diff --git a/CMakeLists.txt b/CMakeLists.txt
index b021283..36cb21e 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -38,6 +38,10 @@ qt_add_executable(llink
         src/particlelistmodel.cpp
         src/textinputdialog.h
         src/textinputdialog.cpp
+        src/createstreamdialog.h
+        src/createstreamdialog.cpp
+        src/memberpickerdialog.h
+        src/memberpickerdialog.cpp
 )
 
 qt_add_resources(llink
diff --git a/src/MainWindow.cpp b/src/MainWindow.cpp
index 3466d56..c38b24e 100644
--- a/src/MainWindow.cpp
+++ b/src/MainWindow.cpp
@@ -5,10 +5,13 @@
 #include "MainWindow.h"
 #include "authdialog.h"
 #include "authmanager.h"
+#include "createstreamdialog.h"
+#include "memberpickerdialog.h"
 #include "settingsdialog.h"
 #include "textinputdialog.h"
 #include "ui_mainwindow.h"
 #include <QApplication>
+#include <QJsonDocument>
 #include <QHeaderView>
 #include <QItemSelectionModel>
 #include <QLabel>
@@ -23,7 +26,7 @@
 MainWindow::MainWindow(QWidget *parent)
     : QMainWindow(parent), m_trayIcon(nullptr), m_authManager(new AuthManager(this)), m_settingsDialog(nullptr),
       m_authDialog(nullptr), m_store(nullptr), m_networkStreamModel(nullptr), m_particleListModel(nullptr),
-      m_selectedParticleRow(-1), m_isDragging(false), m_textInputDialog(nullptr)
+      m_selectedParticleRow(-1), m_isDragging(false), m_textInputDialog(nullptr), m_createStreamDialog(nullptr)
 {
   m_authDialog = new AuthDialog(this);
   m_textInputDialog = new TextInputDialog(this);
@@ -110,6 +113,57 @@ MainWindow::MainWindow(QWidget *parent)
   // DocumentSend toolbar button opens text input dialog
   connect(ui->toolButton_3, &QToolButton::clicked, this, &MainWindow::showTextInputDialog);
 
+  // "New stream" button
+  m_createStreamDialog = new CreateStreamDialog(this);
+  connect(ui->pushButton, &QPushButton::clicked, this, [this]() {
+    if (m_selectedNetworkName.isEmpty())
+      return;
+    const Network *network = m_store->networkById(m_selectedNetworkName);
+    if (network)
+      m_createStreamDialog->setNetworkMembers(network->members);
+    m_createStreamDialog->show();
+    m_createStreamDialog->raise();
+    m_createStreamDialog->activateWindow();
+  });
+  connect(m_createStreamDialog, &CreateStreamDialog::streamRequested, this,
+          [this](const QString &name, const QString &visibility, const QStringList &members) {
+            m_store->createStream(m_selectedNetworkName, name, "", visibility, members);
+          });
+
+  // "Add members" toolbar button (ListAdd icon in right sidebar)
+  connect(ui->toolButton_7, &QToolButton::clicked, this, [this]() {
+    if (m_selectedStreamId.isEmpty() || m_selectedNetworkName.isEmpty())
+      return;
+    const Network *network = m_store->networkById(m_selectedNetworkName);
+    const Stream *stream = m_store->streamById(m_selectedStreamId);
+    if (!network || !stream)
+      return;
+
+    MemberPickerDialog picker("Add Members", this);
+    picker.setMembers(network->members, stream->memberEmails);
+
+    if (picker.exec() == QDialog::Accepted)
+    {
+      QStringList emails = picker.selectedEmails();
+      if (!emails.isEmpty())
+      {
+        auto *op = m_store->addStreamMembers(m_selectedStreamId, emails);
+        connect(op, &Operation::success, this, [this](const QJsonDocument &) {
+          auto *fetchOp = m_store->fetchStream(m_selectedStreamId);
+          connect(fetchOp, &Operation::success, this, [this](const QJsonDocument &) {
+            ui->membersList->clear();
+            const Stream *s = m_store->streamById(m_selectedStreamId);
+            if (s)
+            {
+              for (const QString &email : s->memberEmails)
+                ui->membersList->addItem(email.split("@")[0]);
+            }
+          });
+        });
+      }
+    }
+  });
+
   m_authManager->tryRestoreSession();
 
   setupTrayIcon();
@@ -286,6 +340,12 @@ void MainWindow::onParticleSelectionChanged(const QItemSelection &selected, cons
     {
       ui->label->setText("");
     }
+
+    // Mark seen on selection
+    if (!particle->seen)
+    {
+      m_store->markParticleSeen(particle->id);
+    }
   }
 
   updateStatusBar();
@@ -407,6 +467,11 @@ bool MainWindow::eventFilter(QObject *obj, QEvent *event)
       showTextInputDialog();
       return true;
     }
+    if (keyEvent->key() == Qt::Key_A && keyEvent->modifiers() == Qt::NoModifier && !m_selectedParticleId.isEmpty())
+    {
+      m_store->ackParticle(m_selectedParticleId);
+      return true;
+    }
   }
   return QMainWindow::eventFilter(obj, event);
 }
diff --git a/src/MainWindow.h b/src/MainWindow.h
index 8385f46..4dff0d6 100644
--- a/src/MainWindow.h
+++ b/src/MainWindow.h
@@ -18,6 +18,8 @@ class QLabel;
 QT_END_NAMESPACE
 
 class AuthDialog;
+class CreateStreamDialog;
+class MemberPickerDialog;
 class SettingsDialog;
 class TextInputDialog;
 
@@ -62,6 +64,7 @@ private:
 
   SettingsDialog *m_settingsDialog;
   TextInputDialog *m_textInputDialog;
+  CreateStreamDialog *m_createStreamDialog;
 
   // Data and models
   Store *m_store;
diff --git a/src/createstreamdialog.cpp b/src/createstreamdialog.cpp
new file mode 100644
index 0000000..2abea8e
--- /dev/null
+++ b/src/createstreamdialog.cpp
@@ -0,0 +1,80 @@
+#include "createstreamdialog.h"
+#include <QComboBox>
+#include <QDialogButtonBox>
+#include <QLabel>
+#include <QLineEdit>
+#include <QListWidget>
+#include <QVBoxLayout>
+
+CreateStreamDialog::CreateStreamDialog(QWidget *parent)
+    : QDialog(parent)
+{
+  setWindowTitle("New Stream");
+  setMinimumWidth(320);
+
+  auto *layout = new QVBoxLayout(this);
+
+  layout->addWidget(new QLabel("Stream name:"));
+  m_nameEdit = new QLineEdit(this);
+  m_nameEdit->setPlaceholderText("e.g. design-review");
+  layout->addWidget(m_nameEdit);
+
+  layout->addWidget(new QLabel("Visibility:"));
+  m_visibilityCombo = new QComboBox(this);
+  m_visibilityCombo->addItem("Everyone in network", "network_all");
+  m_visibilityCombo->addItem("Specific members", "custom");
+  layout->addWidget(m_visibilityCombo);
+
+  m_membersLabel = new QLabel("Select members:");
+  m_membersList = new QListWidget(this);
+  m_membersLabel->setVisible(false);
+  m_membersList->setVisible(false);
+  layout->addWidget(m_membersLabel);
+  layout->addWidget(m_membersList);
+
+  connect(m_visibilityCombo, &QComboBox::currentIndexChanged, this, [this](int) {
+    bool specific = (m_visibilityCombo->currentData().toString() == "custom");
+    m_membersLabel->setVisible(specific);
+    m_membersList->setVisible(specific);
+  });
+
+  auto *buttons = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel, this);
+  layout->addWidget(buttons);
+
+  connect(buttons, &QDialogButtonBox::accepted, this, [this]() {
+    QString name = m_nameEdit->text().trimmed();
+    if (name.isEmpty())
+      return;
+
+    QString visibility = m_visibilityCombo->currentData().toString();
+    QStringList members;
+    if (visibility == "custom")
+    {
+      for (int i = 0; i < m_membersList->count(); ++i)
+      {
+        auto *item = m_membersList->item(i);
+        if (item->checkState() == Qt::Checked)
+          members.append(item->data(Qt::UserRole).toString());
+      }
+    }
+
+    emit streamRequested(name, visibility, members);
+    m_nameEdit->clear();
+    m_visibilityCombo->setCurrentIndex(0);
+    accept();
+  });
+
+  connect(buttons, &QDialogButtonBox::rejected, this, &QDialog::reject);
+}
+
+void CreateStreamDialog::setNetworkMembers(const std::vector<Human> &members)
+{
+  m_membersList->clear();
+  for (const auto &human : members)
+  {
+    auto *item = new QListWidgetItem(human.email, m_membersList);
+    item->setFlags(item->flags() | Qt::ItemIsUserCheckable);
+    item->setCheckState(Qt::Unchecked);
+    item->setData(Qt::UserRole, human.email);
+  }
+}
diff --git a/src/createstreamdialog.h b/src/createstreamdialog.h
new file mode 100644
index 0000000..2dd34c5
--- /dev/null
+++ b/src/createstreamdialog.h
@@ -0,0 +1,34 @@
+#ifndef CREATESTREAMDIALOG_H
+#define CREATESTREAMDIALOG_H
+
+#include "models.h"
+#include <QDialog>
+
+QT_BEGIN_NAMESPACE
+class QLineEdit;
+class QComboBox;
+class QLabel;
+class QListWidget;
+QT_END_NAMESPACE
+
+class CreateStreamDialog : public QDialog
+{
+  Q_OBJECT
+
+public:
+  explicit CreateStreamDialog(QWidget *parent = nullptr);
+
+  /// Call before showing to populate the member checklist.
+  void setNetworkMembers(const std::vector<Human> &members);
+
+signals:
+  void streamRequested(const QString &name, const QString &visibility, const QStringList &memberEmails);
+
+private:
+  QLineEdit *m_nameEdit;
+  QComboBox *m_visibilityCombo;
+  QLabel *m_membersLabel;
+  QListWidget *m_membersList;
+};
+
+#endif // CREATESTREAMDIALOG_H
diff --git a/src/memberpickerdialog.cpp b/src/memberpickerdialog.cpp
new file mode 100644
index 0000000..6401098
--- /dev/null
+++ b/src/memberpickerdialog.cpp
@@ -0,0 +1,55 @@
+#include "memberpickerdialog.h"
+#include <QDialogButtonBox>
+#include <QLabel>
+#include <QListWidget>
+#include <QSet>
+#include <QVBoxLayout>
+
+MemberPickerDialog::MemberPickerDialog(const QString &title, QWidget *parent)
+    : QDialog(parent)
+{
+  setWindowTitle(title);
+  setMinimumWidth(300);
+
+  auto *layout = new QVBoxLayout(this);
+
+  m_list = new QListWidget(this);
+  layout->addWidget(m_list);
+
+  auto *buttons = new QDialogButtonBox(QDialogButtonBox::Ok | QDialogButtonBox::Cancel, this);
+  layout->addWidget(buttons);
+
+  connect(buttons, &QDialogButtonBox::accepted, this, &QDialog::accept);
+  connect(buttons, &QDialogButtonBox::rejected, this, &QDialog::reject);
+}
+
+void MemberPickerDialog::setMembers(const std::vector<Human> &members, const std::vector<QString> &exclude)
+{
+  m_list->clear();
+
+  QSet<QString> excludeSet;
+  for (const auto &e : exclude)
+    excludeSet.insert(e);
+
+  for (const auto &human : members)
+  {
+    if (excludeSet.contains(human.email))
+      continue;
+    auto *item = new QListWidgetItem(human.email, m_list);
+    item->setFlags(item->flags() | Qt::ItemIsUserCheckable);
+    item->setCheckState(Qt::Unchecked);
+    item->setData(Qt::UserRole, human.email);
+  }
+}
+
+QStringList MemberPickerDialog::selectedEmails() const
+{
+  QStringList result;
+  for (int i = 0; i < m_list->count(); ++i)
+  {
+    auto *item = m_list->item(i);
+    if (item->checkState() == Qt::Checked)
+      result.append(item->data(Qt::UserRole).toString());
+  }
+  return result;
+}
diff --git a/src/memberpickerdialog.h b/src/memberpickerdialog.h
new file mode 100644
index 0000000..ee06bcb
--- /dev/null
+++ b/src/memberpickerdialog.h
@@ -0,0 +1,29 @@
+#ifndef MEMBERPICKERDIALOG_H
+#define MEMBERPICKERDIALOG_H
+
+#include "models.h"
+#include <QDialog>
+
+QT_BEGIN_NAMESPACE
+class QListWidget;
+QT_END_NAMESPACE
+
+/// A simple dialog that shows a checklist of humans and returns the selected emails.
+class MemberPickerDialog : public QDialog
+{
+  Q_OBJECT
+
+public:
+  explicit MemberPickerDialog(const QString &title, QWidget *parent = nullptr);
+
+  /// Populate the checklist. Members whose emails appear in `exclude` are hidden.
+  void setMembers(const std::vector<Human> &members, const std::vector<QString> &exclude = {});
+
+  /// Returns the emails of all checked items.
+  QStringList selectedEmails() const;
+
+private:
+  QListWidget *m_list;
+};
+
+#endif // MEMBERPICKERDIALOG_H
diff --git a/src/networkstreammodel.cpp b/src/networkstreammodel.cpp
index 087744c..7a43291 100644
--- a/src/networkstreammodel.cpp
+++ b/src/networkstreammodel.cpp
@@ -12,6 +12,26 @@ NetworkStreamModel::NetworkStreamModel(Store *store, QObject *parent) : QAbstrac
     beginResetModel();
     endResetModel();
   });
+
+  // Granular update: repaint a single stream row when its properties change (e.g. unseen count)
+  connect(m_store, &Store::streamUpdated, this, [this](const QString &streamId) {
+    const auto &networks = m_store->networks();
+    for (int ni = 0; ni < networks.size(); ++ni)
+    {
+      const auto &streams = networks.at(ni).streams;
+      for (int si = 0; si < static_cast<int>(streams.size()); ++si)
+      {
+        if (streams[si].id == streamId)
+        {
+          // Build indices for both columns of this stream row
+          QModelIndex topLeft = index(si, 0, index(ni, 0));
+          QModelIndex bottomRight = index(si, 1, index(ni, 0));
+          emit dataChanged(topLeft, bottomRight, {Qt::DisplayRole, Qt::ForegroundRole});
+          return;
+        }
+      }
+    }
+  });
 }
 
 QModelIndex NetworkStreamModel::index(int row, int column, const QModelIndex &parent) const
diff --git a/src/particlelistmodel.cpp b/src/particlelistmodel.cpp
index 1aee198..b408d71 100644
--- a/src/particlelistmodel.cpp
+++ b/src/particlelistmodel.cpp
@@ -15,6 +15,22 @@ ParticleListModel::ParticleListModel(Store *store, QObject *parent)
       endResetModel();
     }
   });
+
+  // Granular update: repaint a single row when a particle property changes
+  connect(m_store, &Store::particleUpdated, this, [this](const QString &streamId, const QString &particleId) {
+    if (streamId != m_currentStreamId)
+      return;
+    const QList<Particle> &particles = m_store->particlesForStream(m_currentStreamId);
+    for (int i = 0; i < particles.size(); ++i)
+    {
+      if (particles.at(i).id == particleId)
+      {
+        QModelIndex idx = index(i, 0);
+        emit dataChanged(idx, idx, {Qt::DisplayRole, Qt::ForegroundRole});
+        return;
+      }
+    }
+  });
 }
 
 int ParticleListModel::rowCount(const QModelIndex &parent) const
diff --git a/src/store.cpp b/src/store.cpp
index 476a44a..1150597 100644
--- a/src/store.cpp
+++ b/src/store.cpp
@@ -10,35 +10,14 @@
 // Operation
 // ────────────────────────────────────────────────────────────────
 
-Operation::Operation(QObject *parent)
+Operation::Operation(QNetworkReply *reply, QObject *parent)
     : QObject(parent)
 {
-}
+  connect(this, &Operation::finished, this, &QObject::deleteLater);
 
-// ────────────────────────────────────────────────────────────────
-// Store — construction
-// ────────────────────────────────────────────────────────────────
+  connect(reply, &QNetworkReply::finished, this, [this, reply]() {
+    reply->deleteLater();
 
-Store::Store(QObject *parent)
-    : QObject(parent)
-{
-}
-
-// ────────────────────────────────────────────────────────────────
-// Operation helpers
-// ────────────────────────────────────────────────────────────────
-
-Operation *Store::makeOperation()
-{
-  auto *op = new Operation(this);
-  connect(op, &Operation::finished, op, &QObject::deleteLater);
-  return op;
-}
-
-void Store::wireReply(QNetworkReply *reply, Operation *op,
-                      std::function<void(const QJsonDocument &)> successHandler)
-{
-  connect(reply, &QNetworkReply::finished, this, [reply, op, successHandler = std::move(successHandler)]() {
     if (reply->error() != QNetworkReply::NoError)
     {
       QByteArray body = reply->readAll();
@@ -48,23 +27,26 @@ void Store::wireReply(QNetworkReply *reply, Operation *op,
       {
         message = reply->errorString();
       }
-      emit op->failed(message);
-      emit op->finished();
+      qWarning() << message;
+      emit failed(message);
+      emit finished();
       return;
     }
 
     QByteArray body = reply->readAll();
     QJsonDocument doc = body.isEmpty() ? QJsonDocument() : QJsonDocument::fromJson(body);
-    successHandler(doc);
+    emit success(doc);
+    emit finished();
   });
 }
 
-void Store::wireReply(QNetworkReply *reply, Operation *op)
+// ────────────────────────────────────────────────────────────────
+// Store — construction
+// ────────────────────────────────────────────────────────────────
+
+Store::Store(QObject *parent)
+    : QObject(parent)
 {
-  wireReply(reply, op, [op](const QJsonDocument &) {
-    emit op->success();
-    emit op->finished();
-  });
 }
 
 // ────────────────────────────────────────────────────────────────
@@ -381,23 +363,18 @@ const Particle *Store::particleById(const QString &id) const
 
 Operation *Store::loadStartupData()
 {
-  Operation *op = makeOperation();
   QNetworkReply *reply = NetworkManager::instance().get("/startup");
-
-  wireReply(reply, op, [this, op](const QJsonDocument &doc) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this](const QJsonDocument &doc) {
     if (!doc.isObject())
     {
-      emit op->failed("Invalid startup data");
-      emit op->finished();
+      qWarning() << "Invalid startup data";
       return;
     }
     populateFromStartupData(doc.object());
     emit startupDataLoaded();
     emit networksChanged();
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
@@ -407,51 +384,41 @@ Operation *Store::loadStartupData()
 
 Operation *Store::createNetwork(const QString &name)
 {
-  Operation *op = makeOperation();
-
   QJsonObject body;
   body["name"] = name;
 
   QNetworkReply *reply = NetworkManager::instance().post("/networks", QJsonDocument(body));
-
-  wireReply(reply, op, [this, op](const QJsonDocument &doc) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this](const QJsonDocument &doc) {
     if (doc.isObject())
     {
       upsertNetwork(parseNetwork(doc.object()));
       emit networksChanged();
     }
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
 Operation *Store::fetchNetworks()
 {
-  Operation *op = makeOperation();
   QNetworkReply *reply = NetworkManager::instance().get("/networks");
-
-  wireReply(reply, op, [this, op](const QJsonDocument &doc) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this](const QJsonDocument &doc) {
     const QJsonArray arr = doc.array();
     for (const QJsonValue &v : arr)
     {
       upsertNetwork(parseNetwork(v.toObject()));
     }
     emit networksChanged();
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
 Operation *Store::fetchNetwork(const QString &networkId)
 {
-  Operation *op = makeOperation();
   QNetworkReply *reply = NetworkManager::instance().get(QString("/networks/%1").arg(networkId));
-
-  wireReply(reply, op, [this, op, networkId](const QJsonDocument &doc) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this, networkId](const QJsonDocument &doc) {
     QJsonObject obj = doc.object();
     Network network = parseNetwork(obj);
 
@@ -464,17 +431,12 @@ Operation *Store::fetchNetwork(const QString &networkId)
     }
     upsertNetwork(network);
     emit networksChanged();
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
 Operation *Store::addNetworkMembers(const QString &networkId, const QStringList &emails)
 {
-  Operation *op = makeOperation();
-
   QJsonObject body;
   QJsonArray arr;
   for (const QString &e : emails)
@@ -485,30 +447,24 @@ Operation *Store::addNetworkMembers(const QString &networkId, const QStringList
 
   QNetworkReply *reply = NetworkManager::instance().post(
       QString("/networks/%1/members").arg(networkId), QJsonDocument(body));
-  wireReply(reply, op);
-  return op;
+  return new Operation(reply, this);
 }
 
 Operation *Store::removeNetworkMember(const QString &networkId, const QString &email)
 {
-  Operation *op = makeOperation();
   QNetworkReply *reply = NetworkManager::instance().del(
       QString("/networks/%1/members/%2").arg(networkId, email));
-  wireReply(reply, op);
-  return op;
+  return new Operation(reply, this);
 }
 
 Operation *Store::setStreamCapacity(const QString &networkId, int capacity)
 {
-  Operation *op = makeOperation();
-
   QJsonObject body;
   body["capacity"] = capacity;
 
   QNetworkReply *reply = NetworkManager::instance().put(
       QString("/networks/%1/capacity").arg(networkId), QJsonDocument(body));
-  wireReply(reply, op);
-  return op;
+  return new Operation(reply, this);
 }
 
 // ────────────────────────────────────────────────────────────────
@@ -519,8 +475,6 @@ Operation *Store::createStream(const QString &networkId, const QString &name,
                                const QString &description, const QString &visibility,
                                const QStringList &members)
 {
-  Operation *op = makeOperation();
-
   QJsonObject body;
   body["name"] = name;
   body["description"] = description;
@@ -534,27 +488,23 @@ Operation *Store::createStream(const QString &networkId, const QString &name,
 
   QNetworkReply *reply = NetworkManager::instance().post(
       QString("/networks/%1/streams").arg(networkId), QJsonDocument(body));
-
-  wireReply(reply, op, [this, op, networkId](const QJsonDocument &doc) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this, networkId](const QJsonDocument &doc) {
     if (doc.isObject())
     {
       Stream stream = parseStream(doc.object());
       upsertStream(networkId, stream);
       emit streamsChanged(networkId);
     }
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
 Operation *Store::fetchStream(const QString &streamId)
 {
-  Operation *op = makeOperation();
   QNetworkReply *reply = NetworkManager::instance().get(QString("/streams/%1").arg(streamId));
-
-  wireReply(reply, op, [this, op, streamId](const QJsonDocument &doc) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this, streamId](const QJsonDocument &doc) {
     QJsonObject obj = doc.object();
     Stream stream = parseStream(obj);
 
@@ -574,18 +524,12 @@ Operation *Store::fetchStream(const QString &streamId)
     }
     m_particles[streamId] = particleList;
     emit particlesChanged(streamId);
-
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
 Operation *Store::updateStream(const QString &streamId, const QString &name, const QString &description)
 {
-  Operation *op = makeOperation();
-
   QJsonObject body;
   if (!name.isEmpty())
   {
@@ -598,8 +542,8 @@ Operation *Store::updateStream(const QString &streamId, const QString &name, con
 
   QNetworkReply *reply = NetworkManager::instance().patch(
       QString("/streams/%1").arg(streamId), QJsonDocument(body));
-
-  wireReply(reply, op, [this, op, streamId](const QJsonDocument &doc) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this, streamId](const QJsonDocument &doc) {
     if (doc.isObject())
     {
       Stream stream = parseStream(doc.object());
@@ -610,20 +554,16 @@ Operation *Store::updateStream(const QString &streamId, const QString &name, con
         emit streamsChanged(networkId);
       }
     }
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
 Operation *Store::openStream(const QString &streamId)
 {
-  Operation *op = makeOperation();
   QNetworkReply *reply = NetworkManager::instance().post(
       QString("/streams/%1/open").arg(streamId), QJsonDocument());
-
-  wireReply(reply, op, [this, op, streamId](const QJsonDocument &) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this, streamId](const QJsonDocument &) {
     QString networkId = m_streamToNetwork.value(streamId);
     if (m_networkIndex.contains(networkId))
     {
@@ -638,20 +578,16 @@ Operation *Store::openStream(const QString &streamId)
       }
       emit streamsChanged(networkId);
     }
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
 Operation *Store::closeStream(const QString &streamId)
 {
-  Operation *op = makeOperation();
   QNetworkReply *reply = NetworkManager::instance().post(
       QString("/streams/%1/close").arg(streamId), QJsonDocument());
-
-  wireReply(reply, op, [this, op, streamId](const QJsonDocument &) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this, streamId](const QJsonDocument &) {
     QString networkId = m_streamToNetwork.value(streamId);
     if (m_networkIndex.contains(networkId))
     {
@@ -666,17 +602,12 @@ Operation *Store::closeStream(const QString &streamId)
       }
       emit streamsChanged(networkId);
     }
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
 Operation *Store::addStreamMembers(const QString &streamId, const QStringList &emails)
 {
-  Operation *op = makeOperation();
-
   QJsonObject body;
   QJsonArray arr;
   for (const QString &e : emails)
@@ -687,14 +618,11 @@ Operation *Store::addStreamMembers(const QString &streamId, const QStringList &e
 
   QNetworkReply *reply = NetworkManager::instance().post(
       QString("/streams/%1/members").arg(streamId), QJsonDocument(body));
-  wireReply(reply, op);
-  return op;
+  return new Operation(reply, this);
 }
 
 Operation *Store::removeStreamMembers(const QString &streamId, const QStringList &emails)
 {
-  Operation *op = makeOperation();
-
   QJsonObject body;
   QJsonArray arr;
   for (const QString &e : emails)
@@ -703,8 +631,7 @@ Operation *Store::removeStreamMembers(const QString &streamId, const QStringList
 
   QNetworkReply *reply = NetworkManager::instance().del(
       QString("/streams/%1/members").arg(streamId), QJsonDocument(body));
-  wireReply(reply, op);
-  return op;
+  return new Operation(reply, this);
 }
 
 // ────────────────────────────────────────────────────────────────
@@ -714,8 +641,6 @@ Operation *Store::removeStreamMembers(const QString &streamId, const QStringList
 Operation *Store::createParticle(const QString &streamId, const QString &type,
                                  const QMap<QString, QVariant> &data)
 {
-  Operation *op = makeOperation();
-
   QJsonObject body;
   body["type"] = type;
   QJsonObject dataObj;
@@ -725,27 +650,23 @@ Operation *Store::createParticle(const QString &streamId, const QString &type,
 
   QNetworkReply *reply = NetworkManager::instance().post(
       QString("/streams/%1/particles").arg(streamId), QJsonDocument(body));
-
-  wireReply(reply, op, [this, op, streamId](const QJsonDocument &doc) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this, streamId](const QJsonDocument &doc) {
     if (doc.isObject())
     {
       Particle particle = parseParticle(doc.object());
       upsertParticle(streamId, particle);
       emit particlesChanged(streamId);
     }
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
 Operation *Store::fetchParticle(const QString &particleId)
 {
-  Operation *op = makeOperation();
   QNetworkReply *reply = NetworkManager::instance().get(QString("/particles/%1").arg(particleId));
-
-  wireReply(reply, op, [this, op, particleId](const QJsonDocument &doc) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this, particleId](const QJsonDocument &doc) {
     if (doc.isObject())
     {
       Particle particle = parseParticle(doc.object());
@@ -756,17 +677,12 @@ Operation *Store::fetchParticle(const QString &particleId)
         emit particlesChanged(streamId);
       }
     }
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
 Operation *Store::updateParticle(const QString &particleId, const QMap<QString, QVariant> &data)
 {
-  Operation *op = makeOperation();
-
   QJsonObject body;
   QJsonObject dataObj;
   for (auto it = data.constBegin(); it != data.constEnd(); ++it)
@@ -775,8 +691,8 @@ Operation *Store::updateParticle(const QString &particleId, const QMap<QString,
 
   QNetworkReply *reply = NetworkManager::instance().patch(
       QString("/particles/%1").arg(particleId), QJsonDocument(body));
-
-  wireReply(reply, op, [this, op, particleId](const QJsonDocument &doc) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this, particleId](const QJsonDocument &doc) {
     if (doc.isObject())
     {
       Particle particle = parseParticle(doc.object());
@@ -787,27 +703,20 @@ Operation *Store::updateParticle(const QString &particleId, const QMap<QString,
         emit particlesChanged(streamId);
       }
     }
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
 Operation *Store::deleteParticle(const QString &particleId)
 {
-  Operation *op = makeOperation();
   QNetworkReply *reply = NetworkManager::instance().del(QString("/particles/%1").arg(particleId));
-
-  wireReply(reply, op, [this, op, particleId](const QJsonDocument &) {
+  auto *op = new Operation(reply, this);
+  connect(op, &Operation::success, this, [this, particleId](const QJsonDocument &) {
     QString streamId = findStreamForParticle(particleId);
     removeParticleFromState(particleId);
     if (!streamId.isEmpty())
       emit particlesChanged(streamId);
-    emit op->success();
-    emit op->finished();
   });
-
   return op;
 }
 
@@ -818,20 +727,36 @@ Operation *Store::markParticleSeen(const QString &particleId)
   {
     for (int i = 0; i < it.value().size(); ++i)
     {
-      if (it.value()[i].id == particleId)
+      if (it.value()[i].id == particleId && !it.value()[i].seen)
       {
         it.value()[i].seen = true;
-        emit particlesChanged(it.key());
+        QString streamId = it.key();
+
+        // Decrement the parent stream's unseen count
+        QString networkId = m_streamToNetwork.value(streamId);
+        if (m_networkIndex.contains(networkId))
+        {
+          auto &streams = m_networks[m_networkIndex[networkId]].streams;
+          for (auto &s : streams)
+          {
+            if (s.id == streamId && s.unseenCount > 0)
+            {
+              s.unseenCount--;
+              break;
+            }
+          }
+        }
+
+        emit particleUpdated(streamId, particleId);
+        emit streamUpdated(streamId);
         break;
       }
     }
   }
 
-  Operation *op = makeOperation();
   QNetworkReply *reply = NetworkManager::instance().post(
       QString("/particles/%1/seen").arg(particleId), QJsonDocument());
-  wireReply(reply, op);
-  return op;
+  return new Operation(reply, this);
 }
 
 Operation *Store::markParticlesSeen(const QStringList &particleIds)
@@ -856,8 +781,6 @@ Operation *Store::markParticlesSeen(const QStringList &particleIds)
   for (const QString &streamId : affectedStreams)
     emit particlesChanged(streamId);
 
-  Operation *op = makeOperation();
-
   QJsonObject body;
   QJsonArray ids;
   for (const QString &id : particleIds)
@@ -865,15 +788,12 @@ Operation *Store::markParticlesSeen(const QStringList &particleIds)
   body["particle_ids"] = ids;
 
   QNetworkReply *reply = NetworkManager::instance().post("/particles/seen", QJsonDocument(body));
-  wireReply(reply, op);
-  return op;
+  return new Operation(reply, this);
 }
 
 Operation *Store::ackParticle(const QString &particleId)
 {
-  Operation *op = makeOperation();
   QNetworkReply *reply = NetworkManager::instance().post(
       QString("/particles/%1/ack").arg(particleId), QJsonDocument());
-  wireReply(reply, op);
-  return op;
+  return new Operation(reply, this);
 }
diff --git a/src/store.h b/src/store.h
index 4b40109..7c74128 100644
--- a/src/store.h
+++ b/src/store.h
@@ -6,21 +6,22 @@
 #include <QMap>
 
 QT_BEGIN_NAMESPACE
+class QJsonDocument;
 class QNetworkReply;
 QT_END_NAMESPACE
 
 /// Represents an in-flight API operation.
-/// Callers connect to success/failed for one-off feedback.
+/// Wraps a QNetworkReply: owns cleanup, parses JSON, and emits signals.
 /// Automatically deletes itself after finished() fires.
 class Operation : public QObject
 {
   Q_OBJECT
 
 public:
-  explicit Operation(QObject *parent = nullptr);
+  explicit Operation(QNetworkReply *reply, QObject *parent = nullptr);
 
 signals:
-  void success();
+  void success(const QJsonDocument &response);
   void failed(const QString &message);
   void finished();
 };
@@ -91,6 +92,10 @@ signals:
   void streamsChanged(const QString &networkId);
   void particlesChanged(const QString &streamId);
 
+  // Granular signals for in-place property updates (no structural change)
+  void particleUpdated(const QString &streamId, const QString &particleId);
+  void streamUpdated(const QString &streamId);
+
   void startupDataLoaded();
   void errorOccurred(const QString &message);
 
@@ -120,20 +125,6 @@ private:
   /// Returns the streamId that contains the given particle, or empty QString.
   QString findStreamForParticle(const QString &particleId) const;
 
-  // ── Operation helpers ──
-
-  /// Creates an Operation parented to this Store, wired to self-destruct after finished().
-  Operation *makeOperation();
-
-  /// Connects reply->finished to a handler. On error, emits op->failed + op->finished.
-  /// On success, calls successHandler with the parsed QJsonDocument.
-  /// successHandler is responsible for emitting op->success() and op->finished().
-  void wireReply(QNetworkReply *reply, Operation *op,
-                 std::function<void(const QJsonDocument &)> successHandler);
-
-  /// Simplified wireReply for operations that don't need to parse a response body
-  /// (e.g. 204 No Content). Emits op->success() and op->finished() automatically.
-  void wireReply(QNetworkReply *reply, Operation *op);
 };
 
 #endif // STORE_H