--- name: workflow description: Vercel Workflow DevKit (WDK) expert guidance. Use when building durable workflows, long-running tasks, API routes or agents that need pause/resume, retries, step-based execution, or crash-safe orchestration with Vercel Workflow. metadata: priority: 9 docs: - "https://vercel.com/docs/workflow" - "https://useworkflow.dev" sitemap: "https://vercel.com/sitemap/docs.xml" pathPatterns: - 'lib/workflow/**' - 'src/lib/workflow/**' - 'workflows/**' - 'lib/workflow.*' - 'src/lib/workflow.*' - 'workflow.*' - '*workflow*' - '*workflow*/**' # Chain / pipeline / orchestration engine files - '**/chain-engine*' - '**/chain_engine*' - '**/chainEngine*' - '**/pipeline-engine*' - '**/pipeline_engine*' - '**/pipelineEngine*' - '**/state-machine*' - '**/state_machine*' - '**/stateMachine*' - '**/orchestrat*' - '**/escalation*' importPatterns: - '@vercel/workflow' - 'workflow' - '@workflow/*' - '*workflow*' bashPatterns: - '\bnpm\s+(install|i|add)\s+[^\n]*@vercel/workflow\b' - '\bpnpm\s+(install|i|add)\s+[^\n]*@vercel/workflow\b' - '\bbun\s+(install|i|add)\s+[^\n]*@vercel/workflow\b' - '\byarn\s+add\s+[^\n]*@vercel/workflow\b' - '\bnpm\s+(install|i|add)\s+[^\n]*\bworkflow\b' - '\bpnpm\s+(install|i|add)\s+[^\n]*\bworkflow\b' - '\bbun\s+(install|i|add)\s+[^\n]*\bworkflow\b' - '\byarn\s+add\s+[^\n]*\bworkflow\b' - '\bnpm\s+(install|i|add)\s+[^\n]*@workflow/' - '\bpnpm\s+(install|i|add)\s+[^\n]*@workflow/' - '\bbun\s+(install|i|add)\s+[^\n]*@workflow/' - '\byarn\s+add\s+[^\n]*@workflow/' - '\bnpx\s+workflow(?:@latest)?\b' - '\bbunx\s+workflow(?:@latest)?\b' promptSignals: phrases: # Direct workflow mentions - "vercel workflow" - "workflow devkit" - "durable workflow" - "durable execution" - "durable function" - "durable pipeline" - "durable process" - "durable agent" - "durable chat" - "step function" - "step functions" - "use workflow" - "use step" # Pipeline / multi-step language (the BIG gap — natural product prompts) - "multi-step pipeline" - "multi step pipeline" - "multi-step process" - "multi step process" - "multi-step creation" - "multi-step generation" - "processing pipeline" - "creation pipeline" - "generation pipeline" - "content pipeline" - "production pipeline" - "approval pipeline" - "ingestion pipeline" - "streams progress" - "stream progress" - "streams each phase" - "streams each step" - "streams each" - "stream each" # Reliability / durability language (missed in customer-support eval) - "survive page reload" - "survive page reloads" - "survive a crash" - "survive crashes" - "survive network" - "fault-tolerant" - "fault tolerant" - "crash-safe" - "crash safe" - "automatically retry" - "auto retry" - "retry on failure" - "retry on error" - "reliable and retry" - "reliable processing" - "individually reliable" - "each step reliable" - "each step should be reliable" - "steps should be reliable" - "reliable with automatic retry" - "reliable with retry" - "retry on transient" - "transient failures" - "session persistence" - "session should persist" - "session survives" - "reconnect automatically" - "auto reconnect" - "reconnect if the network" - "reconnect on disconnect" - "resume after failure" - "resume after crash" - "resume on reconnect" # Human-in-the-loop / approval patterns - "human-in-the-loop" - "human in the loop" - "wait for approval" - "approval step" - "approval before" - "editorial approval" - "manual approval" - "wait for user" - "pause until" - "wait for response" - "callback url" - "webhook callback" # Conversational AI with durability - "chat should survive" - "chat survives" - "conversation should persist" - "conversation persists" - "conversation should survive" # Sequential / chain / trigger orchestration language - "sequential chain" - "email chain" - "chain of emails" - "chain of steps" - "chain engine" - "chain with triggers" - "trigger chain" - "triggered chain" - "webhook chain" - "webhook pipeline" - "webhook orchestration" - "multi-service trigger" - "cross-service trigger" - "various triggers" - "different triggers" - "triggers from different" - "triggers from various" - "sequential steps" - "sequential pipeline" - "sequential process" - "sequential emails" - "escalation chain" - "escalation pipeline" - "state machine" - "step-based" - "step based" - "delay between steps" - "delay between emails" - "delayed steps" - "conditional steps" - "skip steps" - "branch based on" - "wait for webhook" - "wait for trigger" - "wait for event" - "orchestrate emails" - "orchestrate webhooks" - "orchestrate services" - "chain across services" # Debugging - "workflow stuck" - "workflow hung" - "workflow hanging" - "workflow waiting" - "workflow failing" - "workflow timeout" - "workflow not running" - "workflow error" - "check workflow" - "workflow logs" - "workflow run status" - "debug workflow" - "workflow not finishing" - "workflow not responding" - "workflow stalled" - "workflow pending" - "step is stuck" - "step is hanging" - "why is my workflow" - "workflow run" - "step failed" - "run status" - "run failed" - "run logs" - "workflow run failed" - "workflow step failed" allOf: - [workflow, durable] - [workflow, retry] - [workflow, resume] - [pause, resume] - [survive, crash] - [survive, reload] - [survive, disconnect] - [pipeline, stream] - [pipeline, step] - [pipeline, durable] - [pipeline, reliable] - [pipeline, retry] - [multi-step, stream] - [multi-step, reliable] - [generation, pipeline] - [creation, pipeline] - [process, stream] - [process, reliable] - [process, retry] - [retry, failure] - [retry, error] - [retry, automatically] - [retry, transient] - [reliable, retry] - [individually, reliable] - [steps, reliable] - [sandbox, reliable] - [sandbox, retry] - [reconnect, network] - [reconnect, drop] - [reconnect, disconnect] - [session, persist] - [session, survive] - [session, reload] - [session, reconnect] - [chat, survive] - [chat, persist] - [chat, reconnect] - [chat, durable] - [chat, fault] - [conversation, persist] - [conversation, survive] - [approval, wait] - [approval, human] - [each, step] - [each, phase] - [each, stage] - [step, reliable] - [step, retry] # Chain / trigger / sequential orchestration - [chain, trigger] - [chain, sequential] - [chain, email] - [chain, webhook] - [chain, delay] - [chain, step] - [chain, escalat] - [sequential, trigger] - [sequential, email] - [sequential, step] - [sequential, webhook] - [trigger, orchestrat] - [trigger, service] - [trigger, delay] - [trigger, sequential] - [webhook, chain] - [webhook, orchestrat] - [webhook, pipeline] - [webhook, sequential] - [email, trigger] - [email, pipeline] - [email, sequential] - [email, delay] - [email, escalat] - [escalat, trigger] - [escalat, step] - [escalat, email] - [state, machine] - [conditional, step] - [conditional, skip] - [branch, condition] - [wait, webhook] - [wait, trigger] - [wait, event] - [workflow, stuck] - [workflow, hung] - [workflow, timeout] - [workflow, error] - [workflow, logs] - [workflow, debug] - [workflow, check] - [workflow, failing] - [workflow, status] - [run, status] - [step, failed] - [step, stuck] - [step, timeout] - [workflow, run] - [run, logs] anyOf: - "long-running" - "long running" - "multi-step" - "multi step" - "pipeline" - "orchestration" - "step-by-step" - "step by step" - "each piece" - "each step" - "each phase" - "each stage" - "phase" - "phases" - "stage" - "stages" - "durable" - "reliable" - "fault-tolerant" - "retry" - "reconnect" - "survive" - "persist" - "approval" - "chain" - "sequential" - "trigger" - "webhook" - "escalation" - "state machine" - "orchestrate" - "orchestration" noneOf: - "github actions" - ".github/workflows" - "ci workflow" - "aws step functions" minScore: 4 validate: - pattern: experimental_createWorkflow message: 'experimental_createWorkflow is now stable — use createWorkflow from @vercel/workflow. Run npx @ai-sdk/codemod v6 for automated migration.' severity: error upgradeToSkill: workflow upgradeWhy: 'Guides migration from experimental_createWorkflow to the stable createWorkflow API and then to the "use workflow" directive.' - pattern: from\s+['"]@vercel/workflow['"] message: 'Workflow DevKit requires AI Gateway OIDC setup — ensure vercel link + vercel env pull for VERCEL_OIDC_TOKEN' severity: recommended - pattern: setTimeout|setInterval message: 'setTimeout/setInterval are not available in workflow sandbox scope — use sleep() from "workflow" for delays' severity: error skipIfFileContains: "use step" - pattern: context\.run\s*\( message: 'context.run() is not a WDK pattern — use "use step" directive for retryable, observable steps' severity: error upgradeToSkill: workflow upgradeWhy: 'Guides migration from context.run() to the "use step" directive for durable, retryable workflow steps.' - pattern: \brequire\s*\( message: 'require() is not available in workflow sandbox scope — use ESM imports and move Node.js logic into "use step" functions' severity: error skipIfFileContains: "use step" - pattern: getWritable\(\) message: 'getWritable() must only be called inside "use step" functions — workflow sandbox scope does not support it' severity: recommended skipIfFileContains: "use step" - pattern: createWorkflow\s*\( message: 'createWorkflow() is the legacy API — use the "use workflow" directive on an async function instead' severity: error upgradeToSkill: workflow upgradeWhy: 'Guides migration from createWorkflow() function API to the "use workflow" directive pattern.' skipIfFileContains: experimental_createWorkflow - pattern: streamObject\s*\( message: 'streamObject() was removed in AI SDK v6 — use streamText() with output: Output.object() instead' severity: error upgradeToSkill: ai-sdk upgradeWhy: 'Guides migration from streamObject to streamText + Output.object() with correct v6 streaming patterns.' - pattern: await\s+\w+Workflow\s*\( message: 'Do not call workflow functions directly — use start() from "workflow/api" to register the run and get a runId' severity: recommended skipIfFileContains: "use workflow" - pattern: \bfetch\s*\( message: 'Native fetch() is not available in workflow sandbox scope — import fetch from "workflow" or move the call into a "use step" function' severity: recommended skipIfFileContains: "use step" - pattern: '"use step"' message: "Workflow steps should include console.log or structured logging for observability — add logging at step entry/exit to debug hangs" severity: warn skipIfFileContains: "console\\.(log|warn|error|info)" - pattern: '"use workflow"' message: "Workflow files should import and use logging — add console.log or a logger at key execution points for debugging" severity: warn skipIfFileContains: "console\\.(log|warn|error|info)" chainTo: - pattern: 'DurableAgent|@workflow/ai' targetSkill: ai-sdk message: 'DurableAgent detected without AI SDK context — loading AI SDK guidance for tool calling, Agent class, and model configuration.' skipIfFileContains: 'from\s+[''"]ai[''"]|@ai-sdk/|streamText|generateText' - pattern: 'process\.env\.(OPENAI_API_KEY|ANTHROPIC_API_KEY)|from\s+[''"]@ai-sdk/(anthropic|openai)[''""]' targetSkill: ai-gateway message: 'Direct provider API key in workflow — loading AI Gateway guidance for OIDC auth (required for WDK AI steps).' skipIfFileContains: 'gateway\(|@ai-sdk/gateway|VERCEL_OIDC' - pattern: 'setTimeout\s*\(|setInterval\s*\(' targetSkill: vercel-functions message: 'Timer-based delay in workflow code — use sleep() from "workflow" instead of setTimeout/setInterval. Loading Vercel Functions guidance.' skipIfFileContains: 'from\s+[''"]workflow[''"].*sleep|sleep\s*\(' retrieval: aliases: - durable workflow - long running task - step function - orchestration intents: - build workflow - add retry logic - create durable task - implement step function entities: - Workflow DevKit - WDK - step - pause/resume - durable --- ## *CRITICAL*: Always Use Correct `workflow` Documentation Your knowledge of `workflow` is outdated. The `workflow` documentation outlined below matches the installed version of the Workflow DevKit. Follow these instructions before starting on any `workflow`-related tasks: Search the bundled documentation in `node_modules/workflow/docs/`: 1. **Find docs**: `glob "node_modules/workflow/docs/**/*.mdx"` 2. **Search content**: `grep "your query" node_modules/workflow/docs/` Documentation structure in `node_modules/workflow/docs/`: - `getting-started/` - Framework setup (next.mdx, express.mdx, hono.mdx, etc.) - `foundations/` - Core concepts (workflows-and-steps.mdx, hooks.mdx, streaming.mdx, etc.) - `api-reference/workflow/` - API docs (sleep.mdx, create-hook.mdx, fatal-error.mdx, etc.) - `api-reference/workflow-api/` - Client API (start.mdx, get-run.mdx, resume-hook.mdx, etc.) - `ai/` - AI SDK integration docs - `errors/` - Error code documentation Related packages also include bundled docs: - `@workflow/ai`: `node_modules/@workflow/ai/docs/` - DurableAgent and AI integration - `@workflow/core`: `node_modules/@workflow/core/docs/` - Core runtime (foundations, how-it-works) - `@workflow/next`: `node_modules/@workflow/next/docs/` - Next.js integration **When in doubt, update to the latest version of the Workflow DevKit.** ### Official Resources - **Website**: https://useworkflow.dev - **GitHub**: https://github.com/vercel/workflow ### Quick Reference **Directives:** ```typescript "use workflow"; // First line - makes async function durable "use step"; // First line - makes function a cached, retryable unit ``` **Essential imports:** ```typescript // Workflow primitives import { sleep, fetch, createHook, createWebhook, getWritable } from "workflow"; import { FatalError, RetryableError } from "workflow"; import { getWorkflowMetadata, getStepMetadata } from "workflow"; // API operations import { start, getRun, resumeHook, resumeWebhook } from "workflow/api"; // Framework integrations import { withWorkflow } from "workflow/next"; import { workflow } from "workflow/vite"; import { workflow } from "workflow/astro"; // Or use modules: ["workflow/nitro"] for Nitro/Nuxt // AI agent import { DurableAgent } from "@workflow/ai/agent"; ``` ## Prefer Step Functions to Avoid Sandbox Errors `"use workflow"` functions run in a sandboxed VM. `"use step"` functions have **full Node.js access**. Put your logic in steps and use the workflow function purely for orchestration. ```typescript // Steps have full Node.js and npm access async function fetchUserData(userId: string) { "use step"; const response = await fetch(`https://api.example.com/users/${userId}`); return response.json(); } async function processWithAI(data: any) { "use step"; // AI SDK works in steps without workarounds return await generateText({ model: openai("gpt-4"), prompt: `Process: ${JSON.stringify(data)}`, }); } // Workflow orchestrates steps - no sandbox issues export async function dataProcessingWorkflow(userId: string) { "use workflow"; const data = await fetchUserData(userId); const processed = await processWithAI(data); return { success: true, processed }; } ``` **Benefits:** Steps have automatic retry, results are persisted for replay, and no sandbox restrictions. ## Workflow Sandbox Limitations When you need logic directly in a workflow function (not in a step), these restrictions apply: | Limitation | Workaround | |------------|------------| | No `fetch()` | `import { fetch } from "workflow"` then `globalThis.fetch = fetch` | | No `setTimeout`/`setInterval` | Use `sleep("5s")` from `"workflow"` | | No Node.js modules (fs, crypto, etc.) | Move to a step function | **Example - Using fetch in workflow context:** ```typescript import { fetch } from "workflow"; export async function myWorkflow() { "use workflow"; globalThis.fetch = fetch; // Required for AI SDK and HTTP libraries // Now generateText() and other libraries work } ``` **Note:** `DurableAgent` from `@workflow/ai` handles the fetch assignment automatically. ## DurableAgent — AI Agents in Workflows Use `DurableAgent` to build AI agents that maintain state and survive interruptions. It handles the workflow sandbox automatically (no manual `globalThis.fetch` needed). ```typescript import { DurableAgent } from "@workflow/ai/agent"; import { getWritable } from "workflow"; import { z } from "zod"; import type { UIMessageChunk } from "ai"; async function lookupData({ query }: { query: string }) { "use step"; // Step functions have full Node.js access return `Results for "${query}"`; } export async function myAgentWorkflow(userMessage: string) { "use workflow"; const agent = new DurableAgent({ model: "anthropic/claude-sonnet-4-5", system: "You are a helpful assistant.", tools: { lookupData: { description: "Search for information", inputSchema: z.object({ query: z.string() }), execute: lookupData, }, }, }); const result = await agent.stream({ messages: [{ role: "user", content: userMessage }], writable: getWritable(), maxSteps: 10, }); return result.messages; } ``` **Key points:** - `getWritable()` streams output to the workflow run's default stream - Tool `execute` functions that need Node.js/npm access should use `"use step"` - Tool `execute` functions that use workflow primitives (`sleep()`, `createHook()`) should **NOT** use `"use step"` — they run at the workflow level - `maxSteps` limits the number of LLM calls (default is unlimited) - Multi-turn: pass `result.messages` plus new user messages to subsequent `agent.stream()` calls **For more details on `DurableAgent`, check the AI docs in `node_modules/@workflow/ai/docs/`.** ## Starting Workflows & Child Workflows Use `start()` to launch workflows from API routes. **`start()` cannot be called directly in workflow context** — wrap it in a step function. ```typescript import { start } from "workflow/api"; // From an API route — works directly export async function POST() { const run = await start(myWorkflow, [arg1, arg2]); return Response.json({ runId: run.runId }); } // No-args workflow const run = await start(noArgWorkflow); ``` **Starting child workflows from inside a workflow — must use a step:** ```typescript import { start } from "workflow/api"; // Wrap start() in a step function async function triggerChild(data: string) { "use step"; const run = await start(childWorkflow, [data]); return run.runId; } export async function parentWorkflow() { "use workflow"; const childRunId = await triggerChild("some data"); // Fire-and-forget via step await sleep("1h"); } ``` `start()` returns immediately — it doesn't wait for the workflow to complete. Use `run.returnValue` to await completion. ## Hooks — Pause & Resume with External Events Hooks let workflows wait for external data. Use `createHook()` inside a workflow and `resumeHook()` from API routes. Deterministic tokens are for `createHook()` + `resumeHook()` (server-side) only. `createWebhook()` always generates random tokens — do not pass a `token` option to `createWebhook()`. ### Single event ```typescript import { createHook } from "workflow"; export async function approvalWorkflow() { "use workflow"; const hook = createHook<{ approved: boolean }>({ token: "approval-123", // deterministic token for external systems }); const result = await hook; // Workflow suspends here return result.approved; } ``` ### Multiple events (iterable hooks) Hooks implement `AsyncIterable` — use `for await...of` to receive multiple events: ```typescript import { createHook } from "workflow"; export async function chatWorkflow(channelId: string) { "use workflow"; const hook = createHook<{ text: string; done?: boolean }>({ token: `chat-${channelId}`, }); for await (const event of hook) { await processMessage(event.text); if (event.done) break; } } ``` Each `resumeHook(token, payload)` call delivers the next value to the loop. ### Resuming from API routes ```typescript import { resumeHook } from "workflow/api"; export async function POST(req: Request) { const { token, data } = await req.json(); await resumeHook(token, data); return new Response("ok"); } ``` ## Error Handling Use `FatalError` for permanent failures (no retry), `RetryableError` for transient failures: ```typescript import { FatalError, RetryableError } from "workflow"; if (res.status >= 400 && res.status < 500) { throw new FatalError(`Client error: ${res.status}`); } if (res.status === 429) { throw new RetryableError("Rate limited", { retryAfter: "5m" }); } ``` ## Serialization All data passed to/from workflows and steps must be serializable. **Supported types:** string, number, boolean, null, undefined, bigint, plain objects, arrays, Date, RegExp, URL, URLSearchParams, Map, Set, Headers, ArrayBuffer, typed arrays, Request, Response, ReadableStream, WritableStream. **Not supported:** Functions, class instances, Symbols, WeakMap/WeakSet. Pass data, not callbacks. ## Streaming Use `getWritable()` to stream data from workflows. `getWritable()` can be called in **both** workflow and step contexts, but you **cannot interact with the stream** (call `getWriter()`, `write()`, `close()`) directly in a workflow function. The stream must be passed to step functions for actual I/O, or steps can call `getWritable()` themselves. **Get the stream in a workflow, pass it to a step:** ```typescript import { getWritable } from "workflow"; export async function myWorkflow() { "use workflow"; const writable = getWritable(); await writeData(writable, "hello world"); } async function writeData(writable: WritableStream, chunk: string) { "use step"; const writer = writable.getWriter(); try { await writer.write(chunk); } finally { writer.releaseLock(); } } ``` **Call `getWritable()` directly inside a step (no need to pass it):** ```typescript import { getWritable } from "workflow"; async function streamData(chunk: string) { "use step"; const writer = getWritable().getWriter(); try { await writer.write(chunk); } finally { writer.releaseLock(); } } ``` ### Namespaced Streams Use `getWritable({ namespace: 'name' })` to create multiple independent streams for different types of data. This is useful for separating logs from primary output, different log levels, agent outputs, metrics, or any distinct data channels. Long-running workflows benefit from namespaced streams because you can replay only the important events (e.g., final results) while keeping verbose logs in a separate stream. **Example: Log levels and agent output separation:** ```typescript import { getWritable } from "workflow"; type LogEntry = { level: "debug" | "info" | "warn" | "error"; message: string; timestamp: number }; type AgentOutput = { type: "thought" | "action" | "result"; content: string }; async function logDebug(message: string) { "use step"; const writer = getWritable({ namespace: "logs:debug" }).getWriter(); try { await writer.write({ level: "debug", message, timestamp: Date.now() }); } finally { writer.releaseLock(); } } async function logInfo(message: string) { "use step"; const writer = getWritable({ namespace: "logs:info" }).getWriter(); try { await writer.write({ level: "info", message, timestamp: Date.now() }); } finally { writer.releaseLock(); } } async function emitAgentThought(thought: string) { "use step"; const writer = getWritable({ namespace: "agent:thoughts" }).getWriter(); try { await writer.write({ type: "thought", content: thought }); } finally { writer.releaseLock(); } } async function emitAgentResult(result: string) { "use step"; // Important results go to the default stream for easy replay const writer = getWritable().getWriter(); try { await writer.write({ type: "result", content: result }); } finally { writer.releaseLock(); } } export async function agentWorkflow(task: string) { "use workflow"; await logInfo(`Starting task: ${task}`); await logDebug("Initializing agent context"); await emitAgentThought("Analyzing the task requirements..."); // ... agent processing ... await emitAgentResult("Task completed successfully"); await logInfo("Workflow finished"); } ``` **Consuming namespaced streams:** ```typescript import { start, getRun } from "workflow/api"; import { agentWorkflow } from "./workflows/agent"; export async function POST(request: Request) { const run = await start(agentWorkflow, ["process data"]); // Access specific streams by namespace const results = run.getReadable({ namespace: undefined }); // Default stream (important results) const infoLogs = run.getReadable({ namespace: "logs:info" }); const debugLogs = run.getReadable({ namespace: "logs:debug" }); const thoughts = run.getReadable({ namespace: "agent:thoughts" }); // Return only important results for most clients return new Response(results, { headers: { "Content-Type": "application/json" } }); } // Resume from a specific point (useful for long sessions) export async function GET(request: Request) { const { searchParams } = new URL(request.url); const runId = searchParams.get("runId")!; const startIndex = parseInt(searchParams.get("startIndex") || "0", 10); const run = getRun(runId); // Resume only the important stream, skip verbose debug logs const stream = run.getReadable({ startIndex }); return new Response(stream); } ``` **Pro tip:** For very long-running sessions (50+ minutes), namespaced streams help manage replay performance. Put verbose/debug output in separate namespaces so you can replay just the important events quickly. ## Debugging ```bash # Check workflow endpoints are reachable npx workflow health npx workflow health --port 3001 # Non-default port # Visual dashboard for runs npx workflow web npx workflow web # CLI inspection (use --json for machine-readable output, --help for full usage) npx workflow inspect runs npx workflow inspect run # For Vercel-deployed projects, specify backend and project npx workflow inspect runs --backend vercel --project --team npx workflow inspect run --backend vercel --project --team # Open Vercel dashboard in browser for a specific run npx workflow inspect run --web npx workflow web --backend vercel --project --team # Cancel a running workflow npx workflow cancel npx workflow cancel --backend vercel --project --team # --env defaults to "production"; use --env preview for preview deployments ``` **Debugging tips:** - Use `--json` (`-j`) on any command for machine-readable output - Use `--web` to open the Vercel Observability dashboard in your browser - Use `--help` on any command for full usage details - Only import workflow APIs you actually use. Unused imports can cause 500 errors. ## Testing Workflows Workflow DevKit provides a Vitest plugin for testing workflows in-process — no running server required. **Unit testing steps:** Steps are just functions; without the compiler, `"use step"` is a no-op. Test them directly: ```typescript import { describe, it, expect } from "vitest"; import { createUser } from "./user-signup"; describe("createUser step", () => { it("should create a user", async () => { const user = await createUser("test@example.com"); expect(user.email).toBe("test@example.com"); }); }); ``` **Integration testing:** Use `@workflow/vitest` for workflows using `sleep()`, hooks, webhooks, or retries: ```typescript // vitest.integration.config.ts import { defineConfig } from "vitest/config"; import { workflow } from "@workflow/vitest"; export default defineConfig({ plugins: [workflow()], test: { include: ["**/*.integration.test.ts"], testTimeout: 60_000, }, }); ``` ```typescript // approval.integration.test.ts import { describe, it, expect } from "vitest"; import { start, getRun, resumeHook } from "workflow/api"; import { waitForHook, waitForSleep } from "@workflow/vitest"; import { approvalWorkflow } from "./approval"; describe("approvalWorkflow", () => { it("should publish when approved", async () => { const run = await start(approvalWorkflow, ["doc-123"]); // Wait for the hook, then resume it await waitForHook(run, { token: "approval:doc-123" }); await resumeHook("approval:doc-123", { approved: true, reviewer: "alice" }); // Wait for sleep, then wake it up const sleepId = await waitForSleep(run); await getRun(run.runId).wakeUp({ correlationIds: [sleepId] }); const result = await run.returnValue; expect(result).toEqual({ status: "published", reviewer: "alice" }); }); }); ``` **Testing webhooks:** Use `resumeWebhook()` with a `Request` object — no HTTP server needed: ```typescript import { start, resumeWebhook } from "workflow/api"; import { waitForHook } from "@workflow/vitest"; const run = await start(ingestWorkflow, ["ep-1"]); const hook = await waitForHook(run); // Discovers the random webhook token await resumeWebhook(hook.token, new Request("https://example.com/webhook", { method: "POST", body: JSON.stringify({ event: "order.created" }), })); ``` **Key APIs:** - `start()` — trigger a workflow - `run.returnValue` — await workflow completion - `waitForHook(run, { token? })` / `waitForSleep(run)` — wait for workflow to reach a pause point - `resumeHook(token, data)` / `resumeWebhook(token, request)` — resume paused workflows - `getRun(runId).wakeUp({ correlationIds })` — skip `sleep()` calls **Best practices:** - Keep unit tests (no plugin) and integration tests (`workflow()` plugin) in separate configs - Use deterministic hook tokens based on test data for easier resumption - Set generous `testTimeout` — workflows may run longer than typical unit tests - `vi.mock()` does **not** work in integration tests — step dependencies are bundled by esbuild