fix: continue recovered streams in a new segment

maintainer edit: streamed timeout recovery was returning the retried response internally while the channel still treated the final outbound as already streamed. End the current stream segment before retry/fallback recovery so subsequent deltas are delivered in a new segment.

tests/providers/test_provider_retry.py

@@ -199,6 +199,49 @@ async def test_chat_stream_with_retry_retries_timeout_after_emitting_content(mon
     assert provider.last_kwargs.get("on_content_delta") is None
 
 
+@pytest.mark.asyncio
+async def test_chat_stream_with_retry_retries_timeout_in_new_stream_segment(
+    monkeypatch,
+) -> None:
+    first = LLMResponse(
+        content="Error calling LLM: stream stalled for more than 30 seconds",
+        finish_reason="error",
+        error_kind="timeout",
+    )
+    first._test_stream_delta = "partial"  # type: ignore[attr-defined]
+    second = LLMResponse(content="full retry response")
+    second._test_stream_delta = "full retry response"  # type: ignore[attr-defined]
+    provider = ScriptedProvider([first, second])
+    deltas: list[str] = []
+    recoveries: list[str] = []
+    delays: list[int] = []
+
+    async def _fake_sleep(delay: int) -> None:
+        delays.append(delay)
+
+    async def _on_delta(delta: str) -> None:
+        deltas.append(delta)
+
+    async def _on_stream_recover() -> None:
+        recoveries.append("recover")
+
+    monkeypatch.setattr("nanobot.providers.base.asyncio.sleep", _fake_sleep)
+
+    response = await provider.chat_stream_with_retry(
+        messages=[{"role": "user", "content": "hello"}],
+        on_content_delta=_on_delta,
+        on_stream_recover=_on_stream_recover,
+    )
+
+    assert response.content == "full retry response"
+    assert response.finish_reason == "stop"
+    assert provider.calls == 2
+    assert deltas == ["partial", "full retry response"]
+    assert recoveries == ["recover"]
+    assert delays == [1]
+    assert provider.last_kwargs.get("on_content_delta") is not None
+
+
 @pytest.mark.asyncio
 async def test_chat_with_retry_uses_provider_generation_defaults() -> None:
     """When callers omit generation params, provider.generation defaults are used."""