Step 146: add Emacs buffer bridge

editor/src/EditorState.h

@@ -188,6 +188,7 @@ struct EditorState {
     EmacsFunctionIndex emacsFunctionIndex;
     bool              emacsFunctionIndexDirty = true;
     EmacsKeybindingState emacsKeys;
+    bool              showEmacsBridgePanel = false;
     bool              showOrgPanel = true;
     OrgDocumentState  orgDoc;
     int               orgTempCounter = 0;
@@ -1434,6 +1435,48 @@ struct EditorState {
         updateEmacsModeLine(emacsKeys, emacs, nowSeconds, outputLog);
     }
 
+    void pullFromEmacs() {
+        if (!active()) return;
+        if (active()->path.rfind("(untitled", 0) == 0) {
+            outputLog += "[emacs] Save file before syncing.\n";
+            return;
+        }
+        std::string text = emacs.getBufferText(active()->path);
+        if (!emacs.getLastError().empty() && text == "error") {
+            outputLog += "[emacs] " + emacs.getLastError() + "\n";
+            return;
+        }
+        active()->editBuf = text;
+        onTextChanged();
+        outputLog += "[emacs] Pulled buffer from Emacs.\n";
+    }
+
+    void pushToEmacs() {
+        if (!active()) return;
+        if (active()->path.rfind("(untitled", 0) == 0) {
+            outputLog += "[emacs] Save file before syncing.\n";
+            return;
+        }
+        if (!emacs.setBufferText(active()->path, active()->editBuf)) {
+            outputLog += "[emacs] " + emacs.getLastError() + "\n";
+            return;
+        }
+        outputLog += "[emacs] Pushed buffer to Emacs.\n";
+    }
+
+    void openInEmacsFrame() {
+        if (!active()) return;
+        if (active()->path.rfind("(untitled", 0) == 0) {
+            outputLog += "[emacs] Save file before opening in Emacs.\n";
+            return;
+        }
+        if (!emacs.openFileInEmacsFrame(active()->path)) {
+            outputLog += "[emacs] " + emacs.getLastError() + "\n";
+            return;
+        }
+        outputLog += "[emacs] Opened in Emacs frame.\n";
+    }
+
     std::string buildRunCommand(const std::string& path,
                                 const std::string& language,
                                 bool buildOnly) const {

editor/src/EmacsIntegration.h

@@ -106,6 +106,20 @@ public:
     static std::string modeLine() {
         return "(format-mode-line mode-line-format)";
     }
+
+    // Build an Elisp expression to read a buffer for a given file
+    static std::string bufferStringForFile(const std::string& path) {
+        return "(with-current-buffer (find-file-noselect \"" +
+               escapeString(path) + "\") (buffer-string))";
+    }
+
+    // Build an Elisp expression to replace a buffer's contents and save
+    static std::string replaceBufferForFile(const std::string& path, const std::string& text) {
+        return "(with-current-buffer (find-file-noselect \"" + escapeString(path) + "\") "
+               "(erase-buffer) "
+               "(insert \"" + escapeString(text) + "\") "
+               "(save-buffer))";
+    }
 };
 
 // ---------------------------------------------------------------------------
@@ -213,6 +227,27 @@ public:
         return output;
     }
 
+    std::string getBufferText(const std::string& path) {
+        return sendCommand(ElispCommandBuilder::bufferStringForFile(path));
+    }
+
+    bool setBufferText(const std::string& path, const std::string& text) {
+        std::string result = sendCommand(ElispCommandBuilder::replaceBufferForFile(path, text));
+        if (!lastError_.empty() && result == "error") return false;
+        return true;
+    }
+
+    bool openFileInEmacsFrame(const std::string& path) {
+        lastError_.clear();
+        std::string cmd = emacsclientPath_ + " -c -n \"" + path + "\"";
+        int code = runCommand(cmd);
+        if (code != 0) {
+            lastError_ = "emacsclient failed to open frame";
+            return false;
+        }
+        return true;
+    }
+
     // Auto-restart daemon if it died
     bool ensureDaemon() {
         if (daemonRunning_ && isDaemonAlive()) return true;
@@ -300,6 +335,12 @@ public:
         lastSentCommand_ = elispCommand;
 
         // Simulate responses for known commands
+        if (elispCommand.find("buffer-string") != std::string::npos) {
+            return "mock-buffer";
+        }
+        if (elispCommand.find("erase-buffer") != std::string::npos) {
+            return "t";
+        }
         if (elispCommand.find("find-file") != std::string::npos) {
             return "t";  // success
         }
@@ -356,7 +397,6 @@ public:
         if (elispCommand.find("format-mode-line") != std::string::npos) {
             return "Emacs: Fundamental (Whetstone)";
         }
-
         // Unknown command — simulate error
         lastError_ = "void-function";
         return "error";
@@ -372,10 +412,18 @@ public:
     // Test helper: get the last command sent
     std::string getLastSentCommand() const { return lastSentCommand_; }
     std::string getLastInitPath() const { return lastInitPath_; }
+    std::string getLastRunCommand() const { return lastRunCommand_; }
+
+protected:
+    int runCommand(const std::string& cmd) const override {
+        lastRunCommand_ = cmd;
+        return 0;
+    }
 
 private:
     std::string lastError_;
     std::string lastSentCommand_;
     std::string lastInitPath_;
+    mutable std::string lastRunCommand_;
 };
 

editor/src/main.cpp

@@ -360,6 +360,7 @@ int main(int, char**) {
                 ImGui::MenuItem("Libraries", nullptr, &state.showLibraryBrowserPanel);
                 ImGui::MenuItem("Compose", nullptr, &state.showCompositionPanel);
                 ImGui::MenuItem("Emacs Packages", nullptr, &state.showEmacsPackagesPanel);
+                ImGui::MenuItem("Emacs Bridge", nullptr, &state.showEmacsBridgePanel);
                 ImGui::MenuItem("Settings", nullptr, &state.showSettingsPanel);
                 ImGui::MenuItem("LSP Servers...", nullptr, &state.showLspSettings);
                 if (state.active()) {
@@ -674,6 +675,30 @@ int main(int, char**) {
             ImGui::End();
         }
 
+        if (state.showEmacsBridgePanel) {
+            ImGui::Begin("Emacs Bridge", &state.showEmacsBridgePanel);
+            ImGui::PushFont(uiFont);
+            if (state.active()) {
+                ImGui::Text("Active file: %s", state.active()->path.c_str());
+            } else {
+                ImGui::TextDisabled("(no active buffer)");
+            }
+            ImGui::Separator();
+            if (ImGui::Button("Open Emacs Frame")) {
+                state.openInEmacsFrame();
+            }
+            ImGui::SameLine();
+            if (ImGui::Button("Pull From Emacs")) {
+                state.pullFromEmacs();
+            }
+            ImGui::SameLine();
+            if (ImGui::Button("Push To Emacs")) {
+                state.pushToEmacs();
+            }
+            ImGui::PopFont();
+            ImGui::End();
+        }
+
         if (state.layoutPreset == LayoutPreset::Emacs && state.emacsKeys.minibufferActive) {
             ImGuiWindowFlags mbFlags = ImGuiWindowFlags_NoDecoration |
                 ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoSavedSettings |