feat(auth): the recovery key never reaches the hub

Ticking "also e-mail it to me" at registration sent the recovery key R in
the register body, and the hub appended it to the verification e-mail: the
hub saw R in clear on its way out, and the resend door — no captcha — let
anyone who knew a pending username and address have the hub mail a
"recovery key" of their choosing.

The box is gone. The recovery screen offers "E-mail it to myself", a mailto:
link that opens the person's own mail application with the key filled in;
the desktop shell hands mailto: to the system (http, https and mailto only)
and the Android shell to a mail application (ACTION_SENDTO). The CLI drops
--email-recovery-key and prints the key, as before. The hub mails the code
alone, and refuses a register that still carries a recovery_key rather than
dropping it, so an older client offering the option cannot tell someone
their key was sent when it was not.

A mailbox holding R remains, with the reset code that reaches the same
mailbox, enough to recover the account's identities; the link says so, and
it is the person's choice.

Checked in Chrome and Firefox (headless, the real page against a stubbed
hub) and by the CLI's end-to-end registration against a local hub. The
Android change was not built here, and the desktop link was not clicked in
the application.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

1 files changed, 3 insertions, 1 deletions

diff --git a/packages/meshbay-client/src/main.js b/packages/meshbay-client/src/main.js
index b602950..b77022e 100644
--- a/packages/meshbay-client/src/main.js
+++ b/packages/meshbay-client/src/main.js
@@ -682,8 +682,10 @@ function createWindow() {
   win.webContents.on('will-navigate', (event, target) => {
     if (!isOurs(target)) event.preventDefault();
   });
+  // `mailto:` goes to the system's mail application too: the recovery screen
+  // has the person mail their key to themselves (docs/MESHBAY_DESIGN.md §3.6).
   win.webContents.setWindowOpenHandler(({ url }) => {
-    if (/^https?:$/.test(new URL(url).protocol)) shell.openExternal(url);
+    if (/^(https?|mailto):$/.test(new URL(url).protocol)) shell.openExternal(url);
     return { action: 'deny' };
   });
   // Deny by default, with one exception, and the exception is the point of the