feat: merge nitro instances into singular on vercel builds

Signed-off-by: Rihan Arfan <me@file.properties>

Author: RihanArfan

.changeset/single-vercel-nitro-build.md

@@ -0,0 +1,5 @@
+---
+"eve": patch
+---
+
+Vercel builds now run a single Nitro build. The workflow flow function is emitted through Nitro's per-route `functionRules` (queue trigger, `maxDuration: "max"`, precondition guard) instead of a second standalone Nitro build that was copied and retargeted into the output, making `eve build` on Vercel roughly twice as fast.

docs/channels/slack.mdx

@@ -40,7 +40,6 @@ export default slackChannel({
 
 If eve cannot find an authenticated Vercel session, `eve channels add slack` asks whether to set up Vercel Connect or use portable environment credentials. The portable option adds the required names to `.env.example`. Before deploying, appropriate values must be supplied to your runtime environment.
 
-
 ### Deploy
 
 Deploy once the trigger destination and channel file are ready:

packages/eve/src/internal/application/build-workspace.ts

@@ -16,7 +16,6 @@ export interface ApplicationBuildWorkspace {
   };
   readonly nitro: {
     readonly buildDir: string;
-    readonly surfaceOutputDir: string;
   };
   readonly publication: {
     readonly output: {
@@ -59,7 +58,6 @@ export async function createApplicationBuildWorkspace(
     },
     nitro: {
       buildDir: join(rootDir, "nitro"),
-      surfaceOutputDir: join(rootDir, "nitro-output"),
     },
     publication: {
       output: {

packages/eve/src/internal/application/paths.ts

@@ -3,7 +3,6 @@ import { existsSync, readdirSync, readFileSync, rmSync } from "node:fs";
 import { join, resolve } from "node:path";
 
 import { workflowEntryReference } from "#execution/workflow-runtime.js";
-import type { NitroBuildSurface } from "#internal/nitro/host/types.js";
 import {
   resolveInstalledPackageInfo,
   resolvePackageRoot,
@@ -45,33 +44,14 @@ export function isVercelBuildEnvironment(): boolean {
 /**
  * Resolves the programmatic Nitro build directory for an app.
  */
-export function resolveNitroBuildDirectory(
-  appRoot: string,
-  surface: NitroBuildSurface = "all",
-): string {
-  const rootDirectory = join(appRoot, ".eve", "nitro");
-
-  if (surface === "all") {
-    return rootDirectory;
-  }
-
-  return join(rootDirectory, surface);
+export function resolveNitroBuildDirectory(appRoot: string): string {
+  return join(appRoot, ".eve", "nitro");
 }
 
 export function resolveApplicationHostArtifactsDirectory(appRoot: string): string {
   return join(appRoot, ".eve", "host");
 }
 
-/**
- * Resolves the staged Nitro output directory for one isolated build surface.
- */
-export function resolveNitroSurfaceOutputDirectory(
-  appRoot: string,
-  surface: Exclude<NitroBuildSurface, "all">,
-): string {
-  return join(appRoot, ".eve", "nitro-output", surface);
-}
-
 /**
  * Resolves the package-owned Workflow DevKit bundle directory for a target app.
  *

packages/eve/src/internal/nitro/host/build-application.scenario.test.ts

@@ -68,8 +68,6 @@ const resolveDiscoveryProjectMock = vi.fn(async (appRoot: string) => ({
   layout: "nested" as const,
 }));
 const runVercelBuildPrewarmMock = vi.fn(async () => undefined);
-const workflowBuilderBuildVercelOutputMock = vi.fn(async (_options: unknown) => undefined);
-const workflowBuilderConstructors: unknown[] = [];
 
 vi.mock("nitro/builder", () => ({
   build: buildNitroMock,
@@ -94,18 +92,6 @@ vi.mock("./vercel-build-prewarm.js", () => ({
   runVercelBuildPrewarm: runVercelBuildPrewarmMock,
 }));
 
-vi.mock("../../workflow-bundle/builder.js", () => ({
-  WorkflowBundleBuilder: class WorkflowBundleBuilder {
-    constructor(options: unknown) {
-      workflowBuilderConstructors.push(options);
-    }
-
-    async buildVercelOutput(options: unknown): Promise<void> {
-      await workflowBuilderBuildVercelOutputMock(options);
-    }
-  },
-}));
-
 const createScratchDirectory = useTemporaryDirectories();
 const DEPLOYABLE_BUILD_OPTIONS = { skipVercelSandboxPrewarm: false } as const;
 
@@ -177,7 +163,6 @@ describe("buildApplication", () => {
   beforeEach(() => {
     vi.resetModules();
     vi.clearAllMocks();
-    workflowBuilderConstructors.length = 0;
   });
 
   afterEach(() => {
@@ -223,7 +208,6 @@ describe("buildApplication", () => {
         2,
       )}\n`,
     );
-    expect(workflowBuilderBuildVercelOutputMock).not.toHaveBeenCalled();
     expect(runVercelBuildPrewarmMock).not.toHaveBeenCalled();
     await expect(
       readFile(join(appRoot, ".eve", "compile", "compiled-agent-manifest.json"), "utf8"),
@@ -265,7 +249,7 @@ describe("buildApplication", () => {
     expect(profile.phases).toEqual(
       expect.arrayContaining([
         expect.objectContaining({ name: "host.prepare" }),
-        expect.objectContaining({ name: "nitro.all.bundle" }),
+        expect.objectContaining({ name: "nitro.bundle" }),
         expect.objectContaining({ name: "output.publish" }),
         expect.objectContaining({ name: "workspace.remove" }),
       ]),
@@ -384,27 +368,17 @@ describe("buildApplication", () => {
     await expect(readFile(summaryPath, "utf8")).resolves.toBe("last-good-summary\n");
   });
 
-  it("builds isolated Vercel Nitro surfaces and stitches workflow functions", async () => {
+  it("builds one Vercel Nitro output and normalizes eve functions", async () => {
     vi.stubEnv("VERCEL", "1");
     const appRoot = await createScratchDirectory("eve-build-application-vercel-");
     const profilePath = join(appRoot, ".eve", "profiles", "vercel-build.json");
-    const stableFlowOutputDir = join(appRoot, ".eve", "nitro-output", "flow");
-    const staleFlowOutputPath = join(stableFlowOutputDir, "stale-flow.txt");
 
     prepareProductionApplicationHostMock.mockImplementationOnce(prepareHostBuildWorkspace);
     createProductionApplicationNitroMock.mockImplementation(
       async (_preparedHost: PreparedApplicationHost, options: { outputDir: string }) =>
         createNitroStub(options.outputDir),
     );
-    await mkdir(stableFlowOutputDir, { recursive: true });
-    await Promise.all([
-      writeFile(
-        join(stableFlowOutputDir, "eve-cache.json"),
-        `${JSON.stringify({ eveVersion: "old" })}\n`,
-      ),
-      writeFile(staleFlowOutputPath, "stale\n"),
-      mkdir(join(appRoot, ".vercel", "output"), { recursive: true }),
-    ]);
+    await mkdir(join(appRoot, ".vercel", "output"), { recursive: true });
     await writeFile(
       join(appRoot, ".vercel", "output", "config.json"),
       `${JSON.stringify(
@@ -437,20 +411,14 @@ describe("buildApplication", () => {
     });
 
     expect(outputDir).toBe(join(appRoot, ".vercel", "output"));
-    expect(createProductionApplicationNitroMock).toHaveBeenCalledTimes(2);
-    expect(createProductionApplicationNitroMock.mock.calls.map((call) => call[1]?.surface)).toEqual(
-      ["app", "flow"],
-    );
-    const flowOutputDir = createProductionApplicationNitroMock.mock.calls.find(
-      (call) => call[1]?.surface === "flow",
-    )?.[1]?.outputDir;
-    expect(flowOutputDir).toEqual(expect.stringContaining(join(appRoot, ".eve", "builds")));
-    expect(workflowBuilderConstructors).toHaveLength(1);
-    expect(workflowBuilderBuildVercelOutputMock).toHaveBeenCalledWith({
-      flowNitroOutputDir: flowOutputDir,
-      outputDir: expect.stringContaining(join(appRoot, ".eve", "builds")),
-      runtime: "nodejs24.x",
-    });
+    expect(createProductionApplicationNitroMock).toHaveBeenCalledTimes(1);
+    expect(createProductionApplicationNitroMock).toHaveBeenCalledWith(
+      expect.objectContaining({ appRoot }),
+      {
+        buildDir: expect.stringContaining(join(appRoot, ".eve", "builds")),
+        outputDir: expect.stringContaining(join(appRoot, ".eve", "builds")),
+      },
+    );
     const nestedFunctionStats = await lstat(
       join(appRoot, ".vercel", "output", "functions", "eve", "v1", "health.func"),
     );
@@ -491,7 +459,6 @@ describe("buildApplication", () => {
         src: "^/eve/v1/session/(?<sessionId>[^/]+)/stream$",
       },
     ]);
-    await expect(readFile(staleFlowOutputPath, "utf8")).resolves.toBe("stale\n");
     expect(runVercelBuildPrewarmMock).toHaveBeenCalledWith(
       expect.objectContaining({
         appRoot,
@@ -533,20 +500,18 @@ describe("buildApplication", () => {
 
     expect(outputDir).toBe(join(appRoot, ".vercel", "output"));
     expect(runVercelBuildPrewarmMock).not.toHaveBeenCalled();
-    expect(workflowBuilderBuildVercelOutputMock).toHaveBeenCalledTimes(1);
+    expect(buildNitroMock).toHaveBeenCalledTimes(1);
   });
 
   it("normalizes eve function output behind a non-Next host service", async () => {
     vi.stubEnv("VERCEL", "1");
     const appRoot = await createScratchDirectory("eve-build-application-vercel-nuxt-");
-    const flowOutputDir = join(appRoot, ".eve", "nitro-output", "flow");
 
     prepareProductionApplicationHostMock.mockImplementationOnce(prepareHostBuildWorkspace);
     createProductionApplicationNitroMock.mockImplementation(
       async (_preparedHost: PreparedApplicationHost, options: { outputDir: string }) =>
         createNitroStub(options.outputDir),
     );
-    await mkdir(flowOutputDir, { recursive: true });
     await writeFile(
       join(appRoot, "vercel.json"),
       `${JSON.stringify(
@@ -705,40 +670,36 @@ describe("buildApplication", () => {
     });
   });
 
-  it("builds isolated Vercel Nitro surfaces from legacy root service config", async () => {
+  it("normalizes eve function output from legacy root service config", async () => {
     vi.stubEnv("VERCEL", "1");
     const appRoot = await createScratchDirectory("eve-build-application-vercel-root-config-");
-    const flowOutputDir = join(appRoot, ".eve", "nitro-output", "flow");
 
     prepareProductionApplicationHostMock.mockImplementationOnce(prepareHostBuildWorkspace);
     createProductionApplicationNitroMock.mockImplementation(
       async (_preparedHost: PreparedApplicationHost, options: { outputDir: string }) =>
         createNitroStub(options.outputDir),
     );
-    await Promise.all([
-      mkdir(flowOutputDir, { recursive: true }),
-      writeFile(
-        join(appRoot, "vercel.json"),
-        `${JSON.stringify(
-          {
-            experimentalServices: {
-              eve: {
-                entrypoint: ".",
-                framework: "eve",
-                routePrefix: "/_eve_internal/eve",
-              },
-              web: {
-                entrypoint: ".",
-                framework: "nextjs",
-                routePrefix: "/",
-              },
+    await writeFile(
+      join(appRoot, "vercel.json"),
+      `${JSON.stringify(
+        {
+          experimentalServices: {
+            eve: {
+              entrypoint: ".",
+              framework: "eve",
+              routePrefix: "/_eve_internal/eve",
+            },
+            web: {
+              entrypoint: ".",
+              framework: "nextjs",
+              routePrefix: "/",
             },
           },
-          null,
-          2,
-        )}\n`,
-      ),
-    ]);
+        },
+        null,
+        2,
+      )}\n`,
+    );
 
     const { buildApplication } = await import("#internal/nitro/host/build-application.js");
     const outputDir = await buildApplication(appRoot, DEPLOYABLE_BUILD_OPTIONS);