better chat list view + anchor to bottom. sqlite db for chats + LIFO-ordered

Plugins/ZShell/Llm/messagemodel.hpp

@@ -0,0 +1,68 @@
+#pragma once
+
+#include "message.hpp"
+
+#include <QAbstractListModel>
+#include <QHash>
+#include <QList>
+#include <QtQml>
+#include <qtmetamacros.h>
+
+namespace ZShell::llm {
+
+class ChatSession;
+
+// Owns a session's messages, most recent first: row 0 is always the newest
+// message. Items are exposed through a role named "modelData" (like
+// FileSystemModel), so delegates receive each ChatMessage as `modelData`.
+class ChatMessageModel : public QAbstractListModel {
+	Q_OBJECT
+	QML_ELEMENT
+	QML_UNCREATABLE("Chat message models are owned by ChatSession")
+
+	Q_PROPERTY(
+		ZShell::llm::ChatMessage* lastMessage READ lastMessage
+			NOTIFY lastMessageChanged)
+
+	public:
+	explicit ChatMessageModel(ChatSession* session, QObject* parent = nullptr);
+	~ChatMessageModel() override;
+
+	[[nodiscard]] int rowCount(
+		const QModelIndex& parent = QModelIndex()) const override;
+	[[nodiscard]] QVariant data(
+		const QModelIndex& index, int role = Qt::DisplayRole) const override;
+	[[nodiscard]] QHash<int, QByteArray> roleNames() const override;
+
+	[[nodiscard]] ChatSession* session() const { return m_session; }
+	// Most recent message first.
+	[[nodiscard]] QList<ChatMessage*> messages() const { return m_messages; }
+	[[nodiscard]] ChatMessage* at(int row) const;
+	[[nodiscard]] int rowOf(const ChatMessage* message) const;
+
+	[[nodiscard]] ChatMessage* lastMessage() const {
+		return m_messages.isEmpty() ? nullptr : m_messages.first();
+	}
+
+	// Creates a message owned by this model without inserting it.
+	ChatMessage* createMessage(ChatMessage::Role role, qint64 timestamp);
+	// Appends a new message as the newest one (row 0) with a single
+	// generation holding `content`.
+	ChatMessage* appendNewest(
+		ChatMessage::Role role, const QString& content, qint64 timestamp);
+	void removeMessage(ChatMessage* message);
+	void removeRange(int firstRow, int lastRow);
+	void clear();
+	// Replaces every row; takes ownership of the given messages, most recent
+	// first.
+	void loadMessages(QList<ChatMessage*> messages);
+
+	signals:
+	void lastMessageChanged();
+
+	private:
+	ChatSession* m_session;
+	QList<ChatMessage*> m_messages;
+};
+
+} // namespace ZShell::llm