fix(hls): isolate per-run lifecycle and use final-output byte accounting

- Give every Start its own run context, WaitGroup (including the queue
  producer), supervisor done channel and snapshots of the plan, request
  headers, HTTP client and merge target; Pause/Close wait for all run
  goroutines, including a merge in flight, before returning
- Build the HTTP client in Resolve/Start before workers launch instead of
  lazily inside do(), which raced between concurrent segment downloads
- Reject task edits while a run is active instead of mutating shared state
- Reset counters per run and seed them from the completed-segment journal;
  count only stored output bytes as progress, never discarded retry bytes
- Report Res.Size only when every segment is unencrypted with a known
  length; ciphertext sums overstate the final output, indeterminate plans
  rely on the engine's TotalDownloaded backfill at completion

internal/protocol/hls/fetcher_test.go

@@ -94,6 +94,15 @@ func mustRun(t *testing.T, f *Fetcher) {
 	}
 }
 
+func statsOf(t *testing.T, f *Fetcher) Stats {
+	t.Helper()
+	s, ok := f.Stats().Snapshot.(*Stats)
+	if !ok {
+		t.Fatalf("unexpected stats snapshot type %T", f.Stats().Snapshot)
+	}
+	return *s
+}
+
 func readOutput(t *testing.T, f *Fetcher) []byte {
 	t.Helper()
 	data, err := os.ReadFile(f.meta.SingleFilepath())
@@ -254,10 +263,10 @@ func TestFetcherE2E_AES128KeyRotation(t *testing.T) {
 
 	f := newTestFetcher(t, testConfig())
 	mustResolve(t, f, server.URL+"/video.m3u8", "")
+	// Ciphertext sizes overstate the final output after decryption, so an
+	// encrypted plan must report an indeterminate size.
 	if f.meta.Res.Size != 0 {
-		// Encrypted segment sizes are probed as ciphertext length, decryption
-		// shrinks them, so an all-or-nothing probe may still report a size.
-		t.Logf("prefetched size: %d", f.meta.Res.Size)
+		t.Errorf("encrypted plan should report size 0, got %d", f.meta.Res.Size)
 	}
 	mustRun(t, f)
 
@@ -345,10 +354,11 @@ func TestFetcherE2E_PauseResume(t *testing.T) {
 	if err := f.Pause(); err != nil {
 		t.Fatal(err)
 	}
-	if f.doneCount.Load() == 0 {
+	doneBefore := statsOf(t, f).SegmentsDone
+	if doneBefore == 0 {
 		t.Fatal("expected some segments to complete before pause")
 	}
-	if f.doneCount.Load() == total {
+	if doneBefore == total {
 		t.Fatal("all segments finished before pause, test is not exercising resume")
 	}
 
@@ -409,7 +419,7 @@ func TestFetcherE2E_StoreRestoreResume(t *testing.T) {
 	if err := f.Pause(); err != nil {
 		t.Fatal(err)
 	}
-	doneBefore := f.doneCount.Load()
+	doneBefore := statsOf(t, f).SegmentsDone
 	if doneBefore == 0 {
 		t.Fatal("expected some segments to finish before simulated restart")
 	}
@@ -450,8 +460,8 @@ func TestFetcherE2E_StoreRestoreResume(t *testing.T) {
 	if err := rf.Wait(); err != nil {
 		t.Fatal(err)
 	}
-	if rf.doneCount.Load() != total {
-		t.Errorf("want %d done, got %d", total, rf.doneCount.Load())
+	if done := statsOf(t, rf).SegmentsDone; done != total {
+		t.Errorf("want %d done, got %d", total, done)
 	}
 	var want []byte
 	for i := 0; i < total; i++ {

internal/protocol/hls/helper.go

@@ -13,6 +13,7 @@ import (
 	"time"
 
 	"github.com/GopeedLab/gopeed/internal/httpclient"
+	"github.com/GopeedLab/gopeed/pkg/base"
 )
 
 const defaultUserAgent = "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/116.0.0.0 Safari/537.36"
@@ -25,8 +26,16 @@ func (f *Fetcher) timeout() time.Duration {
 
 // buildClient builds an HTTP client honoring the task proxy and TLS settings.
 // The client has no total timeout on purpose: large segments over slow links
-// must not be aborted; body stalls are handled by stallReader instead.
+// must not be aborted; body stalls are handled by stallReader instead. It is
+// only called while the fetcher is quiescent (Resolve/Start), never from
+// inside running worker goroutines.
 func (f *Fetcher) buildClient() *http.Client {
+	var proxy *base.RequestProxy
+	skipVerify := false
+	if req := f.meta.Req; req != nil {
+		proxy = req.Proxy
+		skipVerify = req.SkipVerifyCert
+	}
 	jar, _ := cookiejar.New(nil)
 	client, err := httpclient.NewClient(httpclient.Options{
 		Client: httpclient.ClientOptions{
@@ -36,9 +45,9 @@ func (f *Fetcher) buildClient() *http.Client {
 			DialContext: (&net.Dialer{
 				Timeout: f.timeout(),
 			}).DialContext,
-			Proxy: f.Ctl.GetProxy(f.meta.Req.Proxy),
+			Proxy: f.Ctl.GetProxy(proxy),
 			TLSClientConfig: &tls.Config{
-				InsecureSkipVerify: f.meta.Req.SkipVerifyCert,
+				InsecureSkipVerify: skipVerify,
 			},
 			TLSHandshakeTimeout: f.timeout(),
 		},
@@ -54,14 +63,14 @@ func (f *Fetcher) buildClient() *http.Client {
 }
 
 // buildRequest builds a request with task extra headers, the default user
-// agent and an optional byte range.
-func (f *Fetcher) buildRequest(ctx context.Context, method, u string, body io.Reader, byterange *ByteRange) (*http.Request, error) {
+// agent and an optional byte range. extra may be nil.
+func buildRequest(ctx context.Context, extra *ReqExtra, method, u string, body io.Reader, byterange *ByteRange) (*http.Request, error) {
 	req, err := http.NewRequestWithContext(ctx, method, u, body)
 	if err != nil {
 		return nil, err
 	}
-	if f.extra != nil {
-		for key, value := range f.extra.Header {
+	if extra != nil {
+		for key, value := range extra.Header {
 			req.Header.Set(key, value)
 		}
 	}