feat(worker): load a thread as a reply tree with per-message depth

loadThread could not be extended to do this. It walks
notmuch_query_search_messages, and a message obtained that way returns NULL from
notmuch_message_get_replies (notmuch.h:1617-1628), so that walk cannot produce
reply depth at all. The tree comes from notmuch_thread_get_toplevel_messages
instead, and the pane keeps the flat list it wants.

walkReplies takes raw notmuch_message_t*, against this file's rule that every
handle is RAII-owned. Messages reached through a thread are freed with it
(notmuch.h:1637), so an NmMessage wrapper would destroy memory the thread frees
again. The NmThread in the caller is what keeps them alive.

Every message in the thread gets a node regardless of the query: the list is
where the reply count is read, and hiding unmatched replies would make that
count disagree with the rows under it.

Both tests mutation-checked. Flattening depth fails the depth assertion, and
skipping the thread walk fails it too, so neither passes against the two
mistakes the notmuch API invites.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/mainwindow.cpp b/src/mainwindow.cpp
index 11de1d4..13406e4 100644
--- a/src/mainwindow.cpp
+++ b/src/mainwindow.cpp
@@ -289,8 +289,10 @@ MainWindow::MainWindow(const Config &config, QWidget *parent)
     qRegisterMetaType<MessageRef>();
     qRegisterMetaType<TagChange>();
     qRegisterMetaType<DatabaseStats>();
+    qRegisterMetaType<MessageNode>();
     qRegisterMetaType<QVector<ThreadSummary>>();
     qRegisterMetaType<QVector<MessageRef>>();
+    qRegisterMetaType<QVector<MessageNode>>();
 
     m_keyMap.loadDefaults();
     {