feat: add the thread dashboard

A widget over a ThreadDigest: header, tags, counts, the unread list capped
with a link to the rest, and an activity sparkline, scrolling under a pinned
action strip. It invents no colours.

ThreadDigest::unread is QVector<MessageNode> rather than QVector<MessageRef>.
The dashboard draws rows for messages it never opens, which is what
MessageNode exists for; MessageRef carries only what the pane needs once a
message is already open and has no subject, sender or date. The struct's
no-file-opening contract still holds, since all four of those fields are
served from the notmuch index.

2 files changed, 75 insertions, 0 deletions

diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 1646028..e67d7e0 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -72,6 +72,7 @@ add_qtmaildir_test(searchterm)
 add_qtmaildir_test(signatures)
 add_qtmaildir_test(busyindicator)
 add_qtmaildir_test(tagstrip)
+add_qtmaildir_test(threaddashboard)
 add_qtmaildir_test(messagedetailsdialog)
 add_qtmaildir_test(markdownrenderer)
 add_qtmaildir_test(messagebuilder)
diff --git a/tests/test_threaddashboard.cpp b/tests/test_threaddashboard.cpp
new file mode 100644
index 0000000..66f187f
--- /dev/null
+++ b/tests/test_threaddashboard.cpp
@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+ */
+#include <QtTest>
+
+#include "threaddashboard.h"
+#include "threaddigest.h"
+
+class TestThreadDashboard : public QObject
+{
+    Q_OBJECT
+
+private slots:
+    void itNamesTheUnreadCountItWasGiven();
+    void itSaysAllCaughtUpWhenNothingIsUnread();
+    void itOffersMoreWhenTheListIsCapped();
+    void itOffersNoMoreLinkWhenTheListIsComplete();
+};
+
+static ThreadDigest digestWith(int unreadTotal, int shown)
+{
+    ThreadDigest d;
+    d.threadId = QStringLiteral("t1");
+    d.totalCount = 44;
+    d.unreadTotal = unreadTotal;
+    for (int i = 0; i < shown; ++i) {
+        MessageNode ref;
+        ref.messageId = QStringLiteral("m%1@example.org").arg(i);
+        ref.subject = QStringLiteral("Re: something");
+        // The avatar hashes the bare address, so a node without one exercises
+        // only the no-sender fallback.
+        ref.senderAddress = QStringLiteral("someone@example.org");
+        d.unread.append(ref);
+    }
+    d.buckets = QVector<int>(ThreadDigest::kBuckets, 1);
+    return d;
+}
+
+void TestThreadDashboard::itNamesTheUnreadCountItWasGiven()
+{
+    ThreadDashboard dashboard;
+    dashboard.setDigest(digestWith(3, 3));
+    QCOMPARE(dashboard.unreadCountShown(), 3);
+    QVERIFY(!dashboard.showingAllCaughtUp());
+}
+
+void TestThreadDashboard::itSaysAllCaughtUpWhenNothingIsUnread()
+{
+    ThreadDashboard dashboard;
+    dashboard.setDigest(digestWith(0, 0));
+    QVERIFY2(dashboard.showingAllCaughtUp(),
+             "a fully read thread shows an empty Waiting for you block rather "
+             "than saying so");
+}
+
+void TestThreadDashboard::itOffersMoreWhenTheListIsCapped()
+{
+    // 20 unread, 5 shown: the link has to name the 15 the pane cannot list, or
+    // the dashboard under-reports exactly when the number matters most.
+    ThreadDashboard dashboard;
+    dashboard.setDigest(digestWith(20, ThreadDigest::kUnreadShown));
+    QCOMPARE(dashboard.hiddenUnreadCount(), 15);
+}
+
+void TestThreadDashboard::itOffersNoMoreLinkWhenTheListIsComplete()
+{
+    ThreadDashboard dashboard;
+    dashboard.setDigest(digestWith(4, 4));
+    QCOMPARE(dashboard.hiddenUnreadCount(), 0);
+}
+
+QTEST_MAIN(TestThreadDashboard)
+#include "test_threaddashboard.moc"