Support AI opponents in two-faction games

tests/two-player-controls.test.ts

@@ -25,6 +25,7 @@ function render(game: GameView, pendingEntry = false) {
   return renderToStaticMarkup(createElement(TwoPlayerControls, {
     game, disabled: pendingEntry, pendingEntry, entryRoom: game.code, entryProblem: '',
     retryDisabled: false, onModeChange: noop, onSwitch: noop, onAdd: noop, onRetry: noop,
+    onAddBot: noop, onAddControlledBot: noop,
   }));
 }
 
@@ -51,3 +52,53 @@ void test('an unresolved request stays visible with an explicit retry', () => {
   assert.match(html, /never retried automatically/);
   assert.match(html, /<select[^>]*disabled/);
 });
+
+void test('host may add a computer opponent when the second controller slot is empty', () => {
+  const game = {
+    ...base,
+    players: [base.players[0]],
+    twoPlayerControllers: { version: 1 as const, controllers: [{ id: 'a', seats: ['a'] }] },
+    controlledFactionSeats: [{ id: 'a', name: 'Ali', faction: 'atreides' as const }],
+  };
+  const html = render(game);
+  assert.match(html, /Add an AI player/);
+  assert.match(html, /The AI plays each faction independently/);
+  for (const difficulty of ['Easy', 'Medium', 'Hard', 'Brutal'])
+    assert.match(html, new RegExp(`value="${difficulty}"`));
+  assert.match(html, /value="harkonnen"/);
+  assert.doesNotMatch(html, /<option[^>]*value="atreides"/);
+});
+
+void test('host adds the second AI faction only for an incomplete AI controller', () => {
+  const human = base.players[0];
+  const ai = { ...base.players[1], bot: 'Hard' as const };
+  const game = {
+    ...base,
+    players: [human, ai],
+    twoPlayerControllers: { version: 1 as const, controllers: [
+      { id: 'a', seats: ['a'] }, { id: 'b', seats: ['b'] },
+    ] },
+    controlledFactionSeats: [{ id: 'a', name: 'Ali', faction: 'atreides' as const }],
+  };
+  const html = render(game);
+  assert.match(html, /Player 2 \(AI\): Harkonnen/);
+  assert.match(html, /Add the AI player’s second faction/);
+  assert.match(html, /Add AI second faction/);
+  assert.doesNotMatch(html, /<option[^>]*value="harkonnen"/);
+  const nonHost = render({ ...game, me: 'b' });
+  assert.doesNotMatch(nonHost, /Add AI second faction/);
+  const complete = render({ ...game, twoPlayerControllers: { version: 1, controllers: [
+    { id: 'a', seats: ['a'] }, { id: 'b', seats: ['b', 'c'] },
+  ] } });
+  assert.doesNotMatch(complete, /Add AI second faction/);
+});
+
+void test('a human opponent does not expose controls to add an AI faction to their seat', () => {
+  const game = {
+    ...base,
+    twoPlayerControllers: { version: 1 as const, controllers: [
+      { id: 'a', seats: ['a', 'c'] }, { id: 'b', seats: ['b'] },
+    ] },
+  };
+  assert.doesNotMatch(render(game), /Add AI second faction|Add an AI player/);
+});