diff --git a/.kokoro/samples/python3.6/periodic-head.cfg b/.kokoro/samples/python3.6/periodic-head.cfg
new file mode 100644
index 00000000..f9cfcd33
--- /dev/null
+++ b/.kokoro/samples/python3.6/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-pubsub/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/samples/python3.7/periodic-head.cfg b/.kokoro/samples/python3.7/periodic-head.cfg
new file mode 100644
index 00000000..f9cfcd33
--- /dev/null
+++ b/.kokoro/samples/python3.7/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-pubsub/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/samples/python3.8/periodic-head.cfg b/.kokoro/samples/python3.8/periodic-head.cfg
new file mode 100644
index 00000000..f9cfcd33
--- /dev/null
+++ b/.kokoro/samples/python3.8/periodic-head.cfg
@@ -0,0 +1,11 @@
+# Format: //devtools/kokoro/config/proto/build.proto
+
+env_vars: {
+    key: "INSTALL_LIBRARY_FROM_SOURCE"
+    value: "True"
+}
+
+env_vars: {
+    key: "TRAMPOLINE_BUILD_FILE"
+    value: "github/python-pubsub/.kokoro/test-samples-against-head.sh"
+}
diff --git a/.kokoro/test-samples-against-head.sh b/.kokoro/test-samples-against-head.sh
new file mode 100755
index 00000000..3a572090
--- /dev/null
+++ b/.kokoro/test-samples-against-head.sh
@@ -0,0 +1,28 @@
+#!/bin/bash
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# A customized test runner for samples.
+#
+# For periodic builds, you can specify this file for testing against head.
+
+# `-e` enables the script to automatically fail when a command fails
+# `-o pipefail` sets the exit code to the rightmost comment to exit with a non-zero
+set -eo pipefail
+# Enables `**` to include files nested inside sub-folders
+shopt -s globstar
+
+cd github/python-dialogflow-cx
+
+exec .kokoro/test-samples-impl.sh
diff --git a/.kokoro/test-samples-impl.sh b/.kokoro/test-samples-impl.sh
new file mode 100755
index 00000000..cf5de74c
--- /dev/null
+++ b/.kokoro/test-samples-impl.sh
@@ -0,0 +1,102 @@
+#!/bin/bash
+# Copyright 2021 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+
+# `-e` enables the script to automatically fail when a command fails
+# `-o pipefail` sets the exit code to the rightmost comment to exit with a non-zero
+set -eo pipefail
+# Enables `**` to include files nested inside sub-folders
+shopt -s globstar
+
+# Exit early if samples directory doesn't exist
+if [ ! -d "./samples" ]; then
+  echo "No tests run. `./samples` not found"
+  exit 0
+fi
+
+# Disable buffering, so that the logs stream through.
+export PYTHONUNBUFFERED=1
+
+# Debug: show build environment
+env | grep KOKORO
+
+# Install nox
+python3.6 -m pip install --upgrade --quiet nox
+
+# Use secrets acessor service account to get secrets
+if [[ -f "${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" ]]; then
+    gcloud auth activate-service-account \
+	   --key-file="${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" \
+	   --project="cloud-devrel-kokoro-resources"
+fi
+
+# This script will create 3 files:
+# - testing/test-env.sh
+# - testing/service-account.json
+# - testing/client-secrets.json
+./scripts/decrypt-secrets.sh
+
+source ./testing/test-env.sh
+export GOOGLE_APPLICATION_CREDENTIALS=$(pwd)/testing/service-account.json
+
+# For cloud-run session, we activate the service account for gcloud sdk.
+gcloud auth activate-service-account \
+       --key-file "${GOOGLE_APPLICATION_CREDENTIALS}"
+
+export GOOGLE_CLIENT_SECRETS=$(pwd)/testing/client-secrets.json
+
+echo -e "\n******************** TESTING PROJECTS ********************"
+
+# Switch to 'fail at end' to allow all tests to complete before exiting.
+set +e
+# Use RTN to return a non-zero value if the test fails.
+RTN=0
+ROOT=$(pwd)
+# Find all requirements.txt in the samples directory (may break on whitespace).
+for file in samples/**/requirements.txt; do
+    cd "$ROOT"
+    # Navigate to the project folder.
+    file=$(dirname "$file")
+    cd "$file"
+
+    echo "------------------------------------------------------------"
+    echo "- testing $file"
+    echo "------------------------------------------------------------"
+
+    # Use nox to execute the tests for the project.
+    python3.6 -m nox -s "$RUN_TESTS_SESSION"
+    EXIT=$?
+
+    # If this is a periodic build, send the test log to the FlakyBot.
+    # See https://github.com/googleapis/repo-automation-bots/tree/master/packages/flakybot.
+    if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
+      chmod +x $KOKORO_GFILE_DIR/linux_amd64/flakybot
+      $KOKORO_GFILE_DIR/linux_amd64/flakybot
+    fi
+
+    if [[ $EXIT -ne 0 ]]; then
+      RTN=1
+      echo -e "\n Testing failed: Nox returned a non-zero exit code. \n"
+    else
+      echo -e "\n Testing completed.\n"
+    fi
+
+done
+cd "$ROOT"
+
+# Workaround for Kokoro permissions issue: delete secrets
+rm testing/{test-env.sh,client-secrets.json,service-account.json}
+
+exit "$RTN"
diff --git a/.kokoro/test-samples.sh b/.kokoro/test-samples.sh
index 006d51e0..b9f3a6e6 100755
--- a/.kokoro/test-samples.sh
+++ b/.kokoro/test-samples.sh
@@ -13,6 +13,10 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+# The default test runner for samples.
+#
+# For periodic builds, we rewinds the repo to the latest release, and
+# run test-samples-impl.sh.
 
 # `-e` enables the script to automatically fail when a command fails
 # `-o pipefail` sets the exit code to the rightmost comment to exit with a non-zero
@@ -24,87 +28,19 @@ cd github/python-dialogflow-cx
 
 # Run periodic samples tests at latest release
 if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
+    # preserving the test runner implementation.
+    cp .kokoro/test-samples-impl.sh "${TMPDIR}/test-samples-impl.sh"
+    echo "--- IMPORTANT IMPORTANT IMPORTANT ---"
+    echo "Now we rewind the repo back to the latest release..."
     LATEST_RELEASE=$(git describe --abbrev=0 --tags)
     git checkout $LATEST_RELEASE
-fi
-
-# Exit early if samples directory doesn't exist
-if [ ! -d "./samples" ]; then
-  echo "No tests run. `./samples` not found"
-  exit 0
-fi
-
-# Disable buffering, so that the logs stream through.
-export PYTHONUNBUFFERED=1
-
-# Debug: show build environment
-env | grep KOKORO
-
-# Install nox
-python3.6 -m pip install --upgrade --quiet nox
-
-# Use secrets acessor service account to get secrets
-if [[ -f "${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" ]]; then
-    gcloud auth activate-service-account \
-	   --key-file="${KOKORO_GFILE_DIR}/secrets_viewer_service_account.json" \
-	   --project="cloud-devrel-kokoro-resources"
-fi
-
-# This script will create 3 files:
-# - testing/test-env.sh
-# - testing/service-account.json
-# - testing/client-secrets.json
-./scripts/decrypt-secrets.sh
-
-source ./testing/test-env.sh
-export GOOGLE_APPLICATION_CREDENTIALS=$(pwd)/testing/service-account.json
-
-# For cloud-run session, we activate the service account for gcloud sdk.
-gcloud auth activate-service-account \
-       --key-file "${GOOGLE_APPLICATION_CREDENTIALS}"
-
-export GOOGLE_CLIENT_SECRETS=$(pwd)/testing/client-secrets.json
-
-echo -e "\n******************** TESTING PROJECTS ********************"
-
-# Switch to 'fail at end' to allow all tests to complete before exiting.
-set +e
-# Use RTN to return a non-zero value if the test fails.
-RTN=0
-ROOT=$(pwd)
-# Find all requirements.txt in the samples directory (may break on whitespace).
-for file in samples/**/requirements.txt; do
-    cd "$ROOT"
-    # Navigate to the project folder.
-    file=$(dirname "$file")
-    cd "$file"
-
-    echo "------------------------------------------------------------"
-    echo "- testing $file"
-    echo "------------------------------------------------------------"
-
-    # Use nox to execute the tests for the project.
-    python3.6 -m nox -s "$RUN_TESTS_SESSION"
-    EXIT=$?
-
-    # If this is a periodic build, send the test log to the FlakyBot.
-    # See https://github.com/googleapis/repo-automation-bots/tree/master/packages/flakybot.
-    if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
-      chmod +x $KOKORO_GFILE_DIR/linux_amd64/flakybot
-      $KOKORO_GFILE_DIR/linux_amd64/flakybot
+    echo "The current head is: "
+    echo $(git rev-parse --verify HEAD)
+    echo "--- IMPORTANT IMPORTANT IMPORTANT ---"
+    # move back the test runner implementation if there's no file.
+    if [ ! -f .kokoro/test-samples-impl.sh ]; then
+	cp "${TMPDIR}/test-samples-impl.sh" .kokoro/test-samples-impl.sh
     fi
+fi
 
-    if [[ $EXIT -ne 0 ]]; then
-      RTN=1
-      echo -e "\n Testing failed: Nox returned a non-zero exit code. \n"
-    else
-      echo -e "\n Testing completed.\n"
-    fi
-
-done
-cd "$ROOT"
-
-# Workaround for Kokoro permissions issue: delete secrets
-rm testing/{test-env.sh,client-secrets.json,service-account.json}
-
-exit "$RTN"
+exec .kokoro/test-samples-impl.sh
diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index a9024b15..32302e48 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -12,6 +12,6 @@ repos:
     hooks:
     - id: black
 -   repo: https://gitlab.com/pycqa/flake8
-    rev: 3.8.4
+    rev: 3.9.0
     hooks:
     - id: flake8
diff --git a/dialogflow-cx-v3beta1-py.tar.gz b/dialogflow-cx-v3beta1-py.tar.gz
new file mode 100644
index 00000000..be178428
Binary files /dev/null and b/dialogflow-cx-v3beta1-py.tar.gz differ
diff --git a/google/cloud/dialogflowcx_v3/__init__.py b/google/cloud/dialogflowcx_v3/__init__.py
index 589dcd20..f328b094 100644
--- a/google/cloud/dialogflowcx_v3/__init__.py
+++ b/google/cloud/dialogflowcx_v3/__init__.py
@@ -251,7 +251,6 @@
     "DetectIntentResponse",
     "DtmfInput",
     "EntityType",
-    "EntityTypesClient",
     "Environment",
     "EnvironmentsClient",
     "EventHandler",
@@ -293,6 +292,7 @@
     "IntentCoverage",
     "IntentInput",
     "IntentView",
+    "IntentsClient",
     "ListAgentsRequest",
     "ListAgentsResponse",
     "ListEntityTypesRequest",
@@ -399,5 +399,5 @@
     "WebhookRequest",
     "WebhookResponse",
     "WebhooksClient",
-    "IntentsClient",
+    "EntityTypesClient",
 )
diff --git a/google/cloud/dialogflowcx_v3beta1/__init__.py b/google/cloud/dialogflowcx_v3beta1/__init__.py
index 3167e84a..5e50202b 100644
--- a/google/cloud/dialogflowcx_v3beta1/__init__.py
+++ b/google/cloud/dialogflowcx_v3beta1/__init__.py
@@ -211,6 +211,7 @@
 __all__ = (
     "Agent",
     "AgentValidationResult",
+    "AgentsClient",
     "AudioEncoding",
     "AudioInput",
     "BatchDeleteTestCasesRequest",
@@ -252,7 +253,6 @@
     "EntityType",
     "EntityTypesClient",
     "Environment",
-    "EnvironmentsClient",
     "EventHandler",
     "EventInput",
     "Experiment",
@@ -399,5 +399,5 @@
     "WebhookRequest",
     "WebhookResponse",
     "WebhooksClient",
-    "AgentsClient",
+    "EnvironmentsClient",
 )
diff --git a/noxfile.py b/noxfile.py
index 0ad24c69..0f27c1ff 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -18,6 +18,7 @@
 
 from __future__ import absolute_import
 import os
+import pathlib
 import shutil
 
 import nox
@@ -30,6 +31,8 @@
 SYSTEM_TEST_PYTHON_VERSIONS = ["3.8"]
 UNIT_TEST_PYTHON_VERSIONS = ["3.6", "3.7", "3.8", "3.9"]
 
+CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
+
 # 'docfx' is excluded since it only needs to run in 'docs-presubmit'
 nox.options.sessions = [
     "unit",
@@ -41,6 +44,9 @@
     "docs",
 ]
 
+# Error if a python version is missing
+nox.options.error_on_missing_interpreters = True
+
 
 @nox.session(python=DEFAULT_PYTHON_VERSION)
 def lint(session):
@@ -81,13 +87,15 @@ def lint_setup_py(session):
 
 def default(session):
     # Install all test dependencies, then install this package in-place.
-    session.install("asyncmock", "pytest-asyncio")
 
-    session.install(
-        "mock", "pytest", "pytest-cov",
+    constraints_path = str(
+        CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
+    session.install("asyncmock", "pytest-asyncio", "-c", constraints_path)
 
-    session.install("-e", ".")
+    session.install("mock", "pytest", "pytest-cov", "-c", constraints_path)
+
+    session.install("-e", ".", "-c", constraints_path)
 
     # Run py.test against the unit tests.
     session.run(
@@ -114,6 +122,9 @@ def unit(session):
 @nox.session(python=SYSTEM_TEST_PYTHON_VERSIONS)
 def system(session):
     """Run the system test suite."""
+    constraints_path = str(
+        CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
+    )
     system_test_path = os.path.join("tests", "system.py")
     system_test_folder_path = os.path.join("tests", "system")
 
@@ -138,10 +149,8 @@ def system(session):
 
     # Install all test dependencies, then install this package into the
     # virtualenv's dist-packages.
-    session.install(
-        "mock", "pytest", "google-cloud-testutils",
-    )
-    session.install("-e", ".")
+    session.install("mock", "pytest", "google-cloud-testutils", "-c", constraints_path)
+    session.install("-e", ".", "-c", constraints_path)
 
     # Run py.test against the system tests.
     if system_test_exists:
@@ -201,9 +210,7 @@ def docfx(session):
     """Build the docfx yaml files for this library."""
 
     session.install("-e", ".")
-    # sphinx-docfx-yaml supports up to sphinx version 1.5.5.
-    # https://github.com/docascode/sphinx-docfx-yaml/issues/97
-    session.install("sphinx==1.5.5", "alabaster", "recommonmark", "sphinx-docfx-yaml")
+    session.install("sphinx", "alabaster", "recommonmark", "gcp-sphinx-docfx-yaml")
 
     shutil.rmtree(os.path.join("docs", "_build"), ignore_errors=True)
     session.run(
diff --git a/renovate.json b/renovate.json
index 4fa94931..f08bc22c 100644
--- a/renovate.json
+++ b/renovate.json
@@ -1,5 +1,6 @@
 {
   "extends": [
     "config:base",  ":preserveSemverRanges"
-  ]
+  ],
+  "ignorePaths": [".pre-commit-config.yaml"]
 }
diff --git a/synth.metadata b/synth.metadata
index 50c9c203..d3781971 100644
--- a/synth.metadata
+++ b/synth.metadata
@@ -4,7 +4,7 @@
       "git": {
         "name": ".",
         "remote": "https://github.com/googleapis/python-dialogflow-cx.git",
-        "sha": "aeb1ce98ddba2dd4f3ccc874608d6127ccaee3df"
+        "sha": "3440f186cd879fd4ddc9b3442bf857a4f286698e"
       }
     },
     {
@@ -19,14 +19,14 @@
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "6056faa36b3ab941a56f71eab8164e78af998844"
+        "sha": "4501974ad08b5d693311457e2ea4ce845676e329"
       }
     },
     {
       "git": {
         "name": "synthtool",
         "remote": "https://github.com/googleapis/synthtool.git",
-        "sha": "6056faa36b3ab941a56f71eab8164e78af998844"
+        "sha": "4501974ad08b5d693311457e2ea4ce845676e329"
       }
     }
   ],
@@ -83,16 +83,21 @@
     ".kokoro/samples/lint/presubmit.cfg",
     ".kokoro/samples/python3.6/common.cfg",
     ".kokoro/samples/python3.6/continuous.cfg",
+    ".kokoro/samples/python3.6/periodic-head.cfg",
     ".kokoro/samples/python3.6/periodic.cfg",
     ".kokoro/samples/python3.6/presubmit.cfg",
     ".kokoro/samples/python3.7/common.cfg",
     ".kokoro/samples/python3.7/continuous.cfg",
+    ".kokoro/samples/python3.7/periodic-head.cfg",
     ".kokoro/samples/python3.7/periodic.cfg",
     ".kokoro/samples/python3.7/presubmit.cfg",
     ".kokoro/samples/python3.8/common.cfg",
     ".kokoro/samples/python3.8/continuous.cfg",
+    ".kokoro/samples/python3.8/periodic-head.cfg",
     ".kokoro/samples/python3.8/periodic.cfg",
     ".kokoro/samples/python3.8/presubmit.cfg",
+    ".kokoro/test-samples-against-head.sh",
+    ".kokoro/test-samples-impl.sh",
     ".kokoro/test-samples.sh",
     ".kokoro/trampoline.sh",
     ".kokoro/trampoline_v2.sh",
@@ -102,6 +107,7 @@
     "CONTRIBUTING.rst",
     "LICENSE",
     "MANIFEST.in",
+    "dialogflow-cx-v3beta1-py.tar.gz",
     "docs/_static/custom.css",
     "docs/_templates/layout.html",
     "docs/conf.py",