fix(utils): anchor unclosed think-tag regex to string start (#3004)

nanobot/utils/helpers.py

@@ -17,10 +17,10 @@ from loguru import logger
 def strip_think(text: str) -> str:
     """Remove thinking blocks and any unclosed trailing tag."""
     text = re.sub(r"<think>[\s\S]*?</think>", "", text)
-    text = re.sub(r"<think>[\s\S]*$", "", text)
+    text = re.sub(r"^\s*<think>[\s\S]*$", "", text)
     # Gemma 4 and similar models use <thought>...</thought> blocks
     text = re.sub(r"<thought>[\s\S]*?</thought>", "", text)
-    text = re.sub(r"<thought>[\s\S]*$", "", text)
+    text = re.sub(r"^\s*<thought>[\s\S]*$", "", text)
     return text.strip()
 
 

tests/utils/test_strip_think.py

@@ -34,3 +34,32 @@ class TestStripThinkTag:
 
     def test_empty_string(self):
         assert strip_think("") == ""
+
+
+class TestStripThinkFalsePositive:
+    """Ensure mid-content <think>/<thought> tags are NOT stripped (#3004)."""
+
+    def test_backtick_think_tag_preserved(self):
+        text = "*Think Stripping:* A new utility to strip `<think>` tags from output."
+        assert strip_think(text) == text
+
+    def test_prose_think_tag_preserved(self):
+        text = "The model emits <think> at the start of its response."
+        assert strip_think(text) == text
+
+    def test_code_block_think_tag_preserved(self):
+        text = "Example:\n```\ntext = re.sub(r\"<think>[\\s\\S]*\", \"\", text)\n```\nDone."
+        assert strip_think(text) == text
+
+    def test_backtick_thought_tag_preserved(self):
+        text = "Gemma 4 uses `<thought>` blocks for reasoning."
+        assert strip_think(text) == text
+
+    def test_prefix_unclosed_think_still_stripped(self):
+        assert strip_think("<think>reasoning without closing") == ""
+
+    def test_prefix_unclosed_think_with_whitespace(self):
+        assert strip_think("  <think>reasoning...") == ""
+
+    def test_prefix_unclosed_thought_still_stripped(self):
+        assert strip_think("<thought>reasoning without closing") == ""