fix(discord): enable streaming replies

tests/channels/test_discord_channel.py

@@ -71,11 +71,25 @@ class _FakePartialMessage:
         self.id = message_id
 
 
+class _FakeSentMessage:
+    # Sent-message double supporting edit() for streaming tests.
+    def __init__(self, channel, content: str) -> None:
+        self.channel = channel
+        self.content = content
+        self.edits: list[dict] = []
+
+    async def edit(self, **kwargs) -> None:
+        self.edits.append(dict(kwargs))
+        if "content" in kwargs:
+            self.content = kwargs["content"]
+
+
 class _FakeChannel:
     # Channel double that records outbound payloads and typing activity.
     def __init__(self, channel_id: int = 123) -> None:
         self.id = channel_id
         self.sent_payloads: list[dict] = []
+        self.sent_messages: list[_FakeSentMessage] = []
         self.trigger_typing_calls = 0
         self.typing_enter_hook = None
 
@@ -85,6 +99,9 @@ class _FakeChannel:
             payload["file_name"] = payload["file"].filename
             del payload["file"]
         self.sent_payloads.append(payload)
+        message = _FakeSentMessage(self, payload.get("content", ""))
+        self.sent_messages.append(message)
+        return message
 
     def get_partial_message(self, message_id: int) -> _FakePartialMessage:
         return _FakePartialMessage(message_id)
@@ -427,6 +444,33 @@ async def test_send_fetches_channel_when_not_cached() -> None:
     assert target.sent_payloads == [{"content": "hello"}]
 
 
+def test_supports_streaming_enabled_by_default() -> None:
+    channel = DiscordChannel(DiscordConfig(enabled=True, allow_from=["*"]), MessageBus())
+
+    assert channel.supports_streaming is True
+
+
+@pytest.mark.asyncio
+async def test_send_delta_streams_by_editing_message(monkeypatch) -> None:
+    owner = DiscordChannel(DiscordConfig(enabled=True, allow_from=["*"]), MessageBus())
+    client = _FakeDiscordClient(owner, intents=None)
+    owner._client = client
+    owner._running = True
+    target = _FakeChannel(channel_id=123)
+    client.channels[123] = target
+
+    times = iter([1.0, 3.0, 5.0])
+    monkeypatch.setattr("nanobot.channels.discord.time.monotonic", lambda: next(times, 5.0))
+
+    await owner.send_delta("123", "hel", {"_stream_delta": True, "_stream_id": "s1"})
+    await owner.send_delta("123", "lo", {"_stream_delta": True, "_stream_id": "s1"})
+    await owner.send_delta("123", "", {"_stream_end": True, "_stream_id": "s1"})
+
+    assert target.sent_payloads[0] == {"content": "hel"}
+    assert target.sent_messages[0].edits == [{"content": "hello"}, {"content": "hello"}]
+    assert owner._stream_bufs == {}
+
+
 @pytest.mark.asyncio
 async def test_slash_new_forwards_when_user_is_allowlisted() -> None:
     channel = DiscordChannel(DiscordConfig(enabled=True, allow_from=["123"]), MessageBus())