fix(vscode): insert embed flag before any url fragment

packages/op-vscode/src/vscode/webview-shell.test.ts

@@ -69,4 +69,10 @@ describe("appendEmbedQuery", () => {
   test("never percent-encodes the equals sign", () => {
     expect(appendEmbedQuery("http://127.0.0.1:1/")).not.toContain("%3D");
   });
+  test("inserts before a fragment so location.search still sees the flag", () => {
+    expect(appendEmbedQuery("http://127.0.0.1:1/#frag")).toBe("http://127.0.0.1:1/?embed=vscode#frag");
+    expect(appendEmbedQuery("https://t.example/x?tkn=a#frag")).toBe(
+      "https://t.example/x?tkn=a&embed=vscode#frag",
+    );
+  });
 });

packages/op-vscode/src/vscode/webview-shell.ts

@@ -17,7 +17,12 @@ export function originOf(url: string): string {
  *  `EmbedHost::from_query` refuses by design. Tolerates a base that already
  *  carries a query (e.g. tunnel tokens in remote scenarios). */
 export function appendEmbedQuery(base: string): string {
-  return `${base}${base.includes("?") ? "&" : "?"}embed=vscode`;
+  // Insert BEFORE any fragment — a plain tail-append after "#…" would land
+  // the flag inside the fragment, where location.search never sees it.
+  const hashAt = base.indexOf("#");
+  const head = hashAt === -1 ? base : base.slice(0, hashAt);
+  const fragment = hashAt === -1 ? "" : base.slice(hashAt);
+  return `${head}${head.includes("?") ? "&" : "?"}embed=vscode${fragment}`;
 }
 
 /** Phase 1: no iframe. On load it reports window.origin so the extension can