diff --git a/package.json b/package.json
index e20531c9..ff61339c 100644
--- a/package.json
+++ b/package.json
@@ -19,17 +19,12 @@
     "docs-test": "linkinator docs",
     "compile:oss": "tsc -p tsconfig.json.oss",
     "fix": "gts fix",
-    "test": "npm run test:src && npm run test:test",
-    "test": "npm run test:legacy:src && npm run test:legacy:test",
-    "test:src": "npm run test:legacy:src",
-    "test:test": "npm run test:legacy:test",
-    "test:system": "npm run test:legacy:system && npm run test:genai:system",
-    "test:legacy:src": "jasmine build/vertexai/src/functions/test/*_test.js build/vertexai/src/models/test/*_test.js --reporter=test/spec/reporter.js",
-    "test:legacy:test": "jasmine build/vertexai/test/*_test.js --reporter=test/spec/reporter.js",
-    "test:legacy:system": "jasmine build/vertexai/system_test/*_test.js --reporter=test/spec/reporter.js",
-    "test:genai:system": "jasmine build/system_test/*_test.js --reporter=test/spec/reporter.js",
-    "lint": "ESLINT_USE_FLAT_CONFIG=true eslint src/genai --no-ignore --config src/genai/eslint.config.mjs",
-    "format": "prettier 'src/genai/**/*.ts' 'src/genai/**/*.mjs' --write",
+    "test": "npm run test:unit",
+    "test:unit": "jasmine build/test/unit/*_test.js --reporter=test/spec/reporter.js",
+    "test:system": "jasmine build/system_test/*_test.js --reporter=test/spec/reporter.js",
+    "test:replays": "jasmine build/test/replays/*_test.js --reporter=test/spec/reporter.js",
+    "lint": "ESLINT_USE_FLAT_CONFIG=true eslint src --no-ignore --config src/eslint.config.mjs",
+    "format": "prettier 'src/**/*.ts' 'src/**/*.mjs' --write",
     "clean-js-files": "find . -type f -name \"*.js\" -exec rm -f {} +",
     "clean-js-map-files": "find . -type f -name \"*.js.map\" -exec rm -f {} +",
     "postpack": "if [ \"${CLEAN}\" ]; then npm run clean-after-pack; fi",
diff --git a/src/genai/.prettierignore b/src/.prettierignore
similarity index 100%
rename from src/genai/.prettierignore
rename to src/.prettierignore
diff --git a/src/genai/.prettierrc b/src/.prettierrc
similarity index 100%
rename from src/genai/.prettierrc
rename to src/.prettierrc
diff --git a/src/genai/_internal_types.ts b/src/_internal_types.ts
similarity index 100%
rename from src/genai/_internal_types.ts
rename to src/_internal_types.ts
diff --git a/src/genai/agentengines.ts b/src/agentengines.ts
similarity index 100%
rename from src/genai/agentengines.ts
rename to src/agentengines.ts
diff --git a/src/genai/client.ts b/src/client.ts
similarity index 100%
rename from src/genai/client.ts
rename to src/client.ts
diff --git a/src/genai/converters/_agentengines_converters.ts b/src/converters/_agentengines_converters.ts
similarity index 100%
rename from src/genai/converters/_agentengines_converters.ts
rename to src/converters/_agentengines_converters.ts
diff --git a/src/genai/converters/_memories_converters.ts b/src/converters/_memories_converters.ts
similarity index 100%
rename from src/genai/converters/_memories_converters.ts
rename to src/converters/_memories_converters.ts
diff --git a/src/genai/converters/_memoryrevisions_converters.ts b/src/converters/_memoryrevisions_converters.ts
similarity index 100%
rename from src/genai/converters/_memoryrevisions_converters.ts
rename to src/converters/_memoryrevisions_converters.ts
diff --git a/src/genai/converters/_sandboxes_converters.ts b/src/converters/_sandboxes_converters.ts
similarity index 100%
rename from src/genai/converters/_sandboxes_converters.ts
rename to src/converters/_sandboxes_converters.ts
diff --git a/src/genai/converters/_sessionevents_converters.ts b/src/converters/_sessionevents_converters.ts
similarity index 100%
rename from src/genai/converters/_sessionevents_converters.ts
rename to src/converters/_sessionevents_converters.ts
diff --git a/src/genai/converters/_sessions_converters.ts b/src/converters/_sessions_converters.ts
similarity index 100%
rename from src/genai/converters/_sessions_converters.ts
rename to src/converters/_sessions_converters.ts
diff --git a/src/genai/eslint.config.mjs b/src/eslint.config.mjs
similarity index 100%
rename from src/genai/eslint.config.mjs
rename to src/eslint.config.mjs
diff --git a/src/index.ts b/src/index.ts
index a3a6b4ca..98222d7a 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -15,8 +15,5 @@
  * limitations under the License.
  */
 
-export {VertexAI} from '../vertexai/src/vertex_ai';
-export {Client} from './genai/client';
-
-export * from '../vertexai/src/types';
-export * from '../vertexai/src/models';
+export {Client} from './client';
+export * from './types';
diff --git a/src/genai/memories.ts b/src/memories.ts
similarity index 100%
rename from src/genai/memories.ts
rename to src/memories.ts
diff --git a/src/genai/memoryrevisions.ts b/src/memoryrevisions.ts
similarity index 100%
rename from src/genai/memoryrevisions.ts
rename to src/memoryrevisions.ts
diff --git a/src/genai/sandboxes.ts b/src/sandboxes.ts
similarity index 100%
rename from src/genai/sandboxes.ts
rename to src/sandboxes.ts
diff --git a/src/genai/sessionevents.ts b/src/sessionevents.ts
similarity index 100%
rename from src/genai/sessionevents.ts
rename to src/sessionevents.ts
diff --git a/src/genai/sessions.ts b/src/sessions.ts
similarity index 100%
rename from src/genai/sessions.ts
rename to src/sessions.ts
diff --git a/src/genai/types.ts b/src/types.ts
similarity index 100%
rename from src/genai/types.ts
rename to src/types.ts
diff --git a/src/genai/types/common.ts b/src/types/common.ts
similarity index 100%
rename from src/genai/types/common.ts
rename to src/types/common.ts
diff --git a/system_test/agent_engine_e2e_test.ts b/system_test/agent_engine_e2e_test.ts
index 963773b8..f9e6f64a 100644
--- a/system_test/agent_engine_e2e_test.ts
+++ b/system_test/agent_engine_e2e_test.ts
@@ -4,7 +4,7 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-import {Client} from '../src/genai/client';
+import {Client} from '../src/client';
 
 const PROJECT = process.env['GCLOUD_PROJECT'];
 const LOCATION = 'us-central1';
diff --git a/test/genai/_replay_client.ts b/test/replays/_replay_client.ts
similarity index 99%
rename from test/genai/_replay_client.ts
rename to test/replays/_replay_client.ts
index b61a89cc..a0129418 100644
--- a/test/genai/_replay_client.ts
+++ b/test/replays/_replay_client.ts
@@ -8,7 +8,7 @@ import {Pager} from '@google/genai';
 import * as fs from 'fs';
 import * as path from 'path';
 
-import {Client} from '../../src/genai/client.js';
+import {Client} from '../../src/client.js';
 
 /**
  * Bypass real credential fetching during replay.
diff --git a/test/genai/agentengines_memories_test.ts b/test/replays/agentengines_memories_test.ts
similarity index 100%
rename from test/genai/agentengines_memories_test.ts
rename to test/replays/agentengines_memories_test.ts
diff --git a/test/genai/agentengines_sandboxes_test.ts b/test/replays/agentengines_sandboxes_test.ts
similarity index 98%
rename from test/genai/agentengines_sandboxes_test.ts
rename to test/replays/agentengines_sandboxes_test.ts
index cec26600..2be3f0d7 100644
--- a/test/genai/agentengines_sandboxes_test.ts
+++ b/test/replays/agentengines_sandboxes_test.ts
@@ -8,7 +8,7 @@ import 'jasmine';
 
 import {NodeAuth} from '@google/genai/vertex_internal';
 
-import * as types from '../../src/genai/types.js';
+import * as types from '../../src/types.js';
 
 import {ReplayClient} from './_replay_client.js';
 
diff --git a/test/genai/agentengines_sessions_test.ts b/test/replays/agentengines_sessions_test.ts
similarity index 100%
rename from test/genai/agentengines_sessions_test.ts
rename to test/replays/agentengines_sessions_test.ts
diff --git a/test/genai/agentengines_test.ts b/test/replays/agentengines_test.ts
similarity index 100%
rename from test/genai/agentengines_test.ts
rename to test/replays/agentengines_test.ts
diff --git a/test/replays/run_replay_tests.sh b/test/replays/run_replay_tests.sh
new file mode 100755
index 00000000..9d4f726e
--- /dev/null
+++ b/test/replays/run_replay_tests.sh
@@ -0,0 +1,65 @@
+#!/bin/bash
+
+# This script runs replay tests for the Vertex SDK JS GenAI modules.
+# It is intended to be used from the google3 directory of a CitC client.
+#
+# Example:
+#   ./third_party/javascript/node_modules/vertexai/test/genai/run_replay_tests.sh
+
+START_DIR=$(pwd)
+
+if [[ "$START_DIR" != */google3 ]]; then
+    echo "Error: This script must be run from your client's '/google3' directory."
+    echo "Your current directory is: $START_DIR"
+    exit 1
+fi
+
+export GOOGLE_GENAI_REPLAYS_DIRECTORY="$START_DIR/google/cloud/aiplatform/sdk/genai/replays/tests/vertex_sdk_genai_replays/"
+
+if [ ! -d "$GOOGLE_GENAI_REPLAYS_DIRECTORY" ]; then
+    echo "Error: Replays directory not found at $GOOGLE_GENAI_REPLAYS_DIRECTORY"
+    exit 1
+fi
+
+PARSED_ARGS=$(getopt -o "" -l "mode:" -- "$@")
+
+if [ $? -ne 0 ]; then
+    echo "Error: Failed to parse command line arguments." >&2
+    exit 1
+fi
+
+eval set -- "$PARSED_ARGS"
+MODE_VALUE="replay"
+
+while true; do
+    case "$1" in
+        --mode)
+            MODE_VALUE="$2"
+            shift 2
+            ;;
+        --)
+            shift
+            break
+            ;;
+        *)
+            echo "Internal error: Unrecognized arg option: '$1'" >&2
+            exit 1
+            ;;
+    esac
+done
+
+if [ "$MODE_VALUE" != "replay" ]; then
+    echo "Error: The JS SDK currently only supports --mode replay."
+    exit 1
+fi
+
+echo "Running JS GenAI replay tests via blaze..."
+
+blaze test --test_strategy=local \
+  --test_env=GOOGLE_GENAI_REPLAYS_DIRECTORY="$GOOGLE_GENAI_REPLAYS_DIRECTORY" \
+  --test_output=errors \
+  //third_party/javascript/node_modules/vertexai/test:genai_modules_replay_tests
+
+EXIT_CODE=$?
+echo "Tests completed with exit code: $EXIT_CODE."
+exit $EXIT_CODE
diff --git a/test/genai/sessionevents_test.ts b/test/replays/sessionevents_test.ts
similarity index 100%
rename from test/genai/sessionevents_test.ts
rename to test/replays/sessionevents_test.ts
diff --git a/test/replays/test_env.js b/test/replays/test_env.js
new file mode 100644
index 00000000..2b7b4e13
--- /dev/null
+++ b/test/replays/test_env.js
@@ -0,0 +1,24 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+const path = require('path');
+
+module.exports = {
+  beforeJasmine: () => {
+    process.env['GOOGLE_CLOUD_PROJECT'] = 'vertex-sdk-dev';
+    process.env['GOOGLE_CLOUD_LOCATION'] = 'us-central1';
+
+    if (process.env['RUNFILES']) {
+      process.env['GOOGLE_GENAI_REPLAYS_DIRECTORY'] = path.join(
+          process.env['RUNFILES'],
+          'google3/google/cloud/aiplatform/sdk/genai/replays/tests/vertex_sdk_genai_replays'
+      );
+    }
+
+    return Promise.resolve();
+  },
+  afterJasmine: (failureReason) => Promise.resolve(failureReason),
+};
diff --git a/test/unit/client_test.ts b/test/unit/client_test.ts
new file mode 100644
index 00000000..ee9e08ab
--- /dev/null
+++ b/test/unit/client_test.ts
@@ -0,0 +1,30 @@
+import {AgentEngines} from '../../src/agentengines';
+import {Client} from '../../src/client';
+
+describe('GenAI Client Instantiation', () => {
+  const options = {
+    project: 'test-project',
+    location: 'us-central1',
+  };
+
+  it('should initialize with provided project and location', () => {
+    const client = new Client(options);
+    expect(client).toBeDefined();
+  });
+
+  it('should expose agentEnginesInternal as an instance of AgentEngines',
+     () => {
+       const client = new Client(options);
+       // This will log an experimental warning.
+       expect(client.agentEnginesInternal).toBeDefined();
+       expect(client.agentEnginesInternal instanceof AgentEngines).toBe(true);
+     });
+
+  it('should correctly initialize AgentEngines submodules', () => {
+    const client = new Client(options);
+    const ae = client.agentEnginesInternal;
+    expect(ae.sessions).toBeDefined();
+    expect(ae.sandboxes).toBeDefined();
+    expect(ae.memories).toBeDefined();
+  });
+});
diff --git a/vertexai/package.json b/vertexai/package.json
index e20531c9..ff61339c 100644
--- a/vertexai/package.json
+++ b/vertexai/package.json
@@ -19,17 +19,12 @@
     "docs-test": "linkinator docs",
     "compile:oss": "tsc -p tsconfig.json.oss",
     "fix": "gts fix",
-    "test": "npm run test:src && npm run test:test",
-    "test": "npm run test:legacy:src && npm run test:legacy:test",
-    "test:src": "npm run test:legacy:src",
-    "test:test": "npm run test:legacy:test",
-    "test:system": "npm run test:legacy:system && npm run test:genai:system",
-    "test:legacy:src": "jasmine build/vertexai/src/functions/test/*_test.js build/vertexai/src/models/test/*_test.js --reporter=test/spec/reporter.js",
-    "test:legacy:test": "jasmine build/vertexai/test/*_test.js --reporter=test/spec/reporter.js",
-    "test:legacy:system": "jasmine build/vertexai/system_test/*_test.js --reporter=test/spec/reporter.js",
-    "test:genai:system": "jasmine build/system_test/*_test.js --reporter=test/spec/reporter.js",
-    "lint": "ESLINT_USE_FLAT_CONFIG=true eslint src/genai --no-ignore --config src/genai/eslint.config.mjs",
-    "format": "prettier 'src/genai/**/*.ts' 'src/genai/**/*.mjs' --write",
+    "test": "npm run test:unit",
+    "test:unit": "jasmine build/test/unit/*_test.js --reporter=test/spec/reporter.js",
+    "test:system": "jasmine build/system_test/*_test.js --reporter=test/spec/reporter.js",
+    "test:replays": "jasmine build/test/replays/*_test.js --reporter=test/spec/reporter.js",
+    "lint": "ESLINT_USE_FLAT_CONFIG=true eslint src --no-ignore --config src/eslint.config.mjs",
+    "format": "prettier 'src/**/*.ts' 'src/**/*.mjs' --write",
     "clean-js-files": "find . -type f -name \"*.js\" -exec rm -f {} +",
     "clean-js-map-files": "find . -type f -name \"*.js.map\" -exec rm -f {} +",
     "postpack": "if [ \"${CLEAN}\" ]; then npm run clean-after-pack; fi",