From db847a98ee1d6428ffd491c2916713caa2665042 Mon Sep 17 00:00:00 2001
From: Aniruddha Adak <aniruddhaadak80@users.noreply.github.com>
Date: Sun, 4 Oct 2026 14:25:39 +0530
Subject: [PATCH] fix(server): release a refused download's body before
 reporting it

A download was refused when the computer's response carried no usable
content-length, but the body was left unread: the throw happened with the
stream still checked out. Nothing else ever reads it, and it can be as
large as the whole workspace download budget.

A computer reached through a proxy that re-chunks answers 200 with
Transfer-Encoding and no content-length, so every attempt left a transfer
running and a connection held until it was collected. A Bot retrying a
download turned one refusal into a slow leak rather than one clear error.

The refusal branch above already consumed its body via response.json(); this
brings the remaining refusal in line, and matches the release idiom already
used in provider-oauth.ts and voice/.

A cancel that fails must not replace the refusal the caller is told about,
so it is guarded and the ComputerUnavailableError still surfaces.
---
 CHANGELOG.md                         |  5 ++++
 server/src/computer/client.ts        |  4 ++++
 server/tests/computer-client.test.ts | 34 ++++++++++++++++++++++++++++
 3 files changed, 43 insertions(+)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7bb13829c..387997550 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,11 @@ Newest first. `Unreleased` is what is on `main` and not yet tagged.
 
 ## Unreleased
 
+- A file download refused because the computer's response carried no usable byte length now releases
+  the connection before reporting the refusal. The unread body could be as large as the whole
+  download budget, so a computer reached through a proxy that re-chunks left a transfer running and a
+  connection checked out of the pool on every attempt.
+
 ## 0.1.0
 
 **Before upgrading.** Six things change for an existing deployment:
diff --git a/server/src/computer/client.ts b/server/src/computer/client.ts
index 3fb61ec4e..74171d434 100644
--- a/server/src/computer/client.ts
+++ b/server/src/computer/client.ts
@@ -293,6 +293,10 @@ export function createComputerTransport(
     const bytes =
       length !== null && /^\d+$/.test(length) ? Number(length) : Number.NaN;
     if (!response.body || !Number.isSafeInteger(bytes) || bytes < 0) {
+      // Nothing else will ever read this body, so release it here rather than
+      // leaving the whole download budget checked out of the pool. A cancel that
+      // fails must not replace the refusal the caller is told about.
+      await response.body?.cancel().catch(() => undefined);
       throw new ComputerUnavailableError(
         "The assistant's computer returned an invalid file download.",
       );
diff --git a/server/tests/computer-client.test.ts b/server/tests/computer-client.test.ts
index 5e57f461e..7cb4fa2c2 100644
--- a/server/tests/computer-client.test.ts
+++ b/server/tests/computer-client.test.ts
@@ -73,6 +73,40 @@ describe("computer client", () => {
       );
     });
 
+    test("releases the connection it refuses to hand back", async () => {
+      let cancelled = false;
+      const body = new ReadableStream<Uint8Array>({
+        start(controller) {
+          controller.enqueue(Uint8Array.from([1, 2, 3]));
+        },
+        cancel() {
+          cancelled = true;
+        },
+      });
+      const client = clientWith(() => new Response(body));
+
+      await expect(client.download("x")).rejects.toThrow(
+        ComputerUnavailableError,
+      );
+      expect(cancelled).toBe(true);
+    });
+
+    test("still names the invalid download when releasing it fails", async () => {
+      const body = new ReadableStream<Uint8Array>({
+        start(controller) {
+          controller.enqueue(Uint8Array.from([1, 2, 3]));
+        },
+        cancel() {
+          throw new Error("socket already gone");
+        },
+      });
+      const client = clientWith(() => new Response(body));
+
+      await expect(client.download("x")).rejects.toThrow(
+        ComputerUnavailableError,
+      );
+    });
+
     test.each([
       [404, WorkspaceNotFoundError],
       [413, WorkspaceTooLargeError],