refactor: cleanup and add comments for bun plugin

Author: adriandlam

packages/bun/src/builders.ts

@@ -4,6 +4,10 @@ import { join } from 'node:path';
 import { BaseBuilder } from '@workflow/cli/dist/lib/builders/base-builder';
 import type { WorkflowConfig } from '@workflow/cli/dist/lib/config/types';
 
+/**
+ * Workflow builder for Bun.
+ * Creates the workflow, step and webhook bundles
+ */
 export class LocalBuilder extends BaseBuilder {
   #outDir: string;
   constructor(config?: Partial<WorkflowConfig>) {

packages/bun/src/index.ts

@@ -1,36 +1,42 @@
-import type { Serve } from 'bun';
+import { join } from 'node:path';
+import { serve } from 'bun';
 import { LocalBuilder } from './builders';
-import { workflowPlugin } from './plugin';
+import { workflowTransformPlugin } from './plugin';
 
-// Build the workflows
+// Build the workflow bundles/routes
 await new LocalBuilder().build();
 
 // Registers the plugin with Bun runtime
-Bun.plugin(workflowPlugin());
+Bun.plugin(workflowTransformPlugin());
 
-export function createWorkflowRoutes(handlers: {
-  flow: {
-    POST: (
-      req: Request,
-      server: Serve.BaseServeOptions<any>
-    ) => Response | Promise<Response>;
-  };
-  step: {
-    POST: (
-      req: Request,
-      server: Serve.BaseServeOptions<any>
-    ) => Response | Promise<Response>;
+// Register workflow routes
+registerWorkflowRoutes();
+
+/**
+ * Register the generated workflow routes from builder
+ * with a patched Bun.serve
+ */
+async function registerWorkflowRoutes() {
+  const cwd = process.cwd();
+
+  // Workflow routes generated by the builder
+  const defaultRoutes = {
+    '/.well-known/workflow/v1/flow': await import(
+      join(cwd, '.workflows/workflows.js')
+    ),
+    '/.well-known/workflow/v1/step': await import(
+      join(cwd, '.workflows/steps.js')
+    ),
+    '/.well-known/workflow/v1/webhook': await import(
+      join(cwd, '.workflows/webhook.js')
+    ),
   };
-  webhook: any; // Since webhook module exports various things
-}): Serve.Routes<
-  undefined,
-  | '/.well-known/workflow/v1/flow'
-  | '/.well-known/workflow/v1/step'
-  | '/.well-known/workflow/v1/webhook/:token'
-> {
-  return {
-    '/.well-known/workflow/v1/flow': handlers.flow,
-    '/.well-known/workflow/v1/step': handlers.step,
-    '/.well-known/workflow/v1/webhook/:token': handlers.webhook,
+
+  Bun.serve = (config) => {
+    (config.routes as any) = {
+      ...(config.routes as any),
+      ...defaultRoutes,
+    };
+    return serve(config);
   };
 }

packages/bun/src/plugin.ts

@@ -1,10 +1,13 @@
 import { transform } from '@swc/core';
 import type { BunPlugin } from 'bun';
 
-// Plugin to build workflows at runtime and do client mode transform
-export function workflowPlugin(): BunPlugin {
+/**
+ * Bun plugin to transform workflow files with SWC.
+ * Automatically works with Bun HMR.
+ */
+export function workflowTransformPlugin(): BunPlugin {
   return {
-    name: 'workflow-plugin',
+    name: 'workflow-transform-plugin',
     async setup(build) {
       // Client transform plugin - only transform TypeScript files
       build.onLoad({ filter: /\.(ts|tsx)$/ }, async (args) => {

workbench/bun/server.ts

@@ -1,19 +1,12 @@
 import { getHookByToken, getRun, resumeHook, start } from 'workflow/api';
-import { createWorkflowRoutes } from 'workflow/bun';
 import { hydrateWorkflowArguments } from 'workflow/internal/serialization';
-import * as step from './.workflows/steps.js';
-import * as webhook from './.workflows/webhook.js';
-import * as flow from './.workflows/workflows.js';
 import { allWorkflows } from './_workflows.js';
 
 const server = Bun.serve({
   idleTimeout: 30, // Just for local dev e2e tests
   port: 3000,
   // `routes` requires Bun v1.2.3+
   routes: {
-    // Register Workflow DevKit protocol endpoints
-    ...createWorkflowRoutes({ flow, step, webhook }),
-
     // Custom endpoints for triggering workflows and handling webhooks
     '/api/hook': {
       POST: async (req) => {