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+++ b/AGENTS.md
@@ -1,3 +1,115 @@
+<general_rules>
+This repository is a monorepo where each library lives in a subdirectory under `libs/`. When modifying code in any library, you must run the following commands in that library's directory before creating a pull request:
+
+- `make format` – run code formatters (ruff)
+- `make lint` – run linters (ruff and mypy)
+- `make test` – execute the test suite
+
+To run a specific test file or pass additional pytest options, use the `TEST` variable:
+```bash
+TEST=path/to/test.py make test
+TEST="tests/test_specific.py -v" make test
+```
+
+All libraries use consistent code quality tools:
+- **ruff** for code formatting and linting (replaces black and flake8)
+- **mypy** for static type checking
+- All commands are prefixed with `uv run` in library Makefiles
+
+When creating new functionality, always search existing code in the relevant library first to avoid duplication. Follow the existing patterns for imports, error handling, and async/sync implementations found in each library.
+
+Root-level commands are available to operate across all libraries:
+- `make install` – install all library dependencies
+- `make format` – format code in all libraries
+- `make lint` – lint all libraries
+- `make test` – run tests in all libraries
+</general_rules>
+
+<repository_structure>
+This is a monorepo containing 8 main libraries in the `libs/` directory:
+
+**Core Libraries:**
+- **langgraph** – Core framework for building stateful, multi-actor agents
+- **checkpoint** – Base interfaces for LangGraph checkpointers
+- **prebuilt** – High-level APIs for creating and running agents and tools
+
+**Checkpoint Implementations:**
+- **checkpoint-postgres** – PostgreSQL implementation of checkpoint saver
+- **checkpoint-sqlite** – SQLite implementation of checkpoint saver
+
+**Platform Integration:**
+- **cli** – Official command-line interface for LangGraph
+- **sdk-py** – Python SDK for LangGraph Platform API
+- **sdk-js** – JavaScript/TypeScript SDK for LangGraph REST API
+
+**Dependency Relationships:**
+```
+checkpoint → checkpoint-postgres, checkpoint-sqlite, prebuilt, langgraph
+prebuilt → langgraph
+sdk-py → langgraph, cli
+sdk-js (standalone)
+```
+
+Each library contains:
+- `pyproject.toml` – dependency and tool configuration
+- `Makefile` – standardized build targets
+- `tests/` – test files with fixtures and conftest.py
+- `uv.lock` – locked dependency versions
+
+The `docs/` directory contains documentation built with MkDocs, and `examples/` contains Jupyter notebooks demonstrating LangGraph features.
+</repository_structure>
+
+<dependencies_and_installation>
+This repository uses **uv** as the primary package manager (not pip or poetry). Dependencies are managed through `pyproject.toml` files with `uv.lock` files for version locking.
+
+**Installation:**
+```bash
+make install  # Installs all libraries with dependencies
+```
+
+This command creates a virtual environment and installs all libraries in `libs/` as editable packages using `uv pip install -e`.
+
+**Library Interdependencies:**
+Libraries reference each other through `uv.sources` sections in their `pyproject.toml` files using path-based editable installs. For example:
+```toml
+[tool.uv.sources]
+langgraph-checkpoint = { path = "../checkpoint", editable = true }
+```
+
+**Development Dependencies:**
+Each library defines dev dependencies in `dependency-groups.dev` sections, typically including pytest, ruff, mypy, and library-specific testing tools.
+</dependencies_and_installation>
+
+<testing_instructions>
+The repository uses **pytest** as the testing framework with consistent configuration across all libraries:
+
+**Running Tests:**
+```bash
+make test                    # Run all tests in current library
+TEST=path/to/test.py make test  # Run specific test file
+```
+
+**Key Testing Features:**
+- **asyncio_mode = "auto"** configured in all libraries for seamless async testing
+- **pytest-asyncio**, **pytest-mock**, **pytest-watcher** plugins available
+- **syrupy** for snapshot testing
+- **pytest-cov** for coverage reporting
+
+**Integration Testing:**
+Some libraries require **Docker Compose** for PostgreSQL integration tests:
+- PostgreSQL services defined in `tests/compose-postgres.yml` files
+- Tests automatically start/stop Docker services via Makefile targets
+- Use `NO_DOCKER=true` environment variable to skip Docker-dependent tests
+
+**Test Structure:**
+- Each library has `tests/` directory with `conftest.py` for fixtures
+- Test files follow `test_*.py` naming convention
+- Libraries include both unit tests and integration tests
+- Some libraries have benchmarking capabilities in `bench/` directories
+
+**Coverage:**
+Run `make coverage` in individual libraries to generate coverage reports with pytest-cov.
+</testing_instructions>
 # AGENTS Instructions
 
 This repository is a monorepo. Each library lives in a subdirectory under `libs/`.
@@ -53,3 +165,4 @@ sdk-js (standalone)
 ```
 
 Changes to a library may impact all of its dependents shown above.
+