Rebuild UI as a scriptable element tree, archive the old system

The old UI system (X-macro static element list, hand-authored C
screens/widgets/focus stack) is archived under archive/ rather than
deleted, since it's a useful reference during the rewrite.

New native UI element pool (src/dusk/ui): a flat UI_ELEMENTS[128] pool
of tagged-union elements (Label, Rectangle, Scripted), a real
persistent parent/child tree (children[8] per element, cycle- and
capacity-checked uiElementSetParent), always-fresh worldX/worldY
(cheap enough to recompute on every read, no dirty-flag cache needed),
and cascading dispose. Rendering stays manual/immediate: a scripted
element with no render() override auto-renders its children by
default, but overriding render() takes full control (an override must
call renderChildren() itself to opt back in) -- this is deliberately
preserved end to end via a render()-shadow trampoline so overriding
render() always keeps working the same way regardless of how a node
is reached.

New scripting layer (src/dusk/script/module/ui): UIElement/Label/
Rectangle JS classes (Label/Rectangle share UIElement's prototype via
manual chaining, not JS `extends`), exposing x/y/worldX/worldY/parent/
add()/remove()/render()/renderChildren()/dispose(). UI.add()/
UI.remove() manage top-level render roots, mutually exclusive with
being someone's child.

Also: Scene gains a lateUpdate() hook (called once per frame after
every other update, for things like camera-follow that need to react
to where everything else ended up); several duskrpg call sites
(cutscene items, entityinteractable, entityplayer) that depended on
the now-archived RPG textbox are stubbed to console output instead of
a dialogue box, pending the new UI reaching that far.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

archive/duskrpg/ui/textbox/CMakeLists.txt

@@ -0,0 +1,10 @@
+# Copyright (c) 2026 Dominic Masters
+#
+# This software is released under the MIT License.
+# https://opensource.org/licenses/MIT
+
+target_sources(${DUSK_LIBRARY_TARGET_NAME}
+  PUBLIC
+    uitextbox.c
+    uitextboxmain.c
+)

archive/duskrpg/ui/textbox/uitextbox.c

@@ -0,0 +1,276 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#include "uitextbox.h"
+#include "assert/assert.h"
+#include "util/memory.h"
+#include "util/string.h"
+#include "time/time.h"
+#include "display/text/text.h"
+#include "display/color.h"
+#include "display/spritebatch/spritebatch.h"
+#include "display/shader/shaderunlit.h"
+#include "ui/frame/uiframe.h"
+
+void uiTextboxInit(
+  uitextbox_t *box,
+  char_t *text,
+  const uint32_t maxLength,
+  uitextboxline_t *lines,
+  const uint32_t linesMax
+) {
+  assertNotNull(box, "Textbox cannot be NULL");
+  assertNotNull(text, "Text buffer cannot be NULL");
+  assertTrue(maxLength >= 1, "maxLength must be at least 1");
+  assertNotNull(lines, "Lines buffer cannot be NULL");
+  assertTrue(linesMax >= 1, "linesMax must be at least 1");
+  memoryZero(box, sizeof(uitextbox_t));
+  box->text = text;
+  box->maxLength = maxLength;
+  box->lines = lines;
+  box->linesMax = linesMax;
+  box->glyphsBuiltForPage = -1;
+}
+
+void uiTextboxSetText(uitextbox_t *box, const char_t *text) {
+  assertNotNull(box, "Textbox cannot be NULL");
+  assertNotNull(text, "Text cannot be NULL");
+  stringCopy(box->text, text, box->maxLength);
+  box->currentPage = 0;
+  box->scroll = 0;
+  box->layoutWidth = 0.0f;
+  box->layoutHeight = 0.0f;
+  box->glyphsBuiltForPage = -1;
+}
+
+void uiTextboxBuildLayout(
+  uitextbox_t *box,
+  const float_t width,
+  const float_t height
+) {
+  assertNotNull(box, "Textbox cannot be NULL");
+
+  box->glyphsBuiltForPage = -1;
+  box->layoutWidth = width;
+  box->layoutHeight = height;
+  box->lineCount = 0;
+  box->pageCount = 1;
+
+  float_t fontW = (float_t)FONT_DEFAULT.tileset->tileWidth;
+  float_t fontH = (float_t)FONT_DEFAULT.tileset->tileHeight;
+
+  if(fontW <= 0.0f || fontH <= 0.0f) return;
+
+  box->charsPerLine = (int32_t)(width / fontW);
+  box->linesPerPage = (int32_t)(height / (fontH + UI_TEXTBOX_LINE_SPACING));
+  if(box->linesPerPage > UI_TEXTBOX_LINES_PER_PAGE_MAX) {
+    box->linesPerPage = UI_TEXTBOX_LINES_PER_PAGE_MAX;
+  }
+
+  if(box->charsPerLine <= 0 || box->linesPerPage <= 0) return;
+  if(box->text[0] == '\0') return;
+
+  char_t *src = box->text;
+  int32_t i = 0;
+
+  while(src[i] != '\0' && box->lineCount < (int32_t)box->linesMax) {
+    if(src[i] == '\t') {
+      i++;
+      int32_t rem = box->lineCount % box->linesPerPage;
+      int32_t pad = rem > 0 ? box->linesPerPage - rem : 0;
+      while(pad > 0 && box->lineCount < (int32_t)box->linesMax) {
+        box->lines[box->lineCount].start = i;
+        box->lines[box->lineCount].count = 0;
+        box->lineCount++;
+        pad--;
+      }
+      continue;
+    }
+
+    int32_t lineStart = i;
+    int32_t lineWidth = 0;
+
+    while(src[i] != '\0') {
+      char_t c = src[i];
+
+      if(c == '\n') { i++; break; }
+      if(c == '\t') break;
+
+      if(c == ' ') {
+        int32_t wordLen = 0;
+        int32_t j = i + 1;
+        while(
+          src[j] != ' ' && src[j] != '\n' &&
+          src[j] != '\t' && src[j] != '\0'
+        ) {
+          wordLen++;
+          j++;
+        }
+
+        if(lineWidth > 0 && lineWidth + 1 + wordLen > box->charsPerLine) {
+          i++;
+          break;
+        }
+
+        lineWidth++;
+        i++;
+      } else {
+        if(lineWidth >= box->charsPerLine) break;
+        lineWidth++;
+        i++;
+      }
+    }
+
+    box->lines[box->lineCount].start = lineStart;
+    box->lines[box->lineCount].count = lineWidth;
+    box->lineCount++;
+  }
+
+  if(box->lineCount == 0) {
+    box->pageCount = 1;
+  } else {
+    box->pageCount =
+      (box->lineCount + box->linesPerPage - 1) / box->linesPerPage;
+  }
+}
+
+errorret_t uiTextboxUpdate(uitextbox_t *box) {
+  assertNotNull(box, "Textbox cannot be NULL");
+
+  #ifdef DUSK_TIME_DYNAMIC
+    if(TIME.dynamicUpdate) errorOk();
+  #endif
+
+  if(!uiTextboxPageIsComplete(box)) {
+    box->scroll += UI_TEXTBOX_SCROLL_CHARS_PER_TICK;
+  }
+
+  errorOk();
+}
+
+errorret_t uiTextboxDraw(
+  uitextbox_t *box,
+  const float_t x,
+  const float_t y,
+  const float_t width,
+  const float_t height
+) {
+  assertNotNull(box, "Textbox cannot be NULL");
+
+  float_t startX = (float_t)UI_FRAME_START_X;
+  float_t startY = (float_t)UI_FRAME_START_Y;
+  float_t contentX = x + startX;
+  float_t contentY = y + startY;
+  float_t contentW = width - 2.0f * startX;
+  float_t contentH = height - 2.0f * startY;
+
+  if(contentW != box->layoutWidth || contentH != box->layoutHeight) {
+    uiTextboxBuildLayout(box, contentW, contentH);
+  }
+
+  errorChain(uiFrameDrawCached(&box->frameCache, x, y, width, height));
+
+  if(box->lineCount == 0 || box->text[0] == '\0') errorOk();
+
+  if(box->glyphsBuiltForPage != box->currentPage) {
+    uiTextboxBuildPageGlyphs(box);
+  }
+
+  if(box->glyphCount == 0) errorOk();
+
+  int32_t visibleCount = 0;
+  while(
+    visibleCount < box->glyphCount &&
+    box->glyphs[visibleCount].revealAt <= box->scroll
+  ) visibleCount++;
+
+  if(visibleCount == 0) errorOk();
+
+  spritebatchsprite_t scratch[UI_TEXTBOX_PAGE_GLYPHS_MAX];
+  for(int32_t i = 0; i < visibleCount; i++) {
+    scratch[i] = spriteBatchSpriteTranslate(
+      &box->glyphs[i].sprite, contentX, contentY
+    );
+  }
+
+  shadermaterial_t material = {
+    .unlit = {
+      .color = COLOR_WHITE,
+      .texture = FONT_DEFAULT.texture
+    }
+  };
+  errorChain(spriteBatchBuffer(scratch, visibleCount, &SHADER_UNLIT, material));
+
+  errorOk();
+}
+
+void uiTextboxBuildPageGlyphs(uitextbox_t *box) {
+  assertNotNull(box, "Textbox cannot be NULL");
+
+  box->glyphCount = 0;
+
+  int32_t pageFirst = box->currentPage * box->linesPerPage;
+  int32_t pageLast = pageFirst + box->linesPerPage;
+  if(pageLast > box->lineCount) pageLast = box->lineCount;
+
+  float_t fontW = (float_t)FONT_DEFAULT.tileset->tileWidth;
+  float_t fontH = (float_t)FONT_DEFAULT.tileset->tileHeight;
+
+  int32_t consumed = 0;
+  for(int32_t li = pageFirst; li < pageLast; li++) {
+    uitextboxline_t *line = &box->lines[li];
+    float_t lineY =
+      (float_t)(li - pageFirst) * (fontH + UI_TEXTBOX_LINE_SPACING);
+
+    for(int32_t ci = 0; ci < line->count; ci++) {
+      consumed++;
+      char_t c = box->text[line->start + ci];
+      if(c == ' ') continue;
+
+      assertTrue(
+        box->glyphCount < UI_TEXTBOX_PAGE_GLYPHS_MAX,
+        "Textbox page produces too many glyphs"
+      );
+      uitextboxglyph_t *glyph = &box->glyphs[box->glyphCount++];
+      glyph->sprite = textGetSprite(
+        (vec2){ (float_t)ci * fontW, lineY }, c, &FONT_DEFAULT
+      );
+      glyph->revealAt = consumed;
+    }
+  }
+
+  box->glyphsBuiltForPage = box->currentPage;
+}
+
+int32_t uiTextboxGetPageCharCount(const uitextbox_t *box) {
+  assertNotNull(box, "Textbox cannot be NULL");
+  int32_t first = box->currentPage * box->linesPerPage;
+  int32_t last = first + box->linesPerPage;
+  if(last > box->lineCount) last = box->lineCount;
+  int32_t total = 0;
+  for(int32_t i = first; i < last; i++) {
+    total += box->lines[i].count;
+  }
+  return total;
+}
+
+bool_t uiTextboxPageIsComplete(const uitextbox_t *box) {
+  assertNotNull(box, "Textbox cannot be NULL");
+  return box->scroll >= uiTextboxGetPageCharCount(box);
+}
+
+bool_t uiTextboxHasNextPage(const uitextbox_t *box) {
+  assertNotNull(box, "Textbox cannot be NULL");
+  return box->currentPage + 1 < box->pageCount;
+}
+
+void uiTextboxNextPage(uitextbox_t *box) {
+  assertNotNull(box, "Textbox cannot be NULL");
+  if(!uiTextboxHasNextPage(box)) return;
+  box->currentPage++;
+  box->scroll = 0;
+}

archive/duskrpg/ui/textbox/uitextbox.h

@@ -0,0 +1,175 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#pragma once
+#include "error/error.h"
+#include "ui/frame/uiframe.h"
+#include "display/spritebatch/spritebatchsprite.h"
+
+#define UI_TEXTBOX_LINES_PER_PAGE_MAX 4
+#define UI_TEXTBOX_SCROLL_CHARS_PER_TICK 1
+#define UI_TEXTBOX_LINE_SPACING 0.0f
+
+// Fixed capacity for a page's cached glyph sprites (see uitextboxglyph_t).
+// Sized generously above UI_TEXTBOX_LINES_PER_PAGE_MAX worth of glyphs at
+// typical textbox widths; uiTextboxBuildPageGlyphs asserts if a page
+// somehow produces more than this.
+#define UI_TEXTBOX_PAGE_GLYPHS_MAX 512
+
+typedef struct {
+  int32_t start;
+  int32_t count;
+} uitextboxline_t;
+
+// A single visible glyph's cached sprite (relative to the textbox's
+// content origin, i.e. (0,0)) plus the scroll value at/after which it
+// becomes visible -- lets uiTextboxDraw turn the typewriter scroll into
+// a simple prefix-count instead of recomputing glyph geometry every
+// frame.
+typedef struct {
+  spritebatchsprite_t sprite;
+  int32_t revealAt;
+} uitextboxglyph_t;
+
+typedef struct {
+  char_t *text;
+  uint32_t maxLength;
+
+  uitextboxline_t *lines;
+  uint32_t linesMax;
+  int32_t lineCount;
+  int32_t charsPerLine;
+  int32_t linesPerPage;
+  int32_t pageCount;
+
+  // last dimensions used for layout; rebuild triggers when these change
+  float_t layoutWidth;
+  float_t layoutHeight;
+
+  int32_t currentPage;
+  int32_t scroll;
+
+  // Cached glyph sprites for the current page (see uitextboxglyph_t),
+  // rebuilt only when currentPage no longer matches
+  // glyphsBuiltForPage -- not every frame/scroll tick.
+  uitextboxglyph_t glyphs[UI_TEXTBOX_PAGE_GLYPHS_MAX];
+  int32_t glyphCount;
+  int32_t glyphsBuiltForPage;
+
+  uiframecache_t frameCache;
+} uitextbox_t;
+
+/**
+ * Initializes a textbox, zeroing all state and binding it to caller-owned
+ * text and line storage.
+ *
+ * @param box The textbox to initialize.
+ * @param text Caller-owned buffer the textbox copies its text into.
+ * @param maxLength Capacity of text, in characters.
+ * @param lines Caller-owned buffer the textbox lays lines out into.
+ * @param linesMax Capacity of lines, in entries.
+ */
+void uiTextboxInit(
+  uitextbox_t *box,
+  char_t *text,
+  const uint32_t maxLength,
+  uitextboxline_t *lines,
+  const uint32_t linesMax
+);
+
+/**
+ * Copies text into the textbox and marks layout as dirty.
+ * Resets currentPage and scroll to 0.
+ *
+ * @param box The textbox to update.
+ * @param text Null-terminated source string.
+ */
+void uiTextboxSetText(uitextbox_t *box, const char_t *text);
+
+/**
+ * Rebuilds word-wrap and page layout for the given draw dimensions.
+ * Called automatically by uiTextboxDraw when width or height changes.
+ *
+ * @param box The textbox to rebuild.
+ * @param width Available content width in pixels.
+ * @param height Available content height in pixels.
+ */
+void uiTextboxBuildLayout(
+  uitextbox_t *box,
+  const float_t width,
+  const float_t height
+);
+
+/**
+ * Advances the typewriter scroll by UI_TEXTBOX_SCROLL_CHARS_PER_TICK.
+ * Skipped on dynamic ticks.
+ *
+ * @param box The textbox to update.
+ * @returns Any error that occurs.
+ */
+errorret_t uiTextboxUpdate(uitextbox_t *box);
+
+/**
+ * Draws the textbox frame and visible text. Rebuilds layout automatically
+ * if width or height differs from the last draw call.
+ *
+ * @param box The textbox to draw.
+ * @param x Screen x position.
+ * @param y Screen y position.
+ * @param width Draw width in pixels.
+ * @param height Draw height in pixels.
+ * @returns Any error that occurs.
+ */
+errorret_t uiTextboxDraw(
+  uitextbox_t *box,
+  const float_t x,
+  const float_t y,
+  const float_t width,
+  const float_t height
+);
+
+/**
+ * Returns the total visible char count for the current page.
+ *
+ * @param box The textbox to query.
+ * @returns Total chars on the current page.
+ */
+int32_t uiTextboxGetPageCharCount(const uitextbox_t *box);
+
+/**
+ * Returns true when scroll has fully revealed the current page.
+ *
+ * @param box The textbox to query.
+ * @returns True if the current page is fully visible.
+ */
+bool_t uiTextboxPageIsComplete(const uitextbox_t *box);
+
+/**
+ * Returns true when there is at least one more page after the current one.
+ *
+ * @param box The textbox to query.
+ * @returns True if a next page exists.
+ */
+bool_t uiTextboxHasNextPage(const uitextbox_t *box);
+
+/**
+ * Advances to the next page and resets scroll to 0.
+ * Has no effect if already on the last page.
+ *
+ * @param box The textbox to advance.
+ */
+void uiTextboxNextPage(uitextbox_t *box);
+
+/**
+ * Rebuilds the cached glyph sprites (see uitextboxglyph_t) for the
+ * current page from its line layout. Called automatically by
+ * uiTextboxDraw whenever currentPage no longer matches the page the
+ * cache was last built for.
+ *
+ * @param box The textbox to rebuild.
+ */
+void uiTextboxBuildPageGlyphs(uitextbox_t *box);

archive/duskrpg/ui/textbox/uitextboxmain.c

@@ -0,0 +1,121 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#include "uitextboxmain.h"
+#include "ui/focus/uifocus.h"
+#include "display/screen/screen.h"
+#include "display/text/text.h"
+#include "display/color.h"
+#include "display/spritebatch/spritebatch.h"
+#include "display/shader/shaderunlit.h"
+#include "ui/frame/uiframe.h"
+
+uitextboxmain_t UI_TEXTBOX_MAIN;
+static uifocusitem_t *focusItem = NULL;
+
+errorret_t uiTextboxMainInit(void) {
+  uiTextboxInit(
+    &UI_TEXTBOX_MAIN.box,
+    UI_TEXTBOX_MAIN.text, UI_TEXTBOX_MAIN_TEXT_MAX,
+    UI_TEXTBOX_MAIN.lines, UI_TEXTBOX_MAIN_LINES_MAX
+  );
+  errorOk();
+}
+
+void uiTextboxMainSetText(const char_t *text) {
+  uiTextboxSetText(&UI_TEXTBOX_MAIN.box, text);
+  if(focusItem != NULL) return;
+  focusItem = uiFocusPush(
+    1, 1,
+    uiTextboxMainFocusSelected,
+    NULL,
+    uiTextboxMainFocusClosed,
+    NULL,
+    NULL
+  );
+}
+
+errorret_t uiTextboxMainUpdate(void) {
+  if(focusItem == NULL) errorOk();
+  return uiTextboxUpdate(&UI_TEXTBOX_MAIN.box);
+}
+
+errorret_t uiTextboxMainDraw(void) {
+  if(focusItem == NULL) errorOk();
+  float_t fontH = (float_t)FONT_DEFAULT.tileset->tileHeight;
+  float_t h = (float_t)UI_TEXTBOX_MAIN_LINES * fontH +
+    (float_t)(UI_TEXTBOX_MAIN_LINES - 1) * UI_TEXTBOX_LINE_SPACING +
+    2.0f * (float_t)UI_FRAME_START_Y;
+  float_t w = (float_t)SCREEN.scanWidth;
+  float_t x = (float_t)SCREEN.scanX;
+  float_t y = (float_t)(SCREEN.scanY + SCREEN.scanHeight) - h;
+  errorChain(uiTextboxDraw(&UI_TEXTBOX_MAIN.box, x, y, w, h));
+
+  if(!uiTextboxPageIsComplete(&UI_TEXTBOX_MAIN.box)) errorOk();
+
+  float_t fontW = (float_t)FONT_DEFAULT.tileset->tileWidth;
+  float_t contentX = x + (float_t)UI_FRAME_START_X;
+  float_t contentY = y + (float_t)UI_FRAME_START_Y;
+  float_t contentW = w - 2.0f * (float_t)UI_FRAME_START_X;
+  float_t contentH = h - 2.0f * (float_t)UI_FRAME_START_Y;
+
+  shadermaterial_t material = {
+    .unlit = {
+      .color = COLOR_WHITE,
+      .texture = FONT_DEFAULT.texture
+    }
+  };
+
+  spritebatchsprite_t caret = textGetSprite(
+    (vec2){
+      contentX + contentW - fontW,
+      contentY + contentH - fontH
+    },
+    'v',
+    &FONT_DEFAULT
+  );
+  errorChain(spriteBatchBuffer(&caret, 1, &SHADER_UNLIT, material));
+
+  errorOk();
+}
+
+bool_t uiTextboxMainPageIsComplete(void) {
+  return uiTextboxPageIsComplete(&UI_TEXTBOX_MAIN.box);
+}
+
+bool_t uiTextboxMainHasNextPage(void) {
+  return uiTextboxHasNextPage(&UI_TEXTBOX_MAIN.box);
+}
+
+void uiTextboxMainNextPage(void) {
+  uiTextboxNextPage(&UI_TEXTBOX_MAIN.box);
+}
+
+bool_t uiTextboxMainIsActive(void) {
+  return focusItem != NULL;
+}
+
+bool_t uiTextboxMainFocusSelected(const uifocusitem_t *item) {
+  if(!uiTextboxPageIsComplete(&UI_TEXTBOX_MAIN.box)) {
+    UI_TEXTBOX_MAIN.box.scroll =
+      uiTextboxGetPageCharCount(&UI_TEXTBOX_MAIN.box);
+    return true;
+  }
+
+  if(uiTextboxHasNextPage(&UI_TEXTBOX_MAIN.box)) {
+    uiTextboxNextPage(&UI_TEXTBOX_MAIN.box);
+    return true;
+  }
+
+  uiFocusPopItem(focusItem);
+  return true;
+}
+
+bool_t uiTextboxMainFocusClosed(const uifocusitem_t *item) {
+  focusItem = NULL;
+  return true;
+}

archive/duskrpg/ui/textbox/uitextboxmain.h

@@ -0,0 +1,94 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#pragma once
+#include "uitextbox.h"
+#include "ui/focus/uifocusitem.h"
+
+#define UI_TEXTBOX_MAIN_LINES 4
+#define UI_TEXTBOX_MAIN_TEXT_MAX 1024
+#define UI_TEXTBOX_MAIN_LINES_MAX 64
+
+typedef struct {
+  uitextbox_t box;
+  char_t text[UI_TEXTBOX_MAIN_TEXT_MAX];
+  uitextboxline_t lines[UI_TEXTBOX_MAIN_LINES_MAX];
+} uitextboxmain_t;
+
+extern uitextboxmain_t UI_TEXTBOX_MAIN;
+
+/**
+ * Initializes UI_TEXTBOX_MAIN.
+ *
+ * @returns Any error that occurs.
+ */
+errorret_t uiTextboxMainInit(void);
+
+/**
+ * Copies text into UI_TEXTBOX_MAIN and resets page and scroll.
+ *
+ * @param text Null-terminated source string.
+ */
+void uiTextboxMainSetText(const char_t *text);
+
+/**
+ * Advances the typewriter scroll for UI_TEXTBOX_MAIN.
+ *
+ * @returns Any error that occurs.
+ */
+errorret_t uiTextboxMainUpdate(void);
+
+/**
+ * Draws UI_TEXTBOX_MAIN full-width at the bottom of the screen.
+ * Position and size are derived from SCREEN each call.
+ *
+ * @returns Any error that occurs.
+ */
+errorret_t uiTextboxMainDraw(void);
+
+/**
+ * Returns true when the current page is fully scrolled in.
+ *
+ * @returns True if the current page is complete.
+ */
+bool_t uiTextboxMainPageIsComplete(void);
+
+/**
+ * Returns true when at least one more page follows the current one.
+ *
+ * @returns True if a next page exists.
+ */
+bool_t uiTextboxMainHasNextPage(void);
+
+/**
+ * Advances UI_TEXTBOX_MAIN to the next page and resets scroll.
+ * Has no effect if already on the last page.
+ */
+void uiTextboxMainNextPage(void);
+
+/**
+ * Returns true when UI_TEXTBOX_MAIN has focus (is visible and active).
+ *
+ * @returns True if the textbox is currently active.
+ */
+bool_t uiTextboxMainIsActive(void);
+
+/**
+ * Internal focus callback - skip scroll or advance page or dismiss.
+ *
+ * @param item The active focus item.
+ * @returns True.
+ */
+bool_t uiTextboxMainFocusSelected(const uifocusitem_t *item);
+
+/**
+ * Internal focus callback - clears the focus item pointer on dismiss.
+ *
+ * @param item The focus item being closed.
+ * @returns True.
+ */
+bool_t uiTextboxMainFocusClosed(const uifocusitem_t *item);

archive/duskrpg/ui/uitestlabel.c

@@ -0,0 +1,35 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#include "uitestlabel.h"
+#include "ui/widget/uilabel.h"
+#include "display/text/text.h"
+#include "display/screen/screen.h"
+#include "engine/engine.h"
+
+uilabel_t UI_TEST_LABEL;
+
+errorret_t uiTestLabelInit() {
+  uiLabelInit(&UI_TEST_LABEL, &FONT_DEFAULT);
+  uiLabelSetText(&UI_TEST_LABEL, "duskrpg");
+  errorOk();
+}
+
+errorret_t uiTestLabelDraw() {
+  int32_t versionWidth, versionHeight;
+  textMeasure(ENGINE.version, &FONT_DEFAULT, &versionWidth, &versionHeight);
+
+  errorChain(uiLabelDraw(
+    &UI_TEST_LABEL,
+    (float_t)(SCREEN.scanX + SCREEN.scanWidth - UI_TEST_LABEL.width),
+    (float_t)(
+      SCREEN.scanY + SCREEN.scanHeight - versionHeight -
+      UI_TEST_LABEL.height
+    )
+  ));
+  errorOk();
+}

archive/duskrpg/ui/uitestlabel.h

@@ -0,0 +1,24 @@
+/**
+ * Copyright (c) 2026 Dominic Masters
+ *
+ * This software is released under the MIT License.
+ * https://opensource.org/licenses/MIT
+ */
+
+#pragma once
+#include "error/error.h"
+
+/**
+ * Initializes the test label, a smoke test for the duskrpg-side UI
+ * element extension point (uielementgame.h).
+ *
+ * @return Any error that occurs.
+ */
+errorret_t uiTestLabelInit();
+
+/**
+ * Draws the test label above the engine's debug version number.
+ *
+ * @return Any error that occurs.
+ */
+errorret_t uiTestLabelDraw();