diff --git a/dataLayer/schema.ts b/dataLayer/schema.ts
index d5debf43e..03fd8f8aa 100644
--- a/dataLayer/schema.ts
+++ b/dataLayer/schema.ts
@@ -23,7 +23,11 @@ const DB_NAME_CONSTRAINTS = Joi.string()
 	.min(1)
 	.max(commonValidators.schema_length.maximum)
 	.pattern(schemaRegex)
-	.messages({ 'string.pattern.base': '{:#label} ' + commonValidators.schema_format.message });
+	.invalid(...hdbTerms.RESERVED_DATABASE_NAMES)
+	.messages({
+		'string.pattern.base': '{:#label} ' + commonValidators.schema_format.message,
+		'any.invalid': "'{#value}' is a reserved name and cannot be used as a database name",
+	});
 
 const TABLE_NAME_CONSTRAINTS = Joi.string()
 	.min(1)
diff --git a/resources/databases.ts b/resources/databases.ts
index 32f141146..94254c3cf 100644
--- a/resources/databases.ts
+++ b/resources/databases.ts
@@ -11,7 +11,12 @@ import {
 } from '../dataLayer/harperBridge/lmdbBridge/lmdbUtility/initializePaths.js';
 import { makeTable } from './Table.ts';
 import OpenEnvironmentObject from '../utility/lmdb/OpenEnvironmentObject.ts';
-import { CONFIG_PARAMS, LEGACY_DATABASES_DIR_NAME, DATABASES_DIR_NAME } from '../utility/hdbTerms.ts';
+import {
+	CONFIG_PARAMS,
+	LEGACY_DATABASES_DIR_NAME,
+	DATABASES_DIR_NAME,
+	RESERVED_DATABASE_NAMES,
+} from '../utility/hdbTerms.ts';
 import { getConfigPath } from '../config/configUtils.ts';
 import { ClientError } from '../utility/errors/hdbError.ts';
 import { _assignPackageExport } from '../globals.js';
@@ -1089,6 +1094,16 @@ export function table<TableResourceType>(tableDefinition: TableDefinition): Tabl
 		cacheControl,
 	} = tableDefinition;
 	if (!databaseName) databaseName = DEFAULT_DATABASE_NAME;
+	// Reject reserved names here too, not only at the operations API: a database
+	// is also created by schema authoring — a `schema.graphql` `@table(database:)`
+	// or a programmatic `table()` call — which bypasses the create_schema
+	// validation. A reserved name collides with a role permission flag (harper#1016).
+	// Deliberately on this authoring path only, NOT in `database()`/`makeTable`: those
+	// are also the load and drop paths, so a reserved-name database created before this
+	// fix still loads (data stays accessible) and can be dropped to remediate.
+	if ((RESERVED_DATABASE_NAMES as readonly string[]).includes(databaseName)) {
+		throw new ClientError(`'${databaseName}' is a reserved name and cannot be used as a database name`);
+	}
 	const rootStore = database({ database: databaseName, table: tableName });
 	const tables = databases[databaseName];
 	logger.trace(`Defining ${tableName} in ${databaseName}`);
diff --git a/resources/roles.ts b/resources/roles.ts
index 117ed0f17..0e150ef14 100644
--- a/resources/roles.ts
+++ b/resources/roles.ts
@@ -2,8 +2,12 @@ import { getDatabases } from './databases.ts';
 import { alterRole, addRole } from '../security/role.ts';
 import { parseDocument } from 'yaml';
 import { isEqual } from 'lodash';
+import { RESERVED_DATABASE_NAMES } from '../utility/hdbTerms.ts';
 
-const USERS_NOT_DBS = ['super_user', 'structure_user'];
+// Named permission flags are keyed alongside per-database permissions in a role's
+// `permission` object; skip them when walking database permissions. This is the
+// same reserved set that database names are rejected from (harper#1016).
+const USERS_NOT_DBS: readonly string[] = RESERVED_DATABASE_NAMES;
 
 /**
  * This is the component for handling role declarations in the Harper system. This will read roles.yaml for role
diff --git a/security/permissionsTranslator.js b/security/permissionsTranslator.js
index d921d4ec7..a80bc4521 100644
--- a/security/permissionsTranslator.js
+++ b/security/permissionsTranslator.js
@@ -132,6 +132,9 @@ function translateRolePermissions(role, schema) {
 	const perms = role.permission;
 	finalPermissions[terms.SYSTEM_SCHEMA_NAME] = perms[terms.SYSTEM_SCHEMA_NAME];
 	finalPermissions.structure_user = perms.structure_user;
+	// Preserve cluster_user like the other named flags so a translated role keeps
+	// what it declared, rather than silently dropping it (harper#1016).
+	finalPermissions.cluster_user = perms.cluster_user;
 	// Preserve operations allowlist and its pre-expanded Set so the gate check in
 	// verifyPerms still has access after role.permission is replaced with fullRolePerms.
 	finalPermissions.operations = perms.operations;
diff --git a/unitTests/commonTestErrors.js b/unitTests/commonTestErrors.js
index 786d6a8f8..debf9ce51 100644
--- a/unitTests/commonTestErrors.js
+++ b/unitTests/commonTestErrors.js
@@ -110,8 +110,6 @@ const TEST_ROLE_PERMS_ERROR = {
 	SU_ROLE_MISSING_ERROR: "Missing 'super_user' key/value in permission set",
 	SU_CU_ROLE_BOOLEAN_ERROR: (role) => `Value for '${role}' permission must be a boolean`,
 	SU_CU_ROLE_NO_PERMS_ALLOWED: (role) => `Roles with '${role}' set to true cannot have other permissions set.`,
-	SU_CU_ROLE_COMBINED_ERROR:
-		"Roles cannot have both 'super_user' and 'cluster_user' values included in their permissions set.",
 	TABLE_PERM_MISSING: (perm) => `Missing table ${perm.toUpperCase()} permission`,
 	TABLE_PERM_NOT_BOOLEAN: (perm) => `Table ${perm.toUpperCase()} permission must be a boolean`,
 	STRUCTURE_USER_ROLE_TYPE_ERROR: (role) => `Value for '${role}' permission must be a boolean or Array`,
diff --git a/unitTests/dataLayer/reservedSchemaNames.test.js b/unitTests/dataLayer/reservedSchemaNames.test.js
new file mode 100644
index 000000000..fda1a7275
--- /dev/null
+++ b/unitTests/dataLayer/reservedSchemaNames.test.js
@@ -0,0 +1,53 @@
+const assert = require('node:assert');
+const schema = require('#src/dataLayer/schema');
+const { table } = require('#src/resources/databases');
+
+// harper#1016: a role's `permission` object keys per-database permissions by
+// database name alongside named flags (super_user / cluster_user /
+// structure_user / operations / _expandedOperations). A database named after one
+// of those flags collides with it, so those names are rejected as database
+// identifiers — at both the operations API (create_schema / create_table) and
+// the schema-authoring path (graphql `@table(database:)` / programmatic table()).
+const RESERVED = ['super_user', 'cluster_user', 'structure_user', 'operations', '_expandedOperations'];
+
+describe('#1016 reserved database names', () => {
+	for (const name of RESERVED) {
+		it(`create_schema rejects reserved name '${name}'`, async () => {
+			await assert.rejects(
+				() => schema.createSchemaStructure({ operation: 'create_schema', schema: name }),
+				/reserved name/,
+				`create_schema accepted reserved name '${name}'`
+			);
+		});
+
+		it(`create_table rejects reserved database '${name}'`, async () => {
+			await assert.rejects(
+				() => schema.createTableStructure({ operation: 'create_table', schema: name, table: 't', primary_key: 'id' }),
+				/reserved name/,
+				`create_table accepted reserved database '${name}'`
+			);
+		});
+
+		it(`schema authoring (table()) rejects reserved database '${name}'`, () => {
+			// graphql `@table(database:)` and programmatic table() funnel through here,
+			// bypassing the operations-API validation. The check throws before any store IO.
+			assert.throws(
+				() => table({ database: name, table: 't', attributes: [{ name: 'id', isPrimaryKey: true }] }),
+				/reserved name/,
+				`table() accepted reserved database '${name}'`
+			);
+		});
+	}
+
+	it('does not reject a non-reserved database name as reserved', async () => {
+		// A normal name must pass the reserved-name check. It may still fail later
+		// (no schema metadata / bridge in this unit context) — just not as reserved.
+		let err;
+		try {
+			await schema.createSchemaStructure({ operation: 'create_schema', schema: 'my_normal_db' });
+		} catch (e) {
+			err = e;
+		}
+		if (err) assert.doesNotMatch(err.message, /reserved name/);
+	});
+});
diff --git a/unitTests/validation/role_validation.test.js b/unitTests/validation/role_validation.test.js
index 5463812c9..d63292a0a 100644
--- a/unitTests/validation/role_validation.test.js
+++ b/unitTests/validation/role_validation.test.js
@@ -249,6 +249,53 @@ describe('Test role_validation module ', () => {
 			expect(test_result).to.equal(null);
 		});
 
+		it('NOMINAL - should return null for valid cluster_user = true ADD_ROLE object', () => {
+			const test_role_json = TEST_ADD_ROLE_OBJECT();
+			test_role_json.permission = { cluster_user: true };
+			const test_result = customValidate_rw(test_role_json, getAddRoleConstraints());
+
+			expect(test_result).to.equal(null);
+		});
+
+		// harper#1016: cluster_user is a boolean role flag, not a database name. A
+		// non-boolean value must report the boolean-type error, not a misleading
+		// "database 'cluster_user' does not exist".
+		it('should return the boolean error (not SCHEMA_NOT_FOUND) for non-boolean cluster_user', () => {
+			const test_role_json = TEST_ADD_ROLE_OBJECT();
+			test_role_json.permission = { cluster_user: 'wut' };
+			const test_result = customValidate_rw(test_role_json, getAddRoleConstraints());
+
+			expect(test_result.statusCode).to.equal(400);
+			expect(test_result.http_resp_msg.main_permissions).to.include(
+				TEST_ROLE_PERMS_ERROR.SU_CU_ROLE_BOOLEAN_ERROR('cluster_user')
+			);
+			expect(test_result.http_resp_msg.main_permissions).to.not.include(
+				TEST_SCHEMA_OP_ERROR.SCHEMA_NOT_FOUND('cluster_user')
+			);
+		});
+
+		// harper#1016 (review): the boolean check must gate on key presence, not truthiness — a falsey
+		// non-boolean (0, '', null) must still be rejected rather than silently skipping both the check
+		// and the database-permission loop. Covers cluster_user and the latent super_user variant.
+		[
+			{ role: 'cluster_user', value: 0 },
+			{ role: 'cluster_user', value: null },
+			{ role: 'cluster_user', value: '' },
+			{ role: 'super_user', value: 0 },
+			{ role: 'super_user', value: null },
+		].forEach(({ role, value }) => {
+			it(`should reject a falsey non-boolean ${role} = ${JSON.stringify(value)} as a boolean error`, () => {
+				const test_role_json = TEST_ADD_ROLE_OBJECT();
+				test_role_json.permission = { [role]: value };
+				const test_result = customValidate_rw(test_role_json, getAddRoleConstraints());
+
+				expect(test_result.statusCode).to.equal(400);
+				expect(test_result.http_resp_msg.main_permissions).to.include(
+					TEST_ROLE_PERMS_ERROR.SU_CU_ROLE_BOOLEAN_ERROR(role)
+				);
+			});
+		});
+
 		it('NOMINAL - should return null for valid ALTER_ROLE object', () => {
 			const test_result = customValidate_rw(TEST_ALTER_ROLE_OBJECT(), getAlterRoleConstraints());
 			expect(test_result).to.equal(null);
diff --git a/utility/hdbTerms.ts b/utility/hdbTerms.ts
index 2c1f04bfe..bba4fa3cb 100644
--- a/utility/hdbTerms.ts
+++ b/utility/hdbTerms.ts
@@ -83,11 +83,36 @@ export const LAUNCH_SERVICE_SCRIPTS = {
 	MAIN: 'dist/bin/harper.js',
 } as const;
 
-/** Specifies user role types */
+/**
+ * Special boolean role flags validated as role types (not database permissions).
+ * `cluster_user` belongs here alongside `super_user`: role validation checks both
+ * are booleans (SU_CU_ROLE_BOOLEAN_ERROR), and without it a non-boolean
+ * `cluster_user` falls through to database validation and reports a misleading
+ * "database 'cluster_user' does not exist" error (harper#1016).
+ */
 export const ROLE_TYPES_ENUM = {
 	SUPER_USER: 'super_user',
+	CLUSTER_USER: 'cluster_user',
 } as const;
 
+/**
+ * Named permission flags that live in a role's `permission` object alongside
+ * per-database permission blocks, which are keyed by database name. A database
+ * named after one of these flags collides with it — the role parser cannot tell
+ * a `super_user` flag from a `super_user` database's permissions — producing
+ * undefined behavior, so these are rejected as database/schema identifiers
+ * (harper#1016). Keep in sync with `UserRoleNamedPermissions` in security/user.ts.
+ * `access` is deliberately NOT here: roles.ts strips it out of `permission`
+ * before persistence (scoped-delegation), so it never collides at runtime.
+ */
+export const RESERVED_DATABASE_NAMES = [
+	'super_user',
+	'cluster_user',
+	'structure_user',
+	'operations',
+	'_expandedOperations',
+] as const;
+
 /** Email address for support requests */
 export const HDB_SUPPORT_ADDRESS = 'support@harperdb.io';
 
diff --git a/validation/role_validation.ts b/validation/role_validation.ts
index d49b862d5..d170db5ef 100644
--- a/validation/role_validation.ts
+++ b/validation/role_validation.ts
@@ -100,7 +100,11 @@ function customValidate(object, constraints) {
 		}
 		//check if cu or su values, if included, are booleans
 		ROLE_TYPES.forEach((role) => {
-			if (object.permission[role as any] && !validate.isBoolean(object.permission[role as any])) {
+			// Gate on key presence, not truthiness: a falsey non-boolean (0, '', null) must still be
+			// rejected as a non-boolean. A truthiness gate would let those skip both this check AND the
+			// database-permission loop below (the key is a role type, so that loop excludes it), so an
+			// add/alter role would silently accept a value that violates the boolean contract.
+			if (role in object.permission && !validate.isBoolean(object.permission[role as any])) {
 				addPermError(HDB_ERROR_MSGS.SU_CU_ROLE_BOOLEAN_ERROR(role as any), validationErrors, undefined, undefined);
 			}
 		});