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+/*
+ * qtmaildir - a Qt6 mail client for notmuch-indexed Maildirs
+ * Copyright (C) 2026 Danilo M. <danix@danix.xyz>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#pragma once
+
+#include <QHash>
+#include <QSet>
+#include <QString>
+#include <QStringList>
+
+/// The list of senders that read as businesses rather than people.
+///
+/// `~/.config/qtmaildir/business-senders`, plain text, one entry per line,
+/// `#` comments, blank lines ignored. Deliberately NOT in qtmaildir.conf and
+/// deliberately not INI: the user's stated workflow is grep-and-edit, QSettings
+/// would fight a bare list, and the main config is already large.
+///
+/// An entry is an exact address (`noreply@cofidis.it`) or a whole domain
+/// (`@cofidis.it`). No globs: a pattern language is a rule the user cannot grep
+/// for literally, which defeats the file's purpose.
+namespace BusinessSenders
+{
+
+/// Parsed entries, lower-cased. Two sets rather than one list so a lookup is a
+/// hash probe per repaint rather than a walk.
+struct List
+{
+    QSet<QString> addresses;
+    QSet<QString> domains;   ///< Stored WITHOUT the leading '@'.
+};
+
+List parse(const QString &contents);
+
+/// Reads `path`. A missing or unreadable file yields an empty list rather than
+/// an error: the feature is cosmetic and must never block startup.
+List load(const QString &path);
+
+bool contains(const List &list, const QString &address);
+
+/// `~/.config/qtmaildir/business-senders`, built from
+/// QStandardPaths::GenericConfigLocation.
+QString defaultPath();
+
+/// True when a local part looks like bulk mail rather than a person.
+///
+/// A GUESS, and openly one. It misses senders and proposes wrong ones, which
+/// is exactly why nothing it produces takes effect until the user uncomments
+/// it.
+bool looksLikeBulk(const QString &address);
+
+/// Appends anything in `counts` that looks like bulk and is not already in the
+/// file, COMMENTED OUT, with its message count.
+///
+/// Two rules, both load-bearing. It never writes an uncommented entry, so
+/// nothing on screen changes until the user acts. And it skips an address
+/// already present in ANY form, commented or not, so an entry the user
+/// rejected is never re-proposed, and one they deleted only returns if that
+/// sender writes again.
+void appendCandidates(const QString &path, const QHash<QString, int> &counts);
+
+/// The query the candidate scan should run.
+///
+/// A week of mail once the file exists, so the step stays incremental and
+/// cheap. EVERYTHING when the file is missing or holds no entries, because
+/// that is the first run: a week's mail proposes almost nothing, and the file
+/// would then take months to become useful. The whole-database scan is
+/// affordable precisely because it happens once, measured at 76 ms over 5105
+/// messages.
+///
+/// Returns notmuch query syntax, which is wire format and is never translated.
+QString scanQuery(const QString &path);
+
+} // namespace BusinessSenders