diff --git a/packages/nopy/cubes/apt/all/manifest.mjs b/packages/nopy/cubes/apt/all/manifest.mjs
index 2abd002..fe52f43 100644
--- a/packages/nopy/cubes/apt/all/manifest.mjs
+++ b/packages/nopy/cubes/apt/all/manifest.mjs
@@ -1,6 +1,6 @@
 import { cubes } from '@bitsquare/nopy';
 
 export default cubes.Manifest({
-  name: '[apt-all] Test dependencies',
-  dependencies: () => ['apt/more'],
+  name: '[test:apt-all] Test dependencies',
+  dependencies: () => ['test:apt-more'],
 });
diff --git a/packages/nopy/cubes/apt/essentials/manifest.mjs b/packages/nopy/cubes/apt/essentials/manifest.mjs
index fef6d35..026b2ae 100644
--- a/packages/nopy/cubes/apt/essentials/manifest.mjs
+++ b/packages/nopy/cubes/apt/essentials/manifest.mjs
@@ -2,7 +2,7 @@ import { cubes } from '@bitsquare/nopy';
 import { z } from 'zod';
 
 export default cubes.Manifest({
-  name: '[apt:essentials] Install essential packages',
+  name: '[test:apt-essentials] Install essential packages',
   dependencies: () => [],
   schema: z.object({
     UPDATE: z.boolean().default(false),
diff --git a/packages/nopy/cubes/apt/more/manifest.mjs b/packages/nopy/cubes/apt/more/manifest.mjs
index c96956d..70bf794 100644
--- a/packages/nopy/cubes/apt/more/manifest.mjs
+++ b/packages/nopy/cubes/apt/more/manifest.mjs
@@ -1,6 +1,6 @@
 import { cubes } from '@bitsquare/nopy';
 
 export default cubes.Manifest({
-  name: '[apt-more] Test dependencies',
-  dependencies: () => [['apt/essentials']],
+  name: '[test:apt-more] Test dependencies',
+  dependencies: () => [['test:apt-essentials']],
 });
diff --git a/packages/nopy/docs/CUBE-PACKAGES.md b/packages/nopy/docs/CUBE-PACKAGES.md
index 4bbdb60..16fe2f8 100644
--- a/packages/nopy/docs/CUBE-PACKAGES.md
+++ b/packages/nopy/docs/CUBE-PACKAGES.md
@@ -1,6 +1,6 @@
 # Cube bundles as npm packages
 
-Status: **plan, not a record.** Nothing here is implemented yet.
+Status: **Phase 0 has landed; Phases 1–6 are still a plan, not a record.**
 
 Distributing cubes as npm packages so a project can `pnpm add @acme/cubes-net`
 and have its cubes show up in `nopy` alongside local ones.
@@ -58,39 +58,60 @@ What blocks a clean story:
    `isSymbolicLink()`, not `isDirectory()` — the scan would skip every package.
    Package roots must be resolved explicitly.
 
-## Phase 0 — fixes that land first
+## Phase 0 — fixes that land first — **done**
 
 Independent of packaging, and the duplicate-id work depends on them.
 
-**0.1 `scanDirectory` drops subtrees on duplicates.** `loader.ts:84-87` pushes
-the error and `return`s, which exits before the recursive descent at line 100.
-Cubes nested below a duplicate never get scanned, so the error report is
-incomplete: you fix one collision, re-run, find the next. Should record the
-duplicate and keep descending.
+**0.1 `scanDirectory` drops subtrees on duplicates.** `loader.ts:84-87` pushed
+the error and `return`ed, which exited before the recursive descent at line 100.
+Cubes nested below a duplicate never got scanned, so the error report was
+incomplete: you fix one collision, re-run, find the next.
 
-**0.2 Duplicate detection is order-dependent.** `loadCubes()` runs
-`Promise.all` over folders into a shared `cubes` object, so which source is
-"first" and which is "the duplicate" varies run to run. Restructure: the scan
-emits a flat list of candidates, then a single grouping pass builds `cubes` and
-the error list. Makes the hard-error path deterministic, which the tests need.
+**0.2 Duplicate detection is order-dependent.** `loadCubes()` ran `Promise.all`
+over folders into a shared `cubes` object, so which source was "first" and which
+was "the duplicate" varied run to run.
+
+Both are one restructure. Scanning and id resolution are now separate passes:
+each root fills its own `ScanResult`, the lists are concatenated in root order
+(`Promise.all` preserves input order regardless of completion order), and a
+grouping pass builds `cubes` and the errors. `scanDirectory` no longer decides
+anything about ids, so it always descends. Directory entries are sorted, and a
+directory reachable from two roots is deduped by path — one cube seen twice is
+not a collision, which it used to be reported as.
 
 **0.3 `apt:essentials` is already declared twice.** `cubes/apt/essentials`
-declares it via `id`; `packages/nopy/cubes/apt/essentials` declares it via the
+declares it via `id`; `packages/nopy/cubes/apt/essentials` declared it via an
 `[apt:essentials]` prefix in `name`. `cubeDirs` merges root-first, so running
-`nopy` from `packages/nopy` already collects both and errors. Rename the
-`packages/nopy/cubes` fixtures (`[test:apt-essentials]`, `[test:apt-all]`,
-`[test:apt-more]`) — they are dev fixtures, not real cubes, and the migration in
-Phase 5 makes the collision permanent otherwise.
+`nopy` from `packages/nopy` collected both and aborted. Confirmed against the
+real trees before the rename:
+
+```
+Duplicate cube id 'apt:essentials' from 2 sources:
+  /…/ansiblingz/cubes/apt/essentials
+  /…/ansiblingz/packages/nopy/cubes/apt/essentials
+Rename one of them, or remove a source from .nopyrc.json.
+```
+
+The three `packages/nopy/cubes` fixtures are now `[test:apt-essentials]`,
+`[test:apt-all]` and `[test:apt-more]`; all 25 cubes load with no errors. Their
+`dependencies` were stale too — they named `apt/more` and `apt/essentials`,
+which are not ids anything declares — so they now point at the renamed ids.
 
 **0.4 `coerceValue` breaks if zod is ever duplicated.** `nopy.prompts.ts:147-154`
-discriminates with `instanceof z.ZodDefault`, `z.ZodBoolean`, `z.ZodNumber` and
+discriminated with `instanceof z.ZodDefault`, `z.ZodBoolean`, `z.ZodNumber` and
 friends — checks against the *running CLI's* zod instance. The moment a bundle
 resolves its own copy of zod (entirely possible once manifests arrive from
 `node_modules`; see Phase 4), every check returns false and `coerceValue` falls
 through to the raw string, silently. Booleans stop being booleans.
 
-Rewrite against the string discriminant, which is instance-agnostic. Verified on
-the installed zod 4.4.3:
+`defaultValueOf` in `cubes/types.ts` had the same breakage, reached whenever a
+schema has one field without a `.default()` — `getDefaults()` tries
+`safeParse({})` first, which is instance-agnostic, and only then drops to the
+per-field read.
+
+Both now discriminate on `def.type`, a plain string that holds across instances,
+via two exported helpers (`zodKind`, `zodInner`). Verified on the installed zod
+4.4.3:
 
 ```
 z.boolean().default(false).def.type        → 'default'
@@ -98,8 +119,13 @@ z.boolean().default(false).def.innerType   → { def: { type: 'boolean' } }
 z.number().def.type                        → 'number'
 ```
 
-Do this before anything else in Phase 4 lands, and it stops being a footgun for
-the local `cubes/` tree too.
+`tests/helpers/foreign-zod.ts` rebuilds a schema as plain objects carrying zod's
+`def` but not its prototype — structurally what a second copy of zod produces,
+and `instanceof`-blind, so neither call site can regress.
+
+Worth noting for Phase 4: zod 4 exposes `def.defaultValue` as a getter that
+already invokes a lazily declared default, so the `typeof === 'function'` branch
+in `defaultValueOf` is now dead. It is kept as insurance against that changing.
 
 ## Phase 1 — the bundle contract
 
@@ -376,6 +402,18 @@ With the split, the hook is a convenience rather than load-bearing: bundles
 resolve `@bitsquare/nopy-cube` through their own `node_modules` and never reach
 it.
 
+**The gotcha is bigger than CLAUDE.md says: it is two specifiers, not one.**
+Measured by linking `@bitsquare/nopy` into the root `node_modules` and loading
+the real tree — every manifest then failed on `Cannot find package 'zod'`
+instead. Manifests import `z` directly to build their schema, and pnpm's
+isolated layout puts zod under `packages/nopy/node_modules`, not the root. A
+hook that only covers `@bitsquare/nopy` moves the error rather than fixing it,
+so it has to fall back for `zod` too. With both linked, all 25 cubes load.
+
+Falling back for `zod` hands local cubes the *CLI's* zod instance, so no
+duplication arises there. Bundles are the case that duplicates it, and Phase 0.4
+is what makes that safe.
+
 New `packages/nopy/src/nopy.resolve-hook.mjs`, registered once from `loadCubes()`
 before the first `import(manifestPath)`:
 
@@ -398,8 +436,9 @@ Constraints:
   structured-cloneable (a string URL is).
 - The `.mjs` must ship in `dist` and be listed in `files` — it already is, via
   the `dist` entry.
-- It resolves `@bitsquare/nopy`, not `@bitsquare/nopy-cube`. Bundles never depend
-  on the hook; only the in-repo `cubes/` tree and hand-written local cubes do.
+- It resolves `@bitsquare/nopy` and `zod`, not `@bitsquare/nopy-cube`. Bundles
+  never depend on the hook; only the in-repo `cubes/` tree and hand-written local
+  cubes do.
 
 ## Phase 5 — proof of concept: `packages/cubes-core`
 
diff --git a/packages/nopy/src/cubes/index.ts b/packages/nopy/src/cubes/index.ts
index 233074e..fd8bea9 100644
--- a/packages/nopy/src/cubes/index.ts
+++ b/packages/nopy/src/cubes/index.ts
@@ -31,6 +31,8 @@ export type {
 export {
   Cube,
   Manifest,
+  zodInner,
+  zodKind,
 } from './types.js';
 
 // Utilities
diff --git a/packages/nopy/src/cubes/loader.ts b/packages/nopy/src/cubes/loader.ts
index 6cc08d8..4306dad 100644
--- a/packages/nopy/src/cubes/loader.ts
+++ b/packages/nopy/src/cubes/loader.ts
@@ -50,68 +50,131 @@ function extractCubeId(manifest: Manifest): string | undefined {
   return match ? match[1] : undefined;
 }
 
+/** A cube found on disk, before ids have been checked against each other. */
+interface CubeCandidate {
+  id: string;
+  manifest: Manifest;
+  dir: string;
+  deployScript: string;
+}
+
+/** What one root directory contributed. */
+interface ScanResult {
+  candidates: CubeCandidate[];
+  errors: string[];
+}
+
 /**
- * Loads all cubes from discovered cube directories.
+ * Walks one root, collecting every cube below it.
+ *
+ * Deliberately does not decide anything about ids: a duplicate is only visible
+ * once every root has been walked, and stopping the descent here would hide
+ * whatever sits below the offending directory.
  */
-export async function loadCubes(): Promise<LoadResult> {
-  const cubesFolders = findCubeDirectories();
-  const cubes: Record<string, Cube> = {};
-  const errors: string[] = [];
+async function scanDirectory(currentDir: string, result: ScanResult): Promise<void> {
+  const entries = (await fs.readdir(currentDir, { withFileTypes: true })).sort((a, b) =>
+    a.name.localeCompare(b.name)
+  );
 
-  async function scanDirectory(currentDir: string, baseDir: string): Promise<void> {
-    const entries = await fs.readdir(currentDir, { withFileTypes: true });
+  const files = entries.filter((e) => e.isFile());
+  const manifestFile = files.find(
+    (f) => f.name === 'manifest.mjs' || f.name.endsWith('.manifest.mjs')
+  );
+  const deployFile = files.find((f) => f.name === 'deploy.py' || f.name.endsWith('.deploy.py'));
 
-    const files = entries.filter((e) => e.isFile());
-    const manifestFile = files.find(
-      (f) => f.name === 'manifest.mjs' || f.name.endsWith('.manifest.mjs')
-    );
-    const deployFile = files.find((f) => f.name === 'deploy.py' || f.name.endsWith('.deploy.py'));
+  if (manifestFile && deployFile) {
+    const manifestPath = path.join(currentDir, manifestFile.name);
 
-    if (manifestFile && deployFile) {
-      const cubePath = currentDir;
-      const manifestPath = path.join(cubePath, manifestFile.name);
+    try {
+      const manifest = (await import(manifestPath)).default as Manifest;
 
-      try {
-        const manifest = (await import(manifestPath)).default as Manifest;
+      if (!manifest || typeof manifest !== 'object') {
+        result.errors.push(`Invalid manifest export in ${manifestPath}`);
+      } else if (!manifest.name) {
+        result.errors.push(`Invalid manifest format in ${manifestPath}: missing 'name'`);
+      } else {
+        const cubeId = extractCubeId(manifest) || path.basename(currentDir);
 
-        if (!manifest || typeof manifest !== 'object') {
-          errors.push(`Invalid manifest export in ${manifestPath}`);
-        } else if (!manifest.name) {
-          errors.push(`Invalid manifest format in ${manifestPath}: missing 'name'`);
-        } else {
-          const cubeId = extractCubeId(manifest) || path.basename(cubePath);
+        // Ensure basic properties
+        manifest.id = cubeId;
+        manifest.schema = manifest.schema ?? z.object({});
 
-          if (cubes[cubeId]) {
-            errors.push(`Duplicate cube id '${cubeId}'`);
-            return;
-          }
-
-          // Ensure basic properties
-          manifest.id = cubeId;
-          manifest.schema = manifest.schema ?? z.object({});
-
-          cubes[cubeId] = new Cube(manifest, cubePath, deployFile.name);
-        }
-      } catch (err) {
-        errors.push(`Failed to load manifest ${manifestPath}: ${err}`);
-      }
-    }
-
-    for (const entry of entries) {
-      if (entry.isDirectory() && !entry.name.startsWith('.') && entry.name !== 'node_modules') {
-        await scanDirectory(path.join(currentDir, entry.name), baseDir);
+        result.candidates.push({
+          id: cubeId,
+          manifest,
+          dir: currentDir,
+          deployScript: deployFile.name,
+        });
       }
+    } catch (err) {
+      result.errors.push(`Failed to load manifest ${manifestPath}: ${err}`);
     }
   }
 
-  await Promise.all(
+  for (const entry of entries) {
+    if (entry.isDirectory() && !entry.name.startsWith('.') && entry.name !== 'node_modules') {
+      await scanDirectory(path.join(currentDir, entry.name), result);
+    }
+  }
+}
+
+/** The message a duplicate id produces. Aborts the run — see `nopy.main.ts`. */
+function duplicateError(id: string, group: CubeCandidate[]): string {
+  const where = group.map((c) => `  ${c.dir}`).join('\n');
+  return (
+    `Duplicate cube id '${id}' from ${group.length} sources:\n${where}\n` +
+    `Rename one of them, or remove a source from .nopyrc.json.`
+  );
+}
+
+/**
+ * Loads all cubes from discovered cube directories.
+ *
+ * Scanning and id resolution are separate passes on purpose. Each root
+ * contributes its own candidate list, and those lists are concatenated in
+ * root order rather than in whichever order the concurrent scans happened to
+ * finish — so which cube is reported as "the duplicate" is the same on every
+ * run, which is what makes the hard error testable.
+ */
+export async function loadCubes(): Promise<LoadResult> {
+  const cubesFolders = findCubeDirectories();
+
+  const scans = await Promise.all(
     cubesFolders.map(async (folder) => {
+      const result: ScanResult = { candidates: [], errors: [] };
       if (fs.existsSync(folder)) {
-        await scanDirectory(folder, folder);
+        await scanDirectory(folder, result);
       }
+      return result;
     })
   );
 
+  // Promise.all preserves input order regardless of completion order.
+  const errors = scans.flatMap((scan) => scan.errors);
+
+  // One directory reachable from two roots (a `cubeDirs` entry nested under a
+  // `.npcubes` marker, say) is one cube seen twice, not a collision.
+  const seenDirs = new Set<string>();
+  const byId = new Map<string, CubeCandidate[]>();
+
+  for (const candidate of scans.flatMap((scan) => scan.candidates)) {
+    if (seenDirs.has(candidate.dir)) continue;
+    seenDirs.add(candidate.dir);
+
+    const group = byId.get(candidate.id);
+    if (group) group.push(candidate);
+    else byId.set(candidate.id, [candidate]);
+  }
+
+  const cubes: Record<string, Cube> = {};
+  for (const [id, group] of byId) {
+    if (group.length > 1) errors.push(duplicateError(id, group));
+    // The map is still populated for the callers that only report; a duplicate
+    // is fatal, so which candidate landed here never reaches a deploy.
+    const [first] = group;
+    cubes[id] = new Cube(first.manifest, first.dir, first.deployScript);
+  }
+
   return { cubes, errors };
 }
 
diff --git a/packages/nopy/src/cubes/types.ts b/packages/nopy/src/cubes/types.ts
index 007dbc6..4427e07 100644
--- a/packages/nopy/src/cubes/types.ts
+++ b/packages/nopy/src/cubes/types.ts
@@ -82,6 +82,28 @@ export namespace Manifest {
   }
 }
 
+/**
+ * zod's runtime discriminant for a schema node, as a plain string.
+ *
+ * `instanceof z.ZodDefault` compares against the *running* copy of zod. A cube
+ * manifest is free to build its schema with a different copy — its own
+ * dependency, or one shipped inside a bundle — and then every `instanceof`
+ * quietly returns false and the caller falls through to a wrong answer instead
+ * of failing. `def.type` holds across instances, so nothing here may go back to
+ * `instanceof`.
+ */
+export function zodKind(zodType: unknown): string {
+  return (zodType as { def: { type: string } }).def.type;
+}
+
+/**
+ * The type a wrapper wraps — `.default()`, `.optional()`, `.nullable()`.
+ * Only call this for a node whose {@link zodKind} is one of those.
+ */
+export function zodInner(zodType: unknown): z.ZodType {
+  return (zodType as { def: { innerType: z.ZodType } }).def.innerType;
+}
+
 /**
  * Reads the `.default()` off a schema field, unwrapping the wrappers that may
  * sit above it (`.default().optional()`, `.default().nullable()`).
@@ -90,16 +112,32 @@ export namespace Manifest {
  * `requiredKeys()` recognises a field the user has to supply.
  */
 function defaultValueOf(zodType: z.ZodType): unknown {
-  if (zodType instanceof z.ZodDefault) {
-    const { defaultValue } = zodType._def as { defaultValue: unknown };
+  const kind = zodKind(zodType);
+  if (kind === 'default') {
+    // zod 4 exposes `defaultValue` as a getter that already invokes a lazily
+    // declared default; the function branch is insurance against that changing.
+    const { defaultValue } = (zodType as unknown as { def: { defaultValue: unknown } }).def;
     return typeof defaultValue === 'function' ? defaultValue() : defaultValue;
   }
-  if (zodType instanceof z.ZodOptional || zodType instanceof z.ZodNullable) {
-    return defaultValueOf(zodType._def.innerType as z.ZodType);
+  if (kind === 'optional' || kind === 'nullable') {
+    return defaultValueOf(zodInner(zodType));
   }
   return undefined;
 }
 
+/**
+ * Where a cube was discovered.
+ *
+ * Worth carrying because a cube's own directory does not say how it got into
+ * the run: `/…/node_modules/@acme/cubes-net/cubes/x` could equally have come
+ * from a `cubeDirs` entry pointing straight at it.
+ */
+export type CubeSource =
+  /** Found under a `cubeDirs` entry or a `.npcubes` marker, at `dir`. */
+  | { type: 'dir'; dir: string }
+  /** Contributed by a package named in `cubePackages`. */
+  | { type: 'package'; packageName: string; dir: string };
+
 /**
  * A fully loaded cube with its filesystem location and runtime state
  */
@@ -107,7 +145,9 @@ export class Cube<Schema extends AnyObjectSchema = AnyObjectSchema> {
   constructor(
     public readonly manifest: Manifest<Schema>,
     public readonly dir: string,
-    public readonly deployScript: string
+    public readonly deployScript: string,
+    /** Defaults to the cube's own directory, for cubes built by hand. */
+    public readonly source: CubeSource = { type: 'dir', dir }
   ) {}
 
   get id(): string {
diff --git a/packages/nopy/src/nopy.config.ts b/packages/nopy/src/nopy.config.ts
index d169ece..16a13b5 100644
--- a/packages/nopy/src/nopy.config.ts
+++ b/packages/nopy/src/nopy.config.ts
@@ -55,13 +55,41 @@ export type ResolutionConfig = {
 };
 
 /**
- * Raw config file structure (includes resolution)
+ * A cube package named in `cubePackages`, paired with where it was named.
+ *
+ * Node resolution has to start from the config file that asked for the package,
+ * not from `process.cwd()` — otherwise a package listed in `~/.nopyrc.json`
+ * only resolves in projects that happen to depend on it themselves. This is the
+ * same problem {@link PATH_PROPERTIES} solves for `cubeDirs`, except the answer
+ * is a reference to resolve later rather than a rewritten path.
  */
-export interface NopyConfigFile extends Partial<NopyConfig> {
+export interface CubePackageRef {
+  /** The package name as written in the config, e.g. `@acme/cubes-net`. */
+  spec: string;
+  /** Directory of the `.nopyrc.json` that named it. */
+  from: string;
+}
+
+/**
+ * Raw config file structure (includes resolution)
+ *
+ * Diverges from {@link NopyConfig} for `cubePackages`: a file lists plain
+ * package names, and loading turns each into a {@link CubePackageRef}.
+ */
+export interface NopyConfigFile extends Omit<Partial<NopyConfig>, 'cubePackages'> {
+  /** Cube packages to load, by package name */
+  cubePackages?: string[];
   /** Customize merge behavior for specific properties */
   resolution?: ResolutionConfig;
 }
 
+/**
+ * A config file whose paths have been resolved — what actually gets merged.
+ */
+type ResolvedConfigFile = Omit<NopyConfigFile, 'cubePackages'> & {
+  cubePackages?: CubePackageRef[];
+};
+
 /**
  * Nopy configuration file structure
  */
@@ -70,6 +98,8 @@ export interface NopyConfig {
   hosts: string[];
   /** Directories to search for cubes */
   cubeDirs: string[];
+  /** Installed packages to load cubes from */
+  cubePackages: CubePackageRef[];
   /** Global environment variables */
   env: TVariables;
   /** Logging configuration */
@@ -86,6 +116,7 @@ export interface NopyConfig {
 const DEFAULT_CONFIG: NopyConfig = {
   hosts: [],
   cubeDirs: [],
+  cubePackages: [],
   env: {},
 };
 
@@ -219,30 +250,33 @@ const PATH_PROPERTIES: (keyof NopyConfig)[] = ['cubeDirs'];
  * Resolves relative paths in a config file based on its location
  * Only resolves paths for properties that are known to contain filesystem paths
  */
-function resolveConfigPaths(config: NopyConfigFile, configPath: string): NopyConfigFile {
+function resolveConfigPaths(config: NopyConfigFile, configPath: string): ResolvedConfigFile {
   const configDir = path.dirname(configPath);
-  const resolved: NopyConfigFile = {};
+  const resolved: Record<string, unknown> = {};
 
   for (const [key, value] of Object.entries(config)) {
     if (key === 'resolution') {
       // Don't resolve the resolution config itself
       resolved[key] = value as ResolutionConfig;
+    } else if (key === 'cubePackages') {
+      // Not a path — a package name, tagged with where to resolve it from.
+      resolved[key] = (value as string[]).map((spec) => ({ spec, from: configDir }));
     } else if (PATH_PROPERTIES.includes(key as keyof NopyConfig)) {
       // Only resolve paths for known path properties
-      resolved[key as keyof NopyConfigFile] = resolveRelativePaths(value, configDir) as any;
+      resolved[key] = resolveRelativePaths(value, configDir);
     } else {
       // Copy other properties as-is (including hosts)
-      resolved[key as keyof NopyConfigFile] = value as any;
+      resolved[key] = value;
     }
   }
 
-  return resolved;
+  return resolved as ResolvedConfigFile;
 }
 
 /**
  * Merges a child config into a parent config
  */
-function mergeConfigs(parent: NopyConfig, childFile: NopyConfigFile): NopyConfig {
+function mergeConfigs(parent: NopyConfig, childFile: ResolvedConfigFile): NopyConfig {
   const resolution = childFile.resolution || {};
   const result: Record<string, unknown> = { ...parent };
 
diff --git a/packages/nopy/src/nopy.prompts.ts b/packages/nopy/src/nopy.prompts.ts
index b473acd..786e861 100644
--- a/packages/nopy/src/nopy.prompts.ts
+++ b/packages/nopy/src/nopy.prompts.ts
@@ -6,8 +6,8 @@
 import Enquirer from 'enquirer';
 import fuzzy from 'fuzzy';
 import inquirer from 'inquirer';
-import { z } from 'zod';
-import type { AnyObjectSchema, Cube } from './cubes/index.js';
+import type { z } from 'zod';
+import { type AnyObjectSchema, type Cube, zodInner, zodKind } from './cubes/index.js';
 import type { Variables } from './nopy.common.js';
 
 interface CubeChoice {
@@ -142,20 +142,32 @@ export async function HostSelection(hosts: string[]): Promise<string> {
   return selectedHost.customHost ?? selectedHost.host;
 }
 
+/**
+ * Turns a form answer — always a string — back into what the schema declares.
+ *
+ * Discriminates on {@link zodKind} rather than `instanceof`: the schema may
+ * have been built by a copy of zod that is not the one this file imported, and
+ * `instanceof` would then fail open and leave every value a string.
+ */
 function coerceValue(value: unknown, zodType: z.core.$ZodType): unknown {
   if (typeof value !== 'string') return value;
-  if (zodType instanceof z.ZodDefault) return coerceValue(value, zodType._def.innerType);
-  if (zodType instanceof z.ZodOptional) return coerceValue(value, zodType._def.innerType);
-  if (zodType instanceof z.ZodNullable) {
-    if (value === 'null' || value === '') return null;
-    return coerceValue(value, zodType._def.innerType);
+
+  switch (zodKind(zodType)) {
+    case 'default':
+    case 'optional':
+      return coerceValue(value, zodInner(zodType));
+    case 'nullable':
+      if (value === 'null' || value === '') return null;
+      return coerceValue(value, zodInner(zodType));
+    case 'boolean':
+      return value === 'true' || value === 'yes' || value === '1';
+    case 'number': {
+      const num = Number(value);
+      return Number.isNaN(num) ? value : num;
+    }
+    default:
+      return value;
   }
-  if (zodType instanceof z.ZodBoolean) return value === 'true' || value === 'yes' || value === '1';
-  if (zodType instanceof z.ZodNumber) {
-    const num = Number(value);
-    return Number.isNaN(num) ? value : num;
-  }
-  return value;
 }
 
 interface FormChoice {
diff --git a/packages/nopy/tests/cubes.loader.edge.test.ts b/packages/nopy/tests/cubes.loader.edge.test.ts
index dbefaeb..0c7bb6d 100644
--- a/packages/nopy/tests/cubes.loader.edge.test.ts
+++ b/packages/nopy/tests/cubes.loader.edge.test.ts
@@ -136,14 +136,63 @@ describe('loader edge cases', () => {
       expect(errors[0]).toMatch(/Failed to load manifest/);
     });
 
-    it('reports duplicate cube ids', async () => {
+    it('reports duplicate cube ids, naming every directory that claims one', async () => {
       cube('first', 'export default { id: "dup", name: "First" }');
       cube('second', 'export default { id: "dup", name: "Second" }');
 
       const { cubes, errors } = await loadCubes();
 
       expect(Object.keys(cubes)).toEqual(['dup']);
-      expect(errors[0]).toMatch(/Duplicate cube id 'dup'/);
+      expect(errors).toHaveLength(1);
+      expect(errors[0]).toMatch(/Duplicate cube id 'dup' from 2 sources/);
+      expect(errors[0]).toContain(path.join(tmpDir, 'first'));
+      expect(errors[0]).toContain(path.join(tmpDir, 'second'));
+    });
+
+    it('keeps scanning below a duplicate instead of dropping the subtree', async () => {
+      cube('first', 'export default { id: "dup", name: "First" }');
+      cube('second', 'export default { id: "dup", name: "Second" }');
+      cube('second/inner', 'export default { id: "buried", name: "Buried" }');
+
+      const { cubes, errors } = await loadCubes();
+
+      expect(cubes.buried).toBeDefined();
+      expect(errors).toHaveLength(1);
+    });
+
+    it('reports the same duplicate whichever root is scanned first', async () => {
+      cube('a/one', 'export default { id: "dup", name: "One" }');
+      cube('b/two', 'export default { id: "dup", name: "Two" }');
+      const roots = [path.join(tmpDir, 'a'), path.join(tmpDir, 'b')];
+
+      fs.writeFileSync(path.join(tmpDir, '.nopyrc.json'), JSON.stringify({ cubeDirs: roots }));
+      const forwards = await loadCubes();
+
+      fs.writeFileSync(
+        path.join(tmpDir, '.nopyrc.json'),
+        JSON.stringify({ cubeDirs: [...roots].reverse() })
+      );
+      const backwards = await loadCubes();
+
+      expect(forwards.errors[0]).toContain(path.join(tmpDir, 'a', 'one'));
+      expect(forwards.errors[0]).toContain(path.join(tmpDir, 'b', 'two'));
+      expect(backwards.errors).toHaveLength(1);
+      expect(new Set(backwards.errors[0].split('\n'))).toEqual(
+        new Set(forwards.errors[0].split('\n'))
+      );
+    });
+
+    it('does not call one directory a duplicate of itself when two roots reach it', async () => {
+      cube('nested/one', 'export default { id: "once", name: "Once" }');
+      fs.writeFileSync(
+        path.join(tmpDir, '.nopyrc.json'),
+        JSON.stringify({ cubeDirs: ['./', './nested'] })
+      );
+
+      const { cubes, errors } = await loadCubes();
+
+      expect(errors).toEqual([]);
+      expect(cubes.once).toBeDefined();
     });
 
     it('skips hidden and node_modules directories', async () => {
diff --git a/packages/nopy/tests/cubes.types.test.ts b/packages/nopy/tests/cubes.types.test.ts
index 420f193..2132ff1 100644
--- a/packages/nopy/tests/cubes.types.test.ts
+++ b/packages/nopy/tests/cubes.types.test.ts
@@ -6,6 +6,7 @@
 import { describe, expect, it } from 'vitest';
 import { z } from 'zod';
 import { Cube, Manifest } from '../src/cubes/types.js';
+import { foreignZodSchema } from './helpers/foreign-zod.js';
 
 const cube = (schema: z.ZodObject<any>) =>
   new Cube(Manifest.create({ id: 'c', name: 'C', schema }), '/cubes/c', 'deploy.py');
@@ -64,6 +65,22 @@ describe('Cube.getDefaults', () => {
   it('returns an empty object for an empty schema', () => {
     expect(cube(z.object({})).getDefaults()).toEqual({});
   });
+
+  it('reads defaults off a schema built by a different copy of zod', () => {
+    // The per-field fallback reads zod's internals directly. Under `instanceof`
+    // a foreign schema yields no defaults at all, without erroring.
+    const c = cube(
+      foreignZodSchema(
+        z.object({
+          REQUIRED: z.string(),
+          PRIORITY: z.number().default(10),
+          NESTED: z.number().default(2).optional(),
+        })
+      )
+    );
+
+    expect(c.getDefaults()).toEqual({ PRIORITY: 10, NESTED: 2 });
+  });
 });
 
 describe('Cube.requiredKeys', () => {
diff --git a/packages/nopy/tests/helpers/foreign-zod.ts b/packages/nopy/tests/helpers/foreign-zod.ts
new file mode 100644
index 0000000..9cb4504
--- /dev/null
+++ b/packages/nopy/tests/helpers/foreign-zod.ts
@@ -0,0 +1,29 @@
+/**
+ * A schema that behaves like zod's but does not share zod's prototypes.
+ *
+ * Once cubes arrive from `node_modules`, the schema a manifest builds may come
+ * from a *second* copy of zod — its own dependency, or one shipped inside a
+ * bundle. Such a schema is structurally identical and `instanceof` blind to it.
+ * Rebuilding the nodes as plain objects reproduces that from inside a single
+ * process, so anything that reads zod's internals stays pinned to `def.type`.
+ */
+
+import type { z } from 'zod';
+
+/** Strips the prototype off a schema node and everything it wraps. */
+function strip(node: unknown): unknown {
+  const def = { ...(node as { def: Record<string, unknown> }).def };
+  if (def.innerType) def.innerType = strip(def.innerType);
+  return { def };
+}
+
+export function foreignZodSchema<S extends z.ZodObject<any>>(schema: S): S {
+  return {
+    // Parsing is not what is under test — delegate it and keep the real
+    // behaviour, so only the introspection path sees the foreign nodes.
+    safeParse: (value: unknown) => schema.safeParse(value),
+    shape: Object.fromEntries(
+      Object.entries(schema.shape).map(([key, node]) => [key, strip(node)])
+    ),
+  } as unknown as S;
+}
diff --git a/packages/nopy/tests/prompts.test.ts b/packages/nopy/tests/prompts.test.ts
index 83bbfd5..158af63 100644
--- a/packages/nopy/tests/prompts.test.ts
+++ b/packages/nopy/tests/prompts.test.ts
@@ -46,6 +46,7 @@ import {
   PasswordSelection,
   VariableAssignment,
 } from '../src/nopy.prompts.js';
+import { foreignZodSchema } from './helpers/foreign-zod.js';
 
 /** Grabs the single question object passed to the last inquirer.prompt call. */
 const questions = () => inquirerPrompt.mock.calls.at(-1)?.[0] as Record<string, any>[];
@@ -310,13 +311,14 @@ describe('VariableAssignment', () => {
     const nullableSchema = z.object({
       maybe: z.number().nullable().default(1),
       opt: z.number().optional().default(2),
+      given: z.number().nullable().default(3),
     });
     const variables = new Variables();
-    formRun.mockResolvedValue({ maybe: 'null', opt: '7' });
+    formRun.mockResolvedValue({ maybe: 'null', opt: '7', given: '42' });
 
     await VariableAssignment(cube('svc', 'Service', nullableSchema), variables);
 
-    expect(variables.get('svc', 'prompts')).toEqual({ maybe: null, opt: 7 });
+    expect(variables.get('svc', 'prompts')).toEqual({ maybe: null, opt: 7, given: 42 });
   });
 
   it('treats an empty string as null for a nullable field', async () => {
@@ -356,4 +358,28 @@ describe('VariableAssignment', () => {
     ).resolves.toBeUndefined();
     expect(variables.get('svc', 'prompts')).toEqual({});
   });
+
+  it('coerces against a schema built by a different copy of zod', async () => {
+    // Guards the discriminant in `coerceValue`: under `instanceof` every check
+    // here returns false and the answers stay strings, silently.
+    const variables = new Variables();
+    formRun.mockResolvedValue({ port: '9090', enabled: 'true', maybe: '' });
+
+    await VariableAssignment(
+      cube(
+        'svc',
+        'Service',
+        foreignZodSchema(
+          z.object({
+            port: z.number().default(8080),
+            enabled: z.boolean().default(false),
+            maybe: z.number().nullable().default(1),
+          })
+        )
+      ),
+      variables
+    );
+
+    expect(variables.get('svc', 'prompts')).toEqual({ port: 9090, enabled: true, maybe: null });
+  });
 });