From c731d5b1f50745c93109832972bd59f9b4a5fb09 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E5=8D=93=E6=A9=A6?=
 <107380090+dangzhuotong@users.noreply.github.com>
Date: Wed, 14 Oct 2026 11:52:57 +0000
Subject: [PATCH] fix: accept the configured web host in share URL parsing
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Self-hosted Slack unfurls and /api/oembed dropped /s/<id> links because
parseCapShareUrl only allowed cap.so and cap.link.

Fixes #2546

Co-authored-by: 卓橦 <dangzhuotong@users.noreply.github.com>
---
 apps/web/__tests__/unit/oembed.test.ts | 26 +++++++++++++++++++++++++-
 apps/web/lib/oembed.ts                 | 18 +++++++++++++++++-
 apps/web/lib/share-video-metadata.ts   |  4 ++--
 3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/apps/web/__tests__/unit/oembed.test.ts b/apps/web/__tests__/unit/oembed.test.ts
index eba9f7021f2..b9d0b3a82f8 100644
--- a/apps/web/__tests__/unit/oembed.test.ts
+++ b/apps/web/__tests__/unit/oembed.test.ts
@@ -1,8 +1,16 @@
 import { Video } from "@cap/web-domain";
-import { describe, expect, it } from "vitest";
+import { describe, expect, it, vi } from "vitest";
 import { buildOEmbedVideo, parseCapShareUrl } from "@/lib/oembed";
 import type { PublicShareVideo } from "@/lib/public-share-video";
 
+const serverEnvMock = vi.hoisted(() =>
+	vi.fn(() => ({ WEB_URL: "https://www.video.example.com" })),
+);
+
+vi.mock("@cap/env", () => ({
+	serverEnv: serverEnvMock,
+}));
+
 const video: PublicShareVideo = {
 	id: Video.VideoId.make("abc123"),
 	name: "Cap walkthrough",
@@ -20,13 +28,19 @@ describe("Cap oEmbed", () => {
 		["https://www.cap.so/s/abc123?t=3", "abc123"],
 		["https://cap.link/abc123", "abc123"],
 		["https://www.cap.link/abc123?foo=bar", "abc123"],
+		["https://video.example.com/s/abc123", "abc123"],
+		["https://www.video.example.com/s/abc123?t=3", "abc123"],
 	])("parses supported share URL %s", (url, expected) => {
 		expect(parseCapShareUrl(url)).toBe(expected);
 	});
 
 	it.each([
 		"http://cap.so/s/abc123",
+		"http://video.example.com/s/abc123",
 		"https://example.com/s/abc123",
+		"https://video.example.com/abc123",
+		"https://video.example.com/embed/abc123",
+		"https://cap.link/s/abc123",
 		"https://cap.so/embed/abc123",
 		"https://cap.link/video/demo.mp4",
 		"https://cap.so/s/abc123/extra",
@@ -35,6 +49,16 @@ describe("Cap oEmbed", () => {
 		expect(parseCapShareUrl(url)).toBeNull();
 	});
 
+	it("ignores an unreadable WEB_URL instead of failing the parse", () => {
+		serverEnvMock.mockImplementationOnce(() => {
+			throw new Error("Invalid environment variables");
+		});
+
+		expect(parseCapShareUrl("https://video.example.com/s/abc123")).toBeNull();
+		expect(parseCapShareUrl("https://cap.so/s/abc123")).toBe("abc123");
+		expect(parseCapShareUrl("https://cap.link/abc123")).toBe("abc123");
+	});
+
 	it("returns a responsive video response with preserved dimensions", () => {
 		const result = buildOEmbedVideo({
 			video,
diff --git a/apps/web/lib/oembed.ts b/apps/web/lib/oembed.ts
index d6d72965a2b..ca0b3a0f459 100644
--- a/apps/web/lib/oembed.ts
+++ b/apps/web/lib/oembed.ts
@@ -1,3 +1,4 @@
+import { serverEnv } from "@cap/env";
 import type { PublicShareVideo } from "@/lib/public-share-video";
 
 const DEFAULT_WIDTH = 800;
@@ -49,6 +50,17 @@ const scaleDimensions = ({
 	};
 };
 
+const configuredShareHost = () => {
+	try {
+		return new URL(serverEnv().WEB_URL).hostname
+			.toLowerCase()
+			.replace(/^www\./, "");
+	} catch {
+		// A missing or invalid WEB_URL must not reject cap.so / cap.link links.
+		return undefined;
+	}
+};
+
 export const parseCapShareUrl = (value: string) => {
 	let url: URL;
 	try {
@@ -62,7 +74,11 @@ export const parseCapShareUrl = (value: string) => {
 	const segments = url.pathname.split("/").filter(Boolean);
 	let videoId: string | undefined;
 
-	if (hostname === "cap.so" && segments.length === 2 && segments[0] === "s") {
+	if (
+		segments.length === 2 &&
+		segments[0] === "s" &&
+		(hostname === "cap.so" || hostname === configuredShareHost())
+	) {
 		videoId = segments[1];
 	}
 	if (
diff --git a/apps/web/lib/share-video-metadata.ts b/apps/web/lib/share-video-metadata.ts
index fe832eb2155..769055e0a85 100644
--- a/apps/web/lib/share-video-metadata.ts
+++ b/apps/web/lib/share-video-metadata.ts
@@ -18,8 +18,8 @@ export type ShareVideoMetadataInput = {
 	/**
 	 * Two surfaces only answer on the default Cap origin: `proxy.ts` redirects
 	 * `/embed/` away from a custom domain, and `parseCapShareUrl` accepts share
-	 * URLs on `cap.so` and `cap.link` alone, so `/api/oembed` rejects a custom
-	 * domain `url`. Defaults to `webUrl`.
+	 * URLs on `cap.so`, `cap.link`, and the configured `WEB_URL` host, so
+	 * `/api/oembed` rejects a different custom-domain `url`. Defaults to `webUrl`.
 	 */
 	canonicalWebUrl?: string;
 	advertiseIframelyPlayer?: boolean;