feat(cli): invitations, join, decline, leave, devices, browser access

join accepts an invitation or redeems a link pasted as sent, then has the
node admit a key pair made here, with the invitation's code (a link's code
goes only to the node it names; one for a node that is away is kept for the
next connection). decline, leave and devices revoke ask first, and refuse
without --yes where there is no terminal. devices approve countersigns the
one waiting request a code matches, none when several do. browser-access is
the application's setting, kept per machine and never enabled from the hub's
mirror: on leaves a copy sealed under M on each node, off withdraws it,
unset touches nothing. A key pair made for a first contact is now kept.

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

1 files changed, 31 insertions, 2 deletions

diff --git a/packages/meshbay-cli/src/meshbay_cli/client/keys.py b/packages/meshbay-cli/src/meshbay_cli/client/keys.py
index faca01e..ecf44a5 100644
--- a/packages/meshbay-cli/src/meshbay_cli/client/keys.py
+++ b/packages/meshbay-cli/src/meshbay_cli/client/keys.py
@@ -10,6 +10,7 @@ look like an error — it looks like an account nobody can open.
 import base64
 import hashlib
 import json
+import os
 from dataclasses import dataclass
 
 from argon2.low_level import Type, hash_secret_raw
@@ -77,8 +78,9 @@ def open_bundle(bundle_b64: str, *, master: bytes | None, legacy: bytes | None,
 
     `MBK3` opens under the node's key derived from `M`, with the account and the
     node as associated data. `MBK2` opens under `A` alone; it is read so a member
-    is not locked out of a node still holding one, and never rewritten here —
-    the application or a browser replaces it. Anything older is refused by name.
+    is not locked out of a node still holding one, and never written — an `MBK3`
+    replaces it where this machine leaves bundles (`browser-access on`). Anything
+    older is refused by name.
     """
     try:
         raw = unb64(bundle_b64)
@@ -106,6 +108,33 @@ def open_bundle(bundle_b64: str, *, master: bytes | None, legacy: bytes | None,
     return json.loads(plain)
 
 
+def seal_bundle(keys: dict, *, master: bytes, pepper_version: int, user_id: str,
+                node_pk: str) -> str:
+    """`{skEd, skX}` sealed as `MBK3`, as `keyring.js` `seal` writes it: the magic,
+    the pepper version, a 96-bit nonce, then AES-GCM under the node's bundle key
+    with the account and the node as associated data."""
+    nonce = os.urandom(12)
+    aad = f"meshbay:bundle:v3|{user_id}|{node_pk}".encode()
+    plain = json.dumps({"skEd": keys["skEd"], "skX": keys["skX"]}).encode()
+    ct = AESGCM(node_bundle_key(master, node_pk)).encrypt(nonce, plain, aad)
+    return b64(BUNDLE_MAGIC + bytes([pepper_version & 0xFF]) + nonce + ct)
+
+
+def bundle_is_current(bundle_b64: str, *, master: bytes, user_id: str,
+                      node_pk: str) -> bool:
+    """Whether a bundle is `MBK3` and opens under this `M`: one sealed under an
+    earlier passphrase, or `MBK2`, is to be sealed again."""
+    try:
+        raw = unb64(bundle_b64)
+        if raw[:4] != BUNDLE_MAGIC:
+            return False
+        aad = f"meshbay:bundle:v3|{user_id}|{node_pk}".encode()
+        AESGCM(node_bundle_key(master, node_pk)).decrypt(raw[5:17], raw[17:], aad)
+        return True
+    except Exception:
+        return False
+
+
 @dataclass
 class Identity:
     """One account's keys on one node."""