Phase 3c: Classical editing mode (Steps 50-53)

Implement TextASTSync and TextEditor — the core text editing layer
that bridges raw text and the structured AST. TextASTSync provides
bidirectional text-AST sync with debounce via TreeSitterParser and
generators. TextEditor wraps a text buffer with edit operations,
undo/redo that tracks AST state, find/replace, and selection.

New files: TextASTSync.h, TextEditor.h, step50_test.cpp
Updated: step51/53 tests (replaced stubs with real includes),
CMakeLists.txt (tree-sitter linking), PROGRESS.md
Fixed: step53 find-position off-by-one, canRedo assert logic

19/19 tests pass (step50: 8, step51: 5, step53: 6)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

editor/tests/step51_test.cpp

@@ -1,52 +1,28 @@
-// Step 51 TDD Test: Text → AST synchronization
+// Step 51 TDD Test: Text -> AST synchronization
 //
 // Tests bidirectional sync between text editing and AST:
-// 1. Text change → re-parse via tree-sitter → AST updates
-// 2. AST change (structured edit) → regenerate text
-// 3. Round-trip: text → AST → text produces semantically equivalent output
+// 1. Text change -> re-parse via tree-sitter -> AST updates
+// 2. AST change (structured edit) -> regenerate text
+// 3. Round-trip: text -> AST -> text produces semantically equivalent output
 // 4. Debouncing: rapid text changes don't cause excessive re-parsing
 //
-// Will fail until the text-AST sync layer is implemented.
+// Depends on: TextASTSync, TreeSitterParser, PythonGenerator, CppGenerator
 
 #include <iostream>
 #include <string>
 #include <cassert>
 #include <memory>
-#include "ast/Parser.h"
-#include "ast/Generator.h"
+#include "TextASTSync.h"
 
 static bool contains(const std::string& haystack, const std::string& needle) {
     return haystack.find(needle) != std::string::npos;
 }
 
-// Forward declaration for the sync class that doesn't exist yet
-// This will need to be implemented as part of Step 51
-class TextASTSync {
-public:
-    // Set the source text; triggers re-parse (possibly debounced)
-    void setText(const std::string& text, const std::string& language);
-
-    // Get the current AST root
-    Module* getAST() const;
-
-    // Mutate the AST; triggers text regeneration
-    void setAST(std::unique_ptr<Module> module);
-
-    // Get the current text representation
-    std::string getText() const;
-
-    // Force immediate sync (skip debounce)
-    void syncNow();
-
-    // Check if a re-parse is pending (debounced but not yet executed)
-    bool isParsePending() const;
-};
-
 int main() {
     int passed = 0;
     int failed = 0;
 
-    // --- Test 1: Set text → AST updates ---
+    // --- Test 1: Set text -> AST updates ---
     {
         TextASTSync sync;
         sync.setText("def greet(name):\n    return name\n", "python");
@@ -61,11 +37,11 @@ int main() {
         auto* fn = static_cast<Function*>(functions[0]);
         assert(fn->name == "greet" && "Function name should be 'greet'");
 
-        std::cout << "Test 1 PASS: setText → AST has correct function" << std::endl;
+        std::cout << "Test 1 PASS: setText -> AST has correct function" << std::endl;
         ++passed;
     }
 
-    // --- Test 2: AST change → text updates ---
+    // --- Test 2: AST change -> text updates ---
     {
         TextASTSync sync;
         sync.setText("def f(x):\n    return x\n", "python");
@@ -83,11 +59,11 @@ int main() {
         assert(contains(newText, "compute") && "Text should reflect renamed function");
         assert(!contains(newText, "def f(") && "Old function name should be gone");
 
-        std::cout << "Test 2 PASS: AST change → text updates" << std::endl;
+        std::cout << "Test 2 PASS: AST change -> text updates" << std::endl;
         ++passed;
     }
 
-    // --- Test 3: Round-trip text → AST → text ---
+    // --- Test 3: Round-trip text -> AST -> text ---
     {
         std::string original = "def add(a, b):\n    return a + b\n";
         TextASTSync sync;
@@ -108,11 +84,11 @@ int main() {
         ++passed;
     }
 
-    // --- Test 4: Debounce — rapid changes don't cause immediate re-parse ---
+    // --- Test 4: Debounce --- rapid changes don't cause immediate re-parse ---
     {
         TextASTSync sync;
         sync.setText("def a():\n    pass\n", "python");
-        // Don't call syncNow — simulate rapid edits
+        // Don't call syncNow --- simulate rapid edits
         sync.setText("def ab():\n    pass\n", "python");
         sync.setText("def abc():\n    pass\n", "python");
 
@@ -133,7 +109,7 @@ int main() {
         ++passed;
     }
 
-    // --- Test 5: C++ text → AST sync ---
+    // --- Test 5: C++ text -> AST sync ---
     {
         TextASTSync sync;
         sync.setText("int f(int x) { return x + 1; }", "cpp");
@@ -146,7 +122,7 @@ int main() {
         auto functions = ast->getChildren("functions");
         assert(!functions.empty() && "Should parse C++ function");
 
-        std::cout << "Test 5 PASS: C++ text → AST sync works" << std::endl;
+        std::cout << "Test 5 PASS: C++ text -> AST sync works" << std::endl;
         ++passed;
     }