fix(cursor): catch EOF terminal budget overflow

src/adapters/cursor/live-transport.ts

@@ -1129,7 +1129,7 @@ class LiveCursorTransport implements CursorTransport {
         }
         releaseBacklogLease();
         settler.settleFinish();
-      }, (err) => {
+      }).catch((err) => {
         failAndClear(err instanceof Error ? err : new Error(String(err)));
       });
     };

tests/cursor-hardening.test.ts

@@ -623,6 +623,60 @@ describe("Cursor live transport unexpected EOF", () => {
     expect(seenSessionId).toBe("cursor_from_gjc_session");
   });
 
+  test("settles as a failure when clean EOF synthesis exceeds the transport budget", async () => {
+    const textFrame = encodeConnectFrame(toBinary(AgentServerMessageSchema, create(AgentServerMessageSchema, {
+      message: {
+        case: "interactionUpdate",
+        value: create(InteractionUpdateSchema, {
+          message: {
+            case: "textDelta",
+            value: create(TextDeltaUpdateSchema, { text: "x" }),
+          },
+        }),
+      },
+    })));
+    const connectEnd = encodeConnectFrame(new TextEncoder().encode("{}"), {
+      flags: CONNECT_FLAG_END_STREAM,
+    });
+
+    await withDiscoveryServer(stream => {
+      stream.respond({ ":status": 200, "content-type": "application/connect+proto" });
+      stream.end(Buffer.from(new Uint8Array([
+        ...Array.from({ length: 37 }, () => [...textFrame]).flat(),
+        ...connectEnd,
+      ])));
+    }, async baseUrl => {
+      const budget = createTestTranslatorBudget({ maxTurnBytes: 1_000 });
+      const transport = createLiveCursorTransport({
+        provider: { adapter: "cursor", baseUrl, apiKey: "test-token" },
+        translatorBudget: budget,
+        firstFrameTimeoutMs: 2_000,
+      });
+      const iterator = transport.run({
+        modelId: "composer-2",
+        conversationId: "cursor_clean_eof_budget_test",
+        system: [],
+        messages: [{ role: "user", content: "hello" }],
+      })[Symbol.asyncIterator]();
+      let failure: Error | undefined;
+      try {
+        expect(await iterator.next()).toMatchObject({ value: { type: "text" } });
+        await Bun.sleep(20);
+        while (!(await iterator.next()).done) {}
+      } catch (err) {
+        failure = err instanceof Error ? err : new Error(String(err));
+      } finally {
+        await transport.close?.();
+      }
+
+      expect(failure).toMatchObject({
+        name: "TranslatorBudgetExceededError",
+        code: "translation_buffer_limit",
+      });
+      expect(budget.snapshot().currentBytes).toBe(0);
+    });
+  });
+
   test("synthesizes done after createPlanRequestQuery text on clean Connect EOF", async () => {
     const planFrame = encodeConnectFrame(toBinary(AgentServerMessageSchema, create(AgentServerMessageSchema, {
       message: {