diff --git a/bin/crawlproof.ts b/bin/crawlproof.ts
index 9b07826..8347d8a 100755
--- a/bin/crawlproof.ts
+++ b/bin/crawlproof.ts
@@ -64,9 +64,14 @@ async function main(argv: string[]): Promise<number> {
     const result = await install(spec);
     if (!result.ok) {
       process.stderr.write('crawlproof: could not install the dashboard.\n');
+      // An install that exited 0 and left the wrong version behind is the
+      // confusing case, so the reason goes out rather than just the failure.
+      if (result.note) process.stderr.write(`  ${result.note}\n`);
       return 1;
     }
-    process.stdout.write(`crawlproof: installed with ${result.manager}\n`);
+    process.stdout.write(
+      `crawlproof: installed ${result.version ?? ''} with ${result.manager}\n`.replace('  ', ' '),
+    );
     return 0;
   }
 
diff --git a/bin/hqtui.ts b/bin/hqtui.ts
index e3afedc..3751ce6 100755
--- a/bin/hqtui.ts
+++ b/bin/hqtui.ts
@@ -57,9 +57,14 @@ async function main(argv: string[]): Promise<number> {
     const result = await install(spec);
     if (!result.ok) {
       process.stderr.write('hqtui: could not install the dashboard.\n');
+      // An install that exited 0 and left the wrong version behind is the
+      // confusing case, so the reason goes out rather than just the failure.
+      if (result.note) process.stderr.write(`  ${result.note}\n`);
       return 1;
     }
-    process.stdout.write(`hqtui: installed with ${result.manager}\n`);
+    process.stdout.write(
+      `hqtui: installed ${result.version ?? ''} with ${result.manager}\n`.replace('  ', ' '),
+    );
     return 0;
   }
 
diff --git a/src/crawlproof.ts b/src/crawlproof.ts
index 3f3f67f..0000e2b 100644
--- a/src/crawlproof.ts
+++ b/src/crawlproof.ts
@@ -29,6 +29,7 @@ import { homedir } from 'node:os';
 import { join } from 'node:path';
 import { onPath, resolveCommand } from './registry.ts';
 import { spawnInherit } from './codeburn.ts';
+import { delivered, heldBackNote, installedVersion, wantedVersion } from './vendor-verify.ts';
 
 /** The published package, and the executable it installs. */
 export const PACKAGE = '@profullstack/crawlproof';
@@ -161,6 +162,10 @@ export interface InstallResult {
   ok: boolean;
   manager?: PackageManager;
   code?: number | null;
+  /** What actually landed, when it could be read. */
+  version?: string;
+  /** Why an install that exited 0 was not accepted. */
+  note?: string;
 }
 
 /** Install (or refresh) the dashboard in the private prefix. */
@@ -172,12 +177,26 @@ export async function install(
   const root = vendorRoot(env);
   prepareVendorDir(root);
 
+  // What this install is supposed to produce, asked once rather than per
+  // manager. Null means the registry was unreachable, and an unverifiable
+  // install is allowed through: an offline box should still be able to
+  // reinstall what it already has.
+  const wanted = await wantedVersion(spec, PACKAGE);
+  let lastNote: string | undefined;
+
   for (const manager of managers(env)) {
     const plan = installPlan(manager, spec);
     const code = await run(plan.file, plan.args, root);
-    if (code === 0) return { ok: true, manager, code };
+    if (code !== 0) continue;
+
+    // Exit 0 is not proof. See src/vendor-verify.ts: pnpm's release-age
+    // cooldown installs the previous version and reports success.
+    const got = installedVersion(root, PACKAGE);
+    if (delivered(got, wanted)) return { ok: true, manager, code, ...(got ? { version: got } : {}) };
+    lastNote = heldBackNote(manager, got, wanted);
   }
-  return { ok: false };
+
+  return { ok: false, ...(lastNote ? { note: lastNote } : {}) };
 }
 
 /**
diff --git a/src/hqtui.ts b/src/hqtui.ts
index 0df54c7..472dc37 100644
--- a/src/hqtui.ts
+++ b/src/hqtui.ts
@@ -34,6 +34,7 @@ import { homedir } from 'node:os';
 import { join } from 'node:path';
 import { onPath, resolveCommand } from './registry.ts';
 import { spawnInherit } from './codeburn.ts';
+import { delivered, heldBackNote, installedVersion, wantedVersion } from './vendor-verify.ts';
 
 /** The published package, and the executable it installs. */
 export const PACKAGE = '@profullstack/hqtui-demo';
@@ -173,6 +174,10 @@ export interface InstallResult {
   ok: boolean;
   manager?: PackageManager;
   code?: number | null;
+  /** What actually landed, when it could be read. */
+  version?: string;
+  /** Why an install that exited 0 was not accepted. */
+  note?: string;
 }
 
 /** Install (or refresh) the dashboard in the private prefix. */
@@ -184,10 +189,24 @@ export async function install(
   const root = vendorRoot(env);
   prepareVendorDir(root);
 
+  // What this install is supposed to produce, asked once rather than per
+  // manager. Null means the registry was unreachable, and an unverifiable
+  // install is allowed through: an offline box should still be able to
+  // reinstall what it already has.
+  const wanted = await wantedVersion(spec, PACKAGE);
+  let lastNote: string | undefined;
+
   for (const manager of managers(env)) {
     const plan = installPlan(manager, spec);
     const code = await run(plan.file, plan.args, root);
-    if (code === 0) return { ok: true, manager, code };
+    if (code !== 0) continue;
+
+    // Exit 0 is not proof. See src/vendor-verify.ts: pnpm's release-age
+    // cooldown installs the previous version and reports success.
+    const got = installedVersion(root, PACKAGE);
+    if (delivered(got, wanted)) return { ok: true, manager, code, ...(got ? { version: got } : {}) };
+    lastNote = heldBackNote(manager, got, wanted);
   }
-  return { ok: false };
+
+  return { ok: false, ...(lastNote ? { note: lastNote } : {}) };
 }
diff --git a/src/vendor-verify.ts b/src/vendor-verify.ts
new file mode 100644
index 0000000..860a4b0
--- /dev/null
+++ b/src/vendor-verify.ts
@@ -0,0 +1,98 @@
+/**
+ * Did the install actually install anything?
+ *
+ * Exit code 0 is not proof. pnpm 11 ships a `minimumReleaseAge` cooldown that
+ * refuses versions published in the last little while, and it does not fail
+ * when it refuses one: it resolves to the newest version old enough to pass,
+ * prints a note about an exclude list, and exits 0. So `pnpm add pkg@latest`
+ * against a package published ten minutes ago installs the previous release and
+ * reports success.
+ *
+ * Reproduced on 2026-09-06 in an empty directory, pnpm 11.18.0:
+ *
+ *     registry latest: 0.2.0
+ *     pnpm add @profullstack/crawlproof@latest  -> 0.1.0, exit 0
+ *     npm install @profullstack/crawlproof@latest -> 0.2.0
+ *
+ * The failure mode is the bad one. Someone runs `update`, is told it worked,
+ * and keeps hitting the bug it was supposed to fix. So the wrappers ask what
+ * landed instead of trusting the exit code, and move to the next package
+ * manager when the answer is the wrong version.
+ *
+ * Deliberately not `--config.minimumReleaseAge=0`. The cooldown is a real
+ * supply-chain protection and turning it off wholesale in a tool that installs
+ * on other people's machines is a bigger decision than fixing an update.
+ * Falling through to npm keeps the protection as pnpm's default behaviour and
+ * still lets a deliberate `update` finish.
+ */
+
+import { existsSync, readFileSync } from 'node:fs';
+import path from 'node:path';
+
+import { run } from './exec.ts';
+
+/** The version actually present in a vendor prefix, or null when nothing is. */
+export function installedVersion(root: string, pkg: string): string | null {
+  const manifest = path.join(root, 'node_modules', ...pkg.split('/'), 'package.json');
+  if (!existsSync(manifest)) return null;
+  try {
+    const version = (JSON.parse(readFileSync(manifest, 'utf8')) as { version?: string }).version;
+    return typeof version === 'string' && version ? version : null;
+  } catch {
+    return null;
+  }
+}
+
+/**
+ * The exact version a spec asks for, when it names one.
+ *
+ * `pkg@1.2.3` is answerable here; `pkg@latest` and `pkg@^1` are not, and
+ * return null so the caller asks the registry instead of guessing.
+ */
+export function pinnedVersion(spec: string): string | null {
+  const at = spec.lastIndexOf('@');
+  if (at <= 0) return null;
+  const tag = spec.slice(at + 1);
+  return /^\d+\.\d+\.\d+/.test(tag) ? tag : null;
+}
+
+/** What the registry calls latest, or null when it cannot be reached. */
+export async function registryLatest(
+  pkg: string,
+  exec: typeof run = run,
+): Promise<string | null> {
+  const result = await exec('npm', ['view', pkg, 'version'], { timeoutMs: 60_000 });
+  if (result.code !== 0) return null;
+  const version = result.stdout.trim().split('\n').pop()?.trim() ?? '';
+  return /^\d+\.\d+\.\d+/.test(version) ? version : null;
+}
+
+/**
+ * The version this install was supposed to produce.
+ *
+ * A pinned spec answers itself. `@latest` has to be asked, and when the
+ * registry cannot be reached the answer is null, which callers must read as
+ * "cannot verify" rather than as "wrong version" — an offline box should still
+ * be able to reinstall what it already has.
+ */
+export async function wantedVersion(
+  spec: string,
+  pkg: string,
+  exec: typeof run = run,
+): Promise<string | null> {
+  return pinnedVersion(spec) ?? (await registryLatest(pkg, exec));
+}
+
+/** Whether what landed is what was asked for. Unknown wants pass. */
+export function delivered(installed: string | null, wanted: string | null): boolean {
+  if (wanted === null) return true;
+  return installed === wanted;
+}
+
+/** What to say when a manager reported success and delivered something older. */
+export function heldBackNote(manager: string, installed: string | null, wanted: string | null): string {
+  return (
+    `${manager} reported success but left ${installed ?? 'nothing'} installed, not ${wanted}. ` +
+    `pnpm holds back very recent releases; trying the next package manager.`
+  );
+}
diff --git a/test/vendor-verify.test.ts b/test/vendor-verify.test.ts
new file mode 100644
index 0000000..952dcfe
--- /dev/null
+++ b/test/vendor-verify.test.ts
@@ -0,0 +1,113 @@
+import { describe, expect, it } from 'vitest';
+import { mkdirSync, mkdtempSync, rmSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import path from 'node:path';
+
+import {
+  delivered,
+  heldBackNote,
+  installedVersion,
+  pinnedVersion,
+  registryLatest,
+  wantedVersion,
+} from '../src/vendor-verify.ts';
+
+function prefixWith(pkg: string, version: string | null): string {
+  const root = mkdtempSync(path.join(tmpdir(), 'vendor-verify-'));
+  if (version !== null) {
+    const dir = path.join(root, 'node_modules', ...pkg.split('/'));
+    mkdirSync(dir, { recursive: true });
+    writeFileSync(path.join(dir, 'package.json'), JSON.stringify({ name: pkg, version }));
+  }
+  return root;
+}
+
+const fakeExec = (stdout: string, code = 0) =>
+  (async () => ({ code, stdout, stderr: '' })) as never;
+
+describe('installedVersion', () => {
+  it('reads what is actually on disk', () => {
+    const root = prefixWith('@profullstack/crawlproof', '0.1.0');
+    try {
+      expect(installedVersion(root, '@profullstack/crawlproof')).toBe('0.1.0');
+    } finally {
+      rmSync(root, { recursive: true, force: true });
+    }
+  });
+
+  it('is null when nothing is installed, rather than throwing', () => {
+    const root = prefixWith('@profullstack/crawlproof', null);
+    try {
+      expect(installedVersion(root, '@profullstack/crawlproof')).toBeNull();
+    } finally {
+      rmSync(root, { recursive: true, force: true });
+    }
+  });
+});
+
+describe('pinnedVersion', () => {
+  it('answers a spec that names a version', () => {
+    expect(pinnedVersion('@profullstack/crawlproof@0.2.0')).toBe('0.2.0');
+    expect(pinnedVersion('hqtui-demo@1.2.3')).toBe('1.2.3');
+  });
+
+  it('declines a tag or a range, so the registry is asked instead', () => {
+    expect(pinnedVersion('@profullstack/crawlproof@latest')).toBeNull();
+    expect(pinnedVersion('@profullstack/crawlproof@^0.1')).toBeNull();
+    expect(pinnedVersion('@profullstack/crawlproof')).toBeNull();
+  });
+});
+
+describe('registryLatest', () => {
+  it('reads the version npm prints', async () => {
+    expect(await registryLatest('pkg', fakeExec('0.2.0\n'))).toBe('0.2.0');
+  });
+
+  it('is null when npm fails, so an offline box is not told it is wrong', async () => {
+    expect(await registryLatest('pkg', fakeExec('', 1))).toBeNull();
+    expect(await registryLatest('pkg', fakeExec('not a version\n'))).toBeNull();
+  });
+});
+
+describe('wantedVersion', () => {
+  it('prefers the pin and never asks the registry for one', async () => {
+    const boom = (async () => {
+      throw new Error('should not be called');
+    }) as never;
+    expect(await wantedVersion('pkg@1.4.2', 'pkg', boom)).toBe('1.4.2');
+  });
+
+  it('asks the registry for a tag', async () => {
+    expect(await wantedVersion('pkg@latest', 'pkg', fakeExec('9.9.9\n'))).toBe('9.9.9');
+  });
+});
+
+describe('delivered', () => {
+  // The whole point: pnpm 11 exits 0 having installed the previous release.
+  it('rejects an install that left an older version behind', () => {
+    expect(delivered('0.1.0', '0.2.0')).toBe(false);
+  });
+
+  it('accepts the version that was asked for', () => {
+    expect(delivered('0.2.0', '0.2.0')).toBe(true);
+  });
+
+  it('accepts anything when the want could not be determined', () => {
+    // An unreachable registry must not make a working reinstall look broken.
+    expect(delivered('0.1.0', null)).toBe(true);
+    expect(delivered(null, null)).toBe(true);
+  });
+
+  it('rejects an install that produced nothing at all', () => {
+    expect(delivered(null, '0.2.0')).toBe(false);
+  });
+});
+
+describe('heldBackNote', () => {
+  it('names the version gap rather than saying it failed', () => {
+    const note = heldBackNote('pnpm', '0.1.0', '0.2.0');
+    expect(note).toContain('0.1.0');
+    expect(note).toContain('0.2.0');
+    expect(note).toContain('pnpm');
+  });
+});