refactor: rename RowWaveform to BackgroundWaveform, drop wrapper div

Rename to BackgroundWaveform to reflect its visual role rather than
structural placement. Remove the redundant wrapper div — Row already
provides relative overflow-hidden, so the canvas can sit absolute
inset-0 directly and observe itself via ResizeObserver.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/components/video-editor/timeline/BackgroundWaveform.tsx

@@ -1,39 +1,40 @@
 import { useTimelineContext } from "dnd-timeline";
 import { useEffect, useRef, useState } from "react";
 
-export interface RowWaveformProps {
+export interface BackgroundWaveformProps {
 	/** Pre-computed peaks array: pairs of [min, max] per block (length = 2 * N). */
 	peaks: Float32Array | null;
 	videoDurationMs: number;
 }
 
 /**
- * Renders a faint audio waveform on a `<canvas>` element that fills its
- * containing row. Designed to be passed as the `background` prop of `<Row>`.
+ * Renders a faint audio waveform on a `<canvas>` that fills its containing
+ * block. Designed to be passed as the `background` prop of `<Row>`, which
+ * already provides `relative overflow-hidden` — no wrapper element needed.
  *
  * - Accepts pre-computed `peaks` from the caller (see `useAudioPeaks`).
  * - Redraws whenever the timeline zoom/pan range changes.
- * - `pointer-events: none` throughout — never blocks drag-to-create interactions.
+ * - `pointer-events: none` — never blocks drag-to-create interactions.
  */
-export default function RowWaveform({ peaks, videoDurationMs }: RowWaveformProps) {
+export default function BackgroundWaveform({ peaks, videoDurationMs }: BackgroundWaveformProps) {
 	const { range } = useTimelineContext();
 	const canvasRef = useRef<HTMLCanvasElement>(null);
-	const wrapperRef = useRef<HTMLDivElement>(null);
 	const [canvasSize, setCanvasSize] = useState({ w: 0, h: 0 });
 
-	// Track container dimensions via ResizeObserver.
+	// Observe the canvas itself — Row's `relative overflow-hidden` parent
+	// makes it fill the row exactly, so no wrapper div is needed.
 	useEffect(() => {
-		const el = wrapperRef.current;
-		if (!el) return;
+		const canvas = canvasRef.current;
+		if (!canvas) return;
 		const ro = new ResizeObserver((entries) => {
 			const { width, height } = entries[0].contentRect;
 			setCanvasSize({ w: width, h: height });
 		});
-		ro.observe(el);
+		ro.observe(canvas);
 		return () => ro.disconnect();
 	}, []);
 
-	// Redraw whenever peaks, range, or container size changes.
+	// Redraw whenever peaks, range, or canvas size changes.
 	useEffect(() => {
 		const canvas = canvasRef.current;
 		if (!canvas || !peaks || canvasSize.w <= 0 || canvasSize.h <= 0) return;
@@ -83,12 +84,5 @@ export default function RowWaveform({ peaks, videoDurationMs }: RowWaveformProps
 		ctx.stroke();
 	}, [peaks, range, canvasSize, videoDurationMs]);
 
-	return (
-		<div ref={wrapperRef} className="absolute inset-0 pointer-events-none overflow-hidden">
-			<canvas
-				ref={canvasRef}
-				style={{ width: canvasSize.w, height: canvasSize.h, display: "block" }}
-			/>
-		</div>
-	);
+	return <canvas ref={canvasRef} className="absolute inset-0 pointer-events-none w-full h-full" />;
 }

src/components/video-editor/timeline/TimelineEditor.tsx

@@ -35,10 +35,10 @@ import type {
 	ZoomFocus,
 	ZoomRegion,
 } from "../types";
+import BackgroundWaveform from "./BackgroundWaveform";
 import Item from "./Item";
 import KeyframeMarkers from "./KeyframeMarkers";
 import Row from "./Row";
-import RowWaveform from "./RowWaveform";
 import TimelineWrapper from "./TimelineWrapper";
 import { detectZoomDwellCandidates, normalizeCursorTelemetry } from "./zoomSuggestionUtils";
 
@@ -803,7 +803,7 @@ function Timeline({
 				hint={t("hints.pressTrim")}
 				background={
 					showTrimWaveform ? (
-						<RowWaveform peaks={peaks} videoDurationMs={videoDurationMs} />
+						<BackgroundWaveform peaks={peaks} videoDurationMs={videoDurationMs} />
 					) : undefined
 				}
 			>