diff --git a/.changeset/config.json b/.changeset/config.json
index a970114509..f34c2fa1d9 100644
--- a/.changeset/config.json
+++ b/.changeset/config.json
@@ -21,6 +21,7 @@
       "@objectstack/metadata-core",
       "@objectstack/metadata-fs",
       "@objectstack/objectql",
+      "@objectstack/metadata-protocol",
       "@objectstack/observability",
       "@objectstack/formula",
       "@objectstack/lint",
diff --git a/.changeset/extract-metadata-protocol.md b/.changeset/extract-metadata-protocol.md
new file mode 100644
index 0000000000..97cc7e0ebd
--- /dev/null
+++ b/.changeset/extract-metadata-protocol.md
@@ -0,0 +1,16 @@
+---
+'@objectstack/objectql': minor
+'@objectstack/metadata-protocol': minor
+---
+
+Extract metadata management into `@objectstack/metadata-protocol` (ADR-0076)
+
+`protocol.ts` (the `ObjectStackProtocol` implementation — sys_metadata CRUD, draft/publish, locks, package ownership, diagnostics) plus its `sys-metadata-repository`, `metadata-diagnostics`, `seed-loader`, and `build-probes` helpers were metadata-domain code that lived inside `@objectstack/objectql` for historical reasons. They now live in a dedicated **`@objectstack/metadata-protocol`** package.
+
+The protocol no longer depends on the concrete `ObjectQL` class — it is typed against an injected `MetadataHostEngine` interface (the engine is still injected at runtime). Dependency direction is now one-way (`objectql → metadata-protocol`); there is no cycle.
+
+**Non-breaking**: `@objectstack/objectql` re-exports every previously public symbol (`ObjectStackProtocolImplementation`, `SysMetadataRepository`, `SysMetadataEngine`, `SeedLoaderService`, `runBuildProbes`, …), so existing imports keep working.
+
+This is Step 1 of ADR-0076. A later step turns the protocol into a capability plugin so `objectql` itself stops depending on it (making the engine lean by construction).
+
+Also adds a lean **`@objectstack/objectql/core`** entry — the engine/registry/hooks/validation surface only, with no kernel plugin or metadata protocol — so a thin embedder can import just the engine and never pull `@objectstack/metadata-protocol` into its bundle. A boundary ratchet test guards the entry.
diff --git a/packages/metadata-protocol/README.md b/packages/metadata-protocol/README.md
new file mode 100644
index 0000000000..5715bc028b
--- /dev/null
+++ b/packages/metadata-protocol/README.md
@@ -0,0 +1,7 @@
+# @objectstack/metadata-protocol
+
+The ObjectStack metadata-management protocol, extracted from `@objectstack/objectql` per [ADR-0076](../../docs/adr/0076-objectql-core-tiering.md).
+
+Implements `ObjectStackProtocol`: `sys_metadata` CRUD, draft/publish lifecycle, write locks, package ownership/installation, metadata diagnostics, seed application, and build probes.
+
+It uses a data engine purely as storage + schema registry, injected at runtime via the `MetadataHostEngine` interface — so this package does **not** depend on `@objectstack/objectql`.
diff --git a/packages/metadata-protocol/package.json b/packages/metadata-protocol/package.json
new file mode 100644
index 0000000000..1a57f13afc
--- /dev/null
+++ b/packages/metadata-protocol/package.json
@@ -0,0 +1,61 @@
+{
+  "name": "@objectstack/metadata-protocol",
+  "version": "11.0.0",
+  "license": "Apache-2.0",
+  "description": "ObjectStack metadata management protocol: sys_metadata CRUD, draft/publish, locks, package ownership, diagnostics (ADR-0076).",
+  "type": "module",
+  "main": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "exports": {
+    ".": {
+      "types": "./dist/index.d.ts",
+      "import": "./dist/index.js",
+      "require": "./dist/index.cjs"
+    }
+  },
+  "files": [
+    "dist",
+    "README.md"
+  ],
+  "scripts": {
+    "build": "tsup",
+    "dev": "tsc --watch",
+    "clean": "rm -rf dist",
+    "test": "vitest run",
+    "test:watch": "vitest"
+  },
+  "keywords": [
+    "objectstack",
+    "metadata",
+    "protocol",
+    "sys-metadata"
+  ],
+  "dependencies": {
+    "@objectstack/core": "workspace:*",
+    "@objectstack/formula": "workspace:*",
+    "@objectstack/metadata-core": "workspace:*",
+    "@objectstack/spec": "workspace:*",
+    "@objectstack/types": "workspace:*",
+    "zod": "^4.4.3"
+  },
+  "devDependencies": {
+    "@types/node": "^26.0.0",
+    "tsup": "^8.5.1",
+    "typescript": "^6.0.3",
+    "vitest": "^4.1.9"
+  },
+  "author": "ObjectStack",
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/objectstack-ai/framework.git",
+    "directory": "packages/metadata-protocol"
+  },
+  "homepage": "https://objectstack.ai/docs",
+  "bugs": "https://github.com/objectstack-ai/framework/issues",
+  "publishConfig": {
+    "access": "public"
+  },
+  "engines": {
+    "node": ">=18.0.0"
+  }
+}
diff --git a/packages/objectql/src/build-probes.ts b/packages/metadata-protocol/src/build-probes.ts
similarity index 100%
rename from packages/objectql/src/build-probes.ts
rename to packages/metadata-protocol/src/build-probes.ts
diff --git a/packages/metadata-protocol/src/host-engine.ts b/packages/metadata-protocol/src/host-engine.ts
new file mode 100644
index 0000000000..6c1f4143a4
--- /dev/null
+++ b/packages/metadata-protocol/src/host-engine.ts
@@ -0,0 +1,25 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+import type { IDataEngine } from '@objectstack/core';
+
+/**
+ * The engine surface the metadata protocol needs from its host (ADR-0076).
+ *
+ * The protocol uses the data engine purely as storage + a schema registry; it
+ * is injected a concrete engine at runtime (today `@objectstack/objectql`'s
+ * `ObjectQL`). Typing against this interface — instead of the concrete class —
+ * is what lets `@objectstack/metadata-protocol` avoid a dependency on
+ * `@objectstack/objectql` (which would otherwise form a cycle, since the
+ * ObjectQL plugin constructs the protocol).
+ */
+export interface MetadataHostEngine extends IDataEngine {
+  /** Schema registry (listItems/getItem/registerItem/getObject/registerObject/installPackage/...). */
+  registry: any;
+  /** DDL: create/sync the physical table for an object schema. */
+  syncObjectSchema(...args: any[]): Promise<any>;
+  /** DDL: drop the physical table for an object schema. */
+  dropObjectSchema(...args: any[]): Promise<any>;
+  // Protocol accesses additional engine members structurally; keep it permissive
+  // for this relocation (behavior unchanged — the concrete engine is injected).
+  [key: string]: any;
+}
diff --git a/packages/metadata-protocol/src/index.test.ts b/packages/metadata-protocol/src/index.test.ts
new file mode 100644
index 0000000000..4fabdb5c2f
--- /dev/null
+++ b/packages/metadata-protocol/src/index.test.ts
@@ -0,0 +1,47 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+//
+// Self-contained smoke for @objectstack/metadata-protocol: the package must
+// import cleanly and expose its public surface without needing a data engine.
+// (Protocol behavior is exercised end-to-end by the @objectstack/objectql suite,
+// which injects a real engine.)
+
+import { describe, it, expect } from 'vitest';
+import {
+  ObjectStackProtocolImplementation,
+  ConcurrentUpdateError,
+  normalizeViewMetadata,
+  SysMetadataRepository,
+  resetEnvWritableMetadataTypes,
+  computeMetadataDiagnostics,
+  computeViewReferenceDiagnostics,
+  decorateMetadataItem,
+  SeedLoaderService,
+  runBuildProbes,
+} from './index.js';
+
+describe('@objectstack/metadata-protocol public surface', () => {
+  it('exposes the protocol, repository, seed-loader and probe entry points', () => {
+    expect(typeof ObjectStackProtocolImplementation).toBe('function');
+    expect(typeof SysMetadataRepository).toBe('function');
+    expect(typeof SeedLoaderService).toBe('function');
+    expect(typeof runBuildProbes).toBe('function');
+    expect(ConcurrentUpdateError.prototype).toBeInstanceOf(Error);
+  });
+
+  it('exposes pure metadata helpers', () => {
+    expect(typeof normalizeViewMetadata).toBe('function');
+    expect(typeof computeMetadataDiagnostics).toBe('function');
+    expect(typeof computeViewReferenceDiagnostics).toBe('function');
+    expect(typeof decorateMetadataItem).toBe('function');
+    expect(typeof resetEnvWritableMetadataTypes).toBe('function');
+  });
+
+  it('normalizeViewMetadata passes a non-view item through without throwing', () => {
+    const item = { name: 'acct', label: 'Account' };
+    expect(() => normalizeViewMetadata('object', item, 'acct')).not.toThrow();
+  });
+
+  it('resetEnvWritableMetadataTypes is callable (state reset, no engine needed)', () => {
+    expect(() => resetEnvWritableMetadataTypes()).not.toThrow();
+  });
+});
diff --git a/packages/metadata-protocol/src/index.ts b/packages/metadata-protocol/src/index.ts
new file mode 100644
index 0000000000..718a264f41
--- /dev/null
+++ b/packages/metadata-protocol/src/index.ts
@@ -0,0 +1,31 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+export { ObjectStackProtocolImplementation, ConcurrentUpdateError, normalizeViewMetadata } from './protocol.js';
+
+export { SysMetadataRepository, resetEnvWritableMetadataTypes } from './sys-metadata-repository.js';
+export type {
+  SysMetadataEngine,
+  SysMetadataRepositoryOptions,
+  OverlayState,
+  ExtendedOperation,
+} from './sys-metadata-repository.js';
+
+export {
+  computeMetadataDiagnostics,
+  computeViewReferenceDiagnostics,
+  decorateMetadataItem,
+  decorateMetadataItems,
+} from './metadata-diagnostics.js';
+export type { MetadataDiagnostics } from './metadata-diagnostics.js';
+
+export type { MetadataHostEngine } from './host-engine.js';
+
+export { SeedLoaderService } from './seed-loader.js';
+export { runBuildProbes } from './build-probes.js';
+export type {
+  RuntimeBuildIssue,
+  BuildProbeReport,
+  RunBuildProbesOptions,
+  ProbeEngine,
+  ProbeAnalytics,
+} from './build-probes.js';
diff --git a/packages/objectql/src/metadata-diagnostics.ts b/packages/metadata-protocol/src/metadata-diagnostics.ts
similarity index 100%
rename from packages/objectql/src/metadata-diagnostics.ts
rename to packages/metadata-protocol/src/metadata-diagnostics.ts
diff --git a/packages/objectql/src/protocol.ts b/packages/metadata-protocol/src/protocol.ts
similarity index 99%
rename from packages/objectql/src/protocol.ts
rename to packages/metadata-protocol/src/protocol.ts
index 62125506c4..32105335ca 100644
--- a/packages/objectql/src/protocol.ts
+++ b/packages/metadata-protocol/src/protocol.ts
@@ -3,7 +3,7 @@
 import { ObjectStackProtocol } from '@objectstack/spec/api';
 import { IDataEngine } from '@objectstack/core';
 import { readEnvWithDeprecation } from '@objectstack/types';
-import type { ObjectQL } from './engine.js';
+import type { MetadataHostEngine } from './host-engine.js';
 import { SysMetadataRepository, type SysMetadataEngine } from './sys-metadata-repository.js';
 import { ConflictError } from '@objectstack/metadata-core';
 import type {
@@ -667,7 +667,7 @@ function detectDestructiveObjectChanges(prev: any, next: any): Array<{
 }
 
 export class ObjectStackProtocolImplementation implements ObjectStackProtocol {
-    private engine: ObjectQL;
+    private engine: MetadataHostEngine;
     private getServicesRegistry?: () => Map<string, any>;
     private getFeedService?: () => IFeedService | undefined;
     /**
@@ -694,7 +694,7 @@ export class ObjectStackProtocolImplementation implements ObjectStackProtocol {
         getFeedService?: () => IFeedService | undefined,
         environmentId?: string,
     ) {
-        this.engine = engine as ObjectQL;
+        this.engine = engine as MetadataHostEngine;
         this.getServicesRegistry = getServicesRegistry;
         this.getFeedService = getFeedService;
         this.environmentId = environmentId;
diff --git a/packages/objectql/src/seed-loader.ts b/packages/metadata-protocol/src/seed-loader.ts
similarity index 100%
rename from packages/objectql/src/seed-loader.ts
rename to packages/metadata-protocol/src/seed-loader.ts
diff --git a/packages/objectql/src/sys-metadata-repository.ts b/packages/metadata-protocol/src/sys-metadata-repository.ts
similarity index 100%
rename from packages/objectql/src/sys-metadata-repository.ts
rename to packages/metadata-protocol/src/sys-metadata-repository.ts
diff --git a/packages/metadata-protocol/tsconfig.json b/packages/metadata-protocol/tsconfig.json
new file mode 100644
index 0000000000..20f06375b8
--- /dev/null
+++ b/packages/metadata-protocol/tsconfig.json
@@ -0,0 +1,17 @@
+{
+  "extends": "../../tsconfig.json",
+  "include": [
+    "src/**/*"
+  ],
+  "exclude": [
+    "node_modules",
+    "dist"
+  ],
+  "compilerOptions": {
+    "outDir": "dist",
+    "rootDir": "src",
+    "types": [
+      "node"
+    ]
+  }
+}
diff --git a/packages/metadata-protocol/tsup.config.ts b/packages/metadata-protocol/tsup.config.ts
new file mode 100644
index 0000000000..086365e59b
--- /dev/null
+++ b/packages/metadata-protocol/tsup.config.ts
@@ -0,0 +1,14 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+import { defineConfig } from 'tsup';
+
+export default defineConfig({
+  entry: ['src/index.ts'],
+  splitting: true,
+  sourcemap: true,
+  clean: true,
+  dts: !process.env.OS_SKIP_DTS,
+  format: ['esm', 'cjs'],
+  target: 'es2020',
+  external: ['vitest'],
+});
diff --git a/packages/objectql/package.json b/packages/objectql/package.json
index db0a329654..7b97dade91 100644
--- a/packages/objectql/package.json
+++ b/packages/objectql/package.json
@@ -10,16 +10,22 @@
       "types": "./dist/index.d.ts",
       "import": "./dist/index.mjs",
       "require": "./dist/index.js"
+    },
+    "./core": {
+      "types": "./dist/core.d.ts",
+      "import": "./dist/core.mjs",
+      "require": "./dist/core.js"
     }
   },
   "scripts": {
-    "build": "tsup --config ../../tsup.config.ts",
+    "build": "tsup",
     "test": "vitest run"
   },
   "dependencies": {
     "@objectstack/core": "workspace:*",
     "@objectstack/formula": "workspace:*",
     "@objectstack/metadata-core": "workspace:*",
+    "@objectstack/metadata-protocol": "workspace:*",
     "@objectstack/spec": "workspace:*",
     "@objectstack/types": "workspace:*",
     "ajv": "^8.20.0",
diff --git a/packages/objectql/src/build-probes.test.ts b/packages/objectql/src/build-probes.test.ts
index 57d147a8f1..22190d12c8 100644
--- a/packages/objectql/src/build-probes.test.ts
+++ b/packages/objectql/src/build-probes.test.ts
@@ -1,8 +1,8 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, vi } from 'vitest';
-import { runBuildProbes, type ProbeEngine } from './build-probes.js';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { runBuildProbes, type ProbeEngine } from '@objectstack/metadata-protocol';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 
 /**
  * ADR-0038 L3 — runtime probes. Each probe is one real read; findings are
diff --git a/packages/objectql/src/core-boundary.ratchet.test.ts b/packages/objectql/src/core-boundary.ratchet.test.ts
new file mode 100644
index 0000000000..844fa1686f
--- /dev/null
+++ b/packages/objectql/src/core-boundary.ratchet.test.ts
@@ -0,0 +1,73 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+//
+// ADR-0076 D2 boundary ratchet. The lean engine entry `@objectstack/objectql/core`
+// (src/core.ts) and its entire local import closure must NOT depend on the kernel
+// plugin, the kernel factory, or the metadata-management protocol — so a thin
+// embedder importing `@objectstack/objectql/core` never pulls
+// `@objectstack/metadata-protocol` (or its 268KB) into its graph.
+//
+// If this test fails, you added a forbidden import somewhere reachable from
+// core.ts. Keep metadata/plugin/kernel concerns out of the core closure.
+
+import { describe, it, expect } from 'vitest';
+import { readFileSync } from 'node:fs';
+import { dirname, resolve } from 'node:path';
+import { fileURLToPath } from 'node:url';
+
+const SRC = dirname(fileURLToPath(import.meta.url));
+
+const FORBIDDEN_PACKAGES = ['@objectstack/metadata-protocol'];
+const FORBIDDEN_LOCAL = ['plugin', 'kernel-factory'];
+
+function localImports(source: string): string[] {
+  const out: string[] = [];
+  const re = /(?:from|import)\s*\(?\s*['"](\.\.?\/[^'"]+)['"]/g;
+  let m: RegExpExecArray | null;
+  while ((m = re.exec(source))) out.push(m[1]);
+  return out;
+}
+
+function toTsPath(fromFile: string, spec: string): string {
+  const base = resolve(dirname(fromFile), spec.replace(/\.js$/, ''));
+  return base.endsWith('.ts') ? base : `${base}.ts`;
+}
+
+describe('ADR-0076 D2 — @objectstack/objectql/core boundary', () => {
+  it('core.ts closure pulls neither metadata-protocol nor plugin/kernel-factory', () => {
+    const entry = resolve(SRC, 'core.ts');
+    const visited = new Set<string>();
+    const violations: string[] = [];
+    const stack = [entry];
+
+    while (stack.length) {
+      const file = stack.pop()!;
+      if (visited.has(file)) continue;
+      visited.add(file);
+
+      let src: string;
+      try {
+        src = readFileSync(file, 'utf8');
+      } catch {
+        continue; // generated / non-existent; ignore
+      }
+
+      for (const pkg of FORBIDDEN_PACKAGES) {
+        if (new RegExp(`['"]${pkg.replace('/', '\\/')}['"]`).test(src)) {
+          violations.push(`${file} imports forbidden package ${pkg}`);
+        }
+      }
+
+      for (const spec of localImports(src)) {
+        const base = spec.replace(/\.js$/, '').split('/').pop();
+        if (FORBIDDEN_LOCAL.includes(base ?? '')) {
+          violations.push(`${file} imports forbidden local module ./${base}`);
+        }
+        stack.push(toTsPath(file, spec));
+      }
+    }
+
+    expect(violations, violations.join('\n')).toEqual([]);
+    // sanity: the engine itself IS in the closure
+    expect([...visited].some((f) => f.endsWith('/engine.ts'))).toBe(true);
+  });
+});
diff --git a/packages/objectql/src/core.ts b/packages/objectql/src/core.ts
new file mode 100644
index 0000000000..b01df4d44f
--- /dev/null
+++ b/packages/objectql/src/core.ts
@@ -0,0 +1,78 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+//
+// Lean engine entry (ADR-0076). Exposes the data engine surface — engine,
+// registry, hooks, validation, in-memory aggregation, utilities — WITHOUT the
+// kernel plugin (`ObjectQLPlugin`), the kernel factory, or any metadata
+// management (`@objectstack/metadata-protocol`). Embedders that want only the
+// engine (e.g. a thin gateway) import from `@objectstack/objectql/core` so the
+// 268KB metadata protocol is never pulled into their dependency graph.
+//
+// A boundary ratchet (ADR-0076 D2) keeps this entry free of protocol/plugin
+// imports; do not add `./plugin`, `./kernel-factory`, or `@objectstack/metadata-protocol`
+// re-exports here.
+
+// Registry
+export {
+  SchemaRegistry,
+  applySystemFields,
+  computeFQN,
+  parseFQN,
+  RESERVED_NAMESPACES,
+  DEFAULT_OWNER_PRIORITY,
+  DEFAULT_EXTENDER_PRIORITY,
+} from './registry.js';
+export type { ObjectContributor, SchemaRegistryOptions } from './registry.js';
+
+// Engine
+export { ObjectQL, ObjectRepository, ScopedContext } from './engine.js';
+export type { ObjectQLHostContext, HookHandler, HookEntry, OperationContext, EngineMiddleware } from './engine.js';
+
+// In-memory aggregation fallback
+export { applyInMemoryAggregation, bucketDateValue } from './in-memory-aggregation.js';
+
+// Hook binder & wrappers (declarative-metadata → engine glue)
+export { bindHooksToEngine } from './hook-binder.js';
+export type { BindHooksOptions, BindHooksResult } from './hook-binder.js';
+export { wrapDeclarativeHook } from './hook-wrappers.js';
+export type { WrapDeclarativeOptions } from './hook-wrappers.js';
+
+// Validation
+export { ValidationError, validateRecord } from './validation/record-validator.js';
+export type { FieldValidationError } from './validation/record-validator.js';
+export { evaluateValidationRules, needsPriorRecord, legalNextStates } from './validation/rule-validator.js';
+export type { EvaluateRulesOptions } from './validation/rule-validator.js';
+export {
+  InMemoryHookMetricsRecorder,
+  noopHookMetricsRecorder,
+} from './hook-metrics.js';
+export type {
+  HookMetricsRecorder,
+  HookMetricLabel,
+  HookMetricOutcome,
+  HookSkipReason,
+} from './hook-metrics.js';
+
+// MetadataFacade
+export { MetadataFacade } from './metadata-facade.js';
+
+// Secret-field channel helpers
+export {
+  SECRET_REF_PREFIX,
+  SECRET_MASK,
+  makeSecretRef,
+  isSecretRef,
+  parseSecretRef,
+  collectSecretFields,
+} from './secret-fields.js';
+
+// Utilities
+export {
+  toTitleCase,
+  convertIntrospectedSchemaToObjects,
+} from './util.js';
+export type {
+  IntrospectedColumn,
+  IntrospectedForeignKey,
+  IntrospectedTable,
+  IntrospectedSchema,
+} from './util.js';
diff --git a/packages/objectql/src/index.ts b/packages/objectql/src/index.ts
index 4fc260e68c..23fcfbbb41 100644
--- a/packages/objectql/src/index.ts
+++ b/packages/objectql/src/index.ts
@@ -13,11 +13,11 @@ export {
 export type { ObjectContributor, SchemaRegistryOptions } from './registry.js';
 
 // Export Protocol Implementation
-export { ObjectStackProtocolImplementation } from './protocol.js';
+export { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 
 // ADR-0008 PR-10b: MetadataRepository wrapper over the existing sys_metadata table.
-export { SysMetadataRepository } from './sys-metadata-repository.js';
-export type { SysMetadataEngine, SysMetadataRepositoryOptions } from './sys-metadata-repository.js';
+export { SysMetadataRepository } from '@objectstack/metadata-protocol';
+export type { SysMetadataEngine, SysMetadataRepositoryOptions } from '@objectstack/metadata-protocol';
 
 // Export Engine
 export { ObjectQL, ObjectRepository, ScopedContext } from './engine.js';
@@ -83,9 +83,9 @@ export type {
 
 // Seed loader — materializes `seed` metadata into rows (used by publishMetaItem
 // and the runtime dispatcher/app plugins).
-export { SeedLoaderService } from './seed-loader.js';
+export { SeedLoaderService } from '@objectstack/metadata-protocol';
 
 // ADR-0038 L3 — post-publish runtime probes (one real read per published
 // artifact); findings are BuildIssue-shaped with layer 'runtime'.
-export { runBuildProbes } from './build-probes.js';
-export type { RuntimeBuildIssue, BuildProbeReport, RunBuildProbesOptions } from './build-probes.js';
+export { runBuildProbes } from '@objectstack/metadata-protocol';
+export type { RuntimeBuildIssue, BuildProbeReport, RunBuildProbesOptions } from '@objectstack/metadata-protocol';
diff --git a/packages/objectql/src/layered-overlay-integration.test.ts b/packages/objectql/src/layered-overlay-integration.test.ts
index 8bd87c0d2c..b6669c929c 100644
--- a/packages/objectql/src/layered-overlay-integration.test.ts
+++ b/packages/objectql/src/layered-overlay-integration.test.ts
@@ -18,7 +18,7 @@
 import { describe, it, expect, beforeEach } from 'vitest';
 import { LayeredRepository, InMemoryRepository, hashSpec } from '@objectstack/metadata-core';
 import type { MetaRef } from '@objectstack/metadata-core';
-import { SysMetadataRepository } from './sys-metadata-repository.js';
+import { SysMetadataRepository } from '@objectstack/metadata-protocol';
 
 interface Row {
     id: string;
diff --git a/packages/objectql/src/metadata-diagnostics.test.ts b/packages/objectql/src/metadata-diagnostics.test.ts
index d503cf829a..f31b0fe00b 100644
--- a/packages/objectql/src/metadata-diagnostics.test.ts
+++ b/packages/objectql/src/metadata-diagnostics.test.ts
@@ -10,7 +10,7 @@
  */
 
 import { describe, expect, it } from 'vitest';
-import { computeViewReferenceDiagnostics } from './metadata-diagnostics.js';
+import { computeViewReferenceDiagnostics } from '@objectstack/metadata-protocol';
 
 const objectDef = {
   fields: {
diff --git a/packages/objectql/src/metadata-validation-sweep.test.ts b/packages/objectql/src/metadata-validation-sweep.test.ts
index 59caa80ee4..e3ad7d64e3 100644
--- a/packages/objectql/src/metadata-validation-sweep.test.ts
+++ b/packages/objectql/src/metadata-validation-sweep.test.ts
@@ -21,7 +21,7 @@
  */
 
 import { describe, it, expect, vi } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { SchemaRegistry } from './registry.js';
 import {
     DEFAULT_METADATA_TYPE_REGISTRY,
diff --git a/packages/objectql/src/normalize-view-metadata.test.ts b/packages/objectql/src/normalize-view-metadata.test.ts
index 34f48ebf2e..a3a672c993 100644
--- a/packages/objectql/src/normalize-view-metadata.test.ts
+++ b/packages/objectql/src/normalize-view-metadata.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect } from 'vitest';
-import { normalizeViewMetadata } from './protocol.js';
+import { normalizeViewMetadata } from '@objectstack/metadata-protocol';
 
 /**
  * The `view` write path guarantees a top-level `name` on every view body so
diff --git a/packages/objectql/src/overlay-precedence.test.ts b/packages/objectql/src/overlay-precedence.test.ts
index fc66ec82c7..3a8843da9b 100644
--- a/packages/objectql/src/overlay-precedence.test.ts
+++ b/packages/objectql/src/overlay-precedence.test.ts
@@ -32,7 +32,7 @@
  */
 
 import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { SchemaRegistry } from './registry.js';
 import { canonicalize, hashSpec } from '@objectstack/metadata-core';
 import { DEFAULT_METADATA_TYPE_REGISTRY } from '@objectstack/spec/kernel';
diff --git a/packages/objectql/src/plugin.ts b/packages/objectql/src/plugin.ts
index 6c4c88a91d..d0c1c55a67 100644
--- a/packages/objectql/src/plugin.ts
+++ b/packages/objectql/src/plugin.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { ObjectQL } from './engine.js';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { Plugin, PluginContext } from '@objectstack/core';
 import { StorageNameMapping } from '@objectstack/spec/system';
 import {
diff --git a/packages/objectql/src/protocol-clone-real-engine.test.ts b/packages/objectql/src/protocol-clone-real-engine.test.ts
index ce68e3677b..bdae421c51 100644
--- a/packages/objectql/src/protocol-clone-real-engine.test.ts
+++ b/packages/objectql/src/protocol-clone-real-engine.test.ts
@@ -10,7 +10,7 @@
  */
 
 import { describe, it, expect, beforeEach } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { ObjectQL } from './engine.js';
 
 // A clonable object: business fields + an engine-generated autonumber that
diff --git a/packages/objectql/src/protocol-commit-history.test.ts b/packages/objectql/src/protocol-commit-history.test.ts
index de9003ee4e..5eff21c50c 100644
--- a/packages/objectql/src/protocol-commit-history.test.ts
+++ b/packages/objectql/src/protocol-commit-history.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, vi } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 
 /**
  * ADR-0067 — package-scoped commit history & rollback.
diff --git a/packages/objectql/src/protocol-data.test.ts b/packages/objectql/src/protocol-data.test.ts
index fc460a369d..c25e61e2d5 100644
--- a/packages/objectql/src/protocol-data.test.ts
+++ b/packages/objectql/src/protocol-data.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, vi, beforeEach } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 
 /**
  * Tests for the Protocol Implementation's data methods (findData, getData).
diff --git a/packages/objectql/src/protocol-destructive.test.ts b/packages/objectql/src/protocol-destructive.test.ts
index 3417c4a514..40e8030d13 100644
--- a/packages/objectql/src/protocol-destructive.test.ts
+++ b/packages/objectql/src/protocol-destructive.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, beforeEach, vi } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { SchemaRegistry } from './registry.js';
 
 /**
diff --git a/packages/objectql/src/protocol-discovery.test.ts b/packages/objectql/src/protocol-discovery.test.ts
index 5b4338d9c7..9a3be0e302 100644
--- a/packages/objectql/src/protocol-discovery.test.ts
+++ b/packages/objectql/src/protocol-discovery.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, beforeEach } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { ObjectQL } from './engine.js';
 
 describe('ObjectStackProtocolImplementation - Dynamic Service Discovery', () => {
diff --git a/packages/objectql/src/protocol-feed.test.ts b/packages/objectql/src/protocol-feed.test.ts
index 1d6eaf6d67..e24bd2f27c 100644
--- a/packages/objectql/src/protocol-feed.test.ts
+++ b/packages/objectql/src/protocol-feed.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, beforeEach, vi } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { ObjectQL } from './engine.js';
 import type { IFeedService } from '@objectstack/spec/contracts';
 
diff --git a/packages/objectql/src/protocol-install-package.test.ts b/packages/objectql/src/protocol-install-package.test.ts
index 3e087ab75d..fccf4280f4 100644
--- a/packages/objectql/src/protocol-install-package.test.ts
+++ b/packages/objectql/src/protocol-install-package.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, vi } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 
 /**
  * ADR-0033 package-subsystem consolidation — `protocol.installPackage` is the
diff --git a/packages/objectql/src/protocol-layered-get.test.ts b/packages/objectql/src/protocol-layered-get.test.ts
index 0e74d22cab..b4ad600d7e 100644
--- a/packages/objectql/src/protocol-layered-get.test.ts
+++ b/packages/objectql/src/protocol-layered-get.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, beforeEach, vi } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { SchemaRegistry } from './registry.js';
 
 /**
diff --git a/packages/objectql/src/protocol-lock-enforcement.test.ts b/packages/objectql/src/protocol-lock-enforcement.test.ts
index 00d82b4b26..91405785fb 100644
--- a/packages/objectql/src/protocol-lock-enforcement.test.ts
+++ b/packages/objectql/src/protocol-lock-enforcement.test.ts
@@ -21,7 +21,7 @@
  */
 
 import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { SchemaRegistry } from './registry.js';
 import type { MetadataLock } from '@objectstack/spec/kernel';
 
diff --git a/packages/objectql/src/protocol-meta-types-rich.test.ts b/packages/objectql/src/protocol-meta-types-rich.test.ts
index dd2de01830..33986fee33 100644
--- a/packages/objectql/src/protocol-meta-types-rich.test.ts
+++ b/packages/objectql/src/protocol-meta-types-rich.test.ts
@@ -1,9 +1,9 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, beforeEach, afterEach, vi } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { SchemaRegistry } from './registry.js';
-import { resetEnvWritableMetadataTypes } from './sys-metadata-repository.js';
+import { resetEnvWritableMetadataTypes } from '@objectstack/metadata-protocol';
 
 /**
  * Phase 3a-1 + 3a-env-writable tests.
diff --git a/packages/objectql/src/protocol-meta.test.ts b/packages/objectql/src/protocol-meta.test.ts
index 59379961ab..243d81296d 100644
--- a/packages/objectql/src/protocol-meta.test.ts
+++ b/packages/objectql/src/protocol-meta.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { SchemaRegistry } from './registry.js';
 
 /**
diff --git a/packages/objectql/src/protocol-package-lifecycle.test.ts b/packages/objectql/src/protocol-package-lifecycle.test.ts
index 7695a575fb..20eddfff53 100644
--- a/packages/objectql/src/protocol-package-lifecycle.test.ts
+++ b/packages/objectql/src/protocol-package-lifecycle.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, vi } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 
 /**
  * ADR-0033 — package-level lifecycle beyond publish:
diff --git a/packages/objectql/src/protocol-publish-package-drafts.test.ts b/packages/objectql/src/protocol-publish-package-drafts.test.ts
index 0c109befa9..87314c553c 100644
--- a/packages/objectql/src/protocol-publish-package-drafts.test.ts
+++ b/packages/objectql/src/protocol-publish-package-drafts.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, vi } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 
 /**
  * ADR-0033 — `publishPackageDrafts` promotes every pending draft bound to a
diff --git a/packages/objectql/src/protocol-publish-rollback.test.ts b/packages/objectql/src/protocol-publish-rollback.test.ts
index 29be8765c6..9b2e9b4276 100644
--- a/packages/objectql/src/protocol-publish-rollback.test.ts
+++ b/packages/objectql/src/protocol-publish-rollback.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, expect, it, vi } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 
 /**
  * Protocol-level coverage for the per-item draft / publish / rollback /
diff --git a/packages/objectql/src/protocol-references.test.ts b/packages/objectql/src/protocol-references.test.ts
index f6c80534ac..8335212d63 100644
--- a/packages/objectql/src/protocol-references.test.ts
+++ b/packages/objectql/src/protocol-references.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, beforeEach, vi } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { SchemaRegistry } from './registry.js';
 
 /**
diff --git a/packages/objectql/src/protocol-registry-shadow.test.ts b/packages/objectql/src/protocol-registry-shadow.test.ts
index df55c1ee58..c761a4f584 100644
--- a/packages/objectql/src/protocol-registry-shadow.test.ts
+++ b/packages/objectql/src/protocol-registry-shadow.test.ts
@@ -23,7 +23,7 @@
  */
 
 import { describe, it, expect, beforeEach } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { ObjectQL } from './engine.js';
 import { SchemaRegistry } from './registry.js';
 
diff --git a/packages/objectql/src/protocol-save-meta-repo-path-real-engine.test.ts b/packages/objectql/src/protocol-save-meta-repo-path-real-engine.test.ts
index f6e5d34715..05bf468177 100644
--- a/packages/objectql/src/protocol-save-meta-repo-path-real-engine.test.ts
+++ b/packages/objectql/src/protocol-save-meta-repo-path-real-engine.test.ts
@@ -11,7 +11,7 @@
  */
 
 import { describe, it, expect, beforeEach } from 'vitest';
-import { ObjectStackProtocolImplementation } from './protocol.js';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 import { ObjectQL } from './engine.js';
 
 const sysMetadataObject = {
diff --git a/packages/objectql/src/protocol-save-meta-repo-path.test.ts b/packages/objectql/src/protocol-save-meta-repo-path.test.ts
index 195c426958..381e63e991 100644
--- a/packages/objectql/src/protocol-save-meta-repo-path.test.ts
+++ b/packages/objectql/src/protocol-save-meta-repo-path.test.ts
@@ -2,7 +2,7 @@
 
 import { describe, expect, it } from 'vitest';
 import { hashSpec } from '@objectstack/metadata-core';
-import { ObjectStackProtocolImplementation } from './protocol';
+import { ObjectStackProtocolImplementation } from '@objectstack/metadata-protocol';
 
 /**
  * Repository write-path coverage (post PR-10d.6).
diff --git a/packages/objectql/src/seed-loader-org-fallback.test.ts b/packages/objectql/src/seed-loader-org-fallback.test.ts
index 2c412dc5e7..bebc90d84e 100644
--- a/packages/objectql/src/seed-loader-org-fallback.test.ts
+++ b/packages/objectql/src/seed-loader-org-fallback.test.ts
@@ -8,7 +8,7 @@
 // many orgs → leave rows org-less (genuinely ambiguous → historical behavior).
 
 import { describe, it, expect } from 'vitest';
-import { SeedLoaderService } from './seed-loader';
+import { SeedLoaderService } from '@objectstack/metadata-protocol';
 import { SeedLoaderConfigSchema } from '@objectstack/spec/data';
 
 function harness(orgRows: Array<{ id: string }>) {
diff --git a/packages/objectql/src/sys-metadata-repository-list-drafts.test.ts b/packages/objectql/src/sys-metadata-repository-list-drafts.test.ts
index 1f91327515..b175626a42 100644
--- a/packages/objectql/src/sys-metadata-repository-list-drafts.test.ts
+++ b/packages/objectql/src/sys-metadata-repository-list-drafts.test.ts
@@ -1,7 +1,7 @@
 // Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
 
 import { describe, it, expect, vi } from 'vitest';
-import { SysMetadataRepository } from './sys-metadata-repository.js';
+import { SysMetadataRepository } from '@objectstack/metadata-protocol';
 
 /**
  * ADR-0033 — `listDrafts` surfaces pending DRAFT rows (what an AI authored but
diff --git a/packages/objectql/src/sys-metadata-repository.test.ts b/packages/objectql/src/sys-metadata-repository.test.ts
index f28e0be70e..f918b54d68 100644
--- a/packages/objectql/src/sys-metadata-repository.test.ts
+++ b/packages/objectql/src/sys-metadata-repository.test.ts
@@ -10,7 +10,7 @@
 
 import { describe, it, expect, beforeEach } from 'vitest';
 import { ConflictError, hashSpec } from '@objectstack/metadata-core';
-import { SysMetadataRepository } from './sys-metadata-repository.js';
+import { SysMetadataRepository } from '@objectstack/metadata-protocol';
 
 interface Row {
     id: string;
diff --git a/packages/objectql/tsup.config.ts b/packages/objectql/tsup.config.ts
new file mode 100644
index 0000000000..e664fcc78f
--- /dev/null
+++ b/packages/objectql/tsup.config.ts
@@ -0,0 +1,16 @@
+// Copyright (c) 2025 ObjectStack. Licensed under the Apache-2.0 license.
+
+import { defineConfig } from 'tsup';
+
+export default defineConfig({
+  // `core` is the lean engine entry (ADR-0076) — engine/registry/hooks/validation
+  // only, no kernel plugin or @objectstack/metadata-protocol. `index` is the
+  // batteries-included barrel.
+  entry: ['src/index.ts', 'src/core.ts'],
+  splitting: false,
+  sourcemap: true,
+  clean: true,
+  dts: !process.env.OS_SKIP_DTS,
+  format: ['esm', 'cjs'],
+  target: 'es2020',
+});
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 2b963d4002..14be2822bd 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -917,6 +917,40 @@ importers:
         specifier: ^4.1.9
         version: 4.1.9(@opentelemetry/api@1.9.1)(@types/node@26.0.0)(@vitest/coverage-v8@4.1.9)(happy-dom@20.10.2)(msw@2.14.6(@types/node@26.0.0)(typescript@6.0.3))(vite@8.0.16(@types/node@26.0.0)(esbuild@0.28.1)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0))
 
+  packages/metadata-protocol:
+    dependencies:
+      '@objectstack/core':
+        specifier: workspace:*
+        version: link:../core
+      '@objectstack/formula':
+        specifier: workspace:*
+        version: link:../formula
+      '@objectstack/metadata-core':
+        specifier: workspace:*
+        version: link:../metadata-core
+      '@objectstack/spec':
+        specifier: workspace:*
+        version: link:../spec
+      '@objectstack/types':
+        specifier: workspace:*
+        version: link:../types
+      zod:
+        specifier: ^4.4.3
+        version: 4.4.3
+    devDependencies:
+      '@types/node':
+        specifier: ^26.0.0
+        version: 26.0.0
+      tsup:
+        specifier: ^8.5.1
+        version: 8.5.1(jiti@2.7.0)(postcss@8.5.15)(tsx@4.22.4)(typescript@6.0.3)(yaml@2.9.0)
+      typescript:
+        specifier: ^6.0.3
+        version: 6.0.3
+      vitest:
+        specifier: ^4.1.9
+        version: 4.1.9(@opentelemetry/api@1.9.1)(@types/node@26.0.0)(@vitest/coverage-v8@4.1.9)(happy-dom@20.10.2)(msw@2.14.6(@types/node@26.0.0)(typescript@6.0.3))(vite@8.0.16(@types/node@26.0.0)(esbuild@0.28.1)(jiti@2.7.0)(tsx@4.22.4)(yaml@2.9.0))
+
   packages/objectql:
     dependencies:
       '@objectstack/core':
@@ -928,6 +962,9 @@ importers:
       '@objectstack/metadata-core':
         specifier: workspace:*
         version: link:../metadata-core
+      '@objectstack/metadata-protocol':
+        specifier: workspace:*
+        version: link:../metadata-protocol
       '@objectstack/spec':
         specifier: workspace:*
         version: link:../spec