From 4445fcc8b99dd7199c21c373f1c895318c701cf1 Mon Sep 17 00:00:00 2001
From: Xubin Ren <52506698+Re-bin@users.noreply.github.com>
Date: Sun, 17 May 2026 23:58:03 +0800
Subject: [PATCH] refactor(cli): localize reasoning buffer state

---
 nanobot/cli/commands.py                  | 104 ++++++++++++++---------
 tests/cli/test_interactive_retry_wait.py |  66 ++++++++++++++
 2 files changed, 132 insertions(+), 38 deletions(-)

diff --git a/nanobot/cli/commands.py b/nanobot/cli/commands.py
index 800c6f19f..e561906fb 100644
--- a/nanobot/cli/commands.py
+++ b/nanobot/cli/commands.py
@@ -22,11 +22,6 @@ if sys.platform == "win32":
 import typer
 from loguru import logger
 
-# Buffered reasoning display: accumulate streaming tokens and flush
-# on sentence/line boundaries so the user sees grouped text instead of
-# one token per line. The empty string placeholder is the sentinel.
-_reasoning_buf: str = ""
-
 # Remove default handler and re-add with unified nanobot format
 logger.remove()
 _log_handler_id = logger.add(
@@ -96,6 +91,8 @@ app = typer.Typer(
 
 console = Console()
 EXIT_COMMANDS = {"exit", "quit", "/exit", "/quit", ":q"}
+_REASONING_SENTENCE_ENDINGS = (".", "!", "?", "。", "！", "？")
+_REASONING_FLUSH_CHARS = 60
 
 # ---------------------------------------------------------------------------
 # CLI input: prompt_toolkit for editing, paste, history, and display
@@ -247,14 +244,39 @@ def _print_cli_progress_line(text: str, thinking: ThinkingSpinner | None, render
         target.print(f"  [dim]↳ {text}[/dim]")
 
 
-def _flush_reasoning(thinking: ThinkingSpinner | None, renderer: StreamRenderer | None = None) -> None:
-    """Flush accumulated reasoning buffer to the display."""
-    global _reasoning_buf
-    if not _reasoning_buf or not _reasoning_buf.strip():
-        _reasoning_buf = ""
+class _ReasoningBuffer:
+    def __init__(self) -> None:
+        self._text = ""
+
+    def add(self, text: str) -> str | None:
+        if not text:
+            return None
+        self._text += text
+        if self._should_flush(text):
+            return self.flush()
+        return None
+
+    def flush(self) -> str | None:
+        text = self._text.strip()
+        self._text = ""
+        return text or None
+
+    def clear(self) -> None:
+        self._text = ""
+
+    def _should_flush(self, text: str) -> bool:
+        stripped = text.rstrip()
+        return (
+            "\n" in text
+            or stripped.endswith(_REASONING_SENTENCE_ENDINGS)
+            or len(self._text) >= _REASONING_FLUSH_CHARS
+        )
+
+
+def _print_cli_reasoning(text: str, thinking: ThinkingSpinner | None, renderer: StreamRenderer | None = None) -> None:
+    """Print reasoning/thinking content in a distinct style."""
+    if not text.strip():
         return
-    text = _reasoning_buf.strip()
-    _reasoning_buf = ""
     target = renderer.console if renderer else console
     pause = renderer.pause_spinner() if renderer else (thinking.pause() if thinking else nullcontext())
     with pause:
@@ -263,26 +285,14 @@ def _flush_reasoning(thinking: ThinkingSpinner | None, renderer: StreamRenderer
         target.print(f"[dim italic]✻ {text}[/dim italic]")
 
 
-def _print_cli_reasoning(text: str, thinking: ThinkingSpinner | None, renderer: StreamRenderer | None = None) -> None:
-    """Accumulate reasoning tokens and flush on sentence / line boundaries.
-
-    Without buffering, each streaming delta (often a single token) would be
-    printed as a separate ``✻`` line.  This version groups tokens into
-    natural chunks visible in the terminal.
-    """
-    global _reasoning_buf
-    if not text:
-        return
-    _reasoning_buf += text
-
-    # Flush on newline, sentence-ending punctuation, or when the chunk is
-    # long enough to wrap meaningfully at typical terminal widths.
-    if (
-        text.endswith("\n")
-        or any(text.rstrip().endswith(p) for p in (".", "!", "?", "。", "！", "？"))
-        or len(_reasoning_buf) >= 60
-    ):
-        _flush_reasoning(thinking, renderer)
+def _flush_cli_reasoning(
+    reasoning_buffer: _ReasoningBuffer,
+    thinking: ThinkingSpinner | None,
+    renderer: StreamRenderer | None = None,
+) -> None:
+    text = reasoning_buffer.flush()
+    if text:
+        _print_cli_reasoning(text, thinking, renderer)
 
 
 async def _print_interactive_progress_line(text: str, thinking: ThinkingSpinner | None, renderer: StreamRenderer | None = None) -> None:
@@ -303,6 +313,7 @@ async def _maybe_print_interactive_progress(
     thinking: ThinkingSpinner | None,
     channels_config: Any,
     renderer: StreamRenderer | None = None,
+    reasoning_buffer: _ReasoningBuffer | None = None,
 ) -> bool:
     metadata = msg.metadata or {}
     if metadata.get("_retry_wait"):
@@ -312,17 +323,24 @@ async def _maybe_print_interactive_progress(
     if not metadata.get("_progress"):
         return False
 
-    # Flush reasoning buffer when the reasoning stream ends (bus path).
+    reasoning_buffer = reasoning_buffer or _ReasoningBuffer()
+
     if metadata.get("_reasoning_end"):
-        _flush_reasoning(thinking, renderer)
+        if channels_config and not channels_config.show_reasoning:
+            reasoning_buffer.clear()
+        else:
+            _flush_cli_reasoning(reasoning_buffer, thinking, renderer)
         return True
 
     is_tool_hint = metadata.get("_tool_hint", False)
     is_reasoning = metadata.get("_reasoning", False) or metadata.get("_reasoning_delta", False)
     if is_reasoning:
         if channels_config and not channels_config.show_reasoning:
+            reasoning_buffer.clear()
             return True
-        _print_cli_reasoning(msg.content, thinking, renderer)
+        text = reasoning_buffer.add(msg.content)
+        if text:
+            _print_cli_reasoning(text, thinking, renderer)
         return True
     if channels_config and is_tool_hint and not channels_config.send_tool_hints:
         return True
@@ -1143,18 +1161,25 @@ def agent(
     _thinking: ThinkingSpinner | None = None
 
     def _make_progress(renderer: StreamRenderer | None = None):
+        reasoning_buffer = _ReasoningBuffer()
+
         async def _cli_progress(content: str, *, tool_hint: bool = False, reasoning: bool = False, **_kwargs: Any) -> None:
             ch = agent_loop.channels_config
 
-            # Flush remaining reasoning buffer when the stream ends.
             if _kwargs.get("reasoning_end"):
-                _flush_reasoning(_thinking, renderer)
+                if ch and not ch.show_reasoning:
+                    reasoning_buffer.clear()
+                else:
+                    _flush_cli_reasoning(reasoning_buffer, _thinking, renderer)
                 return
 
             if reasoning:
                 if ch and not ch.show_reasoning:
+                    reasoning_buffer.clear()
                     return
-                _print_cli_reasoning(content, _thinking, renderer)
+                text = reasoning_buffer.add(content)
+                if text:
+                    _print_cli_reasoning(text, _thinking, renderer)
                 return
             if ch and tool_hint and not ch.send_tool_hints:
                 return
@@ -1225,6 +1250,7 @@ def agent(
             turn_done.set()
             turn_response: list[tuple[str, dict]] = []
             renderer: StreamRenderer | None = None
+            reasoning_buffer = _ReasoningBuffer()
 
             async def _consume_outbound():
                 while True:
@@ -1250,6 +1276,7 @@ def agent(
                             renderer,
                             agent_loop.channels_config,
                             renderer,
+                            reasoning_buffer,
                         ):
                             continue
 
@@ -1290,6 +1317,7 @@ def agent(
 
                         turn_done.clear()
                         turn_response.clear()
+                        reasoning_buffer.clear()
                         renderer = StreamRenderer(
                             render_markdown=markdown,
                             bot_name=config.agents.defaults.bot_name,
diff --git a/tests/cli/test_interactive_retry_wait.py b/tests/cli/test_interactive_retry_wait.py
index 52c27d2c9..5eeb2c128 100644
--- a/tests/cli/test_interactive_retry_wait.py
+++ b/tests/cli/test_interactive_retry_wait.py
@@ -69,6 +69,72 @@ async def test_reasoning_delta_displayed_when_show_reasoning_enabled():
     assert calls == ["I should search first."]
 
 
+@pytest.mark.asyncio
+async def test_reasoning_delta_buffers_until_sentence_boundary():
+    calls: list[str] = []
+    channels_config = SimpleNamespace(
+        send_progress=True, send_tool_hints=False, show_reasoning=True,
+    )
+    reasoning_buffer = commands._ReasoningBuffer()
+
+    with patch("nanobot.cli.commands._print_cli_reasoning", side_effect=lambda t, th, r=None: calls.append(t)):
+        first = await commands._maybe_print_interactive_progress(
+            SimpleNamespace(
+                content="The",
+                metadata={"_progress": True, "_reasoning_delta": True},
+            ),
+            None,
+            channels_config,
+            reasoning_buffer=reasoning_buffer,
+        )
+        second = await commands._maybe_print_interactive_progress(
+            SimpleNamespace(
+                content=" user asked.",
+                metadata={"_progress": True, "_reasoning_delta": True},
+            ),
+            None,
+            channels_config,
+            reasoning_buffer=reasoning_buffer,
+        )
+
+    assert first is True
+    assert second is True
+    assert calls == ["The user asked."]
+
+
+@pytest.mark.asyncio
+async def test_reasoning_end_flushes_buffered_delta():
+    calls: list[str] = []
+    channels_config = SimpleNamespace(
+        send_progress=True, send_tool_hints=False, show_reasoning=True,
+    )
+    reasoning_buffer = commands._ReasoningBuffer()
+
+    with patch("nanobot.cli.commands._print_cli_reasoning", side_effect=lambda t, th, r=None: calls.append(t)):
+        delta = await commands._maybe_print_interactive_progress(
+            SimpleNamespace(
+                content="The user asked",
+                metadata={"_progress": True, "_reasoning_delta": True},
+            ),
+            None,
+            channels_config,
+            reasoning_buffer=reasoning_buffer,
+        )
+        end = await commands._maybe_print_interactive_progress(
+            SimpleNamespace(
+                content="",
+                metadata={"_progress": True, "_reasoning_end": True},
+            ),
+            None,
+            channels_config,
+            reasoning_buffer=reasoning_buffer,
+        )
+
+    assert delta is True
+    assert end is True
+    assert calls == ["The user asked"]
+
+
 @pytest.mark.asyncio
 async def test_reasoning_hidden_when_show_reasoning_disabled():
     """Reasoning content should be suppressed when show_reasoning is False."""