0.4.0 — fix queue-add race + per-item remove button (#10, #11)

server/engine.ts

@@ -284,6 +284,7 @@ function genericUnclearEvent(state: GameState): TurnEventSpec {
  */
 export function applyTurnResult(state: GameState, result: TurnResult): GameState {
   const next: GameState = JSON.parse(JSON.stringify(state));
+  next.version = (state.version ?? 0) + 1; // every mutation is a new revision
   const actingTurn = state.turn; // this action resolves the current turn
   next.turn = state.turn + 1; // then we advance to the next turn to play
   next.date = isDateLike(result.date) ? result.date : addDays(state.date, 2);
@@ -325,15 +326,34 @@ export function applyTurnResult(state: GameState, result: TurnResult): GameState
 /**
  * Immutably queue one item onto a round: append it to `pending` and return a new
  * state. This never advances the turn or the date — that only happens when a
- * round is committed via runTurn. Exported so the append-without-advance behavior
- * is unit-testable, and reused by the server's /action and /diplomacy routes.
+ * round is committed via runTurn. Bumps `version` (a new revision, so stale SSE
+ * snapshots can never clobber it client-side). Exported so the append-without-
+ * advance behavior is unit-testable, and reused by the /action and /diplomacy
+ * routes.
  */
 export function queueRoundItem(state: GameState, item: RoundItem): GameState {
   const next: GameState = JSON.parse(JSON.stringify(state));
+  next.version = (state.version ?? 0) + 1;
   next.pending.push(item);
   return next;
 }
 
+/**
+ * Immutably remove one item from the pending round by index and return a new
+ * state (bumping `version`). Returns `null` when the index is missing or not a
+ * valid, in-bounds integer position, so the route can answer 400 without
+ * mutating anything. Reused by the server's /queue/remove route.
+ */
+export function removeRoundItem(state: GameState, index: number | undefined): GameState | null {
+  if (index === undefined || !Number.isInteger(index) || index < 0 || index >= state.pending.length) {
+    return null;
+  }
+  const next: GameState = JSON.parse(JSON.stringify(state));
+  next.version = (state.version ?? 0) + 1;
+  next.pending.splice(index, 1);
+  return next;
+}
+
 /**
  * Run one turn end-to-end against the (injectable) LLM: build prompts, call the
  * model ONCE over the whole pending batch, parse/validate, retry once with a