diff --git a/apps/docs/.gitignore b/apps/docs/.gitignore
new file mode 100644
index 00000000000..7c4dc796934
--- /dev/null
+++ b/apps/docs/.gitignore
@@ -0,0 +1,3 @@
+# Written by `node scripts/build-llms-full.mjs` (the `build` script): a build
+# artifact of every docs page, ~20 MB, never committed.
+/public/llms-full.txt
diff --git a/apps/docs/app/llms-full.txt/route.ts b/apps/docs/app/llms-full.txt/route.ts
deleted file mode 100644
index d494d2cbb68..00000000000
--- a/apps/docs/app/llms-full.txt/route.ts
+++ /dev/null
@@ -1,10 +0,0 @@
-import { getLLMText, source } from '@/lib/source';
-
-export const revalidate = false;
-
-export async function GET() {
-  const scan = source.getPages().map(getLLMText);
-  const scanned = await Promise.all(scan);
-
-  return new Response(scanned.join('\n\n'));
-}
diff --git a/apps/docs/next.config.mjs b/apps/docs/next.config.mjs
index 05b9429a7d5..216edb49777 100644
--- a/apps/docs/next.config.mjs
+++ b/apps/docs/next.config.mjs
@@ -104,7 +104,10 @@ const config = {
     //
     //   1. Coverage. Only the per-page markdown has an HTML twin to point a
     //      canonical at. `/llms.txt` is an index of every page and
-    //      `/llms-full.txt` is all 400+ of them concatenated (8 MB today); there
+    //      `/llms-full.txt` is all 400+ of them concatenated (20 MB in 2026-10, a
+    //      static file `scripts/build-llms-full.mjs` writes into `public/` --
+    //      the header applies there too, since Next checks headers before the
+    //      filesystem); there
     //      is no single HTML URL either one is a duplicate *of*, so a canonical
     //      header cannot say anything honest about them and would leave the two
     //      largest parallel copies on the site undirected. `noindex` states the
diff --git a/apps/docs/package.json b/apps/docs/package.json
index 8def420d6b7..9258f371dbc 100644
--- a/apps/docs/package.json
+++ b/apps/docs/package.json
@@ -6,7 +6,7 @@
   "license": "Apache-2.0",
   "scripts": {
     "dev": "next dev",
-    "build": "pnpm --filter @objectstack/spec gen:schema && pnpm --filter @objectstack/spec gen:docs && pnpm --filter @objectstack/spec gen:upgrade-guide && NODE_OPTIONS='--max-old-space-size=4096' next build",
+    "build": "pnpm --filter @objectstack/spec gen:schema && pnpm --filter @objectstack/spec gen:docs && pnpm --filter @objectstack/spec gen:upgrade-guide && node scripts/build-llms-full.mjs && NODE_OPTIONS='--max-old-space-size=4096' next build",
     "start": "next start",
     "site:lint": "next lint",
     "postinstall": "fumadocs-mdx",
diff --git a/apps/docs/scripts/build-llms-full.mjs b/apps/docs/scripts/build-llms-full.mjs
new file mode 100644
index 00000000000..82e7e0b0ff2
--- /dev/null
+++ b/apps/docs/scripts/build-llms-full.mjs
@@ -0,0 +1,101 @@
+#!/usr/bin/env node
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * Writes `public/llms-full.txt` -- every docs page's `getLLMText()`, joined by
+ * one blank line, in `source.getPages()` order -- at BUILD time, as a static
+ * file. Run by this app's `build` script, after the spec generators and before
+ * `next build`:
+ *
+ *   node scripts/build-llms-full.mjs              # writes public/llms-full.txt
+ *   node scripts/build-llms-full.mjs <out-file>   # writes elsewhere (measuring)
+ *
+ * ## Why a build-time file and not a route handler
+ *
+ * `/llms-full.txt` used to be `app/llms-full.txt/route.ts` with
+ * `revalidate = false`. `next build` prerenders such a route, and Vercel stores
+ * a prerendered route as an ISR page whose body is its fallback; the deploy API
+ * refuses a fallback body over 20 MB (`FALLBACK_BODY_TOO_LARGE`, at the
+ * `vercel deploy --prebuilt` upload, after a green build). The concatenation
+ * measured 20,032,800 bytes over 418 pages at e611e2bda, so every production
+ * docs deploy failed. A file under `public/` is not a prerender: Vercel's Next
+ * builder copies it into the build output's `static/` tree and the CDN serves
+ * it as a file, so that cap does not apply to it at any size. The URL, the body
+ * and the `X-Robots-Tag: noindex` header (`next.config.mjs` `headers()`, which
+ * Next applies before the filesystem, `public/` included) are unchanged.
+ *
+ * ## One producer
+ *
+ * The text is `getLLMText()` over `source.getPages()` from `lib/source.ts` --
+ * the module the per-page `/llms.mdx/docs/**` route and `/llms.txt` read --
+ * imported here as plain Node: fumadocs-mdx's Node loader compiles each page
+ * with the same `source.config.ts`, and `llms-full/resolve-hooks.mjs` maps the
+ * two tsconfig aliases. When this script replaced the route, its output was
+ * byte-identical (sha256) to the route's prerendered body read off the same
+ * `.source/`. A second copy of the page list or of `getLLMText` here would fork
+ * the two.
+ *
+ * Page ORDER is `source.getPages()` order, which follows the `.source/` index,
+ * and fumadocs-mdx writes that index in a different order on every run
+ * (measured: four runs on one tree, four orders) -- as it did for the route.
+ * Each build's file holds the same pages and bytes; their order may differ.
+ *
+ * ## `.source/` is regenerated first
+ *
+ * `.source/` is written by `pnpm install`'s postinstall, BEFORE the spec
+ * generators run, so it does not list pages they add: on a fresh checkout
+ * `content/docs/protocol-upgrade/` (gitignored) does not exist until
+ * `gen:upgrade-guide` writes it. `next build` regenerates `.source/` when it
+ * loads `next.config.mjs`; this script calls the same `postInstall()` first,
+ * so both read the same page set.
+ *
+ * A failure anywhere here exits non-zero and fails the build: a deploy without
+ * this file would 404 `/llms-full.txt` with no error anywhere.
+ */
+
+import { register } from 'node:module';
+import { mkdirSync, writeFileSync } from 'node:fs';
+import { dirname, join, relative, resolve, sep } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const APP_ROOT = join(dirname(fileURLToPath(import.meta.url)), '..');
+const DEFAULT_OUT = join(APP_ROOT, 'public', 'llms-full.txt');
+
+if (!process.features.typescript) {
+  console.error(
+    `build-llms-full: this Node (${process.version}) cannot load lib/source.ts: it has no ` +
+      'TypeScript type stripping. Use Node 22.18 or newer (CI and the docs deploy install the latest 22).',
+  );
+  process.exit(1);
+}
+
+const out = process.argv[2] ? resolve(process.argv[2]) : DEFAULT_OUT;
+
+// `source.config.ts` resolves the content directory against the cwd, as it
+// does under `next build`, whose cwd is this app.
+process.chdir(APP_ROOT);
+
+const { postInstall } = await import('fumadocs-mdx/next');
+await postInstall();
+
+register('./llms-full/resolve-hooks.mjs', import.meta.url);
+const { register: registerMdx } = await import('fumadocs-mdx/node');
+registerMdx();
+
+const { source, getLLMText } = await import('@/lib/source');
+
+const pages = source.getPages();
+if (pages.length === 0) {
+  console.error('build-llms-full: source.getPages() returned no pages; refusing to write an empty llms-full.txt.');
+  process.exit(1);
+}
+
+const body = (await Promise.all(pages.map(getLLMText))).join('\n\n');
+mkdirSync(dirname(out), { recursive: true });
+writeFileSync(out, body);
+
+const bytes = Buffer.byteLength(body);
+console.log(
+  `build-llms-full: ${pages.length} pages, ${bytes.toLocaleString('en-US')} bytes ` +
+    `(${(bytes / 1e6).toFixed(2)} MB) -> ${out.startsWith(APP_ROOT + sep) ? relative(APP_ROOT, out) : out}`,
+);
diff --git a/apps/docs/scripts/llms-full/resolve-hooks.mjs b/apps/docs/scripts/llms-full/resolve-hooks.mjs
new file mode 100644
index 00000000000..11fd842e404
--- /dev/null
+++ b/apps/docs/scripts/llms-full/resolve-hooks.mjs
@@ -0,0 +1,75 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * Node resolution hooks that let `scripts/build-llms-full.mjs` import
+ * `lib/source.ts` as plain Node -- the module `next build` bundles -- instead
+ * of a second copy of the page source.
+ *
+ * Each rule is the Node spelling of a resolution the Next build already does:
+ *
+ *   `fumadocs-mdx:collections/X` -> `.source/X.ts`    tsconfig.json `paths`
+ *   `@/X`                         -> `X.ts`            tsconfig.json `paths`
+ *   a bare import from a file outside this app that does not resolve there
+ *   (`lucide-react`, `react/jsx-runtime` in a compiled `content/docs/**.mdx`)
+ *                                 -> resolved from this app, which is what
+ *                                    next.config.mjs's `turbopack.resolveAlias`
+ *                                    does for the same reason: `content/` has
+ *                                    no node_modules of its own.
+ *
+ * A `.ts` file reached through an alias is loaded as an ES module with its
+ * types stripped (Node's own type stripping), so nothing here transpiles. A
+ * specifier no rule claims goes to Node unchanged, and so does one a rule
+ * cannot find on disk: a typo fails as loudly as anywhere else.
+ */
+
+import { existsSync, statSync } from 'node:fs';
+import { dirname, join } from 'node:path';
+import { fileURLToPath, pathToFileURL } from 'node:url';
+
+const APP_ROOT = join(dirname(fileURLToPath(import.meta.url)), '..', '..');
+const APP_MANIFEST_URL = pathToFileURL(join(APP_ROOT, 'package.json')).href;
+const APP_DIR_URL = pathToFileURL(`${APP_ROOT}/`).href;
+
+const ALIASES = [
+  ['fumadocs-mdx:collections/', join(APP_ROOT, '.source')],
+  ['@/', APP_ROOT],
+];
+
+function isFile(path) {
+  return existsSync(path) && statSync(path).isFile();
+}
+
+function aliasTarget(specifier) {
+  for (const [prefix, dir] of ALIASES) {
+    if (!specifier.startsWith(prefix)) continue;
+    const base = join(dir, specifier.slice(prefix.length));
+    for (const file of [base, `${base}.ts`, join(base, 'index.ts')]) {
+      if (isFile(file)) return file;
+    }
+  }
+  return null;
+}
+
+/** A package name, not a path, URL or `#` import. */
+function isBare(specifier) {
+  return !/^(?:[./#]|[a-z][a-z0-9+.-]*:)/i.test(specifier);
+}
+
+export async function resolve(specifier, context, nextResolve) {
+  const file = aliasTarget(specifier);
+  if (file) {
+    const url = pathToFileURL(file).href;
+    return file.endsWith('.ts')
+      ? { url, format: 'module-typescript', shortCircuit: true }
+      : { url, shortCircuit: true };
+  }
+  const parent = context.parentURL;
+  if (isBare(specifier) && parent?.startsWith('file:') && !parent.startsWith(APP_DIR_URL)) {
+    try {
+      return await nextResolve(specifier, context);
+    } catch {
+      return nextResolve(specifier, { ...context, parentURL: APP_MANIFEST_URL });
+    }
+  }
+  return nextResolve(specifier, context);
+}
diff --git a/turbo.json b/turbo.json
index 341e2ebfd81..7c60860de7a 100644
--- a/turbo.json
+++ b/turbo.json
@@ -36,7 +36,7 @@
     },
     "@objectstack/docs#build": {
       "dependsOn": ["^build"],
-      "outputs": ["dist/**", "json-schema/**", ".next/**", "!.next/cache/**"],
+      "outputs": ["dist/**", "json-schema/**", ".next/**", "!.next/cache/**", "public/llms-full.txt"],
       "inputs": ["$TURBO_DEFAULT$", "$TURBO_ROOT$/content/**"]
     },
     "@objectstack/skills#build": {