[Lit] render DSD attributes based on shadowRootOptions (#6351)

* [Lit] render DSD attributes based on `shadowRootOptions`

## Changes

- Update `@astrojs/lit`’s `server.js` to properly render elements with `delegatesFocus: false` set in their `shadowRootOptions`.
- Logic is based on `@lit-labs/ssr` [latest implementation as found here](b0c3f82ef0/packages/labs/ssr/src/lib/render-value.ts (L738))

## Testing

A test was added to ensure an element with `delegatesFocus` set to true has this attribute properly included in the rendered static markup.

* chore: add changeset

.changeset/old-fireants-allow.md

@@ -0,0 +1,5 @@
+---
+'@astrojs/lit': patch
+---
+
+Render DSD attributes based on `shadowRootOptions`

packages/integrations/lit/server.js

@@ -62,7 +62,11 @@ function* render(Component, attrs, slots) {
 	yield `>`;
 	const shadowContents = instance.renderShadow({});
 	if (shadowContents !== undefined) {
-		yield '<template shadowroot="open" shadowrootmode="open">';
+		const { mode = 'open', delegatesFocus } = instance.shadowRootOptions ?? {};
+    // `delegatesFocus` is intentionally allowed to coerce to boolean to
+    // match web platform behavior.
+    const delegatesfocusAttr = delegatesFocus ? ' shadowrootdelegatesfocus' : '';
+		yield `<template shadowroot="${mode}" shadowrootmode="${mode}"${delegatesfocusAttr}>`;
 		yield* shadowContents;
 		yield '</template>';
 	}

packages/integrations/lit/test/server.test.js

@@ -83,4 +83,15 @@ describe('renderToStaticMarkup', () => {
 		expect($(tagName).attr('attr1')).to.equal(attr1);
 		expect($(`${tagName} template`).text()).to.contain(`Hello ${prop1}`);
 	});
+
+	it('should render DSD attributes based on shadowRootOptions', async () => {
+		const tagName = 'lit-component';
+		customElements.define(tagName, class extends LitElement {
+			static shadowRootOptions = {...LitElement.shadowRootOptions, delegatesFocus: true};
+		});
+		const render = await renderToStaticMarkup(tagName);
+		expect(render).to.deep.equal({
+			html: `<${tagName}><template shadowroot=\"open\" shadowrootmode=\"open\" shadowrootdelegatesfocus><!--lit-part--><!--/lit-part--></template></${tagName}>`,
+		});
+	});
 });