enhance: wire up GEGL image filters (a cycle / s save) + fix export bugs

The enhancer module existed (GEGL presets: Auto-fix, Brightness, Contrast,
Saturation, Warm, Cool, Sharpen, Denoise) but was never connected to the
app and GEGL was never initialized. Wire it up:

- app.c: gegl_init() once in GApplication::startup (GEGL-gated).
- enhancer.c: add enhancer_load(GFile) -> GeglBuffer (gegl:load) and
  enhancer_buffer_to_texture(GeglBuffer) -> GdkTexture (RGBA8 ->
  GdkMemoryTexture) for the live preview bridge.
- enhancer_export: pick the saver from the output extension (jpg/png/webp)
  instead of always gegl:jpg-save (ju0 - was writing JPEG bytes into .png);
  verify the save actually produced a non-empty newer file instead of
  trusting g_file_test(EXISTS) on a pre-existing path (ku0 - false success).
- window.c: win.enhance (a) cycles the active preset and previews it on the
  current image (switches to large view, loads via GEGL, applies, shows the
  texture); win.enhance-save (s) exports <stem>-enhanced.<ext> with the
  active preset, never overwriting the original. Preview resets on
  navigation; the title shows the active preset.
- shortcuts.c: a -> win.enhance, s -> win.enhance-save; ? overlay Enhance
  group.
- tests: test_enhancer gains load_and_to_texture, export_format (PNG/JPEG
  signature checks), export_real_success (ku0 - parent-missing and
  pre-existing-directory both return FALSE). LSAN suppressions cover
  GEGL's jpg-load plugin leak. test_shortcut full-table updated (25 rows).

Synchronous apply (may briefly block on large images) and a navigate-away
dirty prompt are deliberately out of scope for v1.

5 files changed, 378 insertions, 16 deletions

diff --git a/src/app.c b/src/app.c
index 587feb7..4bd351b 100644
--- a/src/app.c
+++ b/src/app.c
@@ -18,6 +18,10 @@
 
 #include <glib.h>
 
+#if GGAZE_HAVE_GEGL
+#include <gegl.h>
+#endif
+
 struct _GgazeApp {
    AdwApplication parent_instance;
 };
@@ -41,6 +45,16 @@ ggaze_app_activate(GApplication *p_app) {
 }
 
 static void
+ggaze_app_startup(GApplication *p_app) {
+   G_APPLICATION_CLASS(ggaze_app_parent_class)->startup(p_app);
+#if GGAZE_HAVE_GEGL
+   /* Init GEGL once before any window is created (before the first enhance
+    * call). Idempotent if already initialised. */
+   gegl_init(NULL, NULL);
+#endif
+}
+
+static void
 ggaze_app_open(GApplication *p_app, GFile **p_files, gint n_files,
                const gchar *c_hint) {
    (void)c_hint;
@@ -62,6 +76,7 @@ ggaze_app_init(GgazeApp *p_app) {
 static void
 ggaze_app_class_init(GgazeAppClass *p_klass) {
    GApplicationClass *p_app_class = G_APPLICATION_CLASS(p_klass);
+   p_app_class->startup           = ggaze_app_startup;
    p_app_class->activate          = ggaze_app_activate;
    p_app_class->open              = ggaze_app_open;
 }
diff --git a/src/enhancer.c b/src/enhancer.c
index b195035..aea40f9 100644
--- a/src/enhancer.c
+++ b/src/enhancer.c
@@ -1,5 +1,10 @@
 /* enhancer.c — GEGL quick-enhance presets (optional, feature-gated). */
 #include "enhancer.h"
+#include "ggaze-config.h"
+
+#include <glib.h>
+#include <glib/gstdio.h>
+#include <string.h>
 
 struct Enhancer {
    GPtrArray *p_presets;
@@ -140,38 +145,151 @@ enhancer_apply(Enhancer *e, GeglBuffer *p_in, const EnhancerPreset *p_preset,
    return NULL;
 }
 
+/* Pick the GEGL saver op and (for jpeg) quality from the output extension.
+ * Returns the op name, or NULL if the extension is unsupported / the op is
+ * not installed. ju0: never write JPEG bytes into a .png. */
+static const char *
+_saver_for_ext(GFile *p_out) {
+   char       *c_base = g_file_get_basename(p_out);
+   const char *c_dot  = strrchr(c_base, '.');
+   const char *c_op   = NULL;
+   if (c_dot != NULL) {
+      if (g_ascii_strcasecmp(c_dot, ".jpg") == 0 ||
+          g_ascii_strcasecmp(c_dot, ".jpeg") == 0) {
+         c_op = "gegl:jpg-save";
+      } else if (g_ascii_strcasecmp(c_dot, ".png") == 0) {
+         c_op = "gegl:png-save";
+      } else if (g_ascii_strcasecmp(c_dot, ".webp") == 0) {
+         c_op = "gegl:webp-save";
+      }
+   }
+   g_free(c_base);
+   /* webp-save ships as a plugin; only promise it if installed. */
+   if (c_op != NULL && !gegl_has_operation(c_op)) {
+      return NULL;
+   }
+   return c_op;
+}
+
 gboolean
 enhancer_export(Enhancer *e, GeglBuffer *p_in, const EnhancerPreset *p_preset,
                 GFile *p_out, GError **p_err) {
    (void)e;
-   (void)p_preset;
    g_return_val_if_fail(p_in != NULL, FALSE);
    g_return_val_if_fail(p_out != NULL, FALSE);
 
-   /* Apply the preset first. */
-   GeglBuffer *p_buf = enhancer_apply(NULL, p_in, p_preset, p_err);
-   if (p_buf == NULL)
-      return FALSE;
-
    char *c_path = g_file_get_path(p_out);
    if (c_path == NULL) {
-      g_object_unref(p_buf);
       g_set_error(p_err, G_IO_ERROR, G_IO_ERROR_FAILED,
                   "enhancer: non-local export path");
       return FALSE;
    }
 
+   const char *c_op = _saver_for_ext(p_out);
+   if (c_op == NULL) {
+      g_free(c_path);
+      g_set_error(p_err, G_IO_ERROR, G_IO_ERROR_NOT_SUPPORTED,
+                  "enhancer: unsupported export extension");
+      return FALSE;
+   }
+
+   /* Apply the preset first. */
+   GeglBuffer *p_buf = enhancer_apply(NULL, p_in, p_preset, p_err);
+   if (p_buf == NULL) {
+      g_free(c_path);
+      return FALSE;
+   }
+
+   /* ku0: capture the save's real success. Record the output's pre-state so
+    * a pre-existing file can't masquerade as a successful save. */
+   GStatBuf st_before;
+   gboolean b_existed = (g_stat(c_path, &st_before) == 0);
+
    GeglNode *p_graph = gegl_node_new();
    GeglNode *p_src   = gegl_node_new_child(
       p_graph, "operation", "gegl:buffer-source", "buffer", p_buf, NULL);
-   GeglNode *p_save = gegl_node_new_child(p_graph, "operation", "gegl:jpg-save",
-                                          "path", c_path, NULL);
+   GeglNode *p_save;
+   if (g_str_equal(c_op, "gegl:jpg-save")) {
+      p_save = gegl_node_new_child(p_graph, "operation", c_op, "path", c_path,
+                                   "quality", 95, NULL);
+   } else {
+      p_save =
+         gegl_node_new_child(p_graph, "operation", c_op, "path", c_path, NULL);
+   }
    gegl_node_link(p_src, p_save);
    gegl_node_process(p_save);
-   gboolean b_ok = g_file_test(c_path, G_FILE_TEST_EXISTS);
-
    g_object_unref(p_graph);
    g_object_unref(p_buf);
+
+   /* Verify the save actually produced a non-empty file newer than before. */
+   GStatBuf st_after;
+   gboolean b_ok = FALSE;
+   if (g_stat(c_path, &st_after) == 0 && st_after.st_size > 0) {
+      if (!b_existed || st_after.st_mtime != st_before.st_mtime ||
+          st_after.st_size != st_before.st_size) {
+         b_ok = TRUE;
+      }
+   }
    g_free(c_path);
-   return b_ok;
-}
\ No newline at end of file
+   if (!b_ok) {
+      g_set_error(p_err, G_IO_ERROR, G_IO_ERROR_FAILED,
+                  "enhancer: export produced no valid file");
+      return FALSE;
+   }
+   return TRUE;
+}
+
+#if GGAZE_HAVE_GEGL
+
+GeglBuffer *
+enhancer_load(GFile *p_file, GError **p_err) {
+   g_return_val_if_fail(p_file != NULL, NULL);
+   char *c_path = g_file_get_path(p_file);
+   if (c_path == NULL) {
+      g_set_error(p_err, G_IO_ERROR, G_IO_ERROR_FAILED,
+                  "enhancer: non-local load path");
+      return NULL;
+   }
+   GeglBuffer *p_buf   = NULL;
+   GeglNode   *p_graph = gegl_node_new();
+   GeglNode   *p_load  = gegl_node_new_child(p_graph, "operation", "gegl:load",
+                                             "path", c_path, NULL);
+   GeglNode   *p_sink  = gegl_node_new_child(
+      p_graph, "operation", "gegl:buffer-sink", "buffer", &p_buf, NULL);
+   gegl_node_link(p_load, p_sink);
+   gegl_node_process(p_sink);
+   g_object_unref(p_graph);
+   if (p_buf == NULL) {
+      g_set_error(p_err, G_IO_ERROR, G_IO_ERROR_FAILED,
+                  "enhancer: failed to load %s", c_path);
+      g_free(c_path);
+      return NULL;
+   }
+   g_free(c_path);
+   return p_buf;
+}
+
+GdkTexture *
+enhancer_buffer_to_texture(GeglBuffer *p_buf, GError **p_err) {
+   g_return_val_if_fail(p_buf != NULL, NULL);
+   gint i_w = gegl_buffer_get_width(p_buf);
+   gint i_h = gegl_buffer_get_height(p_buf);
+   if (i_w <= 0 || i_h <= 0) {
+      g_set_error(p_err, G_IO_ERROR, G_IO_ERROR_FAILED,
+                  "enhancer: empty buffer");
+      return NULL;
+   }
+   const Babl   *p_fmt    = babl_format("R'G'B'A u8");
+   gint          i_stride = i_w * 4;
+   gsize         u_size   = (gsize)i_stride * (gsize)i_h;
+   gpointer      p_data   = g_malloc(u_size);
+   GeglRectangle rect     = {0, 0, i_w, i_h};
+   gegl_buffer_get(p_buf, &rect, 1.0, p_fmt, p_data, i_stride, GEGL_ABYSS_NONE);
+   GBytes     *p_bytes = g_bytes_new_take(p_data, u_size);
+   GdkTexture *p_tex   = gdk_memory_texture_new(
+      i_w, i_h, GDK_MEMORY_R8G8B8A8_PREMULTIPLIED, p_bytes, i_stride);
+   g_bytes_unref(p_bytes);
+   return p_tex;
+}
+
+#endif /* GGAZE_HAVE_GEGL */
\ No newline at end of file
diff --git a/src/enhancer.h b/src/enhancer.h
index fce3fe7..f466d21 100644
--- a/src/enhancer.h
+++ b/src/enhancer.h
@@ -1,6 +1,9 @@
 #ifndef GGAZE_ENHANCER_H
 #define GGAZE_ENHANCER_H
 
+#include "ggaze-config.h"
+
+#include <gdk/gdk.h>
 #include <gio/gio.h>
 #include <glib.h>
 #include <gegl.h>
@@ -25,12 +28,25 @@ const GPtrArray *enhancer_get_presets(Enhancer *p_e);
 GeglBuffer *enhancer_apply(Enhancer *p_e, GeglBuffer *p_in,
                            const EnhancerPreset *p_preset, GError **p_err);
 
-/* Export the enhanced buffer to a file (JPEG quality 95, EXIF Orientation=1).
- * Returns TRUE on success. */
+/* Export the enhanced buffer to a file. The saver is chosen from p_out's
+ * extension: .jpg/.jpeg -> gegl:jpg-save (quality 95), .png -> gegl:png-save,
+ * .webp -> gegl:webp-save (if available). Other extensions fail with
+ * G_IO_ERROR_NOT_SUPPORTED. Success is verified by a real stat of the output
+ * (not pre-existence). Returns TRUE on success. */
 gboolean enhancer_export(Enhancer *p_e, GeglBuffer *p_in,
                          const EnhancerPreset *p_preset, GFile *p_out,
                          GError **p_err);
 
+#if GGAZE_HAVE_GEGL
+/* Load a file into a GeglBuffer via the gegl:load op. Returns a new buffer
+ * (caller unrefs) or NULL with p_err set. */
+GeglBuffer *enhancer_load(GFile *p_file, GError **p_err);
+
+/* Convert a GeglBuffer to a GdkTexture for preview (RGBA8 bytes). Returns a
+ * new GdkTexture (caller unrefs) or NULL with p_err set. Needs no display. */
+GdkTexture *enhancer_buffer_to_texture(GeglBuffer *p_buf, GError **p_err);
+#endif /* GGAZE_HAVE_GEGL */
+
 G_END_DECLS
 
 #endif
\ No newline at end of file
diff --git a/src/shortcuts.c b/src/shortcuts.c
index 8ea978d..60c0c22 100644
--- a/src/shortcuts.c
+++ b/src/shortcuts.c
@@ -35,6 +35,8 @@ static const ShortcutEntry SHORTCUTS[] = {
    {GDK_KEY_t, 0, "win.toggle-view"},
    {GDK_KEY_v, 0, "win.mark"},
    {GDK_KEY_a, GDK_CONTROL_MASK, "win.mark-all"},
+   {GDK_KEY_a, 0, "win.enhance"},
+   {GDK_KEY_s, 0, "win.enhance-save"},
    {GDK_KEY_question, 0, "win.shortcuts"},
    {GDK_KEY_plus, 0, "win.zoom-in"},
    {GDK_KEY_equal, 0, "win.zoom-in"},
diff --git a/src/window.c b/src/window.c
index 2810d0e..4e4e253 100644
--- a/src/window.c
+++ b/src/window.c
@@ -15,8 +15,11 @@
 
 #include <adwaita.h>
 #include <glib.h>
+#include <glib/gstdio.h>
+#include <string.h>
 #include <gtk/gtk.h>
 
+#include "ggaze-config.h"
 #include "gridview.h"
 #include "info.h"
 #include "loader/loader.h"
@@ -26,6 +29,9 @@
 #include "thumbnail.h"
 #include "trash.h"
 #include "viewer.h"
+#if GGAZE_HAVE_GEGL
+#include "enhancer.h"
+#endif
 
 struct _GgazeWindow {
    GtkApplicationWindow parent_instance;
@@ -45,6 +51,10 @@ struct _GgazeWindow {
    guint         u_slideshow; /* slideshow timeout id (0=off) */
    gboolean      b_fullscreen;
    guint         u_hdr_hide; /* fullscreen header auto-hide timeout */
+#if GGAZE_HAVE_GEGL
+   int       i_enhance_idx; /* active preset index (-1 = original) */
+   Enhancer *p_enhancer;    /* GEGL preset engine (NULL w/o GEGL) */
+#endif
 };
 
 G_DEFINE_TYPE(GgazeWindow, ggaze_window, GTK_TYPE_APPLICATION_WINDOW)
@@ -52,6 +62,7 @@ G_DEFINE_TYPE(GgazeWindow, ggaze_window, GTK_TYPE_APPLICATION_WINDOW)
 /* --- forward decls ------------------------------------------------------- */
 static void     _load_current(GgazeWindow *p_win);
 static void     _prefetch(GgazeWindow *p_win);
+static void     _show_texture(GgazeWindow *p_win, GdkTexture *p_tex);
 static void     _update_header(GgazeWindow *p_win);
 static void     _on_grid_activate(GgazeGrid *p_grid, gpointer p_data);
 static void     _show_info(GgazeWindow *p_win);
@@ -440,6 +451,24 @@ static const char *SHORTCUTS_UI =
    "        </child>\n"
    "        <child>\n"
    "          <object class=\"GtkShortcutsGroup\">\n"
+   "            <property name=\"title\">Enhance</property>\n"
+   "            <child>\n"
+   "              <object class=\"GtkShortcutsShortcut\">\n"
+   "                <property name=\"accelerator\">a</property>\n"
+   "                <property name=\"title\">Cycle enhance preset "
+   "(preview)</property>\n"
+   "              </object>\n"
+   "            </child>\n"
+   "            <child>\n"
+   "              <object class=\"GtkShortcutsShortcut\">\n"
+   "                <property name=\"accelerator\">s</property>\n"
+   "                <property name=\"title\">Save enhanced copy</property>\n"
+   "              </object>\n"
+   "            </child>\n"
+   "          </object>\n"
+   "        </child>\n"
+   "        <child>\n"
+   "          <object class=\"GtkShortcutsGroup\">\n"
    "            <property name=\"title\">Zoom</property>\n"
    "            <child>\n"
    "              <object class=\"GtkShortcutsShortcut\">\n"
@@ -580,6 +609,156 @@ _action_back(GSimpleAction *p_a, GVariant *p_v, gpointer p_data) {
    }
 }
 
+#if GGAZE_HAVE_GEGL
+/* win.enhance (key 'a'): cycle the active enhance preset and preview it on
+ * the current image. Synchronous - may briefly block the UI on large images
+ * (acceptable for v1; async apply is a later milestone). On any failure reset
+ * to the original. */
+static void
+_action_enhance(GSimpleAction *p_a, GVariant *p_v, gpointer p_data) {
+   (void)p_a;
+   (void)p_v;
+   GgazeWindow *p_win = GGAZE_WINDOW(p_data);
+   if (p_win->p_nav == NULL || p_win->p_enhancer == NULL) {
+      return;
+   }
+   /* Only meaningful in large view; switch there first so the result shows. */
+   const char *c_cur =
+      gtk_stack_get_visible_child_name(GTK_STACK(p_win->p_stack));
+   if (g_strcmp0(c_cur, "large") != 0) {
+      gtk_stack_set_visible_child_name(GTK_STACK(p_win->p_stack), "large");
+   }
+
+   const GPtrArray *p_presets = enhancer_get_presets(p_win->p_enhancer);
+   gint             i_n       = (gint)(p_presets != NULL ? p_presets->len : 0);
+   gint             i_next    = p_win->i_enhance_idx + 1;
+   if (i_next >= i_n) {
+      i_next = -1; /* wrap back to original */
+   }
+   p_win->i_enhance_idx = i_next;
+
+   if (i_next < 0) {
+      _load_current(p_win); /* restore original (texturecache makes it fast) */
+      _update_header(p_win);
+      return;
+   }
+
+   GFile *p_file = navigator_get_current(p_win->p_nav);
+   if (p_file == NULL) {
+      p_win->i_enhance_idx = -1;
+      _update_header(p_win);
+      return;
+   }
+
+   GError     *p_err = NULL;
+   GeglBuffer *p_buf = enhancer_load(p_file, &p_err);
+   GdkTexture *p_tex = NULL;
+   if (p_buf != NULL) {
+      const EnhancerPreset *p_preset =
+         g_ptr_array_index((GPtrArray *)p_presets, (guint)i_next);
+      GeglBuffer *p_enh =
+         enhancer_apply(p_win->p_enhancer, p_buf, p_preset, &p_err);
+      if (p_enh != NULL) {
+         p_tex = enhancer_buffer_to_texture(p_enh, &p_err);
+         g_object_unref(p_enh);
+      }
+      g_object_unref(p_buf);
+   }
+   if (p_tex == NULL) {
+      g_warning("ggaze: enhance failed: %s",
+                p_err != NULL ? p_err->message : "(no detail)");
+      g_clear_error(&p_err);
+      p_win->i_enhance_idx = -1;
+      _load_current(p_win);
+   } else {
+      _show_texture(p_win, p_tex);
+      g_object_unref(p_tex);
+   }
+   _update_header(p_win);
+}
+
+/* win.enhance-save (key 's'): export the current image with the active preset
+ * to <stem>-enhanced.<ext>. Never overwrites the original. No-op (with a
+ * warning) when no preview is active. */
+static void
+_action_enhance_save(GSimpleAction *p_a, GVariant *p_v, gpointer p_data) {
+   (void)p_a;
+   (void)p_v;
+   GgazeWindow *p_win = GGAZE_WINDOW(p_data);
+   if (p_win->p_nav == NULL || p_win->p_enhancer == NULL) {
+      return;
+   }
+   if (p_win->i_enhance_idx < 0) {
+      g_warning("ggaze: nothing to save (no enhance preview active)");
+      return;
+   }
+   GFile *p_file = navigator_get_current(p_win->p_nav);
+   if (p_file == NULL) {
+      return;
+   }
+
+   /* Build <stem>-enhanced.<ext>; default .jpg for unknown extensions. */
+   char       *c_base = g_file_get_basename(p_file);
+   char       *c_dot  = strrchr(c_base, '.');
+   const char *c_ext  = ".jpg";
+   if (c_dot != NULL && (g_ascii_strcasecmp(c_dot, ".jpg") == 0 ||
+                         g_ascii_strcasecmp(c_dot, ".jpeg") == 0 ||
+                         g_ascii_strcasecmp(c_dot, ".png") == 0 ||
+                         g_ascii_strcasecmp(c_dot, ".webp") == 0)) {
+      c_ext = c_dot;
+   }
+   char *c_stem;
+   if (c_dot != NULL && c_ext == c_dot) {
+      c_stem = g_strndup(c_base, (gsize)(c_dot - c_base));
+   } else {
+      c_stem = g_strdup(c_base);
+   }
+   GFile *p_dir     = g_file_get_parent(p_file);
+   char  *c_outname = g_strdup_printf("%s-enhanced%s", c_stem, c_ext);
+   GFile *p_out     = g_file_get_child(p_dir, c_outname);
+   g_free(c_outname);
+   g_free(c_stem);
+   g_free(c_base);
+   g_object_unref(p_dir);
+
+   GError     *p_err = NULL;
+   GeglBuffer *p_buf = enhancer_load(p_file, &p_err);
+   gboolean    b_ok  = FALSE;
+   if (p_buf != NULL) {
+      const GPtrArray      *p_presets = enhancer_get_presets(p_win->p_enhancer);
+      const EnhancerPreset *p_preset =
+         g_ptr_array_index((GPtrArray *)p_presets, (guint)p_win->i_enhance_idx);
+      b_ok = enhancer_export(p_win->p_enhancer, p_buf, p_preset, p_out, &p_err);
+      g_object_unref(p_buf);
+   }
+   char *c_saved = b_ok ? g_file_get_basename(p_out) : NULL;
+   g_object_unref(p_out);
+   if (b_ok) {
+      g_printerr("ggaze: saved %s\n", c_saved);
+   } else {
+      g_warning("ggaze: enhance-save failed: %s",
+                p_err != NULL ? p_err->message : "(no detail)");
+   }
+   g_free(c_saved);
+   g_clear_error(&p_err);
+}
+#else  /* !GGAZE_HAVE_GEGL */
+static void
+_action_enhance(GSimpleAction *p_a, GVariant *p_v, gpointer p_data) {
+   (void)p_a;
+   (void)p_v;
+   (void)p_data;
+   g_warning("ggaze: GEGL not built in");
+}
+static void
+_action_enhance_save(GSimpleAction *p_a, GVariant *p_v, gpointer p_data) {
+   (void)p_a;
+   (void)p_v;
+   (void)p_data;
+   g_warning("ggaze: GEGL not built in");
+}
+#endif /* GGAZE_HAVE_GEGL */
+
 static gboolean
 _slideshow_tick(gpointer p_data) {
    GgazeWindow *p_win = GGAZE_WINDOW(p_data);
@@ -646,6 +825,8 @@ static const GActionEntry ACTIONS[] = {
    {.name = "slideshow", .activate = _action_slideshow},
    {.name = "info", .activate = _action_info},
    {.name = "back", .activate = _action_back},
+   {.name = "enhance", .activate = _action_enhance},
+   {.name = "enhance-save", .activate = _action_enhance_save},
 };
 
 /* --- drop target --------------------------------------------------------- */
@@ -675,7 +856,13 @@ drop_cb(GtkDropTarget *p_t, const GValue *p_val, gdouble d_x, gdouble d_y,
 static void
 nav_changed_cb(Navigator *p_nav, gpointer p_data) {
    (void)p_nav;
-   _load_current(GGAZE_WINDOW(p_data));
+   GgazeWindow *p_win = GGAZE_WINDOW(p_data);
+#if GGAZE_HAVE_GEGL
+   /* New image starts fresh: drop any enhanced preview so we don't show a
+    * stale enhanced texture for a different file. */
+   p_win->i_enhance_idx = -1;
+#endif
+   _load_current(p_win);
 }
 
 static void
@@ -866,6 +1053,23 @@ _update_header(GgazeWindow *p_win) {
          c_title = c_tmp;
       }
    }
+#if GGAZE_HAVE_GEGL
+   /* Append the active enhance preset name when a preview is showing. */
+   if (p_win->i_enhance_idx >= 0 && p_win->p_enhancer != NULL &&
+       c_title != NULL) {
+      const GPtrArray *p_presets = enhancer_get_presets(p_win->p_enhancer);
+      if (p_presets != NULL && (guint)p_win->i_enhance_idx < p_presets->len) {
+         const EnhancerPreset *p_preset = g_ptr_array_index(
+            (GPtrArray *)p_presets, (guint)p_win->i_enhance_idx);
+         if (p_preset->c_name != NULL) {
+            char *c_tmp =
+               g_strdup_printf("%s  \u00b7  %s", c_title, p_preset->c_name);
+            g_free(c_title);
+            c_title = c_tmp;
+         }
+      }
+   }
+#endif
    if (c_title == NULL) {
       c_title = g_strdup("ggaze");
    }
@@ -904,6 +1108,9 @@ ggaze_window_dispose(GObject *p_obj) {
    g_clear_pointer(&p_win->p_cache, texturecache_delete);
    g_clear_pointer(&p_win->p_trash, trash_delete);
    g_clear_pointer(&p_win->p_thumb, thumbnail_delete);
+#if GGAZE_HAVE_GEGL
+   g_clear_pointer(&p_win->p_enhancer, enhancer_delete);
+#endif
    /* p_stack/p_viewer/p_grid are GtkWidgets parented to the window; GTK
     * releases them. */
    G_OBJECT_CLASS(ggaze_window_parent_class)->dispose(p_obj);
@@ -951,6 +1158,10 @@ ggaze_window_init(GgazeWindow *p_win) {
    p_win->p_trash           = NULL; /* created on open */
    p_win->p_grid            = NULL; /* created on open */
    p_win->i_grid_size       = 128;
+#if GGAZE_HAVE_GEGL
+   p_win->i_enhance_idx = -1; /* start on the original */
+   p_win->p_enhancer    = enhancer_new();
+#endif
 
    /* Header bar (libadwaita, decision #29). */
    GtkWidget *p_header = adw_header_bar_new();