diff --git a/editor/CMakeLists.txt b/editor/CMakeLists.txt
index 6576aeb..2c9e4fa 100644
--- a/editor/CMakeLists.txt
+++ b/editor/CMakeLists.txt
@@ -202,6 +202,9 @@ target_include_directories(step69_test PRIVATE src)
 add_executable(step70_test tests/step70_test.cpp)
 target_include_directories(step70_test PRIVATE src)
 
+add_executable(step71_test tests/step71_test.cpp)
+target_include_directories(step71_test PRIVATE src)
+
 add_executable(whetstone_editor src/main.cpp)
 target_include_directories(whetstone_editor PRIVATE src)
 # find_package(SDL2 REQUIRED)  # Commented out for now to avoid build issues
diff --git a/editor/tests/step71_test.cpp b/editor/tests/step71_test.cpp
new file mode 100644
index 0000000..e1a25b6
--- /dev/null
+++ b/editor/tests/step71_test.cpp
@@ -0,0 +1,267 @@
+// Step 71 TDD Test: Incremental optimization with rollback
+//
+// Tests incremental transform tracking and selective undo:
+// 1. Apply 3 transforms → all recorded in journal with provenance
+// 2. Undo middle transform → AST reflects only transforms 1 and 3
+// 3. Undo all transforms → AST back to original state
+// 4. Each node knows which transform created/modified it
+// 5. Undo individual transform by ID
+//
+// Will fail until incremental optimization with rollback is implemented.
+
+#include <iostream>
+#include <string>
+#include <cassert>
+#include <vector>
+#include "ast/ASTNode.h"
+#include "ast/Module.h"
+#include "ast/Function.h"
+#include "ast/Variable.h"
+#include "ast/Statement.h"
+#include "ast/Expression.h"
+
+// Forward declaration — IncrementalOptimizer
+class IncrementalOptimizer {
+public:
+    struct TransformRecord {
+        std::string transformId;
+        std::string transformName;  // e.g., "constant-fold", "dead-code-elim"
+        std::vector<std::string> affectedNodeIds;
+    };
+
+    void setRoot(ASTNode* root);
+
+    // Apply a named transform, returns its ID
+    std::string applyTransform(const std::string& transformName);
+
+    // Get all applied transforms in order
+    std::vector<TransformRecord> getTransformHistory() const;
+
+    // Undo a specific transform by ID
+    bool undoTransform(const std::string& transformId);
+
+    // Undo the most recent transform
+    bool undoLast();
+
+    // Get which transform created/modified a given node
+    std::string getProvenance(const std::string& nodeId) const;
+};
+
+int main() {
+    int passed = 0;
+    int failed = 0;
+
+    // --- Test 1: Apply transforms and record in journal ---
+    {
+        Module mod("m1", "Test", "python");
+        Function* fn = new Function("f1", "calc");
+
+        // return (3 + 4) + (5 + 6)
+        Return* ret = new Return();
+        ret->id = "r1";
+
+        BinaryOperation* outerAdd = new BinaryOperation("outer", "+");
+
+        BinaryOperation* leftAdd = new BinaryOperation("left", "+");
+        IntegerLiteral* l1 = new IntegerLiteral("i1", 3);
+        IntegerLiteral* l2 = new IntegerLiteral("i2", 4);
+        leftAdd->setChild("left", l1);
+        leftAdd->setChild("right", l2);
+
+        BinaryOperation* rightAdd = new BinaryOperation("right", "+");
+        IntegerLiteral* l3 = new IntegerLiteral("i3", 5);
+        IntegerLiteral* l4 = new IntegerLiteral("i4", 6);
+        rightAdd->setChild("left", l3);
+        rightAdd->setChild("right", l4);
+
+        outerAdd->setChild("left", leftAdd);
+        outerAdd->setChild("right", rightAdd);
+        ret->setChild("value", outerAdd);
+        fn->addChild("body", ret);
+        mod.addChild("functions", fn);
+
+        IncrementalOptimizer opt;
+        opt.setRoot(&mod);
+
+        // Apply constant folding multiple times
+        std::string t1 = opt.applyTransform("constant-fold");
+        assert(!t1.empty() && "Should return a transform ID");
+
+        auto history = opt.getTransformHistory();
+        assert(!history.empty() && "Should have at least one transform in history");
+
+        std::cout << "Test 1 PASS: Transform recorded in history" << std::endl;
+        ++passed;
+
+        delete l4;
+        delete l3;
+        delete rightAdd;
+        delete l2;
+        delete l1;
+        delete leftAdd;
+        delete outerAdd;
+        delete ret;
+        delete fn;
+    }
+
+    // --- Test 2: Undo last transform ---
+    {
+        Module mod("m1", "Test", "python");
+        Function* fn = new Function("f1", "simple");
+
+        // return 3 + 4
+        Return* ret = new Return();
+        ret->id = "r1";
+        BinaryOperation* binOp = new BinaryOperation("b1", "+");
+        IntegerLiteral* left = new IntegerLiteral("i1", 3);
+        IntegerLiteral* right = new IntegerLiteral("i2", 4);
+        binOp->setChild("left", left);
+        binOp->setChild("right", right);
+        ret->setChild("value", binOp);
+        fn->addChild("body", ret);
+        mod.addChild("functions", fn);
+
+        IncrementalOptimizer opt;
+        opt.setRoot(&mod);
+
+        // Before transform
+        auto* valueBefore = ret->getChild("value");
+        assert(valueBefore->conceptType == "BinaryOperation" && "Before: BinaryOperation");
+
+        // Apply constant fold
+        std::string tid = opt.applyTransform("constant-fold");
+
+        // After transform: should be IntegerLiteral(7)
+        auto* valueAfter = ret->getChild("value");
+        assert(valueAfter->conceptType == "IntegerLiteral" && "After fold: IntegerLiteral");
+
+        // Undo
+        bool undone = opt.undoLast();
+        assert(undone && "Undo should succeed");
+
+        // After undo: should be back to BinaryOperation
+        auto* valueUndone = ret->getChild("value");
+        assert(valueUndone->conceptType == "BinaryOperation" &&
+               "After undo: should be BinaryOperation again");
+
+        std::cout << "Test 2 PASS: Undo last transform restores original" << std::endl;
+        ++passed;
+
+        delete right;
+        delete left;
+        delete binOp;
+        delete ret;
+        delete fn;
+    }
+
+    // --- Test 3: Undo specific transform by ID ---
+    {
+        Module mod("m1", "Test", "python");
+        Function* fn = new Function("f1", "multi");
+
+        // Build body: x = 1; return 3 + 4; y = 2;
+        Assignment* assign1 = new Assignment();
+        assign1->id = "as1";
+        VariableReference* t1 = new VariableReference("vr1", "x");
+        IntegerLiteral* v1 = new IntegerLiteral("i1", 1);
+        assign1->setChild("target", t1);
+        assign1->setChild("value", v1);
+        fn->addChild("body", assign1);
+
+        Return* ret = new Return();
+        ret->id = "r1";
+        BinaryOperation* binOp = new BinaryOperation("b1", "+");
+        IntegerLiteral* left = new IntegerLiteral("i2", 3);
+        IntegerLiteral* right = new IntegerLiteral("i3", 4);
+        binOp->setChild("left", left);
+        binOp->setChild("right", right);
+        ret->setChild("value", binOp);
+        fn->addChild("body", ret);
+
+        Assignment* assign2 = new Assignment();
+        assign2->id = "as2";
+        VariableReference* t2 = new VariableReference("vr2", "y");
+        IntegerLiteral* v2 = new IntegerLiteral("i4", 2);
+        assign2->setChild("target", t2);
+        assign2->setChild("value", v2);
+        fn->addChild("body", assign2);
+
+        mod.addChild("functions", fn);
+
+        IncrementalOptimizer opt;
+        opt.setRoot(&mod);
+
+        // Apply two transforms
+        std::string foldId = opt.applyTransform("constant-fold");
+        std::string dceId = opt.applyTransform("dead-code-elim");
+
+        // Undo just the fold, keeping DCE
+        bool undone = opt.undoTransform(foldId);
+        assert(undone && "Should be able to undo specific transform");
+
+        // The constant fold should be undone (3+4 back to BinaryOperation)
+        // but dead code elimination should remain
+        auto history = opt.getTransformHistory();
+        bool foldStillThere = false;
+        for (const auto& h : history) {
+            if (h.transformId == foldId) foldStillThere = true;
+        }
+        assert(!foldStillThere && "Undone transform should be removed from history");
+
+        std::cout << "Test 3 PASS: Undo specific transform by ID" << std::endl;
+        ++passed;
+
+        delete v2;
+        delete t2;
+        delete assign2;
+        delete right;
+        delete left;
+        delete binOp;
+        delete ret;
+        delete v1;
+        delete t1;
+        delete assign1;
+        delete fn;
+    }
+
+    // --- Test 4: Provenance tracking ---
+    {
+        Module mod("m1", "Test", "python");
+        Function* fn = new Function("f1", "prov");
+
+        Return* ret = new Return();
+        ret->id = "r1";
+        BinaryOperation* binOp = new BinaryOperation("b1", "+");
+        IntegerLiteral* left = new IntegerLiteral("i1", 10);
+        IntegerLiteral* right = new IntegerLiteral("i2", 20);
+        binOp->setChild("left", left);
+        binOp->setChild("right", right);
+        ret->setChild("value", binOp);
+        fn->addChild("body", ret);
+        mod.addChild("functions", fn);
+
+        IncrementalOptimizer opt;
+        opt.setRoot(&mod);
+
+        std::string tid = opt.applyTransform("constant-fold");
+
+        // The folded literal node should know which transform created it
+        auto* foldedNode = ret->getChild("value");
+        std::string provenance = opt.getProvenance(foldedNode->id);
+        assert(!provenance.empty() && "Folded node should have provenance");
+        assert(provenance == tid && "Provenance should match the transform ID");
+
+        std::cout << "Test 4 PASS: Provenance tracks which transform created node" << std::endl;
+        ++passed;
+
+        delete right;
+        delete left;
+        delete binOp;
+        delete ret;
+        delete fn;
+    }
+
+    // --- Summary ---
+    std::cout << "\n=== Step 71 Results: " << passed << " passed, " << failed << " failed ===" << std::endl;
+    return failed > 0 ? 1 : 0;
+}