feat: invitation links no longer bound to an e-mail address

A link is redeemable by whoever opens it first, so it can be sent by any
messaging app. The address is optional (mail + label only); a link lives
7 days, fixed. Adds a Share button; see MESHBAY_DESIGN.md §3.4.

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

1 files changed, 34 insertions, 0 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/db/migrations/versions/c4d5e6f7a8b9_invite_links_unbound.py b/packages/meshbay-hub/src/meshbay_hub/db/migrations/versions/c4d5e6f7a8b9_invite_links_unbound.py
new file mode 100644
index 0000000..ae9d2c9
--- /dev/null
+++ b/packages/meshbay-hub/src/meshbay_hub/db/migrations/versions/c4d5e6f7a8b9_invite_links_unbound.py
@@ -0,0 +1,34 @@
+"""invitation links bind no address
+
+A link is now redeemable by whichever account opens it first, so it can be sent
+through any messaging service. The address, when the inviter gives one, is only
+where the hub mails the link and a masked label in the owner's list.
+
+Revision ID: c4d5e6f7a8b9
+Revises: b2c3d4e5f6a7
+"""
+
+from collections.abc import Sequence
+
+import sqlalchemy as sa
+from alembic import op
+
+revision: str = "c4d5e6f7a8b9"
+down_revision: str | Sequence[str] | None = "b2c3d4e5f6a7"
+branch_labels: str | Sequence[str] | None = None
+depends_on: str | Sequence[str] | None = None
+
+
+def upgrade() -> None:
+    with op.batch_alter_table("group_invite_links") as batch:
+        batch.drop_column("email_hash")
+        batch.alter_column("email_masked", existing_type=sa.String(128), nullable=True)
+
+
+def downgrade() -> None:
+    # The bound address cannot be recovered; outstanding links are dropped.
+    op.execute("DELETE FROM group_invite_links")
+    with op.batch_alter_table("group_invite_links") as batch:
+        batch.alter_column("email_masked", existing_type=sa.String(128), nullable=False)
+        batch.add_column(sa.Column("email_hash", sa.String(64), nullable=False,
+                                   server_default=""))