diff --git a/ai_agents/agents/ten_packages/extension/openai_llm2_python/tests/conftest.py b/ai_agents/agents/ten_packages/extension/openai_llm2_python/tests/conftest.py
new file mode 100644
index 0000000000..9d08e1f2a7
--- /dev/null
+++ b/ai_agents/agents/ten_packages/extension/openai_llm2_python/tests/conftest.py
@@ -0,0 +1,57 @@
+#
+# This file is part of TEN Framework, an open source project.
+# Licensed under the Apache License, Version 2.0.
+# See the LICENSE file for more information.
+#
+# conftest.py — stub out ten_runtime and ten_ai_base before the extension
+# package is imported, so that unit tests for pure-Python helpers can run
+# without a full TEN runtime installation.
+#
+import sys
+import types
+from unittest.mock import MagicMock
+
+
+def _make_mock_module(name: str) -> types.ModuleType:
+    mod = types.ModuleType(name)
+    mod.__spec__ = None  # type: ignore[assignment]
+    # Make attribute access return a MagicMock (useful for sub-attributes).
+    mod.__getattr__ = lambda attr: MagicMock()  # type: ignore[method-assign]
+    return mod
+
+
+# Stub top-level packages and the sub-modules the extension imports.
+_STUB_MODULES = [
+    "ten_runtime",
+    "ten_runtime.async_ten_env",
+    "ten_ai_base",
+    "ten_ai_base.llm2",
+    "ten_ai_base.llm",
+    "ten_ai_base.struct",
+    "ten_ai_base.types",
+    "ten_ai_base.config",
+    "ten_ai_base.const",
+    "ten_ai_base.helper",
+    "ten_ai_base.message",
+    "ten_ai_base.utils",
+    "ten_ai_base.tts2",
+]
+
+for _name in _STUB_MODULES:
+    if _name not in sys.modules:
+        sys.modules[_name] = _make_mock_module(_name)
+
+# Provide concrete stubs for names actually used at import time.
+_ten_runtime = sys.modules["ten_runtime"]
+for _attr in (
+    "Addon",
+    "AsyncExtension",
+    "AsyncTenEnv",
+    "Cmd",
+    "CmdResult",
+    "Data",
+    "StatusCode",
+    "TenEnv",
+    "register_addon_as_extension",
+):
+    setattr(_ten_runtime, _attr, MagicMock())
diff --git a/ai_agents/agents/ten_packages/extension/openai_llm2_python/tests/test_think_parser.py b/ai_agents/agents/ten_packages/extension/openai_llm2_python/tests/test_think_parser.py
new file mode 100644
index 0000000000..b432e3590d
--- /dev/null
+++ b/ai_agents/agents/ten_packages/extension/openai_llm2_python/tests/test_think_parser.py
@@ -0,0 +1,152 @@
+#
+# This file is part of TEN Framework, an open source project.
+# Licensed under the Apache License, Version 2.0.
+# See the LICENSE file for more information.
+#
+import importlib.util
+import sys
+from pathlib import Path
+
+# Load think_parser directly from its source file to avoid importing the
+# extension package __init__ (which requires ten_runtime).
+_think_parser_path = Path(__file__).resolve().parents[1] / "think_parser.py"
+_spec = importlib.util.spec_from_file_location("think_parser", _think_parser_path)
+_mod = importlib.util.module_from_spec(_spec)
+_spec.loader.exec_module(_mod)
+ThinkParser = _mod.ThinkParser
+
+
+# ============================================================
+# ThinkParser.process_content
+# ============================================================
+
+
+def test_plain_text_produces_message_delta():
+    parser = ThinkParser()
+    events = parser.process_content("Hello world")
+    assert events == [("message_delta", "Hello world")]
+
+
+def test_think_block_produces_reasoning_events():
+    parser = ThinkParser()
+    events = parser.process_content("<think>reason</think>answer")
+    types = [e[0] for e in events]
+    assert "reasoning_delta" in types
+    assert "reasoning_done" in types
+    assert "message_delta" in types
+
+
+def test_think_block_reasoning_content():
+    parser = ThinkParser()
+    events = parser.process_content("<think>step one</think>")
+    reasoning_deltas = [v for t, v in events if t == "reasoning_delta"]
+    assert reasoning_deltas == ["step one"]
+    reasoning_done = [v for t, v in events if t == "reasoning_done"]
+    assert reasoning_done == ["step one"]
+
+
+def test_message_after_think_block():
+    parser = ThinkParser()
+    events = parser.process_content("<think>r</think>answer")
+    message_deltas = [v for t, v in events if t == "message_delta"]
+    assert "answer" in message_deltas
+
+
+def test_empty_input_returns_no_events():
+    parser = ThinkParser()
+    assert parser.process_content("") == []
+
+
+def test_partial_open_tag_buffered():
+    """Content ending with partial <think> prefix should be held in pending."""
+    parser = ThinkParser()
+    events = parser.process_content("Hello <th")
+    # "Hello " is emitted; "<th" is pending (possible start of <think>)
+    assert events == [("message_delta", "Hello ")]
+    assert parser._pending == "<th"
+
+
+def test_partial_open_tag_resolved_on_next_chunk():
+    """A buffered partial open tag that turns out NOT to be <think> should flush."""
+    parser = ThinkParser()
+    parser.process_content("Hello <th")
+    events = parser.process_content("e end")
+    # "<the end" is not a think tag — should be emitted as message_delta
+    combined = "".join(v for t, v in events if t == "message_delta")
+    assert "<th" in combined or "e end" in combined
+
+
+def test_split_think_tag_across_chunks():
+    """<think> split across two chunks should still be detected."""
+    parser = ThinkParser()
+    parser.process_content("<thi")
+    events = parser.process_content("nk>reason</think>")
+    types = [e[0] for e in events]
+    assert "reasoning_delta" in types
+
+
+def test_state_returns_to_normal_after_think():
+    parser = ThinkParser()
+    parser.process_content("<think>r</think>")
+    assert parser.state == "NORMAL"
+
+
+def test_finalize_flushes_pending_normal():
+    parser = ThinkParser()
+    parser.process_content("hello <thi")
+    events = parser.finalize()
+    # pending "<thi" is flushed as message_delta (not a complete open tag)
+    assert any(t == "message_delta" for t, _ in events)
+
+
+def test_finalize_closes_open_think_block():
+    parser = ThinkParser()
+    parser.process_content("<think>unfinished")
+    events = parser.finalize()
+    types = [e[0] for e in events]
+    assert "reasoning_done" in types
+    assert parser.state == "NORMAL"
+
+
+def test_multiple_think_blocks():
+    parser = ThinkParser()
+    events = parser.process_content("<think>a</think>mid<think>b</think>end")
+    reasoning_done = [v for t, v in events if t == "reasoning_done"]
+    assert len(reasoning_done) == 2
+
+
+# ============================================================
+# ThinkParser.process_reasoning_content
+# ============================================================
+
+
+def test_process_reasoning_content_emits_delta():
+    parser = ThinkParser()
+    events = parser.process_reasoning_content("thinking...")
+    assert ("reasoning_delta", "thinking...") in events
+
+
+def test_process_reasoning_content_empty_closes_block():
+    parser = ThinkParser()
+    parser.process_reasoning_content("step one")
+    events = parser.process_reasoning_content("")
+    assert any(t == "reasoning_done" for t, _ in events)
+    assert parser.state == "NORMAL"
+
+
+# ============================================================
+# ThinkParser.process (legacy bool interface)
+# ============================================================
+
+
+def test_process_returns_false_for_plain_text():
+    parser = ThinkParser()
+    changed = parser.process("no tags here")
+    assert changed is False
+
+
+def test_process_returns_true_on_state_change():
+    parser = ThinkParser()
+    # Opening <think> transitions state NORMAL -> THINK
+    changed = parser.process("<think>reasoning</think>")
+    assert changed is True