Release files when HTTP downloads are canceled (#6567)

* fix(server): close canceled HTTP download streams

* test(server): verify canceled downloads release real file descriptors

Exercise the reported HTTP cancellation path without replacing shared Node methods, and include download regressions in the standard integration suite.

Co-authored-by: 见安 <73627805+Mar-garet@users.noreply.github.com>

* test(server): detect canceled download leaks through symlinked paths

Compare descriptor targets with the resolved file path and exercise a symlinked download directory so the regression cannot pass by missing the open file.

---------

Co-authored-by: 见安 <73627805+Mar-garet@users.noreply.github.com>
Co-authored-by: paseo-bot[bot] <266920839+paseo-bot[bot]@users.noreply.github.com>

packages/server/package.json

@@ -89,7 +89,7 @@
     "speech:transcribe:local": "tsx scripts/transcribe-local-wav.ts",
     "test": "npm run test:unit && npm run test:integration",
     "test:unit": "vitest run --fileParallelism --exclude \"**/*.e2e.test.ts\"",
-    "test:integration": "vitest run --maxWorkers=1 src/server/daemon-e2e/cli-logs-follow.e2e.test.ts src/server/creation/creation.e2e.test.ts src/server/daemon-e2e/terminal-workspace-sdk.e2e.test.ts src/server/daemon-e2e/models.e2e.test.ts src/server/daemon-e2e/live-preferences.e2e.test.ts src/server/agent/model-catalog.e2e.test.ts src/server/plugins/plugin-paseo-api.e2e.test.ts && vitest run --maxWorkers=1 src/server/session.create-agent-worktree-autoarchive.e2e.test.ts -t \"creates a worktree and auto-archives both\" && vitest run --maxWorkers=1 src/server/agent/providers/opencode-bridge.local.e2e.test.ts -t \"versioned runtime\"",
+    "test:integration": "vitest run --maxWorkers=1 src/server/daemon-e2e/file-download.e2e.test.ts src/server/daemon-e2e/cli-logs-follow.e2e.test.ts src/server/creation/creation.e2e.test.ts src/server/daemon-e2e/terminal-workspace-sdk.e2e.test.ts src/server/daemon-e2e/models.e2e.test.ts src/server/daemon-e2e/live-preferences.e2e.test.ts src/server/agent/model-catalog.e2e.test.ts src/server/plugins/plugin-paseo-api.e2e.test.ts && vitest run --maxWorkers=1 src/server/session.create-agent-worktree-autoarchive.e2e.test.ts -t \"creates a worktree and auto-archives both\" && vitest run --maxWorkers=1 src/server/agent/providers/opencode-bridge.local.e2e.test.ts -t \"versioned runtime\"",
     "test:hub-cli-contract": "vitest run --maxWorkers=1 src/server/hub/hub-cli-contract.test.ts",
     "test:integration:all": "npm run test:e2e",
     "test:integration:real": "vitest run real.e2e.test.ts",

packages/server/src/server/bootstrap.ts

@@ -832,6 +832,9 @@ export async function createPaseoDaemon(
     try {
       fileHandle = await open(entry.absolutePath, DOWNLOAD_OPEN_FLAGS);
       const fileStats = await fileHandle.stat();
+      if (res.destroyed) {
+        return;
+      }
       if (!fileStats.isFile()) {
         res.status(404).json({ error: "File not found" });
         return;
@@ -843,6 +846,7 @@ export async function createPaseoDaemon(
 
       const stream = fileHandle.createReadStream();
       fileHandle = null;
+      res.once("close", () => stream.destroy());
       stream.on("error", (err) => {
         logger.error({ err }, "Failed to stream download");
         if (!res.headersSent) {

packages/server/src/server/daemon-e2e/file-download.e2e.test.ts

@@ -1,5 +1,15 @@
 import { describe, test, expect, beforeEach, afterEach } from "vitest";
-import { mkdtempSync, writeFileSync, rmSync } from "fs";
+import {
+  mkdtempSync,
+  writeFileSync,
+  rmSync,
+  readdirSync,
+  readlinkSync,
+  realpathSync,
+  symlinkSync,
+} from "fs";
+import { once } from "node:events";
+import { get } from "node:http";
 import { tmpdir } from "os";
 import path from "path";
 import { createDaemonTestContext, type DaemonTestContext } from "../test-utils/index.js";
@@ -8,6 +18,41 @@ function tmpCwd(): string {
   return mkdtempSync(path.join(tmpdir(), "daemon-e2e-"));
 }
 
+// Linux exposes the real open descriptors without replacing file or HTTP methods.
+function openDownloadDescriptors(filePath: string): string[] {
+  const realFilePath = realpathSync(filePath);
+  return readdirSync("/proc/self/fd").filter((fd) => {
+    try {
+      return readlinkSync(`/proc/self/fd/${fd}`) === realFilePath;
+    } catch (error) {
+      // A descriptor can close between listing it and reading its link.
+      if ((error as NodeJS.ErrnoException).code === "ENOENT") return false;
+      throw error;
+    }
+  });
+}
+
+async function expectDownloadClosed(filePath: string): Promise<void> {
+  await expect.poll(() => openDownloadDescriptors(filePath)).toEqual([]);
+}
+
+async function cancelDownloadAfterFirstChunk(url: string): Promise<void> {
+  const request = get(url);
+  try {
+    const [response] = await once(request, "response");
+    expect(response.statusCode).toBe(200);
+    const [chunk] = await once(response, "data");
+    expect(chunk.length).toBeGreaterThan(0);
+    expect(chunk.length).toBeLessThan(64 * 1024 * 1024);
+    const closed = once(response, "close");
+    response.destroy();
+    request.destroy();
+    await closed;
+  } finally {
+    request.destroy();
+  }
+}
+
 // Use gpt-5.4-mini with low thinking preset for faster test execution
 const CODEX_TEST_MODEL = "gpt-5.4-mini";
 const CODEX_TEST_THINKING_OPTION_ID = "low";
@@ -24,6 +69,39 @@ describe("daemon E2E", () => {
   }, 60000);
 
   describe("file download tokens", () => {
+    test.skipIf(process.platform !== "linux")(
+      "releases file descriptors after repeated HTTP download cancellations",
+      async () => {
+        const directory = tmpCwd();
+        const cwd = path.join(directory, "linked-files");
+        symlinkSync(mkdtempSync(path.join(directory, "files-")), cwd, "dir");
+        const filePath = path.join(cwd, "large.bin");
+        const fileSize = 64 * 1024 * 1024;
+        writeFileSync(filePath, Buffer.alloc(fileSize));
+        try {
+          const completedToken = await ctx.client.requestDownloadToken(cwd, "large.bin");
+          expect(completedToken.error).toBeNull();
+          const completed = await fetch(
+            `http://127.0.0.1:${ctx.daemon.port}/api/files/download?token=${completedToken.token}`,
+          );
+          expect(completed.status).toBe(200);
+          expect((await completed.arrayBuffer()).byteLength).toBe(fileSize);
+          await expectDownloadClosed(filePath);
+
+          for (let attempt = 0; attempt < 3; attempt++) {
+            const token = await ctx.client.requestDownloadToken(cwd, "large.bin");
+            expect(token.error).toBeNull();
+            await cancelDownloadAfterFirstChunk(
+              `http://127.0.0.1:${ctx.daemon.port}/api/files/download?token=${token.token}`,
+            );
+            await expectDownloadClosed(filePath);
+          }
+        } finally {
+          rmSync(directory, { recursive: true, force: true });
+        }
+      },
+    );
+
     test.each([
       { fileName: "download.txt", disposition: 'attachment; filename="download.txt"' },
       {