Fix DevTools port conflict during type generation

Prevents EADDRINUSE error when running typegen and dev server simultaneously
by detecting type generation context and disabling DevTools.

- Add isTypegenContext() to detect typegen via env vars and argv
- Return empty plugin array when in typegen context
- Add comprehensive unit tests (18 tests total)
- Maintain backward compatibility for normal dev mode

Fixes port 42069 conflict with TanStack DevTools during typegen execution.

Author: FAL-coffee

packages/react-router-devtools/src/vite/plugin.test.ts

@@ -0,0 +1,77 @@
+import { beforeEach, describe, expect, it, vi } from "vitest"
+import { reactRouterDevTools } from "./plugin"
+
+// Mock the detect-typegen module
+vi.mock("./utils/detect-typegen", () => ({
+	isTypegenContext: vi.fn(),
+}))
+
+describe("reactRouterDevTools", () => {
+	let isTypegenContext: ReturnType<typeof vi.fn>
+
+	beforeEach(async () => {
+		vi.clearAllMocks()
+		const module = await import("./utils/detect-typegen")
+		isTypegenContext = vi.mocked(module.isTypegenContext)
+	})
+
+	describe("typegen context", () => {
+		it("should return empty array when in typegen context", () => {
+			isTypegenContext.mockReturnValue(true)
+
+			const plugins = reactRouterDevTools()
+
+			expect(plugins).toEqual([])
+			expect(isTypegenContext).toHaveBeenCalledTimes(1)
+		})
+
+		it("should return empty array even with config options in typegen context", () => {
+			isTypegenContext.mockReturnValue(true)
+
+			const plugins = reactRouterDevTools({
+				client: { expansionLevel: 2 },
+			})
+
+			expect(plugins).toEqual([])
+			expect(isTypegenContext).toHaveBeenCalledTimes(1)
+		})
+	})
+
+	describe("normal context", () => {
+		it("should return plugin array in normal context", () => {
+			isTypegenContext.mockReturnValue(false)
+
+			const plugins = reactRouterDevTools()
+
+			expect(Array.isArray(plugins)).toBe(true)
+			expect(plugins.length).toBeGreaterThan(0)
+			expect(isTypegenContext).toHaveBeenCalledTimes(1)
+		})
+
+		it("should return multiple plugins including TanStack DevTools", () => {
+			isTypegenContext.mockReturnValue(false)
+
+			const plugins = reactRouterDevTools()
+
+			// TanStack DevTools returns an array that gets spread
+			// + 5 custom plugins = 6+ total
+			expect(plugins.length).toBeGreaterThan(5)
+
+			// Verify plugin names exist
+			const pluginNames = plugins.filter((p) => p.name).map((p) => p.name)
+
+			expect(pluginNames).toContain("react-router-devtools")
+		})
+
+		it("should return plugin array when config options are provided", () => {
+			isTypegenContext.mockReturnValue(false)
+
+			const plugins = reactRouterDevTools({
+				server: { silent: false },
+			})
+
+			expect(Array.isArray(plugins)).toBe(true)
+			expect(plugins.length).toBeGreaterThan(5)
+		})
+	})
+})

packages/react-router-devtools/src/vite/plugin.tsx

@@ -11,6 +11,7 @@ import { augmentDataFetchingFunctions } from "./utils/data-functions-augment.js"
 import { injectRdtClient } from "./utils/inject-client.js"
 import { injectContext } from "./utils/inject-context.js"
 import { augmentMiddlewareFunctions } from "./utils/middleware-augment.js"
+import { isTypegenContext } from "./utils/detect-typegen.js"
 // this should mirror the types in server/config.ts as well as they are bundled separately.
 declare global {
 	interface Window {
@@ -170,6 +171,11 @@ type Route = {
 export const defineRdtConfig = (config: ReactRouterViteConfig) => config
 
 export const reactRouterDevTools: (args?: ReactRouterViteConfig) => Plugin[] = (args) => {
+	// Return empty array in typegen context (disable DevTools)
+	if (isTypegenContext()) {
+		return []
+	}
+
 	const serverConfig = args?.server || {}
 	const clientConfig = {
 		...args?.client,

packages/react-router-devtools/src/vite/utils/detect-typegen.test.ts

@@ -0,0 +1,91 @@
+import { afterEach, beforeEach, describe, expect, it } from "vitest"
+import { isTypegenContext } from "./detect-typegen"
+
+describe("isTypegenContext", () => {
+	const originalEnv = process.env
+	const originalArgv = process.argv
+
+	beforeEach(() => {
+		// Reset environment to clean state
+		process.env = { ...originalEnv }
+		process.argv = [...originalArgv]
+	})
+
+	afterEach(() => {
+		// Restore environment after test
+		process.env = originalEnv
+		process.argv = originalArgv
+	})
+
+	describe("environment variable detection", () => {
+		it("should return true when TYPEGEN_RUNNING=1", () => {
+			process.env.TYPEGEN_RUNNING = "1"
+			expect(isTypegenContext()).toBe(true)
+		})
+
+		it("should return true when SAFE_ROUTES_TYPEGEN=1", () => {
+			process.env.SAFE_ROUTES_TYPEGEN = "1"
+			expect(isTypegenContext()).toBe(true)
+		})
+
+		it("should return true when npm_lifecycle_event contains typegen (pre)", () => {
+			// cspell:disable-next-line
+			process.env.npm_lifecycle_event = "pretypegen"
+			expect(isTypegenContext()).toBe(true)
+		})
+
+		it("should return true when npm_lifecycle_event contains typegen (post)", () => {
+			// cspell:disable-next-line
+			process.env.npm_lifecycle_event = "posttypegen"
+			expect(isTypegenContext()).toBe(true)
+		})
+	})
+
+	describe("command line argument detection", () => {
+		it("should return true when process.argv contains typegen", () => {
+			process.argv = ["node", "script.js", "typegen"]
+			expect(isTypegenContext()).toBe(true)
+		})
+
+		it("should return true when process.argv contains type-gen", () => {
+			process.argv = ["node", "script.js", "type-gen"]
+			expect(isTypegenContext()).toBe(true)
+		})
+
+		it("should return true when process.argv contains react-router typegen", () => {
+			process.argv = ["node", "script.js", "react-router", "typegen"]
+			expect(isTypegenContext()).toBe(true)
+		})
+
+		it("should return true when process.argv contains safe-routes", () => {
+			process.argv = ["node", "script.js", "safe-routes"]
+			expect(isTypegenContext()).toBe(true)
+		})
+	})
+
+	describe("normal context", () => {
+		it("should return false when no typegen indicators are present", () => {
+			expect(isTypegenContext()).toBe(false)
+		})
+
+		it("should return false with unrelated environment variables", () => {
+			process.env.OTHER_VAR = "1"
+			expect(isTypegenContext()).toBe(false)
+		})
+
+		it("should return false with unrelated command line arguments", () => {
+			process.argv = ["node", "script.js", "dev", "build"]
+			expect(isTypegenContext()).toBe(false)
+		})
+
+		it("should return false when TYPEGEN_RUNNING=0", () => {
+			process.env.TYPEGEN_RUNNING = "0"
+			expect(isTypegenContext()).toBe(false)
+		})
+
+		it("should return false when TYPEGEN_RUNNING is empty string", () => {
+			process.env.TYPEGEN_RUNNING = ""
+			expect(isTypegenContext()).toBe(false)
+		})
+	})
+})

packages/react-router-devtools/src/vite/utils/detect-typegen.ts

@@ -0,0 +1,37 @@
+/**
+ * Detects if running in a typegen context
+ *
+ * Returns true if any of the following conditions are met:
+ * - Environment variables: TYPEGEN_RUNNING=1, SAFE_ROUTES_TYPEGEN=1
+ * - npm script: npm_lifecycle_event contains "typegen"
+ * - Command line arguments: contains "typegen", "type-gen", "react-router typegen", or "safe-routes"
+ *
+ * @returns true if in typegen context, false otherwise
+ */
+export function isTypegenContext(): boolean {
+	// Check environment variables
+	if (
+		process.env.TYPEGEN_RUNNING === "1" ||
+		process.env.SAFE_ROUTES_TYPEGEN === "1"
+	) {
+		return true
+	}
+
+	// Check npm lifecycle event
+	if (process.env.npm_lifecycle_event?.includes("typegen")) {
+		return true
+	}
+
+	// Check command line arguments
+	const args = process.argv.join(" ")
+	if (
+		args.includes("typegen") ||
+		args.includes("type-gen") ||
+		args.includes("react-router typegen") ||
+		args.includes("safe-routes")
+	) {
+		return true
+	}
+
+	return false
+}