fix(hub): a username is unique whatever its case

Registration refuses a name that differs from an existing one only by case;
accounts that already do keep their names, and a pending retry needs the exact
name (F-26).

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

1 files changed, 4 insertions, 1 deletions

diff --git a/docs/MESHBAY_DESIGN.md b/docs/MESHBAY_DESIGN.md
index e07f03b..3625698 100644
--- a/docs/MESHBAY_DESIGN.md
+++ b/docs/MESHBAY_DESIGN.md
@@ -213,7 +213,10 @@ design; reading what *other* operators host is not, and does not follow (§3.2).
 
 An account lives on the hub: a username, an encrypted email address, a status and
 a role. A username is 8 to 64 characters, checked at registration only — accounts
-created under the older 3-character floor keep signing in. The passphrase never leaves the client. It derives **two independent
+created under the older 3-character floor keep signing in — and **unique whatever
+its case**: invitations and member management name people by username, and
+"Alice" beside "alice" is one person to whoever reads the list. Sign-in takes the
+name as stored. The passphrase never leaves the client. It derives **two independent
 values**, both salted by the trimmed username:
 
 | Value | Derivation | Consumer |