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

1 files changed, 8 insertions, 1 deletions

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()