diff --git a/pkg/download/engine/cancellation_test.go b/pkg/download/engine/cancellation_test.go
new file mode 100644
index 00000000..39dff6ea
--- /dev/null
+++ b/pkg/download/engine/cancellation_test.go
@@ -0,0 +1,34 @@
+package engine
+
+import (
+	"github.com/dop251/goja"
+	"testing"
+	"time"
+)
+
+func TestCloseUnblocksPendingPromise(t *testing.T) {
+	e := NewEngine(nil)
+	entered := make(chan struct{})
+	_, err := e.runOnLoop(func(r *goja.Runtime) (goja.Value, error) {
+		return goja.Undefined(), r.Set("entered", func() { close(entered) })
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	done := make(chan error, 1)
+	go func() { _, err := e.RunString(`entered(); new Promise(()=>{});`); done <- err }()
+	select {
+	case <-entered:
+	case <-time.After(time.Second):
+		t.Fatal("script did not enter")
+	}
+	e.Close()
+	select {
+	case err := <-done:
+		if err == nil {
+			t.Fatal("closed execution returned success")
+		}
+	case <-time.After(300 * time.Millisecond):
+		t.Fatal("Engine.Close left the Promise waiter blocked")
+	}
+}
diff --git a/pkg/download/extension_cancellation_test.go b/pkg/download/extension_cancellation_test.go
new file mode 100644
index 00000000..1e832122
--- /dev/null
+++ b/pkg/download/extension_cancellation_test.go
@@ -0,0 +1,124 @@
+package download
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/GopeedLab/gopeed/internal/fetcher"
+	"github.com/GopeedLab/gopeed/pkg/base"
+)
+
+func installCancellationExtension(t *testing.T, d *Downloader, event, script string) {
+	t.Helper()
+	dir := t.TempDir()
+	manifest := fmt.Sprintf(`{"name":"cancel-%s","author":"test","title":"Cancel","version":"1.0.0","scripts":[{"event":%q,"match":{"urls":["*://example.com/*"]},"entry":"index.js"}]}`, event, event)
+	for name, body := range map[string]string{"manifest.json": manifest, "index.js": script} {
+		if err := os.WriteFile(filepath.Join(dir, name), []byte(body), 0600); err != nil {
+			t.Fatal(err)
+		}
+	}
+	if _, err := d.InstallExtensionByFolder(dir, true); err != nil {
+		t.Fatal(err)
+	}
+}
+func newCancellationDownloader(t *testing.T) *Downloader {
+	t.Helper()
+	d := NewDownloader(&DownloaderConfig{Storage: NewMemStorage(), StorageDir: t.TempDir(), TempDir: t.TempDir(), FetchManagers: []fetcher.FetcherManager{&generationTestManager{holdOpen: true}}})
+	if err := d.Setup(); err != nil {
+		t.Fatal(err)
+	}
+	return d
+}
+func TestResolveExtensionStopsOnShutdown(t *testing.T) {
+	entered, release := make(chan struct{}), make(chan struct{})
+	var once sync.Once
+	defer once.Do(func() { close(release) })
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		close(entered)
+		select {
+		case <-release:
+		case <-r.Context().Done():
+		}
+		w.Write([]byte("ok"))
+	}))
+	defer server.Close()
+	d := newCancellationDownloader(t)
+	defer d.Close()
+	installCancellationExtension(t, d, "onResolve", fmt.Sprintf(`gopeed.events.onResolve(async ctx=>{await fetch(%q);});`, server.URL))
+	done := make(chan error, 1)
+	go func() { _, err := d.Resolve(&base.Request{URL: "https://example.com/cancel"}); done <- err }()
+	select {
+	case <-entered:
+	case <-time.After(2 * time.Second):
+		t.Fatal("handler did not enter")
+	}
+	if err := d.Close(); err != nil {
+		t.Fatal(err)
+	}
+	select {
+	case err := <-done:
+		if !errors.Is(err, context.Canceled) {
+			t.Errorf("got %v, want cancellation", err)
+		}
+	case <-time.After(300 * time.Millisecond):
+		once.Do(func() { close(release) })
+		t.Fatal("shutdown did not cancel extension Resolve")
+	}
+}
+func TestOnErrorCancellationReleasesTaskAPIs(t *testing.T) {
+	entered, release := make(chan struct{}), make(chan struct{})
+	var once sync.Once
+	defer once.Do(func() { close(release) })
+	server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		close(entered)
+		select {
+		case <-release:
+		case <-r.Context().Done():
+		}
+		w.Write([]byte("ok"))
+	}))
+	defer server.Close()
+	d := newCancellationDownloader(t)
+	defer d.Close()
+	parent, cancel := context.WithCancel(d.backgroundCtx)
+	d.backgroundCtx = parent
+	defer cancel()
+	installCancellationExtension(t, d, "onError", fmt.Sprintf(`gopeed.events.onError(async ctx=>{await fetch(%q);});`, server.URL))
+	d.cfg.MaxRunning = 0
+	id, err := d.CreateDirect(&base.Request{URL: "generation://example.com/task"}, &base.Options{Path: t.TempDir()})
+	if err != nil {
+		t.Fatal(err)
+	}
+	task := d.GetTask(id)
+	task.statusLock.Lock()
+	task.Status = base.DownloadStatusRunning
+	task.statusLock.Unlock()
+	handled := make(chan struct{})
+	go func() { d.doOnError(task, errors.New("source failed")); close(handled) }()
+	select {
+	case <-entered:
+	case <-time.After(2 * time.Second):
+		t.Fatal("onError did not enter")
+	}
+	status, stats := make(chan struct{}), make(chan struct{})
+	go func() { d.RuntimeStatus(id); close(status) }()
+	go func() { d.Stats(id); close(stats) }()
+	cancel()
+	for name, ch := range map[string]<-chan struct{}{"onError": handled, "RuntimeStatus": status, "Stats": stats} {
+		select {
+		case <-ch:
+		case <-time.After(300 * time.Millisecond):
+			once.Do(func() { close(release) })
+			<-handled
+			t.Fatalf("%s stayed blocked after cancellation", name)
+		}
+	}
+}