address review comments

src/renderer/core/layout/injectionKeys.ts

@@ -2,10 +2,41 @@ import type { InjectionKey } from 'vue'
 
 import type { Point } from '@/renderer/core/layout/types'
 
+/**
+ * Lightweight, injectable transform state used by layout-aware components.
+ *
+ * Consumers use this interface to convert coordinates between LiteGraph's
+ * canvas space and the DOM's screen space, access the current pan/zoom
+ * (camera), and perform basic viewport culling checks.
+ *
+ * Coordinate mapping:
+ * - screen = (canvas + offset) * scale
+ * - canvas = screen / scale - offset
+ *
+ * The full implementation and additional helpers live in
+ * `useTransformState()`. This interface deliberately exposes only the
+ * minimal surface needed outside that composable.
+ *
+ * @example
+ * const state = inject(TransformStateKey)!
+ * const screen = state.canvasToScreen({ x: 100, y: 50 })
+ */
 interface TransformState {
+  /** Convert a screen-space point (CSS pixels) to canvas space. */
   screenToCanvas: (p: Point) => Point
+  /** Convert a canvas-space point to screen space (CSS pixels). */
   canvasToScreen: (p: Point) => Point
+  /** Current pan/zoom; `x`/`y` are offsets, `z` is scale. */
   camera?: { x: number; y: number; z: number }
+  /**
+   * Test whether a node's rectangle intersects the (expanded) viewport.
+   * Handy for viewport culling and lazy work.
+   *
+   * @param nodePos Top-left in canvas space `[x, y]`
+   * @param nodeSize Size in canvas units `[width, height]`
+   * @param viewport Screen-space viewport `{ width, height }`
+   * @param margin Optional fractional margin (e.g. `0.2` = 20%)
+   */
   isNodeInViewport?: (
     nodePos: ArrayLike<number>,
     nodeSize: ArrayLike<number>,