diff --git a/.changeset/apimethods-batch-conformance-ratchet.md b/.changeset/apimethods-batch-conformance-ratchet.md
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+++ b/.changeset/apimethods-batch-conformance-ratchet.md
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+---
+---
+
+test(spec): ratchet the "single-record writes imply batch" invariant across every `*.object.ts` (#3026)
+
+Test-only — releases nothing. Adds the monorepo-wide scan that would have
+caught #3745 before it shipped: the eight objects that kept 405-ing `/batch`
+and the `*Many` routes after the #3391 P1 bulk gate became `bulk ∧ child`,
+because the sweep that added the `bulk` primitive was scoped to one package
+while the gap lived in three others.
diff --git a/packages/spec/src/data/api-methods-batch-conformance.test.ts b/packages/spec/src/data/api-methods-batch-conformance.test.ts
new file mode 100644
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+++ b/packages/spec/src/data/api-methods-batch-conformance.test.ts
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+// Copyright (c) 2026 ObjectStack. Licensed under the Apache-2.0 license.
+//
+// Conformance ratchet: a tightened `apiMethods` whitelist that grants
+// single-record writes must also grant the `bulk` primitive (#3026 follow-up).
+//
+// The #3391 P1 contract made the bulk gate `bulk ∧ derived(child)`: a batch
+// request is admitted only when the object grants the `bulk` PRIMITIVE and the
+// batched child operation is itself allowed. Before that, the `*Many` routes
+// checked only the child verb, so a boilerplate CRUD-five whitelist batched
+// fine. Every object carrying an explicit whitelist therefore needed `bulk`
+// added — and the sweep that did it was scoped to `platform-objects`, so eight
+// objects in `plugin-security`, `plugin-approvals` and `metadata-core` silently
+// kept 405-ing `/batch`, `createMany`, `updateMany` and `deleteMany` while
+// their single-record writes stayed wide open (fixed in #3745).
+//
+// The bug was not a wrong judgement — it was an audit whose SCOPE was a package
+// name while the gap lived in packages nobody thought to open. This test
+// replaces that manual sweep with a scan of every `*.object.ts` in the
+// monorepo, so a new declaration anywhere is covered by construction. Scanning
+// source (rather than importing the packages) keeps the check next to the
+// derivation table without inverting the spec → * dependency direction — the
+// same technique as `system/constants/platform-object-names.test.ts`.
+//
+// If this fails, pick one deliberately:
+//   - the object should batch  → add `'bulk'` to its `apiMethods`;
+//   - it genuinely must not    → register it in SINGLE_RECORD_WRITE_ONLY below
+//                                with the reason, so the choice is on the record.
+
+import { describe, it, expect } from 'vitest';
+import { readFileSync, readdirSync, statSync } from 'node:fs';
+import { dirname, join, resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
+import { API_PRIMITIVES } from './api-derivation';
+
+const HERE = dirname(fileURLToPath(import.meta.url));
+/** …/packages/spec/src/data → repo root */
+const REPO_ROOT = resolve(HERE, '../../../..');
+const PACKAGES_DIR = join(REPO_ROOT, 'packages');
+
+/** The single-record write primitives whose batch shape `bulk` unlocks. */
+const WRITE_PRIMITIVES = ['create', 'update', 'delete'] as const;
+
+/**
+ * Objects that deliberately expose single-record writes but NO batch route,
+ * keyed by object name with the reason. Empty today: every tightened whitelist
+ * in the monorepo either grants `bulk` or grants no write verb at all.
+ *
+ * Adding an entry is a real decision — batch denial is invisible until a user
+ * multi-selects rows and `data-objectstack` rethrows the 405 without falling
+ * back to per-row writes. Write down why the object is worth that.
+ */
+const SINGLE_RECORD_WRITE_ONLY: Record<string, string> = {};
+
+/** Every `*.object.ts` under `packages/`, skipping build output and deps. */
+function walkObjectFiles(dir: string, out: string[] = []): string[] {
+  let entries: string[];
+  try {
+    entries = readdirSync(dir);
+  } catch {
+    return out;
+  }
+  for (const entry of entries) {
+    if (entry === 'node_modules' || entry === 'dist' || entry.startsWith('.')) continue;
+    const full = join(dir, entry);
+    let isDir: boolean;
+    try {
+      isDir = statSync(full).isDirectory();
+    } catch {
+      continue;
+    }
+    if (isDir) walkObjectFiles(full, out);
+    else if (entry.endsWith('.object.ts')) out.push(full);
+  }
+  return out;
+}
+
+/** The object name declared by `ObjectSchema.create({ name: '…' })`, if any. */
+function declaredObjectName(source: string): string | undefined {
+  return source.match(/ObjectSchema\.create\(\{[\s\S]{0,600}?name:\s*'([a-z0-9_]+)'/)?.[1];
+}
+
+interface Whitelist {
+  object: string;
+  file: string;
+  methods: string[];
+}
+
+/**
+ * Every authored `apiMethods: [...]` array literal under `packages/`. Legacy /
+ * unknown strings are kept as authored — the resolver ignores them, and this
+ * check only reasons about primitives.
+ */
+function collectWhitelists(): Whitelist[] {
+  const out: Whitelist[] = [];
+  for (const file of walkObjectFiles(PACKAGES_DIR)) {
+    const source = readFileSync(file, 'utf8');
+    const object = declaredObjectName(source) ?? '(unnamed)';
+    for (const match of source.matchAll(/apiMethods:\s*\[([^\]]*)\]/g)) {
+      out.push({
+        object,
+        file: file.slice(REPO_ROOT.length + 1),
+        methods: [...match[1].matchAll(/'([a-z]+)'/g)].map((m) => m[1]),
+      });
+    }
+  }
+  return out;
+}
+
+const WHITELISTS = collectWhitelists();
+
+describe('apiMethods conformance — single-record writes imply batch (#3026)', () => {
+  it('scans a plausible number of declarations (guards a silently empty sweep)', () => {
+    // A scan that matches nothing passes every assertion below vacuously — the
+    // exact failure mode this file exists to prevent. Pin a floor instead.
+    expect(WHITELISTS.length).toBeGreaterThan(40);
+  });
+
+  it('only authors the six primitives (legacy verbs are derived, never declared)', () => {
+    // Since the #3543 enum shrink a legacy verb in a whitelist is stripped at
+    // parse and ignored by the resolver, so declaring one is silently dead
+    // metadata — catch it at the source instead.
+    const primitives = new Set<string>(API_PRIMITIVES);
+    const offenders = WHITELISTS.flatMap(({ object, file, methods }) =>
+      methods.filter((m) => !primitives.has(m)).map((m) => `${object} declares '${m}' (${file})`),
+    );
+    expect(offenders).toEqual([]);
+  });
+
+  it('grants bulk wherever it grants create / update / delete', () => {
+    const offenders = WHITELISTS.filter(({ object, methods }) => {
+      if (SINGLE_RECORD_WRITE_ONLY[object] !== undefined) return false;
+      const grantsWrite = WRITE_PRIMITIVES.some((verb) => methods.includes(verb));
+      return grantsWrite && !methods.includes('bulk');
+    }).map(
+      ({ object, file, methods }) =>
+        `${object}: [${methods.join(', ')}] grants single-record writes but not 'bulk' — ` +
+        `/batch and the *Many routes will 405 (${file})`,
+    );
+    expect(offenders).toEqual([]);
+  });
+
+  it('keeps the exemption list free of stale entries', () => {
+    // An exemption that no longer describes a real single-record-write-only
+    // object reads as a documented decision while documenting nothing.
+    const stale = Object.keys(SINGLE_RECORD_WRITE_ONLY).filter((object) => {
+      const declared = WHITELISTS.filter((w) => w.object === object);
+      if (declared.length === 0) return true;
+      return declared.every(
+        (w) => w.methods.includes('bulk') || !WRITE_PRIMITIVES.some((v) => w.methods.includes(v)),
+      );
+    });
+    expect(stale).toEqual([]);
+  });
+});