Fix index used by LocalDocs when tool calling/thinking is active (#3451)

Signed-off-by: Jared Van Bortel <jared@nomic.ai>

gpt4all-chat/CHANGELOG.md

@@ -4,6 +4,11 @@ All notable changes to this project will be documented in this file.
 
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 
+## [Unreleased]
+
+### Fixed
+- Fix "index N is not a prompt" when using LocalDocs with reasoning ([#3451](https://github.com/nomic-ai/gpt4all/pull/3451)
+
 ## [3.8.0] - 2025-01-30
 
 ### Added
@@ -283,6 +288,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 - Fix several Vulkan resource management issues ([#2694](https://github.com/nomic-ai/gpt4all/pull/2694))
 - Fix crash/hang when some models stop generating, by showing special tokens ([#2701](https://github.com/nomic-ai/gpt4all/pull/2701))
 
+[Unreleased]: https://github.com/nomic-ai/gpt4all/compare/v3.8.0...HEAD
 [3.8.0]: https://github.com/nomic-ai/gpt4all/compare/v3.7.0...v3.8.0
 [3.7.0]: https://github.com/nomic-ai/gpt4all/compare/v3.6.1...v3.7.0
 [3.6.1]: https://github.com/nomic-ai/gpt4all/compare/v3.6.0...v3.6.1

gpt4all-chat/src/chatllm.cpp

@@ -730,7 +730,8 @@ std::vector<MessageItem> ChatLLM::forkConversation(const QString &prompt) const
         conversation.reserve(items.size() + 1);
         conversation.assign(items.begin(), items.end());
     }
-    conversation.emplace_back(MessageItem::Type::Prompt, prompt.toUtf8());
+    qsizetype nextIndex = conversation.empty() ? 0 : conversation.back().index().value() + 1;
+    conversation.emplace_back(nextIndex, MessageItem::Type::Prompt, prompt.toUtf8());
     return conversation;
 }
 
@@ -801,7 +802,7 @@ std::string ChatLLM::applyJinjaTemplate(std::span<const MessageItem> items) cons
     json::array_t messages;
     messages.reserve(useSystem + items.size());
     if (useSystem) {
-        systemItem = std::make_unique<MessageItem>(MessageItem::Type::System, systemMessage.toUtf8());
+        systemItem = std::make_unique<MessageItem>(MessageItem::system_tag, systemMessage.toUtf8());
         messages.emplace_back(makeMap(*systemItem));
     }
     for (auto &item : items)
@@ -855,14 +856,14 @@ auto ChatLLM::promptInternalChat(const QStringList &enabledCollections, const LL
             // Find the prompt that represents the query. Server chats are flexible and may not have one.
             auto items = getChat();
             if (auto peer = m_chatModel->getPeer(items, items.end() - 1)) // peer of response
-                query = { *peer - items.begin(), (*peer)->content() };
+                query = { (*peer)->index().value(), (*peer)->content() };
         }
 
         if (query) {
             auto &[promptIndex, queryStr] = *query;
             const int retrievalSize = MySettings::globalInstance()->localDocsRetrievalSize();
             emit requestRetrieveFromDB(enabledCollections, queryStr, retrievalSize, &databaseResults); // blocks
-            m_chatModel->updateSources(promptIndex + startOffset, databaseResults);
+            m_chatModel->updateSources(promptIndex, databaseResults);
             emit databaseResultsChanged(databaseResults);
         }
     }

gpt4all-chat/src/chatmodel.h

@@ -94,11 +94,28 @@ class MessageItem
 public:
     enum class Type { System, Prompt, Response, ToolResponse };
 
-    MessageItem(Type type, QString content)
+    struct system_tag_t { explicit system_tag_t() = default; };
-        : m_type(type), m_content(std::move(content)) {}
+    static inline constexpr system_tag_t system_tag = system_tag_t{};
 
-    MessageItem(Type type, QString content, const QList<ResultInfo> &sources, const QList<PromptAttachment> &promptAttachments)
+    MessageItem(qsizetype index, Type type, QString content)
-        : m_type(type), m_content(std::move(content)), m_sources(sources), m_promptAttachments(promptAttachments) {}
+        : m_index(index), m_type(type), m_content(std::move(content))
+    {
+        Q_ASSERT(type != Type::System); // use system_tag constructor
+    }
+
+    // Construct a system message with no index, since they are never stored in the chat
+    MessageItem(system_tag_t, QString content)
+        : m_type(Type::System), m_content(std::move(content)) {}
+
+    MessageItem(qsizetype index, Type type, QString content, const QList<ResultInfo> &sources, const QList<PromptAttachment> &promptAttachments)
+        : m_index(index)
+        , m_type(type)
+        , m_content(std::move(content))
+        , m_sources(sources)
+        , m_promptAttachments(promptAttachments) {}
+
+    // index of the parent ChatItem (system, prompt, response) in its container
+    std::optional<qsizetype> index()   const { return m_index; }
 
     Type           type()    const { return m_type;    }
     const QString &content() const { return m_content; }
@@ -126,6 +143,7 @@ public:
     }
 
 private:
+    std::optional<qsizetype> m_index;
     Type                     m_type;
     QString                  m_content;
     QList<ResultInfo>        m_sources;
@@ -399,7 +417,7 @@ public:
         Q_UNREACHABLE();
     }
 
-    MessageItem asMessageItem() const
+    MessageItem asMessageItem(qsizetype index) const
     {
         MessageItem::Type msgType;
         switch (auto typ = type()) {
@@ -413,7 +431,7 @@ public:
             case Think:
                 throw std::invalid_argument(fmt::format("cannot convert ChatItem type {} to message item", int(typ)));
         }
-        return { msgType, flattenedContent(), sources, promptAttachments };
+        return { index, msgType, flattenedContent(), sources, promptAttachments };
     }
 
     static QList<ResultInfo> consolidateSources(const QList<ResultInfo> &sources);
@@ -537,6 +555,7 @@ private:
         return std::nullopt;
     }
 
+    // FIXME(jared): this should really be done at the parent level, not the sub-item level
     static std::optional<qsizetype> getPeerInternal(const MessageItem *arr, qsizetype size, qsizetype index)
     {
         qsizetype peer;
@@ -1114,10 +1133,12 @@ public:
         // A flattened version of the chat item tree used by the backend and jinja
         QMutexLocker locker(&m_mutex);
         std::vector<MessageItem> chatItems;
-        for (const ChatItem *item : m_chatItems) {
+        for (qsizetype i : views::iota(0, m_chatItems.size())) {
-            chatItems.reserve(chatItems.size() + item->subItems.size() + 1);
+            auto *parent = m_chatItems.at(i);
-            ranges::copy(item->subItems | views::transform(&ChatItem::asMessageItem), std::back_inserter(chatItems));
+            chatItems.reserve(chatItems.size() + parent->subItems.size() + 1);
-            chatItems.push_back(item->asMessageItem());
+            ranges::copy(parent->subItems | views::transform([&](auto *s) { return s->asMessageItem(i); }),
+                         std::back_inserter(chatItems));
+            chatItems.push_back(parent->asMessageItem(i));
         }
         return chatItems;
     }