Merge branch 'master' into wip-v1.0

Author: mdrxy

README.md

@@ -83,3 +83,4 @@ concepts behind the LangChain framework.
 - [LangChain Forum](https://forum.langchain.com/): Connect with the community and share all of your technical questions, ideas, and feedback.
 - [API Reference](https://python.langchain.com/api_reference/): Detailed reference on
 navigating base packages and integrations for LangChain.
+- [Chat LangChain](https://chat.langchain.com/): Ask questions & chat with our documentation

docs/docs/contributing/how_to/code/setup.mdx

@@ -223,6 +223,49 @@ If codespell is incorrectly flagging a word, you can skip spellcheck for that wo
 ignore-words-list = 'momento,collison,ned,foor,reworkd,parth,whats,aapply,mysogyny,unsecure'
 ```
 
+### Pre-commit
+
+We use [pre-commit](https://pre-commit.com/) to ensure commits are formatted/linted.
+
+#### Installing Pre-commit
+
+First, install pre-commit:
+
+```bash
+# Option 1: Using uv (recommended)
+uv tool install pre-commit
+
+# Option 2: Using Homebrew (globally for macOS/Linux)
+brew install pre-commit
+
+# Option 3: Using pip
+pip install pre-commit
+```
+
+Then install the git hook scripts:
+
+```bash
+pre-commit install
+```
+
+#### How Pre-commit Works
+
+Once installed, pre-commit will automatically run on every `git commit`. Hooks are specified in `.pre-commit-config.yaml` and will:
+
+- Format code using `ruff` for the specific library/package you're modifying
+- Only run on files that have changed
+- Prevent commits if formatting fails
+
+#### Skipping Pre-commit
+
+In exceptional cases, you can skip pre-commit hooks with:
+
+```bash
+git commit --no-verify
+```
+
+However, this is discouraged as the CI system will still enforce the same formatting rules.
+
 ## Working with optional dependencies
 
 `langchain`, `langchain-community`, and `langchain-experimental` rely on optional dependencies to keep these packages lightweight.

docs/docs/how_to/trim_messages.ipynb

@@ -53,7 +53,7 @@
     "\n",
     "To keep the most recent messages, we set `strategy=\"last\"`.  We'll also set `include_system=True` to include the `SystemMessage`, and `start_on=\"human\"` to make sure the resulting chat history is valid. \n",
     "\n",
-    "This is a good default configuration when using `trim_messages` based on token count. Remember to adjust `token_counter` and `max_tokens` for your use case.\n",
+    "This is a good default configuration when using `trim_messages` based on token count. Remember to adjust `token_counter` and `max_tokens` for your use case. Keep in mind that new queries added to the chat history will be included in the token count unless you trim prior to adding the new query.\n",
     "\n",
     "Notice that for our `token_counter` we can pass in a function (more on that below) or a language model (since language models have a message token counting method). It makes sense to pass in a model when you're trimming your messages to fit into the context window of that specific model:"
    ]
@@ -525,7 +525,7 @@
    "id": "4d91d390-e7f7-467b-ad87-d100411d7a21",
    "metadata": {},
    "source": [
-    "Looking at the LangSmith trace we can see that before the messages are passed to the model they are first trimmed: https://smith.langchain.com/public/65af12c4-c24d-4824-90f0-6547566e59bb/r\n",
+    "Looking at [the LangSmith trace](https://smith.langchain.com/public/65af12c4-c24d-4824-90f0-6547566e59bb/r) we can see that before the messages are passed to the model they are first trimmed.\n",
     "\n",
     "Looking at just the trimmer, we can see that it's a Runnable object that can be invoked like all Runnables:"
    ]
@@ -620,7 +620,7 @@
    "id": "556b7b4c-43cb-41de-94fc-1a41f4ec4d2e",
    "metadata": {},
    "source": [
-    "Looking at the LangSmith trace we can see that we retrieve all of our messages but before the messages are passed to the model they are trimmed to be just the system message and last human message: https://smith.langchain.com/public/17dd700b-9994-44ca-930c-116e00997315/r"
+    "Looking at [the LangSmith trace](https://smith.langchain.com/public/17dd700b-9994-44ca-930c-116e00997315/r) we can see that we retrieve all of our messages but before the messages are passed to the model they are trimmed to be just the system message and last human message."
    ]
   },
   {
@@ -630,7 +630,7 @@
    "source": [
     "## API reference\n",
     "\n",
-    "For a complete description of all arguments head to the API reference: https://python.langchain.com/api_reference/core/messages/langchain_core.messages.utils.trim_messages.html"
+    "For a complete description of all arguments head to the [API reference](https://python.langchain.com/api_reference/core/messages/langchain_core.messages.utils.trim_messages.html)."
    ]
   }
  ],