fix(extension): import the best-quality Twitter video variant

apps/browser-extension/utils/twitter-utils.ts

@@ -56,13 +56,45 @@ interface MediaEntity {
 		}
 	}
 	video_info?: {
-		variants?: Array<{
-			url: string
-		}>
+		variants?: VideoVariant[]
 		duration_millis?: number
 	}
 }
 
+export interface VideoVariant {
+	url: string
+	bitrate?: number
+	content_type?: string
+}
+
+/**
+ * Twitter returns several video variants for a single video: an HLS `.m3u8`
+ * playlist (no bitrate) plus multiple `video/mp4` renditions at different
+ * bitrates, in no guaranteed order. Taking `variants[0]` therefore often stored
+ * the HLS playlist URL (not a directly usable file) or the lowest-quality clip.
+ * Pick the highest-bitrate MP4 instead, falling back to the first variant when
+ * no MP4 rendition is present.
+ */
+export function pickBestVideoVariantUrl(
+	variants: VideoVariant[] | undefined,
+): string {
+	if (!variants || variants.length === 0) return ""
+
+	const mp4s = variants.filter(
+		(v) => v.content_type === "video/mp4" || /\.mp4(?:\?|$)/i.test(v.url),
+	)
+	const pool = mp4s.length > 0 ? mp4s : variants
+
+	let best = pool[0]
+	for (const variant of pool) {
+		if ((variant.bitrate ?? 0) > (best?.bitrate ?? 0)) {
+			best = variant
+		}
+	}
+
+	return best?.url || ""
+}
+
 export interface Tweet {
 	__typename?: string
 	lang?: string
@@ -257,7 +289,7 @@ export function transformTweetData(
 		const videos = media
 			.filter((m) => m.type === "video")
 			.map((m) => ({
-				url: m.video_info?.variants?.[0]?.url || "",
+				url: pickBestVideoVariantUrl(m.video_info?.variants),
 				thumbnail_url: m.media_url_https,
 				duration: m.video_info?.duration_millis || 0,
 			}))

apps/browser-extension/utils/twitter-video-variant.test.ts

@@ -0,0 +1,75 @@
+import { describe, expect, it } from "bun:test"
+import { pickBestVideoVariantUrl } from "./twitter-utils"
+
+describe("pickBestVideoVariantUrl", () => {
+	it("returns an empty string when there are no variants", () => {
+		expect(pickBestVideoVariantUrl(undefined)).toBe("")
+		expect(pickBestVideoVariantUrl([])).toBe("")
+	})
+
+	it("picks the highest-bitrate mp4, not the first variant", () => {
+		const variants = [
+			{
+				url: "https://video.twimg.com/playlist.m3u8",
+				content_type: "application/x-mpegURL",
+			},
+			{
+				url: "https://video.twimg.com/low.mp4",
+				content_type: "video/mp4",
+				bitrate: 256000,
+			},
+			{
+				url: "https://video.twimg.com/high.mp4",
+				content_type: "video/mp4",
+				bitrate: 2176000,
+			},
+			{
+				url: "https://video.twimg.com/mid.mp4",
+				content_type: "video/mp4",
+				bitrate: 832000,
+			},
+		]
+		expect(pickBestVideoVariantUrl(variants)).toBe(
+			"https://video.twimg.com/high.mp4",
+		)
+	})
+
+	it("does not return the HLS playlist when mp4 renditions exist", () => {
+		const variants = [
+			{
+				url: "https://video.twimg.com/playlist.m3u8",
+				content_type: "application/x-mpegURL",
+			},
+			{
+				url: "https://video.twimg.com/only.mp4",
+				content_type: "video/mp4",
+				bitrate: 632000,
+			},
+		]
+		expect(pickBestVideoVariantUrl(variants)).toBe(
+			"https://video.twimg.com/only.mp4",
+		)
+	})
+
+	it("falls back to the first variant when no mp4 is present", () => {
+		const variants = [
+			{
+				url: "https://video.twimg.com/playlist.m3u8",
+				content_type: "application/x-mpegURL",
+			},
+		]
+		expect(pickBestVideoVariantUrl(variants)).toBe(
+			"https://video.twimg.com/playlist.m3u8",
+		)
+	})
+
+	it("detects mp4 by extension when content_type is absent", () => {
+		const variants = [
+			{ url: "https://video.twimg.com/240/vid.mp4?tag=12" },
+			{ url: "https://video.twimg.com/720/vid.mp4?tag=12", bitrate: 2176000 },
+		]
+		expect(pickBestVideoVariantUrl(variants)).toBe(
+			"https://video.twimg.com/720/vid.mp4?tag=12",
+		)
+	})
+})