From c05e83ec753d2f85a90ef6ea1150a80d19461b85 Mon Sep 17 00:00:00 2001
From: Bill <wholcombe@cnm.edu>
Date: Tue, 17 Feb 2026 21:50:51 -0700
Subject: [PATCH] Step 647: self-modification safety guard

---
 editor/CMakeLists.txt                    |  9 ++++++++
 editor/src/SelfModificationSafetyGuard.h | 28 ++++++++++++++++++++++++
 editor/tests/step647_test.cpp            | 25 +++++++++++++++++++++
 progress.md                              | 24 ++++++++++++++++++++
 4 files changed, 86 insertions(+)
 create mode 100644 editor/src/SelfModificationSafetyGuard.h
 create mode 100644 editor/tests/step647_test.cpp

diff --git a/editor/CMakeLists.txt b/editor/CMakeLists.txt
index 904f7cf..4d9bd56 100644
--- a/editor/CMakeLists.txt
+++ b/editor/CMakeLists.txt
@@ -4702,4 +4702,13 @@ target_link_libraries(step646_test PRIVATE
     tree_sitter_javascript tree_sitter_typescript
     tree_sitter_java tree_sitter_rust tree_sitter_go)
 
+add_executable(step647_test tests/step647_test.cpp)
+target_include_directories(step647_test PRIVATE src)
+target_link_libraries(step647_test PRIVATE
+    nlohmann_json::nlohmann_json
+    unofficial::tree-sitter::tree-sitter
+    tree_sitter_python tree_sitter_cpp tree_sitter_elisp
+    tree_sitter_javascript tree_sitter_typescript
+    tree_sitter_java tree_sitter_rust tree_sitter_go)
+
 # Step 12: Dear ImGui shell scaffolding created (main.cpp exists but not built due to dependencies)
diff --git a/editor/src/SelfModificationSafetyGuard.h b/editor/src/SelfModificationSafetyGuard.h
new file mode 100644
index 0000000..51e158f
--- /dev/null
+++ b/editor/src/SelfModificationSafetyGuard.h
@@ -0,0 +1,28 @@
+#pragma once
+// Step 647: Self-modification safety guard
+
+#include <string>
+#include <vector>
+
+class SelfModificationSafetyGuard {
+public:
+    static bool isLiveBinaryPath(const std::string& filePath,
+                                 const std::vector<std::string>& liveRoots) {
+        for (const auto& root : liveRoots) {
+            if (!root.empty() && filePath.rfind(root, 0) == 0) return true;
+        }
+        return false;
+    }
+
+    static bool allowMutation(const std::string& filePath,
+                              const std::vector<std::string>& liveRoots,
+                              std::string* reason) {
+        if (!reason) return false;
+        reason->clear();
+        if (isLiveBinaryPath(filePath, liveRoots)) {
+            *reason = "Cannot mutate live binary - use a build/restart cycle.";
+            return false;
+        }
+        return true;
+    }
+};
diff --git a/editor/tests/step647_test.cpp b/editor/tests/step647_test.cpp
new file mode 100644
index 0000000..da5960d
--- /dev/null
+++ b/editor/tests/step647_test.cpp
@@ -0,0 +1,25 @@
+// Step 647: Self-modification safety guard (12 tests)
+
+#include "SelfModificationSafetyGuard.h"
+#include <iostream>
+
+static int p=0,f=0;
+#define T(n) { std::cout<<"  "<<#n<<"... "; }
+#define P() { std::cout<<"PASS\n"; ++p; }
+#define F(m) { std::cout<<"FAIL: "<<m<<"\n"; ++f; }
+#define C(c,m) if(!(c)){F(m);return;}
+
+void t1(){T(live_path_detected_for_editor_src);C(SelfModificationSafetyGuard::isLiveBinaryPath("editor/src/main.cpp",{"editor/src"}),"should detect live path");P();}
+void t2(){T(non_live_path_not_detected);C(!SelfModificationSafetyGuard::isLiveBinaryPath("docs/readme.md",{"editor/src"}),"should not detect");P();}
+void t3(){T(empty_live_roots_allows_non_detection);C(!SelfModificationSafetyGuard::isLiveBinaryPath("editor/src/main.cpp",{}),"empty roots should not match");P();}
+void t4(){T(allow_mutation_true_for_non_live_file);std::string r;C(SelfModificationSafetyGuard::allowMutation("docs/readme.md",{"editor/src"},&r),"should allow");P();}
+void t5(){T(allow_mutation_false_for_live_file);std::string r;C(!SelfModificationSafetyGuard::allowMutation("editor/src/main.cpp",{"editor/src"},&r),"should block");P();}
+void t6(){T(block_reason_contains_required_message);std::string r;SelfModificationSafetyGuard::allowMutation("editor/src/main.cpp",{"editor/src"},&r);C(r.find("Cannot mutate live binary")!=std::string::npos,"reason missing");P();}
+void t7(){T(allow_mutation_clears_reason_on_success);std::string r="x";SelfModificationSafetyGuard::allowMutation("docs/x",{"editor/src"},&r);C(r.empty(),"reason should clear");P();}
+void t8(){T(null_reason_pointer_rejected);C(!SelfModificationSafetyGuard::allowMutation("docs/x",{"editor/src"},nullptr),"null reason should fail");P();}
+void t9(){T(multi_root_live_match_detected);C(SelfModificationSafetyGuard::isLiveBinaryPath("editor/tests/a.cpp",{"editor/src","editor/tests"}),"multi-root should match");P();}
+void t10(){T(prefix_match_respects_root_start);C(!SelfModificationSafetyGuard::isLiveBinaryPath("tmp/editor/src/main.cpp",{"editor/src"}),"must match prefix");P();}
+void t11(){T(empty_path_is_allowed);std::string r;C(SelfModificationSafetyGuard::allowMutation("",{"editor/src"},&r),"empty path should allow");P();}
+void t12(){T(root_empty_is_ignored);C(!SelfModificationSafetyGuard::isLiveBinaryPath("editor/src/main.cpp",{""}),"empty root ignored");P();}
+
+int main(){std::cout<<"Step 647: Self-modification safety guard\n";t1();t2();t3();t4();t5();t6();t7();t8();t9();t10();t11();t12();std::cout<<"\nResults: "<<p<<"/"<<(p+f)<<" passed\n";return f?1:0;}
diff --git a/progress.md b/progress.md
index ee57b0b..fb1bea5 100644
--- a/progress.md
+++ b/progress.md
@@ -13252,3 +13252,27 @@ results, summary counters, completion status, and failure-to-source linking.
 - `editor/src/InEditorTestRunnerModel.h` (`40` <= `600`)
 - `editor/tests/step646_test.cpp` within test-file size guidance (`25` lines)
 - Header-only architecture and naming conventions remain aligned with `ARCHITECTURE.md`
+
+### Step 647: Self-modification safety guard
+**Status:** PASS (12/12 tests)
+
+Adds a self-modification guard for live editor-binary paths with explicit block
+reason messaging and allow/block decision helpers for mutation requests.
+
+**Files added:**
+- `editor/src/SelfModificationSafetyGuard.h` - live-binary mutation guard model
+- `editor/tests/step647_test.cpp` - 12 tests for path matching, block reasons, and edges
+
+**Files modified:**
+- `editor/CMakeLists.txt` - `step647_test` target
+
+**Verification run:**
+- `cmake -S editor -B editor/build-native` - PASS
+- `cmake --build editor/build-native --target step647_test step646_test` - PASS
+- `./editor/build-native/step647_test` - PASS (12/12)
+- `./editor/build-native/step646_test` - PASS (12/12) regression coverage
+
+**Architecture gate check:**
+- `editor/src/SelfModificationSafetyGuard.h` (`28` <= `600`)
+- `editor/tests/step647_test.cpp` within test-file size guidance (`25` lines)
+- Header-only architecture and naming conventions remain aligned with `ARCHITECTURE.md`