Step 559: add call stack frame inspector model

editor/src/CallStackFrameInspector.h

@@ -0,0 +1,58 @@
+#pragma once
+// Step 559: Call Stack and Frame Inspector
+
+#include <map>
+#include <string>
+#include <vector>
+
+struct FrameScope {
+    int frameIndex = 0;
+    std::string functionName;
+    std::string filePath;
+    int line = 0;
+    std::map<std::string, std::string> variables;
+};
+
+struct FrameInspectorResult {
+    bool ok = false;
+    int selectedIndex = -1;
+    FrameScope selected;
+    std::vector<std::string> errors;
+};
+
+class CallStackFrameInspector {
+public:
+    static FrameInspectorResult inspect(const std::vector<FrameScope>& frames,
+                                        int requestedIndex) {
+        FrameInspectorResult out;
+        if (frames.empty()) {
+            out.errors.push_back("empty_stack");
+            return out;
+        }
+        if (requestedIndex < 0 || requestedIndex >= (int)frames.size()) {
+            out.errors.push_back("invalid_frame_index");
+            return out;
+        }
+        if (!isFrameValid(frames[requestedIndex])) {
+            out.errors.push_back("invalid_frame_payload");
+            return out;
+        }
+
+        out.ok = true;
+        out.selectedIndex = requestedIndex;
+        out.selected = frames[requestedIndex];
+        return out;
+    }
+
+    static std::vector<std::string> variableNames(const FrameScope& frame) {
+        std::vector<std::string> names;
+        for (const auto& kv : frame.variables) names.push_back(kv.first);
+        return names;
+    }
+
+private:
+    static bool isFrameValid(const FrameScope& f) {
+        return f.frameIndex >= 0 && !f.functionName.empty() &&
+               !f.filePath.empty() && f.line > 0;
+    }
+};