@@ -0,0 +1,19 @@
+---
+'@objectstack/cli': patch
+---
+
+Clause-②: no
+
+`os init` (every template: `app`, `plugin`, `empty`) and `os create plugin` now emit
+`"overrides": { "vitest": "~4.0.0" }` in the scaffolded `package.json`, so the project installs on
+npm 10, the npm Node 22 bundles. Since vitest 4.1.12 shipped a peer set that contradicts itself,
+`npm install` of a fresh `os init` project crashed on npm 10.9.x with
+`Cannot read properties of null (reading 'edgesOut')`. The override routes every `vitest` edge in
+the npm graph to the range the scaffold declares; npm 11 installs the same tree, and pnpm ignores
+the field.
+
+The override equals `devDependencies.vitest` wherever the manifest declares vitest directly,
+because npm refuses an override that differs from the direct dependency (`EOVERRIDE`). In an `app`
+or `empty` project, add vitest at the same range (`npm install -D vitest@~4.0.0`); a bare
+`npm install -D vitest` is refused with `EOVERRIDE` while the override is in place. Existing
+projects can add the same `overrides` block by hand. `os create plugin --in-repo` is unchanged.
@@ -134,6 +134,7 @@ import {
   NPM_PACKAGE_NAME_MAX_LENGTH,
   renderPnpmWorkspaceYaml,
   renderScaffoldTsconfig,
+  SCAFFOLD_NPM_OVERRIDES,
   SCAFFOLD_PNPM_RANGE,
   SCAFFOLD_TSCONFIG_INCLUDE_SRC_ONLY,
   SCAFFOLD_TYPES_NODE_RANGE,
@@ -408,6 +409,13 @@ export const templates: Record<string, CreateTemplate> = {
             typescript: SCAFFOLD_TYPESCRIPT_RANGE,
             vitest: SCAFFOLD_VITEST_RANGE,
           },
+          // The same npm override `os init` emits, from the same constant, so
+          // it always equals `devDependencies.vitest` above (npm refuses one
+          // that differs: `EOVERRIDE`) — see SCAFFOLD_NPM_OVERRIDES for the
+          // npm 10 crash it prevents. Standalone only: npm reads `overrides`
+          // from the ROOT manifest alone and pnpm never reads it, so inside
+          // this monorepo's workspace the block would be inert.
+          ...(standalone ? { overrides: { ...SCAFFOLD_NPM_OVERRIDES } } : {}),
         }),
         'tsconfig.json': (name: string) =>
           standalone
 
@@ -390,9 +390,13 @@ export const SCAFFOLD_TYPESCRIPT_RANGE = '^5.3.0';
  * `--cache` and a manifest holding only this one devDependency (the full matrix
  * is in the PR that set this value): on npm 10.9.4 and 10.9.9, `npm install`
  * exits 1 with `Cannot read properties of null (reading 'edgesOut')` from
- * arborist's `#loadPeerSet`, and npm 11.21.0 installs it. `~4.0.0` installs on
- * all three (vitest 4.0.18, vite 7.3.7), and so do both CLI-emitted plugin
- * manifests. The cost: a scaffold gets vitest 4.0.18 rather than 4.1.11.
+ * arborist's `#loadPeerSet`, and npm 11.21.0 installs it. `~4.0.0` installed on
+ * all three (vitest 4.0.18, vite 7.3.7), and so did both CLI-emitted plugin
+ * manifests. The cost: a scaffold gets vitest 4.0.18 rather than 4.1.x.
+ *
+ * ⚠️ The range alone stopped being enough, so it is also emitted as an npm
+ * OVERRIDE — see {@link SCAFFOLD_NPM_OVERRIDES}, which is built from this
+ * constant, so the declared range and the override cannot disagree.
  *
  * The cause is upstream, in the peer graph. Every vitest 4.1.x admits vite 8.
  * vite 8 declares an optional `@vitejs/devtools` peer, which reaches
@@ -415,6 +419,56 @@ export const SCAFFOLD_TYPESCRIPT_RANGE = '^5.3.0';
  */
 export const SCAFFOLD_VITEST_RANGE = '~4.0.0';
 
+/**
+ * The npm `overrides` block every STANDALONE scaffold emits: `os init`'s three
+ * templates, `os create plugin` outside the monorepo, and — by generation, not
+ * import — `create-objectstack`'s bundled template (the `overrides.vitest` row
+ * in `scripts/sync-scaffold-emission-policy.mjs`'s `POLICY_STAMPS`).
+ *
+ * Why it exists. vitest 4.1.12 (published 2026-10-15) peers
+ * `@vitest/browser-webdriverio ^4.1.11`, and that package's only match, 4.1.11,
+ * peers `vitest: 4.1.11` exactly — a peer set that contradicts itself. A
+ * scaffold reaches it even with vitest pinned to `~4.0.0` at its root, through
+ * OPTIONAL `vitest` peers deeper in the closure (`@objectstack/metadata-core`
+ * peers `^4.0.0`, better-auth peers `^2 || ^3 || ^4`), which npm 10 resolves to
+ * vitest's newest 4.x. Measured 2026-10-16, each manifest in an empty
+ * directory with a fresh `--cache`, against the published `18.0.0-next.2`:
+ *
+ *   without the override   npm 10.9.9   `os init -t app`, `-t plugin` and
+ *                                       `-t empty` all exit 1 with `Cannot
+ *                                       read properties of null (reading
+ *                                       'edgesOut')`; `os create plugin` (no
+ *                                       `@objectstack/cli` in its closure)
+ *                                       exits 0
+ *   with the override      npm 10.9.9   all four exit 0
+ *                          npm 11.21.1  all four exit 0
+ *
+ * So the override goes on EVERY template, not only the ones that declare
+ * vitest: `-t app` and `-t empty` declare none and crashed all the same,
+ * because what they share is `@objectstack/cli`. Where a manifest does declare
+ * vitest, the override equals that declaration — npm refuses an override that
+ * differs from the direct dependency's own spec (`EOVERRIDE`).
+ *
+ * The cost, measured on an emitted `-t app` (npm 10.9.9): a later bare `npm
+ * install -D vitest` is refused with `EOVERRIDE: Override for vitest@*
+ * conflicts with direct dependency`; `npm install -D vitest@~4.0.0` (this
+ * range) installs. Loud and self-describing, where the alternative was a
+ * project that could not install at all. pnpm ignores npm's `overrides` field,
+ * so pnpm users see no change.
+ *
+ * ⛔ Not `"$vitest"`: it needs a direct dependency to point at (two of the
+ * three `os init` templates have none), and where it does apply, npm stops
+ * hoisting `@objectstack/metadata-core` and nests copies of it (measured on the
+ * bundled template) — a duplicated module is a duplicated `instanceof` identity.
+ *
+ * The re-check that lets this go: the same empty-directory install of an
+ * emitted `-t app` manifest WITHOUT this block, on the newest npm 10 and on npm
+ * 11. When both exit 0, delete it here and its `POLICY_STAMPS` row together.
+ */
+export const SCAFFOLD_NPM_OVERRIDES: Readonly<Record<string, string>> = Object.freeze({
+  vitest: SCAFFOLD_VITEST_RANGE,
+});
+
 /** The `@types/node` range a scaffolded project declares. */
 export const SCAFFOLD_TYPES_NODE_RANGE = '^22.0.0';
 
@@ -495,6 +549,9 @@ export function renderScaffoldPackageJson(
     scripts: template.scripts,
     dependencies: template.dependencies,
     devDependencies: template.devDependencies,
+    // Every template, whether or not it declares vitest itself — without it
+    // npm 10 cannot install any of them (see SCAFFOLD_NPM_OVERRIDES).
+    overrides: { ...SCAFFOLD_NPM_OVERRIDES },
   };
 }
 
 
@@ -0,0 +1,110 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * PIN — every standalone manifest `os init` and `os create` emit carries the
+ * npm `overrides` block, built from the one vitest constant.
+ *
+ * ## The defect
+ *
+ * vitest 4.1.12 shipped a self-contradicting peer set (it peers
+ * `@vitest/browser-webdriverio ^4.1.11`, whose only release peers `vitest:
+ * 4.1.11` exactly). npm 10 — the npm Node 22 bundles — reaches it through
+ * OPTIONAL `vitest` peers in the `@objectstack/cli` closure, even with vitest
+ * pinned to `~4.0.0` at the project root, and its arborist crashes with
+ * `Cannot read properties of null (reading 'edgesOut')`. Measured 2026-10-16:
+ * `os init -t app`, `-t plugin` and `-t empty` all failed `npm install` on npm
+ * 10.9.9; with `"overrides": { "vitest": "~4.0.0" }` all of them, and `os
+ * create plugin`, installed on npm 10.9.9 and npm 11.21.1. The full reading is
+ * on `SCAFFOLD_NPM_OVERRIDES` in `src/commands/init.ts`.
+ *
+ * ## What is asserted, and why no range is written down here
+ *
+ * Every expectation is DERIVED from the exported constants, never a literal:
+ * a pin comparing against `'~4.0.0'` would stay green on a tree where the
+ * constant moved and one emission was left behind — the drift it exists to
+ * catch.
+ *
+ *   1. Each emission's `overrides.vitest` IS `SCAFFOLD_VITEST_RANGE`.
+ *   2. Where an emission also declares `vitest` directly, the two are equal —
+ *      npm refuses an override that differs from the direct dependency's own
+ *      spec (`EOVERRIDE`), so a mismatch is an install failure of its own.
+ *   3. `os create plugin --in-repo` emits NO `overrides`: npm reads the field
+ *      only from the root manifest and pnpm never reads it, so inside the
+ *      workspace it would be a declaration nothing honours.
+ *
+ * That the emitted manifests really install is not decidable here; the npm
+ * matrix above is the measurement, and `create-objectstack`'s bundled template
+ * reaches the same constant through `scripts/sync-scaffold-emission-policy.mjs`
+ * (`pnpm check:scaffold-emission-policy`).
+ */
+
+import { describe, it, expect } from 'vitest';
+import {
+  renderScaffoldPackageJson,
+  SCAFFOLD_NPM_OVERRIDES,
+  SCAFFOLD_VITEST_RANGE,
+  TEMPLATES,
+} from '../src/commands/init.js';
+import { DEFAULT_PLACEMENT, templates } from '../src/commands/create.js';
+
+const PROBE_NAME = 'overrides-probe';
+
+type Manifest = {
+  dependencies?: Record<string, string>;
+  devDependencies?: Record<string, string>;
+  overrides?: Record<string, string>;
+};
+
+/** Every standalone manifest the two commands emit, derived from the live maps. */
+function standaloneManifests(): Array<{ id: string; manifest: Manifest }> {
+  const out: Array<{ id: string; manifest: Manifest }> = [];
+  for (const [key, template] of Object.entries(TEMPLATES)) {
+    out.push({ id: `os init -t ${key}`, manifest: renderScaffoldPackageJson(PROBE_NAME, template) as Manifest });
+  }
+  for (const [key, template] of Object.entries(templates)) {
+    const render = template.filesFor(DEFAULT_PLACEMENT)['package.json'];
+    if (!render) continue;
+    out.push({ id: `os create ${key}`, manifest: render(PROBE_NAME) as Manifest });
+  }
+  return out;
+}
+
+describe('npm overrides in every standalone scaffold manifest', () => {
+  it('harvests every emission, and the default placement IS standalone (control)', () => {
+    expect(DEFAULT_PLACEMENT).toBe('standalone');
+    const ids = standaloneManifests().map((m) => m.id);
+    expect(ids).toEqual(expect.arrayContaining(['os init -t app', 'os init -t plugin', 'os create plugin']));
+    // Assertion 2 below must range over something, or it certifies nothing.
+    const direct = standaloneManifests().filter((m) => m.manifest.devDependencies?.vitest !== undefined);
+    expect(direct.map((m) => m.id)).toEqual(expect.arrayContaining(['os init -t plugin', 'os create plugin']));
+  });
+
+  it('the override map is built from the vitest constant', () => {
+    expect(SCAFFOLD_NPM_OVERRIDES.vitest).toBe(SCAFFOLD_VITEST_RANGE);
+    expect(Object.isFrozen(SCAFFOLD_NPM_OVERRIDES)).toBe(true);
+  });
+
+  it.each(standaloneManifests())('$id emits overrides.vitest = SCAFFOLD_VITEST_RANGE', ({ manifest }) => {
+    expect(manifest.overrides).toEqual({ ...SCAFFOLD_NPM_OVERRIDES });
+    expect(manifest.overrides?.vitest).toBe(SCAFFOLD_VITEST_RANGE);
+  });
+
+  it.each(standaloneManifests())(
+    '$id: every override naming a direct dependency equals that dependency (npm EOVERRIDE)',
+    ({ manifest }) => {
+      const direct = { ...(manifest.dependencies ?? {}), ...(manifest.devDependencies ?? {}) };
+      for (const [name, range] of Object.entries(manifest.overrides ?? {})) {
+        if (direct[name] === undefined) continue;
+        expect(range, `overrides.${name} vs the direct ${name} dependency`).toBe(direct[name]);
+      }
+    },
+  );
+
+  it('os create --in-repo emits no overrides block — npm and pnpm both ignore it in a workspace member', () => {
+    const render = templates.plugin.filesFor('in-repo')['package.json'];
+    const manifest = render(PROBE_NAME) as Manifest;
+    // Control: the in-repo manifest is a real one, with vitest declared.
+    expect(manifest.devDependencies?.vitest).toBe(SCAFFOLD_VITEST_RANGE);
+    expect(manifest).not.toHaveProperty('overrides');
+  });
+});
@@ -218,8 +218,11 @@ describe('bundled template declared version surfaces', () => {
     // The literal costs one thing instead, and loudly: npm refuses an override
     // that differs from the direct dependency's own spec (`EOVERRIDE: Override
     // for vitest@^4.1.0 conflicts with direct dependency`, measured), so the two
-    // move together. That is the second assertion. `devDependencies.vitest` is
-    // stamped from `SCAFFOLD_VITEST_RANGE` at build; this override is not.
+    // move together. That is the second assertion. Both are stamped from
+    // `SCAFFOLD_VITEST_RANGE` at build (the `devDependencies.vitest` and
+    // `overrides.vitest` rows of the emission-policy stamp script's
+    // `POLICY_STAMPS`), the constant `os init` / `os create` emit their own
+    // override from.
     // ⛔ Not a shipped `.npmrc` with `legacy-peer-deps`, which changes peer
     // resolution for every npm user of the scaffold.
     it('package.json overrides vitest to its own declared range, so npm 10 installs it', () => {