fix(cursor): settle clean Connect terminal without HTTP EOF

src/adapters/cursor/live-transport.ts

@@ -753,6 +753,22 @@ class LiveCursorTransport implements CursorTransport {
     }
   }
 
+  /**
+   * A clean Connect END_STREAM owns the turn terminal even when Cursor keeps the
+   * HTTP body open or tears it down with an abort/reset immediately afterward.
+   * Stop client-side liveness work and classify that later transport close as
+   * expected without actively sending an RST_STREAM back to Cursor.
+   */
+  private markProtocolComplete(): void {
+    this.expectedClose = true;
+    this.clearPendingFinalize();
+    if (this.heartbeat) {
+      clearInterval(this.heartbeat);
+      this.heartbeat = undefined;
+    }
+    this.clearFirstFrameTimer();
+  }
+
   private startShellCleanup(): Promise<BackgroundShellTerminationReport> {
     return this.shellCleanup ??= terminateBackgroundShellsForSession(this.shellOwnerId);
   }
@@ -1000,7 +1016,38 @@ class LiveCursorTransport implements CursorTransport {
           framesReceived: this.framesReceived,
           elapsedMs: Date.now() - this.turnStartedAt,
         } : { framesReceived: this.framesReceived, elapsedMs: Date.now() - this.turnStartedAt });
-        if (endError) failAndClear(endError);
+        if (endError) {
+          failAndClear(endError);
+          return;
+        }
+        // Connect's clean END_STREAM envelope is the protocol terminal. Cursor's RunSSE body can
+        // remain open after this frame (or close through an AbortError), so waiting for HTTP EOF
+        // strands an otherwise completed turn until the outer bridge stall watchdog fires.
+        //
+        // Earlier frames in this serialized frameWork chain have already run. Preserve their real
+        // turnEnded terminal when present; otherwise finalize the clean protocol end once so open
+        // tool calls still fail closed, a text-only turn receives its normal done event, and a
+        // drained client-tool turn does not lose the pending terminal when protocol cleanup clears
+        // its grace timer.
+        const hasPendingClientToolFinalization = this.pendingFinalize !== undefined;
+        if (
+          !this.expectedClose
+          && !state.terminated
+          && !this.emittedTerminal
+          && (
+            state.openToolCalls.size > 0
+            || this.sawAssistantText
+            || hasPendingClientToolFinalization
+          )
+        ) {
+          const terminal = hasPendingClientToolFinalization && state.openToolCalls.size === 0
+            ? finalizeAfterDrain(state)
+            : finalizeTurnEvents(state);
+          for (const event of terminal) push(event);
+        }
+        this.markProtocolComplete();
+        releaseBacklogLease();
+        settler.settleFinish();
         return;
       }
       await this.handleServerMessage(fromBinary(AgentServerMessageSchema, frame.payload), state, push);

structure/04_transports-and-sidecars.md

@@ -101,6 +101,14 @@ alone never opt a gateway in.
 and before the `/v1/*` guard. Unknown `/v1/*` paths return JSON 404 errors instead of falling through
 to GUI static serving.
 
+[Decision Log]
+- 목적과 의도: Complete Cursor turns at the protocol terminal instead of waiting for a separate HTTP-body EOF that may never arrive.
+- 기존 구현 및 제약 조건: Cursor can send turnEnded followed by a clean Connect END_STREAM envelope while RunSSE remains open or later closes through an abort-shaped transport error. The adapter logged the clean envelope but did not settle its terminal owner, so a completed-looking turn could remain open until the Responses stall watchdog.
+- 검토한 주요 대안: Shorten the global stall timeout; treat every later abort as success; settle only when the HTTP stream emits end; make the clean Connect envelope authoritative.
+- 선택한 방식: Process preceding frames in order, preserve an already-emitted terminal, run any already-armed drained client-tool finalizer before protocol cleanup clears its grace timer only while the call set is still drained, otherwise finalize once through the existing fail-closed tool-call logic, and settle the transport successfully on a clean Connect END_STREAM.
+- 다른 대안 대신 이 방식을 선택한 이유: The protocol envelope is upstream's explicit terminal signal. Timeout changes only hide the race, and globally swallowing aborts would mask genuine mid-turn cancellation.
+- 장점, 단점 및 영향: Completed Cursor responses no longer wait for the 300-second watchdog when the HTTP body stays open; incomplete tool calls still emit their existing truncation error, and error-bearing Connect terminals remain failures.
+
 A replayed compaction item carries an `encrypted_content` blob only its minting backend can decode,
 and the client replays it on every later turn. The proxy's own `ocx1:` envelopes are transparent
 base64, so they always lower to plain user messages. A native blob is relayed only when there is no

tests/cursor-eof-terminal.test.ts

@@ -3,6 +3,7 @@ import { create, toBinary } from "@bufbuild/protobuf";
 import { describe, expect, test } from "bun:test";
 import {
   AgentServerMessageSchema,
+  ExecServerMessageSchema,
   InteractionUpdateSchema,
   McpArgsSchema,
   McpToolCallSchema,
@@ -63,6 +64,29 @@ function toolCallStartedFrame(callId: string, toolName: string): Uint8Array {
   return encodeConnectFrame(toBinary(AgentServerMessageSchema, message));
 }
 
+function clientToolArgsFrame(callId: string, toolName: string, argText: string): Uint8Array {
+  const message = create(AgentServerMessageSchema, {
+    message: {
+      case: "execServerMessage",
+      value: create(ExecServerMessageSchema, {
+        id: 1,
+        execId: `exec-${callId}`,
+        message: {
+          case: "mcpArgs",
+          value: create(McpArgsSchema, {
+            name: toolName,
+            toolName,
+            toolCallId: callId,
+            providerIdentifier: PROVIDER,
+            args: { text: new TextEncoder().encode(JSON.stringify(argText)) },
+          }),
+        },
+      }),
+    },
+  });
+  return encodeConnectFrame(toBinary(AgentServerMessageSchema, message));
+}
+
 function turnEndedFrame(): Uint8Array {
   const message = create(AgentServerMessageSchema, {
     message: {
@@ -79,6 +103,10 @@ function emptyFrame(): Uint8Array {
   return encodeConnectFrame(toBinary(AgentServerMessageSchema, create(AgentServerMessageSchema, {})));
 }
 
+function cleanConnectEndFrame(): Uint8Array {
+  return encodeConnectFrame(new TextEncoder().encode("{}"), { endStream: true });
+}
+
 function runRequest(tools?: CursorRunRequest["tools"]): CursorRunRequest {
   return {
     modelId: "composer-2",
@@ -96,6 +124,17 @@ const APPLY_PATCH_TOOL = [{
   freeform: true,
 }] as unknown as CursorRunRequest["tools"];
 
+const ECHO_TOOL = [{
+  name: "echo_a",
+  description: "echo text",
+  parameters: { type: "object", properties: { text: { type: "string" } }, required: ["text"] },
+}] as unknown as CursorRunRequest["tools"];
+
+const ECHO_AND_APPLY_PATCH_TOOLS = [
+  ...(ECHO_TOOL ?? []),
+  ...(APPLY_PATCH_TOOL ?? []),
+] as CursorRunRequest["tools"];
+
 async function drain(baseUrl: string, request: CursorRunRequest): Promise<{
   messages: CursorServerMessage[];
   failure?: Error;
@@ -153,6 +192,80 @@ describe("Cursor clean-EOF terminal gate", () => {
     });
   });
 
+  test("clean Connect END_STREAM finishes before a held-open HTTP body (#2300)", async () => {
+    let fallback: ReturnType<typeof setTimeout> | undefined;
+    const startedAt = Date.now();
+    await withH2Server(stream => {
+      stream.on("error", () => {});
+      stream.respond({ ":status": 200, "content-type": "application/connect+proto" });
+      stream.write(Buffer.from(turnEndedFrame()));
+      stream.write(Buffer.from(cleanConnectEndFrame()));
+      // Model Cursor's observed shape: the protocol has ended, but the HTTP body has not. The
+      // fallback keeps the pre-fix test bounded; correct code returns well before it fires.
+      fallback = setTimeout(() => {
+        try { stream.end(); } catch { /* transport already closed */ }
+      }, 500);
+    }, async baseUrl => {
+      const { messages, failure } = await drain(baseUrl, runRequest());
+      expect(failure).toBeUndefined();
+      expect(messages.filter(message => message.type === "done")).toHaveLength(1);
+    });
+    if (fallback) clearTimeout(fallback);
+    expect(Date.now() - startedAt).toBeLessThan(450);
+  });
+
+  test("clean Connect END_STREAM wins over an immediate abort-shaped body teardown (#2300)", async () => {
+    await withH2Server(stream => {
+      stream.on("error", () => {});
+      stream.respond({ ":status": 200, "content-type": "application/connect+proto" });
+      stream.write(Buffer.from(turnEndedFrame()));
+      stream.write(Buffer.from(cleanConnectEndFrame()));
+      setImmediate(() => {
+        const abort = new Error("The operation was aborted");
+        abort.name = "AbortError";
+        stream.destroy(abort);
+      });
+    }, async baseUrl => {
+      const { messages, failure } = await drain(baseUrl, runRequest());
+      expect(failure).toBeUndefined();
+      expect(messages.filter(message => message.type === "done")).toHaveLength(1);
+      expect(messages.some(message => message.type === "error")).toBe(false);
+    });
+  });
+
+  test("clean Connect END_STREAM preserves a drained client-tool terminal before its grace timer", async () => {
+    await withH2Server(respondWith([
+      toolCallStartedFrame("call_client_1", "echo_a"),
+      clientToolArgsFrame("call_client_1", "echo_a", "A"),
+      cleanConnectEndFrame(),
+    ]), async baseUrl => {
+      const { messages, failure } = await drain(baseUrl, runRequest(ECHO_TOOL));
+
+      expect(failure).toBeUndefined();
+      expect(messages.filter(message => message.type === "tool_call_end")).toHaveLength(1);
+      expect(messages.filter(message => message.type === "done")).toHaveLength(1);
+      expect(messages.some(message => message.type === "error")).toBe(false);
+    });
+  });
+
+  test("clean Connect END_STREAM keeps a later open sibling fail-closed after a client-tool drain", async () => {
+    await withH2Server(respondWith([
+      toolCallStartedFrame("call_client_2", "echo_a"),
+      clientToolArgsFrame("call_client_2", "echo_a", "A"),
+      toolCallStartedFrame("call_open_2", "apply_patch"),
+      cleanConnectEndFrame(),
+    ]), async baseUrl => {
+      const { messages, failure } = await drain(baseUrl, runRequest(ECHO_AND_APPLY_PATCH_TOOLS));
+
+      expect(failure).toBeUndefined();
+      expect(messages.filter(message => message.type === "tool_call_end")).toHaveLength(1);
+      const terminal = messages.at(-1);
+      expect(terminal?.type).toBe("error");
+      expect((terminal as { message?: string }).message).toContain("call_open_2");
+      expect(messages.some(message => message.type === "done")).toBe(false);
+    });
+  });
+
   test("EOF with no open tool call keeps its existing graceful finish", async () => {
     await withH2Server(respondWith([emptyFrame()]), async baseUrl => {
       const { failure } = await drain(baseUrl, runRequest());