refactor(reasoning): unify reasoning extraction across providers

Reasoning surfacing was split across three branches in runner.py plus
two separate streaming buffers (loop hook and runner progress stream),
with three independent display-side gates in the CLI. This collapsed
the policy into one source of truth and fixed two real bugs:

- Structured `reasoning_content` was suppressed whenever the answer was
  streamed, because the runner gated emission on `streamed_content`.
  Providers don't stream `reasoning_content`; it only arrives on the
  final response, so the answer stream and the reasoning channel are
  independent. Added `streamed_reasoning` to `AgentHookContext` to track
  the right bit.
- `channels.showReasoning` was subordinated to `sendProgress`. They are
  orthogonal — turning off progress streaming shouldn't silence
  reasoning. Reworked the CLI gates accordingly.

Single-helper consolidation:

- `extract_reasoning(reasoning_content, thinking_blocks, content)`
  returns `(reasoning_text, cleaned_content)` with a defined fallback
  order: dedicated field → Anthropic thinking_blocks → inline
  `<think>`/`<thought>` tags. Models that expose none of these
  short-circuit to `(None, content)` — zero overhead.
- `IncrementalThinkExtractor` replaces the ad-hoc `emit_incremental_think`
  function and its hand-rolled "emitted cursor" state in both the loop
  hook and the runner progress stream.

Also documented the new `showReasoning` channel option in
docs/configuration.md and noted its independence from sendProgress.

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/agent/test_runner.py

@@ -227,6 +227,111 @@ async def test_runner_prefers_reasoning_content_over_inline_think():
     assert emitted_reasoning[0] == "dedicated reasoning field"
 
 
+@pytest.mark.asyncio
+async def test_runner_emits_reasoning_content_even_when_answer_was_streamed():
+    """`reasoning_content` arrives only on the final response; streaming the
+    answer must not suppress it (the answer stream and the reasoning channel
+    are independent — only the reasoning-already-emitted bit matters)."""
+    from nanobot.agent.hook import AgentHook, AgentHookContext
+    from nanobot.agent.runner import AgentRunSpec, AgentRunner
+
+    provider = MagicMock()
+    provider.supports_progress_deltas = True
+    emitted_reasoning: list[str] = []
+
+    async def chat_stream_with_retry(*, on_content_delta=None, **kwargs):
+        if on_content_delta:
+            await on_content_delta("The ")
+            await on_content_delta("answer.")
+        return LLMResponse(
+            content="The answer.",
+            reasoning_content="step-by-step deduction",
+            tool_calls=[],
+            usage={"prompt_tokens": 5, "completion_tokens": 3},
+        )
+
+    provider.chat_stream_with_retry = chat_stream_with_retry
+    tools = MagicMock()
+    tools.get_definitions.return_value = []
+
+    class ReasoningHook(AgentHook):
+        async def emit_reasoning(self, reasoning_content: str | None) -> None:
+            if reasoning_content:
+                emitted_reasoning.append(reasoning_content)
+
+    progress_calls: list[str] = []
+
+    async def _progress(content: str, **_kwargs):
+        progress_calls.append(content)
+
+    runner = AgentRunner(provider)
+    result = await runner.run(AgentRunSpec(
+        initial_messages=[{"role": "user", "content": "question"}],
+        tools=tools,
+        model="test-model",
+        max_iterations=3,
+        max_tool_result_chars=_MAX_TOOL_RESULT_CHARS,
+        hook=ReasoningHook(),
+        stream_progress_deltas=True,
+        progress_callback=_progress,
+    ))
+
+    assert result.final_content == "The answer."
+    # The answer must have streamed AND the dedicated reasoning_content must
+    # have been emitted exactly once after the stream completed.
+    assert progress_calls, "answer should have streamed via progress callback"
+    assert emitted_reasoning == ["step-by-step deduction"]
+
+
+@pytest.mark.asyncio
+async def test_runner_does_not_double_emit_when_inline_think_already_streamed():
+    """Inline `<think>` blocks streamed incrementally during the answer
+    stream must not be re-emitted from the final response."""
+    from nanobot.agent.hook import AgentHook, AgentHookContext
+    from nanobot.agent.runner import AgentRunSpec, AgentRunner
+
+    provider = MagicMock()
+    provider.supports_progress_deltas = True
+    emitted_reasoning: list[str] = []
+
+    async def chat_stream_with_retry(*, on_content_delta=None, **kwargs):
+        if on_content_delta:
+            await on_content_delta("<think>working...</think>")
+            await on_content_delta("The answer.")
+        return LLMResponse(
+            content="<think>working...</think>The answer.",
+            tool_calls=[],
+            usage={"prompt_tokens": 5, "completion_tokens": 3},
+        )
+
+    provider.chat_stream_with_retry = chat_stream_with_retry
+    tools = MagicMock()
+    tools.get_definitions.return_value = []
+
+    class ReasoningHook(AgentHook):
+        async def emit_reasoning(self, reasoning_content: str | None) -> None:
+            if reasoning_content:
+                emitted_reasoning.append(reasoning_content)
+
+    async def _progress(content: str, **_kwargs):
+        pass
+
+    runner = AgentRunner(provider)
+    result = await runner.run(AgentRunSpec(
+        initial_messages=[{"role": "user", "content": "question"}],
+        tools=tools,
+        model="test-model",
+        max_iterations=3,
+        max_tool_result_chars=_MAX_TOOL_RESULT_CHARS,
+        hook=ReasoningHook(),
+        stream_progress_deltas=True,
+        progress_callback=_progress,
+    ))
+
+    assert result.final_content == "The answer."
+    assert emitted_reasoning == ["working..."]
+
+
 @pytest.mark.asyncio
 async def test_runner_calls_hooks_in_order():
     from nanobot.agent.hook import AgentHook, AgentHookContext

tests/cli/test_interactive_retry_wait.py

@@ -88,3 +88,26 @@ async def test_non_reasoning_progress_not_affected_by_show_reasoning():
 
     assert handled is True
     assert calls == ["working on it..."]
+
+
+@pytest.mark.asyncio
+async def test_reasoning_shown_when_send_progress_disabled():
+    """Reasoning display is governed by `show_reasoning` alone, independent
+    of `send_progress` — the two knobs are orthogonal."""
+    calls: list[str] = []
+    channels_config = SimpleNamespace(
+        send_progress=False, send_tool_hints=False, show_reasoning=True,
+    )
+    msg = SimpleNamespace(
+        content="Let me think about this...",
+        metadata={"_progress": True, "_reasoning": True},
+    )
+
+    with patch(
+        "nanobot.cli.commands._print_cli_reasoning",
+        side_effect=lambda t, th, r=None: calls.append(t),
+    ):
+        handled = await commands._maybe_print_interactive_progress(msg, None, channels_config)
+
+    assert handled is True
+    assert calls == ["Let me think about this..."]

tests/utils/test_strip_think.py

@@ -1,4 +1,4 @@
-from nanobot.utils.helpers import extract_think, strip_think
+from nanobot.utils.helpers import extract_reasoning, extract_think, strip_think
 
 
 class TestStripThinkTag:
@@ -225,3 +225,49 @@ squares = [x**2 for x in range(10)]
         assert "List comprehensions in Python" in clean
         assert "<think>" not in clean
         assert "</think>" not in clean
+
+
+class TestExtractReasoning:
+    """Single source of truth for reasoning extraction across all providers."""
+
+    def test_prefers_reasoning_content_and_strips_inline_think(self):
+        # Dedicated field wins; inline tags are still scrubbed from content.
+        reasoning, content = extract_reasoning(
+            "dedicated",
+            None,
+            "<think>inline</think>visible answer",
+        )
+        assert reasoning == "dedicated"
+        assert content == "visible answer"
+
+    def test_falls_back_to_thinking_blocks(self):
+        reasoning, content = extract_reasoning(
+            None,
+            [
+                {"type": "thinking", "thinking": "step 1"},
+                {"type": "thinking", "thinking": "step 2"},
+                {"type": "redacted_thinking"},
+            ],
+            "hello",
+        )
+        assert reasoning == "step 1\n\nstep 2"
+        assert content == "hello"
+
+    def test_falls_back_to_inline_think_tags(self):
+        reasoning, content = extract_reasoning(
+            None, None, "<think>plan</think>answer"
+        )
+        assert reasoning == "plan"
+        assert content == "answer"
+
+    def test_no_reasoning_returns_none(self):
+        reasoning, content = extract_reasoning(None, None, "plain answer")
+        assert reasoning is None
+        assert content == "plain answer"
+
+    def test_empty_thinking_blocks_falls_through_to_inline(self):
+        reasoning, content = extract_reasoning(
+            None, [], "<think>plan</think>answer"
+        )
+        assert reasoning == "plan"
+        assert content == "answer"