internal/cli/fetch.go

@@ -679,13 +679,15 @@ func resolveManifestURL(inputURL string) (string, error) {
 	return parsed.JoinPath(defaultManifestName).String(), nil
 }
 
-// progressWriter wraps an io.Writer and reports progress to a channel.
+// progressWriter wraps an io.Writer and reports progress to a channel,
+// at most once per second and once more when the last byte is written.
 type progressWriter struct {
 	w            io.Writer
 	path         string
 	total        int64
 	written      int64
 	startTime    time.Time
+	lastProgress time.Time
 	progress     chan<- DownloadProgress
 }
 
@@ -693,7 +695,10 @@ func (pw *progressWriter) Write(p []byte) (int, error) {
 	n, err := pw.w.Write(p)
 
 	pw.written += int64(n)
-	if pw.progress != nil {
+
+	isLast := pw.written == pw.total
+	if pw.progress != nil &&
+		(isLast || time.Since(pw.lastProgress) >= time.Second) {
 		var (
 			bytesPerSec float64
 			eta         time.Duration
@@ -715,6 +720,8 @@ func (pw *progressWriter) Write(p []byte) (int, error) {
 			BytesPerSec: bytesPerSec,
 			ETA:         eta,
 		})
+
+		pw.lastProgress = time.Now()
 	}
 
 	return n, err
@@ -899,12 +906,15 @@ func saveResponse(
 	// Set up hash computation
 	h := sha256.New()
 
-	// Create progress-reporting writer that also computes hash
+	// Create progress-reporting writer that also computes hash. The first
+	// update waits a second, as gen's and check's do.
+	start := time.Now()
 	pw := &progressWriter{
 		w:            io.MultiWriter(out, h),
 		path:         localPath,
 		total:        totalBytes,
-		startTime: time.Now(),
+		startTime:    start,
+		lastProgress: start,
 		progress:     progress,
 	}
 

internal/cli/fetch_test.go

@@ -516,7 +516,7 @@ func TestManifestDownloadStopsAtLimit(t *testing.T) {
 func TestFetchProgress(t *testing.T) {
 	// Create source filesystem with a larger test file
 	sourceFs := afero.NewMemMapFs()
-	// Create content large enough to trigger multiple progress updates
+	// Content large enough that io.Copy writes it in at least four chunks
 	content := bytes.Repeat([]byte("x"), 100*1024) // 100KB
 	require.NoError(t, afero.WriteFile(sourceFs, "/large.txt", content, 0o644))
 
@@ -559,8 +559,11 @@ func TestFetchProgress(t *testing.T) {
 	}()
 
 	// Download
+	start := time.Now()
 	err = downloadFile(context.Background(), testClient(),
 		server.URL+"/large.txt", ".", "large.txt", files[0], progress)
+	elapsed := time.Since(start)
+
 	close(progress)
 	<-done
 
@@ -569,6 +572,12 @@ func TestFetchProgress(t *testing.T) {
 	// Verify we got progress updates
 	assert.NotEmpty(t, progressUpdates, "should have received progress updates")
 
+	// At most one update per second, plus the one reporting the file
+	// complete: a download that takes under a second sends two at most,
+	// however many chunks it writes.
+	assert.LessOrEqual(t, len(progressUpdates), 2+int(elapsed/time.Second),
+		"one progress update per second at most, plus the last")
+
 	// Verify final progress shows complete
 	if len(progressUpdates) > 0 {
 		last := progressUpdates[len(progressUpdates)-1]