fix ui widgets

src/ui/ui_widgets.h

@@ -1,3 +1,70 @@
 #pragma once
-// ui_widgets.h - Removed: Clay handles all layout and widgets directly.
-// This file is kept empty for the unity build include order.
+// ui_widgets.h - Immediate-mode widgets built on top of Clay.
+//
+// Each widget function takes a unique string ID, the value to display/edit,
+// and returns whether the value was changed (or the widget was activated).
+// The caller owns all data — the widget layer only stores transient UI state
+// like which text field is focused or which dropdown is open.
+
+#include "ui/ui_core.h"
+#include "platform/platform.h"
+
+////////////////////////////////
+// Widget state (global, managed by widget layer)
+
+#define UI_WIDGET_MAX_DROPDOWN_ITEMS 32
+
+struct UI_WidgetState {
+    // Text input focus
+    uint32_t focused_id;       // Clay element ID hash of the focused text input (0 = none)
+    int32_t  cursor_pos;       // Cursor position in focused text input
+    F32      cursor_blink;     // Blink timer (seconds)
+
+    // Dropdown
+    uint32_t open_dropdown_id; // Clay element ID hash of the open dropdown (0 = none)
+
+    // Input events for this frame
+    PlatformInputEvents input;
+
+    // Click detection
+    B32 mouse_down;
+    B32 was_mouse_down;
+    B32 mouse_clicked; // true on the frame mouse transitions from up->down
+};
+
+extern UI_WidgetState g_wstate;
+
+// Call once at startup
+void ui_widgets_init();
+
+// Call each frame before building widgets. Pass in the frame's input events.
+void ui_widgets_begin_frame(PlatformInputEvents input, B32 mouse_down, B32 was_mouse_down);
+
+// Reset per-frame text input display buffer allocator (called by begin_frame, but
+// can also be called manually if needed)
+void ui_text_input_reset_display_bufs();
+
+////////////////////////////////
+// Widgets
+// All IDs must be unique string literals (passed to CLAY_ID internally).
+
+// Simple label
+void ui_label(const char *id, const char *text);
+
+// Clickable button. Returns true on the frame it was clicked.
+B32 ui_button(const char *id, const char *text);
+
+// Checkbox. Toggles *value on click. Returns true if value changed.
+B32 ui_checkbox(const char *id, const char *label, B32 *value);
+
+// Radio button group. Sets *selected to the clicked index. Returns true if changed.
+// options is an array of label strings, count is the number of options.
+B32 ui_radio_group(const char *id, const char **options, S32 count, S32 *selected);
+
+// Single-line text input. Edits buf in-place (null-terminated, max buf_size-1 chars).
+// Returns true if the text changed this frame.
+B32 ui_text_input(const char *id, char *buf, S32 buf_size);
+
+// Dropdown / combo box. Sets *selected to chosen index. Returns true if changed.
+// options is an array of label strings, count is the number of options.
+B32 ui_dropdown(const char *id, const char **options, S32 count, S32 *selected);