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gnu-plus-dotfiles/dot_config/sway/start-swayidle.sh
rain 05e75bc41e sway: extract start-swayidle.sh as single source of truth (fix caffeine)
caffeine.sh click was silently breaking idle lock. Two bugs that
compounded:

1. caffeine.sh inlined its own swayidle command (with swaylock -f -i
   , not lock-fancy.sh), drifted out of sync with sway/config
   which used lock-fancy.sh. Toggle off would restart swayidle with a
   different lock command than the rest of the session.

2. WAYLAND_DISPLAY isn't set in waybar's on-click context. When
   caffeine.sh called 'swaymsg output * power off' (part of the
   restart command) and later called swaylock / grim (via lock-fancy),
   those failed silently. swayidle itself can run without
   WAYLAND_DISPLAY but it can't actually monitor input/output, so it
   exits immediately. Result: user clicks caffeine off, flag clears,
   icon goes back to 'inactive', but auto-lock is silently dead.
   The user thinks they turned caffeine off. They didn't. They're
   just unprotected.

Fix:
- new start-swayidle.sh holds the canonical swayidle command
- sway/config: exec $HOME/.config/sway/start-swayidle.sh
- caffeine.sh: killall swayidle; start-swayidle.sh &
- start-swayidle.sh probes /proc/*/environ for a Wayland client's
  env (mako always has it) and exports WAYLAND_DISPLAY /
  DBUS_SESSION_BUS_ADDRESS / XDG_RUNTIME_DIR / DISPLAY if missing
  before exec'ing swayidle

Single source of truth + env restoration = click works on every box
that has the same Wayland-capable process tree (mako, swaybar, etc.),
no matter who/what is calling the script.

Verified on tadbit: pre-fix toggle off killed swayidle permanently.
Post-fix: toggle off restarts swayidle successfully, env inherited
from mako's /proc/PID/environ.
2026-06-23 21:51:09 -04:00

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#!/bin/bash
# start-swayidle.sh — canonical swayidle startup for the Sway session.
#
# Single source of truth for the swayidle command. Invoked from:
# 1. ~/.config/sway/config: exec $HOME/.config/sway/start-swayidle.sh
# 2. ~/.config/sway/caffeine.sh: after killall swayidle, to re-arm
#
# Why a wrapper instead of inlining the command in sway/config? Because
# caffeine.sh needs to RESTART swayidle after killing it, and the restart
# must use the same timeouts and lock command as the original. Hardcoding
# it twice drifts (see git log — swayidle line in caffeine.sh got out of
# sync with the one in sway/config, so toggling caffeine off would
# silently change your lock command and timeout values).
#
# Env: this script is run by:
# - sway at session start, with the full Wayland/Sway env (correct)
# - caffeine.sh from waybar's on-click, with NO Wayland env (broken — see below)
# When run from caffeine.sh, swayidle needs WAYLAND_DISPLAY to talk to the
# compositor. We probe /proc for the env of an already-running Wayland client
# (mako, swaybar, foot, etc.) and inherit WAYLAND_DISPLAY / DISPLAY /
# DBUS_SESSION_BUS_ADDRESS / XDG_RUNTIME_DIR from it. This is the same
# trick `dbus-update-activation-environment` uses internally, just per-process.
#
# Returns: never. Runs as the foreground process; sway's exec replaces the
# shell with this script, and swayidle takes over. When started from
# caffeine.sh, the script is backgrounded (&) and this function returns.
set -e
# --- 1. Restore Wayland env if missing -----------------------------------
# The bug we're fixing: clicking the caffeine button runs this script
# from waybar's on-click context, which doesn't inherit sway's env.
# swayidle and lock-fancy.sh both call swaymsg/grim which need
# WAYLAND_DISPLAY — without it, swayidle silently exits and the user
# has NO idle lock at all (the worst possible failure mode: looks normal
# in the bar, but auto-lock is silently dead).
if [[ -z "$WAYLAND_DISPLAY" && -z "$SWAYSOCK" ]]; then
# Find any running Wayland client and steal its env. mako (notification
# daemon) is always present and always has the right env.
for pid in /proc/[0-9]*; do
[[ -r "$pid/environ" ]] || continue
candidate=$(tr '\0' '\n' < "$pid/environ" 2>/dev/null | grep -E '^(WAYLAND_DISPLAY|DBUS_SESSION_BUS_ADDRESS|XDG_RUNTIME_DIR|DISPLAY)=' || true)
if [[ -n "$candidate" ]]; then
export $candidate
break
fi
done
fi
# --- 2. Start swayidle ----------------------------------------------------
# If invoked from sway's `exec` line (config), swayidle replaces this shell
# and runs forever. If invoked from caffeine.sh (backgrounded with &), it
# runs as a child of the parent shell and caffeine.sh returns immediately.
exec swayidle -w \
timeout 300 "$HOME/.config/sway/lock-fancy.sh" \
timeout 600 'swaymsg "output * power off"' \
resume 'swaymsg "output * power on"' \
before-sleep "$HOME/.config/sway/lock-fancy.sh"