feat: add configurable build entry point

packages/docs/src/build.ts

@@ -0,0 +1,43 @@
+import { writeFile } from "node:fs/promises";
+import path from "node:path";
+import type { BuildEntryFunction } from "@funstack/static/server";
+import type { RouteDefinition } from "@funstack/router/server";
+import { routes } from "./App";
+
+const siteUrl = "https://static.funstack.work";
+
+function collectPaths(routes: RouteDefinition[]): string[] {
+  const paths: string[] = [];
+  for (const route of routes) {
+    if (route.children) {
+      paths.push(...collectPaths(route.children));
+    } else if (route.path !== undefined && route.path !== "*") {
+      paths.push(route.path);
+    }
+  }
+  return paths;
+}
+
+function generateSitemap(paths: string[]): string {
+  const urls = paths
+    .map((p) => {
+      const loc = p === "/" ? siteUrl + "/" : `${siteUrl}${p}`;
+      return `  <url>\n    <loc>${loc}</loc>\n  </url>`;
+    })
+    .join("\n");
+
+  return `<?xml version="1.0" encoding="UTF-8"?>
+<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
+${urls}
+</urlset>
+`;
+}
+
+export default (async ({ build, outDir }) => {
+  const paths = collectPaths(routes);
+
+  await Promise.all([
+    build(),
+    writeFile(path.join(outDir, "sitemap.xml"), generateSitemap(paths)),
+  ]);
+}) satisfies BuildEntryFunction;

packages/docs/vite.config.ts

@@ -14,6 +14,7 @@ export default defineConfig(async () => {
       funstackStatic({
         entries: "./src/entries.tsx",
         ssr: true,
+        build: "./src/build.ts",
       }),
       {
         // to make .mdx loading lazy

packages/static/src/build/buildApp.ts

@@ -25,55 +25,63 @@ export async function buildApp(
   const baseDir = config.environments.client.build.outDir;
   const base = normalizeBase(config.base);
 
-  const { entries, deferRegistry } = await entry.build();
-
-  // Validate all entry paths
-  const paths: string[] = [];
-  for (const result of entries) {
-    const error = validateEntryPath(result.path);
-    if (error) {
-      throw new Error(error);
+  async function doBuild() {
+    const { entries, deferRegistry } = await entry.build();
+
+    // Validate all entry paths
+    const paths: string[] = [];
+    for (const result of entries) {
+      const error = validateEntryPath(result.path);
+      if (error) {
+        throw new Error(error);
+      }
+      paths.push(result.path);
+    }
+    const dupError = checkDuplicatePaths(paths);
+    if (dupError) {
+      throw new Error(dupError);
     }
-    paths.push(result.path);
-  }
-  const dupError = checkDuplicatePaths(paths);
-  if (dupError) {
-    throw new Error(dupError);
-  }
-
-  // Process all deferred components once across all entries.
-  // We pass a dummy empty stream since we handle per-entry RSC payloads separately.
-  const dummyStream = new ReadableStream<Uint8Array>({
-    start(controller) {
-      controller.close();
-    },
-  });
-  const { components, idMapping } = await processRscComponents(
-    deferRegistry.loadAll(),
-    dummyStream,
-    options.rscPayloadDir,
-    context,
-  );
 
-  // Write each entry's HTML and RSC payload
-  for (const result of entries) {
-    await buildSingleEntry(
-      result,
-      idMapping,
-      baseDir,
-      base,
+    // Process all deferred components once across all entries.
+    // We pass a dummy empty stream since we handle per-entry RSC payloads separately.
+    const dummyStream = new ReadableStream<Uint8Array>({
+      start(controller) {
+        controller.close();
+      },
+    });
+    const { components, idMapping } = await processRscComponents(
+      deferRegistry.loadAll(),
+      dummyStream,
       options.rscPayloadDir,
       context,
     );
+
+    // Write each entry's HTML and RSC payload
+    for (const result of entries) {
+      await buildSingleEntry(
+        result,
+        idMapping,
+        baseDir,
+        base,
+        options.rscPayloadDir,
+        context,
+      );
+    }
+
+    // Write all deferred component payloads
+    for (const { finalId, finalContent, name } of components) {
+      const filePath = path.join(
+        baseDir,
+        getModulePathFor(finalId).replace(/^\//, ""),
+      );
+      await writeFileNormal(filePath, finalContent, context, name);
+    }
   }
 
-  // Write all deferred component payloads
-  for (const { finalId, finalContent, name } of components) {
-    const filePath = path.join(
-      baseDir,
-      getModulePathFor(finalId).replace(/^\//, ""),
-    );
-    await writeFileNormal(filePath, finalContent, context, name);
+  if (entry.buildEntry) {
+    await entry.buildEntry({ build: doBuild, outDir: baseDir });
+  } else {
+    await doBuild();
   }
 }
 

packages/static/src/buildEntryDefinition.ts

@@ -0,0 +1,23 @@
+/**
+ * Context passed to the build entry function.
+ */
+export interface BuildEntryContext {
+  /**
+   * Performs the default build flow (rendering entries and writing output files).
+   * Call this to execute the standard build process.
+   * You can run additional work before, after, or in parallel with this function.
+   */
+  build: () => Promise<void>;
+  /**
+   * Absolute path to the output directory where built files are written.
+   * Use this to write additional files (e.g. sitemap.xml) alongside the build output.
+   */
+  outDir: string;
+}
+
+/**
+ * The build entry module should default-export a function with this signature.
+ */
+export type BuildEntryFunction = (
+  context: BuildEntryContext,
+) => Promise<void> | void;

packages/static/src/entries/server.ts

@@ -1 +1,5 @@
 export { defer, type DeferOptions } from "../rsc/defer";
+export type {
+  BuildEntryContext,
+  BuildEntryFunction,
+} from "../buildEntryDefinition";

packages/static/src/plugin/index.ts

@@ -40,6 +40,19 @@ interface FunstackStaticBaseOptions {
    * @default "fun__rsc-payload"
    */
   rscPayloadDir?: string;
+  /**
+   * Path to a module that customizes the build process.
+   * The module should `export default` an async function that receives
+   * `{ build }` where `build` is a function that performs the default
+   * build flow.
+   *
+   * This allows you to run additional work before/after the build,
+   * or to control the build execution (e.g. parallel work).
+   * Only called during production builds, not in dev mode.
+   *
+   * The module runs in the RSC environment.
+   */
+  build?: string;
 }
 
 interface SingleEntryOptions {
@@ -95,6 +108,7 @@ export default function funstackStatic(
 
   let resolvedEntriesModule: string = "__uninitialized__";
   let resolvedClientInitEntry: string | undefined;
+  let resolvedBuildEntry: string | undefined;
 
   // Determine whether user specified entries or root+app
   const isMultiEntry = "entries" in options && options.entries !== undefined;
@@ -152,6 +166,11 @@ export default function funstackStatic(
             path.resolve(config.root, clientInit),
           );
         }
+        if (options.build) {
+          resolvedBuildEntry = normalizePath(
+            path.resolve(config.root, options.build),
+          );
+        }
       },
       configEnvironment(_name, config) {
         if (!config.optimizeDeps) {
@@ -189,6 +208,9 @@ export default function funstackStatic(
         if (id === "virtual:funstack/client-init") {
           return "\0virtual:funstack/client-init";
         }
+        if (id === "virtual:funstack/build-entry") {
+          return "\0virtual:funstack/build-entry";
+        }
       },
       load(id) {
         if (id === "\0virtual:funstack/entries") {
@@ -218,6 +240,12 @@ export default function funstackStatic(
           }
           return "";
         }
+        if (id === "\0virtual:funstack/build-entry") {
+          if (resolvedBuildEntry) {
+            return `export { default } from "${resolvedBuildEntry}";`;
+          }
+          return "export default undefined;";
+        }
       },
     },
     {

packages/static/src/rsc/entry.tsx

@@ -316,6 +316,7 @@ export async function build() {
 }
 
 export { defer } from "./defer";
+export { default as buildEntry } from "virtual:funstack/build-entry";
 
 if (import.meta.hot) {
   import.meta.hot.accept();

packages/static/src/virtual.d.ts

@@ -8,3 +8,8 @@ declare module "virtual:funstack/config" {
   export const rscPayloadDir: string;
 }
 declare module "virtual:funstack/client-init" {}
+declare module "virtual:funstack/build-entry" {
+  import type { BuildEntryFunction } from "./buildEntryDefinition";
+  const buildEntry: BuildEntryFunction | undefined;
+  export default buildEntry;
+}