walkdir: navigator, shortcuts, window wiring, drop target, tests (ht0)

M2 (task ht0): walk the directory.

- src/navigator.{c,h}: GObject (no GtkWidget) holding the folder listing —
  image-MIME filter + extension fallback, hide-RAW-sidecars (decision #33),
  sort name/time/size, cursor + prev/next/wrap, path-based marks (survive
  re-sort, pruned on rescan/monitor, cleared on remove), nearest-fallback,
  GFileMonitor debounced 250ms (decision #28), 'changed' signal. 92% gcov.
- src/shortcuts.{c,h}: GtkShortcutController (MANAGED) binding h/l/Left/Right/
  g/G/o/q to win.* actions; one table all milestones add to.
- src/window.{c,h}: open file->parent+current / folder->first; h/l/g/G actions
  -> nav -> load -> viewer; single GCancellable last-write-wins (g_file_equal
  guard for M3 async); header title 'filename · n/total'; GtkDropTarget
  (GDK_TYPE_FILE_LIST, many->first, decision Z); GtkFileDialog open.
- data/gschema: add hide-raw-sidecars key.
- tests: unit test_navigator (12 subtests), integration test_walk_folder
  (temp fixtures walk + ./sample-images skip-if-absent). 8/8 green; ASan clean
  (GIO_USE_VFS=local in fixtures_env).

Fixed during this milestone: a UAF (borrowed c_name used after unref), a
cancellable double-ref leak, time::modified UINT64 vs INT64, and several
test-harness leaks. Sub-agent review issues addressed (mark pruning on
rescan/monitor, remove-before-cursor test, recursive temp-dir cleanup,
callback _cb naming, connect-before-mutate).

1 files changed, 14 insertions, 7 deletions

diff --git a/src/window.h b/src/window.h
index 5261a8f..10612db 100644
--- a/src/window.h
+++ b/src/window.h
@@ -6,9 +6,9 @@
  *
  * GgazeWindow : GtkApplicationWindow owns the layout: an AdwHeaderBar and a
  * GtkStack with two children (`grid`, `large`). The grid child is a placeholder
- * until M7; the large child is the GgazeViewer (M1). The window remembers the
- * current GFile so later milestones can build on it. See
- * docs/architecture.md "Responsibilities / window".
+ * until M7; the large child is the GgazeViewer (M1). M2 adds a Navigator over
+ * the current folder, a single GCancellable (last-write-wins), keybinding
+ * shortcuts, and a file/folder drop target. See docs/architecture.md.
  *
  * Copyright (c) 2026 ggaze contributors
  * SPDX-License-Identifier: GPL-3.0-or-later
@@ -27,10 +27,17 @@ G_DECLARE_FINAL_TYPE(GgazeWindow, ggaze_window, GGAZE, WINDOW,
 /* Construct a new window attached to p_app. */
 GgazeWindow *ggaze_window_new(GgazeApp *p_app);
 
-/* Remember p_file as the current file (or folder) and title the window with
- * its basename. The GFile reference is held until replaced or the window is
- * destroyed. Real file-vs-folder handling lands in M2. */
-void ggaze_window_open(GgazeWindow *p_win, GFile *p_file);
+/* Open p_arg (a file or a folder): for a file, list its parent folder with
+ * p_arg current; for a folder, list it with the first image current. Loads the
+ * current image into the viewer and switches the stack to "large". */
+void ggaze_window_open(GgazeWindow *p_win, GFile *p_arg);
+
+/* Navigation over the current folder (bound to h/l/Left/Right/g/G via
+ * shortcuts.c). No-ops if nothing is open. */
+void ggaze_window_prev(GgazeWindow *p_win);
+void ggaze_window_next(GgazeWindow *p_win);
+void ggaze_window_first(GgazeWindow *p_win);
+void ggaze_window_last(GgazeWindow *p_win);
 
 G_END_DECLS