fix: 优化客户端错误提示和校验诊断信息

2026-07-21 03:02:42 +00:00
parent 1c8ec37d2b
commit d9e32c6cea
14 changed files with 1739 additions and 627 deletions
@@ -25,16 +25,32 @@
 #include <openssl/err.h>
 #endif

-UpdaterLogic::UpdaterLogic(QObject* parent)
-    : QObject(parent)
-{
-    m_serverAddr = ConfigHelper::instance().getValue("Server", "api_base_url");
-}
+UpdaterLogic::UpdaterLogic(QObject* parent)
+    : QObject(parent)
+{
+    m_serverAddr = ConfigHelper::instance().getValue("Server", "api_base_url");
+}
+
+namespace {
+QString serverDetailMessage(const QJsonObject& response)
+{
+    const QJsonValue detail = response.value(QStringLiteral("detail"));
+    if (detail.isObject()) {
+        const QJsonObject obj = detail.toObject();
+        const QString msg = obj.value(QStringLiteral("msg")).toString();
+        if (!msg.isEmpty()) return msg;
+        const QString error = obj.value(QStringLiteral("error")).toString();
+        if (!error.isEmpty()) return error;
+    }
+    return detail.toString();
+}
+}

 void UpdaterLogic::getManifest(const QString& appId, const QString& channel, const QString& targetVer, int versionId)
 {
    // Manifest 由服务端按版本动态生成，描述目标版本包含哪些文件以及每个文件的 SHA256。
    // Updater 先拿到 Manifest，再请求下载 URL，最后按 Manifest 校验本地文件。
+    m_error.clear();
    QString url = m_serverAddr + "/api/v1/update/manifest";
    QJsonObject body;
    body["app_id"] = appId;
@@ -42,7 +58,7 @@ void UpdaterLogic::getManifest(const QString& appId, const QString& channel, con
    body["version"] = targetVer;
    body["version_id"] = versionId;

-    m_http.postRequest(url, body, [this](int code, const QJsonObject& resp)
+    m_http.postRequest(url, body, [this, appId, channel, targetVer, versionId](int code, const QJsonObject& resp)
        {
            qDebug() << "Manifest API returned code:" << code;
            m_manifest = QJsonObject();
@@ -68,61 +84,82 @@ void UpdaterLogic::getManifest(const QString& appId, const QString& channel, con
                        m_fileItems.append(fi);
                    }
                }
-                else
-                {
-                    qDebug() << "Manifest response missing fields";
-                }
-            }
-            else
-            {
-                qDebug() << "Failed to get manifest";
-            }
-            emit fetchUrlFinished();
-        });
-}
+                else
+                {
+                    qDebug() << "Manifest response missing fields";
+                    m_error = QCoreApplication::translate("UpdaterLogic",
+                        "Target version manifest response is incomplete. Stage: download target manifest. App: %1, channel: %2, version: %3, version id: %4.")
+                        .arg(appId, channel, targetVer, QString::number(versionId));
+                }
+            }
+            else
+            {
+                qDebug() << "Failed to get manifest";
+                const QString detail = serverDetailMessage(resp);
+                m_error = QCoreApplication::translate("UpdaterLogic",
+                    "Cannot download target version manifest. Stage: download target manifest. HTTP status: %1. App: %2, channel: %3, version: %4, version id: %5.%6")
+                    .arg(QString::number(code), appId, channel, targetVer, QString::number(versionId),
+                         detail.isEmpty() ? QString() : QCoreApplication::translate("UpdaterLogic", "\nServer message: %1").arg(detail));
+            }
+            emit fetchUrlFinished();
+        });
+}

 bool UpdaterLogic::verifySignature(const QByteArray& payload, const QString& signatureBase64, const QString& publicKeyPath) const
 {
-#ifndef HAVE_OPENSSL
-    Q_UNUSED(payload);
-    Q_UNUSED(signatureBase64);
-    Q_UNUSED(publicKeyPath);
-    qDebug() << "OpenSSL not available, cannot verify manifest signature";
-    return false;
-#else
-    QFile keyFile(publicKeyPath);
-    if (!keyFile.open(QIODevice::ReadOnly))
-    {
-        qDebug() << "Cannot open public key file:" << publicKeyPath;
-        return false;
-    }
+#ifndef HAVE_OPENSSL
+    Q_UNUSED(payload);
+    Q_UNUSED(signatureBase64);
+    Q_UNUSED(publicKeyPath);
+    qDebug() << "OpenSSL not available, cannot verify manifest signature";
+    m_error = QCoreApplication::translate("UpdaterLogic",
+        "Cannot verify manifest signature because OpenSSL support is unavailable. Stage: manifest signature verification.");
+    return false;
+#else
+    QFile keyFile(publicKeyPath);
+    if (!keyFile.open(QIODevice::ReadOnly))
+    {
+        qDebug() << "Cannot open public key file:" << publicKeyPath;
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Cannot open manifest public key. Stage: manifest signature verification. Public key path: %1.")
+            .arg(publicKeyPath);
+        return false;
+    }

    QByteArray keyData = keyFile.readAll();
    keyFile.close();

    BIO* bio = BIO_new_mem_buf(keyData.constData(), keyData.size());
-    if (!bio)
-    {
-        qDebug() << "BIO_new_mem_buf failed";
-        return false;
-    }
+    if (!bio)
+    {
+        qDebug() << "BIO_new_mem_buf failed";
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Cannot parse manifest public key buffer. Stage: manifest signature verification. Public key path: %1.")
+            .arg(publicKeyPath);
+        return false;
+    }

    EVP_PKEY* pkey = PEM_read_bio_PUBKEY(bio, NULL, NULL, NULL);
    BIO_free(bio);
-    if (!pkey)
-    {
-        qDebug() << "PEM_read_bio_PUBKEY failed";
-        return false;
-    }
+    if (!pkey)
+    {
+        qDebug() << "PEM_read_bio_PUBKEY failed";
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Manifest public key is invalid. Stage: manifest signature verification. Public key path: %1.")
+            .arg(publicKeyPath);
+        return false;
+    }

    QByteArray signature = QByteArray::fromBase64(signatureBase64.toUtf8());
    EVP_MD_CTX* mdctx = EVP_MD_CTX_new();
-    if (!mdctx)
-    {
-        EVP_PKEY_free(pkey);
-        qDebug() << "EVP_MD_CTX_new failed";
-        return false;
-    }
+    if (!mdctx)
+    {
+        EVP_PKEY_free(pkey);
+        qDebug() << "EVP_MD_CTX_new failed";
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Cannot create OpenSSL verification context. Stage: manifest signature verification.");
+        return false;
+    }

    bool ok = false;
    if (EVP_DigestVerifyInit(mdctx, NULL, EVP_sha256(), NULL, pkey) == 1)
@@ -139,29 +176,35 @@ bool UpdaterLogic::verifySignature(const QByteArray& payload, const QString& sig
    EVP_MD_CTX_free(mdctx);
    EVP_PKEY_free(pkey);

-    if (!ok)
-    {
-        qDebug() << "Manifest signature verification failed";
-    }
-    return ok;
-#endif
-}
+    if (!ok)
+    {
+        qDebug() << "Manifest signature verification failed";
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Manifest RSA signature is invalid. Stage: manifest signature verification. This usually means the manifest was not signed by the matching server private key, the client public key is wrong, or the manifest content was changed.");
+    }
+    return ok;
+#endif
+}

 bool UpdaterLogic::verifyManifestSignature(const QString& publicKeyPath) const
 {
    // 验签用的是客户端随 SDK 分发的公钥。
    // 只要服务端私钥没有泄漏，客户端就能发现被篡改的 Manifest。
    if (m_manifest.isEmpty() || m_manifestText.isEmpty())
-    {
-        qDebug() << "No manifest available to verify";
-        return false;
-    }
+    {
+        qDebug() << "No manifest available to verify";
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "No manifest is available for signature verification. Stage: manifest signature verification. The target manifest may not have been downloaded successfully.");
+        return false;
+    }
    QString signature = m_manifest.value("signature").toString();
-    if (signature.isEmpty())
-    {
-        qDebug() << "Manifest signature empty";
-        return false;
-    }
+    if (signature.isEmpty())
+    {
+        qDebug() << "Manifest signature empty";
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "The manifest does not contain a signature. Stage: manifest signature verification.");
+        return false;
+    }

    QString path = publicKeyPath;
    if (!QFile::exists(path))
@@ -175,18 +218,29 @@ bool UpdaterLogic::saveManifestCache(const QString& cacheDir) const
 {
    // 启动后的完整性检查依赖本地 Manifest 缓存。
    // 升级成功后缓存签名清单，下一次离线启动也能校验当前版本文件。
-    if (m_manifest.isEmpty())
-        return false;
-
-    QDir dir(cacheDir);
-    if (!dir.exists() && !dir.mkpath("."))
-        return false;
+    if (m_manifest.isEmpty()) {
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Cannot save manifest cache because the target manifest is empty. Stage: save target manifest cache.");
+        return false;
+    }
+
+    QDir dir(cacheDir);
+    if (!dir.exists() && !dir.mkpath(".")) {
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Cannot create manifest cache directory. Stage: save target manifest cache. Directory: %1.")
+            .arg(cacheDir);
+        return false;
+    }

    QString version = m_manifest.value("version").toString();
-    QString filePath = cacheDir + "/manifest_" + version + ".json";
-    QFile file(filePath);
-    if (!file.open(QIODevice::WriteOnly | QIODevice::Truncate))
-        return false;
+    QString filePath = cacheDir + "/manifest_" + version + ".json";
+    QFile file(filePath);
+    if (!file.open(QIODevice::WriteOnly | QIODevice::Truncate)) {
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Cannot write manifest cache file. Stage: save target manifest cache. File: %1. Error: %2.")
+            .arg(filePath, file.errorString());
+        return false;
+    }

    QJsonObject wrapper;
    wrapper["manifest"] = m_manifest;
@@ -194,33 +248,48 @@ bool UpdaterLogic::saveManifestCache(const QString& cacheDir) const

    QJsonDocument doc(wrapper);
    file.write(doc.toJson(QJsonDocument::Indented));
-    file.close();
-    qDebug() << "Manifest cached to" << filePath;
-    return true;
-}
-
-bool UpdaterLogic::loadManifestCache(const QString& cacheDir, const QString& version)
-{
-    QString filePath = cacheDir + "/manifest_" + version + ".json";
-    QFile file(filePath);
-    if (!file.exists() || !file.open(QIODevice::ReadOnly))
-        return false;
+    file.close();
+    qDebug() << "Manifest cached to" << filePath;
+    m_error.clear();
+    return true;
+}
+
+bool UpdaterLogic::loadManifestCache(const QString& cacheDir, const QString& version)
+{
+    m_error.clear();
+    QString filePath = cacheDir + "/manifest_" + version + ".json";
+    QFile file(filePath);
+    if (!file.exists() || !file.open(QIODevice::ReadOnly)) {
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Cannot read cached signed manifest. Stage: read local manifest cache. Version: %1. File: %2. This cache is created after a version is installed successfully.")
+            .arg(version, filePath);
+        return false;
+    }

    QByteArray raw = file.readAll();
    file.close();
-    QJsonDocument doc = QJsonDocument::fromJson(raw);
-    if (!doc.isObject())
-        return false;
+    QJsonDocument doc = QJsonDocument::fromJson(raw);
+    if (!doc.isObject()) {
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Cached signed manifest is not valid JSON. Stage: read local manifest cache. Version: %1. File: %2.")
+            .arg(version, filePath);
+        return false;
+    }
+
+    QJsonObject wrapper = doc.object();
+    if (!wrapper.contains("manifest") || !wrapper.contains("manifest_text")) {
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Cached signed manifest is incomplete. Stage: read local manifest cache. Version: %1. File: %2.")
+            .arg(version, filePath);
+        return false;
+    }

-    QJsonObject wrapper = doc.object();
-    if (!wrapper.contains("manifest") || !wrapper.contains("manifest_text"))
-        return false;
-
-    m_manifest = wrapper["manifest"].toObject();
-    m_manifestText = wrapper["manifest_text"].toString();
-    qDebug() << "Loaded cached manifest" << version;
-    return true;
-}
+    m_manifest = wrapper["manifest"].toObject();
+    m_manifestText = wrapper["manifest_text"].toString();
+    qDebug() << "Loaded cached manifest" << version;
+    m_error.clear();
+    return true;
+}

 QByteArray UpdaterLogic::canonicalManifestBytes(const QJsonObject& manifest) const
 {
@@ -311,43 +380,63 @@ QStringList UpdaterLogic::obsoleteFilesComparedTo(const QJsonObject& oldManifest
    return obsolete;
 }

-bool UpdaterLogic::validateLocalFiles(const QString& stagingDir, const QString& installedDir) const
-{
-    if (m_manifest.isEmpty())
-        return false;
-
-    const QJsonArray files = m_manifest.value("files").toArray();
-    for (const auto& item : files)
+bool UpdaterLogic::validateLocalFiles(const QString& stagingDir, const QString& installedDir) const
+{
+    m_error.clear();
+    const QString stage = installedDir.isEmpty()
+        ? QCoreApplication::translate("UpdaterLogic", "installed version verification")
+        : QCoreApplication::translate("UpdaterLogic", "downloaded/staged file verification");
+    const QString version = m_manifest.value(QStringLiteral("version")).toString();
+    if (m_manifest.isEmpty()) {
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "No manifest is available. Stage: %1. The updater cannot know which files and hashes should be verified.")
+            .arg(stage);
+        return false;
+    }
+
+    const QJsonArray files = m_manifest.value("files").toArray();
+    for (const auto& item : files)
    {
        const QJsonObject fileObject = item.toObject();
-        const QString path = QDir::fromNativeSeparators(fileObject.value("path").toString());
-        const QString expectedSha = fileObject.value("sha256").toString();
-        if (!isSafeRelativePath(path))
-            return false;
-        if (isRuntimeProtectedPath(path)) {
-            qDebug() << "Runtime-protected manifest entry ignored:" << path;
-            continue;
+        const QString path = QDir::fromNativeSeparators(fileObject.value("path").toString());
+        const QString expectedSha = fileObject.value("sha256").toString();
+        if (!isSafeRelativePath(path)) {
+            m_error = QCoreApplication::translate("UpdaterLogic",
+                "Manifest contains an unsafe file path. Stage: %1. Version: %2. Path: %3.")
+                .arg(stage, version, path);
+            return false;
+        }
+        if (isRuntimeProtectedPath(path)) {
+            qDebug() << "Runtime-protected manifest entry ignored:" << path;
+            continue;
        }

        QString fullPath = QDir(stagingDir).filePath(path);
        if (!QFile::exists(fullPath) && !installedDir.isEmpty())
            fullPath = QDir(installedDir).filePath(path);

-        if (!QFile::exists(fullPath))
-        {
-            qDebug() << "Manifest file missing from staging and installation:" << path;
-            return false;
-        }
-        const QString actualSha = calcLocalFileSha256(fullPath);
-        if (actualSha.compare(expectedSha, Qt::CaseInsensitive) != 0)
-        {
-            qDebug() << "File hash mismatch:" << path << actualSha << expectedSha;
-            return false;
-        }
-    }
-    qDebug() << "Full manifest validation passed using staging plus installed files";
-    return true;
-}
+        if (!QFile::exists(fullPath))
+        {
+            qDebug() << "Manifest file missing from staging and installation:" << path;
+            m_error = QCoreApplication::translate("UpdaterLogic",
+                "A required file is missing. Stage: %1. Version: %2. Manifest path: %3. Checked path: %4. If this is a downloaded update, the file was not downloaded or staged correctly; if this is startup verification, the installed file may have been deleted.")
+                .arg(stage, version, path, fullPath);
+            return false;
+        }
+        const QString actualSha = calcLocalFileSha256(fullPath);
+        if (actualSha.compare(expectedSha, Qt::CaseInsensitive) != 0)
+        {
+            qDebug() << "File hash mismatch:" << path << actualSha << expectedSha;
+            m_error = QCoreApplication::translate("UpdaterLogic",
+                "File SHA-256 does not match the signed manifest. Stage: %1. Version: %2. Manifest path: %3. Local path: %4.\nExpected SHA-256: %5\nActual SHA-256: %6\nIf this happens during download, clear the update cache and retry. If this happens during startup or after installation, the local file differs from the published version.")
+                .arg(stage, version, path, fullPath, expectedSha, actualSha.isEmpty() ? QCoreApplication::translate("UpdaterLogic", "<cannot read file>") : actualSha);
+            return false;
+        }
+    }
+    qDebug() << "Full manifest validation passed using staging plus installed files";
+    m_error.clear();
+    return true;
+}

 bool UpdaterLogic::loadOfflinePackage(const QString& packagePath, const QString& stagingDir)
 {
@@ -395,9 +484,10 @@ bool UpdaterLogic::loadOfflinePackage(const QString& packagePath, const QString&
    return true;
 }

-void UpdaterLogic::getDownloadUrl(const QString& appId, const QString& channel, const QString& targetVer, int versionId)
-{
-    QString url = m_serverAddr + "/api/v1/update/download-url";
+void UpdaterLogic::getDownloadUrl(const QString& appId, const QString& channel, const QString& targetVer, int versionId)
+{
+    m_error.clear();
+    QString url = m_serverAddr + "/api/v1/update/download-url";
    QJsonObject body;
    body["app_id"] = appId;
    body["channel"] = channel;
@@ -407,7 +497,7 @@ void UpdaterLogic::getDownloadUrl(const QString& appId, const QString& channel,
    QJsonArray emptyFiles;
    body["files"] = emptyFiles;

-    m_http.postRequest(url, body, [this](int code, const QJsonObject& resp)
+    m_http.postRequest(url, body, [this, appId, channel, targetVer, versionId](int code, const QJsonObject& resp)
        {
            qDebug() << "Download URL API returned code:" << code;
            m_fileItems.clear();
@@ -427,13 +517,18 @@ void UpdaterLogic::getDownloadUrl(const QString& appId, const QString& channel,
                    qDebug() << "File info:" << fi.path << fi.url << fi.sha256;
                }
            }
-            else
-            {
-                qDebug() << "Failed to get download URL";
-            }
-            emit fetchUrlFinished();
-        });
-}
+            else
+            {
+                qDebug() << "Failed to get download URL";
+                const QString detail = serverDetailMessage(resp);
+                m_error = QCoreApplication::translate("UpdaterLogic",
+                    "Cannot get secure download URLs. Stage: request download URLs. HTTP status: %1. App: %2, channel: %3, version: %4, version id: %5.%6")
+                    .arg(QString::number(code), appId, channel, targetVer, QString::number(versionId),
+                         detail.isEmpty() ? QString() : QCoreApplication::translate("UpdaterLogic", "\nServer message: %1").arg(detail));
+            }
+            emit fetchUrlFinished();
+        });
+}


 QString UpdaterLogic::calcLocalFileSha256(const QString& filePath) const
@@ -454,13 +549,21 @@ QString UpdaterLogic::calcLocalFileSha256(const QString& filePath) const
 bool UpdaterLogic::downloadSingleFile(const QString& url, const QString& savePath,
                                      const QString& expectSha256, qint64 expectedSize,
                                      const QString& resumePartPath)
-{
-    const QString partPath = resumePartPath.isEmpty() ? savePath + ".part" : resumePartPath;
-    if (!QDir().mkpath(QFileInfo(partPath).path())) return false;
-    if (QFile::exists(savePath)
-        && calcLocalFileSha256(savePath).compare(expectSha256, Qt::CaseInsensitive) == 0)
-        return true;
-    QFile::remove(savePath);
+{
+    const QString partPath = resumePartPath.isEmpty() ? savePath + ".part" : resumePartPath;
+    const QString displayPath = m_currentDownloadPath.isEmpty() ? savePath : m_currentDownloadPath;
+    if (!QDir().mkpath(QFileInfo(partPath).path())) {
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Cannot create partial download directory. Stage: download file. File: %1. Partial file: %2.")
+            .arg(displayPath, partPath);
+        return false;
+    }
+    if (QFile::exists(savePath)
+        && calcLocalFileSha256(savePath).compare(expectSha256, Qt::CaseInsensitive) == 0) {
+        m_error.clear();
+        return true;
+    }
+    QFile::remove(savePath);

    for (int attempt = 0; attempt < 4; ++attempt)
    {
@@ -472,23 +575,37 @@ bool UpdaterLogic::downloadSingleFile(const QString& url, const QString& savePat
        }
        if (expectedSize >= 0 && existingSize == expectedSize && existingSize > 0)
        {
-            if (calcLocalFileSha256(partPath).compare(expectSha256, Qt::CaseInsensitive) == 0)
-            {
-                QFile::remove(savePath);
-                return QFile::rename(partPath, savePath);
-            }
-            QFile::remove(partPath);
-            existingSize = 0;
-        }
+            if (calcLocalFileSha256(partPath).compare(expectSha256, Qt::CaseInsensitive) == 0)
+            {
+                QFile::remove(savePath);
+                if (QFile::rename(partPath, savePath)) {
+                    m_error.clear();
+                    return true;
+                }
+                m_error = QCoreApplication::translate("UpdaterLogic",
+                    "Downloaded file passed SHA-256 verification, but cannot move it into the staging directory. Stage: download file. File: %1. From: %2. To: %3.")
+                    .arg(displayPath, partPath, savePath);
+                return false;
+            }
+            const QString actualSha = calcLocalFileSha256(partPath);
+            m_error = QCoreApplication::translate("UpdaterLogic",
+                "Cached partial file has the expected size but wrong SHA-256. Stage: resume download. File: %1.\nExpected SHA-256: %2\nActual SHA-256: %3\nThe partial cache will be deleted and downloaded again.")
+                .arg(displayPath, expectSha256, actualSha);
+            QFile::remove(partPath);
+            existingSize = 0;
+        }

        QFile partFile(partPath);
        const QIODevice::OpenMode mode = QIODevice::WriteOnly
            | (existingSize > 0 ? QIODevice::Append : QIODevice::Truncate);
-        if (!partFile.open(mode))
-        {
-            qDebug() << "Cannot open partial download:" << partPath;
-            return false;
-        }
+        if (!partFile.open(mode))
+        {
+            qDebug() << "Cannot open partial download:" << partPath;
+            m_error = QCoreApplication::translate("UpdaterLogic",
+                "Cannot open partial download file. Stage: download file. File: %1. Partial file: %2. Error: %3.")
+                .arg(displayPath, partPath, partFile.errorString());
+            return false;
+        }

        QNetworkAccessManager manager;
        manager.setProxy(QNetworkProxy::NoProxy);
@@ -533,27 +650,45 @@ bool UpdaterLogic::downloadSingleFile(const QString& url, const QString& savePat
        else if (networkOk && writeOk && (httpStatus == 200 || httpStatus == 206))
        {
            const qint64 actualSize = QFileInfo(partPath).size();
-            if ((expectedSize < 0 || actualSize == expectedSize)
-                && calcLocalFileSha256(partPath).compare(expectSha256, Qt::CaseInsensitive) == 0)
-            {
-                QFile::remove(savePath);
-                if (QFile::rename(partPath, savePath))
-                {
-                    qDebug() << "Download completed/resumed & sha pass:" << savePath;
-                    return true;
-                }
-            }
-            else if (expectedSize >= 0 && actualSize >= expectedSize)
-            {
-                qDebug() << "Completed partial file has invalid size or SHA; restart:" << savePath;
-                QFile::remove(partPath);
-            }
-        }
-        else
-        {
-            qDebug() << "Download attempt failed; partial file retained:" << attempt + 1
-                     << savePath << httpStatus << networkError << "bytes" << QFileInfo(partPath).size();
-        }
+            if ((expectedSize < 0 || actualSize == expectedSize)
+                && calcLocalFileSha256(partPath).compare(expectSha256, Qt::CaseInsensitive) == 0)
+            {
+                QFile::remove(savePath);
+                if (QFile::rename(partPath, savePath))
+                {
+                    qDebug() << "Download completed/resumed & sha pass:" << savePath;
+                    m_error.clear();
+                    return true;
+                }
+                m_error = QCoreApplication::translate("UpdaterLogic",
+                    "Downloaded file passed SHA-256 verification, but cannot move it into the staging directory. Stage: download file. File: %1. From: %2. To: %3.")
+                    .arg(displayPath, partPath, savePath);
+                return false;
+            }
+            else if (expectedSize >= 0 && actualSize >= expectedSize)
+            {
+                qDebug() << "Completed partial file has invalid size or SHA; restart:" << savePath;
+                const QString actualSha = calcLocalFileSha256(partPath);
+                m_error = QCoreApplication::translate("UpdaterLogic",
+                    "Downloaded file does not match the signed manifest. Stage: download file. File: %1. HTTP status: %2.\nExpected size: %3 bytes\nActual size: %4 bytes\nExpected SHA-256: %5\nActual SHA-256: %6\nThe partial cache will be deleted and downloaded again.")
+                    .arg(displayPath, QString::number(httpStatus), QString::number(expectedSize), QString::number(actualSize),
+                         expectSha256, actualSha.isEmpty() ? QCoreApplication::translate("UpdaterLogic", "<cannot read file>") : actualSha);
+                QFile::remove(partPath);
+            }
+            else {
+                m_error = QCoreApplication::translate("UpdaterLogic",
+                    "Downloaded file is incomplete. Stage: download file. File: %1. HTTP status: %2. Expected size: %3 bytes, current size: %4 bytes.")
+                    .arg(displayPath, QString::number(httpStatus), QString::number(expectedSize), QString::number(actualSize));
+            }
+        }
+        else
+        {
+            qDebug() << "Download attempt failed; partial file retained:" << attempt + 1
+                     << savePath << httpStatus << networkError << "bytes" << QFileInfo(partPath).size();
+            m_error = QCoreApplication::translate("UpdaterLogic",
+                "Download request failed. Stage: download file. File: %1. Attempt: %2/4. HTTP status: %3. Network error: %4. Partial file: %5.")
+                .arg(displayPath, QString::number(attempt + 1), QString::number(httpStatus), networkError, partPath);
+        }

        if (attempt < 3)
        {
@@ -566,9 +701,14 @@ bool UpdaterLogic::downloadSingleFile(const QString& url, const QString& savePat
                QThread::msleep(50);
            }
        }
-    }
-    return false;
-}
+    }
+    if (m_error.isEmpty()) {
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "File download failed after retries. Stage: download file. File: %1.")
+            .arg(displayPath);
+    }
+    return false;
+}

 bool UpdaterLogic::isRuntimeProtectedPath(const QString& path) const
 {
@@ -632,20 +772,31 @@ qint64 UpdaterLogic::estimateAdditionalDiskBytes(const QString& targetDir,
    return required + reserve;
 }

-bool UpdaterLogic::downloadAllFiles(const QString& tempDir, const QString& targetDir)
-{
-    if (m_fileItems.isEmpty())
-    {
-        m_downloadAllOk = false;
-        return false;
-    }
-
-    QDir stagingDir(tempDir);
-    if (!FileHelper::createDir(tempDir))
-        return false;
-    const QString resumeCacheDir = QDir(ConfigHelper::instance().updateRoot()).filePath("download_cache");
-    if (!FileHelper::createDir(resumeCacheDir))
-        return false;
+bool UpdaterLogic::downloadAllFiles(const QString& tempDir, const QString& targetDir)
+{
+    m_error.clear();
+    if (m_fileItems.isEmpty())
+    {
+        m_downloadAllOk = false;
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "The target version manifest contains no downloadable files. Stage: prepare downloads.");
+        return false;
+    }
+
+    QDir stagingDir(tempDir);
+    if (!FileHelper::createDir(tempDir)) {
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Cannot create update staging directory. Stage: prepare downloads. Directory: %1.")
+            .arg(tempDir);
+        return false;
+    }
+    const QString resumeCacheDir = QDir(ConfigHelper::instance().updateRoot()).filePath("download_cache");
+    if (!FileHelper::createDir(resumeCacheDir)) {
+        m_error = QCoreApplication::translate("UpdaterLogic",
+            "Cannot create download cache directory. Stage: prepare downloads. Directory: %1.")
+            .arg(resumeCacheDir);
+        return false;
+    }
    QSet<QString> activePartialNames;
    for (const auto& item : m_fileItems)
        activePartialNames.insert(item.sha256.toLower() + ".part");
@@ -671,12 +822,15 @@ bool UpdaterLogic::downloadAllFiles(const QString& tempDir, const QString& targe

    for (const auto& fi : m_fileItems)
    {
-        if (!isSafeRelativePath(fi.path))
-        {
-            qDebug() << "Unsafe relative path in manifest:" << fi.path;
-            m_downloadAllOk = false;
-            return false;
-        }
+        if (!isSafeRelativePath(fi.path))
+        {
+            qDebug() << "Unsafe relative path in manifest:" << fi.path;
+            m_downloadAllOk = false;
+            m_error = QCoreApplication::translate("UpdaterLogic",
+                "Manifest contains an unsafe file path. Stage: prepare file download. Path: %1.")
+                .arg(fi.path);
+            return false;
+        }

        const QString relativePath = QDir::fromNativeSeparators(fi.path);
        if (isRuntimeProtectedPath(relativePath)) {
@@ -693,12 +847,15 @@ bool UpdaterLogic::downloadAllFiles(const QString& tempDir, const QString& targe

        const QString tempFile = QDir(tempDir).filePath(relativePath);
        const QString parentDir = QFileInfo(tempFile).path();
-        if (!QDir().mkpath(parentDir))
-        {
-            qDebug() << "Cannot create staging subdirectory:" << parentDir;
-            m_downloadAllOk = false;
-            return false;
-        }
+        if (!QDir().mkpath(parentDir))
+        {
+            qDebug() << "Cannot create staging subdirectory:" << parentDir;
+            m_downloadAllOk = false;
+            m_error = QCoreApplication::translate("UpdaterLogic",
+                "Cannot create staging subdirectory. Stage: prepare file download. File: %1. Directory: %2.")
+                .arg(relativePath, parentDir);
+            return false;
+        }

        const QString resumePartPath = QDir(resumeCacheDir).filePath(fi.sha256.toLower() + ".part");
        m_currentDownloadPath = relativePath;
@@ -717,9 +874,10 @@ bool UpdaterLogic::downloadAllFiles(const QString& tempDir, const QString& targe
                              m_currentDownloadPath, speed);
    }

-    m_downloadAllOk = true;
-    return true;
-}
+    m_downloadAllOk = true;
+    m_error.clear();
+    return true;
+}

 void UpdaterLogic::reportDownloadResult(const QString& appId, const QString& channel,
                                             const QString& version, bool success)