feat(wrangler): Add type generation support to wrangler dev (#11616)

* Added initial `wrangler dev` type generation support

* Minor `wrangler dev` type generation refactoring

* Add initial `wrangler dev` type generation tests

* Improved dev code generation tests

* Fixed worker utils package validation tests

* Minor `wrangler dev` type generation test fixes

* Fixed unsupported fields validation test fixture

* Added changeset

* Minor type generation property casing fixes

* Improved changelog details

* Fixed `wrangler dev` tests for type generation

* Minor `checkTypesDiff` refactoring

* Minor `wrangler dev` type generation test refactoring

* Fixed `dev.generate_types` default value

* Moved `resolveConfig` comment inside of `checkTypesDiff`

* Updated `wrangler dev --types` doc comment description

* Fixed `wrangler dev --types` "file is up to date" test

Author: NuroDev

.changeset/plain-beds-spend.md

@@ -0,0 +1,26 @@
+---
+"@cloudflare/workers-utils": minor
+"wrangler": minor
+---
+
+Add type generation support to `wrangler dev`
+
+You can now have your worker configuration types be automatically generated when the local Wrangler development server starts.
+
+To use it you can either:
+
+1. Add the `--types` flag when running `wrangler dev`.
+
+2. Update your Wrangler configuration file to add the new `dev.generate_types` boolean property.
+
+```json
+{
+	"$schema": "node_modules/wrangler/config-schema.json",
+	"name": "example",
+	"main": "src/index.ts",
+	"compatibility_date": "2025-12-12",
+	"dev": {
+		"generate_types": true
+	}
+}
+```

packages/workers-utils/src/config/config.ts

@@ -252,6 +252,13 @@ export interface DevConfig {
 	 * Note that windows is only supported via WSL at the moment
 	 */
 	container_engine: ContainerEngine | undefined;
+
+	/**
+	 * Re-generate your worker types when your Wrangler configuration file changes.
+	 *
+	 * @default false
+	 */
+	generate_types: boolean;
 }
 
 export type RawDevConfig = Partial<DevConfig>;
@@ -298,6 +305,7 @@ export const defaultWranglerConfig: Config = {
 		// Note this one is also workers only
 		enable_containers: true,
 		container_engine: undefined,
+		generate_types: false,
 	},
 
 	/** INHERITABLE ENVIRONMENT FIELDS **/

packages/workers-utils/src/config/validation.ts

@@ -113,6 +113,7 @@ export type NormalizeAndValidateConfigArgs = {
 	upstreamProtocol?: string;
 	script?: string;
 	enableContainers?: boolean;
+	generateTypes?: boolean;
 };
 
 const ENGLISH = new Intl.ListFormat("en-US");
@@ -566,6 +567,7 @@ function normalizeAndValidateDev(
 		upstreamProtocol: upstreamProtocolArg,
 		remote: remoteArg,
 		enableContainers: enableContainersArg,
+		generateTypes: generateTypesArg,
 	} = args;
 	assert(
 		localProtocolArg === undefined ||
@@ -582,6 +584,9 @@ function normalizeAndValidateDev(
 		enableContainersArg === undefined ||
 			typeof enableContainersArg === "boolean"
 	);
+	assert(
+		generateTypesArg === undefined || typeof generateTypesArg === "boolean"
+	);
 	const {
 		// On Windows, when specifying `localhost` as the socket hostname, `workerd`
 		// will only listen on the IPv4 loopback `127.0.0.1`, not the IPv6 `::1`:
@@ -601,6 +606,7 @@ function normalizeAndValidateDev(
 		host,
 		enable_containers = enableContainersArg ?? true,
 		container_engine,
+		generate_types = generateTypesArg ?? false,
 		...rest
 	} = rawDev;
 	validateAdditionalProperties(diagnostics, "dev", Object.keys(rest), []);
@@ -647,6 +653,14 @@ function normalizeAndValidateDev(
 		"string"
 	);
 
+	validateOptionalProperty(
+		diagnostics,
+		"dev",
+		"generate_types",
+		generate_types,
+		"boolean"
+	);
+
 	return {
 		ip,
 		port,
@@ -656,6 +670,7 @@ function normalizeAndValidateDev(
 		host,
 		enable_containers,
 		container_engine,
+		generate_types,
 	};
 }
 

packages/workers-utils/tests/config/validation/normalize-and-validate-config.pages.test.ts

@@ -43,6 +43,7 @@ describe("normalizeAndValidateConfig() - Pages configuration", () => {
 						upstream_protocol: "https",
 						host: "127.0.0.0",
 						enable_containers: true,
+						generate_types: false,
 					},
 					send_metrics: true,
 
@@ -145,6 +146,7 @@ describe("normalizeAndValidateConfig() - Pages configuration", () => {
 						upstream_protocol: "https",
 						host: "127.0.0.0",
 						enable_containers: true,
+						generate_types: false,
 					},
 					send_metrics: true,
 
@@ -247,6 +249,7 @@ describe("normalizeAndValidateConfig() - Pages configuration", () => {
 						upstream_protocol: "https",
 						host: "127.0.0.0",
 						enable_containers: true,
+						generate_types: false,
 					},
 					send_metrics: true,
 
@@ -366,6 +369,7 @@ describe("normalizeAndValidateConfig() - Pages configuration", () => {
 						upstream_protocol: "https",
 						host: "127.0.0.0",
 						enable_containers: true,
+						generate_types: false,
 					},
 					send_metrics: true,
 
@@ -476,6 +480,7 @@ describe("normalizeAndValidateConfig() - Pages configuration", () => {
 						upstream_protocol: "https",
 						host: "127.0.0.0",
 						enable_containers: true,
+						generate_types: false,
 					},
 					send_metrics: true,
 
@@ -586,6 +591,7 @@ describe("normalizeAndValidateConfig() - Pages configuration", () => {
 						upstream_protocol: "https",
 						host: "127.0.0.0",
 						enable_containers: true,
+						generate_types: false,
 					},
 					send_metrics: true,
 
@@ -694,6 +700,7 @@ describe("normalizeAndValidateConfig() - Pages configuration", () => {
 						upstream_protocol: "https",
 						host: "127.0.0.0",
 						enable_containers: true,
+						generate_types: false,
 					},
 					send_metrics: true,
 
@@ -842,6 +849,7 @@ function generateRawConfigForPages(
 			local_protocol: "https",
 			upstream_protocol: "https",
 			host: "127.0.0.0",
+			generate_types: false,
 		},
 		send_metrics: true,
 

packages/workers-utils/tests/config/validation/normalize-and-validate-config.test.ts

@@ -44,6 +44,7 @@ describe("normalizeAndValidateConfig()", () => {
 				enable_containers: true,
 				inspector_port: undefined,
 				container_engine: undefined,
+				generate_types: false,
 			},
 			containers: undefined,
 			cloudchamber: {},
@@ -141,6 +142,7 @@ describe("normalizeAndValidateConfig()", () => {
 					local_protocol: "https",
 					upstream_protocol: "http",
 					enable_containers: false,
+					generate_types: false,
 				},
 			};
 
@@ -167,6 +169,7 @@ describe("normalizeAndValidateConfig()", () => {
 					local_protocol: "wss",
 					upstream_protocol: "ws",
 					enable_containers: true,
+					generate_types: false,
 				},
 			};
 

packages/wrangler/src/__tests__/config-validation-pages.test.ts

@@ -186,6 +186,7 @@ describe("validatePagesConfig()", () => {
 						host: "test-host",
 						enable_containers: false,
 						container_engine: undefined,
+						generate_types: false,
 					},
 				},
 			};