feat(node)!: the node wraps the group key — closes H3 and M3

The invite flow fetched the invitee's pk_x25519 from the hub and wrapped the
GEK for whatever came back (app.js:1466, and gek-init did the same server-side).
The hub is the key directory, so a hub answering with its own key was handed the
group key by an honest member following the protocol exactly. No forgery, no
injection, nothing for the client to notice. That was H3.

The fix is not safety numbers. Nobody reads the directory any more:

  - the node holds the GEK and wraps it itself, on every connection, for the
    X25519 key the joiner signed with their Ed25519 identity in one transcript
    (meshbay:join:v1), so the identity key vouches for the encryption key;
  - identities are bound to accounts by a one-time code the hub never sees —
    40 bits, single use, one account, bounded per connection AND node-wide;
  - the node's own roster decides who may receive the key. Hub membership lets
    someone reach a node; it no longer gets them anything. A hub that invents an
    account and mints it a token is answered not_authorized_for_group.

Safety numbers would have made substitution detectable by a human who checks, at
the moment there is nothing to check against — first contact. Removing the lookup
makes it impossible, and costs the user one code to pass along.

M3 falls out of the same work. The daemon auto-pinned its own keystore key as
admin_pk_ed25519 while the browser signs with the user identity key, so every
privileged operation failed closed with a signature error that looked like a bug
somewhere else; the demo only worked because a deploy script overwrote the value.
Authority now comes from the roster, established locally by `operator pair`.
Asking the hub for the operator's key — the obvious-looking fix — would have let
the hub install itself as node administrator.

BREAKING: gek_bundle_store is deleted, not gated. No member hands the node key
material at all, so C5b becomes structural rather than an authorization to check.
Existing stored bundles are still served, so current deployments keep working.

Also:
  - join_policy (invite|open) is read from node.toml, never from the hub — a hub
    able to declare a group open would be handed its key. Unknown group ⇒ invite.
  - admin signatures are verified against the roster on every check, so unpinning
    takes effect without a restart. admin_pk_ed25519 stays readable as legacy.
  - two C5b tests were rewritten, deliberately: they asserted that
    gek_bundle_store demanded an operator signature, and the message is gone. They
    now assert the stronger property. The file says not to fix these tests, so
    this is the record of why they changed.
  - a slice-1 bug found while writing slice 2: connect() never passed skEdB64, so
    pairing would have failed at runtime with no test able to catch it.

Tests: 152 node+common here, including an end-to-end DataChannel run where a
member who has never held the group key redeems a code in the pre-proof window
and receives the key wrapped for a key only they can open.

Design: docs/invite-pairing-v1.md

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

5 files changed, 979 insertions, 159 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/config.py b/packages/meshbay-node/src/meshbay_node/config.py
index b681355..04cb1d3 100644
--- a/packages/meshbay-node/src/meshbay_node/config.py
+++ b/packages/meshbay-node/src/meshbay_node/config.py
@@ -44,7 +44,10 @@ id          = ""
 name        = "Public Archive"
 shared_dir  = "/home/user/Archive"
 quic_port   = 19012
-visibility  = "public"
+visibility  = "public"       # discoverable on the hub
+# join_policy = "open"       # anyone the hub says is a member gets the group key,
+                             # with no pairing code. Only for groups where that is
+                             # genuinely intended: it means the hub can join too.
 
 [keystore]
 # unlock_file = "~/.config/meshbay/unlock.key"
@@ -74,7 +77,15 @@ class GroupConfig:
     id:         str = ""
     name:       str = ""
     shared_dir: str = ""
-    visibility: str = "private"   # public|private
+    visibility: str = "private"   # public|private — discoverability, not admission
+    # Admission. "invite" (default) means a newcomer needs a one-time pairing code
+    # before the node wraps the group key for them; "open" means the node pins
+    # whoever turns up first (TOFU) and serves them.
+    #
+    # Deliberately read from THIS file and never from the hub: a hub that could
+    # declare a group open would walk into any group it liked. Being findable
+    # (`visibility`) and being open (`join_policy`) are different questions.
+    join_policy: str = "invite"   # invite|open
     quic_port:  int = 19010       # QUIC MNP port
 
 
@@ -127,6 +138,7 @@ def load_config(path: Path = DEFAULT_CONFIG_PATH) -> Config:
                     name=g.get("name", ""),
                     shared_dir=g.get("shared_dir", ""),
                     visibility=g.get("visibility", "private"),
+                    join_policy=g.get("join_policy", "invite"),
                     quic_port=g.get("quic_port", cfg.node.quic_port),
                 ))
         # Back-compat: single [group] section
diff --git a/packages/meshbay-node/src/meshbay_node/daemon.py b/packages/meshbay-node/src/meshbay_node/daemon.py
index 46a1716..7f84abe 100644
--- a/packages/meshbay-node/src/meshbay_node/daemon.py
+++ b/packages/meshbay-node/src/meshbay_node/daemon.py
@@ -45,7 +45,8 @@ from meshbay_node.chat.store import ChatStore
 from meshbay_node.config import Config, DEFAULT_CONFIG_PATH, load_config, write_example_config
 from meshbay_node.hub_client import HubClient, HubConfig
 from meshbay_node.indexer import DirectoryIndexer
-from meshbay_node.keystore import NodeKeys, load_or_create_keystore
+from meshbay_node.keystore import load_or_create_keystore
+from meshbay_node.roster import Roster
 from meshbay_node.transport import (
     Denylist,
     QUIC_AVAILABLE,
@@ -117,6 +118,7 @@ class NodeDaemon:
         self._chat_stores: dict[str, ChatStore] = {}
         self._audit_store: AuditStore | None = None
         self._bundle_store: BundleStore | None = None
+        self._roster: Roster | None = None
         self._indexers: list[DirectoryIndexer] = []
         self._tasks: list[asyncio.Task] = []
         self._hub: HubClient | None = None
@@ -174,6 +176,14 @@ class NodeDaemon:
             await self._bundle_store.open()
             log.info("Bundle store opened: %s", data_dir / "bundles.db")
 
+            # 4b. Roster — who this node recognises and which keys are theirs.
+            # Node authority is established here, locally, and never learned from
+            # the hub: a hub that could name the operator's key could install
+            # itself as node administrator.
+            self._roster = Roster(db_path=data_dir / "roster.db")
+            await self._roster.open()
+            await self._roster.purge_expired()
+
             # X25519 key material for GEK unwrapping
             from cryptography.hazmat.primitives import serialization
             sk_x_raw = keys.sk_x25519.private_bytes(
@@ -223,6 +233,9 @@ class NodeDaemon:
                     "shared_root": shared_root,
                     "index": indexer.index,
                     "visibility": group_cfg.visibility,
+                    # Admission policy comes from node.toml, never from the hub:
+                    # a hub that could declare a group open would be handed its key.
+                    "join_policy": group_cfg.join_policy,
                 }
 
             if not groups_ctx:
@@ -272,12 +285,20 @@ class NodeDaemon:
                 self._webrtc._ctx["pk_x25519_raw"] = pk_x_raw
                 self._webrtc._ctx["pk_x25519_b64"] = keys.pk_x25519_b64
 
-                admin_pk = self._resolve_admin_pk(keys)
+                self._webrtc._ctx["roster"] = self._roster
+                admin_pk = self._legacy_admin_pk()
+                paired = await self._roster.has_operator() if self._roster else False
                 if admin_pk:
                     self._webrtc._ctx["admin_pk_ed25519"] = admin_pk
-                    log.info("Admin Ed25519 key pinned for node sovereignty")
+                self._webrtc._ctx["has_admin_authority"] = paired
+                if paired or admin_pk:
+                    sources = ([] if not paired else ["paired operator"]) + \
+                              ([] if not admin_pk else ["node.toml admin_pk"])
+                    log.info("Node authority: %s", " + ".join(sources))
                 else:
-                    log.warning("No admin_pk_ed25519 — admin operations disabled")
+                    log.warning(
+                        "No operator paired — invites and file deletion are "
+                        "refused. Run: meshbay-node operator pair")
                 log.info("WebRTC transport ready")
             else:
                 log.warning("WebRTC not available (aiortc not installed)")
@@ -358,6 +379,8 @@ class NodeDaemon:
             self._state["groups_ctx"] = groups_ctx
             self._state["audit_store"] = self._audit_store
             self._state["bundle_store"] = self._bundle_store
+            self._state["roster"] = self._roster
+            self._state["node_user_id"] = session.user_id
             self._state["webrtc"] = self._webrtc
             self._state["hub"] = hub
             self._state["pk_x25519_raw"] = pk_x_raw
@@ -457,21 +480,25 @@ class NodeDaemon:
         log.warning("No unwrappable GEK bundle found for group %s", group_id[:8])
         return None
 
-    def _resolve_admin_pk(self, keys: NodeKeys) -> Ed25519PublicKey | None:
-        """Resolve the admin Ed25519 public key: config → auto-pin from node keystore."""
-        if self._config.admin_pk_ed25519:
-            try:
-                raw = base64.b64decode(self._config.admin_pk_ed25519)
-                return Ed25519PublicKey.from_public_bytes(raw)
-            except Exception as e:
-                log.error("Invalid admin_pk_ed25519 in config: %s", e)
-                return None
+    def _legacy_admin_pk(self) -> Ed25519PublicKey | None:
+        """
+        The pre-roster way of naming the operator: `admin_pk_ed25519` in node.toml.
 
-        pk = keys.sk_ed25519.public_key()
-        from meshbay_common.crypto import pk_to_b64
-        pk_b64 = pk_to_b64(pk)
-        log.info("Auto-pinning admin key from node keystore: %s", pk_b64[:16])
-        return pk
+        Still honoured so a deployment configured that way keeps working, but no
+        longer the only path — and the auto-pin that used to stand in for it is
+        gone. It pinned the node's *keystore* key while the browser signed with the
+        user's *identity* key, so admin operations failed closed with a signature
+        error that looked like a bug elsewhere (finding M3). An operator now pairs
+        a browser with `meshbay-node operator pair`.
+        """
+        if not self._config.admin_pk_ed25519:
+            return None
+        try:
+            raw = base64.b64decode(self._config.admin_pk_ed25519)
+            return Ed25519PublicKey.from_public_bytes(raw)
+        except Exception as e:
+            log.error("Invalid admin_pk_ed25519 in config: %s", e)
+            return None
 
     async def _on_index_change(self, indexer: DirectoryIndexer) -> None:
         """Called when a DirectoryIndexer detects file changes."""
@@ -554,6 +581,9 @@ class NodeDaemon:
         if self._bundle_store:
             await self._bundle_store.close()
 
+        if self._roster:
+            await self._roster.close()
+
         for store in self._chat_stores.values():
             await store.close()
 
@@ -570,6 +600,60 @@ class NodeDaemon:
         log.info("Node stopped")
 
 
+# ── CLI helpers ───────────────────────────────────────────────────────────────
+
+def _daemon_api(cfg: Config, path: str, method: str = "GET",
+                timeout: int = 30) -> dict:
+    """
+    Call the daemon's loopback API.
+
+    The daemon owns the roster, the hub session and the live group contexts, so
+    the CLI asks it to act rather than opening its databases behind its back. It
+    also means every operator action goes through the same authorization as the
+    admin UI (the per-run session token, 11.5.3).
+    """
+    import json as _json
+    import urllib.error
+    import urllib.parse
+    import urllib.request
+
+    token_file = cfg.data_dir / "ui-token"
+    if not token_file.exists():
+        print("Node is not running — start it with: meshbay-node")
+        sys.exit(1)
+
+    sep = "&" if "?" in path else "?"
+    url = (f"http://127.0.0.1:{cfg.node.ui_port}{path}"
+           f"{sep}t={token_file.read_text().strip()}")
+    try:
+        req = urllib.request.Request(url, method=method)
+        with urllib.request.urlopen(req, timeout=timeout) as r:
+            return _json.loads(r.read())
+    except urllib.error.HTTPError as e:
+        body = e.read().decode()[:300]
+        try:
+            detail = _json.loads(body).get("error", body)
+        except Exception:
+            detail = body
+        print(f"failed: {detail}")
+        sys.exit(1)
+    except Exception as e:
+        print(f"failed: {e}")
+        sys.exit(1)
+
+
+def _resolve_group(cfg: Config, group: str | None) -> str:
+    """The group argument, or the only configured one."""
+    if group:
+        return group
+    configured = [g.id for g in cfg.groups if g.id]
+    if len(configured) == 1:
+        return configured[0]
+    print("--group is required (several groups configured)"
+          if configured else "no group configured in node.toml")
+    sys.exit(1)
+
+
 # ── Entry point ───────────────────────────────────────────────────────────────
 
 def main() -> None:
@@ -577,19 +661,23 @@ def main() -> None:
 
     parser = argparse.ArgumentParser(description="MeshBay Node daemon")
     parser.add_argument("command", nargs="?",
-                        choices=["init", "status", "ui", "gek-init", "calibrate-argon2"],
+                        choices=["init", "status", "ui", "gek-init", "operator",
+                                 "calibrate-argon2"],
                         help="init: write example config | status: node state and keys "
-                             "| ui: print the admin UI URL | calibrate-argon2: benchmark")
+                             "| ui: print the admin UI URL | operator pair: pair a "
+                             "browser with this node | calibrate-argon2: benchmark")
+    parser.add_argument("subcommand", nargs="?",
+                        help="'pair' for the operator command")
     parser.add_argument("--config", type=Path, default=None,
                         help="Config file path")
     parser.add_argument("--group", default=None,
-                        help="group id for gek-init (optional if only one is configured)")
+                        help="group id (optional if only one is configured)")
     parser.add_argument("--log-level", default="INFO",
                         choices=["DEBUG", "INFO", "WARNING", "ERROR"])
     args = parser.parse_args()
 
     # Query commands print a report; library logging would interleave with it.
-    quiet = args.command in ("status", "ui", "gek-init")
+    quiet = args.command in ("status", "ui", "gek-init", "operator")
     logging.basicConfig(
         level=logging.ERROR if quiet else getattr(logging, args.log_level),
         format="%(asctime)s %(levelname)-8s %(name)s: %(message)s",
@@ -649,50 +737,79 @@ def main() -> None:
             for g in cfg.groups:
                 print(f"  group      {g.name} [{g.visibility}] {g.id or '<no id>'}")
                 print(f"             {g.shared_dir or '<no shared_dir>'}")
-        if not cfg.admin_pk_ed25519:
-            print("admin key    NOT pinned — file deletion and member invites will be")
-            print("             refused (node.toml: admin_pk_ed25519)")
-        return
-
-    if args.command == "gek-init":
-        import json as _json
-        import urllib.error
-        import urllib.request
+        # Node authority: the roster is the source of truth, node.toml the legacy
+        # form. Read the DB directly so this reports correctly while the daemon is
+        # stopped — the state an operator is most often in when checking.
+        import asyncio as _asyncio
 
-        cfg = load_config(args.config or DEFAULT_CONFIG_PATH)
-        group_id = args.group
-        if not group_id:
-            if len(cfg.groups) == 1:
-                group_id = cfg.groups[0].id
-            else:
-                print("--group is required (several groups configured)")
-                sys.exit(1)
+        from meshbay_node.roster import Roster as _Roster
 
-        token_file = cfg.data_dir / "ui-token"
-        if not token_file.exists():
-            print("Node is not running — start it with: meshbay-node")
-            sys.exit(1)
+        async def _read_roster() -> tuple[list, int]:
+            r = _Roster(db_path=cfg.data_dir / "roster.db")
+            await r.open()
+            try:
+                return (await r.list_members()), len(await r.list_invites())
+            finally:
+                await r.close()
 
-        # The daemon holds the hub session and the live group contexts, so the CLI
-        # asks it to do the work rather than duplicating it. Same operation as the
-        # admin UI button — an operator on a headless host should never need a
-        # browser on that host to initialise a group key.
-        url = (f"http://127.0.0.1:{cfg.node.ui_port}/api/groups/{group_id}/gek"
-               f"?t={token_file.read_text().strip()}")
         try:
-            req = urllib.request.Request(url, method="POST")
-            with urllib.request.urlopen(req, timeout=60) as r:
-                out = _json.loads(r.read())
-        except urllib.error.HTTPError as e:
-            print(f"failed: {e.code} {e.read().decode()[:300]}")
-            sys.exit(1)
+            members, pending = _asyncio.run(_read_roster())
+        except Exception as e:
+            members, pending = [], 0
+            print(f"roster       <unreadable: {e}>")
+
+        operators = [m for m in members if m["role"] == "operator"
+                     and m["status"] == "active"]
+        if operators:
+            for op in operators:
+                print(f"operator     {op.get('username') or op['user_id'][:8]}"
+                      f"  key {(op.get('pk_ed25519') or '')[:16]}…"
+                      f"  paired {op.get('pinned_at', '?')}")
+        elif cfg.admin_pk_ed25519:
+            print("operator     node.toml admin_pk_ed25519 (legacy)")
+            print("             run `meshbay-node operator pair` to replace it")
+        else:
+            print("operator     NONE PAIRED — file deletion and member invites are")
+            print("             refused. Run: meshbay-node operator pair")
+        if pending:
+            print(f"invites      {pending} pending code(s)")
+        return
+
+    if args.command == "gek-init":
+        cfg = load_config(args.config or DEFAULT_CONFIG_PATH)
+        group_id = _resolve_group(cfg, args.group)
+        out = _daemon_api(cfg, f"/api/groups/{group_id}/gek",
+                          method="POST", timeout=60)
 
         print(f"GEK ready for {group_id}")
-        print(f"  wrapped for {out.get('wrapped_count')}/{out.get('total_members')} members")
+        print(f"  {out.get('authorized_members', 0)} authorized member(s) — each "
+              f"receives the key on connect")
         for err in out.get("errors") or []:
             print(f"  ! {err}")
         return
 
+    if args.command == "operator":
+        if args.subcommand != "pair":
+            print("usage: meshbay-node operator pair")
+            sys.exit(1)
+
+        cfg = load_config(args.config or DEFAULT_CONFIG_PATH)
+        out = _daemon_api(cfg, "/api/operator/pair", method="POST")
+
+        from meshbay_node.roster import write_code_file
+        path = write_code_file(cfg.data_dir, out["code"], out.get("expires_at", ""))
+
+        print(f"PAIRING CODE   {out['code']}")
+        print(f"valid until    {out.get('expires_at', '?')}")
+        print()
+        print("Sign in to the web app as this node's operator, open one of your")
+        print("groups, go to the Members tab and enter the code there.")
+        print("It works once, for that account only, and authorizes invites and")
+        print("file deletion from that browser.")
+        print()
+        print(f"also written to {path}")
+        return
+
     if args.command == "ui":
         cfg = load_config(args.config or DEFAULT_CONFIG_PATH)
         token_file = cfg.data_dir / "ui-token"
diff --git a/packages/meshbay-node/src/meshbay_node/roster.py b/packages/meshbay-node/src/meshbay_node/roster.py
new file mode 100644
index 0000000..f231792
--- /dev/null
+++ b/packages/meshbay-node/src/meshbay_node/roster.py
@@ -0,0 +1,372 @@
+"""
+Node roster — who this node recognises, and which keys are theirs.
+
+The node keeps its own answer to "may this person have the group key", derived from
+what the operator authorized locally. It is deliberately NOT derived from the hub:
+the hub decides group membership, and a hub that invents an account and mints a
+token for it would otherwise collect the GEK on connect. Hub membership is an input
+to the decision; it is not the decision.
+
+Three tables:
+
+  identities — one row per person, not per group. Someone paired for one group
+               needs no code for the next one on the same node.
+  members    — role and status per (group, user).
+  invites    — one-time pairing codes, stored as a hash. The code itself exists
+               only in the operator's hands and the invitee's.
+
+The code is what binds a public key to an account without asking the hub
+(finding H3). See `docs/invite-pairing-v1.md`.
+"""
+
+from __future__ import annotations
+
+import hashlib
+import logging
+import os
+import secrets
+from datetime import datetime, timedelta, timezone
+from pathlib import Path
+
+import aiosqlite
+
+log = logging.getLogger(__name__)
+
+# Crockford base32 without I, L, O and U: no character pair a human can confuse
+# when reading a code aloud or typing it from a phone screen.
+_ALPHABET = "0123456789ABCDEFGHJKMNPQRSTVWXYZ"
+CODE_LEN = 8                      # 8 × 5 bits = 40 bits of entropy
+DEFAULT_INVITE_TTL = 24 * 3600    # seconds
+
+_SCHEMA = """\
+CREATE TABLE IF NOT EXISTS identities (
+    user_id    TEXT PRIMARY KEY,
+    username   TEXT NOT NULL,
+    pk_ed25519 TEXT NOT NULL,
+    pk_x25519  TEXT NOT NULL,
+    pinned_at  TEXT NOT NULL,
+    pinned_via TEXT NOT NULL
+);
+
+CREATE TABLE IF NOT EXISTS members (
+    group_id    TEXT NOT NULL,
+    user_id     TEXT NOT NULL,
+    role        TEXT NOT NULL,
+    status      TEXT NOT NULL,
+    approved_by TEXT NOT NULL,
+    approved_at TEXT NOT NULL,
+    PRIMARY KEY (group_id, user_id)
+);
+
+CREATE TABLE IF NOT EXISTS invites (
+    code_hash  TEXT PRIMARY KEY,
+    group_id   TEXT NOT NULL,
+    user_id    TEXT NOT NULL,
+    role       TEXT NOT NULL,
+    created_by TEXT NOT NULL,
+    created_at TEXT NOT NULL,
+    expires_at TEXT NOT NULL,
+    used_at    TEXT
+);
+"""
+
+
+def generate_code() -> str:
+    """A fresh pairing code, formatted for a human to read out: XXXX-XXXX."""
+    raw = "".join(secrets.choice(_ALPHABET) for _ in range(CODE_LEN))
+    return f"{raw[:4]}-{raw[4:]}"
+
+
+def normalize_code(code: str) -> str:
+    """
+    Fold what a human typed onto what was generated.
+
+    Crockford's rules: case-insensitive, dashes and spaces are decoration, and the
+    excluded letters map onto the digits they resemble. Someone reading a code over
+    the phone should not be able to get it wrong in a way we could have absorbed.
+    """
+    out = []
+    for ch in code.upper():
+        if ch in "- \t":
+            continue
+        if ch in "IL":
+            out.append("1")
+        elif ch == "O":
+            out.append("0")
+        elif ch == "U":
+            out.append("V")
+        else:
+            out.append(ch)
+    return "".join(out)
+
+
+def hash_code(code: str) -> str:
+    """
+    Store codes hashed: a stolen roster DB must not yield usable invitations.
+
+    SHA-256 rather than a password KDF on purpose — the input is 40 bits of
+    uniformly random secret, not a human-chosen string, so there is nothing for a
+    slow hash to defend.
+    """
+    return hashlib.sha256(normalize_code(code).encode()).hexdigest()
+
+
+def _now() -> str:
+    return datetime.now(timezone.utc).isoformat(timespec="seconds")
+
+
+class Roster:
+    def __init__(self, db_path: Path):
+        self._db_path = db_path
+        self._db: aiosqlite.Connection | None = None
+
+    async def open(self) -> None:
+        self._db_path.parent.mkdir(parents=True, exist_ok=True)
+        self._db = await aiosqlite.connect(str(self._db_path))
+        self._db.row_factory = aiosqlite.Row
+        # WAL: the CLI writes invites (`operator pair`) while the daemon reads them.
+        await self._db.execute("PRAGMA journal_mode=WAL")
+        await self._db.executescript(_SCHEMA)
+        await self._db.commit()
+
+    async def close(self) -> None:
+        if self._db:
+            await self._db.close()
+            self._db = None
+
+    # ── Identities ───────────────────────────────────────────────────────────
+
+    async def pin_identity(
+        self,
+        user_id: str,
+        username: str,
+        pk_ed25519: str,
+        pk_x25519: str,
+        via: str,
+    ) -> None:
+        assert self._db
+        await self._db.execute(
+            "INSERT OR REPLACE INTO identities "
+            "(user_id, username, pk_ed25519, pk_x25519, pinned_at, pinned_via) "
+            "VALUES (?, ?, ?, ?, ?, ?)",
+            (user_id, username, pk_ed25519, pk_x25519, _now(), via),
+        )
+        await self._db.commit()
+
+    async def get_identity(self, user_id: str) -> dict | None:
+        assert self._db
+        async with self._db.execute(
+            "SELECT * FROM identities WHERE user_id = ?", (user_id,)
+        ) as cur:
+            row = await cur.fetchone()
+        return dict(row) if row else None
+
+    async def unpin(self, user_id: str) -> bool:
+        assert self._db
+        cur = await self._db.execute(
+            "DELETE FROM identities WHERE user_id = ?", (user_id,))
+        await self._db.commit()
+        return cur.rowcount > 0
+
+    async def list_identities(self) -> list[dict]:
+        assert self._db
+        async with self._db.execute(
+            "SELECT * FROM identities ORDER BY pinned_at"
+        ) as cur:
+            return [dict(r) for r in await cur.fetchall()]
+
+    # ── Authority ────────────────────────────────────────────────────────────
+
+    async def operator_pks(self) -> list[str]:
+        """
+        Base64 Ed25519 keys allowed to authorize admin operations on this node.
+
+        Read fresh on every check rather than cached: an unpin must take effect at
+        once, and this runs only on admin operations, which are rare.
+        """
+        assert self._db
+        async with self._db.execute(
+            "SELECT i.pk_ed25519 FROM identities i "
+            "JOIN members m ON m.user_id = i.user_id "
+            "WHERE m.role = 'operator' AND m.status = 'active'"
+        ) as cur:
+            return [r["pk_ed25519"] for r in await cur.fetchall()]
+
+    async def has_operator(self) -> bool:
+        return bool(await self.operator_pks())
+
+    async def is_authorized(self, group_id: str, user_id: str) -> bool:
+        """
+        May this person be handed the group key?
+
+        The node's own answer, not the hub's. Hub membership is what lets someone
+        reach the node; this is what decides whether the key is wrapped for them —
+        otherwise a hub that invents an account and mints a token for it would be
+        served the GEK on connect.
+
+        An operator is authorized for every group this node hosts: their authority
+        is node-wide and is recorded with an empty group_id.
+        """
+        assert self._db
+        async with self._db.execute(
+            "SELECT 1 FROM members WHERE user_id = ? AND status = 'active' "
+            "AND (group_id = ? OR (group_id = '' AND role = 'operator')) LIMIT 1",
+            (user_id, group_id),
+        ) as cur:
+            return await cur.fetchone() is not None
+
+    # ── Members ──────────────────────────────────────────────────────────────
+
+    async def set_member(
+        self,
+        group_id: str,
+        user_id: str,
+        role: str,
+        status: str,
+        approved_by: str,
+    ) -> None:
+        assert self._db
+        await self._db.execute(
+            "INSERT OR REPLACE INTO members "
+            "(group_id, user_id, role, status, approved_by, approved_at) "
+            "VALUES (?, ?, ?, ?, ?, ?)",
+            (group_id, user_id, role, status, approved_by, _now()),
+        )
+        await self._db.commit()
+
+    async def get_member(self, group_id: str, user_id: str) -> dict | None:
+        assert self._db
+        async with self._db.execute(
+            "SELECT * FROM members WHERE group_id = ? AND user_id = ?",
+            (group_id, user_id),
+        ) as cur:
+            row = await cur.fetchone()
+        return dict(row) if row else None
+
+    async def list_members(self, group_id: str | None = None) -> list[dict]:
+        assert self._db
+        sql = (
+            "SELECT m.*, i.username, i.pk_ed25519, i.pinned_at, i.pinned_via "
+            "FROM members m LEFT JOIN identities i ON i.user_id = m.user_id"
+        )
+        args: tuple = ()
+        if group_id is not None:
+            sql += " WHERE m.group_id = ?"
+            args = (group_id,)
+        async with self._db.execute(sql + " ORDER BY m.approved_at", args) as cur:
+            return [dict(r) for r in await cur.fetchall()]
+
+    async def set_status(self, group_id: str, user_id: str, status: str) -> bool:
+        assert self._db
+        cur = await self._db.execute(
+            "UPDATE members SET status = ? WHERE group_id = ? AND user_id = ?",
+            (status, group_id, user_id),
+        )
+        await self._db.commit()
+        return cur.rowcount > 0
+
+    # ── Invites ──────────────────────────────────────────────────────────────
+
+    async def create_invite(
+        self,
+        group_id: str,
+        user_id: str,
+        role: str,
+        created_by: str,
+        ttl: int = DEFAULT_INVITE_TTL,
+    ) -> str:
+        """
+        Issue a one-time code. Returns it in the clear — this is the only moment it
+        exists outside the operator's hands; only its hash is kept.
+
+        Any earlier unused invite for the same person and group is dropped, so
+        re-inviting supersedes rather than accumulating valid codes.
+        """
+        assert self._db
+        await self._db.execute(
+            "DELETE FROM invites WHERE group_id = ? AND user_id = ? AND used_at IS NULL",
+            (group_id, user_id),
+        )
+        code = generate_code()
+        expires = datetime.now(timezone.utc) + timedelta(seconds=ttl)
+        await self._db.execute(
+            "INSERT INTO invites "
+            "(code_hash, group_id, user_id, role, created_by, created_at, expires_at) "
+            "VALUES (?, ?, ?, ?, ?, ?, ?)",
+            (hash_code(code), group_id, user_id, role, created_by, _now(),
+             expires.isoformat(timespec="seconds")),
+        )
+        await self._db.commit()
+        return code
+
+    async def consume_invite(self, code: str, user_id: str) -> dict | None:
+        """
+        Redeem a code for `user_id`, or return None.
+
+        Single use is enforced by the UPDATE's WHERE clause: two connections racing
+        the same code cannot both see `used_at IS NULL`, so exactly one wins.
+        """
+        assert self._db
+        code_hash = hash_code(code)
+        async with self._db.execute(
+            "SELECT * FROM invites WHERE code_hash = ?", (code_hash,)
+        ) as cur:
+            row = await cur.fetchone()
+        if not row:
+            return None
+
+        invite = dict(row)
+        if invite["used_at"] is not None:
+            return None
+        # A code is valid for exactly one account, so a leaked code cannot be
+        # redeemed by whoever finds it first.
+        if invite["user_id"] != user_id:
+            return None
+        if datetime.fromisoformat(invite["expires_at"]) < datetime.now(timezone.utc):
+            return None
+
+        cur = await self._db.execute(
+            "UPDATE invites SET used_at = ? WHERE code_hash = ? AND used_at IS NULL",
+            (_now(), code_hash),
+        )
+        await self._db.commit()
+        if cur.rowcount == 0:
+            return None
+        return invite
+
+    async def list_invites(self, include_used: bool = False) -> list[dict]:
+        assert self._db
+        sql = "SELECT * FROM invites"
+        if not include_used:
+            sql += " WHERE used_at IS NULL"
+        async with self._db.execute(sql + " ORDER BY created_at") as cur:
+            return [dict(r) for r in await cur.fetchall()]
+
+    async def purge_expired(self) -> int:
+        assert self._db
+        cur = await self._db.execute(
+            "DELETE FROM invites WHERE used_at IS NULL AND expires_at < ?",
+            (_now(),),
+        )
+        await self._db.commit()
+        return cur.rowcount
+
+
+async def open_roster(data_dir: Path) -> Roster:
+    roster = Roster(data_dir / "roster.db")
+    await roster.open()
+    return roster
+
+
+def write_code_file(data_dir: Path, code: str, expires_at: str) -> Path:
+    """
+    Leave the code in a file as well as on stdout.
+
+    An operator working over SSH may not be able to copy out of their terminal,
+    and a code that can only be read off a scrolled-away screen is a dead end.
+    """
+    path = data_dir / "pair-code"
+    path.parent.mkdir(parents=True, exist_ok=True)
+    path.write_text(f"{code}\nexpires {expires_at}\n")
+    os.chmod(path, 0o600)
+    return path
diff --git a/packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py b/packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py
index 34a96bd..fe3ee2e 100644
--- a/packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py
+++ b/packages/meshbay-node/src/meshbay_node/transport/webrtc_server.py
@@ -57,10 +57,16 @@ from meshbay_common.handshake import (
 from meshbay_common.adminop import (
     ADMIN_CHALLENGE_TTL,
     OP_FILE_DELETE,
-    OP_GEK_BUNDLE_STORE,
+    OP_INVITE_CREATE,
     admin_transcript,
 )
-from meshbay_common.crypto import pk_to_b64
+from meshbay_common.crypto import pk_to_b64, wrap_gek_aes
+from meshbay_common.join import (
+    JOIN_TTL,
+    ROLE_MEMBER,
+    ROLE_OPERATOR,
+    join_transcript,
+)
 from meshbay_common.webcrypto import chunk_key_aes, encrypt_chunk_aes
 from meshbay_common.protocol import MNP
 from meshbay_node.indexer import GroupIndex
@@ -85,6 +91,14 @@ MAX_CONCURRENT_TRANSCODES = 2
 # Bundle fetches are served in the pre-proof window (C4). Bounded and audited
 # until the native client removes remote keypair bundles entirely.
 MAX_PRE_PROOF_FETCHES = 4
+# Pairing codes carry 40 bits and are single-use, but a connection must not be
+# allowed to sit there guessing. Failures are audited, so a grind is visible.
+MAX_JOIN_ATTEMPTS = 5
+# Per-connection limits alone would not bind an attacker who can open connections
+# at will — and the adversary who can mint tokens for any account is the hub. So
+# failed pairings are also counted node-wide over a window.
+MAX_JOIN_FAILURES_WINDOW = 20
+JOIN_FAILURE_WINDOW = 600  # seconds
 UPLOAD_DIR_NAME = ".uploads"
 # Conservative allowlist: also what keeps markup out of filenames, which the node admin
 # UI used to render unescaped (finding H2).
@@ -218,6 +232,11 @@ class WebRTCPeerSession:
         self._username: str = ""
         self._pk_user: str = ""
         self._gek_challenge: bytes | None = None
+        # Same value as the GEK challenge, but kept for the life of the connection:
+        # a join_request is signed over it, and it must stay verifiable after the
+        # handshake clears the challenge (an operator pairs while already connected).
+        self._nonce_node: bytes = b""
+        self._join_attempts = 0
         self._nonce_client: bytes = b""
         self._admin_ops: dict[str, dict] = {}   # op_id → pending admin operation
         self._uploads: dict[str, dict] = {}   # filename → {next_index, bytes}
@@ -259,6 +278,12 @@ class WebRTCPeerSession:
                     asyncio.ensure_future(self._do_gek_bundle_fetch())
                 else:
                     asyncio.ensure_future(self._do_keypair_bundle_fetch())
+            elif mtype == MNP.JOIN_REQUEST and self._nonce_node:
+                # Valid both before the GEK proof (a new member has no GEK to prove
+                # with) and after it (an operator pairing a browser is already
+                # connected). Authority comes from the pairing code and the
+                # signature, never from the session state.
+                asyncio.ensure_future(self._do_join_request(msg))
             elif self._user_id is None:
                 self._send({"type": "error", "detail": "Handshake required"})
             elif mtype == MNP.INDEX_SYNC:
@@ -277,8 +302,8 @@ class WebRTCPeerSession:
                 self._do_file_delete(msg)
             elif mtype == MNP.ADMIN_RESPONSE:
                 self._do_admin_response(msg)
-            elif mtype == MNP.GEK_BUNDLE_STORE:
-                self._do_gek_bundle_store(msg)
+            elif mtype == MNP.INVITE_CREATE:
+                self._do_invite_create(msg)
             elif mtype == MNP.KEYPAIR_BUNDLE_STORE:
                 asyncio.ensure_future(self._do_keypair_bundle_store(msg))
             elif mtype == MNP.STREAM_REQUEST:
@@ -359,6 +384,7 @@ class WebRTCPeerSession:
             return
 
         self._gek_challenge = os.urandom(NONCE_LEN)
+        self._nonce_node = self._gek_challenge
         self._send({
             "type": MNP.HANDSHAKE_CHALLENGE,
             "v": MNP_VERSION,
@@ -472,49 +498,40 @@ class WebRTCPeerSession:
         else:
             self._send({"type": MNP.GEK_BUNDLE_RESP, "v": MNP_VERSION, "found": False})
 
-    def _do_gek_bundle_store(self, msg: dict) -> None:
+    def _do_invite_create(self, msg: dict) -> None:
         """
-        Request to store a wrapped GEK bundle for a target user.
-
-        Finding C5b: this used to write whatever any authenticated member sent, with
-        INSERT OR REPLACE semantics, and then auto-activate the bundle if it was
-        addressed to the node operator. Since the operator's X25519 public key is
-        public — the node even hands it out in handshake_ack — any member could wrap
-        a GEK of their own choosing for the operator and make the node adopt it,
-        locking every legitimate member out of the group and taking over the key.
+        Issue a one-time pairing code for someone the operator wants to admit.
 
-        Storing a bundle is now a node-operator operation gated by an Ed25519
-        challenge, and nothing arriving over MNP can activate a GEK: activation
-        happens only through the local admin UI or the CLI.
+        Replaces the old invite path, where the inviter fetched the invitee's
+        public key from the hub and wrapped the group key for whatever came back
+        (H3). The node now needs nothing but a name: it will wrap the key itself,
+        later, for a key the invitee proves they hold.
         """
-        bundle_store = self._ctx.get("bundle_store")
-        if not bundle_store:
-            self._send({"type": "error", "detail": "Bundle store not available"})
+        roster = self._ctx.get("roster")
+        if roster is None:
+            self._send({"type": "error", "detail": "Roster not available"})
             return
 
-        target_user_id = msg.get("user_id", "")
+        invitee_id = msg.get("user_id", "")
         group_id = msg.get("group_id") or self._group_id
-        pk_eph = msg.get("pk_eph_b64", "")
-        nonce = msg.get("nonce_b64", "")
-        wrapped = msg.get("wrapped_b64", "")
-
-        if not target_user_id or not pk_eph or not nonce or not wrapped or not group_id:
-            self._send({"type": "error", "detail": "Missing bundle fields"})
+        if not invitee_id or not group_id:
+            self._send({"type": "error", "detail": "Missing user_id or group_id"})
+            return
+        if group_id != self._group_id:
+            self._send({"type": "error", "detail": "Wrong group for this session"})
             return
 
-        if not self._ctx.get("admin_pk_ed25519"):
+        if not self._has_admin_authority():
             self._send({
                 "type": "error",
-                "detail": "No admin key pinned — bundle storage refused",
+                "detail": "No operator paired — run `meshbay-node operator pair`",
             })
             return
 
-        self._issue_admin_challenge(OP_GEK_BUNDLE_STORE, target_user_id, {
+        self._issue_admin_challenge(OP_INVITE_CREATE, invitee_id, {
             "group_id": group_id,
-            "user_id": target_user_id,
-            "pk_eph_b64": pk_eph,
-            "nonce_b64": nonce,
-            "wrapped_b64": wrapped,
+            "user_id": invitee_id,
+            "username": str(msg.get("username", ""))[:64],
         })
 
     async def _do_keypair_bundle_fetch(self) -> None:
@@ -560,6 +577,240 @@ class WebRTCPeerSession:
             "detail": "keypair_bundle_stored",
         })
 
+    # ── Pairing and join (H3, M3) ────────────────────────────────────────────
+
+    def _join_refuse(self, reason: str, audit_detail: str = "") -> None:
+        self._join_attempts += 1
+        # Node-wide window, shared across connections: reconnecting must not reset
+        # the budget.
+        now = time.time()
+        failures = [t for t in self._ctx.get("join_failures", [])
+                    if now - t < JOIN_FAILURE_WINDOW]
+        failures.append(now)
+        self._ctx["join_failures"] = failures
+        self._audit_join("join_refused", audit_detail or reason)
+        self._send({
+            "type": MNP.JOIN_RESULT,
+            "v": MNP_VERSION,
+            "ok": False,
+            "reason": reason,
+        })
+
+    def _audit_join(self, event: str, detail: str) -> None:
+        audit = self._ctx.get("audit_store")
+        if not audit:
+            return
+        self._remote_ip = self._remote_ip or _get_remote_ip(self._pc)
+        asyncio.ensure_future(audit.log_event(
+            user_id=self._user_id or getattr(self, "_pending_sub", "unknown"),
+            event=event,
+            ip=self._remote_ip,
+            username=self._username or getattr(self, "_pending_username", ""),
+            group_id=self._group_id or getattr(self, "_pending_group", "") or "",
+            detail=detail,
+        ))
+
+    async def _do_join_request(self, msg: dict) -> None:
+        """
+        Pin an identity, or recognise one already pinned.
+
+        The client signs its own Ed25519 and X25519 keys together with the node's
+        nonce, so the identity key vouches for the encryption key — that is what
+        will make it safe for the node to wrap the GEK for a key that arrived over
+        the wire instead of one fetched from the hub's directory (H3).
+
+        A first pairing needs a one-time code, which the hub never sees. Afterwards
+        the pin is the credential and a changed key is refused outright, the same
+        rule the client applies to `pk_node` (11.5.8).
+        """
+        roster = self._ctx.get("roster")
+        if roster is None:
+            self._send({"type": "error", "detail": "Roster not available"})
+            return
+
+        if self._join_attempts >= MAX_JOIN_ATTEMPTS:
+            self._send({"type": "error", "detail": "Too many attempts"})
+            return
+
+        now = time.time()
+        recent = [t for t in self._ctx.get("join_failures", [])
+                  if now - t < JOIN_FAILURE_WINDOW]
+        if len(recent) >= MAX_JOIN_FAILURES_WINDOW:
+            self._audit_join("join_throttled", f"{len(recent)} failures in window")
+            self._send({"type": "error", "detail": "Pairing temporarily locked"})
+            return
+
+        user_id = self._user_id or getattr(self, "_pending_sub", "")
+        username = self._username or getattr(self, "_pending_username", "")
+        if not user_id:
+            self._send({"type": "error", "detail": "Handshake required"})
+            return
+
+        pk_ed_b64 = msg.get("pk_ed25519", "")
+        pk_x_b64 = msg.get("pk_x25519", "")
+        code = msg.get("code", "")
+        ts = msg.get("ts", 0)
+
+        try:
+            pk_ed_raw = base64.b64decode(pk_ed_b64)
+            pk_x_raw = base64.b64decode(pk_x_b64)
+            if len(pk_ed_raw) != 32 or len(pk_x_raw) != 32:
+                raise ValueError
+            pk_ed = Ed25519PublicKey.from_public_bytes(pk_ed_raw)
+        except Exception:
+            self._join_refuse("invalid_keys")
+            return
+
+        if not isinstance(ts, int) or abs(time.time() - ts) > JOIN_TTL:
+            self._join_refuse("stale_request")
+            return
+
+        # An empty group_id means operator pairing, which is node-wide. Anything
+        # else must be the group this connection authenticated to — a signature
+        # obtained for one group must not name another.
+        group_id = msg.get("group_id", "") or ""
+        session_group = self._group_id or getattr(self, "_pending_group", "") or ""
+        if group_id and group_id != session_group:
+            self._join_refuse("group_mismatch")
+            return
+
+        transcript = join_transcript(
+            node_pk_b64=self._node_pk_b64(),
+            group_id=group_id,
+            user_id=user_id,
+            pk_ed25519_b64=pk_ed_b64,
+            pk_x25519_b64=pk_x_b64,
+            nonce_node=self._nonce_node,
+            ts=ts,
+        )
+        try:
+            sig = base64.b64decode(msg.get("sig", ""))
+        except Exception:
+            self._join_refuse("invalid_signature_encoding")
+            return
+        if not self._verify_sig(pk_ed, transcript, sig):
+            self._join_refuse("signature_invalid")
+            return
+
+        known = await roster.get_identity(user_id)
+        if known:
+            if known["pk_ed25519"] != pk_ed_b64 or known["pk_x25519"] != pk_x_b64:
+                # The blocking warning, raised where it matters: whoever this is
+                # holds a different key than the person the operator paired.
+                self._join_refuse(
+                    "key_changed",
+                    f"pinned={known['pk_ed25519'][:16]} presented={pk_ed_b64[:16]}")
+                return
+            member = await roster.get_member(group_id, user_id)
+            await self._join_ok(
+                user_id, pk_x_raw, session_group,
+                role=member["role"] if member else "",
+                recognised=True,
+            )
+            return
+
+        if not code:
+            if self._group_join_policy(session_group) == "open":
+                # An open-join group admits anyone the hub calls a member, so a
+                # code would protect nothing — the hub can walk in through the
+                # front door. Pin what turns up and say so in the audit log.
+                await self._pin_and_admit(
+                    roster, user_id, username, pk_ed_b64, pk_x_b64,
+                    group_id=session_group, role=ROLE_MEMBER,
+                    approved_by="open-join", via="tofu")
+                await self._join_ok(user_id, pk_x_raw, session_group,
+                                    role=ROLE_MEMBER, recognised=False)
+                return
+            self._join_refuse("code_required")
+            return
+
+        invite = await roster.consume_invite(code, user_id)
+        if not invite:
+            self._join_refuse("code_invalid")
+            return
+
+        await self._pin_and_admit(
+            roster, user_id, username, pk_ed_b64, pk_x_b64,
+            group_id=invite["group_id"], role=invite["role"],
+            approved_by=invite["created_by"], via="code")
+        await self._join_ok(user_id, pk_x_raw, invite["group_id"],
+                            role=invite["role"], recognised=False)
+
+    def _group_join_policy(self, group_id: str) -> str:
+        """
+        Admission policy for a group, read from the node's own configuration.
+
+        Never from the hub: a hub that could declare a group open would be handed
+        the key to it (§3.4 of docs/invite-pairing-v1.md).
+        """
+        gctx = (self._ctx.get("groups") or {}).get(group_id) or {}
+        return gctx.get("join_policy", "invite")
+
+    async def _pin_and_admit(
+        self, roster, user_id: str, username: str, pk_ed_b64: str, pk_x_b64: str,
+        *, group_id: str, role: str, approved_by: str, via: str,
+    ) -> None:
+        await roster.pin_identity(
+            user_id=user_id, username=username,
+            pk_ed25519=pk_ed_b64, pk_x25519=pk_x_b64, via=via,
+        )
+        await roster.set_member(
+            group_id=group_id, user_id=user_id, role=role,
+            status="active", approved_by=approved_by,
+        )
+        if role == ROLE_OPERATOR:
+            self._ctx["has_admin_authority"] = True
+
+        log.info("Identity pinned (%s): user=%s role=%s", via, user_id[:8], role)
+        self._audit_join("join_pinned", f"role={role} via={via}")
+
+    async def _join_ok(
+        self, user_id: str, pk_x_raw: bytes, group_id: str,
+        *, role: str, recognised: bool,
+    ) -> None:
+        """
+        Answer a join, wrapping the group key for the key the caller just proved.
+
+        This is the H3 fix. The inviter used to fetch the invitee's public key from
+        the hub and wrap the GEK for whatever came back, so a hub that answered
+        with its own key was handed the group key by an honest member following the
+        protocol exactly. The node now wraps for a key that arrived from its owner
+        over an authenticated channel, bound to a pinned identity.
+        """
+        reply = {
+            "type": MNP.JOIN_RESULT,
+            "v": MNP_VERSION,
+            "ok": True,
+            "recognised": recognised,
+            "role": role,
+        }
+
+        roster = self._ctx["roster"]
+        if group_id and not await roster.is_authorized(group_id, user_id):
+            # Pinned on this node, but not admitted to this group. Hub membership
+            # alone must not produce a key.
+            reply["gek"] = False
+            reply["reason"] = "not_authorized_for_group"
+            self._send(reply)
+            self._audit_join("join_no_gek", f"group={group_id[:8]} not authorized")
+            return
+
+        gctx = (self._ctx.get("groups") or {}).get(group_id) or {}
+        gek = gctx.get("gek")
+        if not gek:
+            reply["gek"] = False
+            reply["reason"] = "no_gek"
+            self._send(reply)
+            return
+
+        bundle = wrap_gek_aes(gek, pk_x_raw)
+        reply["gek"] = True
+        reply["pk_eph_b64"] = bundle["pk_eph_b64"]
+        reply["nonce_b64"] = bundle["nonce_b64"]
+        reply["wrapped_b64"] = bundle["wrapped_b64"]
+        self._send(reply)
+        self._audit_join("gek_wrapped", f"group={group_id[:8]}")
+
     def _audit_pre_proof_fetch(self, mtype: str) -> None:
         """Record bundle access made before the GEK proof (C4)."""
         audit = self._ctx.get("audit_store")
@@ -903,9 +1154,8 @@ class WebRTCPeerSession:
             self._send({"type": "error", "detail": "File not found"})
             return
 
-        admin_pk = self._ctx.get("admin_pk_ed25519")
         has_uploader_pk = bool(entry.uploader_pk)
-        if not admin_pk and not has_uploader_pk:
+        if not self._has_admin_authority() and not has_uploader_pk:
             self._send({"type": "error", "detail": "No authorized key for deletion"})
             return
 
@@ -956,6 +1206,43 @@ class WebRTCPeerSession:
         except Exception:
             return False
 
+    def _has_admin_authority(self) -> bool:
+        """
+        Cheap synchronous pre-check: is there anyone who could authorize this?
+
+        Only decides whether to issue a challenge at all — the gate is
+        `_verify_admin_sig`. The flag is set at startup and refreshed in-process
+        when an operator pairs.
+        """
+        return bool(self._ctx.get("admin_pk_ed25519")
+                    or self._ctx.get("has_admin_authority"))
+
+    async def _verify_admin_sig(self, transcript: bytes, sig: bytes) -> bool:
+        """
+        Check a signature against every key holding node-operator authority.
+
+        Read from the roster on each call rather than cached: revoking a paired
+        browser must take effect immediately, and admin operations are rare enough
+        that a SQLite read costs nothing. `admin_pk_ed25519` in node.toml is still
+        honoured so an existing deployment keeps working until its operator pairs
+        (M3) — it is the legacy form of the same statement.
+        """
+        legacy = self._ctx.get("admin_pk_ed25519")
+        if self._verify_sig(legacy, transcript, sig):
+            return True
+
+        roster = self._ctx.get("roster")
+        if roster is None:
+            return False
+        for pk_b64 in await roster.operator_pks():
+            try:
+                pk = Ed25519PublicKey.from_public_bytes(base64.b64decode(pk_b64))
+            except Exception:
+                continue
+            if self._verify_sig(pk, transcript, sig):
+                return True
+        return False
+
     def _do_admin_response(self, msg: dict) -> None:
         op_id = msg.get("op_id", "")
         sig_b64 = msg.get("signature", "")
@@ -985,14 +1272,15 @@ class WebRTCPeerSession:
         )
 
         if pending["op"] == OP_FILE_DELETE:
-            self._admin_exec_file_delete(pending, transcript, sig_bytes)
-        elif pending["op"] == OP_GEK_BUNDLE_STORE:
             asyncio.ensure_future(
-                self._admin_exec_bundle_store(pending, transcript, sig_bytes))
+                self._admin_exec_file_delete(pending, transcript, sig_bytes))
+        elif pending["op"] == OP_INVITE_CREATE:
+            asyncio.ensure_future(
+                self._admin_exec_invite_create(pending, transcript, sig_bytes))
         else:
             self._send({"type": "error", "detail": "Unknown admin operation"})
 
-    def _admin_exec_file_delete(
+    async def _admin_exec_file_delete(
         self, pending: dict, transcript: bytes, sig: bytes,
     ) -> None:
         file_id = pending["subject"]
@@ -1012,7 +1300,7 @@ class WebRTCPeerSession:
 
         # Node operator, or the user who uploaded this file — verified by the key
         # recorded at upload time, never by a JWT claim (the hub controls those).
-        if not (self._verify_sig(self._ctx.get("admin_pk_ed25519"), transcript, sig)
+        if not (await self._verify_admin_sig(transcript, sig)
                 or self._verify_sig(uploader_pk, transcript, sig)):
             self._send({"type": "error", "detail": "Signature verification failed"})
             self._audit("admin_auth_failed", f"file_delete:{file_id[:16]}")
@@ -1020,33 +1308,46 @@ class WebRTCPeerSession:
 
         self._exec_file_delete(ctx, file_id, entry)
 
-    async def _admin_exec_bundle_store(
+    async def _admin_exec_invite_create(
         self, pending: dict, transcript: bytes, sig: bytes,
     ) -> None:
         # Node operator only. A group admin who does not run the node has no
-        # authority over what this node stores (draft-v4 §4.2.x, deny by default).
-        if not self._verify_sig(self._ctx.get("admin_pk_ed25519"), transcript, sig):
+        # authority over who this node admits (deny by default). Delegation is
+        # designed but deferred — see §6.2 of docs/invite-pairing-v1.md.
+        if not await self._verify_admin_sig(transcript, sig):
             self._send({"type": "error", "detail": "Signature verification failed"})
-            self._audit("admin_auth_failed", f"gek_bundle_store:{pending['subject'][:16]}")
+            self._audit("admin_auth_failed", f"invite_create:{pending['subject'][:16]}")
             return
 
-        payload = pending["payload"]
-        bundle_store = self._ctx.get("bundle_store")
-        if not bundle_store:
-            self._send({"type": "error", "detail": "Bundle store not available"})
+        roster = self._ctx.get("roster")
+        if roster is None:
+            self._send({"type": "error", "detail": "Roster not available"})
             return
 
-        await bundle_store.store(
-            payload["group_id"], payload["user_id"],
-            payload["pk_eph_b64"], payload["nonce_b64"], payload["wrapped_b64"],
+        payload = pending["payload"]
+        code = await roster.create_invite(
+            group_id=payload["group_id"],
+            user_id=payload["user_id"],
+            role=ROLE_MEMBER,
+            created_by=self._user_id or "",
         )
-        log.info("GEK bundle stored: group=%s user=%s",
+        invites = await roster.list_invites()
+        expires = next(
+            (i["expires_at"] for i in invites
+             if i["user_id"] == payload["user_id"]
+             and i["group_id"] == payload["group_id"]), "")
+
+        log.info("Invite created: group=%s user=%s",
                  payload["group_id"][:8], payload["user_id"][:8])
-        self._audit("gek_bundle_store", f"target={payload['user_id'][:8]}")
+        self._audit("invite_create", f"target={payload['user_id'][:8]}")
+        # The code exists in the clear exactly here and in the operator's hands.
         self._send({
-            "type": "ack", "v": MNP_VERSION,
-            "detail": "gek_bundle_stored",
+            "type": MNP.INVITE_RESULT,
+            "v": MNP_VERSION,
+            "code": code,
+            "expires_at": expires,
             "user_id": payload["user_id"],
+            "username": payload.get("username", ""),
         })
 
     def _exec_file_delete(self, ctx: dict, file_id: str, entry) -> None:
diff --git a/packages/meshbay-node/src/meshbay_node/ui/app.py b/packages/meshbay-node/src/meshbay_node/ui/app.py
index 21e4445..e671b72 100644
--- a/packages/meshbay-node/src/meshbay_node/ui/app.py
+++ b/packages/meshbay-node/src/meshbay_node/ui/app.py
@@ -24,6 +24,7 @@ from fastapi.responses import HTMLResponse, JSONResponse
 
 from meshbay_node import __version__
 from meshbay_common.crypto import generate_gek, wrap_gek_aes
+from meshbay_common.join import ROLE_OPERATOR
 
 log = logging.getLogger(__name__)
 
@@ -217,11 +218,61 @@ def create_ui_app(state: dict) -> FastAPI:
             ],
         }
 
+    # ── Operator pairing (localhost only) ──────────────────────────────────
+
+    @app.post("/api/operator/pair")
+    async def operator_pair():
+        """
+        Issue a one-time code that pairs a browser as this node's operator.
+
+        The code is the whole point: it binds the operator's browser identity key
+        to their account without asking the hub, which is what stops a hub from
+        naming itself node administrator (M3, and the same substitution as H3).
+        It is returned once and stored only as a hash.
+        """
+        roster = state.get("roster")
+        user_id = state.get("node_user_id")
+        if not roster or not user_id:
+            return JSONResponse({"error": "Node not connected to hub yet"}, 503)
+
+        code = await roster.create_invite(
+            group_id="",                 # operator authority is node-wide
+            user_id=user_id,
+            role=ROLE_OPERATOR,
+            created_by="local-cli",
+        )
+        invites = await roster.list_invites()
+        expires = next((i["expires_at"] for i in invites
+                        if i["user_id"] == user_id and i["role"] == ROLE_OPERATOR), "")
+        return {"code": code, "expires_at": expires, "user_id": user_id}
+
+    @app.get("/api/roster")
+    async def api_roster():
+        roster = state.get("roster")
+        if not roster:
+            return {"identities": [], "members": [], "pending_invites": 0}
+        return {
+            "identities": await roster.list_identities(),
+            "members": await roster.list_members(),
+            "pending_invites": len(await roster.list_invites()),
+        }
+
     # ── GEK initialization (operator only, localhost) ──────────────────────
 
     @app.post("/api/groups/{group_id}/gek")
     async def init_gek(group_id: str):
-        """Generate GEK, wrap for all group members, store, and activate."""
+        """
+        Generate the group key and activate it.
+
+        It used to be wrapped here for every member, using public keys fetched from
+        the hub — which is H3 with the node as the victim instead of the inviter: a
+        hub answering with its own key was handed the group key by the node itself.
+
+        Nothing is pre-wrapped for members now. Each member's copy is produced when
+        they connect, for a key they proved they hold (`join_request`). Only the
+        node's own copy is stored, so the daemon can reload the key across restarts
+        without the operator's browser.
+        """
         groups_ctx = state.get("groups_ctx", {})
         if group_id not in groups_ctx:
             return JSONResponse({"error": "Group not hosted on this node"}, 404)
@@ -234,48 +285,15 @@ def create_ui_app(state: dict) -> FastAPI:
         if not bundle_store:
             return JSONResponse({"error": "Bundle store not available"}, 503)
 
-        await hub.ensure_fresh_token()
-        session = hub._session
-        members_resp = await hub._http.get(
-            f"/v1/groups/{group_id}/members",
-            headers=session.auth_headers,
-        )
-        if not members_resp.is_success:
-            return JSONResponse(
-                {"error": f"Failed to fetch members: {members_resp.status_code}"}, 502)
-        members = members_resp.json().get("members", [])
-        if not members:
-            return JSONResponse({"error": "No members in group"}, 400)
-
         existing_gek = groups_ctx[group_id].get("gek")
         gek = existing_gek or generate_gek()
+        errors: list[str] = []
 
-        wrapped_count = 0
-        errors = []
-        for member in members:
-            username = member["username"]
-            user_id = member["user_id"]
-            try:
-                pk_data = await hub.get_user_pubkeys(username)
-                pk_x_raw = base64.b64decode(pk_data["pk_x25519"])
-                bundle = wrap_gek_aes(gek, pk_x_raw)
-                await bundle_store.store(
-                    group_id, user_id,
-                    bundle["pk_eph_b64"], bundle["nonce_b64"], bundle["wrapped_b64"],
-                )
-                wrapped_count += 1
-                log.info("GEK wrapped for %s (%s)", username, user_id[:8])
-            except Exception as e:
-                errors.append(f"{username}: {e}")
-                log.warning("Failed to wrap GEK for %s: %s", username, e)
+        roster = state.get("roster")
+        authorized = len(await roster.list_members(group_id)) if roster else 0
 
-        if wrapped_count == 0:
-            return JSONResponse(
-                {"error": "Failed to wrap GEK for any member", "details": errors}, 500)
-
-        # Also store a copy wrapped for the node keystore X25519 key
-        # so the daemon can reload GEK on restart without the operator's browser keys
-        config = state.get("config")
+        # Store a copy wrapped for the node keystore X25519 key so the daemon can
+        # reload the GEK on restart without the operator's browser keys.
         node_user_id = hub._session.user_id if hub._session else None
         pk_x_node_raw = state.get("pk_x25519_raw")
         if pk_x_node_raw and node_user_id:
@@ -286,13 +304,14 @@ def create_ui_app(state: dict) -> FastAPI:
                     node_bundle["pk_eph_b64"], node_bundle["nonce_b64"],
                     node_bundle["wrapped_b64"],
                 )
-                log.info("GEK also wrapped for node keystore (daemon reload)")
+                log.info("GEK wrapped for node keystore (daemon reload)")
             except Exception as e:
+                errors.append(f"node keystore: {e}")
                 log.warning("Failed to wrap GEK for node keystore: %s", e)
 
         groups_ctx[group_id]["gek"] = gek
-        log.info("GEK initialized for group %s — wrapped for %d/%d members",
-                 group_id[:8], wrapped_count, len(members))
+        log.info("GEK initialized for group %s — %d authorized member(s) will "
+                 "receive it on connect", group_id[:8], authorized)
 
         webrtc = state.get("webrtc")
         if webrtc and "groups" in webrtc._ctx and group_id in webrtc._ctx["groups"]:
@@ -301,8 +320,7 @@ def create_ui_app(state: dict) -> FastAPI:
         return {
             "status": "ok",
             "group_id": group_id,
-            "wrapped_count": wrapped_count,
-            "total_members": len(members),
+            "authorized_members": authorized,
             "errors": errors,
         }
 
@@ -585,8 +603,8 @@ async function initGEK(groupId) {{
     const resp = await fetch('/api/groups/' + groupId + '/gek?t=' + TOKEN, {{ method: 'POST' }});
     const data = await resp.json();
     if (resp.ok) {{
-      if (status) status.textContent = 'GEK initialized — wrapped for '
-        + data.wrapped_count + '/' + data.total_members + ' members';
+      if (status) status.textContent = 'GEK initialized — '
+        + data.authorized_members + ' authorized member(s) get it on connect';
       if (status) status.style.color = '#22c55e';
       setTimeout(() => location.reload(), 2000);
     }} else {{