feat: add PI_WEBFETCH env toggle to disable extension

Author: code-yeongyu

src/index.ts

@@ -8,13 +8,43 @@ interface ResultLike<TDetails> {
 	details?: TDetails;
 }
 
+const ENABLE_ENV = "PI_WEBFETCH";
+
+function parseEnableEnv(envVar: string): boolean {
+	const envValue = process.env[envVar];
+	if (!envValue) {
+		return true;
+	}
+
+	const normalized = envValue.trim().toLowerCase();
+	if (normalized === "0" || normalized === "false" || normalized === "no" || normalized === "off") {
+		return false;
+	}
+
+	if (normalized === "1" || normalized === "true" || normalized === "yes" || normalized === "on") {
+		return true;
+	}
+
+	// Unknown values fall back to default-on behavior.
+	return true;
+}
+
+export function isWebfetchEnabled(): boolean {
+	return parseEnableEnv(ENABLE_ENV);
+}
+
 /**
  * pi-webfetch — URL retrieval for the pi coding agent.
  *
  * Registers one LLM-callable tool:
  *   - webfetch — fetch URL content as markdown, text, or html.
  */
 export default function (pi: ExtensionAPI): void {
+	// When PI_WEBFETCH disables the extension, keep factory callable but skip all registration side effects.
+	if (!isWebfetchEnabled()) {
+		return;
+	}
+
 	pi.registerTool({
 		...webfetch,
 		renderCall: (args, theme) => renderWebfetchCall(args as never, theme),

test/index.test.ts

@@ -0,0 +1,46 @@
+import { describe, expect, it, vi } from "vitest";
+import webfetchExtension, { isWebfetchEnabled } from "../src/index.js";
+
+const ENABLE_ENV = "PI_WEBFETCH";
+
+describe("webfetch extension toggle", () => {
+	it("returns true when PI_WEBFETCH is unset", () => {
+		delete process.env[ENABLE_ENV];
+		expect(isWebfetchEnabled()).toBe(true);
+	});
+
+	it.each(["1", "true", "yes", "on", " TRUE ", "\tYeS\n"])(
+		"returns true for truthy PI_WEBFETCH value %s",
+		(envValue) => {
+			process.env[ENABLE_ENV] = envValue;
+			expect(isWebfetchEnabled()).toBe(true);
+		},
+	);
+
+	it.each(["0", "false", "no", "off", " OFF ", "\nNo\t"])(
+		"returns false for falsy PI_WEBFETCH value %s",
+		(envValue) => {
+			process.env[ENABLE_ENV] = envValue;
+			expect(isWebfetchEnabled()).toBe(false);
+		},
+	);
+
+	it("returns true for unknown PI_WEBFETCH values", () => {
+		process.env[ENABLE_ENV] = "definitely";
+		expect(isWebfetchEnabled()).toBe(true);
+	});
+
+	it("is a no-op when PI_WEBFETCH is disabled", () => {
+		process.env[ENABLE_ENV] = "0";
+		const registerTool = vi.fn();
+		webfetchExtension({ registerTool } as never);
+		expect(registerTool).not.toHaveBeenCalled();
+	});
+
+	it("registers the webfetch tool when PI_WEBFETCH is unset", () => {
+		delete process.env[ENABLE_ENV];
+		const registerTool = vi.fn();
+		webfetchExtension({ registerTool } as never);
+		expect(registerTool).toHaveBeenCalledTimes(1);
+	});
+});