diff --git a/packages/adk/src/base/registry.ts b/packages/adk/src/base/registry.ts
index a60e4c3c..e27e4c34 100644
--- a/packages/adk/src/base/registry.ts
+++ b/packages/adk/src/base/registry.ts
@@ -88,6 +88,23 @@ const adtToKind = new Map<string, AdkKind>();
 /** ADK kind to ADT main type mapping (reverse) */
 const kindToAdt = new Map<AdkKind, string>();
 
+/**
+ * Test-only: clear all registry state.
+ *
+ * The registry is module-level singleton state populated by side-effectful
+ * `registerObjectType()` calls in `src/objects/repository/**`. Tests that
+ * exercise registration need a clean slate, but production code must never
+ * call this — it would break every ADK object type resolution.
+ *
+ * Name intentionally uses the `__` prefix to signal "not part of the public
+ * API". Do not import this from runtime code.
+ */
+export function __resetRegistryForTests(): void {
+  registry.clear();
+  adtToKind.clear();
+  kindToAdt.clear();
+}
+
 /** Options for registerObjectType */
 export interface RegisterObjectTypeOptions {
   /** ADT REST endpoint path segment (e.g., 'oo/classes', 'ddic/tabletypes') */
diff --git a/packages/adk/tests/fetch-utils.test.ts b/packages/adk/tests/fetch-utils.test.ts
new file mode 100644
index 00000000..eefddfe7
--- /dev/null
+++ b/packages/adk/tests/fetch-utils.test.ts
@@ -0,0 +1,56 @@
+/**
+ * ADK Fetch Utils Unit Tests
+ *
+ * Tests for fetch-utils.ts functions that handle fetch response normalization.
+ */
+
+import { describe, it, expect } from 'vitest';
+import { toText } from '../src/base/fetch-utils';
+
+describe('toText', () => {
+  it('should return string as-is', async () => {
+    const result = await toText('hello world');
+    expect(result).toBe('hello world');
+  });
+
+  it('should handle Response-like object with text method', async () => {
+    const mockResponse = {
+      text: () => Promise.resolve('response text'),
+    };
+    const result = await toText(mockResponse);
+    expect(result).toBe('response text');
+  });
+
+  it('should convert null to empty string', async () => {
+    expect(await toText(null)).toBe('');
+  });
+
+  it('should convert undefined to empty string', async () => {
+    expect(await toText(undefined)).toBe('');
+  });
+
+  it('should convert number to string', async () => {
+    expect(await toText(123)).toBe('123');
+  });
+
+  it('should JSON-stringify plain objects', async () => {
+    const result = await toText({ key: 'value' });
+    expect(result).toBe('{"key":"value"}');
+  });
+
+  it('should JSON-stringify objects with non-function text property', async () => {
+    // `text` is not a function, so the Response-like branch is skipped and
+    // the value falls through to the JSON.stringify path.
+    const result = await toText({ text: 'not a function' });
+    expect(result).toBe('{"text":"not a function"}');
+  });
+
+  it('should fall back to String() when JSON.stringify throws', async () => {
+    // JSON.stringify throws on circular references — the catch branch in
+    // toText() must return the default string coercion instead of propagating.
+    const circular: Record<string, unknown> = {};
+    circular.self = circular;
+    const result = await toText(circular);
+    expect(result).toBe('[object Object]');
+  });
+});
diff --git a/packages/adk/tests/registry.test.ts b/packages/adk/tests/registry.test.ts
new file mode 100644
index 00000000..f357c19b
--- /dev/null
+++ b/packages/adk/tests/registry.test.ts
@@ -0,0 +1,250 @@
+/**
+ * ADK Registry Unit Tests
+ *
+ * Tests for registry.ts functions that handle ADT type to ADK kind mapping
+ * and object type registration/resolution.
+ *
+ * NOTE: The registry is module-level singleton state (`registry`, `adtToKind`,
+ * `kindToAdt` Maps in `src/base/registry.ts`). Each test resets it via
+ * `__resetRegistryForTests()` so ordering and import side effects from other
+ * modules cannot leak in. Do not remove the `beforeEach` call below.
+ */
+
+import { describe, it, expect, beforeEach } from 'vitest';
+import {
+  parseAdtType,
+  getMainType,
+  registerObjectType,
+  resolveType,
+  resolveKind,
+  getKindForType,
+  getTypeForKind,
+  isTypeRegistered,
+  getRegisteredTypes,
+  getRegisteredKinds,
+  getEndpointForType,
+  __resetRegistryForTests,
+  type AdkObjectConstructor,
+} from '../src/base/registry';
+import * as kinds from '../src/base/kinds';
+import type { AdkKind } from '../src/base/kinds';
+
+// Minimal stand-in for an AdkObject constructor; tests only care about
+// identity round-tripping through the registry, not the object shape.
+class MockAdkObject {
+  constructor(
+    public ctx: unknown,
+    public nameOrData: unknown,
+  ) {}
+}
+
+// Single typed cast — the mock intentionally does not implement the full
+// AdkObject contract, so we bridge through `unknown` once here rather than
+// sprinkling `as any` at every call site.
+const mockCtor = MockAdkObject as unknown as AdkObjectConstructor;
+
+beforeEach(() => {
+  __resetRegistryForTests();
+});
+
+describe('parseAdtType', () => {
+  it('should parse full type with sub type', () => {
+    expect(parseAdtType('DEVC/K')).toEqual({
+      full: 'DEVC/K',
+      main: 'DEVC',
+      sub: 'K',
+    });
+  });
+
+  it('should parse main type without sub type', () => {
+    expect(parseAdtType('CLAS')).toEqual({
+      full: 'CLAS',
+      main: 'CLAS',
+      sub: undefined,
+    });
+  });
+
+  it('should handle lowercase input', () => {
+    expect(parseAdtType('tabl/ds')).toEqual({
+      full: 'tabl/ds',
+      main: 'TABL',
+      sub: 'DS',
+    });
+  });
+
+  it('should handle empty sub type', () => {
+    expect(parseAdtType('TABL/')).toEqual({
+      full: 'TABL/',
+      main: 'TABL',
+      sub: '',
+    });
+  });
+});
+
+describe('getMainType', () => {
+  it('should return main type from full type', () => {
+    expect(getMainType('DEVC/K')).toBe('DEVC');
+  });
+
+  it('should return type as-is for main type', () => {
+    expect(getMainType('CLAS')).toBe('CLAS');
+  });
+
+  it('should handle lowercase input', () => {
+    expect(getMainType('prog')).toBe('PROG');
+  });
+});
+
+describe('registerObjectType', () => {
+  it('should register a type with endpoint and nameTransform', () => {
+    registerObjectType('PROG', kinds.Program, mockCtor, {
+      endpoint: 'abap/programs',
+      nameTransform: 'preserve',
+    });
+
+    const entry = resolveType('PROG');
+    expect(entry).toBeDefined();
+    expect(entry?.kind).toBe(kinds.Program);
+    expect(entry?.endpoint).toBe('abap/programs');
+    expect(entry?.nameTransform).toBe('preserve');
+  });
+
+  it('should register without optional parameters', () => {
+    registerObjectType('TEST', 'TestType' as AdkKind, mockCtor);
+
+    const entry = resolveType('TEST');
+    expect(entry).toBeDefined();
+    expect(entry?.kind).toBe('TestType');
+  });
+
+  it('should handle case-insensitive registration', () => {
+    registerObjectType('prog', kinds.Program, mockCtor);
+
+    expect(resolveType('PROG')).toBeDefined();
+    expect(resolveType('prog')).toBeDefined();
+  });
+});
+
+describe('resolveType', () => {
+  it('should resolve exact type match first', () => {
+    registerObjectType('MYTAB', kinds.Table, mockCtor, {
+      endpoint: 'ddic/tables',
+    });
+    registerObjectType('MYTAB/DS', kinds.Structure as AdkKind, mockCtor, {
+      endpoint: 'ddic/structs',
+    });
+
+    expect(resolveType('MYTAB/DS')?.endpoint).toBe('ddic/structs');
+  });
+
+  it('should fall back to main type if full type not found', () => {
+    registerObjectType('ANOTAB', kinds.Table, mockCtor, {
+      endpoint: 'ddic/tables',
+    });
+
+    expect(resolveType('ANOTAB/DS')?.endpoint).toBe('ddic/tables');
+  });
+
+  it('should return undefined for unregistered type', () => {
+    expect(resolveType('UNREGISTERED')).toBeUndefined();
+  });
+});
+
+describe('getKindForType', () => {
+  it('should return kind for registered type', () => {
+    registerObjectType('CLAS', kinds.Class, mockCtor);
+    expect(getKindForType('CLAS')).toBe(kinds.Class);
+  });
+
+  it('should return kind for full type', () => {
+    registerObjectType('TABL', kinds.Table, mockCtor);
+    expect(getKindForType('TABL/DS')).toBe(kinds.Table);
+  });
+
+  it('should return undefined for unregistered type', () => {
+    expect(getKindForType('UNREG')).toBeUndefined();
+  });
+});
+
+describe('getTypeForKind', () => {
+  it('should return ADT type for registered kind', () => {
+    registerObjectType('CLAS', kinds.Class, mockCtor);
+    expect(getTypeForKind(kinds.Class)).toBe('CLAS');
+  });
+
+  it('should return undefined for unregistered kind', () => {
+    expect(getTypeForKind('UnknownKind' as AdkKind)).toBeUndefined();
+  });
+});
+
+describe('isTypeRegistered', () => {
+  it('should return true for registered main type', () => {
+    registerObjectType('CLAS', kinds.Class, mockCtor);
+    expect(isTypeRegistered('CLAS')).toBe(true);
+  });
+
+  it('should return false for unregistered type', () => {
+    expect(isTypeRegistered('UNREG')).toBe(false);
+  });
+
+  it('should treat full types as registered when main type is registered', () => {
+    registerObjectType('TABL', kinds.Table, mockCtor);
+    expect(isTypeRegistered('TABL/DS')).toBe(true);
+  });
+});
+
+describe('getRegisteredTypes', () => {
+  it('should return array of registered types', () => {
+    registerObjectType('TYPE1', 'Type1' as AdkKind, mockCtor);
+    registerObjectType('TYPE2', 'Type2' as AdkKind, mockCtor);
+
+    const types = getRegisteredTypes();
+    expect(types).toContain('TYPE1');
+    expect(types).toContain('TYPE2');
+  });
+
+  it('should return empty array when nothing registered', () => {
+    // Registry was cleared in beforeEach; no registrations have occurred in
+    // this test yet, so the list must be empty (not just array-shaped).
+    expect(getRegisteredTypes()).toEqual([]);
+  });
+});
+
+describe('getRegisteredKinds', () => {
+  it('should return array of registered kinds', () => {
+    registerObjectType('TYPE1', 'Kind1' as AdkKind, mockCtor);
+
+    const kindsList = getRegisteredKinds();
+    expect(kindsList).toContain('Kind1');
+  });
+});
+
+describe('resolveKind', () => {
+  it('should resolve registered kind to entry', () => {
+    registerObjectType('CLAS', kinds.Class, mockCtor, {
+      endpoint: 'oo/classes',
+    });
+
+    const entry = resolveKind(kinds.Class);
+    expect(entry?.kind).toBe(kinds.Class);
+    expect(entry?.endpoint).toBe('oo/classes');
+  });
+
+  it('should return undefined for unregistered kind', () => {
+    expect(resolveKind('UnknownKind' as AdkKind)).toBeUndefined();
+  });
+});
+
+describe('getEndpointForType', () => {
+  it('should return endpoint for registered type', () => {
+    registerObjectType('PROG', kinds.Program, mockCtor, {
+      endpoint: 'abap/programs',
+    });
+
+    expect(getEndpointForType('PROG')).toBe('abap/programs');
+  });
+
+  it('should return undefined for unregistered type', () => {
+    expect(getEndpointForType('UNREG')).toBeUndefined();
+  });
+});