fix(firefox): copy the wallpaper, Firefox won't follow the link

The darknix.png symlink out of the profile left the new tab blank, even
after a restart: Firefox's sandbox does not follow it. udt-accent now
copies the wallpaper over the slot on every change instead, removing any
leftover link first so the copy cannot write through it into the
wallpaper. install.sh no longer makes the link.

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

3 files changed, 23 insertions, 13 deletions

diff --git a/AGENTS.md b/AGENTS.md
index c1ab004..3a7401d 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -271,11 +271,11 @@ write lands after `wallp` has already run `wal --theme`, so it wins; reorder
 those two and pywal's wallpaper-derived colours come back.
 
 Firefox's new tab shows the wallpaper itself, not a colour. FF Ultima picks
-the new tab background from a fixed list of images by pref, and `install.sh`
-links its `walls/darknix.png` slot to `~/.cache/udt/wpaper`; selecting it once
+the new tab background from a fixed list of images by pref, and `udt-accent`
+copies the wallpaper over its `walls/darknix.png` slot; selecting it once
 (`user.theme.wallpaper.darknix` in `about:config`) is the only manual step.
-Firefox revalidates the file on each new tab, so a wallpaper change reaches a
-running browser without a restart.
+A copy, not a symlink: Firefox's sandbox will not follow a link out of the
+profile, and the new tab stays blank.
 
 Not everything tracks the wallpaper. rofi, quickshell, Hyprland borders,
 hyprlock's border (through `~/.cache/udt/hyprlock-border.conf`), Sublime's
diff --git a/bin/udt-accent b/bin/udt-accent
index 69698d1..2dfc9a0 100755
--- a/bin/udt-accent
+++ b/bin/udt-accent
@@ -19,6 +19,7 @@ import json
 import math
 import os
 import re
+import shutil
 import subprocess
 import sys
 import tempfile
@@ -63,6 +64,8 @@ PALETTE_RASI = Path.home() / ".config" / "rofi" / "udt" / "palette.rasi"
 # install.sh symlinks ~/.cache/wal/colors.json here, so the real file lives
 # with the rest of the palette and ~/.cache/wal holds nothing but that link.
 COLORS_JSON = CACHE / "colors.json"
+# FF Ultima's new tab background slots. darknix.png is the one udt fills.
+FIREFOX_WALLS = "chrome/theme/color-schemes/walls"
 
 # The SDDM theme's live palette. ~/.cache is 0700 and unreachable to the sddm
 # user, ~/.local/share is 0755, so the file has to live here. Root symlinks
@@ -387,6 +390,21 @@ def write_colors_json(name, image):
     subprocess.run(["pywalfox", "update"], capture_output=True, check=False)
 
 
+def write_firefox(image):
+    """Copy the wallpaper into FF Ultima's darknix.png new tab slot.
+
+    A copy, not a link: Firefox's sandbox refuses to follow a symlink out of
+    the profile, and the new tab shows nothing. Every profile without FF
+    Ultima is skipped.
+    """
+    for walls in (Path.home() / ".mozilla" / "firefox").glob(f"*/{FIREFOX_WALLS}"):
+        dest = walls / "darknix.png"
+        # A leftover link would make copyfile write through it into the
+        # wallpaper itself.
+        dest.unlink(missing_ok=True)
+        shutil.copyfile(image, dest)
+
+
 def rewrite(path, pattern, value):
     """Replace group 1's tail in the first line matching pattern with value.
 
@@ -541,6 +559,7 @@ def main(image):
     write_sublime(name)
     write_sddm(name, image)
     write_colors_json(name, image)
+    write_firefox(image)
     # Before the helpers below start, which build and stage these two.
     write_grub(name)
     write_homepage(name)
diff --git a/install.sh b/install.sh
index b0fd835..7a78f80 100755
--- a/install.sh
+++ b/install.sh
@@ -123,15 +123,6 @@ fi
 mkdir -p "$HOME/.cache/wal"
 ln -sfn "$HOME/.cache/udt/colors.json" "$HOME/.cache/wal/colors.json"
 
-# Firefox's new tab background. FF Ultima picks it from a fixed list of
-# images by pref; its darknix.png slot is pointed at the wallpaper udt-accent
-# tracks, so selecting it once (user.theme.wallpaper.darknix in about:config)
-# makes the new tab follow every wallpaper change. Skipped per profile
-# without FF Ultima.
-for walls in "$HOME"/.mozilla/firefox/*/chrome/theme/color-schemes/walls; do
-    [ -d "$walls" ] && ln -sfn "$HOME/.cache/udt/wpaper" "$walls/darknix.png"
-done
-
 # The rofi menus are bound by name in hypr-theme's keybindings, so they keep
 # the names they had when they lived loose in ~/bin.
 for f in udt-accent udt-grub udt-keyboard udt-steps udt-palette udt-machine-name udt-powermenu.sh udt-launcher.sh qar-scrotmenu.sh; do