fix(desktop): preserve sends with invalid link previews

Co-authored-by: Taylor Ho <taylorkmho@gmail.com>
Signed-off-by: Taylor Ho <taylorkmho@gmail.com>

desktop/src/features/messages/ui/useComposerLinkPreviews.tsx

@@ -192,6 +192,7 @@ export function useComposerLinkPreviews(content: string) {
             faviconUrl: favicon.url,
             faviconSha256: favicon.sha256,
           });
+          if (!tag) return;
           setReadyTags((current) => ({ ...current, [preview.href]: tag }));
         })
         .catch(() => {})

desktop/src/shared/lib/linkPreviewSnapshot.test.mjs

@@ -70,6 +70,7 @@ test("snapshot tags sanitize control characters and enforce UTF-8 byte limits",
     faviconSha256: "",
   });
 
+  assert.ok(tag);
   for (const value of tag.slice(4, 7)) {
     assert.ok(
       Array.from(value).every((char) => {
@@ -83,6 +84,30 @@ test("snapshot tags sanitize control characters and enforce UTF-8 byte limits",
   assert.ok(Buffer.byteLength(tag[6], "utf8") <= 1000);
 });
 
+test("snapshot tags omit canonical URLs rejected by native validation", () => {
+  for (const canonicalUrl of [
+    `${URL}#`,
+    `${URL}#details`,
+    `http://linear.app/acme/issue/ABC-123/example`,
+    `https://user@linear.app/acme/issue/ABC-123/example`,
+  ]) {
+    assert.equal(
+      buildLinkPreviewSnapshotTag({
+        canonicalUrl,
+        title: "Example",
+        siteName: "Linear",
+        description: "Description",
+        imageUrl: "",
+        imageSha256: "",
+        faviconUrl: "",
+        faviconSha256: "",
+      }),
+      null,
+      canonicalUrl,
+    );
+  }
+});
+
 test("messages without authored snapshots never create recipient previews", () => {
   assert.deepEqual(parseLinkPreviewSnapshots([], CONTENT, ORIGIN), []);
   assert.deepEqual(parseLinkPreviewSnapshots(undefined, CONTENT, ORIGIN), []);

desktop/src/shared/lib/linkPreviewSnapshot.ts

@@ -9,6 +9,18 @@ const MAX_SNAPSHOTS = 8;
 const SHA256_RE = /^[0-9a-f]{64}$/;
 const IMAGE_EXT_RE = /^(?:jpg|png|gif|webp)$/;
 
+export function isValidLinkPreviewSnapshotCanonicalUrl(value: string): boolean {
+  if (value.includes("#")) return false;
+  try {
+    const url = new URL(value);
+    return (
+      url.protocol === "https:" && !url.username && !url.password && !url.hash
+    );
+  } catch {
+    return false;
+  }
+}
+
 export type LinkPreviewSnapshot = {
   canonicalUrl: string;
   title: string;
@@ -40,7 +52,7 @@ function sanitizeSnapshotText(value: string, maxBytes: number): string {
 
 function validText(value: string, max: number): boolean {
   return (
-    value.length <= max &&
+    new TextEncoder().encode(value).length <= max &&
     !Array.from(value).some((char) => {
       const code = char.charCodeAt(0);
       return code <= 0x1f || code === 0x7f;
@@ -144,7 +156,9 @@ export function parseLinkPreviewSnapshots(
 
 export function buildLinkPreviewSnapshotTag(
   snapshot: LinkPreviewSnapshot,
-): string[] {
+): string[] | null {
+  if (!isValidLinkPreviewSnapshotCanonicalUrl(snapshot.canonicalUrl))
+    return null;
   return [
     "link-preview",
     "snapshot",

desktop/src/testing/e2eBridge.ts

@@ -62,6 +62,10 @@ import type {
   RuntimeFileConfigSubset,
 } from "@/shared/api/tauri";
 import { normalizePubkey } from "@/shared/lib/pubkey";
+import {
+  isValidLinkPreviewSnapshotCanonicalUrl,
+  parseLinkPreviewSnapshots,
+} from "@/shared/lib/linkPreviewSnapshot";
 
 type TestIdentity = {
   privateKey: string;
@@ -8976,6 +8980,31 @@ async function handleSendChannelMessage(
   // real command and echoed on the stored event. Preserve them in the mock so
   // E2E recipient rendering exercises the same authored-snapshot path.
   const linkPreviewTags = args.linkPreviewTags ?? [];
+  if (linkPreviewTags.length > 0) {
+    const suppression = linkPreviewTags.some(
+      (tag) =>
+        tag.length === 2 && tag[0] === "link-preview" && tag[1] === "none",
+    );
+    const snapshots = linkPreviewTags.filter(
+      (tag) => tag[0] === "link-preview" && tag[1] === "snapshot",
+    );
+    const validSnapshots = parseLinkPreviewSnapshots(
+      snapshots,
+      args.content,
+      new URL(getRelayHttpUrl(config)).origin,
+    );
+    if (
+      (suppression && linkPreviewTags.length !== 1) ||
+      (!suppression &&
+        (snapshots.length !== linkPreviewTags.length ||
+          validSnapshots.length !== snapshots.length ||
+          snapshots.some(
+            (tag) => !isValidLinkPreviewSnapshotCanonicalUrl(tag[3] ?? ""),
+          )))
+    ) {
+      throw new Error("invalid link-preview snapshot tag");
+    }
+  }
   // Both kinds end up on the stored event's tag set, just like the real relay.
   const extraTags = [
     ...mediaTags,

desktop/tests/e2e/messaging.spec.ts

@@ -532,14 +532,31 @@ for (const [pasteShape, wrapUrl] of [
   });
 }
 
-test("completed link preview sends once and leaves the composer cleared", async ({
+test("completed link previews send when one URL has an unsnapshotable fragment", async ({
   page,
 }) => {
-  const previewUrl = "https://github.com/block/buzz/pull/3246?send=complete";
+  const previewUrls = [
+    "https://twitter.com/tellaho",
+    "https://github.com/block/buzz/pull/3246",
+    "https://x.com/tellaho/status/1884289176381841506#",
+  ];
+  const pastedText = previewUrls.join("\n");
   await page.goto("/");
   await page.getByTestId("channel-general").click();
-  await page.getByTestId("message-input").fill(previewUrl);
-  await waitForReadyComposerSnapshots(page);
+  const input = page.getByTestId("message-input");
+  await input.focus();
+  await input.evaluate((element, text) => {
+    const clipboardData = new DataTransfer();
+    clipboardData.setData("text/plain", text);
+    element.dispatchEvent(
+      new ClipboardEvent("paste", {
+        bubbles: true,
+        cancelable: true,
+        clipboardData,
+      }),
+    );
+  }, pastedText);
+  await waitForReadyComposerSnapshots(page, 2);
 
   const send = page.getByTestId("send-message");
   await expect(send).toBeEnabled();
@@ -558,8 +575,8 @@ test("completed link preview sends once and leaves the composer cleared", async
   expect(
     (
       calls[0]?.payload as { linkPreviewTags?: string[][] | null } | undefined
-    )?.linkPreviewTags?.[0]?.slice(0, 4),
-  ).toEqual(["link-preview", "snapshot", "1", previewUrl]);
+    )?.linkPreviewTags?.map((tag) => tag[3]),
+  ).toEqual(previewUrls.slice(0, 2));
 });
 
 test("send does not wait for a pending link preview snapshot", async ({