feat(theseus/chrome): "Open link in new window" on the link context menu

A standalone page window on the same session (cookies, bns:// protocol,
session-wide bcnr preload) with Theseus's fingerprint + WebRTC policy and
no toolbar. Loads BCNR-first like a tab: a dotted host with a BCNR record
goes over bns://, otherwise clearnet; collision names follow the configured
policy without the "Open with…" interstitial. Cross-host navigations inside
the window stay BCNR-first; popups go to the main window's tabs. Its own
context menu offers open-in-tab / open-in-window / copy link and
back/forward/reload. Add-on page bridges (wallet inject) are tab-scoped and
don't run in these windows. openLinkWindow is exported for the test harness.

Verified in the dev app: coinspectrum.x opened as bns://coinspectrum.x with
the page title; navigate.st stayed https.

main.js

@@ -2686,6 +2686,7 @@ function createTab(initial, opts = {}) {
       items.push(
         { label: "Open link in new tab", click: () => createTab(p.linkURL) },
         { label: "Open link in new background tab", click: () => createTab(p.linkURL, { background: true }) },
+        { label: "Open link in new window", click: () => openLinkWindow(p.linkURL) },
         { label: "Copy link address", click: () => clipboard.writeText(p.linkURL) },
         { type: "separator" },
       );
@@ -4760,6 +4761,91 @@ ipcMain.handle("hermes-send", async (_e, { to, text } = {}) => {
   } catch (e) { return hErr(e); }
 });
 
+// ---- "Open link in new window" ----
+// A standalone page window: same session (cookies, the bns:// protocol, the
+// session-wide bcnr preload), Theseus's fingerprint + WebRTC policy, no
+// toolbar. Loads BCNR-first like a tab does: a dotted host with a BCNR
+// record goes over bns://, anything else over clearnet. Collision names
+// follow the configured policy without the "Open with…" interstitial.
+// Add-on page bridges (the wallet inject) are tab-scoped and don't run here.
+const linkWindows = new Set();
+async function targetUrlFor(input) {
+  let u;
+  try { u = new URL(String(input).includes("://") ? String(input) : "https://" + String(input)); } catch { return null; }
+  if (u.protocol !== "http:" && u.protocol !== "https:") return u.href;
+  const host = u.hostname.toLowerCase();
+  if (!isBnsHost(host)) return u.href;
+  let entry = null;
+  try { entry = await resolveHost(host); } catch {}
+  if (!entry) return u.href;
+  const policy = settings.collisionPolicy || "bcnr-first";
+  if (!isBcnrNativeTld(tldOf(host)) && policy === "icann-first") return u.href;
+  return `bns://${host}${u.pathname}${u.search}${u.hash}`;
+}
+async function openLinkWindow(input) {
+  const target = await targetUrlFor(input);
+  if (!target) return null;
+  const w = new BrowserWindow({
+    width: 1100, height: 760, title: "Theseus Navigator",
+    backgroundColor: nativeTheme.shouldUseDarkColors ? "#0b0e14" : "#ffffff",
+    icon: app.isPackaged ? path.join(process.resourcesPath, "icon.ico") : path.join(__dirname, "build", "icon.ico"),
+    webPreferences: { contextIsolation: true, nodeIntegration: false, sandbox: true },
+  });
+  w.setMenuBarVisibility(false);
+  const wc = w.webContents;
+  styleScrollbars(wc);
+  try { wc.setWebRTCIPHandlingPolicy(webrtcPolicy()); } catch {}
+  try { wc.setBackgroundThrottling(settings.backgroundThrottle); } catch {}
+  applyFingerprint(wc);
+  wc.on("page-title-updated", (_e, title) => { try { w.setTitle(title ? `${title} — Theseus` : "Theseus Navigator"); } catch {} });
+  // Cross-host navigations inside the window stay BCNR-first too. Same-host
+  // ones go through Chromium untouched (form POSTs must survive).
+  wc.on("will-navigate", (e, u) => {
+    try {
+      const p = new URL(u);
+      if (p.protocol !== "http:" && p.protocol !== "https:") return;
+      if (!isBnsHost(p.hostname)) return;
+      let cur = ""; try { cur = new URL(wc.getURL()).hostname; } catch {}
+      if (cur === p.hostname) return;
+      e.preventDefault();
+      targetUrlFor(u).then((t) => { if (t) wc.loadURL(t).catch(() => {}); });
+    } catch {}
+  });
+  // Popups from a page here go to the main window's tabs when it exists —
+  // one place for tabs — otherwise to another plain window.
+  wc.setWindowOpenHandler(({ url }) => {
+    if (url && url !== "about:blank") {
+      if (win && !win.isDestroyed()) { createTab(url); try { win.focus(); } catch {} }
+      else openLinkWindow(url);
+    }
+    return { action: "deny" };
+  });
+  wc.on("context-menu", (_e, p) => {
+    const items = [];
+    const haveMain = !!win && !win.isDestroyed();
+    if (p.linkURL) {
+      items.push(
+        { label: "Open link in new tab", enabled: haveMain, click: () => { createTab(p.linkURL); try { win.focus(); } catch {} } },
+        { label: "Open link in new window", click: () => openLinkWindow(p.linkURL) },
+        { label: "Copy link address", click: () => clipboard.writeText(p.linkURL) },
+        { type: "separator" },
+      );
+    }
+    if (p.isEditable) items.push({ role: "cut" }, { role: "copy" }, { role: "paste" }, { type: "separator" });
+    else if (p.selectionText) items.push({ role: "copy" }, { type: "separator" });
+    items.push(
+      { label: "Back", enabled: wc.navigationHistory.canGoBack(), click: () => wc.navigationHistory.goBack() },
+      { label: "Forward", enabled: wc.navigationHistory.canGoForward(), click: () => wc.navigationHistory.goForward() },
+      { label: "Reload", click: () => wc.reload() },
+    );
+    Menu.buildFromTemplate(items).popup({ window: w });
+  });
+  linkWindows.add(w);
+  w.on("closed", () => linkWindows.delete(w));
+  wc.loadURL(target).catch(() => {});
+  return w;
+}
+
 function openHermesWindow() {
   if (hermesWin && !hermesWin.isDestroyed()) {
     hermesWin.focus(); return;
@@ -5056,4 +5142,4 @@ if (!process.env.THESEUS_NO_AUTOSTART) {
   app.on("window-all-closed", () => { stopTor(); if (process.platform !== "darwin") app.quit(); });
 }
 
-module.exports = { serveBns, resolveHost, isBnsHost, nativeTld, dualTld, registryOf };
+module.exports = { serveBns, resolveHost, isBnsHost, nativeTld, dualTld, registryOf, openLinkWindow };