objectstack-ai
diff --git a/‎.changeset/18239-merge-objects-refusal.md‎
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diff --git a/‎packages/spec/src/compose-stacks-objects-shape-refusal.test.ts‎
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diff --git a/‎packages/spec/src/stack.zod.ts‎
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@@ -0,0 +1,25 @@
+---
+'@objectstack/spec': minor
+---
+
+fix(spec): `composeStacks` refuses a stack whose `objects` is not an array, with the ADR-0112 envelope
+
+**BREAKING** — `composeStacks`, a public root export, now refuses a class of input it used to crash on, skip in silence, or compose by accident.
+
+Step 2 of `composeStacks` (`mergeObjects`) iterated each input's `objects` with no shape guard. The strict `defineStack` parse already rejects a non-array `objects`, so the reachable population is an input that bypassed it — a hand-built stack object, or `defineStack(config, { strict: false })`. Measured before this change, composing a well-formed stack with such an input:
+
+| the second stack's `objects` | before | after |
+| :--- | :--- | :--- |
+| a map (`{ b_item: {…} }`) or a number | bare `TypeError: … is not iterable`, `code` and `status` both `undefined` | refused, `STACK_SCHEMA_INVALID`, `status: 422` |
+| `null`, `''`, `0`, `false` | composed, the stack's objects silently absent | refused, `STACK_SCHEMA_INVALID`, `status: 422` |
+| a `Set` of objects | composed as if it were an array | refused, `STACK_SCHEMA_INVALID`, `status: 422` |
+
+A composed artifact is complete or it is refused: skipping a stack's objects composes an artifact that silently lacks them, so no non-array `objects` is skipped. An absent `objects` (`undefined`) is not malformed and composes as before. The refusal carries the code the strict parse raises for the same authored mistake — one code for one defect, whichever door catches it — with the zod issue on `issues` (`path: ['objects']`, `expected: 'array'`) and a message naming the stack by manifest id and position. The map form is an authoring spelling `defineStack` normalizes before any check runs; a stack that reaches composition without passing through `defineStack` never had it normalized, and is refused like any other non-array.
+
+A non-object entry inside an array `objects` (`null`, a number) is skipped and reported once through the composer's malformed-collection warning, the shape step 3 gives a non-array collection; before, it raised a bare `TypeError` reading `name` off it. The artifact cross-reference pass skips such an entry too.
+
+No code is added to the ADR-0112 ledger and no export changes: `STACK_SCHEMA_INVALID` is already registered under `@objectstack/spec`, and the error class stays module-local.
+
+<!-- adr-0087: not-required (no-migration-prescription) Nothing authorable moves: no spec key, Zod schema, export, config field or stored metadata shape is added, removed, renamed or re-spelled. The strict defineStack parse already refused every input this refuses, so an authored stack that passed its schema composes exactly as before; what narrows is the runtime behaviour of composeStacks on inputs that bypassed that parse, and objectstack migrate meta has no document to rewrite for it. -->
+
+Clause-②: no (narrowing)
@@ -0,0 +1,152 @@
+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+
+/**
+ * `composeStacks` step 2 (`mergeObjects`) refuses a stack whose `objects` is
+ * not an array (#18239, ruling B).
+ *
+ * ## What was wrong
+ *
+ * `mergeObjects` iterated `stack.objects` with no shape guard. An input that
+ * bypassed the strict `defineStack` parse (a hand-built stack object, or
+ * `defineStack(config, { strict: false })`) reached it in one of three ways,
+ * none of them a refusal:
+ *
+ * - a truthy non-iterable (`{ … }`, a number) raised a bare `TypeError`
+ *   (`stack.objects is not iterable`) — `code` and `status` both `undefined`,
+ *   outside the ADR-0112 envelope every other refusal in the file carries;
+ * - a falsy non-array (`null`, `''`, `0`, `false`) hit `if (!stack.objects)
+ *   continue` and was skipped IN SILENCE — the composed artifact simply lacked
+ *   that stack's objects, and nothing said so;
+ * - a non-array iterable (a `Set` of objects) composed as if it were an array.
+ *
+ * ## What is pinned
+ *
+ * The ruling: 「A composed artifact is complete or it is refused」. So a
+ * non-array `objects` is REFUSED with the envelope the strict parse raises for
+ * the very same authored defect — `STACK_SCHEMA_INVALID`, `status: 422`, the
+ * zod issue on `issues` with its `path` naming `objects` — and never skipped.
+ * The code names the rule (the stack does not match its schema); the message
+ * header names the pass (`composeStacks`), the same split
+ * `STACK_CROSS_REFERENCE_INVALID` makes across its two raise sites.
+ *
+ * A non-object ENTRY inside a well-formed `objects` array follows step 3's
+ * shape instead: skipped, and reported through the shared malformed-collection
+ * warning — the entry carries no object for composition to merge.
+ *
+ * Every refusal has its CONTROL: the same composition with `objects` authored
+ * as an array is accepted, so no refusal can satisfy the assertions for the
+ * wrong reason.
+ */
+import { describe, it, expect, vi, afterEach } from 'vitest';
+import { composeStacks, defineStack, type ObjectStackDefinition } from './stack.zod';
+import { ERROR_CODE_LEDGER } from './api/error-code-ledger.zod';
+
+type Envelope = Error & {
+  code?: string;
+  status?: number;
+  issues?: ReadonlyArray<{ code?: string; path?: readonly PropertyKey[]; expected?: string }>;
+};
+
+/** The thrown value, or `null` when the composition is accepted. */
+function refusal(fn: () => unknown): Envelope | null {
+  try {
+    fn();
+    return null;
+  } catch (e) {
+    return e as Envelope;
+  }
+}
+
+const mf = (id: string) => ({ id, name: id.split('.').pop()!, version: '1.0.0', type: 'app' as const });
+
+const obj = (name: string) => ({ name, label: name, fields: { title: { type: 'text' as const } } });
+
+/** A stack object nobody parsed — the shape the card's reproduction used. */
+const handBuilt = (overrides: Record<string, unknown>) => overrides as unknown as ObjectStackDefinition;
+
+/** A stack through `defineStack`'s `strict: false` door, which skips the parse. */
+const unparsed = (overrides: Record<string, unknown>) =>
+  defineStack(overrides as never, { strict: false });
+
+const good = () => defineStack({ manifest: mf('com.example.a'), objects: [obj('a_item')] });
+
+const B1 = "'com.example.b' (stack #1)";
+
+afterEach(() => {
+  vi.restoreAllMocks();
+});
+
+/** Every refusal row: how the malformed `objects` reaches composition. */
+const rows: Array<{ label: string; build: () => ObjectStackDefinition }> = [
+  { label: 'a hand-built stack whose `objects` is a map', build: () => handBuilt({ manifest: mf('com.example.b'), objects: { b_item: obj('b_item') } }) },
+  { label: 'a hand-built stack whose `objects` is a number', build: () => handBuilt({ manifest: mf('com.example.b'), objects: 5 }) },
+  { label: 'a hand-built stack whose `objects` is a Set of objects', build: () => handBuilt({ manifest: mf('com.example.b'), objects: new Set([obj('b_item')]) }) },
+  { label: '`strict: false` with `objects: null`', build: () => unparsed({ manifest: mf('com.example.b'), objects: null }) },
+  { label: "`strict: false` with `objects: ''`", build: () => unparsed({ manifest: mf('com.example.b'), objects: '' }) },
+  { label: '`strict: false` with `objects: 0`', build: () => unparsed({ manifest: mf('com.example.b'), objects: 0 }) },
+  { label: '`strict: false` with `objects: false`', build: () => unparsed({ manifest: mf('com.example.b'), objects: false }) },
+];
+
+describe('#18239 — composeStacks refuses a non-array `objects` with an ADR-0112 envelope', () => {
+  for (const row of rows) {
+    describe(row.label, () => {
+      it('is refused with code STACK_SCHEMA_INVALID and status 422 — never a bare TypeError, never a skip', () => {
+        const refused = refusal(() => composeStacks([good(), row.build()]));
+        expect(refused).toBeInstanceOf(Error);
+        expect(refused?.code).toBe('STACK_SCHEMA_INVALID');
+        expect(refused?.status).toBe(422);
+      });
+
+      it('names the key and the stack — the zod issue rides `issues` with `path: [objects]`', () => {
+        const refused = refusal(() => composeStacks([good(), row.build()]));
+        expect(refused?.issues).toHaveLength(1);
+        expect(refused?.issues?.[0]?.path).toEqual(['objects']);
+        expect(refused?.issues?.[0]?.code).toBe('invalid_type');
+        expect(refused?.issues?.[0]?.expected).toBe('array');
+        expect(refused?.message.startsWith(`composeStacks validation failed: ${B1}`)).toBe(true);
+        expect(refused?.message).toContain("'objects'");
+      });
+
+      it('is refused whichever position the malformed stack holds', () => {
+        const refused = refusal(() => composeStacks([row.build(), good()]));
+        expect(refused?.code).toBe('STACK_SCHEMA_INVALID');
+        expect(refused?.status).toBe(422);
+      });
+    });
+  }
+
+  it('the control — the same composition with `objects` authored as an array is ACCEPTED', () => {
+    const composed = composeStacks([good(), unparsed({ manifest: mf('com.example.b'), objects: [obj('b_item')] })]);
+    expect(composed.objects?.map((o) => o.name)).toEqual(['a_item', 'b_item']);
+  });
+
+  it('an ABSENT `objects` is not a malformed one — still composed, still silent', () => {
+    const warn = vi.spyOn(console, 'warn').mockImplementation(() => {});
+    const composed = composeStacks([good(), unparsed({ manifest: mf('com.example.b') })]);
+    expect(composed.objects?.map((o) => o.name)).toEqual(['a_item']);
+    expect(warn.mock.calls.map((c) => String(c[0])).some((w) => w.includes("'objects'"))).toBe(false);
+  });
+
+  it('the strict door raises the SAME code for the same defect — one dialect for one authored mistake', () => {
+    // A number, not a map: the map form (`objects: { name: {…} }`) is a legal
+    // AUTHORING spelling that `defineStack` normalizes to the array before any
+    // check runs, so only a hand-built stack can carry a map into composition.
+    const refused = refusal(() => defineStack({ manifest: mf('com.example.b'), objects: 5 } as never));
+    expect(refused?.code).toBe('STACK_SCHEMA_INVALID');
+    expect(refused?.status).toBe(422);
+    expect(ERROR_CODE_LEDGER['@objectstack/spec']).toContain('STACK_SCHEMA_INVALID');
+  });
+
+  it('a non-object ENTRY inside an array `objects` is skipped and reported — step 3\'s shape', () => {
+    const warn = vi.spyOn(console, 'warn').mockImplementation(() => {});
+    const composed = composeStacks([
+      good(),
+      handBuilt({ manifest: mf('com.example.b'), objects: [null, obj('b_item'), 7] }),
+    ]);
+    expect(composed.objects?.map((o) => o.name)).toEqual(['a_item', 'b_item']);
+    const warnings = warn.mock.calls.map((c) => String(c[0]));
+    expect(
+      warnings.some((w) => w.includes('composeStacks') && w.includes("'objects'") && w.includes('not an object')),
+    ).toBe(true);
+  });
+});
@@ -1797,6 +1797,10 @@ function collectObjectNames(config: ObjectStackDefinition): Set<string> {
   const names = new Set<string>();
   if (config.objects) {
     for (const obj of config.objects) {
+      // [#18239] `composeStacks`' artifact pass reads its unparsed inputs through
+      // here, and `mergeObjects` skips a non-object entry rather than refusing
+      // it — so skip it here too instead of dereferencing it.
+      if (!isRecord(obj)) continue;
       names.add(obj.name);
     }
   }
@@ -3681,9 +3685,22 @@ const warnedMalformedCollectionKeys = new Set<string>();
  * `defineStack` path rejects the shape outright.
  * @internal
  */
-function warnMalformedCollectionKey(key: string): void {
-  if (warnedMalformedCollectionKeys.has(key)) return;
-  warnedMalformedCollectionKeys.add(key);
+function warnMalformedCollectionKey(key: string, shape: 'value' | 'entry' = 'value'): void {
+  // [#18239] `'entry'`: the collection IS an array but one of its entries is not
+  // an object (`mergeObjects`, where a non-array `objects` is refused instead).
+  // Deduplicated apart from the `'value'` notice, so neither silences the other.
+  const dedupKey = shape === 'value' ? key : `${key}[]`;
+  if (warnedMalformedCollectionKeys.has(dedupKey)) return;
+  warnedMalformedCollectionKeys.add(dedupKey);
+  if (shape === 'entry') {
+    console.warn(
+      `composeStacks: top-level key '${key}' is a collection but at least one stack carries an ` +
+        `entry in it that is not an object — that entry cannot be composed and was skipped. Author ` +
+        `every entry as an object, or run the stack through strict \`defineStack\` to have the ` +
+        `shape rejected where it is written.`,
+    );
+    return;
+  }
   console.warn(
     `composeStacks: top-level key '${key}' is a collection (concatenated across stacks) but at ` +
       `least one stack carries a non-array value for it — that value cannot be composed and was ` +
@@ -3994,8 +4011,46 @@ function mergeObjects(
   const collectionOwner = new Map<string, Map<string, number>>();
 
   for (const [i, stack] of stacks.entries()) {
-    if (!stack.objects) continue;
-    for (const obj of stack.objects) {
+    // [ADR-0112 · #18239] Shape guard, because composition accepts inputs the
+    // strict parse never saw (a hand-built stack, `strict: false`). A non-array
+    // `objects` is REFUSED, never skipped: skipping it composes an artifact that
+    // silently lacks this stack's objects — a composed artifact is complete or
+    // it is refused. `undefined` is the one non-array that is not malformed: the
+    // key is simply absent. The code is the strict parse's own
+    // (`STACK_SCHEMA_INVALID`) because the defect is the same authored mistake
+    // that door refuses; the header names this pass, the split
+    // {@link StackCrossReferenceError} makes across its two raise sites.
+    const declared: unknown = (stack as { objects?: unknown }).objects;
+    if (declared === undefined) continue;
+    if (!Array.isArray(declared)) {
+      const parsed = z.array(z.unknown()).safeParse(declared);
+      const issues = parsed.success
+        ? []
+        : parsed.error.issues.map((issue) => ({ ...issue, path: ['objects', ...issue.path] }));
+      const kind =
+        declared === null
+          ? 'null'
+          : typeof declared !== 'object'
+            ? `a ${typeof declared}`
+            : Object.getPrototypeOf(declared) === Object.prototype
+              ? 'an object'
+              : `a ${(declared as object).constructor?.name ?? 'non-plain'} object`;
+      throw new StackSchemaInvalidError(
+        `composeStacks validation failed: ${stackLabel(stack, i)} declares 'objects' as ${kind}, ` +
+          `not an array. Its objects cannot be composed, and skipping them would compose an artifact ` +
+          `that silently lacks them. Author 'objects' as an array (\`defineStack\` normalizes the map ` +
+          `form into one), or run the stack through strict \`defineStack\` to have the shape rejected ` +
+          `where it is written.`,
+        issues as z.core.$ZodIssue[],
+      );
+    }
+    for (const obj of declared as Obj[]) {
+      // A non-object ENTRY carries no object to merge — step 3's shape: skip it
+      // and say so once, never dereference it into a bare `TypeError`.
+      if (!isRecord(obj)) {
+        warnMalformedCollectionKey('objects', 'entry');
+        continue;
+      }
       const existing = map.get(obj.name);
       if (!existing) {
         map.set(obj.name, obj);