diff --git a/src/pixi-augmentations.d.ts b/src/pixi-augmentations.d.ts
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+++ b/src/pixi-augmentations.d.ts
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+import 'pixi.js';
+
+/**
+ * `ExtendedSprite` caches a texture's alpha channel on the texture source itself,
+ * so a pixel-perfect hit test does not have to re-read the pixels on every mouse
+ * move: `hitMap` holds the bytes, `hitMapDirty` says they need regenerating, and
+ * `hitMapTime` throttles how often that happens. `GraphicAssetPalette` fills the
+ * same fields when it bakes a recoloured texture, and `TexturePool` deletes them
+ * when it recycles or destroys one.
+ *
+ * None of the three belongs to PixiJS, so every one of those reads and writes
+ * used to sit behind a `@ts-ignore`. That silences the whole line rather than the
+ * one unknown property, which is why they were removed - declaring the fields
+ * here does the same job without hiding anything else on those lines.
+ *
+ * All three are optional because `TexturePool` `delete`s them and `ExtendedSprite`
+ * reads `hitMapTime` through `?? 0`.
+ *
+ * This file must stay a module - it imports 'pixi.js' for exactly that reason.
+ * In a global script `declare module 'pixi.js'` would declare an ambient module
+ * and shadow the real types instead of adding to them. The type parameter list
+ * has to match the class declaration exactly, or the merge is rejected.
+ */
+declare module 'pixi.js'
+{
+    interface TextureSource<T extends Record<string, any> = any>
+    {
+        hitMap?: Uint8Array | Uint8ClampedArray;
+        hitMapDirty?: boolean;
+        hitMapTime?: number;
+    }
+}