Use today as the compat date instead of relying on the actual workerd compat date

.changeset/deprecate-supportedCompatibilityDate.md

@@ -0,0 +1,7 @@
+---
+"miniflare": minor
+---
+
+Deprecate `supportedCompatibilityDate` export
+
+The `supportedCompatibilityDate` export is now deprecated. Instead of relying on the workerd-derived compatibility date, callers should just use today's date directly, e.g. `new Date().toISOString().slice(0, 10)`.

.changeset/remove-formatCompatibilityDate.md

@@ -0,0 +1,7 @@
+---
+"@cloudflare/workers-utils": minor
+---
+
+Remove `formatCompatibilityDate` from the package's public exports
+
+This utility has been removed from the public API. Callers should use `getTodaysCompatDate()` from `@cloudflare/workers-utils` instead.

.changeset/remove-getLocalWorkerdCompatibilityDate.md

@@ -0,0 +1,7 @@
+---
+"@cloudflare/workers-utils": minor
+---
+
+Remove `getLocalWorkerdCompatibilityDate` from the package
+
+This utility has been removed because its implementation besides being unreliable is no longer needed. Callers should now use today's date as the compatibility date directly, e.g. via `getTodaysCompatDate()` from `@cloudflare/workers-utils`.

.changeset/use-today-date-for-compat.md

@@ -0,0 +1,8 @@
+---
+"create-cloudflare": patch
+"wrangler": patch
+---
+
+Use today's date as the default compatibility date
+
+Previously, when generating a compatibility date for new projects or when no compatibility date was configured, the date was resolved by loading the locally installed `workerd` package via `miniflare`. This approach was unreliable in some package manager environments (notably `pnpm`). The logic now simply uses today's date instead, which is always correct and works reliably across all environments.

.changeset/vite-plugin-compat-date-today.md

@@ -0,0 +1,7 @@
+---
+"@cloudflare/vite-plugin": minor
+---
+
+Update `getLocalWorkerdCompatibilityDate` to return today's date
+
+The re-exported `getLocalWorkerdCompatibilityDate` function from `@cloudflare/vite-plugin` previously resolved the workerd compatibility date by traversing the local `miniflare` installation, which was unreliable in some package manager setups. It now simply returns today's date. The function is also marked as deprecated — callers should just use today's date instead, for example like so: `new Date().toISOString().slice(0, 10)`

.changeset/workers-utils-get-todays-date.md

@@ -0,0 +1,7 @@
+---
+"@cloudflare/workers-utils": minor
+---
+
+Add `getTodaysCompatDate()` utility function
+
+Returns today's date as a `YYYY-MM-DD` string.

packages/create-cloudflare/src/helpers/__tests__/compatDate.test.ts

@@ -1,16 +1,14 @@
-import { getLocalWorkerdCompatibilityDate } from "@cloudflare/workers-utils";
 import {
 	getLatestTypesEntrypoint,
 	getWorkerdCompatibilityDate,
 } from "helpers/compatDate";
-import { afterEach, beforeEach, describe, test, vi } from "vitest";
+import { beforeEach, describe, test, vi } from "vitest";
 import { createTestContext } from "../../__tests__/helpers";
 import { mockSpinner, mockWorkersTypesDirectory } from "./mocks";
 
 vi.mock("helpers/files");
 vi.mock("fs");
 vi.mock("@cloudflare/cli/interactive");
-vi.mock("@cloudflare/workers-utils");
 
 describe("Compatibility Date Helpers", () => {
 	let spinner: ReturnType<typeof mockSpinner>;
@@ -19,41 +17,13 @@ describe("Compatibility Date Helpers", () => {
 		spinner = mockSpinner();
 	});
 
-	afterEach(() => {
-		vi.useRealTimers();
-	});
-
 	describe("getWorkerdCompatibilityDate()", () => {
-		test("normal flow", async ({ expect }) => {
-			vi.mocked(getLocalWorkerdCompatibilityDate).mockReturnValue({
-				date: "2025-01-10",
-				source: "workerd",
-			});
-
-			const date = getWorkerdCompatibilityDate("./my-app");
-
-			const expectedDate = "2025-01-10";
-			expect(date).toBe(expectedDate);
-			expect(spinner.start).toHaveBeenCalled();
-			expect(spinner.stop).toHaveBeenCalledWith(
-				expect.stringContaining(expectedDate)
-			);
-		});
-
-		test("fallback result", async ({ expect }) => {
-			vi.mocked(getLocalWorkerdCompatibilityDate).mockReturnValue({
-				date: "2025-09-27",
-				source: "fallback",
-			});
-
+		test("returns today's date", async ({ expect }) => {
 			const date = getWorkerdCompatibilityDate("./my-app");
 
-			const fallbackDate = "2025-09-27";
-			expect(date).toBe(fallbackDate);
+			expect(date).toMatch(/^\d{4}-\d{2}-\d{2}$/);
 			expect(spinner.start).toHaveBeenCalled();
-			expect(spinner.stop).toHaveBeenCalledWith(
-				expect.stringContaining(fallbackDate)
-			);
+			expect(spinner.stop).toHaveBeenCalledWith(expect.stringContaining(date));
 		});
 	});
 

packages/create-cloudflare/src/helpers/compatDate.ts

@@ -2,29 +2,21 @@ import { readdirSync } from "node:fs";
 import { resolve } from "node:path";
 import { brandColor, dim } from "@cloudflare/cli/colors";
 import { spinner } from "@cloudflare/cli/interactive";
-import { getLocalWorkerdCompatibilityDate } from "@cloudflare/workers-utils";
+import { getTodaysCompatDate } from "@cloudflare/workers-utils";
 import type { C3Context } from "types";
 
 /**
- * Retrieves the latest workerd compatibility date
+ * Retrieves the current date as a workerd compatibility date
  *
- * @returns The latest compatibility date for workerd in the form "YYYY-MM-DD"
+ * @returns Today's date in the form "YYYY-MM-DD"
  */
-export function getWorkerdCompatibilityDate(projectPath: string) {
+export function getWorkerdCompatibilityDate(_projectPath: string) {
 	const s = spinner();
 	s.start("Retrieving current workerd compatibility date");
 
-	const { date, source } = getLocalWorkerdCompatibilityDate({ projectPath });
+	const date = getTodaysCompatDate();
 
-	if (source === "fallback") {
-		s.stop(
-			`${brandColor("compatibility date")} ${dim(
-				` Could not find workerd date, falling back to ${date}`
-			)}`
-		);
-	} else {
-		s.stop(`${brandColor("compatibility date")} ${dim(date)}`);
-	}
+	s.stop(`${brandColor("compatibility date")} ${dim(date)}`);
 	return date;
 }
 

packages/miniflare/src/plugins/core/index.ts

@@ -6,7 +6,7 @@ import { Readable } from "node:stream";
 import tls from "node:tls";
 import { TextEncoder } from "node:util";
 import { DEFAULT_CONTAINER_EGRESS_INTERCEPTOR_IMAGE } from "@cloudflare/containers-shared";
-import { bold } from "kleur/colors";
+import { getTodaysCompatDate } from "@cloudflare/workers-utils";
 import { MockAgent } from "undici";
 import SCRIPT_ENTRY from "worker:core/entry";
 import STRIP_CF_CONNECTING_IP from "worker:core/strip-cf-connecting-ip";
@@ -17,7 +17,6 @@ import {
 	kVoid,
 	Service,
 	ServiceDesignator,
-	supportedCompatibilityDate,
 	Worker_Binding,
 	Worker_ContainerEngine,
 	Worker_DurableObjectNamespace,
@@ -110,7 +109,6 @@ if (process.env.NODE_EXTRA_CA_CERTS !== undefined) {
 }
 
 const encoder = new TextEncoder();
-const numericCompare = new Intl.Collator(undefined, { numeric: true }).compare;
 
 export function createFetchMock() {
 	return new MockAgent();
@@ -473,37 +471,13 @@ function maybeGetCustomServiceService(
 
 const FALLBACK_COMPATIBILITY_DATE = "2000-01-01";
 
-function getCurrentCompatibilityDate() {
-	// Get current compatibility date in UTC timezone
-	const now = new Date().toISOString();
-	return now.substring(0, now.indexOf("T"));
-}
-
-function validateCompatibilityDate(log: Log, compatibilityDate: string) {
-	if (numericCompare(compatibilityDate, getCurrentCompatibilityDate()) > 0) {
+function validateCompatibilityDate(compatibilityDate: string) {
+	if (compatibilityDate > getTodaysCompatDate()) {
 		// If this compatibility date is in the future, throw
 		throw new MiniflareCoreError(
 			"ERR_FUTURE_COMPATIBILITY_DATE",
 			`Compatibility date "${compatibilityDate}" is in the future and unsupported`
 		);
-	} else if (
-		numericCompare(compatibilityDate, supportedCompatibilityDate) > 0
-	) {
-		// If this compatibility date is greater than the maximum supported
-		// compatibility date of the runtime, but not in the future, warn,
-		// and use the maximum supported date instead
-		log.warn(
-			[
-				"The latest compatibility date supported by the installed Cloudflare Workers Runtime is ",
-				bold(`"${supportedCompatibilityDate}"`),
-				",\nbut you've requested ",
-				bold(`"${compatibilityDate}"`),
-				". Falling back to ",
-				bold(`"${supportedCompatibilityDate}"`),
-				"...",
-			].join("")
-		);
-		return supportedCompatibilityDate;
 	}
 	return compatibilityDate;
 }
@@ -773,7 +747,6 @@ export const CORE_PLUGIN: Plugin<
 		}
 
 		const compatibilityDate = validateCompatibilityDate(
-			log,
 			options.compatibilityDate ?? FALLBACK_COMPATIBILITY_DATE
 		);
 

packages/miniflare/src/runtime/index.ts

@@ -290,7 +290,9 @@ export class Runtime {
 							ipcAddress: info.inspectorIpc || "",
 							pid: String(this.#process.pid),
 							scriptName: name,
-							inspectorURL: `ws://127.0.0.1:${ports?.get(kInspectorSocket)}/core:user:${name}`,
+							inspectorURL: `ws://127.0.0.1:${ports?.get(
+								kInspectorSocket
+							)}/core:user:${name}`,
 							waitForDebugger: true,
 							ownId: randomBytes(12).toString("hex"),
 							openerId: info.openerId,
@@ -363,4 +365,7 @@ function getSafeCompatibilityDate(): string {
 	return workerdCompatibilityDate;
 }
 
+/**
+ * @deprecated Use today's date as the compatibility date instead: `new Date().toISOString().slice(0, 10)`
+ */
 export const supportedCompatibilityDate = getSafeCompatibilityDate();

packages/vite-plugin-cloudflare/src/index.ts

@@ -1,3 +1,4 @@
+import { getTodaysCompatDate } from "@cloudflare/workers-utils";
 import { assertWranglerVersion } from "./assert-wrangler-version";
 import { PluginContext } from "./context";
 import { resolvePluginConfig } from "./plugin-config";
@@ -23,9 +24,26 @@ import { wasmHelperPlugin } from "./plugins/wasm";
 import { debuglog } from "./utils";
 import type { SharedContext } from "./context";
 import type { PluginConfig } from "./plugin-config";
+import type { CompatDate } from "@cloudflare/workers-utils";
 import type * as vite from "vite";
 
-export { getLocalWorkerdCompatibilityDate } from "@cloudflare/workers-utils";
+// TODO: simplify this function in the next major release (DEVX-2533)
+/**
+ * @deprecated Use today's date instead (as `YYYY-MM-DD`)
+ *
+ * Gets the compatibility date to use with the local workerd version.
+ *
+ * Note: the function's signature is as is because it needs to be backward compatibly with
+ *       a previous iteration of this, it will be simplified in the next major version of this package.
+ *
+ * @param _options Unused argument (present only for backward compatibility)
+ * @returns Object containing the compatibility date (this is not the date directly for backward compatibility)
+ */
+export function getLocalWorkerdCompatibilityDate(_options?: {
+	projectPath?: string;
+}): { date: CompatDate; source: "workerd" | "fallback" } {
+	return { date: getTodaysCompatDate(), source: "workerd" };
+}
 
 export type { PluginConfig } from "./plugin-config";
 export type { WorkerConfig } from "./workers-configs";

packages/vite-plugin-cloudflare/src/plugin-config.ts

@@ -1,6 +1,6 @@
 import * as path from "node:path";
 import { parseStaticRouting } from "@cloudflare/workers-shared/utils/configuration/parseStaticRouting";
-import { getLocalWorkerdCompatibilityDate } from "@cloudflare/workers-utils";
+import { getTodaysCompatDate } from "@cloudflare/workers-utils";
 import { defu } from "defu";
 import * as vite from "vite";
 import * as wrangler from "wrangler";
@@ -244,11 +244,7 @@ function resolveWorkerConfig(
 					configCustomizer: options.configCustomizer,
 				});
 
-	const { date } = getLocalWorkerdCompatibilityDate({
-		projectPath: options.root,
-	});
-
-	workerConfig.compatibility_date ??= date;
+	workerConfig.compatibility_date ??= getTodaysCompatDate();
 
 	if (isEntryWorker) {
 		workerConfig.name ??= wrangler.unstable_getWorkerNameFromProject(

packages/vitest-pool-workers/src/pool/index.ts

@@ -3,6 +3,7 @@ import crypto from "node:crypto";
 import fs from "node:fs";
 import path from "node:path";
 import { fileURLToPath } from "node:url";
+import { getTodaysCompatDate } from "@cloudflare/workers-utils";
 import * as devalue from "devalue";
 import getPort, { portNumbers } from "get-port";
 import {
@@ -15,7 +16,6 @@ import {
 	Miniflare,
 	structuredSerializableReducers,
 	structuredSerializableRevivers,
-	supportedCompatibilityDate,
 } from "miniflare";
 import semverSatisfies from "semver/functions/satisfies.js";
 import { experimental_readRawConfig } from "wrangler";
@@ -310,14 +310,12 @@ async function buildProjectWorkerOptions(
 	);
 
 	if (runnerWorker.compatibilityDate === undefined) {
-		// No compatibility date was provided, so infer the latest supported date
-		runnerWorker.compatibilityDate ??= supportedCompatibilityDate;
+		// No compatibility date was provided, so use today's date
+		runnerWorker.compatibilityDate = getTodaysCompatDate();
 		log.info(
 			`No compatibility date was provided for project ${getRelativeProjectPath(
 				project
-			)}, defaulting to latest supported date ${
-				runnerWorker.compatibilityDate
-			}.`
+			)}, defaulting to today's date ${runnerWorker.compatibilityDate}.`
 		);
 	}