src/entities/Font/lib/dualFontLayout/DualFontLayout/DualFontLayout.ts

@@ -9,43 +9,6 @@ import {
  */
 const DEFAULT_RENDER_SIZE_PX = 16;
 
-/**
- * Internal shape of pretext's PreparedTextWithSegments — only `segments` is in
- * pretext's public TS type; the numeric arrays exist at runtime but are not in
- * the published signature. Verified against node_modules/@chenglou/pretext/src/layout.ts.
- */
-interface PretextInternals {
-    /**
-     * Per-segment text.
-     */
-    segments: string[];
-    /**
-     * Per-segment full width in pixels.
-     */
-    widths: number[];
-    /**
-     * Per-segment per-grapheme advance widths, or null when the segment is a single grapheme.
-     */
-    breakableFitAdvances: (number[] | null)[];
-    /**
-     * Per-segment line-end fit advance.
-     */
-    lineEndFitAdvances: number[];
-    /**
-     * Per-segment line-end paint advance.
-     */
-    lineEndPaintAdvances: number[];
-}
-
-/**
- * Asserts pretext's runtime shape. The public TS type exposes only `segments`;
- * the numeric arrays exist at runtime but are absent from the published signature.
- * Centralizing the cast keeps the engine body free of `as any`.
- */
-function asPretextInternals(prepared: PreparedTextWithSegments): PretextInternals {
-    return prepared as unknown as PretextInternals;
-}
-
 /**
  * Per-grapheme data computed during dual-font layout. Internal to the engine;
  * consumed by computeLineRenderModel to derive the per-frame render model.
@@ -114,6 +77,10 @@ export interface ComparisonResult {
  * of font A and font B. This guarantees that both fonts wrap at exactly the same
  * positions, making side-by-side or slider comparison visually coherent.
  *
+ * Relies on pretext's published structural fields on `PreparedTextWithSegments`
+ * (`widths`, `breakableFitAdvances`, `lineEndFitAdvances`, `lineEndPaintAdvances`)
+ * which are exposed via the `PreparedCore` intersection in `@chenglou/pretext@0.0.6`.
+ *
  * **Two-level caching strategy**
  * 1. Font-change cache (`#preparedA`, `#preparedB`, `#unifiedPrepared`): rebuilt only
  *    when `text`, `fontA`, or `fontB` changes. `prepareWithSegments` is expensive
@@ -129,9 +96,9 @@ export class DualFontLayout {
     #segmenter: Intl.Segmenter;
 
     // Cached prepared data
-    #preparedA: PretextInternals | null = null;
+    #preparedA: PreparedTextWithSegments | null = null;
-    #preparedB: PretextInternals | null = null;
+    #preparedB: PreparedTextWithSegments | null = null;
-    #unifiedPrepared: PretextInternals | null = null;
+    #unifiedPrepared: PreparedTextWithSegments | null = null;
 
     #lastText = '';
     #lastFontA = '';
@@ -192,8 +159,8 @@ export class DualFontLayout {
 
         // 1. Prepare (or use cache)
         if (isFontChange) {
-            this.#preparedA = asPretextInternals(prepareWithSegments(text, fontA));
+            this.#preparedA = prepareWithSegments(text, fontA);
-            this.#preparedB = asPretextInternals(prepareWithSegments(text, fontB));
+            this.#preparedB = prepareWithSegments(text, fontB);
             this.#unifiedPrepared = this.#createUnifiedPrepared(this.#preparedA, this.#preparedB, spacingPx);
 
             this.#lastText = text;
@@ -207,13 +174,7 @@ export class DualFontLayout {
             return { lines: [], totalHeight: 0 };
         }
 
-        // pretext's `layoutWithLines` is typed against its public surface; pass the
+        const { lines, height } = layoutWithLines(this.#unifiedPrepared, width, lineHeight);
-        // runtime-internal shape through with one boundary cast.
-        const { lines, height } = layoutWithLines(
-            this.#unifiedPrepared as unknown as PreparedTextWithSegments,
-            width,
-            lineHeight,
-        );
 
         // 3. Map results back to both fonts
         const preparedA = this.#preparedA;
@@ -284,11 +245,11 @@ export class DualFontLayout {
      * across both fonts, with `spacingPx` added to model letter-spacing.
      */
     #createUnifiedPrepared(
-        a: PretextInternals,
+        a: PreparedTextWithSegments,
-        b: PretextInternals,
+        b: PreparedTextWithSegments,
         spacingPx: number = 0,
-    ): PretextInternals {
+    ): PreparedTextWithSegments {
-        const unified: PretextInternals = { ...a };
+        const unified: PreparedTextWithSegments = { ...a };
 
         unified.widths = a.widths.map((w, i) => Math.max(w, b.widths[i]) + spacingPx);
         unified.lineEndFitAdvances = a.lineEndFitAdvances.map((w, i) =>