Let the Elsewhen migration carry on without a shell to ask

A bare `omarchy-shell shell rescanPlugins` exits 1 when no shell answers on the caller's tree, and omarchy-migrate runs migrations under `set -e`, so an update run from a TTY or over ssh, or one whose shell had gone down while the package replaced its QML, died at "omarchy-shell is not running" before its post-update hooks, shell restart and reboot prompt, and re-failed the same way every time until a shell could be asked. The rescan is now best-effort, like `omarchy-bar put` already is and like #11117 makes the plugin commands' closing rescan: the update restarts the shell once the migrations are through, and a session without one has no bar to place on. An unknown widget on a live shell still leaves the migration pending.

test/shell.d/elsewhen-default-migration-test.sh

@@ -18,7 +18,17 @@ SH
 cat >"$test_dir/bin/omarchy-shell" <<'SH'
 #!/bin/bash
 printf '%s\n' "$*" >>"$CALL_LOG"
-[[ $2 != "rescanPlugins" ]] || exit "${SCAN_STATUS:-0}"
+quiet=0
+if [[ $1 == "-q" ]]; then
+  quiet=1
+  shift
+fi
+if [[ ${SHELL_ABSENT:-0} == 1 ]]; then
+  (( quiet )) && exit 0
+  echo "omarchy-shell is not running" >&2
+  exit 1
+fi
+[[ $2 != "rescanPlugins" ]] || exit 0
 printf '%s\n' "${TEST_PUT_RESULT:-ok}"
 SH
 cat >"$test_dir/bin/omarchy-restart-shell" <<'SH'
@@ -50,7 +60,7 @@ run_migration
 [[ ! -e $ROOT/config/omarchy/plugins/omacom.elsewhen && ! -L $ROOT/config/omarchy/plugins/omacom.elsewhen ]] || fail "fresh installs do not ship a user plugin link"
 pass "migration and fresh installs rely on the packaged plugin directory"
 
-expected=$'package elsewhen\nshell rescanPlugins\nshell putBarWidget omacom.elsewhen {"before":"omarchy.clock"}'
+expected=$'package elsewhen\n-q shell rescanPlugins\nshell putBarWidget omacom.elsewhen {"before":"omarchy.clock"}'
 [[ $(cat "$CALL_LOG") == "$expected" ]] || fail "install, scan and placement run in order" "$(cat "$CALL_LOG")"
 pass "real bar helper enables and places before the clock without restarting during reload"
 
@@ -80,10 +90,23 @@ run_migration "$ROOT"
 [[ $(readlink "$plugin") == "$test_dir/custom-plugin" ]] || fail "existing symlink is preserved"
 pass "existing symlink is preserved, including a missing target"
 
-for failure in 'SCAN_STATUS=1' 'TEST_PUT_RESULT=unknown'; do
-  if env "$failure" HOME="$test_dir/home" OMARCHY_PATH="$ROOT" PATH="$test_dir/bin:$ROOT/bin:$PATH" \
-    bash -euo pipefail "$test_dir/migration.sh" >"$test_dir/output" 2>&1; then
-    fail "$failure must leave the migration pending"
-  fi
-  pass "$failure leaves the migration pending"
-done
+
+if env TEST_PUT_RESULT=unknown HOME="$test_dir/home" OMARCHY_PATH="$ROOT" PATH="$test_dir/bin:$ROOT/bin:$PATH" \
+  bash -euo pipefail "$test_dir/migration.sh" >"$test_dir/output" 2>&1; then
+  fail "an unknown widget must leave the migration pending"
+fi
+pass "an unknown widget leaves the migration pending"
+
+# An update with no shell to ask, from a TTY or with the shell down, still
+# finishes: the package and link land, the placement is skipped, and the update
+# restarts the shell afterwards.
+rm "$plugin"
+: >"$CALL_LOG"
+if ! env SHELL_ABSENT=1 OMARCHY_SHELL_ABSENT_ATTEMPTS=1 HOME="$test_dir/home" OMARCHY_PATH="$ROOT" PATH="$test_dir/bin:$ROOT/bin:$PATH" \
+  bash -euo pipefail "$test_dir/migration.sh" >"$test_dir/output" 2>&1; then
+  fail "an absent shell must not fail the migration" "$(cat "$test_dir/output")"
+fi
+grep -q "omacom.elsewhen was not put on the bar" "$test_dir/output" || fail "an absent shell is reported" "$(cat "$test_dir/output")"
+[[ $(readlink "$plugin") == "$test_dir/packaged/shell/plugins/omacom.elsewhen" ]] || fail "the package and plugin link land without a shell"
+[[ $(cat "$CALL_LOG") == "$expected" ]] || fail "the rescan is best-effort and the put is still asked" "$(cat "$CALL_LOG")"
+pass "an absent shell leaves the update running with the package and link in place"