From ac25864e92971bb9e17430734b1c94d3812cfefe Mon Sep 17 00:00:00 2001
From: BREW <81044362+b-re-w@users.noreply.github.com>
Date: Sat, 3 Oct 2026 15:09:19 +0900
Subject: [PATCH] Fix: Send reasoning and tool tags as frames of their own

The app opens the reasoning panel only on a frame that is exactly
<think> or </think>. On the one-at-a-time path TextIteratorStreamer
emits at word boundaries, and with Qwen3's tokenizer the tags arrive as
'<think>\n' and '</think>\n\n', so the panel never opened and the tags
showed up in the answer. The model layer now splits every special tag
into its own frame.
---
 api/src/main/models/base.py    | 18 +++++++++++++-
 api/tests/test_think_frames.py | 44 ++++++++++++++++++++++++++++++++++
 docs/SPEC.md                   |  3 ++-
 3 files changed, 63 insertions(+), 2 deletions(-)
 create mode 100644 api/tests/test_think_frames.py

diff --git a/api/src/main/models/base.py b/api/src/main/models/base.py
index 9307d620..e428e3c9 100644
--- a/api/src/main/models/base.py
+++ b/api/src/main/models/base.py
@@ -1,4 +1,5 @@
 import logging
+import re
 from re import finditer, DOTALL
 from dataclasses import dataclass
 from typing import Generator, Optional, List, Dict, Union
@@ -172,6 +173,21 @@ def adaptive_special_tag_buffering(outs, wait_tokens_for=6):
                 else:
                     yield wd
 
+        tag_pattern = re.compile("(" + "|".join(re.escape(t) for t in (
+            self.special_tags.REASONING, self.special_tags.REASONING_END,
+            self.special_tags.TOOLCALL, self.special_tags.TOOLCALL_END,
+        )) + ")")
+
+        def split_special_tags(outs):
+            """
+            Give every special tag a frame of its own. The app matches `<think>`/`</think>` exactly, and a
+            streamer that emits at word boundaries glues tags to whitespace or text (`'<think>\\n'`).
+            """
+            for wd in outs:
+                for piece in tag_pattern.split(wd):
+                    if piece:
+                        yield piece
+
         initial_operation = True
         function_called = True
         while function_called:
@@ -206,7 +222,7 @@ def adaptive_special_tag_buffering(outs, wait_tokens_for=6):
             )
             generation_kwargs.update(kwargs)
             outputs = self.parse_tool_calling(
-                adaptive_special_tag_buffering(self.runtime(**generation_kwargs)),
+                split_special_tags(adaptive_special_tag_buffering(self.runtime(**generation_kwargs))),
                 chat_history=chat_history,
                 tools=tools,
                 stream=stream,
diff --git a/api/tests/test_think_frames.py b/api/tests/test_think_frames.py
new file mode 100644
index 00000000..71952ec5
--- /dev/null
+++ b/api/tests/test_think_frames.py
@@ -0,0 +1,44 @@
+"""
+Reasoning and tool tags reach the app as frames of their own (SPEC S1.4, #112): the app matches
+`<think>` and `</think>` exactly, and the one-at-a-time path's streamer glues them to whitespace
+(`'<think>\n'`, `'</think>\n\n'`).
+"""
+from api.src.main.models.base import BaseModel
+from api.src.main.models.config import ChatHistory
+from api.src.main.utils import FunctionCalling
+
+
+class ScriptedEngine:
+    def __init__(self, chunks):
+        self.chunks = chunks
+
+    def __call__(self, messages, **kwargs):
+        yield from self.chunks
+
+
+class Plain(BaseModel):
+    model_id = "test"
+    supported_tools = FunctionCalling.DISABLED
+
+
+def frames(chunks):
+    model = Plain(engine=ScriptedEngine(chunks))
+    return [f for f in model.chat(ChatHistory(), "Hi", tools=[]) if f]
+
+
+def test_think_tags_glued_to_whitespace_become_their_own_frames():
+    out = frames(["<think>\n", "The user ", "greets me.", "\n</think>\n\n", "Hello", "!"])
+
+    assert "<think>" in out
+    assert "</think>" in out
+    assert "".join(out) == "<think>\nThe user greets me.\n</think>\n\nHello!"
+
+
+def test_text_and_tag_in_one_chunk_are_split():
+    out = frames(["ok<think>", "x", "</think>done"])
+
+    assert out == ["ok", "<think>", "x", "</think>", "done"]
+
+
+def test_text_without_tags_is_untouched():
+    assert frames(["Hello", " world"]) == ["Hello", " world"]
diff --git a/docs/SPEC.md b/docs/SPEC.md
index 95c82198..e4a24448 100644
--- a/docs/SPEC.md
+++ b/docs/SPEC.md
@@ -91,7 +91,8 @@ and S3.4 also record the maintainer's decisions of the same day ([`serving/engin
 
 The server then sends one text frame per generated chunk, then `<EOS>`, then closes. An unknown
 session closes the socket with code `1008`. Reasoning arrives between `<think>` and `</think>`
-frames; tool activity arrives as `<tool_call> … </tool_call>` frames (S1.6). Generation runs off
+frames; tool activity arrives as `<tool_call> … </tool_call>` frames (S1.6). Each tag is a frame of its own,
+even when the model's streamer emits it glued to whitespace or text (#112). Generation runs off
 the event loop; if the client disconnects mid-stream, generation stops and the model is free for
 the next request (#35).