fix(drafts): index a saved draft so it appears without a sync

Autosave writes the draft to the Maildir drafts folder and stops, while
the Drafts view is a notmuch path: query, so a freshly saved draft was
invisible until notmuch new ran. saveDraftNow() now emits draftSaved, and
MainWindow connects it to a new NotmuchWorker::indexDraftFile() that
indexes the one file the way moveMessages() does, with the previous
revision removed so a rewrite leaves no ghost.

The send path unlinks a draft that was indexed while being composed, so
draftRemoved -> removeIndexedFile() drops its entry too.

Measured: notmuch_database_index_file assigns NO tags (unlike notmuch
new, which adds draft inbox unread), so no tag-stripping is needed and the
draft cannot leak into a tag:inbox view.

Item 158.

1 files changed, 22 insertions, 0 deletions

diff --git a/src/notmuchworker.h b/src/notmuchworker.h
index 8ed878f..3ccf8e5 100644
--- a/src/notmuchworker.h
+++ b/src/notmuchworker.h
@@ -134,6 +134,28 @@ public slots:
     /// it, so removing before indexing loses the message's tags.
     void moveMessages(const QStringList &messageIds, const QString &destFolder);
 
+    /// Indexes one freshly written file, so it appears in a `path:` query
+    /// without a full `notmuch new` (item 158).
+    ///
+    /// The draft-save path writes the file and stops, and the Drafts view is a
+    /// path query, so an unindexed draft is invisible until the next sync. A
+    /// draft rewrite writes a NEW file (MessageBuilder generates a fresh
+    /// Message-ID on every build) and unlinks the old, so \p previousPath is
+    /// removed after the new one is indexed, mirroring moveMessages()'s
+    /// ordering: the old entry must not linger as a ghost draft.
+    ///
+    /// \p path is absolute, as DraftStore::write() returns it. The Maildir
+    /// flags on the file (the "D" flag a draft carries) drive its tags exactly
+    /// as they would on a later `notmuch new`.
+    void indexDraftFile(const QString &path, const QString &previousPath = {});
+
+    /// Removes one file from the index, without touching the file on disk.
+    ///
+    /// The counterpart to indexDraftFile() for the send path: a draft that was
+    /// indexed while being composed is unlinked when it is sent, and its entry
+    /// must not linger as a ghost draft until the next sync.
+    void removeIndexedFile(const QString &path);
+
     /// Batch tagging over whole threads. The UI holds thread ids, not message
     /// ids, for rows it has not opened, so the resolution happens here where
     /// the database handle lives. This is the path the archive/flag/delete