fix: propagate input stream errors through ndJsonStream (#111)

* fix: propagate input stream errors through ndJsonStream

The readable stream returned by ndJsonStream used try/finally, which
swallowed errors from the underlying input stream. When the input
errored (e.g. a child process crash), the readable stream would close
cleanly instead of erroring, causing the Connection to treat it as a
normal shutdown rather than propagating the error to pending requests.

Changed to try/catch/finally so that input stream errors are forwarded
via controller.error(), allowing Connection.#receive() to capture the
error and reject all pending requests with the original error message.

Added two tests:
- Verifies ndJsonStream propagates immediate input stream errors
- Verifies pending requests are rejected when input stream errors

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

* Fix lockfile

---------

Co-authored-by: Mistral Vibe <vibe@mistral.ai>
Co-authored-by: Ben Brandt <benjamin.j.brandt@gmail.com>

Author: 3 people

src/acp.test.ts

@@ -1013,6 +1013,49 @@ describe("Connection", () => {
     }
   }
 
+  it("propagates input stream errors through ndJsonStream", async () => {
+    const inputStream = new ReadableStream<Uint8Array>({
+      start(controller) {
+        // Simulate a process crash after partial data
+        controller.error(new Error("process exited with code 1"));
+      },
+    });
+    const outputStream = new WritableStream<Uint8Array>();
+
+    const connection = new ClientSideConnection(
+      () => new MinimalTestClient(),
+      ndJsonStream(outputStream, inputStream),
+    );
+
+    await expect(connection.closed).resolves.toBeUndefined();
+    expect(connection.signal.aborted).toBe(true);
+  });
+
+  it("rejects pending requests when input stream errors via ndJsonStream", async () => {
+    let errorController!: ReadableStreamDefaultController<Uint8Array>;
+
+    const inputStream = new ReadableStream<Uint8Array>({
+      start(controller) {
+        errorController = controller;
+      },
+    });
+    const outputStream = new WritableStream<Uint8Array>();
+
+    const connection = new ClientSideConnection(
+      () => new MinimalTestClient(),
+      ndJsonStream(outputStream, inputStream),
+    );
+
+    const requestPromise = connection.newSession({
+      cwd: "/test",
+      mcpServers: [],
+    });
+
+    errorController.error(new Error("process exited with code 1"));
+
+    await expect(requestPromise).rejects.toThrow("process exited with code 1");
+  });
+
   it("rejects pending requests when the stream errors", async () => {
     let readableController!: ReadableStreamDefaultController<AnyMessage>;
 

src/stream.ts

@@ -63,10 +63,13 @@ export function ndJsonStream(
             }
           }
         }
+      } catch (err) {
+        controller.error(err);
+        return;
       } finally {
         reader.releaseLock();
-        controller.close();
       }
+      controller.close();
     },
   });