From 84032dee4b5473fb06bcc17ddeaeb945d1a82b0d Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Mon, 11 Apr 2022 12:32:57 -0400
Subject: [PATCH 01/13] start working on v3 filesystem API

---
 packages/adapter-vercel/index.js | 55 +++++++++++++++++++-------------
 1 file changed, 33 insertions(+), 22 deletions(-)

diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index 7ed513d8eb9e..6d4b0b59c678 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -3,7 +3,7 @@ import { posix } from 'path';
 import { fileURLToPath } from 'url';
 import esbuild from 'esbuild';
 
-const dir = '.vercel_build_output';
+const dir = '.vercel/output';
 
 // rules for clean URLs and trailing slash handling,
 // generated with @vercel/routing-utils
@@ -97,7 +97,7 @@ export default function ({ external = [] } = {}) {
 
 			const dirs = {
 				static: `${dir}/static`,
-				lambda: `${dir}/functions/node/render`
+				lambda: `${dir}/functions/render.func`
 			};
 
 			builder.log.minor('Generating serverless function...');
@@ -124,9 +124,18 @@ export default function ({ external = [] } = {}) {
 				target: 'node14',
 				bundle: true,
 				platform: 'node',
+				format: 'esm',
 				external
 			});
 
+			writeFileSync(
+				`${dirs.lambda}/.vc-config.json`,
+				JSON.stringify({
+					runtime: 'nodejs14.x',
+					handler: 'handle'
+				})
+			);
+
 			writeFileSync(`${dirs.lambda}/package.json`, JSON.stringify({ type: 'commonjs' }));
 
 			builder.log.minor('Copying assets...');
@@ -137,8 +146,6 @@ export default function ({ external = [] } = {}) {
 
 			builder.log.minor('Writing routes...');
 
-			builder.mkdirp(`${dir}/config`);
-
 			const prerendered_pages = Array.from(builder.prerendered.pages, ([src, page]) => ({
 				src,
 				dest: page.file
@@ -156,25 +163,29 @@ export default function ({ external = [] } = {}) {
 			);
 
 			writeFileSync(
-				`${dir}/config/routes.json`,
-				JSON.stringify([
-					...redirects[builder.config.kit.trailingSlash],
-					...prerendered_pages,
-					...prerendered_redirects,
-					{
-						src: `/${builder.config.kit.appDir}/.+`,
-						headers: {
-							'cache-control': 'public, immutable, max-age=31536000'
+				`${dir}/config.json`,
+				JSON.stringify({
+					version: 3,
+					target: 'production',
+					routes: [
+						...redirects[builder.config.kit.trailingSlash],
+						...prerendered_pages,
+						...prerendered_redirects,
+						{
+							src: `/${builder.config.kit.appDir}/.+`,
+							headers: {
+								'cache-control': 'public, immutable, max-age=31536000'
+							}
+						},
+						{
+							handle: 'filesystem'
+						},
+						{
+							src: '/.*',
+							dest: 'render'
 						}
-					},
-					{
-						handle: 'filesystem'
-					},
-					{
-						src: '/.*',
-						dest: '.vercel/functions/render'
-					}
-				])
+					]
+				})
 			);
 		}
 	};

From f5a0b181f1eded1e63cc37bfa036f36487622c6d Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Tue, 19 Apr 2022 14:18:10 -0400
Subject: [PATCH 02/13] fix

---
 packages/adapter-vercel/index.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index 6d4b0b59c678..2a40519296c7 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -124,7 +124,7 @@ export default function ({ external = [] } = {}) {
 				target: 'node14',
 				bundle: true,
 				platform: 'node',
-				format: 'esm',
+				format: 'cjs',
 				external
 			});
 
@@ -132,7 +132,8 @@ export default function ({ external = [] } = {}) {
 				`${dirs.lambda}/.vc-config.json`,
 				JSON.stringify({
 					runtime: 'nodejs14.x',
-					handler: 'handle'
+					handler: 'index.js',
+					launcherType: 'Nodejs'
 				})
 			);
 

From 12f0c854fa0003ad6074ba21b85aef4f64302664 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Tue, 19 Apr 2022 14:25:05 -0400
Subject: [PATCH 03/13] support v1 and v3

---
 packages/adapter-vercel/index.js | 295 +++++++++++++++++++++----------
 1 file changed, 199 insertions(+), 96 deletions(-)

diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index 2a40519296c7..8c6eae5a458c 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -3,8 +3,6 @@ import { posix } from 'path';
 import { fileURLToPath } from 'url';
 import esbuild from 'esbuild';
 
-const dir = '.vercel/output';
-
 // rules for clean URLs and trailing slash handling,
 // generated with @vercel/routing-utils
 const redirects = {
@@ -88,106 +86,211 @@ export default function ({ external = [] } = {}) {
 		name: '@sveltejs/adapter-vercel',
 
 		async adapt(builder) {
-			const tmp = builder.getBuildDirectory('vercel-tmp');
+			if (process.env.ENABLE_VC_BUILD) {
+				await v3(builder, external);
+			} else {
+				await v1(builder, external);
+			}
+		}
+	};
+}
 
-			builder.rimraf(dir);
-			builder.rimraf(tmp);
+/**
+ * @param {import('@sveltejs/kit').Builder} builder
+ * @param {string[]} external
+ */
+async function v1(builder, external) {
+	const dir = '.vercel_build_output';
 
-			const files = fileURLToPath(new URL('./files', import.meta.url).href);
+	const tmp = builder.getBuildDirectory('vercel-tmp');
 
-			const dirs = {
-				static: `${dir}/static`,
-				lambda: `${dir}/functions/render.func`
-			};
+	builder.rimraf(dir);
+	builder.rimraf(tmp);
 
-			builder.log.minor('Generating serverless function...');
+	const files = fileURLToPath(new URL('./files', import.meta.url).href);
 
-			const relativePath = posix.relative(tmp, builder.getServerDirectory());
+	const dirs = {
+		static: `${dir}/static`,
+		lambda: `${dir}/functions/node/render`
+	};
 
-			builder.copy(files, tmp, {
-				replace: {
-					SERVER: `${relativePath}/index.js`,
-					MANIFEST: './manifest.js'
-				}
-			});
-
-			writeFileSync(
-				`${tmp}/manifest.js`,
-				`export const manifest = ${builder.generateManifest({
-					relativePath
-				})};\n`
-			);
-
-			await esbuild.build({
-				entryPoints: [`${tmp}/entry.js`],
-				outfile: `${dirs.lambda}/index.js`,
-				target: 'node14',
-				bundle: true,
-				platform: 'node',
-				format: 'cjs',
-				external
-			});
-
-			writeFileSync(
-				`${dirs.lambda}/.vc-config.json`,
-				JSON.stringify({
-					runtime: 'nodejs14.x',
-					handler: 'index.js',
-					launcherType: 'Nodejs'
-				})
-			);
-
-			writeFileSync(`${dirs.lambda}/package.json`, JSON.stringify({ type: 'commonjs' }));
-
-			builder.log.minor('Copying assets...');
-
-			builder.writeStatic(dirs.static);
-			builder.writeClient(dirs.static);
-			builder.writePrerendered(dirs.static);
-
-			builder.log.minor('Writing routes...');
-
-			const prerendered_pages = Array.from(builder.prerendered.pages, ([src, page]) => ({
-				src,
-				dest: page.file
-			}));
-
-			const prerendered_redirects = Array.from(
-				builder.prerendered.redirects,
-				([src, redirect]) => ({
-					src,
-					headers: {
-						Location: redirect.location
-					},
-					status: redirect.status
-				})
-			);
-
-			writeFileSync(
-				`${dir}/config.json`,
-				JSON.stringify({
-					version: 3,
-					target: 'production',
-					routes: [
-						...redirects[builder.config.kit.trailingSlash],
-						...prerendered_pages,
-						...prerendered_redirects,
-						{
-							src: `/${builder.config.kit.appDir}/.+`,
-							headers: {
-								'cache-control': 'public, immutable, max-age=31536000'
-							}
-						},
-						{
-							handle: 'filesystem'
-						},
-						{
-							src: '/.*',
-							dest: 'render'
-						}
-					]
-				})
-			);
+	builder.log.minor('Generating serverless function...');
+
+	const relativePath = posix.relative(tmp, builder.getServerDirectory());
+
+	builder.copy(files, tmp, {
+		replace: {
+			SERVER: `${relativePath}/index.js`,
+			MANIFEST: './manifest.js'
 		}
+	});
+
+	writeFileSync(
+		`${tmp}/manifest.js`,
+		`export const manifest = ${builder.generateManifest({
+			relativePath
+		})};\n`
+	);
+
+	await esbuild.build({
+		entryPoints: [`${tmp}/entry.js`],
+		outfile: `${dirs.lambda}/index.js`,
+		target: 'node14',
+		bundle: true,
+		platform: 'node',
+		external
+	});
+
+	writeFileSync(`${dirs.lambda}/package.json`, JSON.stringify({ type: 'commonjs' }));
+
+	builder.log.minor('Copying assets...');
+
+	builder.writeStatic(dirs.static);
+	builder.writeClient(dirs.static);
+	builder.writePrerendered(dirs.static);
+
+	builder.log.minor('Writing routes...');
+
+	builder.mkdirp(`${dir}/config`);
+
+	const prerendered_pages = Array.from(builder.prerendered.pages, ([src, page]) => ({
+		src,
+		dest: page.file
+	}));
+
+	const prerendered_redirects = Array.from(builder.prerendered.redirects, ([src, redirect]) => ({
+		src,
+		headers: {
+			Location: redirect.location
+		},
+		status: redirect.status
+	}));
+
+	writeFileSync(
+		`${dir}/config/routes.json`,
+		JSON.stringify([
+			...redirects[builder.config.kit.trailingSlash],
+			...prerendered_pages,
+			...prerendered_redirects,
+			{
+				src: `/${builder.config.kit.appDir}/.+`,
+				headers: {
+					'cache-control': 'public, immutable, max-age=31536000'
+				}
+			},
+			{
+				handle: 'filesystem'
+			},
+			{
+				src: '/.*',
+				dest: '.vercel/functions/render'
+			}
+		])
+	);
+}
+
+/**
+ * @param {import('@sveltejs/kit').Builder} builder
+ * @param {string[]} external
+ */
+async function v3(builder, external) {
+	const dir = '.vercel/output';
+
+	const tmp = builder.getBuildDirectory('vercel-tmp');
+
+	builder.rimraf(dir);
+	builder.rimraf(tmp);
+
+	const files = fileURLToPath(new URL('./files', import.meta.url).href);
+
+	const dirs = {
+		static: `${dir}/static`,
+		lambda: `${dir}/functions/render.func`
 	};
+
+	builder.log.minor('Generating serverless function...');
+
+	const relativePath = posix.relative(tmp, builder.getServerDirectory());
+
+	builder.copy(files, tmp, {
+		replace: {
+			SERVER: `${relativePath}/index.js`,
+			MANIFEST: './manifest.js'
+		}
+	});
+
+	writeFileSync(
+		`${tmp}/manifest.js`,
+		`export const manifest = ${builder.generateManifest({
+			relativePath
+		})};\n`
+	);
+
+	await esbuild.build({
+		entryPoints: [`${tmp}/entry.js`],
+		outfile: `${dirs.lambda}/index.js`,
+		target: 'node14',
+		bundle: true,
+		platform: 'node',
+		format: 'cjs',
+		external
+	});
+
+	writeFileSync(
+		`${dirs.lambda}/.vc-config.json`,
+		JSON.stringify({
+			runtime: 'nodejs14.x',
+			handler: 'index.js',
+			launcherType: 'Nodejs'
+		})
+	);
+
+	writeFileSync(`${dirs.lambda}/package.json`, JSON.stringify({ type: 'commonjs' }));
+
+	builder.log.minor('Copying assets...');
+
+	builder.writeStatic(dirs.static);
+	builder.writeClient(dirs.static);
+	builder.writePrerendered(dirs.static);
+
+	builder.log.minor('Writing routes...');
+
+	const prerendered_pages = Array.from(builder.prerendered.pages, ([src, page]) => ({
+		src,
+		dest: page.file
+	}));
+
+	const prerendered_redirects = Array.from(builder.prerendered.redirects, ([src, redirect]) => ({
+		src,
+		headers: {
+			Location: redirect.location
+		},
+		status: redirect.status
+	}));
+
+	writeFileSync(
+		`${dir}/config.json`,
+		JSON.stringify({
+			version: 3,
+			target: 'production',
+			routes: [
+				...redirects[builder.config.kit.trailingSlash],
+				...prerendered_pages,
+				...prerendered_redirects,
+				{
+					src: `/${builder.config.kit.appDir}/.+`,
+					headers: {
+						'cache-control': 'public, immutable, max-age=31536000'
+					}
+				},
+				{
+					handle: 'filesystem'
+				},
+				{
+					src: '/.*',
+					dest: 'render'
+				}
+			]
+		})
+	);
 }

From 18661ce6c5cbcc480c6a3026e1911857462aa3be Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Tue, 19 Apr 2022 15:37:11 -0400
Subject: [PATCH 04/13] implement route splitting

---
 packages/adapter-vercel/index.d.ts     |   2 +
 packages/adapter-vercel/index.js       | 177 +++++++++++++++++--------
 packages/kit/src/core/adapt/builder.js |   5 +-
 packages/kit/types/index.d.ts          |   2 +-
 packages/kit/types/private.d.ts        |   3 +-
 5 files changed, 132 insertions(+), 57 deletions(-)

diff --git a/packages/adapter-vercel/index.d.ts b/packages/adapter-vercel/index.d.ts
index 25e220d37ec8..1566ac142b82 100644
--- a/packages/adapter-vercel/index.d.ts
+++ b/packages/adapter-vercel/index.d.ts
@@ -1,7 +1,9 @@
 import { Adapter } from '@sveltejs/kit';
 
 type Options = {
+	edge?: boolean;
 	external?: string[];
+	split?: boolean;
 };
 
 declare function plugin(options?: Options): Adapter;
diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index 8c6eae5a458c..50ad217a2a1b 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -1,5 +1,5 @@
-import { writeFileSync } from 'fs';
-import { posix } from 'path';
+import { fstat, mkdirSync, writeFileSync } from 'fs';
+import { dirname, posix } from 'path';
 import { fileURLToPath } from 'url';
 import esbuild from 'esbuild';
 
@@ -81,14 +81,18 @@ const redirects = {
 };
 
 /** @type {import('.')} **/
-export default function ({ external = [] } = {}) {
+export default function ({ external = [], edge, split } = {}) {
 	return {
 		name: '@sveltejs/adapter-vercel',
 
 		async adapt(builder) {
 			if (process.env.ENABLE_VC_BUILD) {
-				await v3(builder, external);
+				await v3(builder, external, edge, split);
 			} else {
+				if (edge || split) {
+					throw new Error('edge and split options can only be used with ENABLE_VC_BUILD');
+				}
+
 				await v1(builder, external);
 			}
 		}
@@ -192,8 +196,10 @@ async function v1(builder, external) {
 /**
  * @param {import('@sveltejs/kit').Builder} builder
  * @param {string[]} external
+ * @param {boolean} edge
+ * @param {boolean} split
  */
-async function v3(builder, external) {
+async function v3(builder, external, edge, split) {
 	const dir = '.vercel/output';
 
 	const tmp = builder.getBuildDirectory('vercel-tmp');
@@ -205,47 +211,111 @@ async function v3(builder, external) {
 
 	const dirs = {
 		static: `${dir}/static`,
-		lambda: `${dir}/functions/render.func`
+		functions: `${dir}/functions`
 	};
 
-	builder.log.minor('Generating serverless function...');
+	// TODO use `overrides` rather than `routes`
+	const prerendered_pages = Array.from(builder.prerendered.pages, ([src, page]) => ({
+		src,
+		dest: page.file
+	}));
 
-	const relativePath = posix.relative(tmp, builder.getServerDirectory());
+	const prerendered_redirects = Array.from(builder.prerendered.redirects, ([src, redirect]) => ({
+		src,
+		headers: {
+			Location: redirect.location
+		},
+		status: redirect.status
+	}));
 
-	builder.copy(files, tmp, {
-		replace: {
-			SERVER: `${relativePath}/index.js`,
-			MANIFEST: './manifest.js'
+	const routes = [
+		...redirects[builder.config.kit.trailingSlash],
+		...prerendered_pages,
+		...prerendered_redirects,
+		{
+			src: `/${builder.config.kit.appDir}/.+`,
+			headers: {
+				'cache-control': 'public, immutable, max-age=31536000'
+			}
+		},
+		{
+			handle: 'filesystem'
+		},
+		{
+			src: '/.*',
+			dest: 'render'
 		}
-	});
+	];
 
-	writeFileSync(
-		`${tmp}/manifest.js`,
-		`export const manifest = ${builder.generateManifest({
-			relativePath
-		})};\n`
-	);
-
-	await esbuild.build({
-		entryPoints: [`${tmp}/entry.js`],
-		outfile: `${dirs.lambda}/index.js`,
-		target: 'node14',
-		bundle: true,
-		platform: 'node',
-		format: 'cjs',
-		external
-	});
-
-	writeFileSync(
-		`${dirs.lambda}/.vc-config.json`,
-		JSON.stringify({
-			runtime: 'nodejs14.x',
-			handler: 'index.js',
-			launcherType: 'Nodejs'
-		})
-	);
+	builder.log.minor('Generating serverless function...');
 
-	writeFileSync(`${dirs.lambda}/package.json`, JSON.stringify({ type: 'commonjs' }));
+	/**
+	 * @param {string} name
+	 * @param {string} pattern
+	 * @param {(options: { relativePath: string }) => string} generate_manifest
+	 */
+	async function generate_serverless_function(name, pattern, generate_manifest) {
+		const tmp = builder.getBuildDirectory(`vercel-tmp/${name}`);
+		const relativePath = posix.relative(tmp, builder.getServerDirectory());
+
+		builder.copy(files, tmp, {
+			replace: {
+				SERVER: `${relativePath}/index.js`,
+				MANIFEST: './manifest.js'
+			}
+		});
+
+		write(
+			`${tmp}/manifest.js`,
+			`export const manifest = ${generate_manifest({ relativePath })};\n`
+		);
+
+		await esbuild.build({
+			entryPoints: [`${tmp}/entry.js`],
+			outfile: `${dirs.functions}/${name}.func/index.js`,
+			target: 'node14',
+			bundle: true,
+			platform: 'node',
+			format: 'cjs',
+			external
+		});
+
+		write(
+			`${dirs.functions}/${name}.func/.vc-config.json`,
+			JSON.stringify({
+				runtime: 'nodejs14.x',
+				handler: 'index.js',
+				launcherType: 'Nodejs'
+			})
+		);
+
+		write(`${dirs.functions}/${name}.func/package.json`, JSON.stringify({ type: 'commonjs' }));
+
+		routes.push({ src: pattern, dest: name });
+	}
+
+	/**
+	 * @param {string} name
+	 * @param {string} pattern
+	 */
+	async function generate_edge_function(name, pattern) {}
+
+	const generate_function = edge ? generate_edge_function : generate_serverless_function;
+
+	if (split) {
+		await builder.createEntries((route) => {
+			return {
+				id: route.pattern.toString(), // TODO is `id` necessary?
+				filter: (other) => route.pattern.toString() === other.pattern.toString(),
+				complete: async (entry) => {
+					const src = `/${route.pattern}`;
+					await generate_function(route.id, src, entry.generateManifest);
+				}
+			};
+		});
+	} else {
+		generate_function('render', '/.*', builder.generateManifest);
+	}
 
 	builder.log.minor('Copying assets...');
 
@@ -255,20 +325,7 @@ async function v3(builder, external) {
 
 	builder.log.minor('Writing routes...');
 
-	const prerendered_pages = Array.from(builder.prerendered.pages, ([src, page]) => ({
-		src,
-		dest: page.file
-	}));
-
-	const prerendered_redirects = Array.from(builder.prerendered.redirects, ([src, redirect]) => ({
-		src,
-		headers: {
-			Location: redirect.location
-		},
-		status: redirect.status
-	}));
-
-	writeFileSync(
+	write(
 		`${dir}/config.json`,
 		JSON.stringify({
 			version: 3,
@@ -294,3 +351,17 @@ async function v3(builder, external) {
 		})
 	);
 }
+
+/**
+ * @param {string} file
+ * @param {string} data
+ */
+function write(file, data) {
+	try {
+		mkdirSync(dirname(file), { recursive: true });
+	} catch {
+		// do nothing
+	}
+
+	writeFileSync(file, data);
+}
diff --git a/packages/kit/src/core/adapt/builder.js b/packages/kit/src/core/adapt/builder.js
index 7c589dff643a..057d06dd80f2 100644
--- a/packages/kit/src/core/adapt/builder.js
+++ b/packages/kit/src/core/adapt/builder.js
@@ -33,11 +33,12 @@ export function create_builder({ config, build_data, prerendered, log }) {
 		config,
 		prerendered,
 
-		createEntries(fn) {
+		async createEntries(fn) {
 			const { routes } = build_data.manifest_data;
 
 			/** @type {import('types').RouteDefinition[]} */
 			const facades = routes.map((route) => ({
+				id: route.id,
 				type: route.type,
 				segments: route.id.split('/').map((segment) => ({
 					dynamic: segment.includes('['),
@@ -81,7 +82,7 @@ export function create_builder({ config, build_data, prerendered, log }) {
 				});
 
 				if (filtered.size > 0) {
-					complete({
+					await complete({
 						generateManifest: ({ relativePath, format }) =>
 							generate_manifest({
 								build_data,
diff --git a/packages/kit/types/index.d.ts b/packages/kit/types/index.d.ts
index 088596ed4354..5a13705ef5f2 100644
--- a/packages/kit/types/index.d.ts
+++ b/packages/kit/types/index.d.ts
@@ -41,7 +41,7 @@ export interface Builder {
 	 * Create entry points that map to individual functions
 	 * @param fn A function that groups a set of routes into an entry point
 	 */
-	createEntries(fn: (route: RouteDefinition) => AdapterEntry): void;
+	createEntries(fn: (route: RouteDefinition) => AdapterEntry): Promise<void>;
 
 	generateManifest: (opts: { relativePath: string; format?: 'esm' | 'cjs' }) => string;
 
diff --git a/packages/kit/types/private.d.ts b/packages/kit/types/private.d.ts
index f2a74d7b118a..9cd151ad5bb5 100644
--- a/packages/kit/types/private.d.ts
+++ b/packages/kit/types/private.d.ts
@@ -23,7 +23,7 @@ export interface AdapterEntry {
 	 */
 	complete: (entry: {
 		generateManifest: (opts: { relativePath: string; format?: 'esm' | 'cjs' }) => string;
-	}) => void;
+	}) => Promise<void>;
 }
 
 // Based on https://github.com/josh-hemphill/csp-typed-directives/blob/latest/src/csp.types.ts
@@ -250,6 +250,7 @@ export interface ResolveOptions {
 export type ResponseHeaders = Record<string, string | number | string[]>;
 
 export interface RouteDefinition {
+	id: string;
 	type: 'page' | 'endpoint';
 	pattern: RegExp;
 	segments: RouteSegment[];

From 5942d60dcd4fb252fcf4c1351d3f700c292a23bf Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Tue, 19 Apr 2022 16:09:12 -0400
Subject: [PATCH 05/13] WIP edge support

---
 packages/adapter-vercel/files/edge.js         | 16 +++++++
 .../files/{entry.js => serverless.js}         |  4 +-
 packages/adapter-vercel/files/shims.js        |  2 -
 packages/adapter-vercel/index.js              | 43 +++++++++++++++++--
 4 files changed, 59 insertions(+), 6 deletions(-)
 create mode 100644 packages/adapter-vercel/files/edge.js
 rename packages/adapter-vercel/files/{entry.js => serverless.js} (89%)
 delete mode 100644 packages/adapter-vercel/files/shims.js

diff --git a/packages/adapter-vercel/files/edge.js b/packages/adapter-vercel/files/edge.js
new file mode 100644
index 000000000000..87420defc566
--- /dev/null
+++ b/packages/adapter-vercel/files/edge.js
@@ -0,0 +1,16 @@
+import { Server } from 'SERVER';
+import { manifest } from 'MANIFEST';
+
+const server = new Server(manifest);
+
+/**
+ * @param {Request} request
+ * @param {any} event
+ */
+export default (request, event) => {
+	return server.respond(request, {
+		getClientAddress() {
+			return request.headers.get('x-forwarded-for');
+		}
+	});
+};
diff --git a/packages/adapter-vercel/files/entry.js b/packages/adapter-vercel/files/serverless.js
similarity index 89%
rename from packages/adapter-vercel/files/entry.js
rename to packages/adapter-vercel/files/serverless.js
index dcbd3ebcb6bb..9e7285f26e9a 100644
--- a/packages/adapter-vercel/files/entry.js
+++ b/packages/adapter-vercel/files/serverless.js
@@ -1,8 +1,10 @@
-import './shims';
+import { installFetch } from '@sveltejs/kit/install-fetch';
 import { getRequest, setResponse } from '@sveltejs/kit/node';
 import { Server } from 'SERVER';
 import { manifest } from 'MANIFEST';
 
+installFetch();
+
 const server = new Server(manifest);
 
 /**
diff --git a/packages/adapter-vercel/files/shims.js b/packages/adapter-vercel/files/shims.js
deleted file mode 100644
index 8d2fe00acd85..000000000000
--- a/packages/adapter-vercel/files/shims.js
+++ /dev/null
@@ -1,2 +0,0 @@
-import { installFetch } from '@sveltejs/kit/install-fetch';
-installFetch();
diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index 50ad217a2a1b..d5a4adf8eaa2 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -258,7 +258,7 @@ async function v3(builder, external, edge, split) {
 		const tmp = builder.getBuildDirectory(`vercel-tmp/${name}`);
 		const relativePath = posix.relative(tmp, builder.getServerDirectory());
 
-		builder.copy(files, tmp, {
+		builder.copy(`${files}/serverless.js`, `${tmp}/serverless.js`, {
 			replace: {
 				SERVER: `${relativePath}/index.js`,
 				MANIFEST: './manifest.js'
@@ -271,7 +271,7 @@ async function v3(builder, external, edge, split) {
 		);
 
 		await esbuild.build({
-			entryPoints: [`${tmp}/entry.js`],
+			entryPoints: [`${tmp}/serverless.js`],
 			outfile: `${dirs.functions}/${name}.func/index.js`,
 			target: 'node14',
 			bundle: true,
@@ -297,8 +297,45 @@ async function v3(builder, external, edge, split) {
 	/**
 	 * @param {string} name
 	 * @param {string} pattern
+	 * @param {(options: { relativePath: string }) => string} generate_manifest
 	 */
-	async function generate_edge_function(name, pattern) {}
+	async function generate_edge_function(name, pattern, generate_manifest) {
+		const tmp = builder.getBuildDirectory(`vercel-tmp/${name}`);
+		const relativePath = posix.relative(tmp, builder.getServerDirectory());
+
+		builder.copy(`${files}/edge.js`, `${tmp}/edge.js`, {
+			replace: {
+				SERVER: `${relativePath}/index.js`,
+				MANIFEST: './manifest.js'
+			}
+		});
+
+		write(
+			`${tmp}/manifest.js`,
+			`export const manifest = ${generate_manifest({ relativePath })};\n`
+		);
+
+		await esbuild.build({
+			entryPoints: [`${tmp}/edge.js`],
+			outfile: `${dirs.functions}/${name}.func/index.js`,
+			target: 'node14',
+			bundle: true,
+			platform: 'node',
+			format: 'esm',
+			external
+		});
+
+		write(
+			`${dirs.functions}/${name}.func/.vc-config.json`,
+			JSON.stringify({
+				runtime: 'edge',
+				handler: 'index.js'
+				// TODO expose envVarsInUse
+			})
+		);
+
+		routes.push({ src: pattern, dest: name });
+	}
 
 	const generate_function = edge ? generate_edge_function : generate_serverless_function;
 

From 3d8371bb196dddec2816ecfab675321a47fe72b1 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Tue, 19 Apr 2022 16:09:29 -0400
Subject: [PATCH 06/13] DYAC

---
 packages/adapter-vercel/index.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index d5a4adf8eaa2..f63c01a18297 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -1,4 +1,4 @@
-import { fstat, mkdirSync, writeFileSync } from 'fs';
+import { mkdirSync, writeFileSync } from 'fs';
 import { dirname, posix } from 'path';
 import { fileURLToPath } from 'url';
 import esbuild from 'esbuild';

From cfc7319691290a994ecd320ab95be58ce4873b9b Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Tue, 19 Apr 2022 16:21:26 -0400
Subject: [PATCH 07/13] lint

---
 packages/adapter-vercel/files/edge.js | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/packages/adapter-vercel/files/edge.js b/packages/adapter-vercel/files/edge.js
index 87420defc566..cc8cb64370b1 100644
--- a/packages/adapter-vercel/files/edge.js
+++ b/packages/adapter-vercel/files/edge.js
@@ -5,9 +5,8 @@ const server = new Server(manifest);
 
 /**
  * @param {Request} request
- * @param {any} event
  */
-export default (request, event) => {
+export default (request) => {
 	return server.respond(request, {
 		getClientAddress() {
 			return request.headers.get('x-forwarded-for');

From 4880c9c3318ba8ba3ae73368234ebb8d195d5a22 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Tue, 19 Apr 2022 18:08:50 -0400
Subject: [PATCH 08/13] fix config and .vc-config.json

---
 packages/adapter-vercel/index.js | 21 ++-------------------
 1 file changed, 2 insertions(+), 19 deletions(-)

diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index f63c01a18297..ec3c13618d11 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -329,7 +329,7 @@ async function v3(builder, external, edge, split) {
 			`${dirs.functions}/${name}.func/.vc-config.json`,
 			JSON.stringify({
 				runtime: 'edge',
-				handler: 'index.js'
+				entrypoint: 'index.js'
 				// TODO expose envVarsInUse
 			})
 		);
@@ -367,24 +367,7 @@ async function v3(builder, external, edge, split) {
 		JSON.stringify({
 			version: 3,
 			target: 'production',
-			routes: [
-				...redirects[builder.config.kit.trailingSlash],
-				...prerendered_pages,
-				...prerendered_redirects,
-				{
-					src: `/${builder.config.kit.appDir}/.+`,
-					headers: {
-						'cache-control': 'public, immutable, max-age=31536000'
-					}
-				},
-				{
-					handle: 'filesystem'
-				},
-				{
-					src: '/.*',
-					dest: 'render'
-				}
-			]
+			routes
 		})
 	);
 }

From 4a29ef62d9d9716e9da72c68cc24f48c5fdceade Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Wed, 20 Apr 2022 10:14:16 -0400
Subject: [PATCH 09/13] remove catch-all route

---
 packages/adapter-vercel/index.js | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index ec3c13618d11..ca4a74bb2ed4 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -240,10 +240,6 @@ async function v3(builder, external, edge, split) {
 		},
 		{
 			handle: 'filesystem'
-		},
-		{
-			src: '/.*',
-			dest: 'render'
 		}
 	];
 

From 24d7f8ac54a97a1425192ad11ae1a0788ed47a49 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Wed, 20 Apr 2022 12:21:11 -0400
Subject: [PATCH 10/13] fixes

---
 packages/adapter-vercel/index.js | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index ca4a74bb2ed4..3405d8cc07ab 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -228,6 +228,7 @@ async function v3(builder, external, edge, split) {
 		status: redirect.status
 	}));
 
+	/** @type {any[]} */
 	const routes = [
 		...redirects[builder.config.kit.trailingSlash],
 		...prerendered_pages,
@@ -287,7 +288,7 @@ async function v3(builder, external, edge, split) {
 
 		write(`${dirs.functions}/${name}.func/package.json`, JSON.stringify({ type: 'commonjs' }));
 
-		routes.push({ src: pattern, dest: name });
+		routes.push({ src: pattern, dest: `/${name}` });
 	}
 
 	/**
@@ -330,7 +331,7 @@ async function v3(builder, external, edge, split) {
 			})
 		);
 
-		routes.push({ src: pattern, dest: name });
+		routes.push({ src: pattern, middlewarePath: name });
 	}
 
 	const generate_function = edge ? generate_edge_function : generate_serverless_function;
@@ -341,13 +342,17 @@ async function v3(builder, external, edge, split) {
 				id: route.pattern.toString(), // TODO is `id` necessary?
 				filter: (other) => route.pattern.toString() === other.pattern.toString(),
 				complete: async (entry) => {
-					const src = `/${route.pattern}`;
+					const src = `${route.pattern
+						.toString()
+						.slice(1, -2) // remove leading / and trailing $/
+						.replace(/\\\//g, '/')}(?:/__data.json)?$`; // TODO adding /__data.json is a temporary workaround — those endpoints should be treated as distinct routes
+
 					await generate_function(route.id, src, entry.generateManifest);
 				}
 			};
 		});
 	} else {
-		generate_function('render', '/.*', builder.generateManifest);
+		await generate_function('render', '/.*', builder.generateManifest);
 	}
 
 	builder.log.minor('Copying assets...');

From 6b861e73a850390ba1cb19678b47a9204e2b89e4 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Wed, 20 Apr 2022 13:58:41 -0400
Subject: [PATCH 11/13] use overrides for prerendered pages

---
 packages/adapter-vercel/index.js | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/packages/adapter-vercel/index.js b/packages/adapter-vercel/index.js
index 3405d8cc07ab..781586e79f6a 100644
--- a/packages/adapter-vercel/index.js
+++ b/packages/adapter-vercel/index.js
@@ -214,12 +214,6 @@ async function v3(builder, external, edge, split) {
 		functions: `${dir}/functions`
 	};
 
-	// TODO use `overrides` rather than `routes`
-	const prerendered_pages = Array.from(builder.prerendered.pages, ([src, page]) => ({
-		src,
-		dest: page.file
-	}));
-
 	const prerendered_redirects = Array.from(builder.prerendered.redirects, ([src, redirect]) => ({
 		src,
 		headers: {
@@ -231,7 +225,6 @@ async function v3(builder, external, edge, split) {
 	/** @type {any[]} */
 	const routes = [
 		...redirects[builder.config.kit.trailingSlash],
-		...prerendered_pages,
 		...prerendered_redirects,
 		{
 			src: `/${builder.config.kit.appDir}/.+`,
@@ -363,12 +356,19 @@ async function v3(builder, external, edge, split) {
 
 	builder.log.minor('Writing routes...');
 
+	/** @type {Record<string, { path: string }>} */
+	const overrides = {};
+	builder.prerendered.pages.forEach((page, src) => {
+		overrides[page.file] = { path: src.slice(1) };
+	});
+
 	write(
 		`${dir}/config.json`,
 		JSON.stringify({
 			version: 3,
 			target: 'production',
-			routes
+			routes,
+			overrides
 		})
 	);
 }

From ce331e7bafa50c27aff2158b6511a4c9a6aa2108 Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Wed, 20 Apr 2022 14:44:35 -0400
Subject: [PATCH 12/13] update README

---
 packages/adapter-vercel/README.md | 25 +++++++++++++++++--------
 1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/packages/adapter-vercel/README.md b/packages/adapter-vercel/README.md
index 9717b67f17e7..3eb2a525ef7f 100644
--- a/packages/adapter-vercel/README.md
+++ b/packages/adapter-vercel/README.md
@@ -6,6 +6,8 @@ If you're using [adapter-auto](../adapter-auto), you don't need to install this
 
 ## Usage
 
+> The `edge` and `split` options depend on the Vercel Build Output API which is currently in beta. For now, you must opt in by visiting `https://vercel.com/svelte/[YOUR_PROJECT]/settings/environment-variables` and adding `ENABLE_VC_BUILD` with the value `1`.
+
 Add `"@sveltejs/adapter-vercel": "next"` to the `devDependencies` in your `package.json` and run `npm install`.
 
 Then in your `svelte.config.js`:
@@ -15,18 +17,25 @@ import vercel from '@sveltejs/adapter-vercel';
 
 export default {
 	kit: {
-		...
-		adapter: vercel(options)
+		// default options are shown
+		adapter: vercel({
+			// if true, will deploy the app using edge functions
+			// (https://vercel.com/docs/concepts/functions/edge-functions)
+			// rather than serverless functions
+			edge: false,
+
+			// an array of dependencies that esbuild should treat
+			// as external when bundling functions
+			external: [],
+
+			// if true, will split your app into multiple functions
+			// instead of creating a single one for the entire app
+			split: false
+		})
 	}
 };
 ```
 
-## Options
-
-You can pass an `options` argument, if necessary, with the following:
-
-- `external` — an array of dependencies that [esbuild](https://esbuild.github.io/api/#external) should treat as external
-
 ## Changelog
 
 [The Changelog for this package is available on GitHub](https://github.com/sveltejs/kit/blob/master/packages/adapter-vercel/CHANGELOG.md).

From f08755c48111b78824e1edeeb132e17dfe5dd93e Mon Sep 17 00:00:00 2001
From: Rich Harris <hello@rich-harris.dev>
Date: Wed, 20 Apr 2022 14:47:43 -0400
Subject: [PATCH 13/13] changesets

---
 .changeset/giant-ants-hang.md   | 5 +++++
 .changeset/smooth-dodos-clap.md | 5 +++++
 2 files changed, 10 insertions(+)
 create mode 100644 .changeset/giant-ants-hang.md
 create mode 100644 .changeset/smooth-dodos-clap.md

diff --git a/.changeset/giant-ants-hang.md b/.changeset/giant-ants-hang.md
new file mode 100644
index 000000000000..2ed64e81bfcf
--- /dev/null
+++ b/.changeset/giant-ants-hang.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/adapter-vercel': patch
+---
+
+Support build output API, with edge functions and code-splitting
diff --git a/.changeset/smooth-dodos-clap.md b/.changeset/smooth-dodos-clap.md
new file mode 100644
index 000000000000..d45d135122b5
--- /dev/null
+++ b/.changeset/smooth-dodos-clap.md
@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+builder.createEntries returns a promise that awaits complete() callbacks