steamify-cachyos/AGENTS.md

AGENTS.md

Guidance for AI coding agents working on this repository. See README.md for what the script does from a user's point of view.

Project overview

A bash wizard that makes CachyOS (KDE Plasma 6 + plasma-login-manager) boot into a SteamOS-style gamescope session, with working switching between gamescope and the Plasma desktop. Primary target: the Valve Steam Machine (DMI Valve/Fremont) running CachyOS Desktop edition.

Layout

• setup-gamescope-boot.sh - the only entry point. Pre-flight checks, sources lib/*.sh, runs the menu and applies the plan. No component logic here.
• lib/*.sh - one file per responsibility, each defining functions only (no top-level side effects besides constants). See the table in README.md.
• Components. Every menu item <id> (listed in COMPONENTS and LABEL in lib/menu.sh) provides <id>_status (return 0 if on, detected from the system, no state file needed), <id>_enable and <id>_disable, all idempotent. <id>_enable is also used to re-apply. Optional <id>_available is checked via component_available (e.g. machine only on Fremont). Turn-on order is COMPONENTS order, turn-off reverse; gaming must stay first. Dependencies live in toggle_component.
• Reversibility. Every per-user KDE setting a component changes goes through kset <component> <file> <group|group> <key> <value> (lib/state.sh), which records the old value once; <id>_disable calls krevert <component>. Never call kwriteconfig6 directly for settings a component owns. System files are backed up with backup_file and restored on disable.

Conventions

• Bash, set -uo pipefail (no -e): check exit codes of steps that matter explicitly (|| { err ...; exit 1; } or || return 1).
• Use the helpers from lib/common.sh (info, ok, warn, err, ask_yn, backup_file) for all output and prompts.
• Runs as the normal user; use sudo per command, never require root. Per-user files go in $HOME of the invoking user (the script refuses to configure another user).
• Idempotent: every step must be safe to re-run without duplicating lines or settings. Back up system files with backup_file before the first edit.
• Don't overwrite package-owned files in /etc/xdg or /usr. KDE settings go into the user's config via kwriteconfig6 (or merge_kde_config for whole Valve ini files).
• Package installs after a user already confirmed use --noconfirm: a second pacman prompt consumes the next scripted answer.
• Comments explain why (the CachyOS/Plasma quirk being worked around), not what the next line does.

Non-obvious behaviour to preserve

• apply_changes sets $LOGIN_MANAGER from the menu: sddm when single user mode is wanted, else plasmalogin. Toggling single user re-applies gaming so it moves to the other login manager. Single user mode hides the launcher's Session dropdown via kickoff primaryActions=3 (restricting action/logout also hides Restart/Shut Down). Two login-manager paths: sddm (like SteamOS: steam-set-session writes /etc/sddm.conf.d/zz-steamos-autologin.conf, which SDDM honours; we add User=/Relogin= in 10-gamescope-autologin.conf, and /etc/sddm.conf must not contain [Autologin] since it's read last) and plasmalogin (needs the sync bridge and the shortcut's sudoers rule). Both must keep working.

• steam-set-session only writes /etc/plasmalogin.conf.d/zz-steamos-autologin.conf; the base /etc/plasmalogin.conf wins, hence the sync bridge. The sync service needs StartLimitIntervalSec=0, or bursts of session switches get it rate-limited and all later switches silently stop working.

• The sync script must only edit Session= inside [Autologin].

• The Steam desktop autostart unit is guarded with ExecCondition=... XDG_CURRENT_DESKTOP = KDE, so it doesn't start a second Steam inside gamescope.

• Vapor theme: install Valve's files as shipped. Don't rewrite Valve's metadata.json; the icon theme is breeze-dark (there is no "Vapor" icon theme); wallpapers are flat JPGs in usr/share/wallpapers. lookandfeeltool does not switch the color scheme, so plasma-apply-colorscheme Vapor is applied explicitly.

• Plasma 6 has no separate systemtray containment: tray settings live on the systemtray applet itself (Valve's setup script targets Plasma 5).

• Restart plasmashell via systemctl --user (plasma-plasmashell.service), not plasmashell --replace from the script's shell: a shell without the session environment yields a light-themed desktop (context menus, apps it launches).

• Live Plasma changes (qdbus6 ... evaluateScript, lookandfeeltool) only run when plasmashell is running; config-file fallbacks cover the rest.

• plasmashell writes its in-memory config back on exit: edit panel/applet/ wallpaper files only between stop_plasmashell_for_edit and restart_plasmashell_if_stopped (lib/common.sh).

• LED driver: leds-valve-dkms-git's Makefile builds against uname -r, so the script builds explicitly for the running kernel and installs headers for every installed kernel first. The module creates /sys/class/leds/valve-leds*.

• Relogin=true means a gamescope that fails to start is relaunched in a tight loop; keep that in mind when changing session handling.

Checking changes

There is no test suite. At minimum:

for f in setup-gamescope-boot.sh lib/*.sh; do bash -n "$f"; done
shellcheck -S warning setup-gamescope-boot.sh lib/*.sh   # if available

Behaviour is verified in a CachyOS QEMU/KVM test VM. The VM scripts and a Claude Code skill describing the whole test workflow (snapshots, SSH, running the wizard with scripted menu input such as printf '2\n\ny\nn\n', the per-component checks, reboot checks, the full test matrix, --fremont to fake Steam Machine hardware) live in cachyos-gamescope-boot-dev-env. Gamescope itself and the real LED bar can only be verified on hardware.