diff --git a/gui/CMakeLists.txt b/gui/CMakeLists.txt
index ef7c314..aeddb77 100644
--- a/gui/CMakeLists.txt
+++ b/gui/CMakeLists.txt
@@ -24,6 +24,11 @@ add_library(velox-gui-lib STATIC
     src/models/DownloadTableModel.cpp
     src/models/DownloadFilterProxy.cpp
     src/widgets/ProgressDelegate.cpp
+    src/widgets/SegmentBarsWidget.cpp
+    src/widgets/SpeedGraphWidget.cpp
+    src/dialogs/AddUrlDialog.cpp
+    src/dialogs/FileInfoDialog.cpp
+    src/dialogs/ProgressDialog.cpp
     src/mainwindow/CategoryPanel.cpp
     src/mainwindow/MainWindow.cpp
 )
diff --git a/gui/src/dialogs/AddUrlDialog.cpp b/gui/src/dialogs/AddUrlDialog.cpp
new file mode 100644
index 0000000..89c9b38
--- /dev/null
+++ b/gui/src/dialogs/AddUrlDialog.cpp
@@ -0,0 +1,58 @@
+#include "dialogs/AddUrlDialog.hpp"
+
+#include <QClipboard>
+#include <QDialogButtonBox>
+#include <QGuiApplication>
+#include <QLabel>
+#include <QLineEdit>
+#include <QPushButton>
+#include <QUrl>
+#include <QVBoxLayout>
+
+namespace velox::gui {
+namespace {
+
+QString clipboardUrlOrEmpty() {
+    const QString text = QGuiApplication::clipboard()->text().trimmed();
+    const QUrl url(text);
+    if (url.isValid() &&
+        (url.scheme() == QLatin1String("http") || url.scheme() == QLatin1String("https"))) {
+        return text;
+    }
+    return {};
+}
+
+}  // namespace
+
+AddUrlDialog::AddUrlDialog(QWidget *parent)
+    : QDialog(parent), urlEdit_(new QLineEdit(this)), buttons_(new QDialogButtonBox(this)) {
+    setWindowTitle(tr("Add URL"));
+
+    auto *layout = new QVBoxLayout(this);
+    layout->addWidget(new QLabel(tr("Enter the URL to download:"), this));
+    urlEdit_->setPlaceholderText(tr("https://example.com/file.iso"));
+    urlEdit_->setText(clipboardUrlOrEmpty());
+    urlEdit_->selectAll();
+    layout->addWidget(urlEdit_);
+
+    buttons_->setStandardButtons(QDialogButtonBox::Ok | QDialogButtonBox::Cancel);
+    layout->addWidget(buttons_);
+    connect(buttons_, &QDialogButtonBox::accepted, this, &QDialog::accept);
+    connect(buttons_, &QDialogButtonBox::rejected, this, &QDialog::reject);
+
+    const auto updateOkEnabled = [this] {
+        const QUrl u(urlEdit_->text().trimmed());
+        buttons_->button(QDialogButtonBox::Ok)
+            ->setEnabled(u.isValid() && !u.scheme().isEmpty() && !u.host().isEmpty());
+    };
+    connect(urlEdit_, &QLineEdit::textChanged, this, updateOkEnabled);
+    updateOkEnabled();
+
+    resize(480, sizeHint().height());
+}
+
+QString AddUrlDialog::url() const {
+    return urlEdit_->text().trimmed();
+}
+
+}  // namespace velox::gui
diff --git a/gui/src/dialogs/AddUrlDialog.hpp b/gui/src/dialogs/AddUrlDialog.hpp
new file mode 100644
index 0000000..46c940c
--- /dev/null
+++ b/gui/src/dialogs/AddUrlDialog.hpp
@@ -0,0 +1,30 @@
+// "Add URL" — the first of the paired Add-URL / File-Info dialogs. Lane GUI.
+//
+// docs/06-risks-and-spikes.md R2: pre-filling this from the clipboard on open is one of
+// the two *explicit* clipboard paths the GUI relies on (passive monitoring is best-effort
+// and not implemented yet). This dialog does nothing else — no probing, no saving; that is
+// FileInfoDialog's job once this returns a URL.
+
+#pragma once
+
+#include <QDialog>
+
+class QLineEdit;
+class QDialogButtonBox;
+
+namespace velox::gui {
+
+class AddUrlDialog : public QDialog {
+    Q_OBJECT
+
+  public:
+    explicit AddUrlDialog(QWidget *parent = nullptr);
+
+    QString url() const;
+
+  private:
+    QLineEdit *urlEdit_;
+    QDialogButtonBox *buttons_;
+};
+
+}  // namespace velox::gui
diff --git a/gui/src/dialogs/FileInfoDialog.cpp b/gui/src/dialogs/FileInfoDialog.cpp
new file mode 100644
index 0000000..7ce8b35
--- /dev/null
+++ b/gui/src/dialogs/FileInfoDialog.cpp
@@ -0,0 +1,268 @@
+#include "dialogs/FileInfoDialog.hpp"
+
+#include <QCheckBox>
+#include <QComboBox>
+#include <QFileDialog>
+#include <QFormLayout>
+#include <QHBoxLayout>
+#include <QJsonArray>
+#include <QLabel>
+#include <QLineEdit>
+#include <QLocale>
+#include <QMenu>
+#include <QPointer>
+#include <QPushButton>
+#include <QSpinBox>
+#include <QToolButton>
+#include <QUrl>
+#include <QVBoxLayout>
+
+#include "rpc/RpcClient.hpp"
+
+namespace velox::gui {
+namespace {
+
+QString filenameFromUrl(const QString &url) {
+    const QString path = QUrl(url).path();
+    const QString name = path.section('/', -1);
+    return name.isEmpty() ? QStringLiteral("download") : name;
+}
+
+struct BufferChoice {
+    const char *label;
+    qint64 bytes;
+};
+constexpr BufferChoice kBufferChoices[] = {
+    {"256 KiB", 256 * 1024},      {"512 KiB", 512 * 1024},    {"1 MiB", 1024 * 1024},
+    {"2 MiB", 2 * 1024 * 1024},   {"4 MiB", 4 * 1024 * 1024}, {"8 MiB", 8 * 1024 * 1024},
+    {"16 MiB", 16 * 1024 * 1024},
+};
+
+}  // namespace
+
+FileInfoDialog::FileInfoDialog(rpc::RpcClient *client, QString url, QJsonArray categories,
+                               QJsonArray queues, QWidget *parent)
+    : QDialog(parent),
+      client_(client),
+      url_(std::move(url)),
+      filenameEdit_(new QLineEdit(this)),
+      saveDirEdit_(new QLineEdit(this)),
+      categoryCombo_(new QComboBox(this)),
+      sizeLabel_(new QLabel(tr("Probing…"), this)),
+      resumeLabel_(new QLabel(tr("Probing…"), this)),
+      descriptionEdit_(new QLineEdit(this)),
+      connectionsSpin_(new QSpinBox(this)),
+      bufferCombo_(new QComboBox(this)),
+      addToQueueButton_(new QToolButton(this)),
+      errorLabel_(new QLabel(this)) {
+    setWindowTitle(tr("Download File Info"));
+
+    filenameEdit_->setText(filenameFromUrl(url_));
+    connect(filenameEdit_, &QLineEdit::textEdited, this, [this] { filenameEditedByUser_ = true; });
+    connect(saveDirEdit_, &QLineEdit::textEdited, this, [this] { saveDirEditedByUser_ = true; });
+
+    populateCategories(categories);
+    populateQueueMenu(queues);
+
+    connectionsSpin_->setRange(1, 32);
+    connectionsSpin_->setValue(8);
+
+    for (const auto &choice : kBufferChoices) {
+        bufferCombo_->addItem(QString::fromLatin1(choice.label), QVariant::fromValue(choice.bytes));
+    }
+    bufferCombo_->setCurrentIndex(4);  // 4 MiB, matching the spec's mockup default
+
+    auto *browse = new QPushButton(tr("Browse…"), this);
+    connect(browse, &QPushButton::clicked, this, &FileInfoDialog::browseSaveDir);
+    auto *saveDirRow = new QWidget(this);
+    auto *saveDirLayout = new QHBoxLayout(saveDirRow);
+    saveDirLayout->setContentsMargins(0, 0, 0, 0);
+    saveDirLayout->addWidget(saveDirEdit_, 1);
+    saveDirLayout->addWidget(browse);
+
+    auto *sizeResumeRow = new QWidget(this);
+    auto *sizeResumeLayout = new QHBoxLayout(sizeResumeRow);
+    sizeResumeLayout->setContentsMargins(0, 0, 0, 0);
+    sizeResumeLayout->addWidget(sizeLabel_);
+    sizeResumeLayout->addSpacing(16);
+    sizeResumeLayout->addWidget(resumeLabel_);
+    sizeResumeLayout->addStretch();
+
+    auto *remember = new QCheckBox(tr("Remember for this file type"), this);
+    remember->setEnabled(false);  // not wired to settings yet — Options dialog isn't built
+
+    auto *form = new QFormLayout;
+    form->addRow(tr("File Name:"), filenameEdit_);
+    form->addRow(tr("Save As:"), saveDirRow);
+    form->addRow(tr("Category:"), categoryCombo_);
+    form->addRow(QString(), sizeResumeRow);
+    form->addRow(tr("Description:"), descriptionEdit_);
+    form->addRow(tr("Connections:"), connectionsSpin_);
+    form->addRow(tr("Buffer:"), bufferCombo_);
+    form->addRow(QString(), remember);
+
+    errorLabel_->setStyleSheet(QStringLiteral("color: #c0392b;"));
+    errorLabel_->setWordWrap(true);
+    errorLabel_->hide();
+
+    addToQueueButton_->setText(tr("Add to Queue"));
+    addToQueueButton_->setPopupMode(QToolButton::MenuButtonPopup);
+    auto *downloadNow = new QPushButton(tr("Download Now"), this);
+    downloadNow->setDefault(true);
+    auto *downloadLater = new QPushButton(tr("Download Later"), this);
+    auto *cancel = new QPushButton(tr("Cancel"), this);
+    connect(downloadNow, &QPushButton::clicked, this,
+            [this] { submit(QStringLiteral("now"), {}); });
+    connect(downloadLater, &QPushButton::clicked, this,
+            [this] { submit(QStringLiteral("later"), {}); });
+    connect(cancel, &QPushButton::clicked, this, &QDialog::reject);
+
+    auto *buttonRow = new QHBoxLayout;
+    buttonRow->addStretch();
+    buttonRow->addWidget(downloadNow);
+    buttonRow->addWidget(downloadLater);
+    buttonRow->addWidget(addToQueueButton_);
+    buttonRow->addWidget(cancel);
+
+    auto *outer = new QVBoxLayout(this);
+    outer->addLayout(form);
+    outer->addWidget(errorLabel_);
+    outer->addLayout(buttonRow);
+    resize(560, sizeHint().height());
+
+    QPointer<FileInfoDialog> self(this);
+    client_->call(QStringLiteral("download.probe"), QJsonObject{{"url", url_}},
+                  [self](const rpc::RpcReply &reply) {
+                      if (!self) {
+                          return;  // dialog closed before the probe answered
+                      }
+                      self->onProbeFinished(reply.ok(), reply.result.toObject());
+                  });
+}
+
+void FileInfoDialog::populateCategories(const QJsonArray &categories) {
+    categoryCombo_->addItem(tr("(Automatic)"), QString());
+    for (const QJsonValue &v : categories) {
+        const QJsonObject c = v.toObject();
+        categoryCombo_->addItem(c.value("name").toString(), c.value("categoryId").toString());
+    }
+}
+
+void FileInfoDialog::populateQueueMenu(const QJsonArray &queues) {
+    if (queues.isEmpty()) {
+        addToQueueButton_->setEnabled(false);
+        return;
+    }
+    auto *menu = new QMenu(addToQueueButton_);
+    for (const QJsonValue &v : queues) {
+        const QJsonObject q = v.toObject();
+        const QString queueId = q.value("queueId").toString();
+        menu->addAction(q.value("name").toString(), this,
+                        [this, queueId] { submit(QStringLiteral("queue"), queueId); });
+    }
+    addToQueueButton_->setMenu(menu);
+    connect(addToQueueButton_, &QToolButton::clicked, addToQueueButton_, &QToolButton::showMenu);
+}
+
+QString FileInfoDialog::selectedCategoryId() const {
+    return categoryCombo_->currentData().toString();
+}
+
+void FileInfoDialog::onProbeFinished(bool ok, const QJsonObject &result) {
+    if (!ok) {
+        sizeLabel_->setText(tr("Size: unknown"));
+        resumeLabel_->setText(tr("Resume capability: unknown"));
+        errorLabel_->setText(
+            tr("Could not probe this URL; you can still try to download it as entered."));
+        errorLabel_->show();
+        return;
+    }
+
+    if (!filenameEditedByUser_) {
+        const QString probed = result.value("filename").toString();
+        if (!probed.isEmpty()) {
+            filenameEdit_->setText(probed);
+        }
+    }
+    if (!saveDirEditedByUser_) {
+        const QString suggested = result.value("suggestedSaveDir").toString();
+        if (!suggested.isEmpty()) {
+            saveDirEdit_->setText(suggested);
+        }
+    }
+    const QJsonValue size = result.value("sizeBytes");
+    sizeLabel_->setText(tr("Size: %1")
+                            .arg(size.isDouble() ? QLocale().formattedDataSize(
+                                                       static_cast<qint64>(size.toDouble()), 2)
+                                                 : tr("unknown")));
+    resumeLabel_->setText(
+        tr("Resume capability: %1").arg(result.value("resumable").toBool() ? tr("Yes") : tr("No")));
+
+    const QString suggestedCategory = result.value("suggestedCategoryId").toString();
+    if (!suggestedCategory.isEmpty()) {
+        const int idx = categoryCombo_->findData(suggestedCategory);
+        if (idx >= 0) {
+            categoryCombo_->setCurrentIndex(idx);
+        }
+    }
+}
+
+void FileInfoDialog::browseSaveDir() {
+    const QString dir =
+        QFileDialog::getExistingDirectory(this, tr("Save As"), saveDirEdit_->text());
+    if (!dir.isEmpty()) {
+        saveDirEdit_->setText(dir);
+        saveDirEditedByUser_ = true;
+    }
+}
+
+void FileInfoDialog::submit(const QString &startMode, const QString &queueId) {
+    const QJsonObject spec = buildSpec(
+        url_, filenameEdit_->text().trimmed(), saveDirEdit_->text().trimmed(), selectedCategoryId(),
+        descriptionEdit_->text().trimmed(), connectionsSpin_->value(),
+        bufferCombo_->currentData().toLongLong(), startMode, queueId);
+
+    QPointer<FileInfoDialog> self(this);
+    client_->call(QStringLiteral("download.add"), spec, [self](const rpc::RpcReply &reply) {
+        if (!self) {
+            return;
+        }
+        if (reply.ok()) {
+            self->accept();
+            return;
+        }
+        self->errorLabel_->setText(tr("Could not add the download: %1").arg(reply.error.message));
+        self->errorLabel_->show();
+    });
+}
+
+QJsonObject FileInfoDialog::buildSpec(const QString &url, const QString &filename,
+                                      const QString &saveDir, const QString &categoryId,
+                                      const QString &description, int segments, qint64 bufferBytes,
+                                      const QString &startMode, const QString &queueId) {
+    QJsonObject spec{{"url", url}, {"startMode", startMode}};
+    if (!filename.isEmpty()) {
+        spec["filename"] = filename;
+    }
+    if (!saveDir.isEmpty()) {
+        spec["saveDir"] = saveDir;
+    }
+    if (!categoryId.isEmpty()) {
+        spec["categoryId"] = categoryId;
+    }
+    if (!description.isEmpty()) {
+        spec["description"] = description;
+    }
+    if (segments > 0) {
+        spec["segments"] = segments;
+    }
+    if (bufferBytes > 0) {
+        spec["bufferBytes"] = bufferBytes;
+    }
+    if (startMode == QLatin1String("queue") && !queueId.isEmpty()) {
+        spec["queueId"] = queueId;
+    }
+    return spec;
+}
+
+}  // namespace velox::gui
diff --git a/gui/src/dialogs/FileInfoDialog.hpp b/gui/src/dialogs/FileInfoDialog.hpp
new file mode 100644
index 0000000..da7a04f
--- /dev/null
+++ b/gui/src/dialogs/FileInfoDialog.hpp
@@ -0,0 +1,66 @@
+// "Download File Info" — IDM's signature dialog. Lane GUI.
+//
+// docs/03-gui-spec.md §2. Opens immediately with a spinner in Size/Resume capability;
+// download.probe runs async and never blocks the UI thread. Ends by calling download.add
+// itself (Download Now / Download Later / Add to Queue) so MainWindow only has to open it.
+
+#pragma once
+
+#include <QDialog>
+#include <QJsonArray>
+#include <QJsonObject>
+
+class QComboBox;
+class QLabel;
+class QLineEdit;
+class QSpinBox;
+class QToolButton;
+
+namespace velox::gui {
+namespace rpc {
+class RpcClient;
+}  // namespace rpc
+
+class FileInfoDialog : public QDialog {
+    Q_OBJECT
+
+  public:
+    FileInfoDialog(rpc::RpcClient *client, QString url, QJsonArray categories, QJsonArray queues,
+                   QWidget *parent = nullptr);
+
+    /// Pure: the DownloadSpec params for download.add, built from already-resolved values —
+    /// no widget access, so it is unit-testable on its own.
+    static QJsonObject buildSpec(const QString &url, const QString &filename,
+                                 const QString &saveDir, const QString &categoryId,
+                                 const QString &description, int segments, qint64 bufferBytes,
+                                 const QString &startMode, const QString &queueId);
+
+  private slots:
+    void onProbeFinished(bool ok, const QJsonObject &result);
+    void browseSaveDir();
+    void submit(const QString &startMode, const QString &queueId);
+
+  private:
+    void populateCategories(const QJsonArray &categories);
+    void populateQueueMenu(const QJsonArray &queues);
+    QString selectedCategoryId() const;
+
+    rpc::RpcClient *client_;
+    QString url_;
+
+    QLineEdit *filenameEdit_;
+    QLineEdit *saveDirEdit_;
+    QComboBox *categoryCombo_;
+    QLabel *sizeLabel_;
+    QLabel *resumeLabel_;
+    QLineEdit *descriptionEdit_;
+    QSpinBox *connectionsSpin_;
+    QComboBox *bufferCombo_;
+    QToolButton *addToQueueButton_;
+    QLabel *errorLabel_;
+
+    bool filenameEditedByUser_ = false;
+    bool saveDirEditedByUser_ = false;
+};
+
+}  // namespace velox::gui
diff --git a/gui/src/dialogs/ProgressDialog.cpp b/gui/src/dialogs/ProgressDialog.cpp
new file mode 100644
index 0000000..9cd25eb
--- /dev/null
+++ b/gui/src/dialogs/ProgressDialog.cpp
@@ -0,0 +1,274 @@
+#include "dialogs/ProgressDialog.hpp"
+
+#include <QCheckBox>
+#include <QComboBox>
+#include <QDesktopServices>
+#include <QDir>
+#include <QFormLayout>
+#include <QHBoxLayout>
+#include <QJsonArray>
+#include <QLabel>
+#include <QMessageBox>
+#include <QPointer>
+#include <QPushButton>
+#include <QUrl>
+#include <QVBoxLayout>
+
+#include "rpc/RpcClient.hpp"
+#include "util/Format.hpp"
+#include "widgets/SegmentBarsWidget.hpp"
+#include "widgets/SpeedGraphWidget.hpp"
+
+namespace velox::gui {
+namespace {
+
+enum OnCompletionAction { kDoNothing = 0, kOpenFile, kOpenFolder };
+
+bool isTerminal(const QString &state) {
+    return state == QLatin1String("complete") || state == QLatin1String("failed") ||
+           state == QLatin1String("cancelled");
+}
+
+QString stateText(const QString &state) {
+    static const QHash<QString, QString> kLabels = {
+        {QStringLiteral("queued"), ProgressDialog::tr("Queued")},
+        {QStringLiteral("connecting"), ProgressDialog::tr("Connecting…")},
+        {QStringLiteral("downloading"), ProgressDialog::tr("Receiving data…")},
+        {QStringLiteral("paused"), ProgressDialog::tr("Paused")},
+        {QStringLiteral("retry_wait"), ProgressDialog::tr("Waiting to retry…")},
+        {QStringLiteral("assembling"), ProgressDialog::tr("Assembling…")},
+        {QStringLiteral("verifying"), ProgressDialog::tr("Verifying…")},
+        {QStringLiteral("complete"), ProgressDialog::tr("Complete")},
+        {QStringLiteral("failed"), ProgressDialog::tr("Failed")},
+        {QStringLiteral("cancelled"), ProgressDialog::tr("Cancelled")},
+    };
+    return kLabels.value(state, state);
+}
+
+std::vector<SegmentInfo> segmentsFromDetail(const QJsonArray &detail) {
+    std::vector<SegmentInfo> out;
+    out.reserve(static_cast<std::size_t>(detail.size()));
+    for (const QJsonValue &v : detail) {
+        const QJsonObject s = v.toObject();
+        SegmentInfo info;
+        info.index = static_cast<qint64>(s.value("index").toDouble());
+        info.downloadedBytes = static_cast<qint64>(s.value("downloadedBytes").toDouble());
+        const qint64 start = static_cast<qint64>(s.value("startByte").toDouble());
+        const qint64 end = static_cast<qint64>(s.value("endByte").toDouble());
+        info.totalBytes = end >= start ? (end - start + 1) : -1;
+        info.speedBps = static_cast<qint64>(s.value("speedBps").toDouble());
+        info.state = s.value("state").toString();
+        out.push_back(info);
+    }
+    return out;
+}
+
+}  // namespace
+
+ProgressDialog::ProgressDialog(rpc::RpcClient *client, QString taskId, QWidget *parent)
+    : QDialog(parent),
+      client_(client),
+      taskId_(std::move(taskId)),
+      urlLabel_(new QLabel(this)),
+      statusLabel_(new QLabel(this)),
+      fileSizeLabel_(new QLabel(this)),
+      downloadedLabel_(new QLabel(this)),
+      rateLabel_(new QLabel(this)),
+      timeLeftLabel_(new QLabel(this)),
+      resumeLabel_(new QLabel(this)),
+      segmentsWidget_(new SegmentBarsWidget(this)),
+      speedGraph_(new SpeedGraphWidget(this)),
+      closeWhenDone_(new QCheckBox(tr("Close dialog when done"), this)),
+      onCompletion_(new QComboBox(this)),
+      pauseButton_(new QPushButton(tr("Pause"), this)),
+      cancelButton_(new QPushButton(tr("Cancel"), this)) {
+    setAttribute(Qt::WA_DeleteOnClose);
+    setWindowTitle(tr("Download Progress"));
+    resize(560, 480);
+
+    urlLabel_->setWordWrap(true);
+    urlLabel_->setTextInteractionFlags(Qt::TextSelectableByMouse);
+
+    auto *form = new QFormLayout;
+    form->addRow(tr("URL"), urlLabel_);
+    form->addRow(tr("Status"), statusLabel_);
+    form->addRow(tr("File size"), fileSizeLabel_);
+    form->addRow(tr("Downloaded"), downloadedLabel_);
+    form->addRow(tr("Transfer rate"), rateLabel_);
+    form->addRow(tr("Time left"), timeLeftLabel_);
+    form->addRow(tr("Resume capability"), resumeLabel_);
+
+    onCompletion_->addItem(tr("Do nothing"), kDoNothing);
+    onCompletion_->addItem(tr("Open file"), kOpenFile);
+    onCompletion_->addItem(tr("Open folder"), kOpenFolder);
+    // "Exit Velox" / "Shut down" wait on the tray + session integration (build order
+    // step 6) — offering them here with no backing action would be a fake affordance.
+
+    auto *bottomRow = new QHBoxLayout;
+    bottomRow->addWidget(closeWhenDone_);
+    bottomRow->addStretch();
+    bottomRow->addWidget(new QLabel(tr("On completion:"), this));
+    bottomRow->addWidget(onCompletion_);
+
+    auto *hideButton = new QPushButton(tr("Hide"), this);
+    connect(hideButton, &QPushButton::clicked, this, &QDialog::close);
+    connect(pauseButton_, &QPushButton::clicked, this, &ProgressDialog::togglePause);
+    connect(cancelButton_, &QPushButton::clicked, this, &ProgressDialog::cancelTask);
+
+    auto *actionRow = new QHBoxLayout;
+    actionRow->addStretch();
+    actionRow->addWidget(pauseButton_);
+    actionRow->addWidget(cancelButton_);
+    actionRow->addWidget(hideButton);
+
+    auto *layout = new QVBoxLayout(this);
+    layout->addLayout(form);
+    layout->addWidget(segmentsWidget_, 1);
+    layout->addWidget(speedGraph_);
+    layout->addLayout(bottomRow);
+    layout->addLayout(actionRow);
+
+    connect(client_, &rpc::RpcClient::taskProgress, this, &ProgressDialog::onTaskProgress);
+    connect(client_, &rpc::RpcClient::taskStateChanged, this, &ProgressDialog::onTaskState);
+
+    QPointer<ProgressDialog> self(this);
+    client_->call(QStringLiteral("download.get"), QJsonObject{{"taskId", taskId_}},
+                  [self](const rpc::RpcReply &reply) {
+                      if (!self || !reply.ok()) {
+                          return;
+                      }
+                      const QJsonObject result = reply.result.toObject();
+                      self->applySummary(result.value("summary").toObject());
+                      self->segments_ = segmentsFromDetail(result.value("segmentDetail").toArray());
+                      self->segmentsWidget_->setSegments(self->segments_);
+                  });
+}
+
+void ProgressDialog::applySummary(const QJsonObject &summary) {
+    if (summary.isEmpty()) {
+        return;
+    }
+    urlLabel_->setText(summary.value("url").toString());
+    filename_ = summary.value("filename").toString();
+    saveDir_ = summary.value("saveDir").toString();
+    if (!filename_.isEmpty()) {
+        setWindowTitle(filename_);
+    }
+    state_ = summary.value("state").toString();
+    const QJsonValue size = summary.value("sizeBytes");
+    sizeBytes_ = size.isDouble() ? static_cast<qint64>(size.toDouble()) : -1;
+    downloadedBytes_ = static_cast<qint64>(summary.value("downloadedBytes").toDouble());
+    speedBps_ = static_cast<qint64>(summary.value("speedBps").toDouble());
+    const QJsonValue eta = summary.value("etaSeconds");
+    etaSeconds_ = eta.isDouble() ? static_cast<qint64>(eta.toDouble()) : -1;
+    resumable_ = summary.value("resumable").toBool();
+    refreshLabels();
+}
+
+void ProgressDialog::refreshLabels() {
+    statusLabel_->setText(stateText(state_));
+    fileSizeLabel_->setText(fmt::bytes(sizeBytes_));
+    if (sizeBytes_ > 0) {
+        const double pct =
+            100.0 * static_cast<double>(downloadedBytes_) / static_cast<double>(sizeBytes_);
+        downloadedLabel_->setText(
+            tr("%1 (%2 %)").arg(fmt::bytes(downloadedBytes_)).arg(pct, 0, 'f', 2));
+    } else {
+        downloadedLabel_->setText(fmt::bytes(downloadedBytes_));
+    }
+    rateLabel_->setText(state_ == QLatin1String("downloading") ? fmt::rate(speedBps_) : QString());
+    timeLeftLabel_->setText(state_ == QLatin1String("downloading") ? fmt::eta(etaSeconds_)
+                                                                   : QString());
+    resumeLabel_->setText(resumable_ ? tr("Yes") : tr("No"));
+
+    const bool terminal = isTerminal(state_);
+    pauseButton_->setText(state_ == QLatin1String("paused") ? tr("Resume") : tr("Pause"));
+    pauseButton_->setEnabled(!terminal);
+    cancelButton_->setEnabled(!terminal);
+}
+
+void ProgressDialog::onTaskProgress(const QJsonArray &tasks) {
+    for (const QJsonValue &v : tasks) {
+        const QJsonObject t = v.toObject();
+        if (t.value("taskId").toString() != taskId_) {
+            continue;
+        }
+        downloadedBytes_ = static_cast<qint64>(t.value("downloadedBytes").toDouble());
+        speedBps_ = static_cast<qint64>(t.value("speedBps").toDouble());
+        const QJsonValue eta = t.value("etaSeconds");
+        etaSeconds_ = eta.isDouble() ? static_cast<qint64>(eta.toDouble()) : -1;
+        state_ = QStringLiteral("downloading");  // event.task.progress only fires while active
+
+        for (const QJsonValue &sv : t.value("segments").toArray()) {
+            const QJsonObject s = sv.toObject();
+            const qint64 idx = static_cast<qint64>(s.value("index").toDouble());
+            for (auto &seg : segments_) {
+                if (seg.index == idx) {
+                    seg.downloadedBytes =
+                        static_cast<qint64>(s.value("downloadedBytes").toDouble());
+                    seg.speedBps = static_cast<qint64>(s.value("speedBps").toDouble());
+                    seg.state = QStringLiteral("downloading");
+                    break;
+                }
+            }
+        }
+        segmentsWidget_->setSegments(segments_);
+        speedGraph_->addSample(speedBps_);
+        refreshLabels();
+        return;
+    }
+}
+
+void ProgressDialog::onTaskState(const QJsonObject &params) {
+    if (params.value("taskId").toString() != taskId_) {
+        return;
+    }
+    const QJsonObject summary = params.value("summary").toObject();
+    if (!summary.isEmpty()) {
+        applySummary(summary);
+    } else {
+        state_ = params.value("state").toString();
+        refreshLabels();
+    }
+    if (isTerminal(state_)) {
+        handleTerminalState();
+    }
+}
+
+void ProgressDialog::handleTerminalState() {
+    if (state_ == QLatin1String("complete") && !saveDir_.isEmpty() && !filename_.isEmpty()) {
+        const QString path = QDir(saveDir_).filePath(filename_);
+        switch (onCompletion_->currentData().toInt()) {
+            case kOpenFile:
+                QDesktopServices::openUrl(QUrl::fromLocalFile(path));
+                break;
+            case kOpenFolder:
+                QDesktopServices::openUrl(QUrl::fromLocalFile(saveDir_));
+                break;
+            default:
+                break;
+        }
+    }
+    if (closeWhenDone_->isChecked()) {
+        close();
+    }
+}
+
+void ProgressDialog::togglePause() {
+    const bool paused = state_ == QLatin1String("paused");
+    client_->call(
+        QString::fromLatin1(paused ? rpc::method::kDownloadResume : rpc::method::kDownloadPause),
+        QJsonObject{{"taskIds", QJsonArray{taskId_}}});
+}
+
+void ProgressDialog::cancelTask() {
+    if (QMessageBox::question(this, tr("Stop download"),
+                              tr("Stop this download? Partial data is kept.")) !=
+        QMessageBox::Yes) {
+        return;
+    }
+    client_->call(QString::fromLatin1(rpc::method::kDownloadCancel),
+                  QJsonObject{{"taskIds", QJsonArray{taskId_}}});
+}
+
+}  // namespace velox::gui
diff --git a/gui/src/dialogs/ProgressDialog.hpp b/gui/src/dialogs/ProgressDialog.hpp
new file mode 100644
index 0000000..538afd0
--- /dev/null
+++ b/gui/src/dialogs/ProgressDialog.hpp
@@ -0,0 +1,75 @@
+// The per-task download progress dialog. Lane GUI.
+//
+// docs/03-gui-spec.md §3. Non-modal (Qt::WA_DeleteOnClose, shown not exec()'d) so several
+// can be open at once and none of them block the main window. Driven entirely by the
+// events RpcClient already re-broadcasts — download.get is called exactly once, to seed
+// state for a dialog opened on a task that is already mid-transfer.
+
+#pragma once
+
+#include <QDialog>
+#include <QJsonArray>
+#include <QJsonObject>
+#include <vector>
+
+#include "widgets/SegmentBarsWidget.hpp"
+
+class QCheckBox;
+class QComboBox;
+class QLabel;
+class QPushButton;
+
+namespace velox::gui {
+
+class SegmentBarsWidget;
+class SpeedGraphWidget;
+namespace rpc {
+class RpcClient;
+}  // namespace rpc
+
+class ProgressDialog : public QDialog {
+    Q_OBJECT
+
+  public:
+    ProgressDialog(rpc::RpcClient *client, QString taskId, QWidget *parent = nullptr);
+
+  private slots:
+    void onTaskProgress(const QJsonArray &tasks);
+    void onTaskState(const QJsonObject &params);
+    void togglePause();
+    void cancelTask();
+
+  private:
+    void applySummary(const QJsonObject &summary);
+    void refreshLabels();
+    void handleTerminalState();
+
+    rpc::RpcClient *client_;
+    QString taskId_;
+
+    QLabel *urlLabel_;
+    QLabel *statusLabel_;
+    QLabel *fileSizeLabel_;
+    QLabel *downloadedLabel_;
+    QLabel *rateLabel_;
+    QLabel *timeLeftLabel_;
+    QLabel *resumeLabel_;
+    SegmentBarsWidget *segmentsWidget_;
+    SpeedGraphWidget *speedGraph_;
+    QCheckBox *closeWhenDone_;
+    QComboBox *onCompletion_;
+    QPushButton *pauseButton_;
+    QPushButton *cancelButton_;
+
+    QString state_;
+    QString saveDir_;
+    QString filename_;
+    qint64 sizeBytes_ = -1;
+    qint64 downloadedBytes_ = 0;
+    qint64 speedBps_ = 0;
+    qint64 etaSeconds_ = -1;
+    bool resumable_ = false;
+    std::vector<SegmentInfo> segments_;
+};
+
+}  // namespace velox::gui
diff --git a/gui/src/mainwindow/MainWindow.cpp b/gui/src/mainwindow/MainWindow.cpp
index c36ebf4..4c3722c 100644
--- a/gui/src/mainwindow/MainWindow.cpp
+++ b/gui/src/mainwindow/MainWindow.cpp
@@ -22,22 +22,18 @@
 #include <QVBoxLayout>
 #include <QWidget>
 
+#include "dialogs/AddUrlDialog.hpp"
+#include "dialogs/FileInfoDialog.hpp"
+#include "dialogs/ProgressDialog.hpp"
 #include "mainwindow/CategoryPanel.hpp"
 #include "models/DownloadTableModel.hpp"
 #include "rpc/RpcClient.hpp"
+#include "util/Format.hpp"
 #include "widgets/ProgressDelegate.hpp"
 
 namespace velox::gui {
 namespace {
 
-QString humanRate(qint64 bps) {
-    if (bps <= 0) {
-        return QStringLiteral("0 B/s");
-    }
-    return MainWindow::tr("%1/s").arg(
-        QLocale().formattedDataSize(bps, 1, QLocale::DataSizeIecFormat));
-}
-
 QString dotStyle(const QString &colour) {
     return QStringLiteral("color: %1; font-size: 14px;").arg(colour);
 }
@@ -70,6 +66,10 @@ MainWindow::MainWindow(rpc::RpcClient *client, QWidget *parent)
     view_->setSelectionMode(QAbstractItemView::ExtendedSelection);
     view_->setSortingEnabled(true);
     view_->setItemDelegateForColumn(DownloadTableModel::ColStatus, new ProgressDelegate(this));
+    view_->setContextMenuPolicy(Qt::CustomContextMenu);
+    connect(view_, &QWidget::customContextMenuRequested, this, &MainWindow::showTableContextMenu);
+    connect(view_, &QAbstractItemView::doubleClicked, this,
+            &MainWindow::openPropertiesForSelection);
     view_->header()->setSectionsMovable(true);
     view_->header()->setStretchLastSection(true);
 
@@ -141,7 +141,7 @@ MainWindow::~MainWindow() = default;
 void MainWindow::buildActions() {
     actAddUrl_ = new QAction(tr("Add &URL…"), this);
     actAddUrl_->setShortcut(QKeySequence(Qt::CTRL | Qt::Key_N));
-    actAddUrl_->setEnabled(false);  // wired up with the Add URL dialog (build order step 5)
+    connect(actAddUrl_, &QAction::triggered, this, &MainWindow::openAddUrlDialog);
 
     actResume_ = new QAction(tr("&Resume"), this);
     actResume_->setShortcut(QKeySequence(Qt::CTRL | Qt::Key_R));
@@ -163,6 +163,9 @@ void MainWindow::buildActions() {
 
     actPauseAll_ = new QAction(tr("Pause All"), this);
     connect(actPauseAll_, &QAction::triggered, this, &MainWindow::pauseAll);
+
+    actProperties_ = new QAction(tr("&Properties…"), this);
+    connect(actProperties_, &QAction::triggered, this, &MainWindow::openPropertiesForSelection);
 }
 
 void MainWindow::buildMenus() {
@@ -174,6 +177,7 @@ void MainWindow::buildMenus() {
     tasks->addAction(actStop_);
     tasks->addSeparator();
     tasks->addAction(actRemove_);
+    tasks->addAction(actProperties_);
     tasks->addSeparator();
     tasks->addAction(tr("E&xit"), QKeySequence::Quit, this, &QWidget::close);
 
@@ -237,7 +241,8 @@ void MainWindow::onConnectionState(rpc::ConnectionState state) {
                            : tr("The Velox service is not running. Downloads are unaffected; "
                                 "this list is read-only until it returns."));
     }
-    for (QAction *a : {actResume_, actPause_, actStop_, actRemove_, actResumeAll_, actPauseAll_}) {
+    for (QAction *a : {actResume_, actPause_, actStop_, actRemove_, actResumeAll_, actPauseAll_,
+                       actAddUrl_, actProperties_}) {
         a->setEnabled(online);
     }
 
@@ -249,16 +254,72 @@ void MainWindow::onConnectionState(rpc::ConnectionState state) {
 void MainWindow::fetchTree() {
     client_->call(QStringLiteral("category.list"), {}, [this](const rpc::RpcReply &reply) {
         if (reply.ok()) {
-            panel_->setCategories(reply.result.toObject().value("items").toArray());
+            categoriesCache_ = reply.result.toObject().value("items").toArray();
+            panel_->setCategories(categoriesCache_);
         }
     });
     client_->call(QStringLiteral("queue.list"), {}, [this](const rpc::RpcReply &reply) {
         if (reply.ok()) {
-            panel_->setQueues(reply.result.toObject().value("items").toArray());
+            queuesCache_ = reply.result.toObject().value("items").toArray();
+            panel_->setQueues(queuesCache_);
         }
     });
 }
 
+void MainWindow::openAddUrlDialog() {
+    AddUrlDialog dlg(this);
+    if (dlg.exec() != QDialog::Accepted) {
+        return;
+    }
+    const QString url = dlg.url();
+    if (url.isEmpty()) {
+        return;
+    }
+    // Non-modal: several File Info dialogs can be open at once (spec §2), and it must
+    // never block the main window while download.probe is in flight.
+    auto *info = new FileInfoDialog(client_, url, categoriesCache_, queuesCache_, this);
+    info->setAttribute(Qt::WA_DeleteOnClose);
+    info->show();
+}
+
+void MainWindow::openPropertiesForSelection() {
+    const QStringList ids = selectedTaskIds();
+    if (ids.isEmpty()) {
+        return;
+    }
+    // One Progress dialog per selected task, same as double-clicking each row.
+    for (const QString &id : ids) {
+        auto *dlg = new ProgressDialog(client_, id, this);
+        dlg->show();
+    }
+}
+
+// docs/03-gui-spec.md §1 lists a fuller row menu (Open · Open With · Open Folder ·
+// Move/Rename · Redownload · Refresh Download Address · Add to Queue ▸ · ...). Those all
+// need dialogs or state this build order hasn't reached yet (Options for file-type
+// associations, Batch for Add to Queue) — offering them now would be a fake affordance,
+// same reasoning as the disabled Scheduler/Speed Limiter menu entries above.
+void MainWindow::showTableContextMenu(const QPoint &pos) {
+    const QModelIndex idx = view_->indexAt(pos);
+    if (idx.isValid() && view_->selectionModel() && !view_->selectionModel()->isSelected(idx)) {
+        view_->selectionModel()->setCurrentIndex(
+            idx, QItemSelectionModel::ClearAndSelect | QItemSelectionModel::Rows);
+    }
+    if (selectedTaskIds().isEmpty()) {
+        return;
+    }
+
+    QMenu menu(this);
+    menu.addAction(actResume_);
+    menu.addAction(actPause_);
+    menu.addAction(actStop_);
+    menu.addSeparator();
+    menu.addAction(actRemove_);
+    menu.addSeparator();
+    menu.addAction(actProperties_);
+    menu.exec(view_->viewport()->mapToGlobal(pos));
+}
+
 void MainWindow::onFilterChanged(const TaskSelection &selection) {
     proxy_->setSelection(selection);
     // TODO(gui): also push proxy_->asTaskFilter() to a fresh download.list once the daemon
@@ -315,7 +376,7 @@ void MainWindow::refreshCounts() {
                               .arg(shown)
                               .arg(total)
                               .arg(active)
-                              .arg(humanRate(globalDownBps_)));
+                              .arg(fmt::rate(globalDownBps_)));
 }
 
 QStringList MainWindow::selectedTaskIds() const {
diff --git a/gui/src/mainwindow/MainWindow.hpp b/gui/src/mainwindow/MainWindow.hpp
index edaf3b3..d175ad6 100644
--- a/gui/src/mainwindow/MainWindow.hpp
+++ b/gui/src/mainwindow/MainWindow.hpp
@@ -1,13 +1,16 @@
 // The main window. Lane GUI.
 //
-// M1 slice: dialogs and the tray still come later. This is the menus + toolbar + splitter
-// (category tree | table), the table driven by mockd, a status-bar connection dot, an
-// offline banner instead of a modal, and the actions that need no dialog.
+// M1 slice: the tray and the Options/Scheduler/Speed-Limiter/Batch/Grabber dialogs still
+// come later. This is the menus + toolbar + splitter (category tree | table), the table
+// driven by mockd, a status-bar connection dot, an offline banner instead of a modal, the
+// Add URL -> File Info flow, and a per-task progress dialog.
 
 #pragma once
 
 #include <QHash>
+#include <QJsonArray>
 #include <QMainWindow>
+#include <QPoint>
 
 #include "models/DownloadFilterProxy.hpp"
 #include "rpc/Protocol.hpp"
@@ -49,6 +52,10 @@ class MainWindow : public QMainWindow {
     void resumeAll();
     void pauseAll();
 
+    void openAddUrlDialog();
+    void openPropertiesForSelection();
+    void showTableContextMenu(const QPoint &pos);
+
   private:
     void buildActions();
     void buildMenus();
@@ -73,6 +80,10 @@ class MainWindow : public QMainWindow {
     QAction *actRemove_ = nullptr;
     QAction *actResumeAll_ = nullptr;
     QAction *actPauseAll_ = nullptr;
+    QAction *actProperties_ = nullptr;
+
+    QJsonArray categoriesCache_;
+    QJsonArray queuesCache_;
 
     QLabel *connDot_;
     QLabel *connText_;
diff --git a/gui/src/models/DownloadTableModel.cpp b/gui/src/models/DownloadTableModel.cpp
index 34ad12d..3fd14dc 100644
--- a/gui/src/models/DownloadTableModel.cpp
+++ b/gui/src/models/DownloadTableModel.cpp
@@ -4,16 +4,13 @@
 
 #include <QLocale>
 
+#include "util/Format.hpp"
+
 namespace velox::gui {
 namespace {
 
-QString humanBytes(qint64 n) {
-    if (n < 0) {
-        return QStringLiteral("—");
-    }
-    return QLocale().formattedDataSize(n, 2, QLocale::DataSizeIecFormat);
-}
-
+// The table wants a blank Speed cell when idle, not "0 B/s" — fmt::rate is for the status
+// bar, which does want the zero. Kept local for that one difference.
 QString humanRate(qint64 bps) {
     if (bps <= 0) {
         return QString();
@@ -22,19 +19,6 @@ QString humanRate(qint64 bps) {
         QLocale().formattedDataSize(bps, 1, QLocale::DataSizeIecFormat));
 }
 
-QString humanEta(qint64 secs) {
-    if (secs < 0) {
-        return QString();
-    }
-    const qint64 h = secs / 3600;
-    const qint64 m = (secs % 3600) / 60;
-    const qint64 s = secs % 60;
-    return QStringLiteral("%1:%2:%3")
-        .arg(h, 2, 10, QLatin1Char('0'))
-        .arg(m, 2, 10, QLatin1Char('0'))
-        .arg(s, 2, 10, QLatin1Char('0'));
-}
-
 QString stateLabel(const QString &state) {
     static const QHash<QString, QString> kLabels = {
         {QStringLiteral("new"), DownloadTableModel::tr("New")},
@@ -119,7 +103,7 @@ QVariant DownloadTableModel::data(const QModelIndex &index, int role) const {
         case ColQueue:
             return r.queuePosition >= 0 ? QString::number(r.queuePosition) : QString();
         case ColSize:
-            return humanBytes(r.sizeBytes);
+            return fmt::bytes(r.sizeBytes);
         case ColStatus:
             if (r.state == QLatin1String("downloading")) {
                 const double p = progressOf(r);
@@ -128,7 +112,7 @@ QVariant DownloadTableModel::data(const QModelIndex &index, int role) const {
             }
             return stateLabel(r.state);
         case ColTimeLeft:
-            return r.state == QLatin1String("downloading") ? humanEta(r.etaSeconds) : QString();
+            return r.state == QLatin1String("downloading") ? fmt::eta(r.etaSeconds) : QString();
         case ColSpeed:
             return r.state == QLatin1String("downloading") ? humanRate(r.speedBps) : QString();
         case ColLastTry:
diff --git a/gui/src/util/Format.hpp b/gui/src/util/Format.hpp
new file mode 100644
index 0000000..999d694
--- /dev/null
+++ b/gui/src/util/Format.hpp
@@ -0,0 +1,43 @@
+// Shared human-readable formatting. Lane GUI.
+//
+// Pulled out once three places (the table model, the main window status bar, the
+// progress dialog) all wanted the same "bytes / rate / eta" strings.
+
+#pragma once
+
+#include <QCoreApplication>
+#include <QLocale>
+#include <QString>
+
+namespace velox::gui::fmt {
+
+inline QString bytes(qint64 n) {
+    if (n < 0) {
+        return QStringLiteral("—");
+    }
+    return QLocale().formattedDataSize(n, 2, QLocale::DataSizeIecFormat);
+}
+
+inline QString rate(qint64 bytesPerSec) {
+    if (bytesPerSec <= 0) {
+        return QCoreApplication::translate("velox::gui::fmt", "0 B/s");
+    }
+    return QCoreApplication::translate("velox::gui::fmt", "%1/s")
+        .arg(QLocale().formattedDataSize(bytesPerSec, 1, QLocale::DataSizeIecFormat));
+}
+
+/// HH:MM:SS, or empty for a negative (unknown) eta.
+inline QString eta(qint64 secs) {
+    if (secs < 0) {
+        return QString();
+    }
+    const qint64 h = secs / 3600;
+    const qint64 m = (secs % 3600) / 60;
+    const qint64 s = secs % 60;
+    return QStringLiteral("%1:%2:%3")
+        .arg(h, 2, 10, QLatin1Char('0'))
+        .arg(m, 2, 10, QLatin1Char('0'))
+        .arg(s, 2, 10, QLatin1Char('0'));
+}
+
+}  // namespace velox::gui::fmt
diff --git a/gui/src/widgets/SegmentBarsWidget.cpp b/gui/src/widgets/SegmentBarsWidget.cpp
new file mode 100644
index 0000000..6865c83
--- /dev/null
+++ b/gui/src/widgets/SegmentBarsWidget.cpp
@@ -0,0 +1,79 @@
+#include "widgets/SegmentBarsWidget.hpp"
+
+#include <algorithm>
+
+#include <QGridLayout>
+#include <QHBoxLayout>
+#include <QLabel>
+#include <QLocale>
+#include <QProgressBar>
+
+namespace velox::gui {
+namespace {
+constexpr int kColumns = 2;  // pairs of (index, bar, speed) per docs/03-gui-spec.md §3
+}  // namespace
+
+SegmentBarsWidget::SegmentBarsWidget(QWidget *parent)
+    : QWidget(parent), grid_(new QGridLayout(this)) {
+    grid_->setContentsMargins(4, 4, 4, 4);
+    grid_->setHorizontalSpacing(12);
+}
+
+SegmentBarsWidget::Row &SegmentBarsWidget::rowFor(int i) {
+    while (static_cast<int>(rows_.size()) <= i) {
+        const int idx = static_cast<int>(rows_.size());
+        Row row;
+        row.container = new QWidget(this);
+        auto *layout = new QHBoxLayout(row.container);
+        layout->setContentsMargins(0, 0, 0, 0);
+        row.indexLabel = new QLabel(row.container);
+        row.indexLabel->setMinimumWidth(18);
+        row.bar = new QProgressBar(row.container);
+        row.bar->setRange(0, 10000);
+        row.bar->setTextVisible(true);
+        row.speedLabel = new QLabel(row.container);
+        row.speedLabel->setMinimumWidth(90);
+        layout->addWidget(row.indexLabel);
+        layout->addWidget(row.bar, 1);
+        layout->addWidget(row.speedLabel);
+
+        grid_->addWidget(row.container, idx / kColumns, idx % kColumns);
+        rows_.push_back(row);
+    }
+    return rows_[static_cast<std::size_t>(i)];
+}
+
+void SegmentBarsWidget::setSegments(const std::vector<SegmentInfo> &segments) {
+    for (std::size_t i = 0; i < segments.size(); ++i) {
+        Row &row = rowFor(static_cast<int>(i));
+        const SegmentInfo &seg = segments[i];
+        row.container->setVisible(true);
+        row.indexLabel->setText(QString::number(seg.index + 1));
+
+        if (seg.totalBytes > 0) {
+            const double pct = std::clamp(
+                static_cast<double>(seg.downloadedBytes) / static_cast<double>(seg.totalBytes), 0.0,
+                1.0);
+            row.bar->setRange(0, 10000);
+            row.bar->setValue(static_cast<int>(pct * 10000.0));
+            row.bar->setFormat(QStringLiteral("%p%"));
+        } else {
+            row.bar->setRange(0, 0);  // indeterminate: range not known yet
+            row.bar->setFormat(QString());
+        }
+
+        row.speedLabel->setText(seg.state == QLatin1String("downloading")
+                                    ? tr("%1/s").arg(QLocale().formattedDataSize(
+                                          seg.speedBps, 1, QLocale::DataSizeIecFormat))
+                                    : seg.state);
+    }
+    for (std::size_t i = segments.size(); i < rows_.size(); ++i) {
+        rows_[i].container->setVisible(false);
+    }
+}
+
+void SegmentBarsWidget::clear() {
+    setSegments({});
+}
+
+}  // namespace velox::gui
diff --git a/gui/src/widgets/SegmentBarsWidget.hpp b/gui/src/widgets/SegmentBarsWidget.hpp
new file mode 100644
index 0000000..2dc3dfa
--- /dev/null
+++ b/gui/src/widgets/SegmentBarsWidget.hpp
@@ -0,0 +1,52 @@
+// The per-segment progress grid in the download progress dialog. Lane GUI.
+//
+// docs/03-gui-spec.md §3: one bar per connection, two columns, "N ████░░░ Receiving
+// X MB/s". Row widgets are created once per segment index and reused across ticks —
+// never rebuilt on a progress event, same discipline as the table model.
+
+#pragma once
+
+#include <QWidget>
+#include <vector>
+
+class QGridLayout;
+class QLabel;
+class QProgressBar;
+
+namespace velox::gui {
+
+struct SegmentInfo {
+    qint64 index = 0;
+    qint64 downloadedBytes = 0;
+    qint64 totalBytes = -1;  // -1 == unknown (segment range not yet known)
+    qint64 speedBps = 0;
+    QString state;  // "downloading", "pending", "done", ... — see contract's SegmentState
+};
+
+class SegmentBarsWidget : public QWidget {
+    Q_OBJECT
+
+  public:
+    explicit SegmentBarsWidget(QWidget *parent = nullptr);
+
+  public slots:
+    /// Full replace of the segment set. Rows for indices no longer present are hidden,
+    /// not destroyed, so re-showing them later (a re-segmented retry) is cheap.
+    void setSegments(const std::vector<SegmentInfo> &segments);
+    void clear();
+
+  private:
+    struct Row {
+        QWidget *container = nullptr;
+        QLabel *indexLabel = nullptr;
+        QProgressBar *bar = nullptr;
+        QLabel *speedLabel = nullptr;
+    };
+
+    Row &rowFor(int i);
+
+    QGridLayout *grid_;
+    std::vector<Row> rows_;
+};
+
+}  // namespace velox::gui
diff --git a/gui/src/widgets/SpeedGraphWidget.cpp b/gui/src/widgets/SpeedGraphWidget.cpp
new file mode 100644
index 0000000..555d36c
--- /dev/null
+++ b/gui/src/widgets/SpeedGraphWidget.cpp
@@ -0,0 +1,96 @@
+#include "widgets/SpeedGraphWidget.hpp"
+
+#include <algorithm>
+
+#include <QLocale>
+#include <QPainter>
+
+namespace velox::gui {
+
+SpeedGraphWidget::SpeedGraphWidget(QWidget *parent) : QWidget(parent) {
+    setAttribute(Qt::WA_OpaquePaintEvent);
+    // Left invalid on purpose: addSample()'s `!isValid()` branch is what makes the very
+    // first sample record immediately instead of waiting up to 1 s after construction.
+}
+
+void SpeedGraphWidget::addSample(qint64 bytesPerSec) {
+    pending_ = bytesPerSec;
+    if (!sinceLastBucket_.isValid() || sinceLastBucket_.elapsed() >= 1000) {
+        samples_[static_cast<std::size_t>(head_)] = pending_;
+        head_ = (head_ + 1) % kWindowSeconds;
+        count_ = std::min(count_ + 1, kWindowSeconds);
+        sinceLastBucket_.restart();
+        update();
+    }
+}
+
+void SpeedGraphWidget::clear() {
+    samples_.fill(0);
+    count_ = 0;
+    head_ = 0;
+    pending_ = 0;
+    sinceLastBucket_.restart();
+    update();
+}
+
+void SpeedGraphWidget::paintEvent(QPaintEvent * /*event*/) {
+    QPainter p(this);
+    p.setRenderHint(QPainter::Antialiasing);
+    p.fillRect(rect(), palette().base());
+
+    if (count_ < 2) {
+        p.setPen(palette().mid().color());
+        p.drawText(rect(), Qt::AlignCenter, tr("collecting speed samples…"));
+        return;
+    }
+
+    qint64 maxVal = 1;
+    for (int i = 0; i < count_; ++i) {
+        maxVal = std::max(maxVal, samples_[static_cast<std::size_t>(i)]);
+    }
+
+    const double w = width();
+    const double h = height();
+    const double stepX = w / static_cast<double>(kWindowSeconds - 1);
+    // Oldest sample is at `head_` once the buffer has wrapped; before that, index 0.
+    const int oldest = (count_ == kWindowSeconds) ? head_ : 0;
+
+    const auto yOf = [&](qint64 v) {
+        return h - (static_cast<double>(v) / static_cast<double>(maxVal)) * (h - 4.0) - 2.0;
+    };
+
+    path_.clear();
+    path_.moveTo(0.0, h);
+    for (int i = 0; i < count_; ++i) {
+        const qint64 v = samples_[static_cast<std::size_t>((oldest + i) % kWindowSeconds)];
+        // Right-align: the newest sample sits at the right edge.
+        const double x = w - static_cast<double>(count_ - 1 - i) * stepX;
+        path_.lineTo(x, yOf(v));
+    }
+    path_.lineTo(w, h);  // the last sample's x is always the right edge
+    path_.closeSubpath();
+
+    QColor fill = palette().highlight().color();
+    fill.setAlpha(60);
+    p.fillPath(path_, fill);
+
+    // Redraw just the top edge as a stroked line (reuses the same path_ object).
+    path_.clear();
+    for (int i = 0; i < count_; ++i) {
+        const qint64 v = samples_[static_cast<std::size_t>((oldest + i) % kWindowSeconds)];
+        const double x = w - static_cast<double>(count_ - 1 - i) * stepX;
+        if (i == 0) {
+            path_.moveTo(x, yOf(v));
+        } else {
+            path_.lineTo(x, yOf(v));
+        }
+    }
+    p.strokePath(path_, QPen(palette().highlight().color(), 1.5));
+
+    p.setPen(palette().text().color());
+    p.drawText(
+        rect().adjusted(4, 2, -4, 0), Qt::AlignLeft | Qt::AlignTop,
+        tr("%1/s").arg(QLocale().formattedDataSize(pending_, 1, QLocale::DataSizeIecFormat)));
+}
+
+}  // namespace velox::gui
diff --git a/gui/src/widgets/SpeedGraphWidget.hpp b/gui/src/widgets/SpeedGraphWidget.hpp
new file mode 100644
index 0000000..468ce69
--- /dev/null
+++ b/gui/src/widgets/SpeedGraphWidget.hpp
@@ -0,0 +1,51 @@
+// 60-second rolling speed graph. Lane GUI.
+//
+// docs/03-gui-spec.md §3: "speed graph, 60 s rolling window, filled area, 1 Hz". A fixed
+// ring buffer and one reused QPainterPath — no allocation per sample or per repaint.
+
+#pragma once
+
+#include <array>
+
+#include <QElapsedTimer>
+#include <QPainterPath>
+#include <QWidget>
+
+namespace velox::gui {
+
+class SpeedGraphWidget : public QWidget {
+    Q_OBJECT
+
+  public:
+    explicit SpeedGraphWidget(QWidget *parent = nullptr);
+
+    QSize minimumSizeHint() const override { return {220, 60}; }
+    QSize sizeHint() const override { return {320, 90}; }
+
+  public slots:
+    /// Safe to call more often than 1 Hz (e.g. once per progress tick); a new bucket is
+    /// only recorded once a second has elapsed since the last one; the value the second
+    /// closes on is whatever the most recent call passed.
+    void addSample(qint64 bytesPerSec);
+    void clear();
+
+    /// Test-only: number of recorded buckets (saturates at kWindowSeconds). Not used by
+    /// production code — exists so the 1 Hz throttling and ring-buffer wrap can be
+    /// asserted on without repainting.
+    int debugSampleCount() const noexcept { return count_; }
+
+  protected:
+    void paintEvent(QPaintEvent *event) override;
+
+  private:
+    static constexpr int kWindowSeconds = 60;
+
+    std::array<qint64, kWindowSeconds> samples_{};
+    int count_ = 0;  // valid samples, saturates at kWindowSeconds
+    int head_ = 0;   // ring index the NEXT sample will occupy
+    qint64 pending_ = 0;
+    QElapsedTimer sinceLastBucket_;
+    QPainterPath path_;  // scratch, reused every paint — never reallocated per frame
+};
+
+}  // namespace velox::gui
diff --git a/gui/tests/CMakeLists.txt b/gui/tests/CMakeLists.txt
index 3428ead..ce8f654 100644
--- a/gui/tests/CMakeLists.txt
+++ b/gui/tests/CMakeLists.txt
@@ -44,6 +44,44 @@ set_tests_properties(gui_rtl PROPERTIES
     LABELS "gui"
     ENVIRONMENT "QT_QPA_PLATFORM=offscreen")
 
+# tst_segmentbarswidget — the per-connection bar grid.
+#   Red when: a determinate segment stops rendering its percentage, an unknown-length
+#   segment stops falling back to the indeterminate range, a shrinking segment set
+#   destroys rows instead of hiding them, or rows start getting rebuilt per tick.
+add_executable(tst_segmentbarswidget tst_segmentbarswidget.cpp)
+target_compile_features(tst_segmentbarswidget PRIVATE cxx_std_23)
+target_compile_options(tst_segmentbarswidget PRIVATE -Wall -Wextra -Wpedantic -Werror)
+target_link_libraries(tst_segmentbarswidget PRIVATE velox-gui-lib Qt6::Widgets Qt6::Test)
+add_test(NAME gui_segmentbarswidget COMMAND tst_segmentbarswidget)
+set_tests_properties(gui_segmentbarswidget PROPERTIES
+    LABELS "gui"
+    ENVIRONMENT "QT_QPA_PLATFORM=offscreen")
+
+# tst_speedgraphwidget — the 60 s rolling speed graph.
+#   Red when: addSample stops throttling bursts to 1 Hz, the bucket count stops
+#   incrementing on genuinely separated samples, clear() leaves stale state, or painting
+#   crashes before two samples exist.
+add_executable(tst_speedgraphwidget tst_speedgraphwidget.cpp)
+target_compile_features(tst_speedgraphwidget PRIVATE cxx_std_23)
+target_compile_options(tst_speedgraphwidget PRIVATE -Wall -Wextra -Wpedantic -Werror)
+target_link_libraries(tst_speedgraphwidget PRIVATE velox-gui-lib Qt6::Widgets Qt6::Test)
+add_test(NAME gui_speedgraphwidget COMMAND tst_speedgraphwidget)
+set_tests_properties(gui_speedgraphwidget PROPERTIES
+    LABELS "gui"
+    ENVIRONMENT "QT_QPA_PLATFORM=offscreen")
+
+# tst_fileinfodialog — FileInfoDialog::buildSpec, the pure DownloadSpec builder.
+#   Red when: an empty optional field starts getting sent instead of omitted, or the
+#   queueId stops being dropped for a startMode other than "queue".
+add_executable(tst_fileinfodialog tst_fileinfodialog.cpp)
+target_compile_features(tst_fileinfodialog PRIVATE cxx_std_23)
+target_compile_options(tst_fileinfodialog PRIVATE -Wall -Wextra -Wpedantic -Werror)
+target_link_libraries(tst_fileinfodialog PRIVATE velox-gui-lib Qt6::Widgets Qt6::Test)
+add_test(NAME gui_fileinfodialog COMMAND tst_fileinfodialog)
+set_tests_properties(gui_fileinfodialog PROPERTIES
+    LABELS "gui"
+    ENVIRONMENT "QT_QPA_PLATFORM=offscreen")
+
 # gui_no_download_logic — CLAUDE.md §3 as an executable check, not a hope.
 #   Red when: a download-logic token (curl, raw pwrite, sqlite, QSqlDatabase) appears
 #   under gui/src. grep exits 0 only when it finds a match, so a hit fails the test.
diff --git a/gui/tests/tst_fileinfodialog.cpp b/gui/tests/tst_fileinfodialog.cpp
new file mode 100644
index 0000000..3e2e27d
--- /dev/null
+++ b/gui/tests/tst_fileinfodialog.cpp
@@ -0,0 +1,66 @@
+// FileInfoDialog::buildSpec unit tests. Lane GUI.
+//
+// Pure function, no widgets involved — see the comment on the declaration. Red when an
+// optional field starts being sent empty instead of omitted, or queueId leaks into a spec
+// whose startMode isn't "queue".
+
+#include <QJsonObject>
+#include <QtTest>
+
+#include "dialogs/FileInfoDialog.hpp"
+
+using velox::gui::FileInfoDialog;
+
+class TstFileInfoDialog : public QObject {
+    Q_OBJECT
+
+  private slots:
+    void requiredFieldsAlwaysPresent();
+    void emptyOptionalFieldsAreOmitted();
+    void fullSpecIncludesEveryField();
+    void queueIdOnlySentForQueueStartMode();
+};
+
+void TstFileInfoDialog::requiredFieldsAlwaysPresent() {
+    const QJsonObject spec =
+        FileInfoDialog::buildSpec("https://example.test/file.bin", "", "", "", "", 0, 0, "now", "");
+    QCOMPARE(spec.value("url").toString(), QStringLiteral("https://example.test/file.bin"));
+    QCOMPARE(spec.value("startMode").toString(), QStringLiteral("now"));
+}
+
+void TstFileInfoDialog::emptyOptionalFieldsAreOmitted() {
+    const QJsonObject spec =
+        FileInfoDialog::buildSpec("https://example.test/file.bin", "", "", "", "", 0, 0, "now", "");
+    QVERIFY(!spec.contains("filename"));
+    QVERIFY(!spec.contains("saveDir"));
+    QVERIFY(!spec.contains("categoryId"));
+    QVERIFY(!spec.contains("description"));
+    QVERIFY(!spec.contains("segments"));
+    QVERIFY(!spec.contains("bufferBytes"));
+    QVERIFY(!spec.contains("queueId"));
+}
+
+void TstFileInfoDialog::fullSpecIncludesEveryField() {
+    const QJsonObject spec =
+        FileInfoDialog::buildSpec("https://example.test/file.bin", "file.bin", "/home/x/Downloads",
+                                  "cat1", "a note", 8, 4 * 1024 * 1024, "later", "");
+    QCOMPARE(spec.value("filename").toString(), QStringLiteral("file.bin"));
+    QCOMPARE(spec.value("saveDir").toString(), QStringLiteral("/home/x/Downloads"));
+    QCOMPARE(spec.value("categoryId").toString(), QStringLiteral("cat1"));
+    QCOMPARE(spec.value("description").toString(), QStringLiteral("a note"));
+    QCOMPARE(spec.value("segments").toInt(), 8);
+    QCOMPARE(spec.value("bufferBytes").toDouble(), static_cast<double>(4 * 1024 * 1024));
+}
+
+void TstFileInfoDialog::queueIdOnlySentForQueueStartMode() {
+    const QJsonObject queued = FileInfoDialog::buildSpec("https://example.test/file.bin", "", "",
+                                                         "", "", 0, 0, "queue", "q1");
+    QCOMPARE(queued.value("queueId").toString(), QStringLiteral("q1"));
+
+    const QJsonObject notQueued = FileInfoDialog::buildSpec("https://example.test/file.bin", "", "",
+                                                            "", "", 0, 0, "now", "q1");
+    QVERIFY(!notQueued.contains("queueId"));
+}
+
+QTEST_MAIN(TstFileInfoDialog)
+#include "tst_fileinfodialog.moc"
diff --git a/gui/tests/tst_segmentbarswidget.cpp b/gui/tests/tst_segmentbarswidget.cpp
new file mode 100644
index 0000000..c4c66d6
--- /dev/null
+++ b/gui/tests/tst_segmentbarswidget.cpp
@@ -0,0 +1,94 @@
+// SegmentBarsWidget unit tests. Lane GUI.
+//
+// Red when: a row stops being reused across ticks (rebuilt instead of patched), a
+// zero/unknown-length segment stops rendering as indeterminate, or a shrinking segment
+// set leaves stale rows visible instead of hiding them.
+
+#include <QProgressBar>
+#include <QtTest>
+
+#include "widgets/SegmentBarsWidget.hpp"
+
+using velox::gui::SegmentBarsWidget;
+using velox::gui::SegmentInfo;
+
+class TstSegmentBarsWidget : public QObject {
+    Q_OBJECT
+
+  private slots:
+    void determinateShowsPercent();
+    void unknownLengthIsIndeterminate();
+    void shrinkingSetHidesStaleRows();
+    void rowsAreReusedNotRebuilt();
+};
+
+void TstSegmentBarsWidget::determinateShowsPercent() {
+    SegmentBarsWidget w;
+    SegmentInfo s;
+    s.index = 0;
+    s.downloadedBytes = 50;
+    s.totalBytes = 200;
+    s.state = QStringLiteral("downloading");
+    w.setSegments({s});
+
+    auto *bar = w.findChild<QProgressBar *>();
+    QVERIFY(bar != nullptr);
+    QCOMPARE(bar->minimum(), 0);
+    QCOMPARE(bar->maximum(), 10000);
+    QCOMPARE(bar->value(), 2500);  // 50/200 == 25%
+}
+
+void TstSegmentBarsWidget::unknownLengthIsIndeterminate() {
+    SegmentBarsWidget w;
+    SegmentInfo s;
+    s.index = 0;
+    s.totalBytes = -1;  // range not known yet
+    w.setSegments({s});
+
+    auto *bar = w.findChild<QProgressBar *>();
+    QVERIFY(bar != nullptr);
+    QCOMPARE(bar->minimum(), 0);
+    QCOMPARE(bar->maximum(), 0);  // Qt's indeterminate-range convention
+}
+
+void TstSegmentBarsWidget::shrinkingSetHidesStaleRows() {
+    SegmentBarsWidget w;
+    SegmentInfo a;
+    a.index = 0;
+    a.totalBytes = 100;
+    SegmentInfo b;
+    b.index = 1;
+    b.totalBytes = 100;
+    w.setSegments({a, b});
+
+    const auto barsBefore = w.findChildren<QProgressBar *>();
+    QCOMPARE(barsBefore.size(), 2);
+    for (auto *bar : barsBefore) {
+        QVERIFY(!bar->parentWidget()->isHidden());
+    }
+
+    w.setSegments({a});  // segment 1 dropped (re-segmented retry with fewer connections)
+
+    const auto barsAfter = w.findChildren<QProgressBar *>();
+    QCOMPARE(barsAfter.size(), 2);  // row not destroyed...
+    QVERIFY(!barsAfter[0]->parentWidget()->isHidden());
+    QVERIFY(barsAfter[1]->parentWidget()->isHidden());  // ...just hidden
+}
+
+void TstSegmentBarsWidget::rowsAreReusedNotRebuilt() {
+    SegmentBarsWidget w;
+    SegmentInfo s;
+    s.index = 0;
+    s.totalBytes = 100;
+    w.setSegments({s});
+    auto *barFirst = w.findChild<QProgressBar *>();
+    QVERIFY(barFirst != nullptr);
+
+    s.downloadedBytes = 40;
+    w.setSegments({s});
+    auto *barSecond = w.findChild<QProgressBar *>();
+    QCOMPARE(barFirst, barSecond);  // same widget instance, just repainted
+}
+
+QTEST_MAIN(TstSegmentBarsWidget)
+#include "tst_segmentbarswidget.moc"
diff --git a/gui/tests/tst_speedgraphwidget.cpp b/gui/tests/tst_speedgraphwidget.cpp
new file mode 100644
index 0000000..1042f5c
--- /dev/null
+++ b/gui/tests/tst_speedgraphwidget.cpp
@@ -0,0 +1,73 @@
+// SpeedGraphWidget unit tests. Lane GUI.
+//
+// Red when: addSample stops throttling to 1 Hz (a burst of ticks would flood the ring
+// buffer and skew the 60 s window), the sample count stops saturating at the window size,
+// or painting crashes before two samples have been recorded (the "collecting…" branch).
+
+#include <QtTest>
+
+#include "widgets/SpeedGraphWidget.hpp"
+
+using velox::gui::SpeedGraphWidget;
+
+class TstSpeedGraphWidget : public QObject {
+    Q_OBJECT
+
+  private slots:
+    void burstsWithinASecondCountOnce();
+    void separatedSamplesEachCount();
+    void clearResetsCount();
+    void paintDoesNotCrashBeforeTwoSamples();
+};
+
+void TstSpeedGraphWidget::burstsWithinASecondCountOnce() {
+    SpeedGraphWidget w;
+    QCOMPARE(w.debugSampleCount(), 0);
+    // The first call always records (no prior bucket); the rest land inside the same
+    // second and must be coalesced into that one bucket.
+    for (int i = 0; i < 20; ++i) {
+        w.addSample(1000 + i);
+    }
+    QCOMPARE(w.debugSampleCount(), 1);
+}
+
+void TstSpeedGraphWidget::separatedSamplesEachCount() {
+    SpeedGraphWidget w;
+    w.addSample(100);
+    QCOMPARE(w.debugSampleCount(), 1);
+    QTest::qWait(1100);
+    w.addSample(200);
+    QCOMPARE(w.debugSampleCount(), 2);
+    QTest::qWait(1100);
+    w.addSample(300);
+    QCOMPARE(w.debugSampleCount(), 3);
+}
+
+void TstSpeedGraphWidget::clearResetsCount() {
+    SpeedGraphWidget w;
+    w.addSample(100);
+    QTest::qWait(1100);
+    w.addSample(200);
+    QVERIFY(w.debugSampleCount() > 0);
+    w.clear();
+    QCOMPARE(w.debugSampleCount(), 0);
+}
+
+void TstSpeedGraphWidget::paintDoesNotCrashBeforeTwoSamples() {
+    SpeedGraphWidget w;
+    w.resize(200, 60);
+    const QPixmap empty = w.grab();
+    QVERIFY(!empty.isNull());
+
+    w.addSample(500);
+    const QPixmap oneSample = w.grab();
+    QVERIFY(!oneSample.isNull());
+
+    QTest::qWait(1100);
+    w.addSample(700);
+    const QPixmap twoSamples = w.grab();
+    QVERIFY(!twoSamples.isNull());
+}
+
+QTEST_MAIN(TstSpeedGraphWidget)
+#include "tst_speedgraphwidget.moc"