feat(palette): move the scheme selection out of the repo

The selector was tracked at palette/roles.conf, which made switching scheme a
committable change: the previous commit carried `scheme = tokyo-night` in its
diff purely because that was the theme running at the time.

Which theme a machine runs is local state, not a property of the project, so
the live file is now ~/.config/udt/roles.conf. install.sh seeds it from
palette/roles.conf.default on a first run and never overwrites it, so a
switch leaves the working tree clean and two machines sharing this repo can
run different schemes. udt-palette falls back to the seed when no live file
exists, so a bare checkout still generates.

This is the one exception to the repo holding the canonical copy of
everything, and AGENTS.md says so.

Verified: seeding on a missing file, the seed not overwriting an existing
choice, generation from the seed alone, and both selftests.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_015gbjA2bmswN8jyPDKzrvqe

6 files changed, 50 insertions, 23 deletions

diff --git a/AGENTS.md b/AGENTS.md
index fd40b57..0665bb9 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -16,13 +16,19 @@ the record of what changed and where the backups are.
 ## One palette, many consumers
 
 Colours are written down once. `palette/<scheme>.conf` holds them under the
-scheme's own names, `palette/roles-<scheme>.conf` says what each is for, and
-`palette/roles.conf` is a single `scheme = ` line selecting the pair.
-`bin/udt-palette` renders that into every consumer's own syntax; `install.sh`
-runs it first, before anything is linked.
+scheme's own names and `palette/roles-<scheme>.conf` says what each is for.
+`bin/udt-palette` renders that pair into every consumer's own syntax;
+`install.sh` runs it first, before anything is linked.
+
+**The scheme selection lives outside the repo**, in `~/.config/udt/roles.conf`,
+seeded from `palette/roles.conf.default` on a first install and never
+overwritten after. That is deliberate: which theme a machine runs is local
+state, so switching does not dirty the working tree and two machines sharing
+this repo can differ. It is the one exception to this repo holding the
+canonical copy of everything.
 
 Four schemes ship: `macchiato`, `tokyo-night`, `nord`, `dracula`. Switching is
-one line plus `./install.sh`.
+one line in `~/.config/udt/roles.conf` plus `./install.sh`.
 
 Generated files are gitignored, because tracking them would turn every scheme
 switch into a diff. Editing one is pointless: the next install overwrites it.
diff --git a/README.md b/README.md
index 2cd2a57..4eb59ba 100644
--- a/README.md
+++ b/README.md
@@ -35,11 +35,13 @@ GPLv2 only. See `LICENSE`.
 
 ## Changing the colour scheme
 
-Edit one line in `palette/roles.conf`:
+Edit one line in `~/.config/udt/roles.conf`:
 
     scheme = macchiato
 
-and run `./install.sh`. Ships with `macchiato`, `tokyo-night`, `nord` and
+and run `./install.sh`. That file is yours, not the repo's: `install.sh`
+creates it on a first run and never overwrites it, so switching scheme leaves
+the working tree clean. Ships with `macchiato`, `tokyo-night`, `nord` and
 `dracula`; rofi, dunst, conky, waybar, kitty, Firefox and quickshell all
 follow.
 
diff --git a/bin/udt-palette b/bin/udt-palette
index b2951c6..60a21fa 100755
--- a/bin/udt-palette
+++ b/bin/udt-palette
@@ -20,6 +20,13 @@ from pathlib import Path
 REPO = Path(__file__).resolve().parent.parent
 PALETTE_DIR = REPO / "palette"
 
+# The scheme selection is the user's, not the repo's, so it lives outside the
+# working tree: switching scheme should not show up as a diff, and two machines
+# sharing this repo can run different schemes. install.sh seeds it from
+# palette/roles.conf.default on a first run and never overwrites it after.
+SELECTOR = Path.home() / ".config" / "udt" / "roles.conf"
+SELECTOR_SEED = PALETTE_DIR / "roles.conf.default"
+
 
 def parse_conf(path):
     """Parse `key = value` lines into a dict, preserving order.
@@ -393,7 +400,7 @@ def main(argv):
         selftest()
         return 0
 
-    roles_path = PALETTE_DIR / "roles.conf"
+    roles_path = SELECTOR if SELECTOR.exists() else SELECTOR_SEED
     out_dir = REPO
     if "--roles" in argv:
         roles_path = Path(argv[argv.index("--roles") + 1]).expanduser()
diff --git a/install.sh b/install.sh
index 5489f46..9b849a3 100755
--- a/install.sh
+++ b/install.sh
@@ -13,6 +13,11 @@ mkdir -p "$target" "$HOME/bin" "$HOME/.cache/wal"
 # symlinked below is one of its outputs, so this has to run before anything is
 # linked. It fails loudly if a role names a colour the scheme does not define,
 # which is the whole point of keeping the colours in one place.
+selector="$HOME/.config/udt/roles.conf"
+if [ ! -f "$selector" ]; then
+    install -Dm644 "$repo/palette/roles.conf.default" "$selector"
+    echo "seeded $selector"
+fi
 "$repo/bin/udt-palette"
 
 # Theme files are symlinked individually; accent.rasi is NOT, it points at the
@@ -41,7 +46,7 @@ ln -sfn "$repo/bin/udt-palette" "$HOME/bin/udt-palette"
 # The generated configs for everything that is not rofi. These are copied
 # rather than symlinked: each app owns its config file and mixes theme keys
 # with settings that are none of this repo's business.
-scheme="$(sed -n 's/^scheme *= *//p' "$repo/palette/roles.conf")"
+scheme="$(sed -n 's/^scheme *= *//p' "$selector")"
 
 # waybar reads whichever themes/<name>.css style.css imports, so write the file
 # under the scheme's own name and repoint the import. The older per-flavour
diff --git a/palette/roles.conf b/palette/roles.conf
deleted file mode 100644
index a1ca448..0000000
--- a/palette/roles.conf
+++ /dev/null
@@ -1,14 +0,0 @@
-# Scheme selection.
-# Copyright (C) 2026 Danilo M. <danix@danix.xyz>
-# Licensed under the GNU General Public License v2 only.
-#
-# This is the one line to change to retheme the desktop. It picks a pair of
-# files: palette/<scheme>.conf, which holds the colours under the scheme's own
-# names, and palette/roles-<scheme>.conf, which says what each colour is for.
-#
-# Run ./install.sh afterwards. Every themed config is generated from that pair,
-# so nothing else needs editing.
-#
-# Available: macchiato, tokyo-night, nord, dracula
-
-scheme = tokyo-night
diff --git a/palette/roles.conf.default b/palette/roles.conf.default
new file mode 100644
index 0000000..556ef56
--- /dev/null
+++ b/palette/roles.conf.default
@@ -0,0 +1,21 @@
+# Scheme selection.
+# Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+# Licensed under the GNU General Public License v2 only.
+#
+# This file is the SEED. install.sh copies it to ~/.config/udt/roles.conf on a
+# first run and never touches it again, so edit the copy, not this one.
+#
+# The live file picks a pair: palette/<scheme>.conf, which holds the colours
+# under the scheme's own names, and palette/roles-<scheme>.conf, which says
+# what each colour is for.
+#
+#     $EDITOR ~/.config/udt/roles.conf    # change the scheme line
+#     ./install.sh                        # regenerate every config
+#
+# Keeping the selection outside the repo means switching scheme does not dirty
+# the working tree, and two machines sharing this repo can run different
+# schemes.
+#
+# Available: macchiato, tokyo-night, nord, dracula
+
+scheme = macchiato