launcher-menu: detect missing icon fallbacks on switch (iconFallbacks.enable/extra)

README.md

@@ -195,7 +195,8 @@ menu list every desktop entry, including terminals such as Konsole.
 | `steamFrame.launcherMenu.grid.enable` | bool | `false` | Show the "+" menu's programs as a grid of tiles (large icon, name below) instead of a list. |
 | `steamFrame.launcherMenu.grid.columns` | int, 1-8 | `4` | Tiles per row (popup is 300 px wide: 3 ≈ 92 px, 4 ≈ 68 px, 5 ≈ 53 px tiles). |
 | `steamFrame.launcherMenu.grid.maxRows` | null or positive int | `null` | Rows visible at once, the rest scrolls. `null`: fill up to the menu's max height (600 px). |
-| `steamFrame.launcherMenu.iconFallbacks` | list of str | `[ "utilities-terminal" "preferences-system" ]` | Icon names installed as hicolor copies of Breeze app icons, so the "+" menu shows them (Konsole, KDE System Settings). `[ ]`: none. Takes effect after a Steam restart. |
+| `steamFrame.launcherMenu.iconFallbacks.enable` | bool | `true` | On every switch, link hicolor fallbacks (Breeze app icons) for desktop entries whose icon Steam can't find, so the "+" menu shows them (SteamOS: Konsole, KDE System Settings). `false` removes the links. See [Icon fallbacks](#icon-fallbacks-launchermenuiconfallbacks). |
+| `steamFrame.launcherMenu.iconFallbacks.extra` | list of str | `[ ]` | Further icon names to provide even if no desktop entry the scan sees uses them. |
 | `steamFrame.dashboard.windowMaxScale` | null or number | `null` | Largest resize-handle scale of SteamVR dashboard windows, relative to their default size. `null`: stock (2). See [Dashboard windows](#dashboard-windows-dashboard). |
 | `steamFrame.dashboard.windowDistance.{world,theater,dashboard}.{min,max}` | null or number (m) | `null` | How close / far grabbed windows can be pulled in / pushed back. `null`: stock (world 0.25-5, theater 1-6, dashboard 0.3-4 m). |
 | `steamFrame.dashboard.steamCloseButton.enable` | bool | `false` | Close (X) button on the dashboard's Steam window: switches to the previous window, or leaves just the dashboard bar. See [Steam close button](#steam-close-button-dashboardsteamclosebuttonenable). |
@@ -551,19 +552,30 @@ desktop's icon theme. Konsole (`Icon=utilities-terminal`) and KDE System
 Settings (`Icon=preferences-system`), which SteamOS ships, have their icons
 only in Breeze, so they show up without an icon in the "+" menu.
 
-**Fix:** for each name in `iconFallbacks` (default: those two), the largest
-Breeze app icon from nixpkgs' `kdePackages.breeze-icons` is installed as
-`~/.nix-profile/share/icons/hicolor/scalable/apps/<name>.svg`
-(`~/.nix-profile/share` is on Steam's `XDG_DATA_DIRS`); desktop entries are
-left alone. Add names for other programs that lack an icon (the `Icon=`
-value of their desktop entry), e.g.
-`iconFallbacks = [ "utilities-terminal" "preferences-system" "system-file-manager" ];`;
-`[ ]` installs nothing. A name Breeze has no app icon for fails the build
-with an error naming it.
+**Fix:** on every `home-manager switch`, a small activation script looks
+through the desktop entries Steam sees (`applications/` in
+`~/.local/share` and Steam's `XDG_DATA_DIRS`; an entry shadowed by one with
+the same desktop-file ID, and `Hidden`/`NoDisplay` entries, are skipped).
+For each `Icon=` name that no hicolor theme dir (or `pixmaps`) has but
+nixpkgs' `kdePackages.breeze-icons` app icons do, it links the largest
+Breeze SVG as `~/.local/share/icons/hicolor/scalable/apps/<name>.svg`.
+Desktop entries are left alone. `iconFallbacks.extra` adds names to
+provide even if no scanned entry uses them (a name Breeze lacks is
+reported and skipped). The links made are listed in
+`~/.local/state/steam-frame-nix/icon-fallbacks`; links no longer needed are
+removed, and `iconFallbacks.enable = false` removes them all. Only those
+links (still pointing into a breeze-icons store path) are ever removed;
+other files in the icon dir are never touched. Programs installed later get
+their fallback on the next switch.
 
-**Caveat:** Steam caches the icon lookup (GTK icon cache) for its lifetime,
-and files in the Nix store all have the same 1970 mtime, so new icons show
-up only after Steam is restarted (e.g. a reboot), not on the next switch.
+`iconFallbacks` used to be a list of icon names; setting a list now fails
+evaluation with a message: use `iconFallbacks.extra` for additional names,
+`iconFallbacks.enable = false` for what `[ ]` meant.
+
+A running Steam picks up the change without a restart: it caches the icon
+theme (GTK) and rescans it only when a theme directory's mtime changes, so
+the script bumps the mtime of `~/.local/share/icons/hicolor` whenever it
+adds or removes links.
 
 ### Dashboard windows (`dashboard.*`)
 

modules/launcher-menu.nix

@@ -23,32 +23,23 @@
 # iconFallbacks is not a patch: Steam's scan of host programs resolves a
 # desktop entry's Icon= name only in the hicolor icon theme (and pixmaps),
 # so programs whose icon exists only in the desktop's Breeze theme (SteamOS'
-# Konsole and KDE System Settings) have no icon in the menu. Hicolor copies
-# from nixpkgs' Breeze are installed into the profile (~/.nix-profile/share
-# is on Steam's XDG_DATA_DIRS).
+# Konsole and KDE System Settings) have no icon in the menu. On every switch,
+# launcher-menu/icon-fallbacks.sh looks through the desktop entries Steam
+# sees and links the missing icons that nixpkgs' Breeze has into
+# ~/.local/share/icons/hicolor (see the script). Until 2026-09 iconFallbacks
+# was a list of names; setting a list now fails with a message pointing to
+# enable/extra.
 { config, lib, pkgs, ... }:
 let
   cfg = config.steamFrame.launcherMenu;
   inherit (import ./lib { inherit pkgs; }) mkPatch;
   sharedJSContext = { title = "SharedJSContext"; };
 
-  # Largest Breeze app icon (all are SVG) as hicolor/scalable/apps/<name>.svg.
-  breezeApps = "${pkgs.kdePackages.breeze-icons}/share/icons/breeze/apps";
-  iconFallbacks = pkgs.runCommand "launcher-menu-icon-fallbacks" { } ''
-    dir=$out/share/icons/hicolor/scalable/apps
-    mkdir -p $dir
-    for name in ${lib.escapeShellArgs cfg.iconFallbacks}; do
-      src=
-      for size in 64 48 32 24 22 16; do
-        if [ -e "${breezeApps}/$size/$name.svg" ]; then src="${breezeApps}/$size/$name.svg"; break; fi
-      done
-      if [ -z "$src" ]; then
-        echo "steamFrame.launcherMenu.iconFallbacks: no Breeze app icon \"$name\" (${breezeApps}/<size>/$name.svg)" >&2
-        exit 1
-      fi
-      cp -L "$src" "$dir/$name.svg"
-    done
-  '';
+  iconFallbacks = pkgs.writeShellApplication {
+    name = "steam-frame-icon-fallbacks";
+    runtimeInputs = [ pkgs.coreutils pkgs.findutils pkgs.gawk ];
+    text = builtins.readFile ./launcher-menu/icon-fallbacks.sh;
+  };
 in {
   imports = [ ./steam-ui-patches.nix ];
 
@@ -122,23 +113,76 @@ in {
       };
     };
     iconFallbacks = lib.mkOption {
-      type = lib.types.listOf (lib.types.strMatching "[A-Za-z0-9._+-]+");
-      default = [ "utilities-terminal" "preferences-system" ];
-      example = [ "utilities-terminal" "preferences-system" "system-file-manager" ];
+      default = { };
       description = ''
-        Icon names (Icon= of desktop entries) installed as hicolor icons,
-        copied from nixpkgs' Breeze app icons, so the "+" menu shows them:
-        Steam resolves program icons only in the hicolor theme, not in the
-        desktop's Breeze theme. The default covers the entries SteamOS ships
-        whose icons exist only in Breeze: Konsole (utilities-terminal) and
-        KDE System Settings (preferences-system). A name Breeze has no app
-        icon for fails the build, naming it. [] installs nothing. Steam
-        picks up new icons only after a restart.
+        Hicolor fallbacks for program icons only the desktop's Breeze theme
+        has, so the "+" menu shows them: Steam resolves program icons only in
+        the hicolor theme.
       '';
+      # The option used to be a list of icon names: keep a list from being
+      # silently misread and fail with a message instead (see the assertion).
+      type = lib.types.coercedTo (lib.types.listOf lib.types.str)
+        (names: { legacyList = names; })
+        (lib.types.submodule {
+          options = {
+            enable = lib.mkOption {
+              type = lib.types.bool;
+              default = true;
+              description = ''
+                On every switch, look through the desktop entries Steam sees
+                (XDG data dirs, shadowed and Hidden/NoDisplay entries skipped)
+                and, for each Icon= name no hicolor theme dir (or pixmaps)
+                has but nixpkgs' Breeze app icons do (SteamOS: Konsole's
+                utilities-terminal, KDE System Settings' preferences-system),
+                link the Breeze SVG as
+                ~/.local/share/icons/hicolor/scalable/apps/<name>.svg. Links
+                no longer needed are removed; only links made by this option
+                (listed in ~/.local/state/steam-frame-nix/icon-fallbacks) are
+                ever touched. false removes them all.
+              '';
+            };
+            extra = lib.mkOption {
+              type = lib.types.listOf (lib.types.strMatching "[A-Za-z0-9._+-]+");
+              default = [ ];
+              example = [ "system-file-manager" ];
+              description = ''
+                Icon names to provide even if no desktop entry the scan sees
+                uses them (still only if hicolor lacks them). A name Breeze
+                has no app icon for is reported on switch and skipped.
+              '';
+            };
+            legacyList = lib.mkOption {
+              type = lib.types.nullOr (lib.types.listOf lib.types.str);
+              default = null;
+              internal = true;
+              visible = false;
+            };
+          };
+        });
     };
   };
 
-  config.home.packages = lib.optional (cfg.iconFallbacks != [ ]) iconFallbacks;
+  config.assertions = [ {
+    assertion = cfg.iconFallbacks.legacyList == null;
+    message = ''
+      steamFrame.launcherMenu.iconFallbacks is no longer a list of icon names
+      (set to ${builtins.toJSON cfg.iconFallbacks.legacyList}). Use
+        iconFallbacks.enable = true;   # default: utilities-terminal, preferences-system
+        iconFallbacks.extra = [ ... ]; # further names
+      or iconFallbacks.enable = false; for none (what [ ] used to mean).
+    '';
+  } ];
+
+  # After installPackages, so the new profile's desktop entries and icons count.
+  # Disabled, the script removes its links (no BREEZE_APPS).
+  config.home.activation.steamFrameIconFallbacks =
+    lib.hm.dag.entryAfter [ "writeBoundary" "installPackages" ] (
+      if cfg.iconFallbacks.enable then ''
+        run env BREEZE_APPS=${pkgs.kdePackages.breeze-icons}/share/icons/breeze/apps \
+          ${lib.getExe iconFallbacks} ${lib.escapeShellArgs cfg.iconFallbacks.extra}
+      '' else ''
+        run ${lib.getExe iconFallbacks}
+      '');
 
   config.steamFrame.uiPatches.patches =
     lib.optional cfg.sort {

modules/launcher-menu/icon-fallbacks.sh

@@ -0,0 +1,125 @@
+# Hicolor fallbacks for desktop entry icons that only Breeze has.
+#
+# Usage: steam-frame-icon-fallbacks [EXTRA_NAME...]
+#   BREEZE_APPS=<breeze-icons>/share/icons/breeze/apps: link the Icon= names
+#     of the desktop entries Steam sees (plus EXTRA_NAMEs) that no hicolor
+#     theme dir has but Breeze does, as
+#     $XDG_DATA_HOME/icons/hicolor/scalable/apps/<name>.svg -> Breeze's SVG.
+#   BREEZE_APPS unset: remove all links made before (disabled).
+# Links made are listed in a manifest; only those, and only while they still
+# point into a breeze-icons store path, are ever removed. Nothing else in the
+# icon dir is touched.
+
+data_home=${XDG_DATA_HOME:-$HOME/.local/share}
+dest=$data_home/icons/hicolor/scalable/apps
+manifest=${XDG_STATE_HOME:-$HOME/.local/state}/steam-frame-nix/icon-fallbacks
+# Steam's data dirs (XDG_DATA_HOME, then its XDG_DATA_DIRS on SteamOS), not
+# the caller's: switches usually run from the nested desktop session.
+data_dirs=(
+  "$data_home"
+  "$HOME/.local/share/flatpak/exports/share"
+  /var/lib/flatpak/exports/share
+  /usr/local/share
+  /usr/share
+  "$HOME/.nix-profile/share"
+  /nix/var/nix/profiles/default/share
+)
+shopt -s nullglob
+
+ours() { [[ -L $1 && $(readlink "$1") == /nix/store/*-breeze-icons-*/* ]]; }
+
+# Does Steam already find <name> (hicolor in any data dir, or pixmaps)?
+# Our own links don't count.
+resolves() {
+  local d f
+  for d in "$HOME/.icons" "${data_dirs[@]/%//icons}"; do
+    for f in "$d"/hicolor/*/*/"$1".{png,svg,xpm}; do
+      ours "$f" || return 0
+    done
+  done
+  for d in "${data_dirs[@]}"; do
+    for f in "$d"/pixmaps/"$1".{png,svg,xpm}; do [[ ! -e $f ]] || return 0; done
+  done
+  return 1
+}
+
+# Largest Breeze app icon for <name> (Breeze's app icons are all SVG).
+breeze() {
+  local size
+  for size in 64 48 32 24 22 16; do
+    if [[ -e $BREEZE_APPS/$size/$1.svg ]]; then echo "$BREEZE_APPS/$size/$1.svg"; return; fi
+  done
+  return 1
+}
+
+# Icon= of a desktop entry, unless it is Hidden/NoDisplay or not a plain icon
+# name (e.g. an absolute path).
+entry_icon() {
+  awk -F= '
+    /^\[/ { group = ($0 ~ /^\[Desktop Entry\][[:space:]]*$/); next }
+    !group { next }
+    { key = $1; sub(/[[:space:]]+$/, "", key); val = substr($0, index($0, "=") + 1)
+      gsub(/^[[:space:]]+|[[:space:]\r]+$/, "", val) }
+    (key == "Hidden" || key == "NoDisplay") && val == "true" { skip = 1 }
+    key == "Icon" { icon = val }
+    END { if (!skip && icon ~ /^[A-Za-z0-9._+-]+$/) print icon }
+  ' "$1"
+}
+
+# Wanted: extra names, and the icons of the entries Steam sees (the first
+# entry with a given desktop-file ID wins, like in the menu).
+declare -A wanted=() seen=()
+if [[ -n ${BREEZE_APPS:-} ]]; then
+  for name in "$@"; do wanted[$name]=extra; done
+  for d in "${data_dirs[@]}"; do
+    [[ -d $d/applications ]] || continue
+    while IFS= read -r -d '' f; do
+      id=${f#"$d/applications/"}; id=${id//\//-}
+      [[ -z ${seen[$id]:-} ]] || continue
+      seen[$id]=1
+      icon=$(entry_icon "$f")
+      [[ -z $icon ]] || wanted[$icon]=${wanted[$icon]:-$id}
+    done < <(find -L "$d/applications" -name '*.desktop' -print0 2>/dev/null)
+  done
+fi
+
+changed=
+linked=()
+for name in "${!wanted[@]}"; do
+  resolves "$name" && continue
+  if ! src=$(breeze "$name"); then
+    [[ ${wanted[$name]} != extra ]] || echo "icon fallbacks: Breeze has no app icon \"$name\" (extra)" >&2
+    continue
+  fi
+  link=$dest/$name.svg
+  if [[ -e $link || -L $link ]] && ! ours "$link"; then continue; fi   # not ours
+  linked+=("$name")
+  [[ $(readlink "$link") == "$src" ]] && continue
+  mkdir -p "$dest"
+  ln -sfn "$src" "$link"
+  echo "icon fallbacks: linked $name (${wanted[$name]})"
+  changed=1
+done
+
+# Remove links from earlier runs that are no longer wanted.
+if [[ -f $manifest ]]; then
+  while IFS= read -r name; do
+    [[ -n $name && " ${linked[*]} " != *" $name "* ]] || continue
+    if ours "$dest/$name.svg"; then
+      rm -f "$dest/$name.svg"
+      echo "icon fallbacks: removed $name"
+      changed=1
+    fi
+  done < "$manifest"
+fi
+
+if (( ${#linked[@]} )); then
+  mkdir -p "${manifest%/*}"
+  printf '%s\n' "${linked[@]}" | sort > "$manifest"
+else
+  rm -f "$manifest"
+fi
+
+# GTK rescans an icon theme only when a theme dir's mtime changes; bump it
+# so a running Steam sees the change.
+if [[ -n $changed && -d $data_home/icons/hicolor ]]; then touch "$data_home/icons/hicolor"; fi

template/home.nix

@@ -26,6 +26,9 @@
   #     closeOnLaunch = true;
   #     launchDebounce = 10;
   #     grid = { enable = true; columns = 4; maxRows = 4; };
+  #     # Icon fallbacks for programs without an icon in the menu are on by
+  #     # default; names to provide in addition to what the scan finds:
+  #     # iconFallbacks.extra = [ "system-file-manager" ];
   #   };
   #   # SteamVR dashboard windows: resizable up to 4x (stock 2x), pushed
   #   # back up to 10 m in the world / 12 m in theater mode (stock 5 / 6 m):