From e1c362699c9a545b9db99130424f5f32d20723c4 Mon Sep 17 00:00:00 2001
From: Ariver <shanghai3168@gmail.com>
Date: Wed, 03 Jun 2026 18:18:40 +0800
Subject: [PATCH] Record Round 5 QA and harden model downloads

---
 privatevoice.src/internal/model/downloader.go |  123 +++++++++++++++++++++++++++++++++++++---
 1 files changed, 112 insertions(+), 11 deletions(-)

diff --git a/privatevoice.src/internal/model/downloader.go b/privatevoice.src/internal/model/downloader.go
index e56e2cb..f77c66d 100755
--- a/privatevoice.src/internal/model/downloader.go
+++ b/privatevoice.src/internal/model/downloader.go
@@ -1,12 +1,15 @@
 package model
 
 import (
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strconv"
+	"strings"
 	"time"
 
 	"voicesnap/internal/logger"
@@ -102,27 +105,84 @@
 }
 
 func downloadFile(url, destPath string, progress ProgressCallback) error {
-	resp, err := http.Get(url)
+	const maxAttempts = 6
+	var lastErr error
+	var lastPercent = -1.0
+
+	for attempt := 1; attempt <= maxAttempts; attempt++ {
+		downloaded := existingFileSize(destPath)
+		err := downloadFileAttempt(url, destPath, downloaded, &lastPercent, progress)
+		if err == nil {
+			return nil
+		}
+		if isNonRetryableDownloadError(err) {
+			return err
+		}
+		lastErr = err
+		logger.Info("Download attempt %d/%d failed: %v", attempt, maxAttempts, err)
+		if attempt < maxAttempts {
+			time.Sleep(time.Duration(attempt) * time.Second)
+		}
+	}
+
+	return fmt.Errorf("download failed after %d attempts: %w", maxAttempts, lastErr)
+}
+
+func downloadFileAttempt(url, destPath string, resumeFrom int64, lastPercent *float64, progress ProgressCallback) error {
+	req, err := http.NewRequest(http.MethodGet, url, nil)
+	if err != nil {
+		return nonRetryableDownloadError{err: err}
+	}
+	if resumeFrom > 0 {
+		req.Header.Set("Range", fmt.Sprintf("bytes=%d-", resumeFrom))
+	}
+
+	resp, err := http.DefaultClient.Do(req)
 	if err != nil {
 		return err
 	}
 	defer resp.Body.Close()
 
-	if resp.StatusCode != http.StatusOK {
-		return fmt.Errorf("HTTP %d: %s", resp.StatusCode, resp.Status)
+	appendMode := resumeFrom > 0 && resp.StatusCode == http.StatusPartialContent
+	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusPartialContent {
+		err := fmt.Errorf("HTTP %d: %s", resp.StatusCode, resp.Status)
+		if resp.StatusCode < http.StatusInternalServerError {
+			return nonRetryableDownloadError{err: err}
+		}
+		return err
+	}
+	if resumeFrom > 0 && resp.StatusCode == http.StatusOK {
+		logger.Info("Download server ignored Range request; restarting download")
+		resumeFrom = 0
+		appendMode = false
 	}
 
 	totalBytes := resp.ContentLength
-	out, err := os.Create(destPath)
+	if appendMode {
+		if total := parseContentRangeTotal(resp.Header.Get("Content-Range")); total > 0 {
+			totalBytes = total
+		} else if resp.ContentLength > 0 {
+			totalBytes = resumeFrom + resp.ContentLength
+		}
+	}
+
+	flag := os.O_CREATE | os.O_WRONLY
+	if appendMode {
+		flag |= os.O_APPEND
+	} else {
+		flag |= os.O_TRUNC
+	}
+	out, err := os.OpenFile(destPath, flag, 0644)
 	if err != nil {
 		return err
 	}
 	defer out.Close()
 
+	downloaded := resumeFrom
+	if !appendMode {
+		downloaded = 0
+	}
 	buf := make([]byte, 32*1024)
-	var downloaded int64
-	lastPercent := -1.0
-
 	for {
 		n, readErr := resp.Body.Read(buf)
 		if n > 0 {
@@ -133,21 +193,62 @@
 
 			if totalBytes > 0 && progress != nil {
 				pct := float64(downloaded) / float64(totalBytes) * 100
-				if pct-lastPercent >= 0.5 {
-					lastPercent = pct
+				if pct-*lastPercent >= 0.5 {
+					*lastPercent = pct
 					progress(pct, downloaded, totalBytes)
 				}
 			}
 		}
 		if readErr != nil {
 			if readErr == io.EOF {
-				break
+				if totalBytes > 0 && downloaded < totalBytes {
+					return fmt.Errorf("short download: got %d of %d bytes", downloaded, totalBytes)
+				}
+				return nil
 			}
 			return readErr
 		}
 	}
+}
 
-	return nil
+func existingFileSize(path string) int64 {
+	info, err := os.Stat(path)
+	if err != nil || info.IsDir() {
+		return 0
+	}
+	return info.Size()
+}
+
+func parseContentRangeTotal(value string) int64 {
+	if value == "" {
+		return 0
+	}
+	slash := strings.LastIndex(value, "/")
+	if slash < 0 || slash == len(value)-1 {
+		return 0
+	}
+	total, err := strconv.ParseInt(value[slash+1:], 10, 64)
+	if err != nil {
+		return 0
+	}
+	return total
+}
+
+type nonRetryableDownloadError struct {
+	err error
+}
+
+func (e nonRetryableDownloadError) Error() string {
+	return e.err.Error()
+}
+
+func (e nonRetryableDownloadError) Unwrap() error {
+	return e.err
+}
+
+func isNonRetryableDownloadError(err error) bool {
+	var target nonRetryableDownloadError
+	return errors.As(err, &target)
 }
 
 func extractArchive(archivePath, destDir string) error {

--
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