Text channels between mumh5 users; drag channels in front of or behind another

Text channels are real Mumble channels with a marker in the description.
Their messages travel as plugin data to everyone on the server, are kept
by the clients and handed to people who connect later.

Channels can be dropped in front of or behind another channel, with a
line where they land. A description preview no longer sticks after a drop.

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

test/channel-order.test.ts

@@ -0,0 +1,47 @@
+import { test } from 'node:test';
+import assert from 'node:assert/strict';
+import { planMove, byOrder, type Ordered } from '../src/core/channel-order.ts';
+
+const ch = (id: number, name: string, position = 0): Ordered => ({ id, name, position });
+// The order everyone sees once the plan is applied
+function after(siblings: Ordered[], moved: Ordered, index: number): string[] {
+  const plan = planMove(siblings, moved, index);
+  const all = [...siblings.filter(c => c.id !== moved.id), moved].map(c => ({ ...c, position: plan.find(u => u.id === c.id)?.position ?? c.position }));
+  return all.sort(byOrder).map(c => c.name);
+}
+
+test('a spot that the name already gives needs no change', () => {
+  const list = [ch(1, 'Alpha'), ch(3, 'Gamma')];
+  assert.deepEqual(planMove(list, ch(2, 'Beta'), 1), []);
+});
+
+test('one change when there is room between the neighbours', () => {
+  const list = [ch(1, 'Alpha', 0), ch(2, 'Beta', 5), ch(3, 'Gamma', 9)];
+  const plan = planMove(list, ch(3, 'Gamma', 9), 1);
+  assert.equal(plan.length, 1);
+  assert.deepEqual(after(list, ch(3, 'Gamma', 9), 1), ['Alpha', 'Gamma', 'Beta']);
+});
+
+test('to the front and to the end', () => {
+  const list = [ch(1, 'Alpha'), ch(2, 'Beta'), ch(3, 'Gamma')];
+  assert.deepEqual(planMove(list, list[2], 0), [{ id: 3, position: -1 }]);
+  assert.deepEqual(planMove(list, list[0], 2), [{ id: 1, position: 1 }]);
+});
+
+test('channels that all share a position are numbered again when the name does not fit', () => {
+  const list = [ch(1, 'Alpha'), ch(2, 'Beta'), ch(3, 'Gamma'), ch(4, 'Delta')];
+  // Sorted: Alpha, Beta, Delta, Gamma. Gamma between Alpha and Beta.
+  assert.deepEqual(after(list, list[2], 1), ['Alpha', 'Gamma', 'Beta', 'Delta']);
+  assert.ok(planMove(list, list[2], 1).length > 1);
+});
+
+test('every spot works, for a channel of the row and for one coming from elsewhere', () => {
+  const list = [ch(1, 'b', 0), ch(2, 'a', 0), ch(3, 'c', 1), ch(4, 'd', 1), ch(5, 'e', 7)];
+  const sorted = [...list].sort(byOrder);
+  for (const moved of [...list, ch(9, 'new', 1)]) {
+    const rest = sorted.filter(c => c.id !== moved.id).map(c => c.name);
+    for (let i = 0; i <= rest.length; i++) {
+      assert.deepEqual(after(list, moved, i), [...rest.slice(0, i), moved.name, ...rest.slice(i)], `${moved.name} to ${i}`);
+    }
+  }
+});