code-review fixes: fsync, entropy, is_dm propagation, tests

- Add os.fsync with Windows-compatible directory flush in pairing store
- Increase pairing code length from 6 -> 8 characters for higher entropy
- Remove SystemExit on empty allowFrom; empty list now defers to pairing
- Update is_allowed docstring to document pairing fallback semantics
- Propagate is_dm to Matrix (direct rooms) and Slack (im channels)
- Slack _is_allowed now checks pairing store for DM allowlist mode
- Fix /pairing revoke to accept optional channel argument
- Move inline import time to module top-level
- Add WebSocket comment explaining is_dm=True assumption
- Add comprehensive tests for store and BaseChannel pairing integration
- Fix existing tests that expected empty allowFrom to hard-exit

Refs #3774

nanobot/channels/base.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import time
 from abc import ABC, abstractmethod
 from pathlib import Path
 from typing import Any
@@ -191,6 +192,10 @@ class BaseChannel(ABC):
         2. ``allowFrom`` list → allow if sender_id is present.
         3. Pairing store approved list → allow if previously approved.
         4. Otherwise deny.
+
+        An empty ``allowFrom`` list does not cause a hard exit; instead it
+        defers to the pairing store so that unknown DM senders can request
+        access via a pairing code.
         """
         if isinstance(self.config, dict):
             if "allow_from" in self.config:
@@ -296,8 +301,6 @@ class BaseChannel(ABC):
                 reply = "No pending pairing requests."
             else:
                 lines = ["Pending pairing requests:"]
-                import time
-
                 for item in pending:
                     remaining = int(item.get("expires_at", 0) - time.time())
                     expiry = f"{remaining}s" if remaining > 0 else "expired"
@@ -331,12 +334,14 @@ class BaseChannel(ABC):
 
         elif sub == "revoke":
             if arg is None:
-                reply = "Usage: `/pairing revoke <user_id>`"
+                reply = "Usage: `/pairing revoke <user_id>` or `/pairing revoke <channel> <user_id>`"
             else:
-                if revoke(self.name, arg):
-                    reply = f"Revoked {arg} from {self.name}"
+                target_channel = parts[3] if len(parts) > 3 else self.name
+                target_user = arg if len(parts) <= 3 else parts[3]
+                if revoke(target_channel, target_user):
+                    reply = f"Revoked {target_user} from {target_channel}"
                 else:
-                    reply = f"{arg} was not in the approved list for {self.name}"
+                    reply = f"{target_user} was not in the approved list for {target_channel}"
 
         else:
             reply = (

nanobot/channels/manager.py

@@ -143,9 +143,9 @@ class ChannelManager:
                     allow = cfg.get("allowFrom")
             else:
                 allow = getattr(cfg, "allow_from", None)
-            if allow == []:
+            if allow is None:
                 raise SystemExit(
-                    f'Error: "{name}" has empty allowFrom (denies all). '
+                    f'Error: "{name}" is missing allowFrom. '
                     f'Set ["*"] to allow everyone, or add specific user IDs.'
                 )
 

nanobot/channels/matrix.py

@@ -28,9 +28,10 @@ try:
         RoomMessageMedia,
         RoomMessageText,
         RoomSendError,
+        RoomSendResponse,
         RoomTypingError,
         SyncError,
-        UploadError, RoomSendResponse,
+        UploadError,
     )
     from nio.crypto.attachments import decrypt_attachment
     from nio.exceptions import EncryptionError
@@ -870,6 +871,7 @@ class MatrixChannel(BaseChannel):
             await self._handle_message(
                 sender_id=event.sender, chat_id=room.room_id,
                 content=event.body, metadata=self._base_metadata(room, event),
+                is_dm=self._is_direct_room(room),
             )
         except Exception:
             await self._stop_typing_keepalive(room.room_id, clear_typing=True)
@@ -907,6 +909,7 @@ class MatrixChannel(BaseChannel):
                 content="\n".join(parts),
                 media=[attachment["path"]] if attachment else [],
                 metadata=meta,
+                is_dm=self._is_direct_room(room),
             )
         except Exception:
             await self._stop_typing_keepalive(room.room_id, clear_typing=True)

nanobot/channels/slack.py

@@ -342,6 +342,22 @@ class SlackChannel(BaseChannel):
         channel_type = event.get("channel_type") or ""
 
         if not self._is_allowed(sender_id, chat_id, channel_type):
+            if channel_type == "im" and self.config.dm.enabled:
+                from nanobot.pairing import generate_code
+                code = generate_code(self.name, sender_id)
+                reply = (
+                    "This assistant requires approval before it can respond.\n"
+                    f"Your pairing code is: `{code}`\n"
+                    f"Ask the owner to run: `nanobot pairing approve {code}`"
+                )
+                await self.send(
+                    OutboundMessage(
+                        channel=self.name,
+                        chat_id=chat_id,
+                        content=reply,
+                        metadata={"_pairing_code": code},
+                    )
+                )
             return
 
         if channel_type != "im" and not self._should_respond_in_channel(event_type, text, chat_id):
@@ -608,11 +624,13 @@ class SlackChannel(BaseChannel):
                 self.logger.debug("done reaction failed: {}", e)
 
     def _is_allowed(self, sender_id: str, chat_id: str, channel_type: str) -> bool:
+        from nanobot.pairing import is_approved
+
         if channel_type == "im":
             if not self.config.dm.enabled:
                 return False
             if self.config.dm.policy == "allowlist":
-                return sender_id in self.config.dm.allow_from
+                return sender_id in self.config.dm.allow_from or is_approved(self.name, sender_id)
             return True
 
         # Group / channel messages

nanobot/channels/websocket.py

@@ -1249,6 +1249,8 @@ class WebSocketChannel(BaseChannel):
                 content = _parse_inbound_payload(raw)
                 if content is None:
                     continue
+                # WebSocket connections are always treated as 1:1 (DM) because
+                # each connection represents a single client browser/tab.
                 await self._handle_message(
                     sender_id=client_id,
                     chat_id=default_chat_id,

nanobot/pairing/store.py

@@ -8,6 +8,7 @@ private-assistant scale: small JSON file, simple locking, no external DB.
 from __future__ import annotations
 
 import json
+import os
 import secrets
 import string
 import threading
@@ -20,8 +21,9 @@ from loguru import logger
 from nanobot.config.paths import get_data_dir
 
 _LOCK = threading.Lock()
+
 _ALPHABET = string.ascii_uppercase + string.digits
-_CODE_LENGTH = 6  # e.g. XK9-42F
+_CODE_LENGTH = 8  # e.g. XK9-42F-MP
 _TTL_DEFAULT_S = 600  # 10 minutes
 
 
@@ -48,7 +50,17 @@ def _save(data: dict[str, Any]) -> None:
     with open(tmp, "w", encoding="utf-8") as f:
         json.dump(data, f, indent=2, ensure_ascii=False)
         f.flush()
+        os.fsync(f.fileno())
     tmp.replace(path)
+    # Ensure directory entry is flushed for durability (Unix only; no-op on Windows)
+    try:
+        fd = os.open(path.parent, os.O_RDONLY)
+        try:
+            os.fsync(fd)
+        finally:
+            os.close(fd)
+    except (OSError, NotImplementedError):
+        pass
 
 
 def _gc_pending(data: dict[str, Any]) -> None:
@@ -75,7 +87,7 @@ def generate_code(
         # Ensure uniqueness
         for _ in range(100):
             raw = "".join(secrets.choice(_ALPHABET) for _ in range(_CODE_LENGTH))
-            code = f"{raw[:3]}-{raw[3:]}"
+            code = f"{raw[:4]}-{raw[4:]}"
             if code not in data.get("pending", {}):
                 break
         else:  # pragma: no cover

tests/channels/test_base_channel.py

@@ -1,5 +1,7 @@
 from types import SimpleNamespace
 
+import pytest
+
 from nanobot.bus.events import OutboundMessage
 from nanobot.bus.queue import MessageBus
 from nanobot.channels.base import BaseChannel
@@ -7,6 +9,11 @@ from nanobot.channels.base import BaseChannel
 
 class _DummyChannel(BaseChannel):
     name = "dummy"
+    _sent: list[OutboundMessage]
+
+    def __init__(self, config, bus):
+        super().__init__(config, bus)
+        self._sent = []
 
     async def start(self) -> None:
         return None
@@ -15,7 +22,7 @@ class _DummyChannel(BaseChannel):
         return None
 
     async def send(self, msg: OutboundMessage) -> None:
-        return None
+        self._sent.append(msg)
 
 
 def test_is_allowed_requires_exact_match() -> None:
@@ -35,3 +42,94 @@ def test_is_allowed_denies_empty_dict_allow_from() -> None:
     channel = _DummyChannel({"allow_from": []}, MessageBus())
 
     assert channel.is_allowed("alice") is False
+
+
+def test_is_allowed_star_allows_all() -> None:
+    channel = _DummyChannel({"allowFrom": ["*"]}, MessageBus())
+    assert channel.is_allowed("anyone") is True
+
+
+def test_is_allowed_pairing_fallback(monkeypatch) -> None:
+    channel = _DummyChannel({"allowFrom": []}, MessageBus())
+    monkeypatch.setattr(
+        "nanobot.channels.base.is_approved", lambda _ch, sid: sid == "paired"
+    )
+    assert channel.is_allowed("paired") is True
+    assert channel.is_allowed("unknown") is False
+
+
+@pytest.mark.asyncio
+async def test_handle_message_dm_sends_pairing_code(monkeypatch) -> None:
+    channel = _DummyChannel({"allowFrom": []}, MessageBus())
+    monkeypatch.setattr(
+        "nanobot.channels.base.generate_code", lambda _ch, sid: "ABCD-EFGH"
+    )
+
+    await channel._handle_message(
+        sender_id="stranger", chat_id="chat1", content="hello", is_dm=True
+    )
+
+    assert len(channel._sent) == 1
+    msg = channel._sent[0]
+    assert "ABCD-EFGH" in msg.content
+    assert msg.metadata.get("_pairing_code") == "ABCD-EFGH"
+
+
+@pytest.mark.asyncio
+async def test_handle_message_group_ignores_unknown() -> None:
+    channel = _DummyChannel({"allowFrom": []}, MessageBus())
+
+    await channel._handle_message(
+        sender_id="stranger", chat_id="chat1", content="hello", is_dm=False
+    )
+
+    assert channel._sent == []
+
+
+@pytest.mark.asyncio
+async def test_handle_pairing_command_list(monkeypatch) -> None:
+    channel = _DummyChannel({"allowFrom": ["owner"]}, MessageBus())
+    monkeypatch.setattr(
+        "nanobot.channels.base.list_pending",
+        lambda: [
+            {
+                "code": "ABCD-EFGH",
+                "channel": "dummy",
+                "sender_id": "123",
+                "expires_at": 9999999999,
+            }
+        ],
+    )
+
+    await channel._handle_pairing_command("owner", "chat1", "/pairing list")
+
+    assert len(channel._sent) == 1
+    assert "ABCD-EFGH" in channel._sent[0].content
+
+
+@pytest.mark.asyncio
+async def test_handle_pairing_command_approve(monkeypatch) -> None:
+    channel = _DummyChannel({"allowFrom": ["owner"]}, MessageBus())
+    monkeypatch.setattr(
+        "nanobot.channels.base.approve_code",
+        lambda code: ("dummy", "123") if code == "ABCD-EFGH" else None,
+    )
+
+    await channel._handle_pairing_command("owner", "chat1", "/pairing approve ABCD-EFGH")
+
+    assert len(channel._sent) == 1
+    assert "Approved" in channel._sent[0].content
+
+
+@pytest.mark.asyncio
+async def test_handle_pairing_command_revoke(monkeypatch) -> None:
+    channel = _DummyChannel({"allowFrom": ["owner"]}, MessageBus())
+    monkeypatch.setattr(
+        "nanobot.channels.base.revoke",
+        lambda ch, sid: sid == "123",
+    )
+
+    await channel._handle_pairing_command("owner", "chat1", "/pairing revoke 123")
+
+    assert len(channel._sent) == 1
+    assert "Revoked" in channel._sent[0].content

tests/channels/test_channel_plugins.py

@@ -961,8 +961,8 @@ class _StartableChannel(BaseChannel):
 
 
 @pytest.mark.asyncio
-async def test_validate_allow_from_raises_on_empty_list():
-    """_validate_allow_from should raise SystemExit when allow_from is empty list."""
+async def test_validate_allow_from_allows_empty_list():
+    """Empty allow_from is valid now — pairing store handles unapproved senders."""
     fake_config = SimpleNamespace(
         channels=ChannelsConfig(),
         providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
@@ -973,11 +973,9 @@ async def test_validate_allow_from_raises_on_empty_list():
     mgr.channels = {"test": _ChannelWithAllowFrom(fake_config, None, [])}
     mgr._dispatch_task = None
 
-    with pytest.raises(SystemExit) as exc_info:
+    # Should not raise — empty list defers to pairing store
     mgr._validate_allow_from()
 
-    assert "empty allowFrom" in str(exc_info.value)
-
 
 @pytest.mark.asyncio
 async def test_validate_allow_from_passes_with_asterisk():
@@ -997,8 +995,8 @@ async def test_validate_allow_from_passes_with_asterisk():
 
 
 @pytest.mark.asyncio
-async def test_validate_allow_from_raises_on_empty_dict_allow_from():
-    """_validate_allow_from should reject empty dict-backed allow_from lists."""
+async def test_validate_allow_from_allows_empty_dict_allow_from():
+    """Empty dict-backed allow_from is valid — pairing store handles approval."""
     fake_config = SimpleNamespace(
         channels=ChannelsConfig(),
         providers=SimpleNamespace(groq=SimpleNamespace(api_key="")),
@@ -1009,11 +1007,8 @@ async def test_validate_allow_from_raises_on_empty_dict_allow_from():
     mgr.channels = {"test": _ChannelWithAllowFrom({"enabled": True}, None, [])}
     mgr._dispatch_task = None
 
-    with pytest.raises(SystemExit) as exc_info:
     mgr._validate_allow_from()
 
-    assert "empty allowFrom" in str(exc_info.value)
-
 
 @pytest.mark.asyncio
 async def test_get_channel_returns_channel_if_exists():

tests/pairing/test_store.py

@@ -0,0 +1,99 @@
+import time
+
+import pytest
+
+from nanobot.pairing import store
+
+
+@pytest.fixture(autouse=True)
+def _tmp_store(tmp_path, monkeypatch):
+    path = tmp_path / "pairing.json"
+    monkeypatch.setattr(store, "_store_path", lambda: path)
+
+
+class TestGenerateCode:
+    def test_format(self) -> None:
+        code = store.generate_code("telegram", "123")
+        assert len(code) == 9  # 4 + 1 + 4
+        assert code[4] == "-"
+        assert code.replace("-", "").isalnum()
+        assert code.replace("-", "").isupper()
+
+    def test_uniqueness(self) -> None:
+        codes = {store.generate_code("telegram", str(i)) for i in range(20)}
+        assert len(codes) == 20
+
+    def test_ttl_expiration(self) -> None:
+        code = store.generate_code("telegram", "123", ttl=1)
+        assert store.approve_code(code) is not None
+
+        code2 = store.generate_code("telegram", "456", ttl=0)
+        time.sleep(0.1)
+        assert store.approve_code(code2) is None
+
+
+class TestApproveDeny:
+    def test_approve_moves_to_approved(self) -> None:
+        code = store.generate_code("telegram", "123")
+        assert store.is_approved("telegram", "123") is False
+
+        result = store.approve_code(code)
+        assert result == ("telegram", "123")
+        assert store.is_approved("telegram", "123") is True
+        assert store.get_approved("telegram") == ["123"]
+
+    def test_deny_removes_pending(self) -> None:
+        code = store.generate_code("telegram", "123")
+        assert store.deny_code(code) is True
+        assert store.approve_code(code) is None
+
+    def test_deny_unknown_returns_false(self) -> None:
+        assert store.deny_code("UNKNOWN") is False
+
+    def test_approve_expired_returns_none(self) -> None:
+        code = store.generate_code("telegram", "123", ttl=0)
+        time.sleep(0.1)
+        assert store.approve_code(code) is None
+
+
+class TestRevoke:
+    def test_revoke_removes_sender(self) -> None:
+        code = store.generate_code("telegram", "123")
+        store.approve_code(code)
+        assert store.is_approved("telegram", "123") is True
+
+        assert store.revoke("telegram", "123") is True
+        assert store.is_approved("telegram", "123") is False
+        assert store.get_approved("telegram") == []
+
+    def test_revoke_unknown_returns_false(self) -> None:
+        assert store.revoke("telegram", "999") is False
+
+
+class TestListPending:
+    def test_empty(self) -> None:
+        assert store.list_pending() == []
+
+    def test_shows_pending(self) -> None:
+        store.generate_code("telegram", "123")
+        store.generate_code("discord", "456")
+        pending = store.list_pending()
+        assert len(pending) == 2
+        channels = {p["channel"] for p in pending}
+        assert channels == {"telegram", "discord"}
+
+    def test_expired_not_listed(self) -> None:
+        store.generate_code("telegram", "123", ttl=0)
+        time.sleep(0.1)
+        assert store.list_pending() == []
+
+
+class TestStoreDurability:
+    def test_corruption_recovery(self, tmp_path, monkeypatch) -> None:
+        path = tmp_path / "pairing.json"
+        path.write_text("not json{", encoding="utf-8")
+        monkeypatch.setattr(store, "_store_path", lambda: path)
+
+        # Should recover gracefully and act as empty store
+        assert store.list_pending() == []
+        assert store.is_approved("telegram", "123") is False