feat: add support code completion via acp

sources/completion/AcpCompletionEngine.hpp

@@ -0,0 +1,86 @@
+// Copyright (C) 2026 Petr Mironychev
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Additional attribution terms under GPLv3 §7(b) apply — see LICENSE
+
+#pragma once
+
+#include <functional>
+#include <optional>
+
+#include <QString>
+
+#include <LLMQore/AcpPermissionProvider.hpp>
+
+#include "acp/AgentDefinition.hpp"
+#include "acp/AgentSpawn.hpp"
+#include "completion/CompletionEngine.hpp"
+#include "context/IDocumentReader.hpp"
+#include "mcp/CompletionMcpServer.hpp"
+#include "settings/CodeCompletionSettings.hpp"
+#include "settings/GeneralSettings.hpp"
+#include "tools/ProposeCompletionTool.hpp"
+
+namespace QodeAssist {
+
+class AcpCompletionEngine : public CompletionEngine
+{
+    Q_OBJECT
+
+public:
+    using ClientFactory = std::function<
+        Acp::AgentProcess(const Acp::AgentDefinition &agent, const QString &cwd, QObject *parent)>;
+    using AgentResolver = std::function<std::optional<Acp::AgentDefinition>(const QString &id)>;
+
+    AcpCompletionEngine(
+        const Settings::CodeCompletionSettings &completeSettings,
+        const Settings::GeneralSettings &generalSettings,
+        AgentResolver agentResolver,
+        Context::IDocumentReader &documentReader,
+        Tools::ProposeCompletionTool *proposeTool,
+        QObject *parent = nullptr);
+
+    void setClientFactory(ClientFactory factory);
+
+    void request(quint64 requestId, const CompletionContext &context) override;
+    void cancel(quint64 requestId) override;
+
+    bool hasConfiguredAgent() const;
+
+private slots:
+    void handleCompletionProposed(
+        const QString &filePath, int line, int column, const QString &text);
+
+private:
+    struct ActiveRequest
+    {
+        quint64 requestId = 0;
+        QString filePath;
+        int line = 0;
+        int column = 0;
+        QString codeContext;
+    };
+
+    void ensureClientAndPrompt();
+    void sendPrompt();
+    void failActive(const QString &error);
+    void releaseClient();
+    QString promptText() const;
+
+    const Settings::CodeCompletionSettings &m_completeSettings;
+    const Settings::GeneralSettings &m_generalSettings;
+    AgentResolver m_agentResolver;
+    Context::IDocumentReader &m_documentReader;
+    Tools::ProposeCompletionTool *m_proposeTool = nullptr;
+    ClientFactory m_clientFactory;
+    Mcp::CompletionMcpServer *m_completionServer = nullptr;
+    LLMQore::Acp::AcpPermissionProvider *m_permissions = nullptr;
+
+    LLMQore::Acp::AcpClient *m_client = nullptr;
+    QString m_boundAgentId;
+    QString m_sessionId;
+    int m_clientGeneration = 0;
+    bool m_sessionReady = false;
+    std::optional<ActiveRequest> m_active;
+};
+
+} // namespace QodeAssist