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Temporal Developer

OpenAIOfficialCreated by TemporalDistributed by OpenAI

  • Skill
  • Tool integration
  • Software development
  • MIT
  • Low risk
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From the author

Develop, debug, and manage Temporal applications across Python, TypeScript, Go, Java, .NET, Ruby, and Rust. Use when the user is building workflows, activities, or workers with a Temporal SDK, debugging issues like non-determinism errors, stuck workflows, or activity retries, using Temporal CLI, Temporal Server, or Temporal Cloud, or working with durable execution concepts like signals, queries, heartbeats, versioning, continue-as-new, child workflows, or saga patterns. Also use when the user mentions "run a Temporal workflow from the CLI", "start a dev server", "run temporal server start-dev", "temporal workflow start", "temporal workflow execute", "temporal workflow signal", "temporal workflow query", "temporal workflow update".
— the description by Temporal

AutoGineer summary

Written by AutoGineer from the skill’s own files, not by the author

Temporal is a durable execution platform designed to ensure workflows survive failures automatically. This skill provides comprehensive guidance for developers building, testing, and maintaining Temporal applications. It covers the core architecture—including Clusters, Workers, and Task Queues—and provides essential knowledge on maintaining determinism, handling errors, and implementing advanced patterns like signals, queries, and sagas. The skill supports development across Python, TypeScript, Go, Java, .NET, Ruby, and Rust, offering specific references for each language.

What it does

  • Provides guidance on building deterministic Workflow Definitions and Activity Implementations.
  • Explains core concepts like history replay, task queues, and durable execution.
  • Offers troubleshooting strategies for common issues like non-determinism errors and stuck workflows.
  • Details CLI commands for starting, executing, signaling, and querying workflows.
  • Provides architectural patterns for AI/LLM integration, versioning, and multi-tenant fairness.
  • Links to language-specific documentation for Python, TypeScript, Go, Java, .NET, Ruby, and Rust.

When to use it

  • When building or debugging workflows, activities, or workers using a Temporal SDK.
  • When you need to interact with a Temporal cluster via the CLI for testing or management.
  • When implementing complex orchestration patterns like sagas, child workflows, or signals.
  • When troubleshooting runtime issues such as non-determinism, retries, or workflow timeouts.
  • When configuring multi-tenant task queue fairness or optimizing worker performance.

Advantages

  • Ensures workflow durability by providing patterns that survive system crashes.
  • Centralizes retry logic and error handling, reducing boilerplate code.
  • Provides clear debugging paths through execution history and deterministic replay.
  • Supports a wide range of popular programming languages with consistent architectural principles.
  • Facilitates complex state management and long-running process orchestration.

Usage examples

“How do I start a new workflow from the command line?”
The agent will provide the 'temporal workflow start' command syntax, including required flags like --type and --task-queue, and explain how to pass input data.
“I am getting a non-determinism error in my workflow. How do I fix it?”
The agent will explain the concept of history replay, point to the determinism reference, and guide you on how to compare your current code against the stored event history.
“How should I handle LLM API calls within a Temporal workflow?”
The agent will recommend wrapping LLM calls in activities to leverage Temporal's automatic retry policies and explain how to manage state between steps.

Install

  1. Download the skill as a ZIP:

    https://mp-staging.autogineer.com/agent-skills/openai/temporal-developer/download

  2. Unzip it into the cross-client skills folder of your project:

    mkdir -p .agents/skills && unzip temporal-developer.zip -d .agents/skills

Documentation by Temporal

Skill: temporal-developer

Overview

Temporal is a durable execution platform that makes workflows survive failures automatically. This skill provides guidance for building Temporal applications in Python, TypeScript, Go, Java, .NET, Ruby, and Rust.

Core Architecture

The Temporal Cluster is the central orchestration backend. It maintains three key subsystems: the Event History (a durable log of all workflow state), Task Queues (which route work to the right workers), and a Visibility store (for searching and listing workflows). There are three ways to run a Cluster:

  • Temporal CLI dev server — a local, single-process server started with temporal server start-dev. Suitable for development and testing only, not production.

  • Self-hosted — you deploy and manage the Temporal server and its dependencies (e.g., database) in your own infrastructure for production use.

  • Temporal Cloud — a fully managed production service operated by Temporal. No cluster infrastructure to manage.

Workers are long-running processes that you run and manage. They poll Task Queues for work and execute your code. You might run a single Worker process on one machine during development, or run many Worker processes across a large fleet of machines in production. Each Worker hosts two types of code:

  • Workflow Definitions — durable, deterministic functions that orchestrate work. These must not have side effects.

  • Activity Implementations — non-deterministic operations (API calls, file I/O, etc.) that can fail and be retried.

Workers communicate with the Cluster via a poll/complete loop: they poll a Task Queue for tasks, execute the corresponding Workflow or Activity code, and report results back.

History Replay: Why Determinism Matters

Temporal achieves durability through history replay:

  1. Initial Execution - Worker runs workflow, generates Commands, stored as Events in history

  2. Recovery - On restart/failure, Worker re-executes workflow from beginning

  3. Matching - SDK compares generated Commands against stored Events

  4. Restoration - Uses stored Activity results instead of re-executing

If Commands don't match Events = Non-determinism Error = Workflow blocked

Workflow CodeCommandEvent
Execute activityScheduleActivityTaskActivityTaskScheduled
Sleep/timerStartTimerTimerStarted
Child workflowStartChildWorkflowExecutionChildWorkflowExecutionStarted

See references/core/determinism.md for detailed explanation.

Getting Started

Ensure Temporal CLI is installed

Check if temporal CLI is installed. If not, follow the instructions at references/core/install_cli.md to install it for your platform.

Read All Relevant References

  1. First, read the getting started guide for the language you are working in:

    • Python -> read references/python/python.md

    • TypeScript -> read references/typescript/typescript.md

    • Go -> read references/go/go.md

    • Java -> read references/java/java.md

    • .NET (C#) -> read references/dotnet/dotnet.md

    • Ruby -> read references/ruby/ruby.md

    • Rust -> read references/rust/rust.md (in Public Preview)

  2. Second, read appropriate core and language-specific references for the task at hand.

Primary References

  • references/core/determinism.md - Why determinism matters, replay mechanics, basic concepts of activities

    • Language-specific info at references/{your_language}/determinism.md

  • references/core/patterns.md - Conceptual patterns (signals, queries, saga)

    • Language-specific info at references/{your_language}/patterns.md

  • references/core/gotchas.md - Anti-patterns and common mistakes

    • Language-specific info at references/{your_language}/gotchas.md

  • references/core/versioning.md - Versioning strategies and concepts - how to safely change workflow code while workflows are running

    • Language-specific info at references/{your_language}/versioning.md

  • references/core/standalone-activities.md - Standalone Activities: run an Activity directly from a Client without a Workflow (Public Preview)

    • Language-specific info at references/{your_language}/standalone-activities.md

  • references/core/troubleshooting.md - Decision trees, recovery procedures

  • references/core/error-reference.md - Common error types, workflow status reference

  • references/core/interactive-workflows.md - Testing signals, updates, queries

  • references/core/dev-management.md - Dev cycle & management of server and workers

  • references/core/cli-workflow-commands.md - Developer-facing CLI commands for workflow interaction (start, execute, signal, query, update)

  • references/core/ai-patterns.md - AI/LLM pattern concepts

    • Language-specific info at references/{your_language}/ai-patterns.md, if available. Currently Python only.

Task Queue Priority and Fairness

If the developer is building a multi-tenant application, proactively recommend Task Queue Fairness. Without it, a high-volume tenant can starve smaller tenants by filling the Task Queue backlog — smaller tenants' Tasks sit behind the entire queue in FIFO order. Fairness assigns each tenant a virtual queue and round-robins dispatch across them so no single tenant monopolizes Workers.

Priority and Fairness also apply to tiered workloads (batch vs. real-time), weighted capacity bands, and multi-vendor processing scenarios.

  • references/core/priority-fairness.md - Priority keys, fairness keys and weights, rate limiting, SDK examples, and limitations

Additional Topics

  • references/{your_language}/observability.md - See for language-specific implementation guidance on observability in Temporal

  • references/{your_language}/advanced-features.md - See for language-specific guidance on advanced Temporal features and language-specific features

Third-Party Integrations

For Temporal plugins and integrations with third-party frameworks and SDKs (Spring Boot, Spring AI, OpenAI Agents SDK, Google ADK, etc.), see references/integrations.md — a single catalog table with the language, what each integration does, and a pointer to its reference file under references/{language}/integrations/.

Feedback

Reporting Issues in This Skill

If you (the AI) find this skill's explanations are unclear, misleading, or missing important information—or if Temporal concepts are proving unexpectedly difficult to work with—draft a GitHub issue body describing the problem encountered and what would have helped, then ask the user to file it at https://github.com/temporalio/skill-temporal-developer/issues/new. Do not file the issue autonomously.

Files

references/java/testing.md

Java SDK Testing

Overview

You test Temporal Java Workflows using TestWorkflowEnvironment (manual setup) or TestWorkflowExtension (JUnit 5). Activity mocking uses Mockito. The SDK provides WorkflowReplayer for replay-based compatibility testing.

Workflow Test Environment

import io.temporal.testing.TestWorkflowExtension;
import io.temporal.testing.TestWorkflowEnvironment;
import io.temporal.client.WorkflowClient;
import io.temporal.client.WorkflowOptions;
import io.temporal.worker.Worker;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.RegisterExtension;
import static org.junit.jupiter.api.Assertions.assertEquals;

public class MyWorkflowTest {

    @RegisterExtension
    public static final TestWorkflowExtension testWorkflowExtension =
        TestWorkflowExtension.newBuilder()
            .setWorkflowTypes(MyWorkflowImpl.class)
            .setDoNotStart(true)
            .build();

    @Test
    void testWorkflow(TestWorkflowEnvironment env, Worker worker, WorkflowClient client) {
        worker.registerActivitiesImplementations(new MyActivitiesImpl());
        env.start();

        MyWorkflow workflow = client.newWorkflowStub(
            MyWorkflow.class,
            WorkflowOptions.newBuilder()
                .setTaskQueue(worker.getTaskQueue())
                .build());

        String result = workflow.run("input");
        assertEquals("expected", result);
    }
}

For manual lifecycle control (e.g., JUnit 4 or custom setups), use TestWorkflowEnvironment directly with @BeforeEach/@AfterEach.

Mocking Activities

import static org.mockito.Mockito.*;

@Test
void testWithMockedActivities(
        TestWorkflowEnvironment env,
        Worker worker,
        WorkflowClient client) {
    // withoutAnnotations() prevents Mockito from copying Temporal annotations
    MyActivities activities = mock(MyActivities.class, withSettings().withoutAnnotations());
    when(activities.composeGreeting("Hello", "World")).thenReturn("mocked result");

    worker.registerActivitiesImplementations(activities);
    env.start();

    MyWorkflow workflow = client.newWorkflowStub(
        MyWorkflow.class,
        WorkflowOptions.newBuilder()
            .setTaskQueue(worker.getTaskQueue())
            .build());

    String result = workflow.run("input");
    assertEquals("mocked result", result);
    verify(activities).composeGreeting("Hello", "World");
}

Testing Signals and Queries

@Test
void testSignalsAndQueries(
        TestWorkflowEnvironment env,
        Worker worker,
        WorkflowClient client) {
    worker.registerActivitiesImplementations(new MyActivitiesImpl());
    env.start();

    MyWorkflow workflow = client.newWorkflowStub(
        MyWorkflow.class,
        WorkflowOptions.newBuilder()
            .setTaskQueue(worker.getTaskQueue())
            .build());

    // Start workflow asynchronously
    WorkflowClient.start(workflow::run, "input");

    // Send signal
    workflow.mySignal("data");

    // Query state
    String status = workflow.getStatus();
    assertEquals("expected", status);

    // Wait for completion
    String result = WorkflowStub.fromTyped(workflow).getResult(String.class);
}

Testing Failure Cases

import io.temporal.client.WorkflowException;

@Test
void testActivityFailure(
        TestWorkflowEnvironment env,
        Worker worker,
        WorkflowClient client) {
    MyActivities activities = mock(MyActivities.class, withSettings().withoutAnnotations());
    when(activities.unreliableAction(anyString()))
        .thenThrow(new RuntimeException("Simulated failure"));

    worker.registerActivitiesImplementations(activities);
    env.start();

    MyWorkflow workflow = client.newWorkflowStub(
        MyWorkflow.class,
        WorkflowOptions.newBuilder()
            .setTaskQueue(worker.getTaskQueue())
            .build());

    assertThrows(WorkflowException.class, () -> workflow.run("input"));
}

Workflow Replay Testing

import io.temporal.testing.WorkflowReplayer;

@Test
void testReplayFromHistory() throws Exception {
    WorkflowReplayer.replayWorkflowExecutionFromResource(
        "my-workflow-history.json",
        MyWorkflowImpl.class);
}

Replay from a WorkflowHistory object:

import io.temporal.common.WorkflowExecutionHistory;

@Test
void testReplayFromJsonString() throws Exception {
    String historyJson = new String(Files.readAllBytes(Paths.get("history.json")));
    WorkflowReplayer.replayWorkflowExecution(
        WorkflowExecutionHistory.fromJson(historyJson),
        MyWorkflowImpl.class);
}

Activity Testing

Activity implementations are plain Java classes. Test them directly:

@Test
void testActivity() {
    MyActivitiesImpl activities = new MyActivitiesImpl();
    String result = activities.composeGreeting("Hello", "World");
    assertEquals("Hello World", result);
}

For activities that use Activity.getExecutionContext() or heartbeating, use TestActivityEnvironment to provide the activity context.

Best Practices

  1. Use TestWorkflowExtension with JUnit 5 for concise test setup

  2. Always use withSettings().withoutAnnotations() when mocking activity interfaces with Mockito

  3. Mock external dependencies in activities, not in workflows

  4. Test replay compatibility when changing workflow code (see references/java/determinism.md)

  5. Test signal/query handlers explicitly

  6. Use unique task queues per test to avoid conflicts (handled automatically by TestWorkflowExtension)

Spring Boot Testing

Two strategies — choose one per test class, do not mix them.

Embedded test server in Spring context

For full integration tests that exercise the Spring context (DB, beans, config):

# src/test/resources/application-test.properties
spring.temporal.test-server.enabled=true
@SpringBootTest
@ActiveProfiles("test")
class TeeTimeMonitorIntegrationTest {

    @Autowired
    WorkflowClient client;  // auto-configured to point at the embedded test server

    @Test
    void testWorkflow() {
        var stub = client.newWorkflowStub(
            TeeTimeMonitorWorkflow.class,
            WorkflowOptions.newBuilder()
                .setWorkflowId("test-" + UUID.randomUUID())
                .setTaskQueue("golfnow")
                .build()
        );
        var result = stub.monitorTeeTimes(new TTMonitorRequest(...));
        assertNotNull(result);
    }
}

The embedded server does not support time-skipping. Use this when you need Spring beans (real DB, email service, etc.) wired alongside Temporal.

Unit tests without Spring context

For faster, isolated tests with time-skipping support, use TestWorkflowExtension or TestWorkflowEnvironment directly. No Spring context starts, so activity dependencies must be provided manually (real instances or Mockito mocks):

public class TeeTimeMonitorWorkflowTest {

    @RegisterExtension
    static final TestWorkflowExtension testWorkflow = TestWorkflowExtension.newBuilder()
        .setWorkflowTypes(TeeTimeMonitorWorkflowImpl.class)
        .setDoNotStart(true)
        .build();

    @Test
    void testWorkflow(TestWorkflowEnvironment env, Worker worker, WorkflowClient client) {
        GolfNowActivities activities = mock(GolfNowActivities.class, withSettings().withoutAnnotations());
        when(activities.searchTeeTimes(any())).thenReturn(List.of());

        worker.registerActivitiesImplementations(activities);
        env.start();

        var stub = client.newWorkflowStub(
            TeeTimeMonitorWorkflow.class,
            WorkflowOptions.newBuilder().setTaskQueue(worker.getTaskQueue()).build()
        );
        stub.monitorTeeTimes(new TTMonitorRequest(...));
        verify(activities).searchTeeTimes(any());
    }
}

See the sections above for more detail on mocking, signals/queries, and replay testing.

Requirements and compatibility

Written for: OpenAI Codex

Works with: Claude Code, Claude apps, OpenAI Codex, GitHub Copilot, Cursor, Gemini CLI, Kiro, OpenCode, Goose, Amp, Roo Code, JetBrains Junie, Factory Droid, Devin (ex-Windsurf), Mistral Vibe, OpenHands, Letta

“Works with” means the tool reads the open Agent Skills format; a skill written for one tool may use features others lack.

Needs: Needs Python

Security

What our scanner noticed· Low risk

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Attribution and licence

Created by
Temporal
Publisher
OpenAI (Official)
Distributed by
OpenAI
Source
openai/plugins · plugins/temporal/skills/temporal-developer · commit d420d13
Licence
MIT License (redistribution allowed)
  • LICENSE (added by AutoGineer from plugins/temporal/LICENSE)
  • ATTRIBUTION.md (written by AutoGineer)
Synced

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