LangGraph plugin samples by DABH · Pull Request #289 · temporalio/samples-python

DABH · 2026-04-14T23:09:55Z

Summary

Add samples demonstrating the Temporal LangGraph plugin, which runs LangGraph workflows as durable Temporal workflows. Each graph node or @task executes as a Temporal activity with automatic retries, timeouts, and crash recovery.

Samples are provided for both the Graph API (declarative StateGraph with nodes and edges) and the Functional API (imperative @task / @entrypoint decorators).

Sample	Graph API	Functional API	Description
Hello World	✅	✅	Minimal sample — single node/task that processes a query string. Start here.
Human-in-the-loop	✅	✅	Chatbot that uses `interrupt()` to pause for human approval, Temporal signals to receive feedback, and queries to expose the pending draft.
Continue-as-new	✅	✅	Multi-stage data pipeline that uses `continue-as-new` with task result caching so previously-completed stages are not re-executed.
ReAct Agent	✅	✅	Tool-calling agent loop. Graph API uses `add_conditional_edges`; Functional API uses a `while` loop.
Control Flow	—	✅	Parallel task execution, `for` loops, and `if/else` branching — patterns that are natural in the Functional API.
LangSmith Tracing	✅	✅	Combines `LangGraphPlugin` with Temporal's `LangSmithPlugin` for durable execution + full LLM observability. Requires API keys.

Key Features Demonstrated

Durable execution — Every graph node / @task runs as a Temporal activity with configurable timeouts and retry policies.
Human-in-the-loop — LangGraph's interrupt() pauses the graph; Temporal signals deliver human input; queries expose pending state to UIs.
Continue-as-new with caching — get_cache() captures completed task results; passing the cache to the next execution avoids re-running them.
Conditional routing — Graph API's add_conditional_edges and Functional API's native if/else/while for agent loops.
Parallel execution — Functional API launches multiple tasks concurrently by creating futures before awaiting them.
LangSmith observability — LangSmithPlugin on the client + LangGraphPlugin on the worker for full trace propagation through Temporal workflows.

Related PRs

SDK: AI-36: Add LangGraph plugin sdk-python#1448
Supersedes: LangGraph Samples #272

Test plan

Samples are not runnable until the SDK PR lands; verify after merge of AI-36: Add LangGraph plugin sdk-python#1448
Run each sample with uv run langgraph_plugin/<api>/<sample>/run_worker.py + run_workflow.py
LangSmith tracing samples require ANTHROPIC_API_KEY and LANGCHAIN_API_KEY

Seven samples demonstrating the Temporal LangGraph plugin across both the Graph API and Functional API: - Human-in-the-loop: interrupt() + Temporal signals for chatbot approval - Continue-as-new: task result caching across workflow boundaries - ReAct agent: tool-calling loop with conditional edges / while loop - Control flow (Functional API only): parallel, for-loop, if/else Related SDK PR: temporalio/sdk-python#1448

CLAassistant · 2026-04-14T23:10:01Z

All committers have signed the CLA.

CLAassistant · 2026-04-14T23:10:03Z

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… merge) so that CI otherwise passes

Copilot

Pull request overview

Adds a new langgraph_plugin/ sample suite to demonstrate running LangGraph workflows as durable Temporal workflows via the Temporal LangGraph plugin, covering both LangGraph Graph API and Functional API patterns.

Changes:

Introduces 7 new LangGraph+Temporal sample workflows (human-in-the-loop, continue-as-new w/ caching, ReAct agent, control-flow).
Adds a new langgraph dependency group and includes langgraph_plugin in the build packages list.
Updates repository documentation to link to the new sample suite and provides a dedicated README for running the samples.

Reviewed changes

Copilot reviewed 24 out of 34 changed files in this pull request and generated 6 comments.

Show a summary per file

File	Description
pyproject.toml	Adds `langgraph` dependency group, includes `langgraph_plugin` in wheel packages, adjusts lint/test tasks, and adds mypy override.
README.md	Links the new `langgraph_plugin` samples from the repo root README.
langgraph_plugin/README.md	Adds usage documentation and a sample matrix for the new suite.
langgraph_plugin/init.py	Declares the new top-level sample package.
langgraph_plugin/graph_api/init.py	Declares Graph API samples namespace.
langgraph_plugin/graph_api/react_agent/init.py	Declares Graph API ReAct agent package.
langgraph_plugin/graph_api/react_agent/workflow.py	Implements Graph API ReAct agent workflow and graph definition.
langgraph_plugin/graph_api/react_agent/run_worker.py	Worker wiring for Graph API ReAct agent sample.
langgraph_plugin/graph_api/react_agent/run_workflow.py	Starter script for Graph API ReAct agent sample.
langgraph_plugin/graph_api/human_in_the_loop/init.py	Declares Graph API human-in-the-loop package.
langgraph_plugin/graph_api/human_in_the_loop/workflow.py	Implements Graph API interrupt + Temporal signal/query human approval flow.
langgraph_plugin/graph_api/human_in_the_loop/run_worker.py	Worker wiring for Graph API human-in-the-loop sample.
langgraph_plugin/graph_api/human_in_the_loop/run_workflow.py	Starter script for Graph API human-in-the-loop sample.
langgraph_plugin/graph_api/continue_as_new/init.py	Declares Graph API continue-as-new package.
langgraph_plugin/graph_api/continue_as_new/workflow.py	Implements Graph API pipeline w/ continue-as-new + cache handoff.
langgraph_plugin/graph_api/continue_as_new/run_worker.py	Worker wiring for Graph API continue-as-new sample.
langgraph_plugin/graph_api/continue_as_new/run_workflow.py	Starter script for Graph API continue-as-new sample.
langgraph_plugin/functional_api/init.py	Declares Functional API samples namespace.
langgraph_plugin/functional_api/react_agent/init.py	Declares Functional API ReAct agent package.
langgraph_plugin/functional_api/react_agent/workflow.py	Implements Functional API ReAct agent via `@task` + `@entrypoint`.
langgraph_plugin/functional_api/react_agent/run_worker.py	Worker wiring for Functional API ReAct agent sample.
langgraph_plugin/functional_api/react_agent/run_workflow.py	Starter script for Functional API ReAct agent sample.
langgraph_plugin/functional_api/human_in_the_loop/init.py	Declares Functional API human-in-the-loop package.
langgraph_plugin/functional_api/human_in_the_loop/workflow.py	Implements Functional API interrupt + signal/query human approval flow.
langgraph_plugin/functional_api/human_in_the_loop/run_worker.py	Worker wiring for Functional API human-in-the-loop sample.
langgraph_plugin/functional_api/human_in_the_loop/run_workflow.py	Starter script for Functional API human-in-the-loop sample.
langgraph_plugin/functional_api/control_flow/init.py	Declares Functional API control-flow package.
langgraph_plugin/functional_api/control_flow/workflow.py	Implements Functional API sample demonstrating parallelism + branching.
langgraph_plugin/functional_api/control_flow/run_worker.py	Worker wiring for Functional API control-flow sample.
langgraph_plugin/functional_api/control_flow/run_workflow.py	Starter script for Functional API control-flow sample.
langgraph_plugin/functional_api/continue_as_new/init.py	Declares Functional API continue-as-new package.
langgraph_plugin/functional_api/continue_as_new/workflow.py	Implements Functional API pipeline w/ continue-as-new + cache handoff.
langgraph_plugin/functional_api/continue_as_new/run_worker.py	Worker wiring for Functional API continue-as-new sample.
langgraph_plugin/functional_api/continue_as_new/run_workflow.py	Starter script for Functional API continue-as-new sample.

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…gs, and configurable client

Combines LangGraphPlugin (durable execution) with LangSmithPlugin (observability) for full tracing of LLM calls through Temporal workflows.

brianstrauch · 2026-04-15T19:36:02Z

@@ -0,0 +1,41 @@
+# LangSmith Tracing (Functional API)
+
+Same pattern as the Graph API version, using `@task` and `@entrypoint` decorators.


I assume people are either using Graph API or Functional API and not both. If that's true, we should probably avoid referencing one from the other since a user of the Functional API probably doesn't care about looking at Graph API examples.

brianstrauch · 2026-04-15T19:44:39Z

+# Terminal 1
+uv run langgraph_plugin/functional_api/langsmith_tracing/run_worker.py
+
+# Terminal 2
+uv run langgraph_plugin/functional_api/langsmith_tracing/run_workflow.py


Do we want to get in the habit of running these in the same python file to reduce the number of steps needed to get started?

brianstrauch · 2026-04-15T19:45:20Z

+|------|-------------|
+| `workflow.py` | `@traceable` chat task, `@entrypoint`, and `ChatFunctionalWorkflow` |
+| `run_worker.py` | Creates client with `LangSmithPlugin`, worker with `LangGraphPlugin` |
+| `run_workflow.py` | Creates client with `LangSmithPlugin`, executes workflow |


workflow -> Workflow

brianstrauch · 2026-04-15T19:47:50Z

+
+from datetime import timedelta
+
+from langgraph.func import entrypoint as lg_entrypoint


This naming collision is a bit of a pain point that comes up 100% of the time when using the Functional API. I wonder if we want our plugin to provide temporal_entrypoint and temporal_graph to avoid this issue.

brianstrauch · 2026-04-15T19:49:32Z

+
+
+@task
+@traceable(name="chat_task", run_type="chain")


We should also demonstrate wrapping traceables around functions inside the task/Activity and around functions inside the entrypoint/Workflow. Right now we're only covering 1/3 use cases.

brianstrauch · 2026-04-15T19:50:24Z

+    t.func.__name__: {"start_to_close_timeout": timedelta(seconds=30)}
+    for t in all_tasks


for loop not needed since there's only one task

brianstrauch · 2026-04-15T19:51:02Z

+
+## Running the Sample
+
+Prerequisites: `uv sync --group langgraph` and a running Temporal dev server.


Type out temporal server start-dev here?

brianstrauch · 2026-04-15T19:54:01Z

+
+## What This Sample Demonstrates
+
+- Task result caching across continue-as-new boundaries with `get_cache()`


Rename to cache() to match graph() and entrypoint()

brianstrauch · 2026-04-15T19:55:16Z

+
+## How It Works
+
+1. Three tasks run sequentially: `extract` (x2) -> `transform` (+50) -> `load` (x3).


This is a bit weird. My first thought is why is a x2 operation called "extract"? Maybe we want to rename it or actually do an ETL-like pipeline

DABH requested a review from a team as a code owner April 14, 2026 23:09

DABH requested review from brianstrauch and Copilot April 14, 2026 23:16

Copilot started reviewing on behalf of DABH April 14, 2026 23:16 View session

DABH added 2 commits April 14, 2026 18:17

Remove explicit langchain deps from langgraph group to avoid conflict

8a260c6

Declare langchain and langgraph as conflicting dependency groups

042a51f

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DABH added 2 commits April 14, 2026 18:22

Fix import sorting and formatting

3e7f91b

Update dependencies and lint config (temporarily - waiting for SDK PR…

0505fd1

… merge) so that CI otherwise passes

DABH force-pushed the langgraph-samples branch from 0256bd3 to 0505fd1 Compare April 15, 2026 00:38

DABH requested a review from Copilot April 15, 2026 00:40

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DABH added 3 commits April 14, 2026 21:21

Add hello_world samples, per-sample READMEs, tests, __init__ docstrin…

ee781cd

…gs, and configurable client

Address review: consistent v2 API, unique thread_id, SDK prereq note

e2832bb

Remove SDK prereq note - PR won't merge until plugin is released

f3fb15c

DABH mentioned this pull request Apr 15, 2026

LangGraph Samples #272

Closed

Add LangSmith tracing sample (Graph API + Functional API)

67d1310

Combines LangGraphPlugin (durable execution) with LangSmithPlugin (observability) for full tracing of LLM calls through Temporal workflows.

brianstrauch reviewed Apr 15, 2026

View reviewed changes

DABH mentioned this pull request Apr 16, 2026

Add LangGraph integration documentation temporalio/documentation#4442

Draft

5 tasks

		@@ -0,0 +1,41 @@
		# LangSmith Tracing (Functional API)

		Same pattern as the Graph API version, using `@task` and `@entrypoint` decorators.


		from datetime import timedelta

		from langgraph.func import entrypoint as lg_entrypoint

		t.func.__name__: {"start_to_close_timeout": timedelta(seconds=30)}
		for t in all_tasks


		## Running the Sample

		Prerequisites: `uv sync --group langgraph` and a running Temporal dev server.


		## What This Sample Demonstrates

		- Task result caching across continue-as-new boundaries with `get_cache()`


		## How It Works

		1. Three tasks run sequentially: `extract` (x2) -> `transform` (+50) -> `load` (x3).



		@task
		@traceable(name="chat_task", run_type="chain")

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DABH commented Apr 14, 2026 •

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