fix: recover session submissions and failed turn settlement

tests/turn-liveness.test.ts

@@ -11,8 +11,19 @@ import assert from "node:assert/strict";
 import { describe, it } from "node:test";
 import { beginTurn, endTurn, isTurnRunning } from "../src/server/turn-liveness.ts";
 import { subscribe, type ServerEvent } from "../src/core/events.ts";
+import { rememberTurnFailure, settledTurnResponse } from "../src/server/turn-runs.ts";
 
 describe("turn liveness registry", () => {
+	it("retains a late-attach failure notice until the next accepted begin", async () => {
+		const id = "chat_failure_notice_unit";
+		rememberTurnFailure(id, "The reply could not be saved.");
+		assert.match(await settledTurnResponse(id).text(), /The reply could not be saved\./);
+		assert.match(await settledTurnResponse(id).text(), /The reply could not be saved\./, "reading does not consume the notice");
+		assert.equal(beginTurn(id), true);
+		assert.doesNotMatch(await settledTurnResponse(id).text(), /"type":"error"/);
+		endTurn(id);
+	});
+
 	it("begin/end round trip; a second begin is rejected until the turn ends", () => {
 		const id = "chat_liveness_unit";
 		assert.equal(isTurnRunning(id), false, "initially idle");