feat: Phase 7 — Node v2 (multi-group, Sender Keys, 0-RTT, chat, denylist)

Implements all 8 milestones (7.0-7.7):

- 7.0: JWT carries `groups` claim; node verifies group membership at
  MNP handshake (QUIC + TCP+TLS). Resolves security review C2.
- 7.1: QUIC 0-RTT session resumption via stored session tickets
  (17-21ms reconnect vs 47ms cold).
- 7.2: Hub→node WebSocket signaling for NAT punch coordination
  (`client_incoming`/`punch_ready`) + jti denylist push. Denylist
  class blocks revoked users/jtis at handshake.
- 7.3: Multi-group daemon — one QUIC port serves N groups with
  per-group GEK, shared_root, and index routing.
- 7.4: HLS streaming via QUIC (STREAM_SEGMENT message type, ffmpeg
  segment extraction).
- 7.5: Sender Keys protocol for group chat (Signal Groups approach).
  Each member has own sending chain key, HKDF chain ratchet, AES-256-GCM
  encryption, Ed25519 signing. Resolves security review C1.
- 7.6: Chat store (SQLite via aiosqlite), CHAT_MESSAGE MNP wire type
  with peer broadcast, web UI with WebSocket push.
- 7.7: Argon2id calibration CLI.

First security review included (first-review.md). 109 tests, demo-v3
validated against meshbay.org production hub.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

1 files changed, 169 insertions, 0 deletions

diff --git a/packages/meshbay-node/tests/test_multi_group.py b/packages/meshbay-node/tests/test_multi_group.py
new file mode 100644
index 0000000..9be8d47
--- /dev/null
+++ b/packages/meshbay-node/tests/test_multi_group.py
@@ -0,0 +1,169 @@
+"""
+Multi-group isolation test: two groups on one QUIC server.
+
+Verifies that:
+  - A user in group-a can fetch files from group-a
+  - A user in group-a is rejected when requesting group-b
+  - A user in both groups can access both
+"""
+
+import os
+import time
+import jwt
+import pytest
+from pathlib import Path
+from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
+from cryptography.hazmat.primitives import serialization
+
+from meshbay_common.crypto import generate_gek, pk_to_b64
+from meshbay_node.indexer import DirectoryIndexer, GroupIndex
+from meshbay_node.transport.quic_server import QuicChunkServer
+from meshbay_node.transport.quic_client import QuicChunkClient
+
+
+@pytest.fixture
+def sk_node():
+    return Ed25519PrivateKey.generate()
+
+@pytest.fixture
+def sk_hub():
+    return Ed25519PrivateKey.generate()
+
+@pytest.fixture
+def gek_a():
+    return generate_gek()
+
+@pytest.fixture
+def gek_b():
+    return generate_gek()
+
+@pytest.fixture
+def dir_a(tmp_path):
+    d = tmp_path / "group_a"
+    d.mkdir()
+    (d / "file_a.txt").write_bytes(b"content from group A " * 100)
+    return d
+
+@pytest.fixture
+def dir_b(tmp_path):
+    d = tmp_path / "group_b"
+    d.mkdir()
+    (d / "file_b.txt").write_bytes(b"content from group B " * 100)
+    return d
+
+
+def make_jwt(sk_hub, pk_node_b64, groups, user_id="user-001", ttl=3600):
+    sk_pem = sk_hub.private_bytes(
+        serialization.Encoding.PEM,
+        serialization.PrivateFormat.PKCS8,
+        serialization.NoEncryption(),
+    )
+    now = int(time.time())
+    return jwt.encode({
+        "iss": "test-hub", "sub": user_id,
+        "pk_user": pk_node_b64, "hub_id": "test-hub",
+        "jti": "test-jti", "iat": now, "exp": now + ttl,
+        "groups": groups,
+    }, sk_pem, algorithm="EdDSA")
+
+
+@pytest.fixture
+async def multi_group_server(sk_node, sk_hub, gek_a, gek_b, dir_a, dir_b, tmp_path):
+    hub_pk_pem = sk_hub.public_key().public_bytes(
+        serialization.Encoding.PEM, serialization.PublicFormat.SubjectPublicKeyInfo)
+
+    indexer_a = DirectoryIndexer(root=dir_a, group_id="group-a", sk_node=sk_node, gek=gek_a)
+    await indexer_a.initial_scan()
+
+    indexer_b = DirectoryIndexer(root=dir_b, group_id="group-b", sk_node=sk_node, gek=gek_b)
+    await indexer_b.initial_scan()
+
+    groups = {
+        "group-a": {"gek": gek_a, "shared_root": dir_a, "index": indexer_a.index},
+        "group-b": {"gek": gek_b, "shared_root": dir_b, "index": indexer_b.index},
+    }
+
+    cert_path = tmp_path / "node.crt"
+    key_path  = tmp_path / "node.key"
+
+    server = QuicChunkServer(
+        sk_node=sk_node, hub_pk_pem=hub_pk_pem,
+        gek=gek_a, shared_root=dir_a, index=indexer_a.index,
+        host="127.0.0.1", port=19200,
+        cert_path=cert_path, key_path=key_path,
+        groups=groups,
+    )
+    await server.start()
+    yield server, indexer_a, indexer_b
+    await server.stop()
+
+
+@pytest.mark.asyncio
+async def test_user_can_access_own_group(
+    multi_group_server, sk_node, sk_hub, gek_a,
+):
+    """User in group-a can fetch index and chunks from group-a."""
+    server, indexer_a, _ = multi_group_server
+    token = make_jwt(sk_hub, pk_to_b64(sk_node.public_key()), groups=["group-a"])
+
+    async with QuicChunkClient(
+        host="127.0.0.1", port=19200,
+        jwt_token=token, gek=gek_a,
+        pk_node_b64=pk_to_b64(sk_node.public_key()),
+        group_id="group-a",
+    ) as client:
+        wire = await client.fetch_index()
+        recovered = GroupIndex.deserialize(wire, sk_node=sk_node, gek=gek_a)
+        assert recovered.count == 1
+
+        entry = recovered.entries[0]
+        assert entry.name == "file_a.txt"
+        chunk = await client.fetch_chunk(entry.id, chunk_index=0)
+        assert chunk == b"content from group A " * 100
+
+
+@pytest.mark.asyncio
+async def test_user_rejected_from_other_group(
+    multi_group_server, sk_node, sk_hub, gek_b,
+):
+    """User in group-a only is rejected when requesting group-b."""
+    server, _, _ = multi_group_server
+    token = make_jwt(sk_hub, pk_to_b64(sk_node.public_key()), groups=["group-a"])
+
+    with pytest.raises(ConnectionError, match="rejected"):
+        async with QuicChunkClient(
+            host="127.0.0.1", port=19200,
+            jwt_token=token, gek=gek_b,
+            pk_node_b64=pk_to_b64(sk_node.public_key()),
+            group_id="group-b",
+        ) as client:
+            await client.fetch_index()
+
+
+@pytest.mark.asyncio
+async def test_dual_group_user_accesses_both(
+    multi_group_server, sk_node, sk_hub, gek_a, gek_b,
+):
+    """User in both groups can access either group's files."""
+    server, indexer_a, indexer_b = multi_group_server
+    token = make_jwt(sk_hub, pk_to_b64(sk_node.public_key()), groups=["group-a", "group-b"])
+
+    async with QuicChunkClient(
+        host="127.0.0.1", port=19200,
+        jwt_token=token, gek=gek_a,
+        pk_node_b64=pk_to_b64(sk_node.public_key()),
+        group_id="group-a",
+    ) as client_a:
+        wire_a = await client_a.fetch_index()
+        idx_a = GroupIndex.deserialize(wire_a, sk_node=sk_node, gek=gek_a)
+        assert idx_a.entries[0].name == "file_a.txt"
+
+    async with QuicChunkClient(
+        host="127.0.0.1", port=19200,
+        jwt_token=token, gek=gek_b,
+        pk_node_b64=pk_to_b64(sk_node.public_key()),
+        group_id="group-b",
+    ) as client_b:
+        wire_b = await client_b.fetch_index()
+        idx_b = GroupIndex.deserialize(wire_b, sk_node=sk_node, gek=gek_b)
+        assert idx_b.entries[0].name == "file_b.txt"