diff --git a/src/plugins/clangcodemodel/clangdcompletion.cpp b/src/plugins/clangcodemodel/clangdcompletion.cpp
index dc5feccf037..8b7799e8684 100644
--- a/src/plugins/clangcodemodel/clangdcompletion.cpp
+++ b/src/plugins/clangcodemodel/clangdcompletion.cpp
@@ -81,7 +81,9 @@ private:
 class ClangdCompletionAssistProcessor : public LanguageClientCompletionAssistProcessor
 {
 public:
-    ClangdCompletionAssistProcessor(ClangdClient *client, const QString &snippetsGroup);
+    ClangdCompletionAssistProcessor(ClangdClient *client,
+                                    const IAssistProvider *provider,
+                                    const QString &snippetsGroup);
     ~ClangdCompletionAssistProcessor();
 
 private:
@@ -164,7 +166,7 @@ IAssistProcessor *ClangdCompletionAssistProvider::createProcessor(
                                       : QString();
     qCDebug(clangdLogCompletion) << "creating proper completion processor"
                                  << (snippetsGroup.isEmpty() ? "without" : "with") << "snippets";
-    return new ClangdCompletionAssistProcessor(m_client, snippetsGroup);
+    return new ClangdCompletionAssistProcessor(m_client, this, snippetsGroup);
 }
 
 bool ClangdCompletionAssistProvider::isActivationCharSequence(const QString &sequence) const
@@ -554,8 +556,9 @@ QList<AssistProposalItemInterface *> CustomAssistProcessor::completeIncludePath(
 }
 
 ClangdCompletionAssistProcessor::ClangdCompletionAssistProcessor(ClangdClient *client,
+                                                                 const IAssistProvider *provider,
                                                                  const QString &snippetsGroup)
-    : LanguageClientCompletionAssistProcessor(client, snippetsGroup)
+    : LanguageClientCompletionAssistProcessor(client, provider, snippetsGroup)
     , m_client(client)
 {
     m_timer.start();
diff --git a/src/plugins/cppeditor/cppvirtualfunctionassistprovider.cpp b/src/plugins/cppeditor/cppvirtualfunctionassistprovider.cpp
index 8b47f7fe5b3..575c3b93952 100644
--- a/src/plugins/cppeditor/cppvirtualfunctionassistprovider.cpp
+++ b/src/plugins/cppeditor/cppvirtualfunctionassistprovider.cpp
@@ -42,6 +42,7 @@ public:
             : TextEditor::Constants::FOLLOW_SYMBOL_UNDER_CURSOR;
         if (Core::Command *command = Core::ActionManager::command(id))
             m_sequence = command->keySequence();
+        setFragile(true);
     }
 
 protected:
@@ -169,9 +170,7 @@ IAssistProcessor *VirtualFunctionAssistProvider::createProcessor(const AssistInt
 VirtualFunctionProposal::VirtualFunctionProposal(
         int cursorPos, const QList<AssistProposalItemInterface *> &items, bool openInSplit)
     : GenericProposal(cursorPos, items), m_openInSplit(openInSplit)
-{
-    setFragile(true);
-}
+{ }
 
 IAssistProposalWidget *VirtualFunctionProposal::createWidget() const
 {
diff --git a/src/plugins/languageclient/languageclientcompletionassist.cpp b/src/plugins/languageclient/languageclientcompletionassist.cpp
index 2762e2b32e7..afee00a5acc 100644
--- a/src/plugins/languageclient/languageclientcompletionassist.cpp
+++ b/src/plugins/languageclient/languageclientcompletionassist.cpp
@@ -11,6 +11,7 @@
 #include <texteditor/codeassist/assistinterface.h>
 #include <texteditor/codeassist/genericproposal.h>
 #include <texteditor/codeassist/genericproposalmodel.h>
+#include <texteditor/codeassist/genericproposalwidget.h>
 #include <texteditor/snippets/snippet.h>
 #include <texteditor/snippets/snippetassistcollector.h>
 #include <texteditor/textdocument.h>
@@ -224,6 +225,13 @@ public:
     bool supportsPrefixExpansion() const override { return false; }
 
     QList<AssistProposalItemInterface *> items() const { return m_currentItems; }
+
+    bool isComplete(const QString prefix)
+    { return m_completePrefix && prefix.startsWith(*m_completePrefix); }
+    void setCompletePrefix(const QString &completePrefix) { m_completePrefix = completePrefix; }
+
+private:
+    std::optional<QString> m_completePrefix;
 };
 
 bool LanguageClientCompletionModel::isSortable(const QString &) const
@@ -252,13 +260,85 @@ void LanguageClientCompletionModel::sort(const QString &prefix)
     });
 }
 
+class LanguageClientCompletionWidget : public GenericProposalWidget
+{
+public:
+    LanguageClientCompletionWidget(const IAssistProvider *provider)
+        : m_provider(provider)
+    {}
+
+    ~LanguageClientCompletionWidget() { deleteCurrentProcessor(); }
+
+    void deleteCurrentProcessor()
+    {
+        if (m_processor) {
+            m_processor->cancel();
+            delete m_processor;
+            m_processor = nullptr;
+        }
+    }
+
+    bool isComplete(const AssistInterface *interface)
+    {
+        const QString prefix = interface->textAt(basePosition(),
+                                                 interface->position() - basePosition());
+        return static_cast<LanguageClientCompletionModel *>(model().data())->isComplete(prefix);
+    }
+
+    void setProposal(IAssistProposal *proposal)
+    {
+        if (!proposal)
+            return;
+        updateModel(proposal->model());
+        delete proposal;
+    }
+
+    void updateProposal(std::unique_ptr<AssistInterface> &&interface) override
+    {
+        deleteCurrentProcessor();
+        if (!m_provider || isComplete(interface.get())) {
+            GenericProposalWidget::updateProposal(std::move(interface));
+            return;
+        }
+        auto processor = m_provider->createProcessor(interface.get());
+        QTC_ASSERT(processor, return);
+
+        processor->setAsyncCompletionAvailableHandler([this, processor](IAssistProposal *proposal) {
+            QTC_ASSERT(processor == m_processor, return);
+            if (!processor->running()) {
+                // do not delete this processor directly since this function is called from within the processor
+                QMetaObject::invokeMethod(
+                    QCoreApplication::instance(),
+                    [processor] { delete processor; },
+                    Qt::QueuedConnection);
+                m_processor = nullptr;
+            }
+            setProposal(proposal);
+        });
+
+        setProposal(processor->start(std::move(interface)));
+        if (processor->running())
+            m_processor = processor;
+        else
+            delete processor;
+    }
+
+private:
+    QPointer<const IAssistProvider> m_provider;
+    std::optional<MessageId> m_currentRequestId;
+    IAssistProcessor *m_processor = nullptr;
+};
+
 class LanguageClientCompletionProposal : public GenericProposal
 {
 public:
-    LanguageClientCompletionProposal(int cursorPos, LanguageClientCompletionModel *model)
+    LanguageClientCompletionProposal(const IAssistProvider *provider,
+                                     int cursorPos,
+                                     LanguageClientCompletionModel *model)
         : GenericProposal(cursorPos, GenericProposalModelPtr(model))
         , m_model(model)
-    { }
+        , m_provider(provider)
+    {}
 
     // IAssistProposal interface
     bool hasItemsToPropose(const QString &/*text*/, AssistReason reason) const override
@@ -274,15 +354,21 @@ public:
         });
     }
 
+    IAssistProposalWidget *createWidget() const override
+    {
+        return new LanguageClientCompletionWidget(m_provider);
+    }
+
     LanguageClientCompletionModel *m_model;
     QPointer<QTextDocument> m_document;
+    QPointer<const IAssistProvider> m_provider;
     int m_pos = -1;
 };
 
 LanguageClientCompletionAssistProcessor::LanguageClientCompletionAssistProcessor(
-    Client *client,
-    const QString &snippetsGroup)
+    Client *client, const IAssistProvider *provider, const QString &snippetsGroup)
     : m_client(client)
+    , m_provider(provider)
     , m_snippetsGroup(snippetsGroup)
 {}
 
@@ -409,32 +495,36 @@ void LanguageClientCompletionAssistProcessor::handleCompletionResponse(
         return;
     }
 
+    const QString prefix = Utils::Text::textAt(QTextCursor(document()),
+                                               m_basePos,
+                                               m_pos - m_basePos);
+
     QList<CompletionItem> items;
-    bool isComplete = false;
+    bool isComplete = true;
     if (std::holds_alternative<CompletionList>(*result)) {
         const auto &list = std::get<CompletionList>(*result);
         items = list.items().value_or(QList<CompletionItem>());
-        isComplete = !list.isIncomplete();
+        if (list.isIncomplete())
+            isComplete = false;
     } else if (std::holds_alternative<QList<CompletionItem>>(*result)) {
         items = std::get<QList<CompletionItem>>(*result);
     }
     auto proposalItems = generateCompletionItems(items);
     if (!m_snippetsGroup.isEmpty()) {
-        proposalItems << TextEditor::SnippetAssistCollector(
-                             m_snippetsGroup, QIcon(":/texteditor/images/snippet.png")).collect();
+        proposalItems << TextEditor::SnippetAssistCollector(m_snippetsGroup,
+                                                            QIcon(
+                                                                ":/texteditor/images/snippet.png"))
+                             .collect();
     }
     auto model = new LanguageClientCompletionModel();
     model->loadContent(proposalItems);
-    LanguageClientCompletionProposal *proposal = new LanguageClientCompletionProposal(m_basePos,
+    if (isComplete)
+        model->setCompletePrefix(prefix);
+    LanguageClientCompletionProposal *proposal = new LanguageClientCompletionProposal(m_provider,
+                                                                                      m_basePos,
                                                                                       model);
     proposal->m_document = document();
     proposal->m_pos = m_pos;
-    const QString completePrefix = Utils::Text::textAt(QTextCursor(document()),
-                                                       m_basePos,
-                                                       m_pos - m_basePos);
-    proposal->setPrefixChecker([isComplete, completePrefix](const QString &candidate) {
-        return isComplete && candidate.startsWith(completePrefix);
-    });
     setAsyncProposalAvailable(proposal);
     m_client->removeAssistProcessor(this);
     qCDebug(LOGLSPCOMPLETION) << QTime::currentTime() << " : "
@@ -449,8 +539,7 @@ LanguageClientCompletionAssistProvider::LanguageClientCompletionAssistProvider(C
 IAssistProcessor *LanguageClientCompletionAssistProvider::createProcessor(
     const AssistInterface *) const
 {
-    return new LanguageClientCompletionAssistProcessor(m_client,
-                                                       m_snippetsGroup);
+    return new LanguageClientCompletionAssistProcessor(m_client, this, m_snippetsGroup);
 }
 
 int LanguageClientCompletionAssistProvider::activationCharSequenceLength() const
@@ -460,7 +549,7 @@ int LanguageClientCompletionAssistProvider::activationCharSequenceLength() const
 
 bool LanguageClientCompletionAssistProvider::isActivationCharSequence(const QString &sequence) const
 {
-    return Utils::anyOf(m_triggerChars, [sequence](const QString &trigger){
+    return Utils::anyOf(m_triggerChars, [sequence](const QString &trigger) {
         return trigger.endsWith(sequence);
     });
 }
diff --git a/src/plugins/languageclient/languageclientcompletionassist.h b/src/plugins/languageclient/languageclientcompletionassist.h
index fec5d74072f..b719b2a37d8 100644
--- a/src/plugins/languageclient/languageclientcompletionassist.h
+++ b/src/plugins/languageclient/languageclientcompletionassist.h
@@ -57,7 +57,9 @@ class LANGUAGECLIENT_EXPORT LanguageClientCompletionAssistProcessor
     : public TextEditor::IAssistProcessor
 {
 public:
-    LanguageClientCompletionAssistProcessor(Client *client, const QString &snippetsGroup);
+    LanguageClientCompletionAssistProcessor(Client *client,
+                                            const TextEditor::IAssistProvider *provider,
+                                            const QString &snippetsGroup);
     ~LanguageClientCompletionAssistProcessor() override;
     TextEditor::IAssistProposal *perform() override;
     bool running() override;
@@ -76,6 +78,7 @@ private:
 
     Utils::FilePath m_filePath;
     QPointer<Client> m_client;
+    QPointer<const TextEditor::IAssistProvider> m_provider;
     std::optional<LanguageServerProtocol::MessageId> m_currentRequest;
     QMetaObject::Connection m_postponedUpdateConnection;
     const QString m_snippetsGroup;
diff --git a/src/plugins/texteditor/codeassist/codeassistant.cpp b/src/plugins/texteditor/codeassist/codeassistant.cpp
index 8f583e4d381..db5553b03f8 100644
--- a/src/plugins/texteditor/codeassist/codeassistant.cpp
+++ b/src/plugins/texteditor/codeassist/codeassistant.cpp
@@ -77,12 +77,10 @@ private:
 private:
     CodeAssistant *q = nullptr;
     TextEditorWidget *m_editorWidget = nullptr;
-    QMetaObject::Connection m_runnerConnection;
     IAssistProvider *m_requestProvider = nullptr;
     IAssistProcessor *m_processor = nullptr;
     AssistKind m_assistKind = TextEditor::Completion;
     IAssistProposalWidget *m_proposalWidget = nullptr;
-    QScopedPointer<IAssistProposal> m_proposal;
     bool m_receivedContentWhileWaiting = false;
     QTimer m_automaticProposalTimer;
     CompletionSettings m_settings;
@@ -117,12 +115,11 @@ void CodeAssistantPrivate::invoke(AssistKind kind, IAssistProvider *provider)
 {
     stopAutomaticProposalTimer();
 
-    if (isDisplayingProposal() && m_assistKind == kind && !m_proposal->isFragile()
-        && m_proposal->supportsPrefixFiltering(proposalPrefix())) {
+    if (isDisplayingProposal() && m_assistKind == kind && !m_proposalWidget->isFragile()) {
         m_proposalWidget->setReason(ExplicitlyInvoked);
-        m_proposalWidget->updateProposal(m_editorWidget->textAt(
-                        m_proposal->basePosition(),
-                        m_editorWidget->position() - m_proposal->basePosition()));
+        m_proposalWidget->filterProposal(m_editorWidget->textAt(
+                        m_proposalWidget->basePosition(),
+                        m_editorWidget->position() - m_proposalWidget->basePosition()));
     } else {
         requestProposal(ExplicitlyInvoked, kind, provider);
     }
@@ -239,14 +236,12 @@ void CodeAssistantPrivate::displayProposal(IAssistProposal *newProposal, AssistR
         return;
 
     // TODO: The proposal should own the model until someone takes it explicitly away.
-    QScopedPointer<IAssistProposal> proposalCandidate(newProposal);
+    QScopedPointer<IAssistProposal> deleter(newProposal);
 
-    if (isDisplayingProposal() && !m_proposal->isFragile()
-        && !m_proposalWidget->supportsModelUpdate(proposalCandidate->id())) {
+    if (isDisplayingProposal() && !m_proposalWidget->isFragile())
         return;
-    }
 
-    int basePosition = proposalCandidate->basePosition();
+    int basePosition = newProposal->basePosition();
     if (m_editorWidget->position() < basePosition) {
         destroyContext();
         return;
@@ -266,28 +261,16 @@ void CodeAssistantPrivate::displayProposal(IAssistProposal *newProposal, AssistR
         return;
     }
 
-    if (m_proposalWidget
-        && basePosition == proposalCandidate->basePosition()
-        && m_proposalWidget->supportsModelUpdate(proposalCandidate->id())) {
-        m_proposal.reset(proposalCandidate.take());
-        m_proposal->setReason(reason);
-        m_proposalWidget->updateModel(m_proposal->model());
-        m_proposalWidget->updateProposal(prefix);
-        return;
-    }
-
     destroyContext();
 
     clearAbortedPosition();
-    m_proposal.reset(proposalCandidate.take());
-    m_proposal->setReason(reason);
 
-    if (m_proposal->isCorrective(m_editorWidget))
-        m_proposal->makeCorrection(m_editorWidget);
+    if (newProposal->isCorrective(m_editorWidget))
+        newProposal->makeCorrection(m_editorWidget);
 
     m_editorWidget->keepAutoCompletionHighlight(true);
-    basePosition = m_proposal->basePosition();
-    m_proposalWidget = m_proposal->createWidget();
+    basePosition = newProposal->basePosition();
+    m_proposalWidget = newProposal->createWidget();
     connect(m_proposalWidget, &QObject::destroyed,
             this, &CodeAssistantPrivate::finalizeProposal);
     connect(m_proposalWidget, &IAssistProposalWidget::prefixExpanded,
@@ -301,7 +284,7 @@ void CodeAssistantPrivate::displayProposal(IAssistProposal *newProposal, AssistR
     m_proposalWidget->setKind(m_assistKind);
     m_proposalWidget->setBasePosition(basePosition);
     m_proposalWidget->setUnderlyingWidget(m_editorWidget);
-    m_proposalWidget->setModel(m_proposal->model());
+    m_proposalWidget->setModel(newProposal->model());
     m_proposalWidget->setDisplayRect(m_editorWidget->cursorRect(basePosition));
     m_proposalWidget->setIsSynchronized(!m_receivedContentWhileWaiting);
     m_proposalWidget->showProposal(prefix);
@@ -309,9 +292,9 @@ void CodeAssistantPrivate::displayProposal(IAssistProposal *newProposal, AssistR
 
 void CodeAssistantPrivate::processProposalItem(AssistProposalItemInterface *proposalItem)
 {
-    QTC_ASSERT(m_proposal, return);
+    QTC_ASSERT(m_proposalWidget, return);
     TextDocumentManipulator manipulator(m_editorWidget);
-    proposalItem->apply(manipulator, m_proposal->basePosition());
+    proposalItem->apply(manipulator, m_proposalWidget->basePosition());
     destroyContext();
     m_editorWidget->encourageApply();
     if (!proposalItem->isSnippet())
@@ -320,34 +303,33 @@ void CodeAssistantPrivate::processProposalItem(AssistProposalItemInterface *prop
 
 void CodeAssistantPrivate::handlePrefixExpansion(const QString &newPrefix)
 {
-    QTC_ASSERT(m_proposal, return);
+    QTC_ASSERT(m_proposalWidget, return);
 
     QTextCursor cursor(m_editorWidget->document());
-    cursor.setPosition(m_proposal->basePosition());
+    cursor.setPosition(m_proposalWidget->basePosition());
     cursor.movePosition(QTextCursor::EndOfWord);
 
     int currentPosition = m_editorWidget->position();
     const QString textAfterCursor = m_editorWidget->textAt(currentPosition,
                                                        cursor.position() - currentPosition);
     if (!textAfterCursor.startsWith(newPrefix)) {
-        if (newPrefix.indexOf(textAfterCursor, currentPosition - m_proposal->basePosition()) >= 0)
+        if (newPrefix.indexOf(textAfterCursor, currentPosition - m_proposalWidget->basePosition()) >= 0)
             currentPosition = cursor.position();
         const QStringView prefixAddition = QStringView(newPrefix).mid(currentPosition
-                                                                      - m_proposal->basePosition());
+                                                                      - m_proposalWidget->basePosition());
         // If remaining string starts with the prefix addition
         if (textAfterCursor.startsWith(prefixAddition))
             currentPosition += prefixAddition.size();
     }
 
-    m_editorWidget->setCursorPosition(m_proposal->basePosition());
-    m_editorWidget->replace(currentPosition - m_proposal->basePosition(), newPrefix);
+    m_editorWidget->setCursorPosition(m_proposalWidget->basePosition());
+    m_editorWidget->replace(currentPosition - m_proposalWidget->basePosition(), newPrefix);
     notifyChange();
 }
 
 void CodeAssistantPrivate::finalizeProposal()
 {
     stopAutomaticProposalTimer();
-    m_proposal.reset();
     m_proposalWidget = nullptr;
     if (m_receivedContentWhileWaiting)
         m_receivedContentWhileWaiting = false;
@@ -367,8 +349,8 @@ QString CodeAssistantPrivate::proposalPrefix() const
 {
     if (!isDisplayingProposal())
         return {};
-    return m_editorWidget->textAt(m_proposal->basePosition(),
-                                  m_editorWidget->position() - m_proposal->basePosition());
+    return m_editorWidget->textAt(m_proposalWidget->basePosition(),
+                                  m_editorWidget->position() - m_proposalWidget->basePosition());
 }
 
 void CodeAssistantPrivate::invalidateCurrentRequestData()
@@ -409,18 +391,14 @@ void CodeAssistantPrivate::notifyChange()
     stopAutomaticProposalTimer();
 
     if (isDisplayingProposal()) {
-        QTC_ASSERT(m_proposal, return);
-        if (m_editorWidget->position() < m_proposal->basePosition()) {
+        QTC_ASSERT(m_proposalWidget, return);
+        if (m_editorWidget->position() < m_proposalWidget->basePosition()) {
             destroyContext();
         } else {
-            const QString prefix = proposalPrefix();
-            if (m_proposal->supportsPrefixFiltering(prefix)) {
-                m_proposalWidget->updateProposal(prefix);
-                if (!isDisplayingProposal())
-                    requestActivationCharProposal();
-            } else {
-                requestProposal(m_proposal->reason(), m_assistKind, m_requestProvider, true);
-            }
+            m_proposalWidget->updateProposal(
+                m_editorWidget->createAssistInterface(m_assistKind, m_proposalWidget->reason()));
+            if (!isDisplayingProposal())
+                requestActivationCharProposal();
         }
     }
 }
@@ -466,7 +444,7 @@ void CodeAssistantPrivate::automaticProposalTimeout()
 {
     if (isWaitingForProposal()
         || m_editorWidget->multiTextCursor().hasMultipleCursors()
-        || (isDisplayingProposal() && !m_proposal->isFragile())) {
+        || (isDisplayingProposal() && !m_proposalWidget->isFragile())) {
         return;
     }
 
@@ -488,8 +466,8 @@ void CodeAssistantPrivate::updateFromCompletionSettings(
 
 void CodeAssistantPrivate::explicitlyAborted()
 {
-    QTC_ASSERT(m_proposal, return);
-    m_abortedBasePosition = m_proposal->basePosition();
+    QTC_ASSERT(m_proposalWidget, return);
+    m_abortedBasePosition = m_proposalWidget->basePosition();
 }
 
 void CodeAssistantPrivate::clearAbortedPosition()
diff --git a/src/plugins/texteditor/codeassist/functionhintproposal.cpp b/src/plugins/texteditor/codeassist/functionhintproposal.cpp
index 5c713d23303..fcc3b247eb7 100644
--- a/src/plugins/texteditor/codeassist/functionhintproposal.cpp
+++ b/src/plugins/texteditor/codeassist/functionhintproposal.cpp
@@ -12,9 +12,7 @@ using namespace TextEditor;
 FunctionHintProposal::FunctionHintProposal(int cursorPos, FunctionHintProposalModelPtr model)
     : IAssistProposal(functionHintId, cursorPos)
     , m_model(model)
-{
-    setFragile(true);
-}
+{}
 
 FunctionHintProposal::~FunctionHintProposal() = default;
 
diff --git a/src/plugins/texteditor/codeassist/functionhintproposalwidget.cpp b/src/plugins/texteditor/codeassist/functionhintproposalwidget.cpp
index 5811c100c8b..e6753c46051 100644
--- a/src/plugins/texteditor/codeassist/functionhintproposalwidget.cpp
+++ b/src/plugins/texteditor/codeassist/functionhintproposalwidget.cpp
@@ -138,6 +138,7 @@ FunctionHintProposalWidget::FunctionHintProposalWidget()
     });
 
     setFocusPolicy(Qt::NoFocus);
+    setFragile(true);
 }
 
 FunctionHintProposalWidget::~FunctionHintProposalWidget()
@@ -150,9 +151,6 @@ void FunctionHintProposalWidget::setAssistant(CodeAssistant *assistant)
     d->m_assistant = assistant;
 }
 
-void FunctionHintProposalWidget::setReason(AssistReason)
-{}
-
 void FunctionHintProposalWidget::setKind(AssistKind)
 {}
 
@@ -190,7 +188,7 @@ void FunctionHintProposalWidget::showProposal(const QString &prefix)
     d->m_popupFrame->show();
 }
 
-void FunctionHintProposalWidget::updateProposal(const QString &prefix)
+void FunctionHintProposalWidget::filterProposal(const QString &prefix)
 {
     updateAndCheck(prefix);
 }
diff --git a/src/plugins/texteditor/codeassist/functionhintproposalwidget.h b/src/plugins/texteditor/codeassist/functionhintproposalwidget.h
index 28813ccf8cb..97580ede248 100644
--- a/src/plugins/texteditor/codeassist/functionhintproposalwidget.h
+++ b/src/plugins/texteditor/codeassist/functionhintproposalwidget.h
@@ -19,7 +19,6 @@ public:
     ~FunctionHintProposalWidget() override;
 
     void setAssistant(CodeAssistant *assistant) override;
-    void setReason(AssistReason reason) override;
     void setKind(AssistKind kind) override;
     void setUnderlyingWidget(const QWidget *underlyingWidget) override;
     void setModel(ProposalModelPtr model) override;
@@ -27,7 +26,7 @@ public:
     void setIsSynchronized(bool isSync) override;
 
     void showProposal(const QString &prefix) override;
-    void updateProposal(const QString &prefix) override;
+    void filterProposal(const QString &prefix) override;
     void closeProposal() override;
 
     bool proposalIsVisible() const override;
diff --git a/src/plugins/texteditor/codeassist/genericproposalwidget.cpp b/src/plugins/texteditor/codeassist/genericproposalwidget.cpp
index 83fe23404ff..9eb3fdcd373 100644
--- a/src/plugins/texteditor/codeassist/genericproposalwidget.cpp
+++ b/src/plugins/texteditor/codeassist/genericproposalwidget.cpp
@@ -249,7 +249,6 @@ public:
     QRect m_displayRect;
     bool m_isSynchronized = true;
     bool m_explicitlySelected = false;
-    AssistReason m_reason = IdleEditor;
     AssistKind m_kind = Completion;
     bool m_justInvoked = false;
     QPointer<GenericProposalInfoFrame> m_infoFrame;
@@ -358,9 +357,9 @@ void GenericProposalWidget::setAssistant(CodeAssistant *assistant)
 
 void GenericProposalWidget::setReason(AssistReason reason)
 {
-    d->m_reason = reason;
-    if (d->m_reason == ExplicitlyInvoked)
+    if (reason == ExplicitlyInvoked)
         d->m_justInvoked = true;
+    IAssistProposalWidget::setReason(reason);
 }
 
 void GenericProposalWidget::setKind(AssistKind kind)
@@ -393,11 +392,6 @@ void GenericProposalWidget::setIsSynchronized(bool isSync)
     d->m_isSynchronized = isSync;
 }
 
-bool GenericProposalWidget::supportsModelUpdate(const Utils::Id &proposalId) const
-{
-    return proposalId == Constants::GENERIC_PROPOSAL_ID;
-}
-
 void GenericProposalWidget::updateModel(ProposalModelPtr model)
 {
     QString currentText;
@@ -418,6 +412,7 @@ void GenericProposalWidget::updateModel(ProposalModelPtr model)
         d->m_completionListView->selectRow(currentRow);
     else
         d->m_explicitlySelected = false;
+    updatePositionAndSize();
 }
 
 void GenericProposalWidget::showProposal(const QString &prefix)
@@ -431,7 +426,7 @@ void GenericProposalWidget::showProposal(const QString &prefix)
     d->m_completionListView->setFocus();
 }
 
-void GenericProposalWidget::updateProposal(const QString &prefix)
+void GenericProposalWidget::filterProposal(const QString &prefix)
 {
     if (!isVisible())
         return;
@@ -470,7 +465,7 @@ bool GenericProposalWidget::updateAndCheck(const QString &prefix)
         if (!prefix.isEmpty())
             d->m_model->filter(prefix);
     }
-    if (!d->m_model->hasItemsToPropose(prefix, d->m_reason)) {
+    if (!d->m_model->hasItemsToPropose(prefix, reason())) {
         d->m_completionListView->reset();
         abort();
         return false;
@@ -660,7 +655,7 @@ bool GenericProposalWidget::eventFilter(QObject *o, QEvent *e)
             AssistProposalItemInterface *item =
                 d->m_model->proposalItem(d->m_completionListView->currentIndex().row());
             if (item->prematurelyApplies(typedChar)
-                    && (d->m_reason == ExplicitlyInvoked || item->text().endsWith(typedChar))) {
+                    && (reason() == ExplicitlyInvoked || item->text().endsWith(typedChar))) {
                 abort();
                 emit proposalItemActivated(item);
                 return true;
diff --git a/src/plugins/texteditor/codeassist/genericproposalwidget.h b/src/plugins/texteditor/codeassist/genericproposalwidget.h
index 901a8b1dfea..c38ccc9f47f 100644
--- a/src/plugins/texteditor/codeassist/genericproposalwidget.h
+++ b/src/plugins/texteditor/codeassist/genericproposalwidget.h
@@ -31,11 +31,10 @@ public:
     void setDisplayRect(const QRect &rect) override;
     void setIsSynchronized(bool isSync) override;
 
-    bool supportsModelUpdate(const Utils::Id &proposalId) const override;
-    void updateModel(ProposalModelPtr model) override;
+    void updateModel(ProposalModelPtr model);
 
     void showProposal(const QString &prefix) override;
-    void updateProposal(const QString &prefix) override;
+    void filterProposal(const QString &prefix) override;
     void closeProposal() override;
 
 private:
diff --git a/src/plugins/texteditor/codeassist/iassistproposal.cpp b/src/plugins/texteditor/codeassist/iassistproposal.cpp
index b2c7dffc9f3..d6918ba7972 100644
--- a/src/plugins/texteditor/codeassist/iassistproposal.cpp
+++ b/src/plugins/texteditor/codeassist/iassistproposal.cpp
@@ -63,16 +63,6 @@ int IAssistProposal::basePosition() const
     return m_basePosition;
 }
 
-bool IAssistProposal::isFragile() const
-{
-    return m_isFragile;
-}
-
-bool IAssistProposal::supportsPrefixFiltering(const QString &prefix) const
-{
-    return !m_prefixChecker || m_prefixChecker(prefix);
-}
-
 /*!
     \fn bool TextEditor::IAssistProposal::isCorrective() const
 
@@ -98,16 +88,6 @@ void IAssistProposal::makeCorrection(TextEditorWidget *editorWidget)
     Q_UNUSED(editorWidget)
 }
 
-void IAssistProposal::setFragile(bool fragile)
-{
-    m_isFragile = fragile;
-}
-
-void IAssistProposal::setPrefixChecker(const PrefixChecker checker)
-{
-    m_prefixChecker = checker;
-}
-
 /*!
     \fn IAssistModel *TextEditor::IAssistProposal::model() const
 
diff --git a/src/plugins/texteditor/codeassist/iassistproposal.h b/src/plugins/texteditor/codeassist/iassistproposal.h
index 5c64a880665..1761fc29bf8 100644
--- a/src/plugins/texteditor/codeassist/iassistproposal.h
+++ b/src/plugins/texteditor/codeassist/iassistproposal.h
@@ -22,30 +22,17 @@ public:
     virtual ~IAssistProposal();
 
     int basePosition() const;
-    bool isFragile() const;
-    bool supportsPrefixFiltering(const QString &prefix) const;
     virtual bool hasItemsToPropose(const QString &, AssistReason) const { return true; }
     virtual bool isCorrective(TextEditorWidget *editorWidget) const;
     virtual void makeCorrection(TextEditorWidget *editorWidget);
     virtual TextEditor::ProposalModelPtr model() const = 0;
     virtual IAssistProposalWidget *createWidget() const = 0;
 
-    void setFragile(bool fragile);
-
     Utils::Id id() const { return m_id; }
 
-    AssistReason reason() const { return m_reason; }
-    void setReason(const AssistReason &reason) { m_reason = reason; }
-
-    using PrefixChecker = std::function<bool(const QString &)>;
-    void setPrefixChecker(const PrefixChecker checker);
-
 protected:
     Utils::Id m_id;
     int m_basePosition;
-    bool m_isFragile = false;
-    PrefixChecker m_prefixChecker;
-    AssistReason m_reason = IdleEditor;
 };
 
 } // TextEditor
diff --git a/src/plugins/texteditor/codeassist/iassistproposalwidget.cpp b/src/plugins/texteditor/codeassist/iassistproposalwidget.cpp
index f1ea7428ebc..fe5e3d823da 100644
--- a/src/plugins/texteditor/codeassist/iassistproposalwidget.cpp
+++ b/src/plugins/texteditor/codeassist/iassistproposalwidget.cpp
@@ -3,6 +3,8 @@
 
 #include "iassistproposalwidget.h"
 
+#include "assistinterface.h"
+
 using namespace TextEditor;
 
 /*!
@@ -30,6 +32,11 @@ IAssistProposalWidget::IAssistProposalWidget()
     : QFrame(nullptr, Qt::Popup)
 {}
 
+void IAssistProposalWidget::updateProposal(std::unique_ptr<AssistInterface> &&interface)
+{
+    filterProposal(interface->textAt(m_basePosition, interface->position() - m_basePosition));
+}
+
 IAssistProposalWidget::~IAssistProposalWidget() = default;
 
 int IAssistProposalWidget::basePosition() const
diff --git a/src/plugins/texteditor/codeassist/iassistproposalwidget.h b/src/plugins/texteditor/codeassist/iassistproposalwidget.h
index fafe1b48b4a..68600b399c9 100644
--- a/src/plugins/texteditor/codeassist/iassistproposalwidget.h
+++ b/src/plugins/texteditor/codeassist/iassistproposalwidget.h
@@ -14,8 +14,9 @@ namespace Utils { class Id; }
 
 namespace TextEditor {
 
-class CodeAssistant;
+class AssistInterface;
 class AssistProposalItemInterface;
+class CodeAssistant;
 
 class TEXTEDITOR_EXPORT IAssistProposalWidget  : public QFrame
 {
@@ -26,7 +27,7 @@ public:
     ~IAssistProposalWidget() override;
 
     virtual void setAssistant(CodeAssistant *assistant) = 0;
-    virtual void setReason(AssistReason reason) = 0;
+    virtual void setReason(AssistReason reason) { m_reason = reason; }
     virtual void setKind(AssistKind kind) = 0;
     virtual void setUnderlyingWidget(const QWidget *underlyingWidget) = 0;
     virtual void setModel(ProposalModelPtr model) = 0;
@@ -34,16 +35,20 @@ public:
     virtual void setIsSynchronized(bool isSync) = 0;
 
     virtual void showProposal(const QString &prefix) = 0;
-    virtual void updateProposal(const QString &prefix) = 0;
+    virtual void filterProposal(const QString &prefix) = 0;
+    virtual void updateProposal(std::unique_ptr<AssistInterface> &&interface);
     virtual void closeProposal() = 0;
 
     virtual bool proposalIsVisible() const { return isVisible(); }
-    virtual bool supportsModelUpdate(const Utils::Id &/*proposalId*/) const { return false; }
-    virtual void updateModel(ProposalModelPtr) {}
 
     int basePosition() const;
     void setBasePosition(int basePosition);
 
+    void setFragile(bool fragile) { m_isFragile = fragile; }
+    bool isFragile() const { return m_isFragile; }
+
+    AssistReason reason() const { return m_reason; }
+
 signals:
     void prefixExpanded(const QString &newPrefix);
     void proposalItemActivated(AssistProposalItemInterface *proposalItem);
@@ -51,6 +56,8 @@ signals:
 
 protected:
     int m_basePosition = -1;
+    bool m_isFragile = false;
+    AssistReason m_reason = IdleEditor;
 };
 
 } // TextEditor