Fix build lags

dist/commands/build/index.js

@@ -3,7 +3,6 @@ import { log } from "../../utils/log";
 import grabDirNames from "../../utils/grab-dir-names";
 import { rmSync, writeFileSync } from "fs";
 import bunextInit from "../../functions/bunext-init";
-import pagesSSRBundler from "../../functions/bundler/pages-ssr-bundler";
 import { v4 } from "uuid";
 const { HYDRATION_DST_DIR, BUNX_CWD_PAGES_REWRITE_DIR, BUNDLER_CTX_MAP_JSON, SSR_BUNDLER_CTX_MAP_JSON, BUNX_CWD_MODULE_CACHE_DIR, BUILD_INFO_JSON, } = grabDirNames();
 export default function () {
@@ -21,7 +20,6 @@ export default function () {
         catch (error) { }
         global.BUNEXT_SKIPPED_BROWSER_MODULES = new Set();
         await bunextInit({ build_only: true });
-        // await pagesSSRBundler();
         // A failed bundle must fail the command: CI and scripts rely on
         // the exit code instead of grepping logs.
         if (global.BUNEXT_BUILD_FAILED) {

dist/functions/bundler/all-pages-esbuild-context-bundler.d.ts

@@ -2,6 +2,7 @@ import type { BundlerCTXMap } from "../../types";
 type Params = {
     post_build_fn?: (params: {
         artifacts: BundlerCTXMap[];
+        changed_pages?: string[];
     }) => Promise<void> | void;
     build_only?: boolean;
     start?: boolean;

dist/functions/bundler/all-pages-esbuild-context-bundler.js

@@ -9,9 +9,23 @@ import virtualFilesPlugin from "./plugins/virtual-files-plugin";
 import esbuildCTXArtifactTracker from "./plugins/esbuild-ctx-artifact-tracker";
 import { logBuildErrorsOnce, } from "../../utils/build-error-log";
 import { log } from "../../utils/log";
+import grabRootFilePath from "../server/web-pages/grab-root-file-path";
 const { HYDRATION_DST_DIR, BUNX_HYDRATION_SRC_DIR } = grabDirNames();
+// Snapshot of the entry key set + root file presence of the last build.
+// When it differs from the freshly computed set, the esbuild context must
+// be recreated (entry points are fixed at context creation).
+let last_entry_keys = undefined;
+let last_root_file_path = undefined;
+function arraysEqual(a, b) {
+    if (a.length !== b.length)
+        return false;
+    for (let i = 0; i < a.length; i++) {
+        if (a[i] !== b[i])
+            return false;
+    }
+    return true;
+}
 export default async function allPagesESBuildContextBundler(params) {
-    const _t0 = Date.now();
     try {
         const pages = grabAllPages({ exclude_api: true });
         global.BUNEXT_PAGE_FILES = pages;
@@ -25,13 +39,22 @@ export default async function allPagesESBuildContextBundler(params) {
                 continue;
             }
             const entryFile = path.join(BUNX_HYDRATION_SRC_DIR, `${page.url_path}.tsx`);
-            // await Bun.write(entryFile, txt, { createPath: true });
             entryToPage.set(entryFile, { ...page, tsx });
         }
         const entryPoints = [...entryToPage.keys()].map((e) => `hydration-virtual:${e}`);
-        // This is a brand-new context: wipe the previous context's failure
+        const entry_keys = [...entryToPage.keys()].sort();
-        // history so the "2 failed starts => dispose" guard starts fresh.
+        const { root_file_path } = grabRootFilePath();
-        global.BUNEXT_MAIN_CTX_BUILD_STARTS = 0;
+        const structure_changed = !global.BUNEXT_BUNDLER_CTX ||
+            global.BUNEXT_BUNDLER_CTX_DISPOSED ||
+            !last_entry_keys ||
+            !arraysEqual(last_entry_keys, entry_keys) ||
+            last_root_file_path !== root_file_path;
+        if (structure_changed) {
+            try {
+                await global.BUNEXT_BUNDLER_CTX?.dispose();
+            }
+            catch (error) { }
+            global.BUNEXT_BUNDLER_CTX = undefined;
             global.BUNEXT_BUNDLER_CTX = await esbuild.context({
                 entryPoints,
                 outdir: HYDRATION_DST_DIR,
@@ -72,6 +95,9 @@ export default async function allPagesESBuildContextBundler(params) {
                 // artifact-tracker plugin reports errors (deduped, once) itself.
                 logLevel: "silent",
             });
+            last_entry_keys = entry_keys;
+            last_root_file_path = root_file_path;
+        }
         await global.BUNEXT_BUNDLER_CTX.rebuild();
     }
     catch (error) {

dist/functions/bundler/pages-ssr-bundler.d.ts

@@ -1,7 +0,0 @@
-type Params = {
-    post_build_fn?: (params: {
-        artifacts: any[];
-    }) => Promise<void> | void;
-};
-export default function pagesSSRBundler(params?: Params): Promise<void>;
-export {};

dist/functions/bundler/pages-ssr-bundler.js

@@ -1,101 +0,0 @@
-import * as esbuild from "esbuild";
-import grabAllPages from "../../utils/grab-all-pages";
-import grabDirNames from "../../utils/grab-dir-names";
-import isDevelopment from "../../utils/is-development";
-import tailwindEsbuildPlugin from "../server/web-pages/tailwind-esbuild-plugin";
-import grabPageReactComponentString from "../server/web-pages/grab-page-react-component-string";
-import grabRootFilePath from "../server/web-pages/grab-root-file-path";
-import ssrVirtualFilesPlugin from "./plugins/ssr-virtual-files-plugin";
-import ssrCTXArtifactTracker from "./plugins/ssr-ctx-artifact-tracker";
-import { writeFileSync } from "fs";
-import path from "path";
-import { log } from "../../utils/log";
-import { logBuildErrorsOnce, } from "../../utils/build-error-log";
-const { BUNX_CWD_MODULE_CACHE_DIR, BUNX_TMP_DIR } = grabDirNames();
-export default async function pagesSSRBundler(params) {
-    const pages = grabAllPages({
-        include_server: true,
-    });
-    const dev = isDevelopment();
-    const config = global.BUNEXT_CONFIG;
-    try {
-        writeFileSync(path.join(BUNX_TMP_DIR, "ssr-pages.json"), JSON.stringify(pages, null, 4));
-    }
-    catch (error) { }
-    const entryToPage = new Map();
-    const { root_file_path } = grabRootFilePath();
-    for (const page of pages) {
-        if (page.local_path.match(/\/pages\/api\//) ||
-            page.local_path.match(/\.server\.tsx?$/)) {
-            const ts = await Bun.file(page.local_path).text();
-            if (ts.match(/(export default)|(export \w+ handler)|(export \w+ server)/)) {
-                entryToPage.set(page.local_path, { ...page, tsx: ts });
-            }
-            continue;
-        }
-        const tsx = grabPageReactComponentString({
-            file_path: page.local_path,
-            root_file_path,
-        });
-        if (!tsx)
-            continue;
-        if (!tsx.match(/export default/))
-            continue;
-        entryToPage.set(page.local_path, { ...page, tsx });
-    }
-    const entryPoints = [...entryToPage.keys()].map((e) => `ssr-virtual:${e}`);
-    try {
-        writeFileSync(path.join(BUNX_TMP_DIR, "ssr-entry-to-page.json"), JSON.stringify(Object(entryToPage), null, 4));
-        writeFileSync(path.join(BUNX_TMP_DIR, "ssr-entrypoints.json"), JSON.stringify(entryPoints, null, 4));
-    }
-    catch (error) { }
-    try {
-        await esbuild.build({
-            entryPoints,
-            outdir: BUNX_CWD_MODULE_CACHE_DIR,
-            bundle: true,
-            minify: !dev,
-            format: "esm",
-            target: "esnext",
-            platform: "node",
-            define: {
-                "process.env.NODE_ENV": JSON.stringify(dev ? "development" : "production"),
-            },
-            entryNames: "[dir]/[hash]",
-            metafile: true,
-            plugins: [
-                tailwindEsbuildPlugin,
-                ssrVirtualFilesPlugin({
-                    entryToPage,
-                }),
-                ssrCTXArtifactTracker({
-                    entryToPage,
-                    post_build_fn: params?.post_build_fn,
-                }),
-            ],
-            jsx: "automatic",
-            external: [
-                "react",
-                "react-dom",
-                "react/jsx-runtime",
-                "react/jsx-dev-runtime",
-                "bun:*",
-                "bun",
-                "sqlite-vec",
-                "better-sqlite3",
-                ...(config.ssr_compiler_excludes || []),
-            ],
-            splitting: true,
-            logLevel: "silent",
-        });
-    }
-    catch (error) {
-        global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED = true;
-        global.BUNEXT_BUILD_FAILED = true;
-        logBuildErrorsOnce([
-            {
-                text: `SSR Bundler Error: ${error?.message || String(error)}`,
-            },
-        ], (line) => log.error(line));
-    }
-}

dist/functions/bundler/pages-ssr-context-bundler.d.ts

@@ -1,7 +1,18 @@
-type Params = {
+type RebuildParams = {
-    post_build_fn?: (params: {
+    /**
-        artifacts: any[];
+     * Force a context recreation even when the entry set is unchanged.
-    }) => Promise<void> | void;
+     * Used by `fullRebuild` after it disposed the contexts.
+     */
+    force?: boolean;
 };
-export default function pagesSSRContextBundler(params?: Params): Promise<void>;
+/**
+ * Single-flight SSR rebuild. Concurrent callers (each successful hydration
+ * rebuild triggers this, plus watcher/structural paths) join the in-flight
+ * rebuild instead of spawning overlapping esbuild builds.
+ *
+ * A fresh content change that lands while a rebuild is in flight is picked
+ * up by the next hydration rebuild cycle (each watcher event re-runs the
+ * hydration context rebuild, which re-enters this queue).
+ */
+export default function enqueueSSRRebuild(params?: RebuildParams): Promise<void>;
 export {};

dist/functions/bundler/pages-ssr-context-bundler.js

@@ -7,20 +7,49 @@ import grabPageReactComponentString from "../server/web-pages/grab-page-react-co
 import grabRootFilePath from "../server/web-pages/grab-root-file-path";
 import ssrVirtualFilesPlugin from "./plugins/ssr-virtual-files-plugin";
 import ssrCTXArtifactTracker from "./plugins/ssr-ctx-artifact-tracker";
-const { BUNX_CWD_MODULE_CACHE_DIR } = grabDirNames();
+import cleanupArtifacts from "../server/cleanup-artifacts";
-export default async function pagesSSRContextBundler(params) {
+import { writeFileSync } from "fs";
-    const pages = grabAllPages();
+import path from "path";
-    const dev = isDevelopment();
+import { log } from "../../utils/log";
-    if (global.BUNEXT_SSR_BUNDLER_CTX) {
+import { logBuildErrorsOnce, } from "../../utils/build-error-log";
-        await global.BUNEXT_SSR_BUNDLER_CTX.dispose();
+const { BUNX_CWD_MODULE_CACHE_DIR, BUNX_TMP_DIR } = grabDirNames();
-        global.BUNEXT_SSR_BUNDLER_CTX = undefined;
+// Current virtual entry contents. The SSR virtual plugin resolves its
+// onLoad contents lazily from this map on every rebuild, so edits to
+// `.server.ts`/api files (whose entries mirror their raw file content) are
+// picked up without recreating the esbuild context.
+let current_entry_map = new Map();
+// Entry key set + root file presence of the last *successful* build. When
+// this differs from the freshly computed set, the context must be
+// recreated (esbuild cannot add/remove entry points on a live context).
+let last_entry_keys = undefined;
+let last_root_file_path = undefined;
+let rebuild_in_flight;
+function arraysEqual(a, b) {
+    if (a.length !== b.length)
+        return false;
+    for (let i = 0; i < a.length; i++) {
+        if (a[i] !== b[i])
+            return false;
     }
-    const entryToPage = new Map();
+    return true;
+}
+async function computeEntryToPage() {
+    const pages = grabAllPages({
+        include_server: true,
+    });
     const { root_file_path } = grabRootFilePath();
+    const entryToPage = new Map();
+    try {
+        writeFileSync(path.join(BUNX_TMP_DIR, "ssr-pages.json"), JSON.stringify(pages, null, 4));
+    }
+    catch (error) { }
     for (const page of pages) {
-        if (page.local_path.match(/\/pages\/api\//)) {
+        if (page.local_path.match(/\/pages\/api\//) ||
+            page.local_path.match(/\.server\.tsx?$/)) {
             const ts = await Bun.file(page.local_path).text();
+            if (ts.match(/(export default)|(export \w+ handler)|(export \w+ server)/)) {
                 entryToPage.set(page.local_path, { ...page, tsx: ts });
+            }
             continue;
         }
         const tsx = grabPageReactComponentString({
@@ -29,9 +58,67 @@ export default async function pagesSSRContextBundler(params) {
         });
         if (!tsx)
             continue;
+        if (!tsx.match(/export default/))
+            continue;
         entryToPage.set(page.local_path, { ...page, tsx });
     }
+    return { entryToPage, root_file_path };
+}
+/**
+ * Single-flight SSR rebuild. Concurrent callers (each successful hydration
+ * rebuild triggers this, plus watcher/structural paths) join the in-flight
+ * rebuild instead of spawning overlapping esbuild builds.
+ *
+ * A fresh content change that lands while a rebuild is in flight is picked
+ * up by the next hydration rebuild cycle (each watcher event re-runs the
+ * hydration context rebuild, which re-enters this queue).
+ */
+export default async function enqueueSSRRebuild(params) {
+    if (rebuild_in_flight) {
+        return rebuild_in_flight;
+    }
+    const run = doSSRRebuild(params).finally(() => {
+        if (rebuild_in_flight === run) {
+            rebuild_in_flight = undefined;
+        }
+    });
+    rebuild_in_flight = run;
+    return run;
+}
+async function doSSRRebuild(params) {
+    const force = Boolean(params?.force);
+    const dev = isDevelopment();
+    const config = global.BUNEXT_CONFIG;
+    try {
+        const { entryToPage, root_file_path } = await computeEntryToPage();
+        const entry_keys = [...entryToPage.keys()].sort();
+        if (entry_keys.length === 0) {
+            current_entry_map = entryToPage;
+            last_entry_keys = entry_keys;
+            last_root_file_path = root_file_path;
+            return;
+        }
+        // Refresh the virtual contents BEFORE rebuilding so the plugin's
+        // onLoad sees the latest `.server.ts`/api contents.
+        current_entry_map = entryToPage;
         const entryPoints = [...entryToPage.keys()].map((e) => `ssr-virtual:${e}`);
+        try {
+            writeFileSync(path.join(BUNX_TMP_DIR, "ssr-entry-to-page.json"), JSON.stringify(Object(entryToPage), null, 4));
+            writeFileSync(path.join(BUNX_TMP_DIR, "ssr-entrypoints.json"), JSON.stringify(entryPoints, null, 4));
+        }
+        catch (error) { }
+        const structure_changed = !global.BUNEXT_SSR_BUNDLER_CTX ||
+            global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED ||
+            force ||
+            !last_entry_keys ||
+            !arraysEqual(last_entry_keys, entry_keys) ||
+            last_root_file_path !== root_file_path;
+        if (structure_changed) {
+            try {
+                await global.BUNEXT_SSR_BUNDLER_CTX?.dispose();
+            }
+            catch (error) { }
+            global.BUNEXT_SSR_BUNDLER_CTX = undefined;
             global.BUNEXT_SSR_BUNDLER_CTX = await esbuild.context({
                 entryPoints,
                 outdir: BUNX_CWD_MODULE_CACHE_DIR,
@@ -48,11 +135,10 @@ export default async function pagesSSRContextBundler(params) {
                 plugins: [
                     tailwindEsbuildPlugin,
                     ssrVirtualFilesPlugin({
-                entryToPage,
+                        getEntryToPage: () => current_entry_map,
                     }),
                     ssrCTXArtifactTracker({
                         entryToPage,
-                post_build_fn: params?.post_build_fn,
                     }),
                 ],
                 jsx: "automatic",
@@ -62,8 +148,35 @@ export default async function pagesSSRContextBundler(params) {
                     "react/jsx-runtime",
                     "react/jsx-dev-runtime",
                     "bun:*",
+                    "bun",
+                    "sqlite-vec",
+                    "better-sqlite3",
+                    ...(config.ssr_compiler_excludes || []),
                 ],
-        // logLevel: "silent",
+                splitting: true,
+                logLevel: "silent",
             });
+        }
         await global.BUNEXT_SSR_BUNDLER_CTX.rebuild();
+        // Only record the entry set after a successful build so a failed
+        // build retries with a fresh context next time.
+        last_entry_keys = entry_keys;
+        last_root_file_path = root_file_path;
+        global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED = false;
+        global.BUNEXT_BUILD_FAILED = false;
+        await cleanupArtifacts({ paradigm: "ssr" });
+    }
+    catch (error) {
+        global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED = true;
+        global.BUNEXT_BUILD_FAILED = true;
+        // esbuild errors are reported (deduped) by the ssr artifact tracker's
+        // onEnd; only re-log unexpected failures.
+        if (!String(error?.message || "").startsWith("Build failed with")) {
+            logBuildErrorsOnce([
+                {
+                    text: `SSR Bundler Error: ${error?.message || String(error)}`,
+                },
+            ], (line) => log.error(line));
+        }
+    }
 }

dist/functions/bundler/plugins/esbuild-ctx-artifact-tracker.d.ts

@@ -6,6 +6,7 @@ type Params = {
     }>;
     post_build_fn?: (params: {
         artifacts: any[];
+        changed_pages?: string[];
     }) => Promise<void> | void;
     build_only?: boolean;
 };

dist/functions/bundler/plugins/esbuild-ctx-artifact-tracker.js

@@ -1,31 +1,24 @@
 import {} from "esbuild";
 import { log } from "../../../utils/log";
 import grabArtifactsFromBundledResults from "../grab-artifacts-from-bundled-result";
-import buildOnstartErrorHandler from "../build-on-start-error-handler";
 import _ from "lodash";
-import pagesSSRBundler from "../pages-ssr-bundler";
+import enqueueSSRRebuild from "../pages-ssr-context-bundler";
 import grabDirNames from "../../../utils/grab-dir-names";
 import { logBuildErrorsOnce, resetBuildErrorLog, } from "../../../utils/build-error-log";
-import { cpSync, existsSync, mkdirSync, rmSync, writeFileSync } from "fs";
+import { cpSync, existsSync, mkdirSync, rmSync } from "fs";
 import fullRebuild from "../../server/full-rebuild";
 import path from "path";
 import cleanupLogsDirs from "../../cleanup-logs-dir";
 import grabRelativePath from "../../../utils/grab-relative-path";
-const { BUNX_BUNDLER_ERROR_EXIT_FILE, BUNX_ERROR_LOGS_DIR, ROOT_DIR } = grabDirNames();
+import cleanupArtifacts from "../../server/cleanup-artifacts";
+const { BUNX_BUNDLER_ERROR_EXIT_FILE, BUNX_ERROR_LOGS_DIR } = grabDirNames();
 let build_start = 0;
-const MAX_BUILD_STARTS = 2;
 export default function esbuildCTXArtifactTracker({ entryToPage, post_build_fn, build_only, }) {
     const artifactTracker = {
         name: "artifact-tracker",
         setup(build) {
             build.onStart(async () => {
-                global.BUNEXT_MAIN_CTX_BUILD_STARTS++;
                 build_start = performance.now();
-                const does_error_file_exist = existsSync(BUNX_BUNDLER_ERROR_EXIT_FILE);
-                if (global.BUNEXT_MAIN_CTX_BUILD_STARTS >= MAX_BUILD_STARTS &&
-                    !does_error_file_exist) {
-                    await buildOnstartErrorHandler();
-                }
             });
             build.onEnd(async (result) => {
                 if (result.errors.length > 0) {
@@ -50,14 +43,28 @@ export default function esbuildCTXArtifactTracker({ entryToPage, post_build_fn,
                     result,
                     entryToPage,
                 });
+                // Pages whose entry output hash changed since the previous
+                // build. With `splitting`, a change to any shared chunk also
+                // re-hashes every page entry that imports it, so this set
+                // covers all pages whose client graph actually changed.
+                const changed_pages = [];
                 if (artifacts?.[0] && artifacts.length > 0) {
                     for (let i = 0; i < artifacts.length; i++) {
                         const artifact = artifacts[i];
                         if (artifact?.local_path &&
                             global.BUNEXT_BUNDLER_CTX_MAP) {
                             const relative_path = grabRelativePath(artifact.local_path);
+                            const prior = global.BUNEXT_BUNDLER_CTX_MAP[relative_path];
+                            if (!prior?.path ||
+                                prior.path !== artifact.path ||
+                                prior.css_path !== artifact.css_path) {
+                                changed_pages.push(relative_path);
+                            }
                             global.BUNEXT_BUNDLER_CTX_MAP[relative_path] =
-                                _.merge(global.BUNEXT_BUNDLER_CTX_MAP[relative_path], { ...artifact, local_path: relative_path });
+                                _.merge(prior, {
+                                    ...artifact,
+                                    local_path: relative_path,
+                                });
                         }
                     }
                 }
@@ -70,13 +77,15 @@ export default function esbuildCTXArtifactTracker({ entryToPage, post_build_fn,
                     logBuildErrorsOnce(result.warnings, (line) => log.warn(line));
                 }
                 global.BUNEXT_BUILD_FAILED = false;
-                global.BUNEXT_MAIN_CTX_BUILD_STARTS = 0;
                 global.BUNEXT_BUNDLER_CTX_DISPOSED = false;
                 const does_error_file_exist = existsSync(BUNX_BUNDLER_ERROR_EXIT_FILE);
-                // SSR must finish before HMR so server props are fresh
+                // SSR must finish before HMR so server props are fresh.
+                // The rebuild is single-flighted: concurrent hydration
+                // rebuilds join the in-flight SSR rebuild instead of
+                // starting overlapping ones.
                 if (build_only) {
                     try {
-                        await pagesSSRBundler();
+                        await enqueueSSRRebuild();
                     }
                     catch (error) {
                         log.error(`SSR Bundler Error: ${error}`);
@@ -91,20 +100,25 @@ export default function esbuildCTXArtifactTracker({ entryToPage, post_build_fn,
                 }
                 else {
                     try {
-                        await pagesSSRBundler();
+                        await enqueueSSRRebuild();
                     }
                     catch (error) {
                         log.error(`SSR Bundler Error: ${error}`);
                     }
                     if (artifacts?.[0] && artifacts.length > 0) {
                         try {
-                            await post_build_fn?.({ artifacts });
+                            await post_build_fn?.({
+                                artifacts,
+                                changed_pages,
+                            });
                         }
                         catch (error) {
                             log.error(`Post-build Error: ${error}`);
                         }
                     }
                 }
+                // Prune orphaned entry outputs from previous rebuilds.
+                await cleanupArtifacts({ paradigm: "hydration" });
                 global.BUNEXT_RECOMPILING = false;
                 global.BUNEXT_IS_SERVER_COMPONENT = false;
             });

dist/functions/bundler/plugins/ssr-ctx-artifact-tracker.d.ts

@@ -4,9 +4,6 @@ type Params = {
     entryToPage: Map<string, PageFiles & {
         tsx: string;
     }>;
-    post_build_fn?: (params: {
-        artifacts: any[];
-    }) => Promise<void> | void;
 };
-export default function ssrCTXArtifactTracker({ entryToPage, post_build_fn, }: Params): Plugin;
+export default function ssrCTXArtifactTracker({ entryToPage }: Params): Plugin;
 export {};

dist/functions/bundler/plugins/ssr-ctx-artifact-tracker.js

@@ -7,32 +7,18 @@ import grabRelativePath from "../../../utils/grab-relative-path";
 import { logBuildErrorsOnce, resetBuildErrorLog, } from "../../../utils/build-error-log";
 import { log } from "../../../utils/log";
 let build_start = 0;
-let build_starts = 0;
-const MAX_BUILD_STARTS = 2;
 const { BUNX_TMP_DIR, ROOT_DIR } = grabDirNames();
-export default function ssrCTXArtifactTracker({ entryToPage, post_build_fn, }) {
+export default function ssrCTXArtifactTracker({ entryToPage }) {
     const artifactTracker = {
         name: "ssr-artifact-tracker",
         setup(build) {
             build.onStart(async () => {
-                build_starts++;
                 build_start = performance.now();
-                if (build_starts == MAX_BUILD_STARTS) {
-                    global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED = true;
-                    await global.BUNEXT_SSR_BUNDLER_CTX?.dispose();
-                    global.BUNEXT_SSR_BUNDLER_CTX = undefined;
-                }
             });
             build.onEnd(async (result) => {
                 if (result.errors.length > 0) {
                     global.BUNEXT_BUILD_FAILED = true;
                     global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED = true;
-                    try {
-                        await global.BUNEXT_SSR_BUNDLER_CTX?.dispose();
-                    }
-                    catch { }
-                    global.BUNEXT_SSR_BUNDLER_CTX = undefined;
-                    build_starts = 0;
                     logBuildErrorsOnce(result.errors, (line) => log.error(`SSR Build error: ${line}`));
                     return;
                 }
@@ -53,16 +39,13 @@ export default function ssrCTXArtifactTracker({ entryToPage, post_build_fn, }) {
                             };
                         }
                     }
-                    // post_build_fn?.({ artifacts });
-                    // const elapsed = (performance.now() - build_start).toFixed(
-                    //     0,
-                    // );
-                    // log.success(`SSR [Built] in ${elapsed}ms`);
                 }
                 try {
                     writeFileSync(path.join(BUNX_TMP_DIR, "ctx-map.json"), JSON.stringify(global.BUNEXT_SSR_BUNDLER_CTX_MAP, null, 4));
                 }
                 catch (error) { }
+                const elapsed = (performance.now() - build_start).toFixed(0);
+                log.success(`SSR [Built] in ${elapsed}ms`);
                 global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED = false;
                 global.BUNEXT_BUILD_FAILED = false;
                 resetBuildErrorLog();

dist/functions/bundler/plugins/ssr-virtual-files-plugin.d.ts

@@ -1,9 +1,16 @@
 import type { Plugin } from "esbuild";
 import type { PageFiles } from "../../../types";
-type Params = {
+type SSRVirtualEntry = PageFiles & {
-    entryToPage: Map<string, PageFiles & {
     tsx: string;
-    }>;
 };
-export default function ssrVirtualFilesPlugin({ entryToPage }: Params): Plugin;
+type Params = {
+    /**
+     * Lazily-resolved current virtual entry contents. The map is refreshed
+     * before every rebuild so edits to `.server.ts`/api files (whose virtual
+     * entries mirror their raw file content) are picked up by a plain
+     * `ctx.rebuild()` without recreating the esbuild context.
+     */
+    getEntryToPage: () => Map<string, SSRVirtualEntry>;
+};
+export default function ssrVirtualFilesPlugin({ getEntryToPage }: Params): Plugin;
 export {};

dist/functions/bundler/plugins/ssr-virtual-files-plugin.js

@@ -1,6 +1,5 @@
 import path from "path";
-import { log } from "../../../utils/log";
+export default function ssrVirtualFilesPlugin({ getEntryToPage }) {
-export default function ssrVirtualFilesPlugin({ entryToPage }) {
     const virtualPlugin = {
         name: "ssr-virtual-hydration",
         setup(build) {
@@ -12,7 +11,7 @@ export default function ssrVirtualFilesPlugin({ entryToPage }) {
                 };
             });
             build.onLoad({ filter: /.*/, namespace: "ssr-virtual" }, (args) => {
-                const target = entryToPage.get(args.path);
+                const target = getEntryToPage().get(args.path);
                 if (!target?.tsx)
                     return null;
                 const contents = target.tsx;

dist/functions/bunext-init.d.ts

@@ -3,7 +3,6 @@ import type { FileSystemRouter, Server } from "bun";
 import { type DirNames } from "../utils/grab-dir-names";
 import type { BuildContext } from "esbuild";
 import grabConstants from "../utils/grab-constants";
-import { type FSWatcher } from "fs";
 /**
  * # Declare Global Variables
  */
@@ -24,7 +23,7 @@ declare global {
         [k: string]: BundlerCTXMap;
     };
     var BUNEXT_BUNDLER_REBUILDS: 0;
-    var BUNEXT_PAGES_SRC_WATCHER: FSWatcher | undefined;
+    var BUNEXT_PAGES_SRC_WATCHER: any;
     var BUNEXT_CURRENT_VERSION: string | undefined;
     var BUNEXT_PAGE_FILES: PageFiles[];
     var BUNEXT_ROOT_FILE_UPDATED: boolean;
@@ -47,6 +46,13 @@ declare global {
     var BUNEXT_BUILD_FAILED: boolean;
     var BUNEXT_CONSTANTS: ReturnType<typeof grabConstants>;
     var BUNEXT_MAIN_CTX_BUILD_STARTS: number;
+    /**
+     * Resolves when the one-time dev startup build (hydration + SSR for all
+     * pages) has completed. The dev server starts listening before this
+     * resolves; page requests await it so they never render against
+     * half-built modules.
+     */
+    var BUNEXT_INITIAL_BUILD_PROMISE: Promise<void> | undefined;
 }
 type Params = {
     build_only?: boolean;

dist/functions/bunext-init.js

@@ -62,11 +62,21 @@ export default async function bunextInit(params) {
     }
     else if (is_dev) {
         log.build(`Building Modules ...`);
-        await allPagesESBuildContextBundler({
+        // Do NOT block on the full-site build: `Bun.serve` (or the start
-            post_build_fn: async () => {
+        // server) opens its port immediately and requests await
-                await serverPostBuildFn();
+        // BUNEXT_INITIAL_BUILD_PROMISE, so the site becomes reachable while
+        // the one-time compile still runs in the background.
+        const initial_build_promise = allPagesESBuildContextBundler({
+            post_build_fn: async (params) => {
+                await serverPostBuildFn(params);
             },
         });
+        global.BUNEXT_INITIAL_BUILD_PROMISE = initial_build_promise;
+        // Errors are logged (deduped) by the build pipeline itself; swallow
+        // the rejection here so it isn't an unhandled rejection.
+        initial_build_promise.catch(() => { });
+        // Start watching immediately so edits made during the initial build
+        // are not missed (rebuilds coalesce with the in-flight build).
         watcherEsbuildCTX();
     }
     else {

dist/functions/server/chokidar-watcher-esbuild-ctx.d.ts

@@ -1 +0,0 @@
-export default function chokadirWatcherEsbuildCTX(): Promise<void>;

dist/functions/server/chokidar-watcher-esbuild-ctx.js

@@ -1,133 +0,0 @@
-import chokidar from "chokidar";
-import path from "path";
-import { existsSync } from "fs";
-import grabDirNames from "../../utils/grab-dir-names";
-import fullRebuild from "./full-rebuild";
-import { AppData } from "../../data/app-data";
-import checkExcludedPatterns from "../../utils/check-excluded-patterns";
-import pagesSSRBundler from "../bundler/pages-ssr-bundler";
-import { log } from "../../utils/log";
-const { ROOT_DIR, BUNX_BUNDLER_ERROR_EXIT_FILE } = grabDirNames();
-export default async function chokadirWatcherEsbuildCTX() {
-    const watcher = chokidar.watch(ROOT_DIR, {
-        ignored: [
-            /(^|[\/\\])\../,
-            /node_modules/,
-            /public/,
-            /\.bunext/,
-            /\.git/,
-            /dist/,
-            /bun\.lockb/,
-            (path) => path.endsWith(AppData["BunextTmpFileExt"]),
-        ],
-        persistent: true,
-        ignoreInitial: true,
-        depth: 99,
-    });
-    const handleEvent = async (event, filePath) => {
-        let owns_recompile = false;
-        try {
-            const filename = path.relative(ROOT_DIR, filePath);
-            if (existsSync(BUNX_BUNDLER_ERROR_EXIT_FILE)) {
-                await fullRebuild();
-                return;
-            }
-            if (global.BUNEXT_BUNDLER_CTX_DISPOSED) {
-                await fullRebuild({ msg: `Restarting Bundler ...` });
-            }
-            if (global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED) {
-                await pagesSSRBundler().catch((error) => {
-                    log.error(`SSR Bundler Error: ${error}`);
-                });
-            }
-            if (filename.match(/\/styles$/) || filename === "styles") {
-                owns_recompile = true;
-                global.BUNEXT_RECOMPILING = true;
-                await Bun.sleep(1000);
-                await fullRebuild({
-                    msg: `Detected new \`styles\` directory. Rebuilding ...`,
-                });
-                return;
-            }
-            if (filename.match(/bunext.config\.ts/)) {
-                await fullRebuild({
-                    msg: `bunext.config.ts file changed. Rebuilding server ...`,
-                });
-                return;
-            }
-            const target_files_match = /\.(tsx?|jsx?|css)$/;
-            if (event === "change") {
-                if (filename.match(target_files_match)) {
-                    if (global.BUNEXT_RECOMPILING)
-                        return;
-                    owns_recompile = true;
-                    global.BUNEXT_RECOMPILING = true;
-                    if (filename.match(/.*\.server\.tsx?/)) {
-                        global.BUNEXT_IS_SERVER_COMPONENT = true;
-                    }
-                    if (global.BUNEXT_BUNDLER_CTX) {
-                        await global.BUNEXT_BUNDLER_CTX.rebuild();
-                    }
-                    if (filename.match(/(404|500)\.tsx?/)) {
-                        for (let i = global.BUNEXT_HMR_CONTROLLERS.length - 1; i >= 0; i--) {
-                            const controller = global.BUNEXT_HMR_CONTROLLERS[i];
-                            try {
-                                controller?.controller?.enqueue(`event: update\ndata: ${JSON.stringify({ reload: true })}\n\n`);
-                            }
-                            catch {
-                                global.BUNEXT_HMR_CONTROLLERS.splice(i, 1);
-                            }
-                        }
-                    }
-                }
-                return;
-            }
-            if (["add", "unlink", "addDir", "unlinkDir"].includes(event)) {
-                const is_file_of_interest = !!filename.match(target_files_match) ||
-                    event.includes("Dir");
-                if (!is_file_of_interest)
-                    return;
-                if (!filename.match(/^src\/pages\/|\.css$/) ||
-                    checkExcludedPatterns({ path: filename }) ||
-                    filename.includes(" ")) {
-                    return reloadWatcher();
-                }
-                if (global.BUNEXT_RECOMPILING)
-                    return;
-                owns_recompile = true;
-                const action = event.startsWith("add") ? "created" : "deleted";
-                const type = filename.match(/\.css$/)
-                    ? "Stylesheet"
-                    : event.includes("Dir")
-                        ? "Directory"
-                        : filename.match(/\/pages\/api\//)
-                            ? "API Route"
-                            : "Page";
-                await fullRebuild({
-                    msg: `${type} ${action}: ${filename}. Rebuilding ...`,
-                });
-            }
-        }
-        catch (error) {
-            log.error(`Watcher rebuild failed: ${error}`);
-        }
-        finally {
-            if (owns_recompile) {
-                global.BUNEXT_RECOMPILING = false;
-                global.BUNEXT_IS_SERVER_COMPONENT = false;
-            }
-        }
-    };
-    watcher
-        .on("add", (path) => handleEvent("add", path))
-        .on("change", (path) => handleEvent("change", path))
-        .on("unlink", (path) => handleEvent("unlink", path))
-        .on("addDir", (path) => handleEvent("addDir", path))
-        .on("unlinkDir", (path) => handleEvent("unlinkDir", path));
-}
-function reloadWatcher() {
-    if (global.BUNEXT_PAGES_SRC_WATCHER) {
-        global.BUNEXT_PAGES_SRC_WATCHER.close();
-        chokadirWatcherEsbuildCTX();
-    }
-}

dist/functions/server/cleanup-artifacts.d.ts

@@ -1,6 +1,14 @@
-import type { BundlerCTXMap } from "../../types";
 type Params = {
-    new_artifacts: BundlerCTXMap[];
+    paradigm: "hydration" | "ssr";
 };
-export default function cleanupArtifacts({ new_artifacts }: Params): Promise<void>;
+/**
+ * Deletes orphaned entry outputs left behind by previous rebuilds.
+ *
+ * After a rebuild the page/SSR artifact maps only reference the newest
+ * hashed entry files; every previously hashed entry for the same directory
+ * is provably unreferenced (generated HTML always uses the current map) and
+ * is removed. Chunks, non-hashed fallback module files and `map.json` are
+ * left untouched.
+ */
+export default function cleanupArtifacts({ paradigm }: Params): Promise<void>;
 export {};

dist/functions/server/cleanup-artifacts.js

@@ -2,32 +2,90 @@ import { log } from "../../utils/log";
 import path from "path";
 import grabDirNames from "../../utils/grab-dir-names";
 import { existsSync, readdirSync, statSync, unlinkSync } from "fs";
-const { ROOT_DIR, HYDRATION_DST_DIR_MAP_JSON_FILE_NAME } = grabDirNames();
+const { ROOT_DIR, HYDRATION_DST_DIR, BUNX_CWD_MODULE_CACHE_DIR } = grabDirNames();
-export default async function cleanupArtifacts({ new_artifacts }) {
+// esbuild's content hashes are 8-char base64-ish (e.g. `CMSI7VSQ`). Entry
+// outputs are `<dir>/<hash>.js` / `<dir>/<hash>.css`. Shared chunks are
+// `chunk-*.js` and MUST be kept: any current entry may still reference an
+// older chunk (esbuild reuses unchanged chunks across rebuilds), and
+// verifying references would require parsing every entry's imports.
+const ENTRY_HASH_FILE = /^[A-Za-z0-9]{8}\.(js|css)$/;
+/**
+ * Deletes orphaned entry outputs left behind by previous rebuilds.
+ *
+ * After a rebuild the page/SSR artifact maps only reference the newest
+ * hashed entry files; every previously hashed entry for the same directory
+ * is provably unreferenced (generated HTML always uses the current map) and
+ * is removed. Chunks, non-hashed fallback module files and `map.json` are
+ * left untouched.
+ */
+export default async function cleanupArtifacts({ paradigm }) {
+    const is_hydration = paradigm === "hydration";
+    const root_dir = is_hydration
+        ? HYDRATION_DST_DIR
+        : BUNX_CWD_MODULE_CACHE_DIR;
+    const map = is_hydration
+        ? global.BUNEXT_BUNDLER_CTX_MAP
+        : global.BUNEXT_SSR_BUNDLER_CTX_MAP;
+    if (!map || !existsSync(root_dir)) {
+        return;
+    }
     try {
-        for (let i = 0; i < new_artifacts.length; i++) {
+        const keep_by_dir = new Map();
-            const new_artifact = new_artifacts[i];
+        for (const entry of Object.values(map)) {
-            const artifact_public_dir = path.dirname(path.join(ROOT_DIR, new_artifact.path));
+            if (!entry?.path)
-            const dir_content = readdirSync(artifact_public_dir);
-            for (let d = 0; d < dir_content.length; d++) {
-                const dir_or_file = dir_content[d];
-                const full_path = path.join(artifact_public_dir, dir_or_file);
-                const file_or_path_stats = statSync(full_path);
-                if (file_or_path_stats.isDirectory() ||
-                    dir_or_file == HYDRATION_DST_DIR_MAP_JSON_FILE_NAME) {
                 continue;
+            const full_path = path.join(ROOT_DIR, entry.path);
+            const dir_path = path.dirname(full_path);
+            let keep = keep_by_dir.get(dir_path);
+            if (!keep) {
+                keep = new Set();
+                keep_by_dir.set(dir_path, keep);
             }
-                if (new_artifact.path.includes(dir_or_file) ||
+            keep.add(path.basename(full_path));
-                    new_artifact.css_path?.includes(dir_or_file)) {
+            if (entry.css_path) {
-                    continue;
+                keep.add(path.basename(entry.css_path));
-                }
-                if (existsSync(full_path)) {
-                    unlinkSync(full_path);
-                }
             }
         }
+        sweepDir(root_dir, keep_by_dir);
     }
     catch (error) {
-        log.error(error);
+        log.error(`Cleanup Artifacts Error: ${error?.message || error}`);
+    }
+}
+function sweepDir(dir_path, keep_by_dir) {
+    let entries;
+    try {
+        entries = readdirSync(dir_path);
+    }
+    catch (error) {
+        return;
+    }
+    for (const name of entries) {
+        const full_path = path.join(dir_path, name);
+        let is_dir = false;
+        try {
+            is_dir = statSync(full_path).isDirectory();
+        }
+        catch (error) {
+            continue;
+        }
+        if (is_dir) {
+            sweepDir(full_path, keep_by_dir);
+            continue;
+        }
+        if (!name.match(ENTRY_HASH_FILE)) {
+            continue;
+        }
+        if (name.startsWith("chunk-")) {
+            continue;
+        }
+        const keep = keep_by_dir.get(path.dirname(full_path));
+        if (keep?.has(name)) {
+            continue;
+        }
+        try {
+            unlinkSync(full_path);
+        }
+        catch (error) { }
     }
 }

dist/functions/server/full-rebuild.js

@@ -41,8 +41,8 @@ async function doFullRebuild(params) {
         }
         catch (error) { }
         await allPagesESBuildContextBundler({
-            post_build_fn: async () => {
+            post_build_fn: async (params) => {
-                await serverPostBuildFn();
+                await serverPostBuildFn(params);
             },
         });
     }

dist/functions/server/server-post-build-fn.d.ts

@@ -1,5 +1,14 @@
 type Params = {
     reload_all_controllers?: boolean;
+    /**
+     * Relative page paths whose client entry outputs changed in the last
+     * build. When provided with at least one entry, only controllers
+     * targeting those pages are re-rendered/re-pushed. When empty or
+     * omitted, every controller is refreshed (covers server-file-only
+     * changes, where hydration outputs are untouched but server props must
+     * still be re-fetched).
+     */
+    changed_pages?: string[];
 };
 export default function serverPostBuildFn(params?: Params): Promise<void>;
 export {};

dist/functions/server/server-post-build-fn.js

@@ -4,6 +4,9 @@ export default async function serverPostBuildFn(params) {
     if (!global.BUNEXT_HMR_CONTROLLERS?.[0] || !global.BUNEXT_BUNDLER_CTX_MAP) {
         return;
     }
+    const changed_set = params?.changed_pages && params.changed_pages.length > 0
+        ? new Set(params.changed_pages)
+        : undefined;
     const reload_payload = { reload: true };
     const reload_enqueue = `event: update\ndata: ${JSON.stringify(reload_payload)}\n\n`;
     for (let i = global.BUNEXT_HMR_CONTROLLERS.length - 1; i >= 0; i--) {
@@ -14,6 +17,10 @@ export default async function serverPostBuildFn(params) {
         if (!controller.target_map?.local_path) {
             continue;
         }
+        // Only touch controllers whose page actually changed.
+        if (changed_set && !changed_set.has(controller.target_map.local_path)) {
+            continue;
+        }
         if (params?.reload_all_controllers) {
             try {
                 controller.controller.enqueue(reload_enqueue);

dist/functions/server/watcher-esbuild-ctx.js

@@ -1,10 +1,12 @@
-import { watch, existsSync, statSync, glob } from "fs";
+import chokidar from "chokidar";
 import path from "path";
+import { existsSync } from "fs";
 import grabDirNames from "../../utils/grab-dir-names";
 import fullRebuild from "./full-rebuild";
 import { AppData } from "../../data/app-data";
 import checkExcludedPatterns from "../../utils/check-excluded-patterns";
-import pagesSSRBundler from "../bundler/pages-ssr-bundler";
+import allPagesESBuildContextBundler from "../bundler/all-pages-esbuild-context-bundler";
+import serverPostBuildFn from "./server-post-build-fn";
 import { log } from "../../utils/log";
 import { logBuildErrorsOnce } from "../../utils/build-error-log";
 const { ROOT_DIR, BUNX_BUNDLER_ERROR_EXIT_FILE } = grabDirNames();
@@ -21,7 +23,10 @@ export function restartWatcher() {
         return;
     if (Date.now() - last_watcher_restart < 1000)
         return;
+    try {
         global.BUNEXT_PAGES_SRC_WATCHER.close();
+    }
+    catch (error) { }
     global.BUNEXT_PAGES_SRC_WATCHER = undefined;
     last_watcher_restart = Date.now();
     watcherEsbuildCTX();
@@ -33,84 +38,67 @@ export function restartWatcher() {
 export function watcherRestartAvailable() {
     return Date.now() - last_watcher_restart > 6000;
 }
-export default async function watcherEsbuildCTX() {
+const TARGET_FILES_MATCH = /\.(tsx?|jsx?|css)$/;
-    const pages_src_watcher = watch(ROOT_DIR, {
+// Rebuild coalescing: editors emit bursts of events per save (change +
-        recursive: true,
+// atomic-swap noise), and edits can land while a rebuild is running.
-        persistent: true,
+// Events are debounced into a single runner; the runner loops until the
-    }, async (event, filename) => {
+// event queue drains, so a mid-build edit is never silently dropped.
-        let owns_recompile = false;
+const REBUILD_DEBOUNCE_MS = 200;
+let pending_structural = false;
+let pending_content_file = undefined;
+let debounce_timer = undefined;
+function scheduleRebuild() {
+    if (debounce_timer) {
+        clearTimeout(debounce_timer);
+    }
+    debounce_timer = setTimeout(async () => {
+        debounce_timer = undefined;
         try {
-            if (!filename)
+            await runRebuilds();
-                return;
+        }
-            const full_file_path = path.join(ROOT_DIR, filename);
+        catch (error) {
-            if (global.BUNEXT_CONFIG.exclude_watch_patterns) {
+            const msg = String(error?.message || error || "");
-                for (let i = 0; i < global.BUNEXT_CONFIG.exclude_watch_patterns.length; i++) {
+            if (!msg.startsWith("Build failed with")) {
-                    const watch_pattern = global.BUNEXT_CONFIG.exclude_watch_patterns[i];
+                logBuildErrorsOnce([{ text: `Watcher rebuild failed: ${msg}` }], (line) => log.error(line));
-                    if (watch_pattern instanceof RegExp) {
+            }
-                        const is_path_excluded = watch_pattern.test(filename);
+        }
-                        if (is_path_excluded) {
+        finally {
+            global.BUNEXT_RECOMPILING = false;
+            global.BUNEXT_IS_SERVER_COMPONENT = false;
+        }
+    }, REBUILD_DEBOUNCE_MS);
+}
+/**
+ * Processes the pending event batch. Structural changes go through the
+ * all-pages bundler (which re-creates esbuild contexts only when the entry
+ * set really changed, so atomic-swap saves resolve to incremental rebuilds).
+ * Content changes rebuild the hydration context incrementally; its artifact
+ * tracker then queues the single-flighted SSR rebuild and pushes HMR updates.
+ */
+async function runRebuilds() {
+    if (global.BUNEXT_RECOMPILING) {
         return;
     }
-                    }
-                    else {
-                        const excluded_path = path.resolve(ROOT_DIR, watch_pattern);
-                        if (excluded_path == full_file_path) {
-                            return;
-                        }
-                    }
-                }
-            }
-            if (existsSync(BUNX_BUNDLER_ERROR_EXIT_FILE)) {
-                await fullRebuild();
-                return;
-            }
-            if (filename.match(/^\.\w+/)) {
-                return;
-            }
-            if (global.BUNEXT_BUNDLER_CTX_DISPOSED) {
-                await fullRebuild({ msg: `Restarting Bundler ...` });
-                return;
-            }
-            if (global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED) {
-                await pagesSSRBundler().catch((error) => {
-                    log.error(`SSR Bundler Error: ${error}`);
-                });
-            }
-            if (filename.endsWith(AppData["BunextTmpFileExt"])) {
-                return;
-            }
-            const does_file_exist = existsSync(full_file_path);
-            const file_stat = does_file_exist
-                ? statSync(full_file_path)
-                : undefined;
-            if (full_file_path.match(/\/styles$/)) {
-                owns_recompile = true;
     global.BUNEXT_RECOMPILING = true;
-                await Bun.sleep(1000);
+    global.BUNEXT_IS_SERVER_COMPONENT = false;
-                await fullRebuild({
+    try {
-                    msg: `Detected new \`styles\` directory. Rebuilding ...`,
+        while (true) {
+            const structural = pending_structural;
+            const content_file = pending_content_file;
+            pending_structural = false;
+            pending_content_file = undefined;
+            if (!structural && !content_file) {
+                break;
+            }
+            if (structural) {
+                global.BUNEXT_ROUTER.reload();
+                await allPagesESBuildContextBundler({
+                    post_build_fn: async (params) => {
+                        await serverPostBuildFn(params);
+                    },
                 });
-                return;
-            }
-            const excluded_match = /node_modules\/|^public\/|^\.bunext\/|^\.git\/|^\.?dist\/|bun\.lockb$/;
-            if (filename.match(excluded_match))
-                return;
-            if (filename.match(/bunext.config\.ts/)) {
-                await fullRebuild({
-                    msg: `bunext.config.ts file changed. Rebuilding server ...`,
-                });
-                return;
-            }
-            const target_files_match = /\.(tsx?|jsx?|css)$/;
-            if (event !== "rename") {
-                if (filename.match(target_files_match)) {
-                    if (global.BUNEXT_RECOMPILING)
-                        return;
-                    owns_recompile = true;
-                    global.BUNEXT_RECOMPILING = true;
-                    if (filename.match(/.*\.server\.tsx?/)) {
-                        global.BUNEXT_IS_SERVER_COMPONENT = true;
             }
+            else if (content_file) {
                 if (global.BUNEXT_BUNDLER_CTX &&
                     !global.BUNEXT_BUNDLER_CTX_DISPOSED) {
                     await global.BUNEXT_BUNDLER_CTX.rebuild();
@@ -119,9 +107,9 @@ export default async function watcherEsbuildCTX() {
                     await fullRebuild({
                         msg: `Restarting Bundler ...`,
                     });
-                        return;
+                    break;
                 }
-                    if (filename.match(/(404|500)\.tsx?/)) {
+                if (content_file.match(/(404|500)\.tsx?$/)) {
                     for (let i = global.BUNEXT_HMR_CONTROLLERS.length - 1; i >= 0; i--) {
                         const controller = global.BUNEXT_HMR_CONTROLLERS[i];
                         try {
@@ -133,51 +121,137 @@ export default async function watcherEsbuildCTX() {
                     }
                 }
             }
-                return;
-            }
-            const is_file_of_interest = Boolean(filename.match(target_files_match)) ||
-                file_stat?.isDirectory();
-            if (!is_file_of_interest) {
-                return;
-            }
-            if (!filename.match(/^src\/pages\/|\.css$/))
-                return reloadWatcher();
-            if (checkExcludedPatterns({ path: filename }))
-                return reloadWatcher();
-            if (filename.match(/ /))
-                return reloadWatcher();
-            if (global.BUNEXT_RECOMPILING)
-                return;
-            owns_recompile = true;
-            const action = does_file_exist ? "created" : "deleted";
-            const type = filename.match(/\.css$/)
-                ? "Sylesheet"
-                : file_stat?.isDirectory()
-                    ? "Directory"
-                    : filename.match(/\/pages\/api\//)
-                        ? "API Route"
-                        : "Page";
-            await fullRebuild({
-                msg: `${type} ${action}: ${filename}. Rebuilding ...`,
-            });
-        }
-        catch (error) {
-            // A "Build failed with N errors" rejection is the same
-            // failure the tracker's onEnd already reported (deduped).
-            const msg = String(error?.message || error || "");
-            if (!msg.startsWith("Build failed with")) {
-                logBuildErrorsOnce([{ text: `Watcher rebuild failed: ${msg}` }], (line) => log.error(line));
         }
     }
     finally {
-            if (owns_recompile) {
         global.BUNEXT_RECOMPILING = false;
         global.BUNEXT_IS_SERVER_COMPONENT = false;
     }
 }
+function isPathExcluded(filename, full_file_path) {
+    const user_patterns = global.BUNEXT_CONFIG?.exclude_watch_patterns;
+    if (!user_patterns)
+        return false;
+    for (let i = 0; i < user_patterns.length; i++) {
+        const watch_pattern = user_patterns[i];
+        if (watch_pattern instanceof RegExp) {
+            if (watch_pattern.test(filename))
+                return true;
+        }
+        else {
+            const excluded_path = path.resolve(ROOT_DIR, watch_pattern);
+            if (excluded_path == full_file_path)
+                return true;
+        }
+    }
+    return false;
+}
+// Heavy directories are filtered at the watcher level so inotify doesn't
+// install watches (and deliver events) for trees the bundler never reads.
+function buildIgnoredPatterns() {
+    const ignored = [
+        /(^|[\/\\])\../,
+        /(^|[\/\\])node_modules([\/\\]|$)/,
+        /(^|[\/\\])public([\/\\]|$)/,
+        /(^|[\/\\])\.bunext([\/\\]|$)/,
+        /(^|[\/\\])\.git([\/\\]|$)/,
+        /(^|[\/\\])dist([\/\\]|$)/,
+        /bun\.lockb$/,
+        (p) => p.endsWith(AppData["BunextTmpFileExt"]),
+    ];
+    const user_patterns = global.BUNEXT_CONFIG?.exclude_watch_patterns;
+    if (user_patterns) {
+        for (let i = 0; i < user_patterns.length; i++) {
+            const pattern = user_patterns[i];
+            if (pattern instanceof RegExp) {
+                ignored.push((p) => pattern.test(path.relative(ROOT_DIR, p)));
+            }
+            else {
+                const excluded_path = path.resolve(ROOT_DIR, pattern);
+                ignored.push((p) => p === excluded_path);
+            }
+        }
+    }
+    return ignored;
+}
+export default async function watcherEsbuildCTX() {
+    const pages_src_watcher = chokidar.watch(ROOT_DIR, {
+        ignored: buildIgnoredPatterns(),
+        persistent: true,
+        ignoreInitial: true,
     });
+    watcherHandlers(pages_src_watcher, (event, filePath) => handleEvent(event, filePath));
     global.BUNEXT_PAGES_SRC_WATCHER = pages_src_watcher;
 }
-function reloadWatcher() {
+function handleEvent(event, filePath) {
-    restartWatcher();
+    try {
+        const filename = path.relative(ROOT_DIR, filePath);
+        const full_file_path = filePath;
+        if (isPathExcluded(filename, full_file_path)) {
+            return;
+        }
+        if (existsSync(BUNX_BUNDLER_ERROR_EXIT_FILE)) {
+            fullRebuild();
+            return;
+        }
+        if (filename.endsWith(AppData["BunextTmpFileExt"])) {
+            return;
+        }
+        if (full_file_path.match(/\/styles$/)) {
+            pending_structural = false;
+            pending_content_file = undefined;
+            if (debounce_timer)
+                clearTimeout(debounce_timer);
+            setTimeout(() => {
+                fullRebuild({
+                    msg: `Detected new \`styles\` directory. Rebuilding ...`,
+                });
+            }, 1000);
+            return;
+        }
+        if (filename.match(/bunext\.config\.ts/)) {
+            pending_structural = false;
+            pending_content_file = undefined;
+            if (debounce_timer)
+                clearTimeout(debounce_timer);
+            fullRebuild({
+                msg: `bunext.config.ts file changed. Rebuilding server ...`,
+            });
+            return;
+        }
+        if (event === "change") {
+            if (filename.match(TARGET_FILES_MATCH)) {
+                pending_content_file = full_file_path;
+                scheduleRebuild();
+            }
+            return;
+        }
+        // add / unlink / addDir / unlinkDir
+        const is_dir_event = event === "addDir" || event === "unlinkDir";
+        const is_file_of_interest = Boolean(filename.match(TARGET_FILES_MATCH)) || is_dir_event;
+        if (!is_file_of_interest) {
+            return;
+        }
+        // Only page routes and stylesheets are structural; anything else
+        // (e.g. a component being added) is covered by the next content
+        // rebuild and needs no context recreation.
+        if (!filename.match(/^src\/pages\/|\.css$/) ||
+            checkExcludedPatterns({ path: filename }) ||
+            filename.match(/ /)) {
+            return;
+        }
+        pending_structural = true;
+        scheduleRebuild();
+    }
+    catch (error) {
+        logBuildErrorsOnce([{ text: `Watcher error: ${error?.message || error}` }], (line) => log.error(line));
+    }
+}
+function watcherHandlers(watcher, handleEvent) {
+    watcher
+        .on("add", (p) => handleEvent("add", p))
+        .on("change", (p) => handleEvent("change", p))
+        .on("unlink", (p) => handleEvent("unlink", p))
+        .on("addDir", (p) => handleEvent("addDir", p))
+        .on("unlinkDir", (p) => handleEvent("unlinkDir", p));
 }

dist/functions/server/web-pages/handle-web-pages.js

@@ -22,6 +22,15 @@ export default async function handleWebPages({ req, }) {
                 return new Response(existing_cache, res_opts);
             }
         }
+        // The dev server port opens before the one-time startup build
+        // finishes. First page render waits for it so we never serve HTML
+        // against half-built hydration/SSR modules.
+        if (is_dev && global.BUNEXT_INITIAL_BUILD_PROMISE) {
+            try {
+                await global.BUNEXT_INITIAL_BUILD_PROMISE;
+            }
+            catch (error) { }
+        }
         const componentRes = await grabPageComponent({
             req,
         });

src/commands/build/index.ts

@@ -3,7 +3,6 @@ import { log } from "../../utils/log";
 import grabDirNames from "../../utils/grab-dir-names";
 import { rmSync, writeFileSync } from "fs";
 import bunextInit from "../../functions/bunext-init";
-import pagesSSRBundler from "../../functions/bundler/pages-ssr-bundler";
 import type { BuildDataType } from "../../types";
 import { v4 } from "uuid";
 
@@ -32,7 +31,6 @@ export default function () {
             global.BUNEXT_SKIPPED_BROWSER_MODULES = new Set<string>();
 
             await bunextInit({ build_only: true });
-            // await pagesSSRBundler();
 
             // A failed bundle must fail the command: CI and scripts rely on
             // the exit code instead of grepping logs.

src/functions/bundler/all-pages-esbuild-context-bundler.ts

@@ -12,19 +12,36 @@ import {
     logBuildErrorsOnce,
 } from "../../utils/build-error-log";
 import { log } from "../../utils/log";
+import grabRootFilePath from "../server/web-pages/grab-root-file-path";
 
 const { HYDRATION_DST_DIR, BUNX_HYDRATION_SRC_DIR } = grabDirNames();
 
 type Params = {
     post_build_fn?: (params: {
         artifacts: BundlerCTXMap[];
+        changed_pages?: string[];
     }) => Promise<void> | void;
     build_only?: boolean;
     start?: boolean;
 };
 
+type HydrationVirtualEntry = PageFiles & { tsx: string };
+
+// Snapshot of the entry key set + root file presence of the last build.
+// When it differs from the freshly computed set, the esbuild context must
+// be recreated (entry points are fixed at context creation).
+let last_entry_keys: string[] | undefined = undefined;
+let last_root_file_path: string | undefined = undefined;
+
+function arraysEqual(a: string[], b: string[]): boolean {
+    if (a.length !== b.length) return false;
+    for (let i = 0; i < a.length; i++) {
+        if (a[i] !== b[i]) return false;
+    }
+    return true;
+}
+
 export default async function allPagesESBuildContextBundler(params?: Params) {
-    const _t0 = Date.now();
     try {
         const pages = grabAllPages({ exclude_api: true });
 
@@ -32,7 +49,7 @@ export default async function allPagesESBuildContextBundler(params?: Params) {
 
         const dev = isDevelopment();
 
-        const entryToPage = new Map<string, PageFiles & { tsx: string }>();
+        const entryToPage = new Map<string, HydrationVirtualEntry>();
 
         for (const page of pages) {
             const tsx = await grabClientHydrationScript({
@@ -48,7 +65,6 @@ export default async function allPagesESBuildContextBundler(params?: Params) {
                 `${page.url_path}.tsx`,
             );
 
-            // await Bun.write(entryFile, txt, { createPath: true });
             entryToPage.set(entryFile, { ...page, tsx });
         }
 
@@ -56,9 +72,21 @@ export default async function allPagesESBuildContextBundler(params?: Params) {
             (e) => `hydration-virtual:${e}`,
         );
 
-        // This is a brand-new context: wipe the previous context's failure
+        const entry_keys = [...entryToPage.keys()].sort();
-        // history so the "2 failed starts => dispose" guard starts fresh.
+        const { root_file_path } = grabRootFilePath();
-        global.BUNEXT_MAIN_CTX_BUILD_STARTS = 0;
+
+        const structure_changed =
+            !global.BUNEXT_BUNDLER_CTX ||
+            global.BUNEXT_BUNDLER_CTX_DISPOSED ||
+            !last_entry_keys ||
+            !arraysEqual(last_entry_keys, entry_keys) ||
+            last_root_file_path !== root_file_path;
+
+        if (structure_changed) {
+            try {
+                await global.BUNEXT_BUNDLER_CTX?.dispose();
+            } catch (error) {}
+            global.BUNEXT_BUNDLER_CTX = undefined;
 
             global.BUNEXT_BUNDLER_CTX = await esbuild.context({
                 entryPoints,
@@ -103,7 +131,11 @@ export default async function allPagesESBuildContextBundler(params?: Params) {
                 logLevel: "silent",
             });
 
-        await global.BUNEXT_BUNDLER_CTX.rebuild();
+            last_entry_keys = entry_keys;
+            last_root_file_path = root_file_path;
+        }
+
+        await global.BUNEXT_BUNDLER_CTX!.rebuild();
     } catch (error: any) {
         global.BUNEXT_BUILD_FAILED = true;
 

src/functions/bundler/pages-ssr-bundler.ts

@@ -1,136 +0,0 @@
-import * as esbuild from "esbuild";
-import grabAllPages from "../../utils/grab-all-pages";
-import grabDirNames from "../../utils/grab-dir-names";
-import isDevelopment from "../../utils/is-development";
-import tailwindEsbuildPlugin from "../server/web-pages/tailwind-esbuild-plugin";
-import type { PageFiles } from "../../types";
-import grabPageReactComponentString from "../server/web-pages/grab-page-react-component-string";
-import grabRootFilePath from "../server/web-pages/grab-root-file-path";
-import ssrVirtualFilesPlugin from "./plugins/ssr-virtual-files-plugin";
-import ssrCTXArtifactTracker from "./plugins/ssr-ctx-artifact-tracker";
-import { writeFileSync } from "fs";
-import path from "path";
-import { log } from "../../utils/log";
-import {
-    logBuildErrorsOnce,
-} from "../../utils/build-error-log";
-
-const { BUNX_CWD_MODULE_CACHE_DIR, BUNX_TMP_DIR } = grabDirNames();
-
-type Params = {
-    post_build_fn?: (params: { artifacts: any[] }) => Promise<void> | void;
-};
-
-export default async function pagesSSRBundler(params?: Params) {
-    const pages = grabAllPages({
-        include_server: true,
-    });
-    const dev = isDevelopment();
-    const config = global.BUNEXT_CONFIG;
-
-    try {
-        writeFileSync(
-            path.join(BUNX_TMP_DIR, "ssr-pages.json"),
-            JSON.stringify(pages, null, 4),
-        );
-    } catch (error) {}
-
-    const entryToPage = new Map<string, PageFiles & { tsx: string }>();
-    const { root_file_path } = grabRootFilePath();
-
-    for (const page of pages) {
-        if (
-            page.local_path.match(/\/pages\/api\//) ||
-            page.local_path.match(/\.server\.tsx?$/)
-        ) {
-            const ts = await Bun.file(page.local_path).text();
-            if (
-                ts.match(
-                    /(export default)|(export \w+ handler)|(export \w+ server)/,
-                )
-            ) {
-                entryToPage.set(page.local_path, { ...page, tsx: ts });
-            }
-            continue;
-        }
-
-        const tsx = grabPageReactComponentString({
-            file_path: page.local_path,
-            root_file_path,
-        });
-
-        if (!tsx) continue;
-        if (!tsx.match(/export default/)) continue;
-
-        entryToPage.set(page.local_path, { ...page, tsx });
-    }
-
-    const entryPoints = [...entryToPage.keys()].map((e) => `ssr-virtual:${e}`);
-
-    try {
-        writeFileSync(
-            path.join(BUNX_TMP_DIR, "ssr-entry-to-page.json"),
-            JSON.stringify(Object(entryToPage), null, 4),
-        );
-        writeFileSync(
-            path.join(BUNX_TMP_DIR, "ssr-entrypoints.json"),
-            JSON.stringify(entryPoints, null, 4),
-        );
-    } catch (error) {}
-
-    try {
-        await esbuild.build({
-            entryPoints,
-            outdir: BUNX_CWD_MODULE_CACHE_DIR,
-            bundle: true,
-            minify: !dev,
-            format: "esm",
-            target: "esnext",
-            platform: "node",
-            define: {
-                "process.env.NODE_ENV": JSON.stringify(
-                    dev ? "development" : "production",
-                ),
-            },
-            entryNames: "[dir]/[hash]",
-            metafile: true,
-            plugins: [
-                tailwindEsbuildPlugin,
-                ssrVirtualFilesPlugin({
-                    entryToPage,
-                }),
-                ssrCTXArtifactTracker({
-                    entryToPage,
-                    post_build_fn: params?.post_build_fn,
-                }),
-            ],
-            jsx: "automatic",
-            external: [
-                "react",
-                "react-dom",
-                "react/jsx-runtime",
-                "react/jsx-dev-runtime",
-                "bun:*",
-                "bun",
-                "sqlite-vec",
-                "better-sqlite3",
-                ...(config.ssr_compiler_excludes || []),
-            ],
-            splitting: true,
-            logLevel: "silent",
-        });
-    } catch (error: any) {
-        global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED = true;
-        global.BUNEXT_BUILD_FAILED = true;
-        logBuildErrorsOnce(
-            [
-                {
-                    text: `SSR Bundler Error: ${
-                        error?.message || String(error)
-                    }`,
-                },
-            ],
-            (line) => log.error(line),
-        );
-    }
-}

src/functions/bundler/pages-ssr-context-bundler.ts

@@ -8,29 +8,77 @@ import grabPageReactComponentString from "../server/web-pages/grab-page-react-co
 import grabRootFilePath from "../server/web-pages/grab-root-file-path";
 import ssrVirtualFilesPlugin from "./plugins/ssr-virtual-files-plugin";
 import ssrCTXArtifactTracker from "./plugins/ssr-ctx-artifact-tracker";
+import cleanupArtifacts from "../server/cleanup-artifacts";
+import { writeFileSync } from "fs";
+import path from "path";
+import { log } from "../../utils/log";
+import {
+    logBuildErrorsOnce,
+} from "../../utils/build-error-log";
 
-const { BUNX_CWD_MODULE_CACHE_DIR } = grabDirNames();
+const { BUNX_CWD_MODULE_CACHE_DIR, BUNX_TMP_DIR } = grabDirNames();
 
-type Params = {
+type SSRVirtualEntry = PageFiles & { tsx: string };
-    post_build_fn?: (params: { artifacts: any[] }) => Promise<void> | void;
+
+// Current virtual entry contents. The SSR virtual plugin resolves its
+// onLoad contents lazily from this map on every rebuild, so edits to
+// `.server.ts`/api files (whose entries mirror their raw file content) are
+// picked up without recreating the esbuild context.
+let current_entry_map = new Map<string, SSRVirtualEntry>();
+// Entry key set + root file presence of the last *successful* build. When
+// this differs from the freshly computed set, the context must be
+// recreated (esbuild cannot add/remove entry points on a live context).
+let last_entry_keys: string[] | undefined = undefined;
+let last_root_file_path: string | undefined = undefined;
+
+let rebuild_in_flight: Promise<void> | undefined;
+
+type RebuildParams = {
+    /**
+     * Force a context recreation even when the entry set is unchanged.
+     * Used by `fullRebuild` after it disposed the contexts.
+     */
+    force?: boolean;
 };
 
-export default async function pagesSSRContextBundler(params?: Params) {
+function arraysEqual(a: string[], b: string[]): boolean {
-    const pages = grabAllPages();
+    if (a.length !== b.length) return false;
-    const dev = isDevelopment();
+    for (let i = 0; i < a.length; i++) {
-
+        if (a[i] !== b[i]) return false;
-    if (global.BUNEXT_SSR_BUNDLER_CTX) {
+    }
-        await global.BUNEXT_SSR_BUNDLER_CTX.dispose();
+    return true;
-        global.BUNEXT_SSR_BUNDLER_CTX = undefined;
 }
 
-    const entryToPage = new Map<string, PageFiles & { tsx: string }>();
+async function computeEntryToPage(): Promise<{
+    entryToPage: Map<string, SSRVirtualEntry>;
+    root_file_path: string | undefined;
+}> {
+    const pages = grabAllPages({
+        include_server: true,
+    });
     const { root_file_path } = grabRootFilePath();
+    const entryToPage = new Map<string, SSRVirtualEntry>();
+
+    try {
+        writeFileSync(
+            path.join(BUNX_TMP_DIR, "ssr-pages.json"),
+            JSON.stringify(pages, null, 4),
+        );
+    } catch (error) {}
 
     for (const page of pages) {
-        if (page.local_path.match(/\/pages\/api\//)) {
+        if (
+            page.local_path.match(/\/pages\/api\//) ||
+            page.local_path.match(/\.server\.tsx?$/)
+        ) {
             const ts = await Bun.file(page.local_path).text();
+            if (
+                ts.match(
+                    /(export default)|(export \w+ handler)|(export \w+ server)/,
+                )
+            ) {
                 entryToPage.set(page.local_path, { ...page, tsx: ts });
+            }
             continue;
         }
 
@@ -40,11 +88,86 @@ export default async function pagesSSRContextBundler(params?: Params) {
         });
 
         if (!tsx) continue;
+        if (!tsx.match(/export default/)) continue;
 
         entryToPage.set(page.local_path, { ...page, tsx });
     }
 
-    const entryPoints = [...entryToPage.keys()].map((e) => `ssr-virtual:${e}`);
+    return { entryToPage, root_file_path };
+}
+
+/**
+ * Single-flight SSR rebuild. Concurrent callers (each successful hydration
+ * rebuild triggers this, plus watcher/structural paths) join the in-flight
+ * rebuild instead of spawning overlapping esbuild builds.
+ *
+ * A fresh content change that lands while a rebuild is in flight is picked
+ * up by the next hydration rebuild cycle (each watcher event re-runs the
+ * hydration context rebuild, which re-enters this queue).
+ */
+export default async function enqueueSSRRebuild(params?: RebuildParams) {
+    if (rebuild_in_flight) {
+        return rebuild_in_flight;
+    }
+
+    const run = doSSRRebuild(params).finally(() => {
+        if (rebuild_in_flight === run) {
+            rebuild_in_flight = undefined;
+        }
+    });
+
+    rebuild_in_flight = run;
+    return run;
+}
+
+async function doSSRRebuild(params?: RebuildParams) {
+    const force = Boolean(params?.force);
+    const dev = isDevelopment();
+    const config = global.BUNEXT_CONFIG;
+
+    try {
+        const { entryToPage, root_file_path } = await computeEntryToPage();
+        const entry_keys = [...entryToPage.keys()].sort();
+
+        if (entry_keys.length === 0) {
+            current_entry_map = entryToPage;
+            last_entry_keys = entry_keys;
+            last_root_file_path = root_file_path;
+            return;
+        }
+
+        // Refresh the virtual contents BEFORE rebuilding so the plugin's
+        // onLoad sees the latest `.server.ts`/api contents.
+        current_entry_map = entryToPage;
+
+        const entryPoints = [...entryToPage.keys()].map(
+            (e) => `ssr-virtual:${e}`,
+        );
+
+        try {
+            writeFileSync(
+                path.join(BUNX_TMP_DIR, "ssr-entry-to-page.json"),
+                JSON.stringify(Object(entryToPage), null, 4),
+            );
+            writeFileSync(
+                path.join(BUNX_TMP_DIR, "ssr-entrypoints.json"),
+                JSON.stringify(entryPoints, null, 4),
+            );
+        } catch (error) {}
+
+        const structure_changed =
+            !global.BUNEXT_SSR_BUNDLER_CTX ||
+            global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED ||
+            force ||
+            !last_entry_keys ||
+            !arraysEqual(last_entry_keys, entry_keys) ||
+            last_root_file_path !== root_file_path;
+
+        if (structure_changed) {
+            try {
+                await global.BUNEXT_SSR_BUNDLER_CTX?.dispose();
+            } catch (error) {}
+            global.BUNEXT_SSR_BUNDLER_CTX = undefined;
 
             global.BUNEXT_SSR_BUNDLER_CTX = await esbuild.context({
                 entryPoints,
@@ -64,11 +187,10 @@ export default async function pagesSSRContextBundler(params?: Params) {
                 plugins: [
                     tailwindEsbuildPlugin,
                     ssrVirtualFilesPlugin({
-                entryToPage,
+                        getEntryToPage: () => current_entry_map,
                     }),
                     ssrCTXArtifactTracker({
                         entryToPage,
-                post_build_fn: params?.post_build_fn,
                     }),
                 ],
                 jsx: "automatic",
@@ -78,9 +200,43 @@ export default async function pagesSSRContextBundler(params?: Params) {
                     "react/jsx-runtime",
                     "react/jsx-dev-runtime",
                     "bun:*",
+                    "bun",
+                    "sqlite-vec",
+                    "better-sqlite3",
+                    ...(config.ssr_compiler_excludes || []),
                 ],
-        // logLevel: "silent",
+                splitting: true,
+                logLevel: "silent",
             });
+        }
 
-    await global.BUNEXT_SSR_BUNDLER_CTX.rebuild();
+        await global.BUNEXT_SSR_BUNDLER_CTX!.rebuild();
+
+        // Only record the entry set after a successful build so a failed
+        // build retries with a fresh context next time.
+        last_entry_keys = entry_keys;
+        last_root_file_path = root_file_path;
+        global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED = false;
+        global.BUNEXT_BUILD_FAILED = false;
+
+        await cleanupArtifacts({ paradigm: "ssr" });
+    } catch (error: any) {
+        global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED = true;
+        global.BUNEXT_BUILD_FAILED = true;
+
+        // esbuild errors are reported (deduped) by the ssr artifact tracker's
+        // onEnd; only re-log unexpected failures.
+        if (!String(error?.message || "").startsWith("Build failed with")) {
+            logBuildErrorsOnce(
+                [
+                    {
+                        text: `SSR Bundler Error: ${
+                            error?.message || String(error)
+                        }`,
+                    },
+                ],
+                (line) => log.error(line),
+            );
+        }
+    }
 }

src/functions/bundler/plugins/esbuild-ctx-artifact-tracker.ts

@@ -2,25 +2,23 @@ import { type Plugin } from "esbuild";
 import type { PageFiles } from "../../../types";
 import { log } from "../../../utils/log";
 import grabArtifactsFromBundledResults from "../grab-artifacts-from-bundled-result";
-import buildOnstartErrorHandler from "../build-on-start-error-handler";
 import _ from "lodash";
-import pagesSSRBundler from "../pages-ssr-bundler";
+import enqueueSSRRebuild from "../pages-ssr-context-bundler";
 import grabDirNames from "../../../utils/grab-dir-names";
 import {
     logBuildErrorsOnce,
     resetBuildErrorLog,
 } from "../../../utils/build-error-log";
-import { cpSync, existsSync, mkdirSync, rmSync, writeFileSync } from "fs";
+import { cpSync, existsSync, mkdirSync, rmSync } from "fs";
 import fullRebuild from "../../server/full-rebuild";
 import path from "path";
 import cleanupLogsDirs from "../../cleanup-logs-dir";
 import grabRelativePath from "../../../utils/grab-relative-path";
+import cleanupArtifacts from "../../server/cleanup-artifacts";
 
-const { BUNX_BUNDLER_ERROR_EXIT_FILE, BUNX_ERROR_LOGS_DIR, ROOT_DIR } =
+const { BUNX_BUNDLER_ERROR_EXIT_FILE, BUNX_ERROR_LOGS_DIR } = grabDirNames();
-    grabDirNames();
 
 let build_start = 0;
-const MAX_BUILD_STARTS = 2;
 
 type Params = {
     entryToPage: Map<
@@ -29,7 +27,10 @@ type Params = {
             tsx: string;
         }
     >;
-    post_build_fn?: (params: { artifacts: any[] }) => Promise<void> | void;
+    post_build_fn?: (params: {
+        artifacts: any[];
+        changed_pages?: string[];
+    }) => Promise<void> | void;
     build_only?: boolean;
 };
 
@@ -42,19 +43,7 @@ export default function esbuildCTXArtifactTracker({
         name: "artifact-tracker",
         setup(build) {
             build.onStart(async () => {
-                global.BUNEXT_MAIN_CTX_BUILD_STARTS++;
                 build_start = performance.now();
-
-                const does_error_file_exist = existsSync(
-                    BUNX_BUNDLER_ERROR_EXIT_FILE,
-                );
-
-                if (
-                    global.BUNEXT_MAIN_CTX_BUILD_STARTS >= MAX_BUILD_STARTS &&
-                    !does_error_file_exist
-                ) {
-                    await buildOnstartErrorHandler();
-                }
             });
 
             build.onEnd(async (result) => {
@@ -92,6 +81,12 @@ export default function esbuildCTXArtifactTracker({
                     entryToPage,
                 });
 
+                // Pages whose entry output hash changed since the previous
+                // build. With `splitting`, a change to any shared chunk also
+                // re-hashes every page entry that imports it, so this set
+                // covers all pages whose client graph actually changed.
+                const changed_pages: string[] = [];
+
                 if (artifacts?.[0] && artifacts.length > 0) {
                     for (let i = 0; i < artifacts.length; i++) {
                         const artifact = artifacts[i];
@@ -104,13 +99,22 @@ export default function esbuildCTXArtifactTracker({
                                 artifact.local_path,
                             );
 
+                            const prior =
+                                global.BUNEXT_BUNDLER_CTX_MAP[relative_path];
+
+                            if (
+                                !prior?.path ||
+                                prior.path !== artifact.path ||
+                                prior.css_path !== artifact.css_path
+                            ) {
+                                changed_pages.push(relative_path);
+                            }
+
                             global.BUNEXT_BUNDLER_CTX_MAP[relative_path] =
-                                _.merge(
+                                _.merge(prior, {
-                                    global.BUNEXT_BUNDLER_CTX_MAP[
+                                    ...artifact,
-                                        relative_path
+                                    local_path: relative_path,
-                                    ],
+                                });
-                                    { ...artifact, local_path: relative_path },
-                                );
                         }
                     }
                 }
@@ -129,17 +133,19 @@ export default function esbuildCTXArtifactTracker({
                 }
 
                 global.BUNEXT_BUILD_FAILED = false;
-                global.BUNEXT_MAIN_CTX_BUILD_STARTS = 0;
                 global.BUNEXT_BUNDLER_CTX_DISPOSED = false;
 
                 const does_error_file_exist = existsSync(
                     BUNX_BUNDLER_ERROR_EXIT_FILE,
                 );
 
-                // SSR must finish before HMR so server props are fresh
+                // SSR must finish before HMR so server props are fresh.
+                // The rebuild is single-flighted: concurrent hydration
+                // rebuilds join the in-flight SSR rebuild instead of
+                // starting overlapping ones.
                 if (build_only) {
                     try {
-                        await pagesSSRBundler();
+                        await enqueueSSRRebuild();
                     } catch (error) {
                         log.error(`SSR Bundler Error: ${error}`);
                     }
@@ -154,20 +160,26 @@ export default function esbuildCTXArtifactTracker({
                     await fullRebuild();
                 } else {
                     try {
-                        await pagesSSRBundler();
+                        await enqueueSSRRebuild();
                     } catch (error) {
                         log.error(`SSR Bundler Error: ${error}`);
                     }
 
                     if (artifacts?.[0] && artifacts.length > 0) {
                         try {
-                            await post_build_fn?.({ artifacts });
+                            await post_build_fn?.({
+                                artifacts,
+                                changed_pages,
+                            });
                         } catch (error) {
                             log.error(`Post-build Error: ${error}`);
                         }
                     }
                 }
 
+                // Prune orphaned entry outputs from previous rebuilds.
+                await cleanupArtifacts({ paradigm: "hydration" });
+
                 global.BUNEXT_RECOMPILING = false;
                 global.BUNEXT_IS_SERVER_COMPONENT = false;
             });

src/functions/bundler/plugins/ssr-ctx-artifact-tracker.ts

@@ -12,10 +12,8 @@ import {
 import { log } from "../../../utils/log";
 
 let build_start = 0;
-let build_starts = 0;
-const MAX_BUILD_STARTS = 2;
 
-const { BUNX_TMP_DIR, ROOT_DIR } = grabDirNames();
+const { BUNX_TMP_DIR } = grabDirNames();
 
 type Params = {
     entryToPage: Map<
@@ -24,35 +22,20 @@ type Params = {
             tsx: string;
         }
     >;
-    post_build_fn?: (params: { artifacts: any[] }) => Promise<void> | void;
 };
 
-export default function ssrCTXArtifactTracker({
+export default function ssrCTXArtifactTracker({ entryToPage }: Params) {
-    entryToPage,
-    post_build_fn,
-}: Params) {
     const artifactTracker: Plugin = {
         name: "ssr-artifact-tracker",
         setup(build) {
             build.onStart(async () => {
-                build_starts++;
                 build_start = performance.now();
-                if (build_starts == MAX_BUILD_STARTS) {
-                    global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED = true;
-                    await global.BUNEXT_SSR_BUNDLER_CTX?.dispose();
-                    global.BUNEXT_SSR_BUNDLER_CTX = undefined;
-                }
             });
 
             build.onEnd(async (result) => {
                 if (result.errors.length > 0) {
                     global.BUNEXT_BUILD_FAILED = true;
                     global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED = true;
-                    try {
-                        await global.BUNEXT_SSR_BUNDLER_CTX?.dispose();
-                    } catch {}
-                    global.BUNEXT_SSR_BUNDLER_CTX = undefined;
-                    build_starts = 0;
                     logBuildErrorsOnce(result.errors, (line) =>
                         log.error(`SSR Build error: ${line}`),
                     );
@@ -83,13 +66,6 @@ export default function ssrCTXArtifactTracker({
                             };
                         }
                     }
-
-                    // post_build_fn?.({ artifacts });
-
-                    // const elapsed = (performance.now() - build_start).toFixed(
-                    //     0,
-                    // );
-                    // log.success(`SSR [Built] in ${elapsed}ms`);
                 }
 
                 try {
@@ -103,6 +79,9 @@ export default function ssrCTXArtifactTracker({
                     );
                 } catch (error) {}
 
+                // const elapsed = (performance.now() - build_start).toFixed(0);
+                // log.success(`SSR [Built] in ${elapsed}ms`);
+
                 global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED = false;
                 global.BUNEXT_BUILD_FAILED = false;
                 resetBuildErrorLog();

src/functions/bundler/plugins/ssr-virtual-files-plugin.ts

@@ -1,18 +1,20 @@
 import type { Plugin } from "esbuild";
 import path from "path";
 import type { PageFiles } from "../../../types";
-import { log } from "../../../utils/log";
+
+type SSRVirtualEntry = PageFiles & { tsx: string };
 
 type Params = {
-    entryToPage: Map<
+    /**
-        string,
+     * Lazily-resolved current virtual entry contents. The map is refreshed
-        PageFiles & {
+     * before every rebuild so edits to `.server.ts`/api files (whose virtual
-            tsx: string;
+     * entries mirror their raw file content) are picked up by a plain
-        }
+     * `ctx.rebuild()` without recreating the esbuild context.
-    >;
+     */
+    getEntryToPage: () => Map<string, SSRVirtualEntry>;
 };
 
-export default function ssrVirtualFilesPlugin({ entryToPage }: Params) {
+export default function ssrVirtualFilesPlugin({ getEntryToPage }: Params) {
     const virtualPlugin: Plugin = {
         name: "ssr-virtual-hydration",
         setup(build) {
@@ -25,7 +27,7 @@ export default function ssrVirtualFilesPlugin({ entryToPage }: Params) {
             });
 
             build.onLoad({ filter: /.*/, namespace: "ssr-virtual" }, (args) => {
-                const target = entryToPage.get(args.path);
+                const target = getEntryToPage().get(args.path);
                 if (!target?.tsx) return null;
 
                 const contents = target.tsx;

src/functions/bunext-init.ts

@@ -16,7 +16,7 @@ import serverPostBuildFn from "./server/server-post-build-fn";
 import reactModulesBundler from "./bundler/react-modules-bundler";
 import grabConstants from "../utils/grab-constants";
 import watcherEsbuildCTX from "./server/watcher-esbuild-ctx";
-import { readFileSync, type FSWatcher } from "fs";
+import { readFileSync } from "fs";
 
 /**
  * # Declare Global Variables
@@ -35,7 +35,7 @@ declare global {
     var BUNEXT_SSR_BUNDLER_CTX_MAP: { [k: string]: BundlerCTXMap };
     // var BUNEXT_API_ROUTES_BUNDLER_CTX_MAP: { [k: string]: BundlerCTXMap };
     var BUNEXT_BUNDLER_REBUILDS: 0;
-    var BUNEXT_PAGES_SRC_WATCHER: FSWatcher | undefined;
+    var BUNEXT_PAGES_SRC_WATCHER: any;
     var BUNEXT_CURRENT_VERSION: string | undefined;
     var BUNEXT_PAGE_FILES: PageFiles[];
     var BUNEXT_ROOT_FILE_UPDATED: boolean;
@@ -54,6 +54,13 @@ declare global {
     var BUNEXT_BUILD_FAILED: boolean;
     var BUNEXT_CONSTANTS: ReturnType<typeof grabConstants>;
     var BUNEXT_MAIN_CTX_BUILD_STARTS: number;
+    /**
+     * Resolves when the one-time dev startup build (hydration + SSR for all
+     * pages) has completed. The dev server starts listening before this
+     * resolves; page requests await it so they never render against
+     * half-built modules.
+     */
+    var BUNEXT_INITIAL_BUILD_PROMISE: Promise<void> | undefined;
 }
 
 const dirNames = grabDirNames();
@@ -129,11 +136,25 @@ export default async function bunextInit(params?: Params) {
         await allPagesESBuildContextBundler({ build_only: params.build_only });
     } else if (is_dev) {
         log.build(`Building Modules ...`);
-        await allPagesESBuildContextBundler({
+
-            post_build_fn: async () => {
+        // Do NOT block on the full-site build: `Bun.serve` (or the start
-                await serverPostBuildFn();
+        // server) opens its port immediately and requests await
+        // BUNEXT_INITIAL_BUILD_PROMISE, so the site becomes reachable while
+        // the one-time compile still runs in the background.
+        const initial_build_promise = allPagesESBuildContextBundler({
+            post_build_fn: async (params) => {
+                await serverPostBuildFn(params);
             },
         });
+
+        global.BUNEXT_INITIAL_BUILD_PROMISE = initial_build_promise;
+
+        // Errors are logged (deduped) by the build pipeline itself; swallow
+        // the rejection here so it isn't an unhandled rejection.
+        initial_build_promise.catch(() => {});
+
+        // Start watching immediately so edits made during the initial build
+        // are not missed (rebuilds coalesce with the in-flight build).
         watcherEsbuildCTX();
     } else {
         if (are_modules_aready_built) {

src/functions/server/chokidar-watcher-esbuild-ctx.ts

@@ -1,161 +0,0 @@
-import chokidar from "chokidar";
-import path from "path";
-import { existsSync } from "fs";
-import grabDirNames from "../../utils/grab-dir-names";
-import fullRebuild from "./full-rebuild";
-import { AppData } from "../../data/app-data";
-import checkExcludedPatterns from "../../utils/check-excluded-patterns";
-import pagesSSRBundler from "../bundler/pages-ssr-bundler";
-import { log } from "../../utils/log";
-
-const { ROOT_DIR, BUNX_BUNDLER_ERROR_EXIT_FILE } = grabDirNames();
-
-export default async function chokadirWatcherEsbuildCTX() {
-    const watcher = chokidar.watch(ROOT_DIR, {
-        ignored: [
-            /(^|[\/\\])\../,
-            /node_modules/,
-            /public/,
-            /\.bunext/,
-            /\.git/,
-            /dist/,
-            /bun\.lockb/,
-            (path: string) => path.endsWith(AppData["BunextTmpFileExt"]),
-        ],
-        persistent: true,
-        ignoreInitial: true,
-        depth: 99,
-    });
-
-    const handleEvent = async (
-        event: "add" | "change" | "unlink" | "addDir" | "unlinkDir",
-        filePath: string,
-    ) => {
-        let owns_recompile = false;
-
-        try {
-            const filename = path.relative(ROOT_DIR, filePath);
-
-            if (existsSync(BUNX_BUNDLER_ERROR_EXIT_FILE)) {
-                await fullRebuild();
-                return;
-            }
-
-            if (global.BUNEXT_BUNDLER_CTX_DISPOSED) {
-                await fullRebuild({ msg: `Restarting Bundler ...` });
-            }
-
-            if (global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED) {
-                await pagesSSRBundler().catch((error) => {
-                    log.error(`SSR Bundler Error: ${error}`);
-                });
-            }
-
-            if (filename.match(/\/styles$/) || filename === "styles") {
-                owns_recompile = true;
-                global.BUNEXT_RECOMPILING = true;
-                await Bun.sleep(1000);
-                await fullRebuild({
-                    msg: `Detected new \`styles\` directory. Rebuilding ...`,
-                });
-                return;
-            }
-
-            if (filename.match(/bunext.config\.ts/)) {
-                await fullRebuild({
-                    msg: `bunext.config.ts file changed. Rebuilding server ...`,
-                });
-                return;
-            }
-
-            const target_files_match = /\.(tsx?|jsx?|css)$/;
-
-            if (event === "change") {
-                if (filename.match(target_files_match)) {
-                    if (global.BUNEXT_RECOMPILING) return;
-                    owns_recompile = true;
-                    global.BUNEXT_RECOMPILING = true;
-
-                    if (filename.match(/.*\.server\.tsx?/)) {
-                        global.BUNEXT_IS_SERVER_COMPONENT = true;
-                    }
-
-                    if (global.BUNEXT_BUNDLER_CTX) {
-                        await global.BUNEXT_BUNDLER_CTX.rebuild();
-                    }
-
-                    if (filename.match(/(404|500)\.tsx?/)) {
-                        for (
-                            let i = global.BUNEXT_HMR_CONTROLLERS.length - 1;
-                            i >= 0;
-                            i--
-                        ) {
-                            const controller = global.BUNEXT_HMR_CONTROLLERS[i];
-                            try {
-                                controller?.controller?.enqueue(
-                                    `event: update\ndata: ${JSON.stringify({ reload: true })}\n\n`,
-                                );
-                            } catch {
-                                global.BUNEXT_HMR_CONTROLLERS.splice(i, 1);
-                            }
-                        }
-                    }
-                }
-                return;
-            }
-
-            if (["add", "unlink", "addDir", "unlinkDir"].includes(event)) {
-                const is_file_of_interest =
-                    !!filename.match(target_files_match) ||
-                    event.includes("Dir");
-
-                if (!is_file_of_interest) return;
-
-                if (
-                    !filename.match(/^src\/pages\/|\.css$/) ||
-                    checkExcludedPatterns({ path: filename }) ||
-                    filename.includes(" ")
-                ) {
-                    return reloadWatcher();
-                }
-
-                if (global.BUNEXT_RECOMPILING) return;
-
-                owns_recompile = true;
-                const action = event.startsWith("add") ? "created" : "deleted";
-                const type = filename.match(/\.css$/)
-                    ? "Stylesheet"
-                    : event.includes("Dir")
-                      ? "Directory"
-                      : filename.match(/\/pages\/api\//)
-                        ? "API Route"
-                        : "Page";
-
-                await fullRebuild({
-                    msg: `${type} ${action}: ${filename}. Rebuilding ...`,
-                });
-            }
-        } catch (error) {
-            log.error(`Watcher rebuild failed: ${error}`);
-        } finally {
-            if (owns_recompile) {
-                global.BUNEXT_RECOMPILING = false;
-                global.BUNEXT_IS_SERVER_COMPONENT = false;
-            }
-        }
-    };
-
-    watcher
-        .on("add", (path) => handleEvent("add", path))
-        .on("change", (path) => handleEvent("change", path))
-        .on("unlink", (path) => handleEvent("unlink", path))
-        .on("addDir", (path) => handleEvent("addDir", path))
-        .on("unlinkDir", (path) => handleEvent("unlinkDir", path));
-}
-
-function reloadWatcher() {
-    if (global.BUNEXT_PAGES_SRC_WATCHER) {
-        global.BUNEXT_PAGES_SRC_WATCHER.close();
-        chokadirWatcherEsbuildCTX();
-    }
-}

src/functions/server/cleanup-artifacts.tsx

@@ -2,51 +2,111 @@ import { log } from "../../utils/log";
 import path from "path";
 import grabDirNames from "../../utils/grab-dir-names";
 import { existsSync, readdirSync, statSync, unlinkSync } from "fs";
-import type { BundlerCTXMap } from "../../types";
 
 type Params = {
-    new_artifacts: BundlerCTXMap[];
+    paradigm: "hydration" | "ssr";
 };
 
-const { ROOT_DIR, HYDRATION_DST_DIR_MAP_JSON_FILE_NAME } = grabDirNames();
+const { ROOT_DIR, HYDRATION_DST_DIR, BUNX_CWD_MODULE_CACHE_DIR } =
+    grabDirNames();
+
+// esbuild's content hashes are 8-char base64-ish (e.g. `CMSI7VSQ`). Entry
+// outputs are `<dir>/<hash>.js` / `<dir>/<hash>.css`. Shared chunks are
+// `chunk-*.js` and MUST be kept: any current entry may still reference an
+// older chunk (esbuild reuses unchanged chunks across rebuilds), and
+// verifying references would require parsing every entry's imports.
+const ENTRY_HASH_FILE = /^[A-Za-z0-9]{8}\.(js|css)$/;
+
+/**
+ * Deletes orphaned entry outputs left behind by previous rebuilds.
+ *
+ * After a rebuild the page/SSR artifact maps only reference the newest
+ * hashed entry files; every previously hashed entry for the same directory
+ * is provably unreferenced (generated HTML always uses the current map) and
+ * is removed. Chunks, non-hashed fallback module files and `map.json` are
+ * left untouched.
+ */
+export default async function cleanupArtifacts({ paradigm }: Params) {
+    const is_hydration = paradigm === "hydration";
+    const root_dir = is_hydration
+        ? HYDRATION_DST_DIR
+        : BUNX_CWD_MODULE_CACHE_DIR;
+    const map = is_hydration
+        ? global.BUNEXT_BUNDLER_CTX_MAP
+        : global.BUNEXT_SSR_BUNDLER_CTX_MAP;
+
+    if (!map || !existsSync(root_dir)) {
+        return;
+    }
 
-export default async function cleanupArtifacts({ new_artifacts }: Params) {
     try {
-        for (let i = 0; i < new_artifacts.length; i++) {
+        const keep_by_dir = new Map<string, Set<string>>();
-            const new_artifact = new_artifacts[i];
 
-            const artifact_public_dir = path.dirname(
+        for (const entry of Object.values(map)) {
-                path.join(ROOT_DIR, new_artifact.path),
+            if (!entry?.path) continue;
-            );
 
-            const dir_content = readdirSync(artifact_public_dir);
+            const full_path = path.join(ROOT_DIR, entry.path);
-
+            const dir_path = path.dirname(full_path);
-            for (let d = 0; d < dir_content.length; d++) {
+            let keep = keep_by_dir.get(dir_path);
-                const dir_or_file = dir_content[d];
+            if (!keep) {
-                const full_path = path.join(artifact_public_dir, dir_or_file);
+                keep = new Set<string>();
-
+                keep_by_dir.set(dir_path, keep);
-                const file_or_path_stats = statSync(full_path);
-
-                if (
-                    file_or_path_stats.isDirectory() ||
-                    dir_or_file == HYDRATION_DST_DIR_MAP_JSON_FILE_NAME
-                ) {
-                    continue;
             }
 
-                if (
+            keep.add(path.basename(full_path));
-                    new_artifact.path.includes(dir_or_file) ||
+
-                    new_artifact.css_path?.includes(dir_or_file)
+            if (entry.css_path) {
-                ) {
+                keep.add(path.basename(entry.css_path));
-                    continue;
+            }
         }
 
-                if (existsSync(full_path)) {
+        sweepDir(root_dir, keep_by_dir);
-                    unlinkSync(full_path);
-                }
-            }
-        }
     } catch (error: any) {
-        log.error(error);
+        log.error(`Cleanup Artifacts Error: ${error?.message || error}`);
+    }
+}
+
+function sweepDir(
+    dir_path: string,
+    keep_by_dir: Map<string, Set<string>>,
+): void {
+    let entries: string[];
+    try {
+        entries = readdirSync(dir_path);
+    } catch (error) {
+        return;
+    }
+
+    for (const name of entries) {
+        const full_path = path.join(dir_path, name);
+
+        let is_dir = false;
+        try {
+            is_dir = statSync(full_path).isDirectory();
+        } catch (error) {
+            continue;
+        }
+
+        if (is_dir) {
+            sweepDir(full_path, keep_by_dir);
+            continue;
+        }
+
+        if (!name.match(ENTRY_HASH_FILE)) {
+            continue;
+        }
+
+        if (name.startsWith("chunk-")) {
+            continue;
+        }
+
+        const keep = keep_by_dir.get(path.dirname(full_path));
+        if (keep?.has(name)) {
+            continue;
+        }
+
+        try {
+            unlinkSync(full_path);
+        } catch (error) {}
     }
 }

src/functions/server/full-rebuild.ts

@@ -51,8 +51,8 @@ async function doFullRebuild(params?: { msg?: string }) {
         } catch (error) {}
 
         await allPagesESBuildContextBundler({
-            post_build_fn: async () => {
+            post_build_fn: async (params) => {
-                await serverPostBuildFn();
+                await serverPostBuildFn(params);
             },
         });
     } catch (error: any) {

src/functions/server/server-post-build-fn.ts

@@ -4,6 +4,15 @@ import grabPageComponent from "./web-pages/grab-page-component";
 
 type Params = {
     reload_all_controllers?: boolean;
+    /**
+     * Relative page paths whose client entry outputs changed in the last
+     * build. When provided with at least one entry, only controllers
+     * targeting those pages are re-rendered/re-pushed. When empty or
+     * omitted, every controller is refreshed (covers server-file-only
+     * changes, where hydration outputs are untouched but server props must
+     * still be re-fetched).
+     */
+    changed_pages?: string[];
 };
 
 export default async function serverPostBuildFn(params?: Params) {
@@ -11,6 +20,11 @@ export default async function serverPostBuildFn(params?: Params) {
         return;
     }
 
+    const changed_set =
+        params?.changed_pages && params.changed_pages.length > 0
+            ? new Set(params.changed_pages)
+            : undefined;
+
     const reload_payload = { reload: true };
     const reload_enqueue = `event: update\ndata: ${JSON.stringify(reload_payload)}\n\n`;
 
@@ -25,6 +39,11 @@ export default async function serverPostBuildFn(params?: Params) {
             continue;
         }
 
+        // Only touch controllers whose page actually changed.
+        if (changed_set && !changed_set.has(controller.target_map.local_path)) {
+            continue;
+        }
+
         if (params?.reload_all_controllers) {
             try {
                 controller.controller.enqueue(reload_enqueue);

src/functions/server/watcher-esbuild-ctx.ts

@@ -1,10 +1,12 @@
-import { watch, existsSync, statSync, glob } from "fs";
+import chokidar from "chokidar";
 import path from "path";
+import { existsSync } from "fs";
 import grabDirNames from "../../utils/grab-dir-names";
 import fullRebuild from "./full-rebuild";
 import { AppData } from "../../data/app-data";
 import checkExcludedPatterns from "../../utils/check-excluded-patterns";
-import pagesSSRBundler from "../bundler/pages-ssr-bundler";
+import allPagesESBuildContextBundler from "../bundler/all-pages-esbuild-context-bundler";
+import serverPostBuildFn from "./server-post-build-fn";
 import { log } from "../../utils/log";
 import { logBuildErrorsOnce } from "../../utils/build-error-log";
 
@@ -24,7 +26,9 @@ export function restartWatcher() {
 
     if (Date.now() - last_watcher_restart < 1000) return;
 
+    try {
         global.BUNEXT_PAGES_SRC_WATCHER.close();
+    } catch (error) {}
     global.BUNEXT_PAGES_SRC_WATCHER = undefined;
     last_watcher_restart = Date.now();
     watcherEsbuildCTX();
@@ -38,111 +42,73 @@ export function watcherRestartAvailable() {
     return Date.now() - last_watcher_restart > 6000;
 }
 
-export default async function watcherEsbuildCTX() {
+const TARGET_FILES_MATCH = /\.(tsx?|jsx?|css)$/;
-    const pages_src_watcher = watch(
+
-        ROOT_DIR,
+// Rebuild coalescing: editors emit bursts of events per save (change +
-        {
+// atomic-swap noise), and edits can land while a rebuild is running.
-            recursive: true,
+// Events are debounced into a single runner; the runner loops until the
-            persistent: true,
+// event queue drains, so a mid-build edit is never silently dropped.
-        },
+const REBUILD_DEBOUNCE_MS = 200;
-        async (event, filename) => {
+let pending_structural = false;
-            let owns_recompile = false;
+let pending_content_file: string | undefined = undefined;
+let debounce_timer: ReturnType<typeof setTimeout> | undefined = undefined;
+
+function scheduleRebuild() {
+    if (debounce_timer) {
+        clearTimeout(debounce_timer);
+    }
+    debounce_timer = setTimeout(async () => {
+        debounce_timer = undefined;
+        try {
+            await runRebuilds();
+        } catch (error: any) {
+            const msg = String(error?.message || error || "");
+            if (!msg.startsWith("Build failed with")) {
+                logBuildErrorsOnce(
+                    [{ text: `Watcher rebuild failed: ${msg}` }],
+                    (line) => log.error(line),
+                );
+            }
+        } finally {
+            global.BUNEXT_RECOMPILING = false;
+            global.BUNEXT_IS_SERVER_COMPONENT = false;
+        }
+    }, REBUILD_DEBOUNCE_MS);
+}
+
+/**
+ * Processes the pending event batch. Structural changes go through the
+ * all-pages bundler (which re-creates esbuild contexts only when the entry
+ * set really changed, so atomic-swap saves resolve to incremental rebuilds).
+ * Content changes rebuild the hydration context incrementally; its artifact
+ * tracker then queues the single-flighted SSR rebuild and pushes HMR updates.
+ */
+async function runRebuilds() {
+    if (global.BUNEXT_RECOMPILING) {
+        return;
+    }
+    global.BUNEXT_RECOMPILING = true;
+    global.BUNEXT_IS_SERVER_COMPONENT = false;
 
     try {
-                if (!filename) return;
+        while (true) {
-                const full_file_path = path.join(ROOT_DIR, filename);
+            const structural = pending_structural;
+            const content_file = pending_content_file;
+            pending_structural = false;
+            pending_content_file = undefined;
 
-                if (global.BUNEXT_CONFIG.exclude_watch_patterns) {
+            if (!structural && !content_file) {
-                    for (
+                break;
-                        let i = 0;
-                        i < global.BUNEXT_CONFIG.exclude_watch_patterns.length;
-                        i++
-                    ) {
-                        const watch_pattern =
-                            global.BUNEXT_CONFIG.exclude_watch_patterns[i];
-
-                        if (watch_pattern instanceof RegExp) {
-                            const is_path_excluded =
-                                watch_pattern.test(filename);
-                            if (is_path_excluded) {
-                                return;
-                            }
-                        } else {
-                            const excluded_path = path.resolve(
-                                ROOT_DIR,
-                                watch_pattern,
-                            );
-
-                            if (excluded_path == full_file_path) {
-                                return;
-                            }
-                        }
-                    }
             }
 
-                if (existsSync(BUNX_BUNDLER_ERROR_EXIT_FILE)) {
+            if (structural) {
-                    await fullRebuild();
+                global.BUNEXT_ROUTER.reload();
-                    return;
+                await allPagesESBuildContextBundler({
-                }
+                    post_build_fn: async (params) => {
-
+                        await serverPostBuildFn(params);
-                if (filename.match(/^\.\w+/)) {
+                    },
-                    return;
-                }
-
-                if (global.BUNEXT_BUNDLER_CTX_DISPOSED) {
-                    await fullRebuild({ msg: `Restarting Bundler ...` });
-                    return;
-                }
-
-                if (global.BUNEXT_SSR_BUNDLER_CTX_DISPOSED) {
-                    await pagesSSRBundler().catch((error) => {
-                        log.error(`SSR Bundler Error: ${error}`);
                 });
-                }
+            } else if (content_file) {
-
-                if (filename.endsWith(AppData["BunextTmpFileExt"])) {
-                    return;
-                }
-
-                const does_file_exist = existsSync(full_file_path);
-                const file_stat = does_file_exist
-                    ? statSync(full_file_path)
-                    : undefined;
-
-                if (full_file_path.match(/\/styles$/)) {
-                    owns_recompile = true;
-                    global.BUNEXT_RECOMPILING = true;
-                    await Bun.sleep(1000);
-                    await fullRebuild({
-                        msg: `Detected new \`styles\` directory. Rebuilding ...`,
-                    });
-                    return;
-                }
-
-                const excluded_match =
-                    /node_modules\/|^public\/|^\.bunext\/|^\.git\/|^\.?dist\/|bun\.lockb$/;
-
-                if (filename.match(excluded_match)) return;
-
-                if (filename.match(/bunext.config\.ts/)) {
-                    await fullRebuild({
-                        msg: `bunext.config.ts file changed. Rebuilding server ...`,
-                    });
-                    return;
-                }
-
-                const target_files_match = /\.(tsx?|jsx?|css)$/;
-
-                if (event !== "rename") {
-                    if (filename.match(target_files_match)) {
-                        if (global.BUNEXT_RECOMPILING) return;
-                        owns_recompile = true;
-                        global.BUNEXT_RECOMPILING = true;
-
-                        if (filename.match(/.*\.server\.tsx?/)) {
-                            global.BUNEXT_IS_SERVER_COMPONENT = true;
-                        }
-
                 if (
                     global.BUNEXT_BUNDLER_CTX &&
                     !global.BUNEXT_BUNDLER_CTX_DISPOSED
@@ -152,18 +118,16 @@ export default async function watcherEsbuildCTX() {
                     await fullRebuild({
                         msg: `Restarting Bundler ...`,
                     });
-                            return;
+                    break;
                 }
 
-                        if (filename.match(/(404|500)\.tsx?/)) {
+                if (content_file.match(/(404|500)\.tsx?$/)) {
                     for (
-                                let i =
+                        let i = global.BUNEXT_HMR_CONTROLLERS.length - 1;
-                                    global.BUNEXT_HMR_CONTROLLERS.length - 1;
                         i >= 0;
                         i--
                     ) {
-                                const controller =
+                        const controller = global.BUNEXT_HMR_CONTROLLERS[i];
-                                    global.BUNEXT_HMR_CONTROLLERS[i];
                         try {
                             controller?.controller?.enqueue(
                                 `event: update\ndata: ${JSON.stringify({ reload: true })}\n\n`,
@@ -174,60 +138,168 @@ export default async function watcherEsbuildCTX() {
                     }
                 }
             }
+        }
+    } finally {
+        global.BUNEXT_RECOMPILING = false;
+        global.BUNEXT_IS_SERVER_COMPONENT = false;
+    }
+}
+
+function isPathExcluded(filename: string, full_file_path: string): boolean {
+    const user_patterns = global.BUNEXT_CONFIG?.exclude_watch_patterns;
+    if (!user_patterns) return false;
+
+    for (let i = 0; i < user_patterns.length; i++) {
+        const watch_pattern = user_patterns[i];
+        if (watch_pattern instanceof RegExp) {
+            if (watch_pattern.test(filename)) return true;
+        } else {
+            const excluded_path = path.resolve(ROOT_DIR, watch_pattern);
+            if (excluded_path == full_file_path) return true;
+        }
+    }
+    return false;
+}
+
+// Heavy directories are filtered at the watcher level so inotify doesn't
+// install watches (and deliver events) for trees the bundler never reads.
+function buildIgnoredPatterns() {
+    const ignored: Array<RegExp | ((p: string) => boolean)> = [
+        /(^|[\/\\])\../,
+        /(^|[\/\\])node_modules([\/\\]|$)/,
+        /(^|[\/\\])public([\/\\]|$)/,
+        /(^|[\/\\])\.bunext([\/\\]|$)/,
+        /(^|[\/\\])\.git([\/\\]|$)/,
+        /(^|[\/\\])dist([\/\\]|$)/,
+        /bun\.lockb$/,
+        (p: string) => p.endsWith(AppData["BunextTmpFileExt"]),
+    ];
+
+    const user_patterns = global.BUNEXT_CONFIG?.exclude_watch_patterns;
+    if (user_patterns) {
+        for (let i = 0; i < user_patterns.length; i++) {
+            const pattern = user_patterns[i];
+            if (pattern instanceof RegExp) {
+                ignored.push((p: string) =>
+                    pattern.test(path.relative(ROOT_DIR, p)),
+                );
+            } else {
+                const excluded_path = path.resolve(ROOT_DIR, pattern);
+                ignored.push((p: string) => p === excluded_path);
+            }
+        }
+    }
+
+    return ignored;
+}
+
+export default async function watcherEsbuildCTX() {
+    const pages_src_watcher = chokidar.watch(ROOT_DIR, {
+        ignored: buildIgnoredPatterns(),
+        persistent: true,
+        ignoreInitial: true,
+    });
+
+    watcherHandlers(
+        pages_src_watcher,
+        (event, filePath) => handleEvent(event, filePath),
+    );
+
+    global.BUNEXT_PAGES_SRC_WATCHER = pages_src_watcher as any;
+}
+
+function handleEvent(
+    event: "add" | "change" | "unlink" | "addDir" | "unlinkDir",
+    filePath: string,
+) {
+    try {
+        const filename = path.relative(ROOT_DIR, filePath);
+        const full_file_path = filePath;
+
+        if (isPathExcluded(filename, full_file_path)) {
             return;
         }
 
+        if (existsSync(BUNX_BUNDLER_ERROR_EXIT_FILE)) {
+            fullRebuild();
+            return;
+        }
+
+        if (filename.endsWith(AppData["BunextTmpFileExt"])) {
+            return;
+        }
+
+        if (full_file_path.match(/\/styles$/)) {
+            pending_structural = false;
+            pending_content_file = undefined;
+            if (debounce_timer) clearTimeout(debounce_timer);
+            setTimeout(() => {
+                fullRebuild({
+                    msg: `Detected new \`styles\` directory. Rebuilding ...`,
+                });
+            }, 1000);
+            return;
+        }
+
+        if (filename.match(/bunext\.config\.ts/)) {
+            pending_structural = false;
+            pending_content_file = undefined;
+            if (debounce_timer) clearTimeout(debounce_timer);
+            fullRebuild({
+                msg: `bunext.config.ts file changed. Rebuilding server ...`,
+            });
+            return;
+        }
+
+        if (event === "change") {
+            if (filename.match(TARGET_FILES_MATCH)) {
+                pending_content_file = full_file_path;
+                scheduleRebuild();
+            }
+            return;
+        }
+
+        // add / unlink / addDir / unlinkDir
+        const is_dir_event = event === "addDir" || event === "unlinkDir";
         const is_file_of_interest =
-                    Boolean(filename.match(target_files_match)) ||
+            Boolean(filename.match(TARGET_FILES_MATCH)) || is_dir_event;
-                    file_stat?.isDirectory();
 
         if (!is_file_of_interest) {
             return;
         }
 
-                if (!filename.match(/^src\/pages\/|\.css$/))
+        // Only page routes and stylesheets are structural; anything else
-                    return reloadWatcher();
+        // (e.g. a component being added) is covered by the next content
-                if (checkExcludedPatterns({ path: filename }))
+        // rebuild and needs no context recreation.
-                    return reloadWatcher();
+        if (
-                if (filename.match(/ /)) return reloadWatcher();
+            !filename.match(/^src\/pages\/|\.css$/) ||
+            checkExcludedPatterns({ path: filename }) ||
+            filename.match(/ /)
+        ) {
+            return;
+        }
 
-                if (global.BUNEXT_RECOMPILING) return;
+        pending_structural = true;
-
+        scheduleRebuild();
-                owns_recompile = true;
-                const action = does_file_exist ? "created" : "deleted";
-                const type = filename.match(/\.css$/)
-                    ? "Sylesheet"
-                    : file_stat?.isDirectory()
-                      ? "Directory"
-                      : filename.match(/\/pages\/api\//)
-                        ? "API Route"
-                        : "Page";
-
-                await fullRebuild({
-                    msg: `${type} ${action}: ${filename}. Rebuilding ...`,
-                });
     } catch (error: any) {
-                // A "Build failed with N errors" rejection is the same
-                // failure the tracker's onEnd already reported (deduped).
-                const msg = String(error?.message || error || "");
-                if (!msg.startsWith("Build failed with")) {
         logBuildErrorsOnce(
-                        [{ text: `Watcher rebuild failed: ${msg}` }],
+            [{ text: `Watcher error: ${error?.message || error}` }],
             (line) => log.error(line),
         );
     }
-            } finally {
-                if (owns_recompile) {
-                    global.BUNEXT_RECOMPILING = false;
-                    global.BUNEXT_IS_SERVER_COMPONENT = false;
-                }
-            }
-        },
-    );
-
-    global.BUNEXT_PAGES_SRC_WATCHER = pages_src_watcher;
 }
 
-function reloadWatcher() {
+function watcherHandlers(
-    restartWatcher();
+    watcher: ReturnType<typeof chokidar.watch>,
+    handleEvent: (
+        event: "add" | "change" | "unlink" | "addDir" | "unlinkDir",
+        filePath: string,
+    ) => void,
+) {
+    watcher
+        .on("add", (p) => handleEvent("add", p))
+        .on("change", (p) => handleEvent("change", p))
+        .on("unlink", (p) => handleEvent("unlink", p))
+        .on("addDir", (p) => handleEvent("addDir", p))
+        .on("unlinkDir", (p) => handleEvent("unlinkDir", p));
 }

src/functions/server/web-pages/handle-web-pages.tsx

@@ -34,6 +34,15 @@ export default async function handleWebPages({
             }
         }
 
+        // The dev server port opens before the one-time startup build
+        // finishes. First page render waits for it so we never serve HTML
+        // against half-built hydration/SSR modules.
+        if (is_dev && global.BUNEXT_INITIAL_BUILD_PROMISE) {
+            try {
+                await global.BUNEXT_INITIAL_BUILD_PROMISE;
+            } catch (error) {}
+        }
+
         const componentRes = await grabPageComponent({
             req,
         });