fix(bot): finalize game on bot checkmate; harden driver dispatch

Extract endGame/finalizeIfEnded to game-end.ts so driver.ts can call
finalizeIfEnded after an applied move (fix: bot checkmate was not
setting game.status='finished'). Wrap entire dispatch() call in
try/catch for exception safety. Move lastSeenAnnouncementCount advance
to after successful dispatch so retry attempts see FSM rejection
announcements. Add checkmate-finalize test; lock retry-cap at 5 calls.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/server/src/bot/driver.ts

@@ -11,6 +11,7 @@ import { legalCandidates } from './candidates.js';
 import { handleCommit } from '../commit.js';
 import { buildView } from '../view.js';
 import { announce } from '../translator.js';
+import { finalizeIfEnded } from '../game-end.js';
 
 const RETRY_CAP = 5;
 
@@ -76,27 +77,31 @@ export class BotDriver {
 
     for (let attempt = 0; attempt < RETRY_CAP; attempt++) {
       const input = this.buildBrainInput(attemptHistory);
-      let action: BrainAction;
+      let outcome: { kind: 'done' } | { kind: 'retry'; entry: AttemptHistoryEntry };
       try {
-        action = await this.brain.decide(input);
+        const action = await this.brain.decide(input);
+        outcome = this.dispatch(action);
       } catch {
-        // Brain exception → bot resigns. CasualBrain only throws on zero
-        // candidates (impossible if shouldDecide passed).
+        // Brain exception OR programming error in dispatch. Safe failure: resign.
         this.botResign();
         return;
       }
-
-      const outcome = this.dispatch(action);
-      if (outcome.kind === 'done') return;
+      if (outcome.kind === 'done') {
+        this.lastSeenAnnouncementCount = this.game.announcements.length;
+        return;
+      }
       attemptHistory.push(outcome.entry);
     }
+    this.lastSeenAnnouncementCount = this.game.announcements.length;
     this.botResign();
   }
 
   private buildBrainInput(attemptHistory: AttemptHistoryEntry[]): BrainInput {
     const view = buildView(this.game, this.color);
     const sliceStart = this.lastSeenAnnouncementCount;
-    this.lastSeenAnnouncementCount = this.game.announcements.length;
+    // NOTE: do NOT advance lastSeenAnnouncementCount here. The caller advances
+    // it once the decision cycle terminates successfully — otherwise retried
+    // attempts would not see the FSM's rejection announcements in their input.
     const newAnnouncements = this.game.announcements
       .slice(sliceStart)
       .filter((a) => a.audience === 'both' || a.audience === this.color);
@@ -121,7 +126,10 @@ export class BotDriver {
         const result = handleCommit(this.game, this.color, {
           from: action.from, to: action.to, promotion: action.promotion,
         });
-        if (result.kind === 'applied') return { kind: 'done' };
+        if (result.kind === 'applied') {
+          finalizeIfEnded(this.game, result.announcements);
+          return { kind: 'done' };
+        }
         if (result.kind === 'announce') {
           const text = result.announcements[0]!.text;
           if (text === 'wont_help' || text === 'illegal_move'