🐛 fix(channel): keep regional repos when switching to dev

- 🛡️ refuse a dev checkout that lacks this machine's region profile before linking it, since its own refresh would silently replace the regional pacman files
- ✅ isolate channel tests from the host region marker

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

test/shell.d/channel-test.sh

@@ -113,6 +113,7 @@ run_channel() {
   : >"$log_file"
   OMARCHY_CHANNEL_TEST_LOG="$log_file" \
     OMARCHY_PATH="${OMARCHY_TEST_PATH:-$package_root}" \
+    OMARCHY_REGION_FILE="${OMARCHY_TEST_REGION_FILE:-$test_tmp/no-region}" \
     HOME="$test_tmp/home" \
     PATH="$stub_bin:$ROOT/bin:$PATH" \
     "${OMARCHY_TEST_PATH:-$package_root}/bin/omarchy-channel-set" "$@"
@@ -190,6 +191,21 @@ fi
 assert_log_line $'link\t'"$checkout"$'\t--no-reboot' "switching back to dev links ~/omarchy"
 pass "switching back to dev reuses the existing ~/omarchy checkout"
 
+printf 'cn\n' >"$test_tmp/region"
+if OMARCHY_TEST_REGION_FILE="$test_tmp/region" run_channel dev >"$test_tmp/region.out" 2>"$test_tmp/region.err"; then
+  fail "dev refuses a checkout without this machine's region"
+fi
+grep -q "does not support the 'cn' region" "$test_tmp/region.err" || fail "dev explains the missing region" "$(cat "$test_tmp/region.err")"
+if grep -Eq $'^(link|refresh)\t' "$log_file"; then
+  fail "dev refuses before linking or refreshing pacman" "$(cat "$log_file")"
+fi
+pass "dev refuses a checkout without the region before touching pacman"
+
+mkdir -p "$checkout/default/regions/cn"
+touch "$checkout/bin/omarchy-apply-pacman"
+OMARCHY_TEST_REGION_FILE="$test_tmp/region" run_channel dev
+assert_log_line $'refresh\tedge' "dev proceeds with a checkout that supports the region"
+
 current_channel() {
   OMARCHY_TEST_VERSION_CHANNEL="$1" \
     OMARCHY_TEST_PACKAGES="$2" \