diff --git a/changelog.md b/changelog.md
index 0d75995..259e71a 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,16 @@
 # Changelog
 
+## 2025-11-27 - 2.6.0 - feat(core)
+Add core registry infrastructure: storage, auth, upstream cache, and protocol handlers
+
+- Introduce RegistryStorage: unified storage abstraction with hook support (before/after put/delete/get) and helpers for OCI, NPM, Maven, Cargo, Composer, PyPI, and RubyGems paths and operations
+- Add DefaultAuthProvider and AuthManager: in-memory token store, UUID tokens for package protocols, OCI JWT creation/validation, token lifecycle (create/validate/revoke) and authorization checking
+- Add SmartRegistry orchestrator to initialize and route requests to protocol handlers (OCI, NPM, Maven, Cargo, Composer, PyPI, RubyGems)
+- Implement upstream subsystem: UpstreamCache (in-memory + optional S3 persistence), BaseUpstream with multi-upstream routing, scope rules, retries, TTLs, stale-while-revalidate and negative caching
+- Add circuit breaker implementation for upstream resilience with exponential backoff and per-upstream breakers
+- Add protocol implementations and helpers: NpmRegistry/NpmUpstream (packument/tarball handling and tarball URL rewriting), PypiRegistry (PEP 503/691 support, uploads, metadata), MavenRegistry (artifact/metadata handling and checksum generation), CargoRegistry (sparse index, publish/download/yank)
+- Utility exports and helpers: buffer helpers, plugins aggregator, path helpers, and various protocol-specific helper modules
+
 ## 2025-11-27 - 2.5.0 - feat(pypi,rubygems)
 Add PyPI and RubyGems protocol implementations, upstream caching, and auth/storage improvements
 
diff --git a/test/helpers/registry.ts b/test/helpers/registry.ts
index 1355857..a39b636 100644
--- a/test/helpers/registry.ts
+++ b/test/helpers/registry.ts
@@ -3,7 +3,9 @@ import * as crypto from 'crypto';
 import * as smartarchive from '@push.rocks/smartarchive';
 import * as smartbucket from '@push.rocks/smartbucket';
 import { SmartRegistry } from '../../ts/classes.smartregistry.js';
-import type { IRegistryConfig } from '../../ts/core/interfaces.core.js';
+import type { IRegistryConfig, IAuthToken, TRegistryProtocol } from '../../ts/core/interfaces.core.js';
+import type { IAuthProvider, ITokenOptions } from '../../ts/core/interfaces.auth.js';
+import type { IStorageHooks, IStorageHookContext, IBeforePutResult, IBeforeDeleteResult } from '../../ts/core/interfaces.storage.js';
 
 const testQenv = new qenv.Qenv('./', './.nogit');
 
@@ -608,3 +610,228 @@ export function calculateRubyGemsChecksums(data: Buffer) {
     sha256: crypto.createHash('sha256').update(data).digest('hex'),
   };
 }
+
+// ============================================================================
+// Enterprise Extensibility Test Helpers
+// ============================================================================
+
+/**
+ * Create a mock auth provider for testing pluggable authentication.
+ * Allows customizing behavior for different test scenarios.
+ */
+export function createMockAuthProvider(overrides?: Partial<IAuthProvider>): IAuthProvider {
+  const tokens = new Map<string, IAuthToken>();
+
+  return {
+    init: async () => {},
+    authenticate: async (credentials) => {
+      // Default: always authenticate successfully
+      return credentials.username;
+    },
+    validateToken: async (token, protocol) => {
+      const stored = tokens.get(token);
+      if (stored && (!protocol || stored.type === protocol)) {
+        return stored;
+      }
+      // Mock token for tests
+      if (token === 'valid-mock-token') {
+        return {
+          type: 'npm' as TRegistryProtocol,
+          userId: 'mock-user',
+          scopes: ['npm:*:*:*'],
+        };
+      }
+      return null;
+    },
+    createToken: async (userId, protocol, options) => {
+      const tokenId = `mock-${protocol}-${Date.now()}`;
+      const authToken: IAuthToken = {
+        type: protocol,
+        userId,
+        scopes: options?.scopes || [`${protocol}:*:*:*`],
+        readonly: options?.readonly,
+        expiresAt: options?.expiresIn ? new Date(Date.now() + options.expiresIn * 1000) : undefined,
+      };
+      tokens.set(tokenId, authToken);
+      return tokenId;
+    },
+    revokeToken: async (token) => {
+      tokens.delete(token);
+    },
+    authorize: async (token, resource, action) => {
+      if (!token) return false;
+      if (token.readonly && ['write', 'push', 'delete'].includes(action)) {
+        return false;
+      }
+      return true;
+    },
+    listUserTokens: async (userId) => {
+      const result: Array<{ key: string; readonly: boolean; created: string; protocol?: TRegistryProtocol }> = [];
+      for (const [key, token] of tokens.entries()) {
+        if (token.userId === userId) {
+          result.push({
+            key: `hash-${key.substring(0, 8)}`,
+            readonly: token.readonly || false,
+            created: new Date().toISOString(),
+            protocol: token.type,
+          });
+        }
+      }
+      return result;
+    },
+    ...overrides,
+  };
+}
+
+/**
+ * Create test storage hooks that track all calls.
+ * Useful for verifying hook invocation order and parameters.
+ */
+export function createTrackingHooks(options?: {
+  beforePutAllowed?: boolean;
+  beforeDeleteAllowed?: boolean;
+  throwOnAfterPut?: boolean;
+  throwOnAfterGet?: boolean;
+}): {
+  hooks: IStorageHooks;
+  calls: Array<{ method: string; context: IStorageHookContext; timestamp: number }>;
+} {
+  const calls: Array<{ method: string; context: IStorageHookContext; timestamp: number }> = [];
+
+  return {
+    calls,
+    hooks: {
+      beforePut: async (ctx) => {
+        calls.push({ method: 'beforePut', context: ctx, timestamp: Date.now() });
+        return {
+          allowed: options?.beforePutAllowed !== false,
+          reason: options?.beforePutAllowed === false ? 'Blocked by test' : undefined,
+        };
+      },
+      afterPut: async (ctx) => {
+        calls.push({ method: 'afterPut', context: ctx, timestamp: Date.now() });
+        if (options?.throwOnAfterPut) {
+          throw new Error('Test error in afterPut');
+        }
+      },
+      beforeDelete: async (ctx) => {
+        calls.push({ method: 'beforeDelete', context: ctx, timestamp: Date.now() });
+        return {
+          allowed: options?.beforeDeleteAllowed !== false,
+          reason: options?.beforeDeleteAllowed === false ? 'Blocked by test' : undefined,
+        };
+      },
+      afterDelete: async (ctx) => {
+        calls.push({ method: 'afterDelete', context: ctx, timestamp: Date.now() });
+      },
+      afterGet: async (ctx) => {
+        calls.push({ method: 'afterGet', context: ctx, timestamp: Date.now() });
+        if (options?.throwOnAfterGet) {
+          throw new Error('Test error in afterGet');
+        }
+      },
+    },
+  };
+}
+
+/**
+ * Create a blocking storage hooks implementation for quota testing.
+ */
+export function createQuotaHooks(maxSizeBytes: number): {
+  hooks: IStorageHooks;
+  currentUsage: { bytes: number };
+} {
+  const currentUsage = { bytes: 0 };
+
+  return {
+    currentUsage,
+    hooks: {
+      beforePut: async (ctx) => {
+        const size = ctx.metadata?.size || 0;
+        if (currentUsage.bytes + size > maxSizeBytes) {
+          return { allowed: false, reason: `Quota exceeded: ${currentUsage.bytes + size} > ${maxSizeBytes}` };
+        }
+        return { allowed: true };
+      },
+      afterPut: async (ctx) => {
+        currentUsage.bytes += ctx.metadata?.size || 0;
+      },
+      afterDelete: async (ctx) => {
+        currentUsage.bytes -= ctx.metadata?.size || 0;
+        if (currentUsage.bytes < 0) currentUsage.bytes = 0;
+      },
+    },
+  };
+}
+
+/**
+ * Create a SmartBucket storage backend for upstream cache testing.
+ */
+export async function createTestStorageBackend(): Promise<{
+  storage: {
+    getObject: (key: string) => Promise<Buffer | null>;
+    putObject: (key: string, data: Buffer) => Promise<void>;
+    deleteObject: (key: string) => Promise<void>;
+    listObjects: (prefix: string) => Promise<string[]>;
+  };
+  bucket: smartbucket.Bucket;
+  cleanup: () => Promise<void>;
+}> {
+  const s3AccessKey = await testQenv.getEnvVarOnDemand('S3_ACCESSKEY');
+  const s3SecretKey = await testQenv.getEnvVarOnDemand('S3_SECRETKEY');
+  const s3Endpoint = await testQenv.getEnvVarOnDemand('S3_ENDPOINT');
+  const s3Port = await testQenv.getEnvVarOnDemand('S3_PORT');
+
+  const s3 = new smartbucket.SmartBucket({
+    accessKey: s3AccessKey || 'minioadmin',
+    accessSecret: s3SecretKey || 'minioadmin',
+    endpoint: s3Endpoint || 'localhost',
+    port: parseInt(s3Port || '9000', 10),
+    useSsl: false,
+  });
+
+  const testRunId = generateTestRunId();
+  const bucketName = 'test-cache-' + testRunId.substring(0, 8);
+  const bucket = await s3.createBucket(bucketName);
+
+  const storage = {
+    getObject: async (key: string): Promise<Buffer | null> => {
+      try {
+        const file = await bucket.fastGet({ path: key });
+        if (!file) return null;
+        const stream = await file.createReadStream();
+        const chunks: Buffer[] = [];
+        for await (const chunk of stream) {
+          chunks.push(Buffer.from(chunk));
+        }
+        return Buffer.concat(chunks);
+      } catch {
+        return null;
+      }
+    },
+    putObject: async (key: string, data: Buffer): Promise<void> => {
+      await bucket.fastPut({ path: key, contents: data, overwrite: true });
+    },
+    deleteObject: async (key: string): Promise<void> => {
+      await bucket.fastRemove({ path: key });
+    },
+    listObjects: async (prefix: string): Promise<string[]> => {
+      const files = await bucket.fastList({ prefix });
+      return files.map(f => f.name);
+    },
+  };
+
+  const cleanup = async () => {
+    try {
+      const files = await bucket.fastList({});
+      for (const file of files) {
+        await bucket.fastRemove({ path: file.name });
+      }
+      await s3.removeBucket(bucketName);
+    } catch {
+      // Ignore cleanup errors
+    }
+  };
+
+  return { storage, bucket, cleanup };
+}
diff --git a/test/test.auth.provider.ts b/test/test.auth.provider.ts
new file mode 100644
index 0000000..58a2f78
--- /dev/null
+++ b/test/test.auth.provider.ts
@@ -0,0 +1,412 @@
+import { expect, tap } from '@git.zone/tstest/tapbundle';
+import { DefaultAuthProvider } from '../ts/core/classes.defaultauthprovider.js';
+import { AuthManager } from '../ts/core/classes.authmanager.js';
+import type { IAuthProvider } from '../ts/core/interfaces.auth.js';
+import type { IAuthConfig, IAuthToken } from '../ts/core/interfaces.core.js';
+import { createMockAuthProvider } from './helpers/registry.js';
+
+// ============================================================================
+// Test State
+// ============================================================================
+
+let provider: DefaultAuthProvider;
+let authConfig: IAuthConfig;
+
+// ============================================================================
+// Setup
+// ============================================================================
+
+tap.test('setup: should create DefaultAuthProvider', async () => {
+  authConfig = {
+    jwtSecret: 'test-secret-key-for-jwt-signing',
+    tokenStore: 'memory',
+    npmTokens: { enabled: true },
+    ociTokens: {
+      enabled: true,
+      realm: 'https://auth.example.com/token',
+      service: 'test-registry',
+    },
+    mavenTokens: { enabled: true },
+    cargoTokens: { enabled: true },
+    composerTokens: { enabled: true },
+    pypiTokens: { enabled: true },
+    rubygemsTokens: { enabled: true },
+  };
+
+  provider = new DefaultAuthProvider(authConfig);
+  await provider.init();
+  expect(provider).toBeInstanceOf(DefaultAuthProvider);
+});
+
+// ============================================================================
+// Authentication Tests
+// ============================================================================
+
+tap.test('authenticate: should authenticate new user (auto-registration)', async () => {
+  const userId = await provider.authenticate({
+    username: 'newuser',
+    password: 'newpassword',
+  });
+
+  expect(userId).toEqual('newuser');
+});
+
+tap.test('authenticate: should authenticate existing user with correct password', async () => {
+  // First registration
+  await provider.authenticate({
+    username: 'existinguser',
+    password: 'correctpass',
+  });
+
+  // Second authentication with same credentials
+  const userId = await provider.authenticate({
+    username: 'existinguser',
+    password: 'correctpass',
+  });
+
+  expect(userId).toEqual('existinguser');
+});
+
+tap.test('authenticate: should reject authentication with wrong password', async () => {
+  // First registration
+  await provider.authenticate({
+    username: 'passworduser',
+    password: 'originalpass',
+  });
+
+  // Attempt with wrong password
+  const userId = await provider.authenticate({
+    username: 'passworduser',
+    password: 'wrongpass',
+  });
+
+  expect(userId).toBeNull();
+});
+
+// ============================================================================
+// Token Creation Tests
+// ============================================================================
+
+tap.test('createToken: should create NPM token with correct scopes', async () => {
+  const token = await provider.createToken('testuser', 'npm', {
+    scopes: ['npm:package:*:*'],
+  });
+
+  expect(token).toBeTruthy();
+  expect(typeof token).toEqual('string');
+
+  // Validate the token
+  const validated = await provider.validateToken(token, 'npm');
+  expect(validated).toBeTruthy();
+  expect(validated!.type).toEqual('npm');
+  expect(validated!.userId).toEqual('testuser');
+  expect(validated!.scopes).toContain('npm:package:*:*');
+});
+
+tap.test('createToken: should create Maven token', async () => {
+  const token = await provider.createToken('mavenuser', 'maven', {
+    readonly: true,
+  });
+
+  expect(token).toBeTruthy();
+
+  const validated = await provider.validateToken(token, 'maven');
+  expect(validated).toBeTruthy();
+  expect(validated!.type).toEqual('maven');
+  expect(validated!.readonly).toBeTrue();
+});
+
+tap.test('createToken: should create OCI JWT token with correct claims', async () => {
+  const token = await provider.createToken('ociuser', 'oci', {
+    scopes: ['oci:repository:myrepo:push', 'oci:repository:myrepo:pull'],
+    expiresIn: 3600,
+  });
+
+  expect(token).toBeTruthy();
+  // OCI tokens are JWTs (contain dots)
+  expect(token.split('.').length).toEqual(3);
+
+  const validated = await provider.validateToken(token, 'oci');
+  expect(validated).toBeTruthy();
+  expect(validated!.type).toEqual('oci');
+  expect(validated!.userId).toEqual('ociuser');
+  expect(validated!.scopes.length).toBeGreaterThan(0);
+});
+
+tap.test('createToken: should create token with expiration', async () => {
+  const token = await provider.createToken('expiryuser', 'npm', {
+    expiresIn: 60, // 60 seconds
+  });
+
+  const validated = await provider.validateToken(token, 'npm');
+  expect(validated).toBeTruthy();
+  expect(validated!.expiresAt).toBeTruthy();
+  expect(validated!.expiresAt!.getTime()).toBeGreaterThan(Date.now());
+});
+
+// ============================================================================
+// Token Validation Tests
+// ============================================================================
+
+tap.test('validateToken: should validate UUID token (NPM, Maven, etc.)', async () => {
+  const npmToken = await provider.createToken('validateuser', 'npm');
+  const validated = await provider.validateToken(npmToken);
+
+  expect(validated).toBeTruthy();
+  expect(validated!.type).toEqual('npm');
+  expect(validated!.userId).toEqual('validateuser');
+});
+
+tap.test('validateToken: should validate OCI JWT token', async () => {
+  const ociToken = await provider.createToken('ocivalidate', 'oci', {
+    scopes: ['oci:repository:*:*'],
+  });
+
+  const validated = await provider.validateToken(ociToken, 'oci');
+
+  expect(validated).toBeTruthy();
+  expect(validated!.type).toEqual('oci');
+  expect(validated!.userId).toEqual('ocivalidate');
+});
+
+tap.test('validateToken: should reject expired tokens', async () => {
+  const token = await provider.createToken('expireduser', 'npm', {
+    expiresIn: -1, // Already expired (in the past)
+  });
+
+  // The token should be created but will fail validation due to expiry
+  const validated = await provider.validateToken(token, 'npm');
+
+  // Token should be rejected because it's expired
+  expect(validated).toBeNull();
+});
+
+tap.test('validateToken: should reject invalid token', async () => {
+  const validated = await provider.validateToken('invalid-random-token');
+  expect(validated).toBeNull();
+});
+
+tap.test('validateToken: should reject token with wrong protocol', async () => {
+  const npmToken = await provider.createToken('protocoluser', 'npm');
+
+  // Try to validate as Maven token
+  const validated = await provider.validateToken(npmToken, 'maven');
+  expect(validated).toBeNull();
+});
+
+// ============================================================================
+// Token Revocation Tests
+// ============================================================================
+
+tap.test('revokeToken: should revoke tokens', async () => {
+  const token = await provider.createToken('revokeuser', 'npm');
+
+  // Verify token works before revocation
+  let validated = await provider.validateToken(token);
+  expect(validated).toBeTruthy();
+
+  // Revoke the token
+  await provider.revokeToken(token);
+
+  // Token should no longer be valid
+  validated = await provider.validateToken(token);
+  expect(validated).toBeNull();
+});
+
+// ============================================================================
+// Authorization Tests
+// ============================================================================
+
+tap.test('authorize: should authorize read actions for readonly tokens', async () => {
+  const token = await provider.createToken('readonlyuser', 'npm', {
+    readonly: true,
+    scopes: ['npm:package:*:read'],
+  });
+
+  const validated = await provider.validateToken(token);
+
+  const canRead = await provider.authorize(validated, 'npm:package:lodash', 'read');
+  expect(canRead).toBeTrue();
+
+  const canPull = await provider.authorize(validated, 'npm:package:lodash', 'pull');
+  expect(canPull).toBeTrue();
+});
+
+tap.test('authorize: should deny write actions for readonly tokens', async () => {
+  const token = await provider.createToken('readonlyuser2', 'npm', {
+    readonly: true,
+    scopes: ['npm:package:*:*'],
+  });
+
+  const validated = await provider.validateToken(token);
+
+  const canWrite = await provider.authorize(validated, 'npm:package:lodash', 'write');
+  expect(canWrite).toBeFalse();
+
+  const canPush = await provider.authorize(validated, 'npm:package:lodash', 'push');
+  expect(canPush).toBeFalse();
+
+  const canDelete = await provider.authorize(validated, 'npm:package:lodash', 'delete');
+  expect(canDelete).toBeFalse();
+});
+
+tap.test('authorize: should match scopes with wildcards', async () => {
+  // The scope system uses literal * as wildcard, not glob patterns
+  // npm:*:*:* means "all types, all names, all actions under npm"
+  const token = await provider.createToken('wildcarduser', 'npm', {
+    scopes: ['npm:*:*:*'],
+  });
+
+  const validated = await provider.validateToken(token);
+
+  // Should match any npm resource with full wildcard scope
+  const canAccessAnyPackage = await provider.authorize(validated, 'npm:package:lodash', 'read');
+  expect(canAccessAnyPackage).toBeTrue();
+
+  const canAccessScopedPackage = await provider.authorize(validated, 'npm:package:@myorg/foo', 'write');
+  expect(canAccessScopedPackage).toBeTrue();
+});
+
+tap.test('authorize: should deny access with null token', async () => {
+  const canAccess = await provider.authorize(null, 'npm:package:lodash', 'read');
+  expect(canAccess).toBeFalse();
+});
+
+// ============================================================================
+// List Tokens Tests
+// ============================================================================
+
+tap.test('listUserTokens: should list user tokens', async () => {
+  // Create multiple tokens for the same user
+  const userId = 'listtokenuser';
+  await provider.createToken(userId, 'npm');
+  await provider.createToken(userId, 'maven', { readonly: true });
+  await provider.createToken(userId, 'cargo');
+
+  const tokens = await provider.listUserTokens!(userId);
+
+  expect(tokens.length).toBeGreaterThanOrEqual(3);
+
+  // Check that tokens have expected properties
+  for (const token of tokens) {
+    expect(token.key).toBeTruthy();
+    expect(typeof token.readonly).toEqual('boolean');
+    expect(token.created).toBeTruthy();
+  }
+
+  // Verify we have different protocols
+  const protocols = tokens.map(t => t.protocol);
+  expect(protocols).toContain('npm');
+  expect(protocols).toContain('maven');
+  expect(protocols).toContain('cargo');
+});
+
+// ============================================================================
+// AuthManager Integration Tests
+// ============================================================================
+
+tap.test('AuthManager: should accept custom IAuthProvider', async () => {
+  const mockProvider = createMockAuthProvider({
+    authenticate: async (credentials) => {
+      if (credentials.username === 'custom' && credentials.password === 'pass') {
+        return 'custom-user-id';
+      }
+      return null;
+    },
+  });
+
+  const manager = new AuthManager(authConfig, mockProvider);
+  await manager.init();
+
+  // Use the custom provider
+  const userId = await manager.authenticate({
+    username: 'custom',
+    password: 'pass',
+  });
+
+  expect(userId).toEqual('custom-user-id');
+
+  // Wrong credentials should fail
+  const failed = await manager.authenticate({
+    username: 'custom',
+    password: 'wrong',
+  });
+
+  expect(failed).toBeNull();
+});
+
+tap.test('AuthManager: should use default provider when none specified', async () => {
+  const manager = new AuthManager(authConfig);
+  await manager.init();
+
+  // Should use DefaultAuthProvider internally
+  const userId = await manager.authenticate({
+    username: 'defaultuser',
+    password: 'defaultpass',
+  });
+
+  expect(userId).toEqual('defaultuser');
+});
+
+tap.test('AuthManager: should delegate token creation to provider', async () => {
+  let tokenCreated = false;
+  const mockProvider = createMockAuthProvider({
+    createToken: async (userId, protocol, options) => {
+      tokenCreated = true;
+      return `mock-token-${protocol}-${userId}`;
+    },
+  });
+
+  const manager = new AuthManager(authConfig, mockProvider);
+  await manager.init();
+
+  const token = await manager.createNpmToken('delegateuser', false);
+
+  expect(tokenCreated).toBeTrue();
+  expect(token).toContain('mock-token-npm');
+});
+
+// ============================================================================
+// Edge Cases
+// ============================================================================
+
+tap.test('edge: should handle concurrent token operations', async () => {
+  const promises: Promise<string>[] = [];
+
+  // Create 10 tokens concurrently
+  for (let i = 0; i < 10; i++) {
+    promises.push(provider.createToken(`concurrent-user-${i}`, 'npm'));
+  }
+
+  const tokens = await Promise.all(promises);
+
+  // All tokens should be unique
+  const uniqueTokens = new Set(tokens);
+  expect(uniqueTokens.size).toEqual(10);
+
+  // All tokens should be valid
+  for (const token of tokens) {
+    const validated = await provider.validateToken(token);
+    expect(validated).toBeTruthy();
+  }
+});
+
+tap.test('edge: should handle empty scopes', async () => {
+  const token = await provider.createToken('emptyuser', 'npm', {
+    scopes: [],
+  });
+
+  const validated = await provider.validateToken(token);
+  expect(validated).toBeTruthy();
+  // Even with empty scopes, token should be valid
+});
+
+// ============================================================================
+// Cleanup
+// ============================================================================
+
+tap.test('cleanup', async () => {
+  // No cleanup needed for in-memory provider
+});
+
+export default tap.start();
diff --git a/test/test.storage.hooks.ts b/test/test.storage.hooks.ts
new file mode 100644
index 0000000..da607e0
--- /dev/null
+++ b/test/test.storage.hooks.ts
@@ -0,0 +1,506 @@
+import { expect, tap } from '@git.zone/tstest/tapbundle';
+import * as qenv from '@push.rocks/qenv';
+import { RegistryStorage } from '../ts/core/classes.registrystorage.js';
+import type { IStorageConfig } from '../ts/core/interfaces.core.js';
+import type { IStorageHooks, IStorageHookContext } from '../ts/core/interfaces.storage.js';
+import { createTrackingHooks, createQuotaHooks, generateTestRunId } from './helpers/registry.js';
+
+const testQenv = new qenv.Qenv('./', './.nogit');
+
+// ============================================================================
+// Test State
+// ============================================================================
+
+let storage: RegistryStorage;
+let storageConfig: IStorageConfig;
+let testRunId: string;
+
+// ============================================================================
+// Setup
+// ============================================================================
+
+tap.test('setup: should create storage config', async () => {
+  testRunId = generateTestRunId();
+
+  const s3AccessKey = await testQenv.getEnvVarOnDemand('S3_ACCESSKEY');
+  const s3SecretKey = await testQenv.getEnvVarOnDemand('S3_SECRETKEY');
+  const s3Endpoint = await testQenv.getEnvVarOnDemand('S3_ENDPOINT');
+  const s3Port = await testQenv.getEnvVarOnDemand('S3_PORT');
+
+  storageConfig = {
+    accessKey: s3AccessKey || 'minioadmin',
+    accessSecret: s3SecretKey || 'minioadmin',
+    endpoint: s3Endpoint || 'localhost',
+    port: parseInt(s3Port || '9000', 10),
+    useSsl: false,
+    region: 'us-east-1',
+    bucketName: `test-hooks-${testRunId}`,
+  };
+
+  expect(storageConfig.bucketName).toBeTruthy();
+});
+
+// ============================================================================
+// beforePut Hook Tests
+// ============================================================================
+
+tap.test('beforePut: should be called before storage', async () => {
+  const tracker = createTrackingHooks();
+
+  storage = new RegistryStorage(storageConfig, tracker.hooks);
+  await storage.init();
+
+  // Set context and put object
+  storage.setContext({
+    protocol: 'npm',
+    actor: { userId: 'testuser' },
+    metadata: { packageName: 'test-package' },
+  });
+
+  await storage.putObject('test/beforeput-called.txt', Buffer.from('test data'));
+  storage.clearContext();
+
+  // Verify beforePut was called
+  const beforePutCalls = tracker.calls.filter(c => c.method === 'beforePut');
+  expect(beforePutCalls.length).toEqual(1);
+  expect(beforePutCalls[0].context.operation).toEqual('put');
+  expect(beforePutCalls[0].context.key).toEqual('test/beforeput-called.txt');
+  expect(beforePutCalls[0].context.protocol).toEqual('npm');
+});
+
+tap.test('beforePut: returning {allowed: false} should block storage', async () => {
+  const tracker = createTrackingHooks({ beforePutAllowed: false });
+
+  const blockingStorage = new RegistryStorage(storageConfig, tracker.hooks);
+  await blockingStorage.init();
+
+  blockingStorage.setContext({
+    protocol: 'npm',
+    actor: { userId: 'testuser' },
+  });
+
+  let errorThrown = false;
+  try {
+    await blockingStorage.putObject('test/should-not-exist.txt', Buffer.from('blocked data'));
+  } catch (error) {
+    errorThrown = true;
+    expect((error as Error).message).toContain('Blocked by test');
+  }
+
+  blockingStorage.clearContext();
+
+  expect(errorThrown).toBeTrue();
+
+  // Verify object was NOT stored
+  const result = await blockingStorage.getObject('test/should-not-exist.txt');
+  expect(result).toBeNull();
+});
+
+// ============================================================================
+// afterPut Hook Tests
+// ============================================================================
+
+tap.test('afterPut: should be called after successful storage', async () => {
+  const tracker = createTrackingHooks();
+
+  const trackedStorage = new RegistryStorage(storageConfig, tracker.hooks);
+  await trackedStorage.init();
+
+  trackedStorage.setContext({
+    protocol: 'maven',
+    actor: { userId: 'maven-user' },
+  });
+
+  await trackedStorage.putObject('test/afterput-test.txt', Buffer.from('after put test'));
+  trackedStorage.clearContext();
+
+  // Give async hook time to complete
+  await new Promise(resolve => setTimeout(resolve, 100));
+
+  const afterPutCalls = tracker.calls.filter(c => c.method === 'afterPut');
+  expect(afterPutCalls.length).toEqual(1);
+  expect(afterPutCalls[0].context.operation).toEqual('put');
+});
+
+tap.test('afterPut: should receive correct metadata (size, key, protocol)', async () => {
+  const tracker = createTrackingHooks();
+
+  const metadataStorage = new RegistryStorage(storageConfig, tracker.hooks);
+  await metadataStorage.init();
+
+  const testData = Buffer.from('metadata test data - some content here');
+
+  metadataStorage.setContext({
+    protocol: 'cargo',
+    actor: { userId: 'cargo-user', ip: '192.168.1.100' },
+    metadata: { packageName: 'my-crate', version: '1.0.0' },
+  });
+
+  await metadataStorage.putObject('test/metadata-test.txt', testData);
+  metadataStorage.clearContext();
+
+  await new Promise(resolve => setTimeout(resolve, 100));
+
+  const afterPutCalls = tracker.calls.filter(c => c.method === 'afterPut');
+  expect(afterPutCalls.length).toBeGreaterThanOrEqual(1);
+
+  const call = afterPutCalls[afterPutCalls.length - 1];
+  expect(call.context.metadata?.size).toEqual(testData.length);
+  expect(call.context.key).toEqual('test/metadata-test.txt');
+  expect(call.context.protocol).toEqual('cargo');
+  expect(call.context.actor?.userId).toEqual('cargo-user');
+  expect(call.context.actor?.ip).toEqual('192.168.1.100');
+});
+
+// ============================================================================
+// beforeDelete Hook Tests
+// ============================================================================
+
+tap.test('beforeDelete: should be called before deletion', async () => {
+  const tracker = createTrackingHooks();
+
+  const deleteStorage = new RegistryStorage(storageConfig, tracker.hooks);
+  await deleteStorage.init();
+
+  // First, store an object
+  deleteStorage.setContext({ protocol: 'npm' });
+  await deleteStorage.putObject('test/to-delete.txt', Buffer.from('delete me'));
+
+  // Now delete it
+  await deleteStorage.deleteObject('test/to-delete.txt');
+  deleteStorage.clearContext();
+
+  const beforeDeleteCalls = tracker.calls.filter(c => c.method === 'beforeDelete');
+  expect(beforeDeleteCalls.length).toEqual(1);
+  expect(beforeDeleteCalls[0].context.operation).toEqual('delete');
+  expect(beforeDeleteCalls[0].context.key).toEqual('test/to-delete.txt');
+});
+
+tap.test('beforeDelete: returning {allowed: false} should block deletion', async () => {
+  const tracker = createTrackingHooks({ beforeDeleteAllowed: false });
+
+  const protectedStorage = new RegistryStorage(storageConfig, tracker.hooks);
+  await protectedStorage.init();
+
+  // First store an object
+  protectedStorage.setContext({ protocol: 'npm' });
+  await protectedStorage.putObject('test/protected.txt', Buffer.from('protected data'));
+
+  // Try to delete - should be blocked
+  let errorThrown = false;
+  try {
+    await protectedStorage.deleteObject('test/protected.txt');
+  } catch (error) {
+    errorThrown = true;
+    expect((error as Error).message).toContain('Blocked by test');
+  }
+
+  protectedStorage.clearContext();
+
+  expect(errorThrown).toBeTrue();
+
+  // Verify object still exists
+  const result = await protectedStorage.getObject('test/protected.txt');
+  expect(result).toBeTruthy();
+});
+
+// ============================================================================
+// afterDelete Hook Tests
+// ============================================================================
+
+tap.test('afterDelete: should be called after successful deletion', async () => {
+  const tracker = createTrackingHooks();
+
+  const afterDeleteStorage = new RegistryStorage(storageConfig, tracker.hooks);
+  await afterDeleteStorage.init();
+
+  afterDeleteStorage.setContext({ protocol: 'pypi' });
+  await afterDeleteStorage.putObject('test/delete-tracked.txt', Buffer.from('to be deleted'));
+  await afterDeleteStorage.deleteObject('test/delete-tracked.txt');
+  afterDeleteStorage.clearContext();
+
+  await new Promise(resolve => setTimeout(resolve, 100));
+
+  const afterDeleteCalls = tracker.calls.filter(c => c.method === 'afterDelete');
+  expect(afterDeleteCalls.length).toEqual(1);
+  expect(afterDeleteCalls[0].context.operation).toEqual('delete');
+});
+
+// ============================================================================
+// afterGet Hook Tests
+// ============================================================================
+
+tap.test('afterGet: should be called after reading object', async () => {
+  const tracker = createTrackingHooks();
+
+  const getStorage = new RegistryStorage(storageConfig, tracker.hooks);
+  await getStorage.init();
+
+  // Store an object first
+  getStorage.setContext({ protocol: 'rubygems' });
+  await getStorage.putObject('test/read-test.txt', Buffer.from('read me'));
+
+  // Clear calls to focus on the get
+  tracker.calls.length = 0;
+
+  // Read the object
+  const data = await getStorage.getObject('test/read-test.txt');
+  getStorage.clearContext();
+
+  await new Promise(resolve => setTimeout(resolve, 100));
+
+  expect(data).toBeTruthy();
+  expect(data!.toString()).toEqual('read me');
+
+  const afterGetCalls = tracker.calls.filter(c => c.method === 'afterGet');
+  expect(afterGetCalls.length).toEqual(1);
+  expect(afterGetCalls[0].context.operation).toEqual('get');
+});
+
+// ============================================================================
+// Context Tests
+// ============================================================================
+
+tap.test('context: hooks should receive actor information', async () => {
+  const tracker = createTrackingHooks();
+
+  const actorStorage = new RegistryStorage(storageConfig, tracker.hooks);
+  await actorStorage.init();
+
+  actorStorage.setContext({
+    protocol: 'composer',
+    actor: {
+      userId: 'user-123',
+      tokenId: 'token-abc',
+      ip: '10.0.0.1',
+      userAgent: 'composer/2.0',
+      orgId: 'org-456',
+      sessionId: 'session-xyz',
+    },
+  });
+
+  await actorStorage.putObject('test/actor-test.txt', Buffer.from('actor test'));
+  actorStorage.clearContext();
+
+  const beforePutCall = tracker.calls.find(c => c.method === 'beforePut');
+  expect(beforePutCall).toBeTruthy();
+  expect(beforePutCall!.context.actor?.userId).toEqual('user-123');
+  expect(beforePutCall!.context.actor?.tokenId).toEqual('token-abc');
+  expect(beforePutCall!.context.actor?.ip).toEqual('10.0.0.1');
+  expect(beforePutCall!.context.actor?.userAgent).toEqual('composer/2.0');
+  expect(beforePutCall!.context.actor?.orgId).toEqual('org-456');
+  expect(beforePutCall!.context.actor?.sessionId).toEqual('session-xyz');
+});
+
+tap.test('withContext: should set and clear context correctly', async () => {
+  const tracker = createTrackingHooks();
+
+  const contextStorage = new RegistryStorage(storageConfig, tracker.hooks);
+  await contextStorage.init();
+
+  // Use withContext to ensure automatic cleanup
+  await contextStorage.withContext(
+    {
+      protocol: 'oci',
+      actor: { userId: 'oci-user' },
+    },
+    async () => {
+      await contextStorage.putObject('test/with-context.txt', Buffer.from('context managed'));
+    }
+  );
+
+  const call = tracker.calls.find(c => c.method === 'beforePut');
+  expect(call).toBeTruthy();
+  expect(call!.context.protocol).toEqual('oci');
+  expect(call!.context.actor?.userId).toEqual('oci-user');
+});
+
+tap.test('withContext: should clear context even on error', async () => {
+  const tracker = createTrackingHooks({ beforePutAllowed: false });
+
+  const errorStorage = new RegistryStorage(storageConfig, tracker.hooks);
+  await errorStorage.init();
+
+  let errorThrown = false;
+  try {
+    await errorStorage.withContext(
+      {
+        protocol: 'npm',
+        actor: { userId: 'error-user' },
+      },
+      async () => {
+        await errorStorage.putObject('test/error-context.txt', Buffer.from('will fail'));
+      }
+    );
+  } catch {
+    errorThrown = true;
+  }
+
+  expect(errorThrown).toBeTrue();
+
+  // Verify context was cleared - next operation without context should work
+  // (hooks won't be called without context)
+  tracker.hooks.beforePut = async () => ({ allowed: true });
+  await errorStorage.putObject('test/after-error.txt', Buffer.from('ok'));
+});
+
+// ============================================================================
+// Graceful Degradation Tests
+// ============================================================================
+
+tap.test('graceful: hooks should not fail the operation if afterPut throws', async () => {
+  const tracker = createTrackingHooks({ throwOnAfterPut: true });
+
+  const gracefulStorage = new RegistryStorage(storageConfig, tracker.hooks);
+  await gracefulStorage.init();
+
+  gracefulStorage.setContext({ protocol: 'npm' });
+
+  // This should NOT throw even though afterPut throws
+  let errorThrown = false;
+  try {
+    await gracefulStorage.putObject('test/graceful-afterput.txt', Buffer.from('should succeed'));
+  } catch {
+    errorThrown = true;
+  }
+
+  gracefulStorage.clearContext();
+
+  expect(errorThrown).toBeFalse();
+
+  // Verify object was stored
+  const data = await gracefulStorage.getObject('test/graceful-afterput.txt');
+  expect(data).toBeTruthy();
+});
+
+tap.test('graceful: hooks should not fail the operation if afterGet throws', async () => {
+  const tracker = createTrackingHooks({ throwOnAfterGet: true });
+
+  const gracefulGetStorage = new RegistryStorage(storageConfig, tracker.hooks);
+  await gracefulGetStorage.init();
+
+  // Store first
+  gracefulGetStorage.setContext({ protocol: 'maven' });
+  await gracefulGetStorage.putObject('test/graceful-afterget.txt', Buffer.from('read me gracefully'));
+
+  // Read should succeed even though afterGet throws
+  let errorThrown = false;
+  try {
+    const data = await gracefulGetStorage.getObject('test/graceful-afterget.txt');
+    expect(data).toBeTruthy();
+  } catch {
+    errorThrown = true;
+  }
+
+  gracefulGetStorage.clearContext();
+
+  expect(errorThrown).toBeFalse();
+});
+
+// ============================================================================
+// Quota Hooks Tests
+// ============================================================================
+
+tap.test('quota: should block storage when quota exceeded', async () => {
+  const maxSize = 100; // 100 bytes max
+  const quotaTracker = createQuotaHooks(maxSize);
+
+  const quotaStorage = new RegistryStorage(storageConfig, quotaTracker.hooks);
+  await quotaStorage.init();
+
+  quotaStorage.setContext({
+    protocol: 'npm',
+    actor: { userId: 'quota-user' },
+  });
+
+  // Store 50 bytes - should succeed
+  await quotaStorage.putObject('test/quota-1.txt', Buffer.from('x'.repeat(50)));
+  expect(quotaTracker.currentUsage.bytes).toEqual(50);
+
+  // Try to store 60 more bytes - should fail (total would be 110)
+  let errorThrown = false;
+  try {
+    await quotaStorage.putObject('test/quota-2.txt', Buffer.from('x'.repeat(60)));
+  } catch (error) {
+    errorThrown = true;
+    expect((error as Error).message).toContain('Quota exceeded');
+  }
+
+  quotaStorage.clearContext();
+
+  expect(errorThrown).toBeTrue();
+  expect(quotaTracker.currentUsage.bytes).toEqual(50); // Still 50, not 110
+});
+
+tap.test('quota: should update usage after delete', async () => {
+  const maxSize = 200;
+  const quotaTracker = createQuotaHooks(maxSize);
+
+  const quotaDelStorage = new RegistryStorage(storageConfig, quotaTracker.hooks);
+  await quotaDelStorage.init();
+
+  quotaDelStorage.setContext({
+    protocol: 'npm',
+    metadata: { size: 75 },
+  });
+
+  // Store and track
+  await quotaDelStorage.putObject('test/quota-del.txt', Buffer.from('x'.repeat(75)));
+  expect(quotaTracker.currentUsage.bytes).toEqual(75);
+
+  // Delete and verify usage decreases
+  await quotaDelStorage.deleteObject('test/quota-del.txt');
+
+  await new Promise(resolve => setTimeout(resolve, 100));
+
+  quotaDelStorage.clearContext();
+
+  // Usage should be reduced (though exact value depends on metadata)
+  expect(quotaTracker.currentUsage.bytes).toBeLessThanOrEqual(75);
+});
+
+// ============================================================================
+// setHooks Tests
+// ============================================================================
+
+tap.test('setHooks: should allow setting hooks after construction', async () => {
+  const lateStorage = new RegistryStorage(storageConfig);
+  await lateStorage.init();
+
+  // Initially no hooks
+  await lateStorage.putObject('test/no-hooks.txt', Buffer.from('no hooks yet'));
+
+  // Add hooks later
+  const tracker = createTrackingHooks();
+  lateStorage.setHooks(tracker.hooks);
+
+  lateStorage.setContext({ protocol: 'npm' });
+  await lateStorage.putObject('test/with-late-hooks.txt', Buffer.from('now with hooks'));
+  lateStorage.clearContext();
+
+  const beforePutCalls = tracker.calls.filter(c => c.method === 'beforePut');
+  expect(beforePutCalls.length).toEqual(1);
+});
+
+// ============================================================================
+// Cleanup
+// ============================================================================
+
+tap.test('cleanup: should clean up test bucket', async () => {
+  if (storage) {
+    // Clean up test objects
+    const prefixes = ['test/'];
+    for (const prefix of prefixes) {
+      try {
+        const objects = await storage.listObjects(prefix);
+        for (const obj of objects) {
+          await storage.deleteObject(obj);
+        }
+      } catch {
+        // Ignore cleanup errors
+      }
+    }
+  }
+});
+
+export default tap.start();
diff --git a/test/test.upstream.cache.s3.ts b/test/test.upstream.cache.s3.ts
new file mode 100644
index 0000000..29d19a1
--- /dev/null
+++ b/test/test.upstream.cache.s3.ts
@@ -0,0 +1,598 @@
+import { expect, tap } from '@git.zone/tstest/tapbundle';
+import * as qenv from '@push.rocks/qenv';
+import * as smartbucket from '@push.rocks/smartbucket';
+import { UpstreamCache } from '../ts/upstream/classes.upstreamcache.js';
+import type { IUpstreamFetchContext, IUpstreamCacheConfig } from '../ts/upstream/interfaces.upstream.js';
+import type { IStorageBackend } from '../ts/core/interfaces.core.js';
+import { generateTestRunId } from './helpers/registry.js';
+
+const testQenv = new qenv.Qenv('./', './.nogit');
+
+// ============================================================================
+// Test State
+// ============================================================================
+
+let cache: UpstreamCache;
+let storageBackend: IStorageBackend;
+let s3Bucket: smartbucket.Bucket;
+let smartBucket: smartbucket.SmartBucket;
+let testRunId: string;
+let bucketName: string;
+
+// ============================================================================
+// Helper Functions
+// ============================================================================
+
+function createFetchContext(overrides?: Partial<IUpstreamFetchContext>): IUpstreamFetchContext {
+  // Use resource name as path to ensure unique cache keys
+  const resource = overrides?.resource || 'lodash';
+  return {
+    protocol: 'npm',
+    resource,
+    resourceType: 'packument',
+    path: `/${resource}`,
+    method: 'GET',
+    headers: {},
+    query: {},
+    ...overrides,
+  };
+}
+
+// ============================================================================
+// Setup
+// ============================================================================
+
+tap.test('setup: should create S3 storage backend', async () => {
+  testRunId = generateTestRunId();
+  bucketName = `test-ucache-${testRunId.substring(0, 8)}`;
+
+  const s3AccessKey = await testQenv.getEnvVarOnDemand('S3_ACCESSKEY');
+  const s3SecretKey = await testQenv.getEnvVarOnDemand('S3_SECRETKEY');
+  const s3Endpoint = await testQenv.getEnvVarOnDemand('S3_ENDPOINT');
+  const s3Port = await testQenv.getEnvVarOnDemand('S3_PORT');
+
+  smartBucket = new smartbucket.SmartBucket({
+    accessKey: s3AccessKey || 'minioadmin',
+    accessSecret: s3SecretKey || 'minioadmin',
+    endpoint: s3Endpoint || 'localhost',
+    port: parseInt(s3Port || '9000', 10),
+    useSsl: false,
+  });
+
+  s3Bucket = await smartBucket.createBucket(bucketName);
+
+  // Create storage backend adapter
+  storageBackend = {
+    getObject: async (key: string): Promise<Buffer | null> => {
+      try {
+        // fastGet returns Buffer directly (or undefined if not found)
+        const data = await s3Bucket.fastGet({ path: key });
+        if (!data) {
+          return null;
+        }
+        return data;
+      } catch (error) {
+        // fastGet throws if object doesn't exist
+        return null;
+      }
+    },
+    putObject: async (key: string, data: Buffer): Promise<void> => {
+      await s3Bucket.fastPut({ path: key, contents: data, overwrite: true });
+    },
+    deleteObject: async (key: string): Promise<void> => {
+      await s3Bucket.fastRemove({ path: key });
+    },
+    listObjects: async (prefix: string): Promise<string[]> => {
+      const paths: string[] = [];
+      for await (const path of s3Bucket.listAllObjects(prefix)) {
+        paths.push(path);
+      }
+      return paths;
+    },
+  };
+
+  expect(storageBackend).toBeTruthy();
+});
+
+tap.test('setup: should create UpstreamCache with S3 storage', async () => {
+  cache = new UpstreamCache(
+    { enabled: true, defaultTtlSeconds: 300 },
+    10000,
+    storageBackend
+  );
+
+  expect(cache.isEnabled()).toBeTrue();
+  expect(cache.hasStorage()).toBeTrue();
+});
+
+// ============================================================================
+// Basic Cache Operations
+// ============================================================================
+
+tap.test('cache: should store cache entry in S3', async () => {
+  const context = createFetchContext({ resource: 'store-test' });
+  const testData = Buffer.from(JSON.stringify({ name: 'store-test', version: '1.0.0' }));
+  const upstreamUrl = 'https://registry.npmjs.org';
+
+  await cache.set(
+    context,
+    testData,
+    'application/json',
+    { 'etag': '"abc123"' },
+    'npmjs',
+    upstreamUrl
+  );
+
+  // Verify in S3
+  const stats = cache.getStats();
+  expect(stats.totalEntries).toBeGreaterThanOrEqual(1);
+});
+
+tap.test('cache: should retrieve cache entry from S3', async () => {
+  const context = createFetchContext({ resource: 'retrieve-test' });
+  const testData = Buffer.from('retrieve test data');
+  const upstreamUrl = 'https://registry.npmjs.org';
+
+  await cache.set(
+    context,
+    testData,
+    'application/octet-stream',
+    {},
+    'npmjs',
+    upstreamUrl
+  );
+
+  const entry = await cache.get(context, upstreamUrl);
+
+  expect(entry).toBeTruthy();
+  expect(entry!.data.toString()).toEqual('retrieve test data');
+  expect(entry!.contentType).toEqual('application/octet-stream');
+  expect(entry!.upstreamId).toEqual('npmjs');
+});
+
+// ============================================================================
+// Multi-Upstream URL Tests
+// ============================================================================
+
+tap.test('cache: should include upstream URL in cache path', async () => {
+  const context = createFetchContext({ resource: 'url-path-test' });
+  const testData = Buffer.from('url path test');
+
+  await cache.set(
+    context,
+    testData,
+    'text/plain',
+    {},
+    'npmjs',
+    'https://registry.npmjs.org'
+  );
+
+  // The cache key should include the escaped URL
+  const entry = await cache.get(context, 'https://registry.npmjs.org');
+  expect(entry).toBeTruthy();
+  expect(entry!.data.toString()).toEqual('url path test');
+});
+
+tap.test('cache: should handle multiple upstreams with different URLs', async () => {
+  const context = createFetchContext({ resource: '@company/private-pkg' });
+
+  // Store from private upstream
+  const privateData = Buffer.from('private package data');
+  await cache.set(
+    context,
+    privateData,
+    'application/json',
+    {},
+    'private-npm',
+    'https://npm.company.com'
+  );
+
+  // Store from public upstream (same resource name, different upstream)
+  const publicData = Buffer.from('public package data');
+  await cache.set(
+    context,
+    publicData,
+    'application/json',
+    {},
+    'public-npm',
+    'https://registry.npmjs.org'
+  );
+
+  // Retrieve from private - should get private data
+  const privateEntry = await cache.get(context, 'https://npm.company.com');
+  expect(privateEntry).toBeTruthy();
+  expect(privateEntry!.data.toString()).toEqual('private package data');
+  expect(privateEntry!.upstreamId).toEqual('private-npm');
+
+  // Retrieve from public - should get public data
+  const publicEntry = await cache.get(context, 'https://registry.npmjs.org');
+  expect(publicEntry).toBeTruthy();
+  expect(publicEntry!.data.toString()).toEqual('public package data');
+  expect(publicEntry!.upstreamId).toEqual('public-npm');
+});
+
+// ============================================================================
+// TTL and Expiration Tests
+// ============================================================================
+
+tap.test('cache: should respect TTL expiration', async () => {
+  // Create cache with very short TTL
+  const shortTtlCache = new UpstreamCache(
+    {
+      enabled: true,
+      defaultTtlSeconds: 1, // 1 second TTL
+      staleWhileRevalidate: false,
+      staleMaxAgeSeconds: 0,
+      immutableTtlSeconds: 1,
+      negativeCacheTtlSeconds: 1,
+    },
+    1000,
+    storageBackend
+  );
+
+  const context = createFetchContext({ resource: 'ttl-test' });
+  const testData = Buffer.from('expires soon');
+
+  await shortTtlCache.set(
+    context,
+    testData,
+    'text/plain',
+    {},
+    'test-upstream',
+    'https://test.example.com'
+  );
+
+  // Should exist immediately
+  let entry = await shortTtlCache.get(context, 'https://test.example.com');
+  expect(entry).toBeTruthy();
+
+  // Wait for expiration
+  await new Promise(resolve => setTimeout(resolve, 1500));
+
+  // Should be expired now
+  entry = await shortTtlCache.get(context, 'https://test.example.com');
+  expect(entry).toBeNull();
+
+  shortTtlCache.stop();
+});
+
+tap.test('cache: should serve stale content during stale-while-revalidate window', async () => {
+  const staleCache = new UpstreamCache(
+    {
+      enabled: true,
+      defaultTtlSeconds: 1, // 1 second fresh
+      staleWhileRevalidate: true,
+      staleMaxAgeSeconds: 60, // 60 seconds stale window
+      immutableTtlSeconds: 1,
+      negativeCacheTtlSeconds: 1,
+    },
+    1000,
+    storageBackend
+  );
+
+  const context = createFetchContext({ resource: 'stale-test' });
+  const testData = Buffer.from('stale but usable');
+
+  await staleCache.set(
+    context,
+    testData,
+    'text/plain',
+    {},
+    'stale-upstream',
+    'https://stale.example.com'
+  );
+
+  // Wait for fresh period to expire
+  await new Promise(resolve => setTimeout(resolve, 1500));
+
+  // Should still be available but marked as stale
+  const entry = await staleCache.get(context, 'https://stale.example.com');
+  expect(entry).toBeTruthy();
+  expect(entry!.stale).toBeTrue();
+  expect(entry!.data.toString()).toEqual('stale but usable');
+
+  staleCache.stop();
+});
+
+tap.test('cache: should reject content past stale deadline', async () => {
+  const veryShortCache = new UpstreamCache(
+    {
+      enabled: true,
+      defaultTtlSeconds: 1,
+      staleWhileRevalidate: true,
+      staleMaxAgeSeconds: 1, // Only 1 second stale window
+      immutableTtlSeconds: 1,
+      negativeCacheTtlSeconds: 1,
+    },
+    1000,
+    storageBackend
+  );
+
+  const context = createFetchContext({ resource: 'very-stale-test' });
+  await veryShortCache.set(
+    context,
+    Buffer.from('will expire completely'),
+    'text/plain',
+    {},
+    'short-upstream',
+    'https://short.example.com'
+  );
+
+  // Wait for both fresh AND stale periods to expire
+  await new Promise(resolve => setTimeout(resolve, 2500));
+
+  const entry = await veryShortCache.get(context, 'https://short.example.com');
+  expect(entry).toBeNull();
+
+  veryShortCache.stop();
+});
+
+// ============================================================================
+// Negative Cache Tests
+// ============================================================================
+
+tap.test('cache: should store negative cache entries (404)', async () => {
+  const context = createFetchContext({ resource: 'not-found-pkg' });
+  const upstreamUrl = 'https://registry.npmjs.org';
+
+  await cache.setNegative(context, 'npmjs', upstreamUrl);
+
+  const hasNegative = await cache.hasNegative(context, upstreamUrl);
+  expect(hasNegative).toBeTrue();
+});
+
+tap.test('cache: should retrieve negative cache entries', async () => {
+  const context = createFetchContext({ resource: 'negative-retrieve-test' });
+  const upstreamUrl = 'https://registry.npmjs.org';
+
+  await cache.setNegative(context, 'npmjs', upstreamUrl);
+
+  const entry = await cache.get(context, upstreamUrl);
+  expect(entry).toBeTruthy();
+  expect(entry!.data.length).toEqual(0); // Empty buffer indicates 404
+});
+
+// ============================================================================
+// Eviction Tests
+// ============================================================================
+
+tap.test('cache: should evict oldest entries when memory limit reached', async () => {
+  // Create cache with very small limit
+  const smallCache = new UpstreamCache(
+    { enabled: true, defaultTtlSeconds: 300 },
+    5, // Only 5 entries
+    storageBackend
+  );
+
+  // Add 10 entries
+  for (let i = 0; i < 10; i++) {
+    const context = createFetchContext({ resource: `evict-test-${i}` });
+    await smallCache.set(
+      context,
+      Buffer.from(`data ${i}`),
+      'text/plain',
+      {},
+      'evict-upstream',
+      'https://evict.example.com'
+    );
+  }
+
+  const stats = smallCache.getStats();
+  // Should have evicted some entries
+  expect(stats.totalEntries).toBeLessThanOrEqual(5);
+
+  smallCache.stop();
+});
+
+// ============================================================================
+// Query Parameter Tests
+// ============================================================================
+
+tap.test('cache: cache key should include query parameters', async () => {
+  const context1 = createFetchContext({
+    resource: 'query-test',
+    query: { version: '1.0.0' },
+  });
+
+  const context2 = createFetchContext({
+    resource: 'query-test',
+    query: { version: '2.0.0' },
+  });
+
+  const upstreamUrl = 'https://registry.npmjs.org';
+
+  // Store with v1 query
+  await cache.set(
+    context1,
+    Buffer.from('version 1 data'),
+    'text/plain',
+    {},
+    'query-upstream',
+    upstreamUrl
+  );
+
+  // Store with v2 query
+  await cache.set(
+    context2,
+    Buffer.from('version 2 data'),
+    'text/plain',
+    {},
+    'query-upstream',
+    upstreamUrl
+  );
+
+  // Retrieve v1 - should get v1 data
+  const entry1 = await cache.get(context1, upstreamUrl);
+  expect(entry1).toBeTruthy();
+  expect(entry1!.data.toString()).toEqual('version 1 data');
+
+  // Retrieve v2 - should get v2 data
+  const entry2 = await cache.get(context2, upstreamUrl);
+  expect(entry2).toBeTruthy();
+  expect(entry2!.data.toString()).toEqual('version 2 data');
+});
+
+// ============================================================================
+// S3 Persistence Tests
+// ============================================================================
+
+tap.test('cache: should load from S3 on memory cache miss', async () => {
+  // Use a unique resource name for this test
+  const uniqueResource = `persist-test-${Date.now()}`;
+  const persistContext = createFetchContext({ resource: uniqueResource });
+  const upstreamUrl = 'https://persist.example.com';
+
+  // Store in first cache instance
+  await cache.set(
+    persistContext,
+    Buffer.from('persisted data'),
+    'text/plain',
+    {},
+    'persist-upstream',
+    upstreamUrl
+  );
+
+  // Wait for S3 write to complete
+  await new Promise(resolve => setTimeout(resolve, 200));
+
+  // Verify the entry is in the original cache's memory
+  const originalEntry = await cache.get(persistContext, upstreamUrl);
+  expect(originalEntry).toBeTruthy();
+
+  // Create a new cache instance (simulates restart) with SAME storage backend
+  const freshCache = new UpstreamCache(
+    { enabled: true, defaultTtlSeconds: 300 },
+    10000,
+    storageBackend
+  );
+
+  // Fresh cache has empty memory, should load from S3
+  const entry = await freshCache.get(persistContext, upstreamUrl);
+
+  expect(entry).toBeTruthy();
+  expect(entry!.data.toString()).toEqual('persisted data');
+
+  freshCache.stop();
+});
+
+// ============================================================================
+// Cache Stats Tests
+// ============================================================================
+
+tap.test('cache: should return accurate stats', async () => {
+  const statsCache = new UpstreamCache(
+    { enabled: true, defaultTtlSeconds: 300 },
+    1000,
+    storageBackend
+  );
+
+  // Add some entries
+  for (let i = 0; i < 3; i++) {
+    const context = createFetchContext({ resource: `stats-test-${i}` });
+    await statsCache.set(
+      context,
+      Buffer.from(`stats data ${i}`),
+      'text/plain',
+      {},
+      'stats-upstream',
+      'https://stats.example.com'
+    );
+  }
+
+  // Add a negative entry
+  const negContext = createFetchContext({ resource: 'stats-negative' });
+  await statsCache.setNegative(negContext, 'stats-upstream', 'https://stats.example.com');
+
+  const stats = statsCache.getStats();
+
+  expect(stats.totalEntries).toBeGreaterThanOrEqual(4);
+  expect(stats.enabled).toBeTrue();
+  expect(stats.hasStorage).toBeTrue();
+  expect(stats.maxEntries).toEqual(1000);
+
+  statsCache.stop();
+});
+
+// ============================================================================
+// Invalidation Tests
+// ============================================================================
+
+tap.test('cache: should invalidate specific cache entry', async () => {
+  const invalidateContext = createFetchContext({ resource: 'invalidate-test' });
+  const upstreamUrl = 'https://invalidate.example.com';
+
+  await cache.set(
+    invalidateContext,
+    Buffer.from('to be invalidated'),
+    'text/plain',
+    {},
+    'inv-upstream',
+    upstreamUrl
+  );
+
+  // Verify it exists
+  let entry = await cache.get(invalidateContext, upstreamUrl);
+  expect(entry).toBeTruthy();
+
+  // Invalidate
+  const deleted = await cache.invalidate(invalidateContext, upstreamUrl);
+  expect(deleted).toBeTrue();
+
+  // Should be gone
+  entry = await cache.get(invalidateContext, upstreamUrl);
+  expect(entry).toBeNull();
+});
+
+tap.test('cache: should invalidate entries matching pattern', async () => {
+  const upstreamUrl = 'https://pattern.example.com';
+
+  // Add multiple entries
+  for (const name of ['pattern-a', 'pattern-b', 'other-c']) {
+    const context = createFetchContext({ resource: name });
+    await cache.set(
+      context,
+      Buffer.from(`data for ${name}`),
+      'text/plain',
+      {},
+      'pattern-upstream',
+      upstreamUrl
+    );
+  }
+
+  // Invalidate entries matching 'pattern-*'
+  const count = await cache.invalidatePattern(/pattern-/);
+  expect(count).toBeGreaterThanOrEqual(2);
+
+  // pattern-a should be gone
+  const entryA = await cache.get(createFetchContext({ resource: 'pattern-a' }), upstreamUrl);
+  expect(entryA).toBeNull();
+
+  // other-c should still exist
+  const entryC = await cache.get(createFetchContext({ resource: 'other-c' }), upstreamUrl);
+  expect(entryC).toBeTruthy();
+});
+
+// ============================================================================
+// Cleanup
+// ============================================================================
+
+tap.test('cleanup: should stop cache and clean up bucket', async () => {
+  if (cache) {
+    cache.stop();
+  }
+
+  // Clean up test bucket
+  if (s3Bucket) {
+    try {
+      const files = await s3Bucket.fastList({});
+      for (const file of files) {
+        await s3Bucket.fastRemove({ path: file.name });
+      }
+      await smartBucket.removeBucket(bucketName);
+    } catch {
+      // Ignore cleanup errors
+    }
+  }
+});
+
+export default tap.start();
diff --git a/ts/00_commitinfo_data.ts b/ts/00_commitinfo_data.ts
index 3cc6f6c..81ddc3d 100644
--- a/ts/00_commitinfo_data.ts
+++ b/ts/00_commitinfo_data.ts
@@ -3,6 +3,6 @@
  */
 export const commitinfo = {
   name: '@push.rocks/smartregistry',
-  version: '2.5.0',
+  version: '2.6.0',
   description: 'A composable TypeScript library implementing OCI, NPM, Maven, Cargo, Composer, PyPI, and RubyGems registries for building unified container and package registries'
 }