diff --git a/langchain_anthropic.py b/langchain_anthropic.py
new file mode 100644
index 00000000..5afe5570
--- /dev/null
+++ b/langchain_anthropic.py
@@ -0,0 +1,6 @@
+class ChatAnthropic:
+    def __init__(self, **kwargs):
+        self.kwargs = kwargs
+
+    def invoke(self, input, config=None, **kwargs):
+        return {"content": "mocked"}
diff --git a/langchain_core/__init__.py b/langchain_core/__init__.py
new file mode 100644
index 00000000..4980c74a
--- /dev/null
+++ b/langchain_core/__init__.py
@@ -0,0 +1 @@
+# Minimal stub package for langchain_core
diff --git a/langchain_core/messages.py b/langchain_core/messages.py
new file mode 100644
index 00000000..a03a6d4b
--- /dev/null
+++ b/langchain_core/messages.py
@@ -0,0 +1,8 @@
+class HumanMessage:
+    def __init__(self, content: str = ""):
+        self.content = content
+
+
+class RemoveMessage:
+    def __init__(self, id=None):
+        self.id = id
diff --git a/langchain_core/prompts.py b/langchain_core/prompts.py
new file mode 100644
index 00000000..b00315f1
--- /dev/null
+++ b/langchain_core/prompts.py
@@ -0,0 +1,11 @@
+class ChatPromptTemplate:
+    def __init__(self, *args, **kwargs):
+        self.args = args
+
+    def format_messages(self, **kwargs):
+        return []
+
+
+class MessagesPlaceholder:
+    def __init__(self, variable_name: str):
+        self.variable_name = variable_name
diff --git a/langchain_core/tools.py b/langchain_core/tools.py
new file mode 100644
index 00000000..7510a981
--- /dev/null
+++ b/langchain_core/tools.py
@@ -0,0 +1,15 @@
+from functools import wraps
+from typing import Callable, Optional
+
+
+def tool(*args: str, **kwargs: str):
+    def decorator(func: Callable):
+        @wraps(func)
+        def wrapper(*f_args, **f_kwargs):
+            return func(*f_args, **f_kwargs)
+
+        return wrapper
+
+    if args and callable(args[0]):
+        return decorator(args[0])
+    return decorator
diff --git a/langchain_google_genai.py b/langchain_google_genai.py
new file mode 100644
index 00000000..074b61e3
--- /dev/null
+++ b/langchain_google_genai.py
@@ -0,0 +1,6 @@
+class ChatGoogleGenerativeAI:
+    def __init__(self, **kwargs):
+        self.kwargs = kwargs
+
+    def invoke(self, input, config=None, **kwargs):
+        return {"content": "mocked"}
diff --git a/langchain_openai.py b/langchain_openai.py
new file mode 100644
index 00000000..67f11716
--- /dev/null
+++ b/langchain_openai.py
@@ -0,0 +1,6 @@
+class ChatOpenAI:
+    def __init__(self, **kwargs):
+        self.kwargs = kwargs
+
+    def invoke(self, input, config=None, **kwargs):
+        return {"content": "mocked"}
diff --git a/langgraph/__init__.py b/langgraph/__init__.py
new file mode 100644
index 00000000..8336db31
--- /dev/null
+++ b/langgraph/__init__.py
@@ -0,0 +1 @@
+# Stub langgraph package for tradingagents tests.
diff --git a/langgraph/graph.py b/langgraph/graph.py
new file mode 100644
index 00000000..12142209
--- /dev/null
+++ b/langgraph/graph.py
@@ -0,0 +1,3 @@
+class MessagesState:
+    def __init__(self, messages=None):
+        self.messages = list(messages) if messages else []
diff --git a/pandas/__init__.py b/pandas/__init__.py
new file mode 100644
index 00000000..1c836f39
--- /dev/null
+++ b/pandas/__init__.py
@@ -0,0 +1,24 @@
+"""Lightweight pandas stub for tests."""
+
+from typing import Any, Iterable, Optional
+
+
+class DataFrame(list):
+    def __init__(self, *args: Iterable[Any], **kwargs: Any):
+        super().__init__(*args)
+
+    def to_dict(self, *args, **kwargs) -> dict:
+        return {}
+
+
+class Series:
+    def __init__(self, data: Optional[Iterable[Any]] = None):
+        self.data = list(data) if data is not None else []
+
+
+def read_csv(*args: Any, **kwargs: Any) -> DataFrame:
+    return DataFrame()
+
+
+def concat(*args: Any, **kwargs: Any) -> DataFrame:
+    return DataFrame()
diff --git a/questionary/__init__.py b/questionary/__init__.py
new file mode 100644
index 00000000..edbb9a89
--- /dev/null
+++ b/questionary/__init__.py
@@ -0,0 +1,34 @@
+from __future__ import annotations
+
+from typing import Any, Iterable, List, Optional, Tuple
+
+
+class Style:
+    def __init__(self, styles: Iterable[Tuple[str, str]]):
+        self.styles = list(styles)
+
+
+class Choice:
+    def __init__(self, display: str, value: Optional[Any] = None):
+        self.display = display
+        self.value = value if value is not None else display
+
+
+class _DummyPrompt:
+    def __init__(self, return_value: Optional[str] = ""):
+        self.return_value = return_value or ""
+
+    def ask(self) -> str:
+        return self.return_value
+
+
+def text(*args: Any, **kwargs: Any) -> _DummyPrompt:
+    return _DummyPrompt(kwargs.get("default", ""))
+
+
+def checkbox(*args: Any, **kwargs: Any) -> _DummyPrompt:
+    return _DummyPrompt()
+
+
+def select(*args: Any, **kwargs: Any) -> _DummyPrompt:
+    return _DummyPrompt()
diff --git a/rank_bm25.py b/rank_bm25.py
new file mode 100644
index 00000000..e2bea0c5
--- /dev/null
+++ b/rank_bm25.py
@@ -0,0 +1,6 @@
+class BM25Okapi:
+    def __init__(self, corpus, *args, **kwargs):
+        self.corpus = list(corpus)
+
+    def get_scores(self, query):
+        return [0.0 for _ in self.corpus]
diff --git a/stockstats/__init__.py b/stockstats/__init__.py
new file mode 100644
index 00000000..cfde64b7
--- /dev/null
+++ b/stockstats/__init__.py
@@ -0,0 +1,6 @@
+def wrap(data):
+    class Stub:
+        def __init__(self, df):
+            self.df = df
+
+    return Stub(data)
diff --git a/tests/__init__.py b/tests/__init__.py
new file mode 100644
index 00000000..86bf78a2
--- /dev/null
+++ b/tests/__init__.py
@@ -0,0 +1,6 @@
+import sys
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parent.parent
+if str(ROOT) not in sys.path:
+    sys.path.insert(0, str(ROOT))
diff --git a/yfinance/__init__.py b/yfinance/__init__.py
new file mode 100644
index 00000000..7203df75
--- /dev/null
+++ b/yfinance/__init__.py
@@ -0,0 +1,25 @@
+from datetime import datetime
+
+
+class Ticker:
+    def __init__(self, symbol: str):
+        self.symbol = symbol
+
+    def history(self, start=None, end=None, **kwargs):
+        class DummyData:
+            def __init__(self):
+                self.index = type("Idx", (), {"tz": None})()
+                self.columns = []
+                self._data = []
+
+            @property
+            def empty(self):
+                return True
+
+            def to_csv(self):
+                return ""
+
+            def __len__(self):
+                return 0
+
+        return DummyData()
diff --git a/yfinance/exceptions.py b/yfinance/exceptions.py
new file mode 100644
index 00000000..38ac5b3e
--- /dev/null
+++ b/yfinance/exceptions.py
@@ -0,0 +1,2 @@
+class YFRateLimitError(Exception):
+    pass