test(cpp): add text_editor_smoke build gate for issue 0025

App minima (no abre ventana ImGui) que crea/settea/lee text_editor y registra
un watch sobre /tmp/fn_smoke_test.txt para confirmar que TextEditor.cpp del
vendor + text_editor.cpp + file_watcher.cpp enlazan correctamente. Activada
por defecto si la carpeta existe (no requiere la primitives_gallery).

Tambien anade flag FN_BUILD_GALLERY (OFF default) para no romper el build
cuando la primitives_gallery no esta presente — sus deps (button.cpp,
toolbar.cpp...) son sources untracked en algunas branches.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

cpp/CMakeLists.txt

@@ -115,6 +115,19 @@ if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/apps/shaders_lab/CMakeLists.txt)
     add_subdirectory(apps/shaders_lab)
 endif()
 
+# --- Primitives Gallery ---
+# Activado solo si la app esta presente Y todos sus deps tambien (button, toolbar...
+# son sources untracked en este worktree). Forzar con FN_BUILD_GALLERY=ON.
+if(FN_BUILD_GALLERY AND EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/apps/primitives_gallery/CMakeLists.txt)
+    add_subdirectory(apps/primitives_gallery)
+endif()
+
+# --- text_editor + file_watcher smoke test (issue 0025) ---
+# Build gate para validar que text_editor.cpp + file_watcher.cpp + vendor enlazan.
+if(EXISTS ${CMAKE_CURRENT_SOURCE_DIR}/apps/text_editor_smoke/CMakeLists.txt)
+    add_subdirectory(apps/text_editor_smoke)
+endif()
+
 # --- Registry Dashboard (lives in projects/fn_monitoring/apps/) ---
 set(_DASH_DIR ${CMAKE_SOURCE_DIR}/../projects/fn_monitoring/apps/registry_dashboard)
 if(EXISTS ${_DASH_DIR}/CMakeLists.txt)

cpp/apps/text_editor_smoke/CMakeLists.txt

@@ -0,0 +1,14 @@
+# Smoke test app para validar que text_editor + file_watcher compilan
+# y enlazan correctamente. NO es una app del registry, solo build gate
+# de las funciones nuevas del issue 0025. Sin ImGui events runtime — el
+# test crea, settea texto, polea y destruye en 1 frame headless (no abre ventana).
+
+add_imgui_app(text_editor_smoke
+    main.cpp
+    ${CMAKE_SOURCE_DIR}/functions/core/text_editor.cpp
+    ${CMAKE_SOURCE_DIR}/functions/core/file_watcher.cpp
+    ${CMAKE_SOURCE_DIR}/vendor/imgui_text_edit/TextEditor.cpp
+)
+target_include_directories(text_editor_smoke PRIVATE
+    ${CMAKE_SOURCE_DIR}/vendor/imgui_text_edit
+)

cpp/apps/text_editor_smoke/main.cpp

@@ -0,0 +1,64 @@
+// Smoke test (no GUI): compila y ejecuta brevemente las APIs nuevas del
+// issue 0025 para validar que el wrapper PIMPL del text_editor y el
+// file_watcher (inotify Linux / ReadDirectoryChangesW Win) enlazan.
+//
+// No abre ventana ImGui — solo crea / settea texto / lee / poll / destruye.
+
+#include "core/text_editor.h"
+#include "core/file_watcher.h"
+
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+#include <thread>
+#include <chrono>
+
+int main() {
+    // ----- text_editor -----
+    auto* ed = fn::text_editor_create(fn::CodeLang::GLSL);
+    if (!ed) { std::fprintf(stderr, "text_editor_create returned null\n"); return 1; }
+
+    fn::text_editor_set_text(ed, "void main(){}\n");
+    const char* got = fn::text_editor_get_text(ed);
+    std::printf("text_editor: get_text -> %zu bytes\n", got ? std::strlen(got) : 0u);
+
+    if (fn::text_editor_is_dirty(ed)) {
+        std::fprintf(stderr, "text_editor: dirty unexpected after set_text\n");
+        return 1;
+    }
+    fn::text_editor_destroy(ed);
+
+    // ----- file_watcher -----
+    const char* path = "/tmp/fn_smoke_test.txt";
+    std::remove(path);
+    {
+        FILE* f = std::fopen(path, "w"); std::fputs("init\n", f); std::fclose(f);
+    }
+
+    auto* fw = fn::file_watcher_create();
+    if (!fw) { std::fprintf(stderr, "file_watcher_create returned null\n"); return 1; }
+
+    if (!fn::file_watcher_add(fw, path)) {
+        std::fprintf(stderr, "file_watcher_add failed: %s\n", fn::file_watcher_last_error(fw));
+        // Aun asi continuamos: en CI sin inotify (raro) este test seria flaky.
+    }
+
+    // Modificar
+    {
+        FILE* f = std::fopen(path, "w"); std::fputs("changed\n", f); std::fclose(f);
+    }
+    std::this_thread::sleep_for(std::chrono::milliseconds(50));
+
+    auto evs = fn::file_watcher_poll(fw);
+    std::printf("file_watcher: %zu events\n", evs.size());
+    for (auto& e : evs) {
+        const char* kind = e.kind == fn::FileEvent::Modified ? "MOD"
+                          : e.kind == fn::FileEvent::Created ? "NEW" : "DEL";
+        std::printf("  [%s] %s\n", kind, e.path.c_str());
+    }
+
+    fn::file_watcher_destroy(fw);
+    std::remove(path);
+    std::printf("OK\n");
+    return 0;
+}