feat: open a group, a folder or a file from a #/name@owner link

A group can now be reached by the handle shown under its name, and a path
after it points inside the group: #/name@owner/root/dir/file downloads the
file and opens Files on its folder; a folder opens Files there. The handle
is resolved in the client against the account's own /v1/groups/mine, so no
hub route answers for a name and nobody can probe for one. While a group is
open the address shows the handle (replace, no history entry); a linked path
is taken out of the address once acted on, so a reload does not download
twice.

Signing in no longer sends everyone home: the form stood in for the page the
address named, and that is where a link opened signed out was going.

group-link.js holds the parsing and lookups, executed whole by
test_group_link.py; harness/group_link_probe.py drives the router in Chrome.

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

1 files changed, 6 insertions, 2 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/static/auth-page.js b/packages/meshbay-hub/src/meshbay_hub/static/auth-page.js
index c12db72..57db475 100644
--- a/packages/meshbay-hub/src/meshbay_hub/static/auth-page.js
+++ b/packages/meshbay-hub/src/meshbay_hub/static/auth-page.js
@@ -185,8 +185,12 @@ export function LoginPage({ onLogin }) {
       // Trimmed to match the hub's stored username and every client-side key
       // derivation (auth_key, bundle_key, recovery_key all fold the username in).
       await onLogin(name, password);
-      // Back to the invitation that sent them here, if one is waiting.
-      navigate(loadPending() ? '/invite' : '/');
+      // Back to the invitation that sent them here, if one is waiting. Otherwise
+      // nowhere: on `#/login` or `#/register` the router sends a signed-in
+      // person home itself, and anywhere else this form stood in for the page
+      // the address names — a group, a file in one — which is where they were
+      // going. Sending everyone home lost every link opened signed out.
+      if (loadPending()) navigate('/invite');
     } catch (err) {
       if (err.message === 'email_verification_required') {
         setPendingVerif(true);