Implementation:Langchain ai Langchain Pyproject Version Edit

Overview

Concrete tool for setting the release version of a LangChain package, provided by manual editing of the [project].version field in pyproject.toml.

Description

Each package in the LangChain monorepo declares its version in its own pyproject.toml under the [project] table. Before triggering a release, a maintainer edits this field to the desired version string. The build system (Hatchling) and CI pipeline (_release.yml) both read this value at build time to stamp artifacts and create Git tags.

The version field follows PEP 440 semantics and supports:

• Stable versions: "1.2.11"
• Release candidates: "0.3.0rc1"
• Development builds: "0.3.0dev0"

The CI build job extracts the version using a Python step that loads the TOML file with tomllib and reads data["project"]["version"].

Usage

Edit the version field in the target package's pyproject.toml before initiating a release workflow. The value must be a valid PEP 440 version string.

Code Reference

Source Location: Each package directory under libs/, e.g.:

• libs/core/pyproject.toml
• libs/partners/openai/pyproject.toml
• libs/langchain_v1/pyproject.toml

Version Field Format:

[project]
name = "langchain-core"
version = "1.2.11"

Pre-release Convention:

[project]
name = "langchain-core"
version = "0.3.0rc1"

CI Extraction (from _release.yml build job, L85-98):

import os
import tomllib
with open("pyproject.toml", "rb") as f:
    data = tomllib.load(f)
pkg_name = data["project"]["name"]
version = data["project"]["version"]
with open(os.environ["GITHUB_OUTPUT"], "a") as f:
    f.write(f"pkg-name={pkg_name}\n")
    f.write(f"version={version}\n")

Invocation: Manual edit by a maintainer, then committed to the repository before triggering the release pipeline.

I/O Contract

Direction	Name	Type	Description
Input	pyproject.toml	File	The package metadata file containing the [project].version field
Input	new version string	String	A PEP 440-compliant version (e.g., "1.2.11", "0.3.0rc1")
Output	updated pyproject.toml	File	The file with the version field set to the new value
Output (CI)	pkg-name	String	Package name extracted from [project].name
Output (CI)	version	String	Version string extracted from [project].version

Usage Examples

Example 1: Stable release bump

# Before
[project]
name = "langchain-openai"
version = "1.1.8"

# After
[project]
name = "langchain-openai"
version = "1.1.9"

Example 2: Release candidate

# Before
[project]
name = "langchain-core"
version = "1.2.11"

# After (preparing an RC for next minor)
[project]
name = "langchain-core"
version = "1.3.0rc1"

Example 3: Verifying the version locally

import tomllib
with open("libs/core/pyproject.toml", "rb") as f:
    data = tomllib.load(f)
print(data["project"]["version"])  # "1.2.11"

Related Pages

• Principle:Langchain_ai_Langchain_Version_Bumping