
-  sudo sysctl --system
+  wastes work.
-  ```
+- **The unused `/swapfile`** (512MiB, dated 2026-03-04, fstab line
-  Some zram guides also set `vm.page-cluster=0` (currently `3`), because
+  commented out) was deleted.
-  zram has no seek cost and readahead just wastes work.
-- **`/swapfile` still exists**: 512MiB, `root:root 0600`, dated
-  2026-03-04. It's unused since its fstab line is commented out. Remove
-  it with `sudo rm /swapfile` to get the space back, or keep it as a
-  low-priority fallback.
 
 ## Reapplying on a fresh neon install
 
@@ -86,7 +81,7 @@ EOF
 sudo systemctl enable --now zramswap
 # comment out any /swapfile line in /etc/fstab, then:
 sudo swapoff /swapfile
-# optional: persist swappiness
+# persist swappiness
 echo 'vm.swappiness=100' | sudo tee /etc/sysctl.d/99-zram.conf && sudo sysctl --system
 ```