From 06b896757370ad5f21db9f7ec8d1ae40a714ba2a Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Fri, 26 Jun 2026 16:39:20 +0000
Subject: [PATCH 01/22] tests: add testing for Python 3.15

---
 .github/workflows/unittest.yml                | 150 ++++++++++++++++--
 .kokoro/presubmit/system.cfg                  |   2 +
 ci/get_batches.py                             |  81 ++++++++++
 ci/run_conditional_tests.sh                   |  47 +++++-
 ci/run_single_test.sh                         |   5 +
 packages/bigframes/mypy.ini                   |  49 ------
 packages/bigframes/noxfile.py                 |   6 +-
 packages/bigquery-magics/noxfile.py           |   5 +
 .../testing/constraints-3.15.txt              |   0
 packages/db-dtypes/noxfile.py                 |   3 +
 .../db-dtypes/testing/constraints-3.15.txt    |   0
 packages/django-google-spanner/noxfile.py     |   1 +
 .../testing/constraints-3.15.txt              |   0
 packages/gcp-sphinx-docfx-yaml/noxfile.py     |   4 +-
 packages/google-api-core/noxfile.py           |   7 +-
 .../testing/constraints-3.15.txt              |   0
 packages/google-auth-httplib2/noxfile.py      |   1 +
 .../testing/constraints-3.15.txt              |   0
 packages/google-auth-oauthlib/noxfile.py      |   1 +
 .../testing/constraints-3.15.txt              |   0
 packages/google-auth/noxfile.py               |   6 +-
 .../google-auth/testing/constraints-3.15.txt  |   0
 .../noxfile.py                                |   3 +-
 .../testing/constraints-3.15.txt              |   0
 packages/google-cloud-audit-log/noxfile.py    |   3 +-
 .../testing/constraints-3.15.txt              |   0
 packages/google-cloud-bigquery/.coveragerc    |   2 +-
 packages/google-cloud-bigquery/noxfile.py     |   6 +-
 .../testing/constraints-3.15.txt              |   0
 packages/google-cloud-bigtable/noxfile.py     |   3 +
 packages/google-cloud-core/noxfile.py         |   1 +
 .../testing/constraints-3.15.txt              |   0
 packages/google-cloud-dns/noxfile.py          |   1 +
 .../testing/constraints-3.15.txt              |   0
 .../noxfile.py                                |   5 +
 .../google-cloud-documentai-toolbox/setup.py  |   5 +-
 .../testing/constraints-3.15.txt              |  13 ++
 packages/google-cloud-ndb/noxfile.py          |   2 +-
 .../testing/constraints-3.15.txt              |   8 +
 .../google-cloud-runtimeconfig/noxfile.py     |   1 +
 .../testing/constraints-3.15.txt              |   0
 .../noxfile.py                                |   6 +-
 .../testing/constraints-3.15.txt              |   4 +
 packages/google-cloud-storage/noxfile.py      |   4 +
 packages/google-cloud-testutils/noxfile.py    |   2 +-
 .../testing/constraints-3.15.txt              |   0
 packages/google-resumable-media/noxfile.py    |   2 +-
 .../testing/constraints-3.15.txt              |   0
 packages/googleapis-common-protos/noxfile.py  |   3 +-
 .../testing/constraints-3.15.txt              |   0
 packages/grpc-google-iam-v1/noxfile.py        |   3 +-
 .../testing/constraints-3.15.txt              |   0
 packages/pandas-gbq/noxfile.py                |   6 +
 .../pandas-gbq/testing/constraints-3.15.txt   |   0
 packages/proto-plus/noxfile.py                |   1 +
 .../proto-plus/testing/constraints-3.15.txt   |   0
 56 files changed, 359 insertions(+), 93 deletions(-)
 create mode 100644 ci/get_batches.py
 delete mode 100644 packages/bigframes/mypy.ini
 create mode 100644 packages/bigquery-magics/testing/constraints-3.15.txt
 create mode 100644 packages/db-dtypes/testing/constraints-3.15.txt
 create mode 100644 packages/django-google-spanner/testing/constraints-3.15.txt
 create mode 100644 packages/google-api-core/testing/constraints-3.15.txt
 create mode 100644 packages/google-auth-httplib2/testing/constraints-3.15.txt
 create mode 100644 packages/google-auth-oauthlib/testing/constraints-3.15.txt
 create mode 100644 packages/google-auth/testing/constraints-3.15.txt
 create mode 100644 packages/google-cloud-access-context-manager/testing/constraints-3.15.txt
 create mode 100644 packages/google-cloud-audit-log/testing/constraints-3.15.txt
 create mode 100644 packages/google-cloud-bigquery/testing/constraints-3.15.txt
 create mode 100644 packages/google-cloud-core/testing/constraints-3.15.txt
 create mode 100644 packages/google-cloud-dns/testing/constraints-3.15.txt
 create mode 100644 packages/google-cloud-documentai-toolbox/testing/constraints-3.15.txt
 create mode 100644 packages/google-cloud-ndb/testing/constraints-3.15.txt
 create mode 100644 packages/google-cloud-runtimeconfig/testing/constraints-3.15.txt
 create mode 100644 packages/google-cloud-spanner-dbapi-driver/testing/constraints-3.15.txt
 create mode 100644 packages/google-cloud-testutils/testing/constraints-3.15.txt
 create mode 100644 packages/google-resumable-media/testing/constraints-3.15.txt
 create mode 100644 packages/googleapis-common-protos/testing/constraints-3.15.txt
 create mode 100644 packages/grpc-google-iam-v1/testing/constraints-3.15.txt
 create mode 100644 packages/pandas-gbq/testing/constraints-3.15.txt
 create mode 100644 packages/proto-plus/testing/constraints-3.15.txt

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 392f5ece6270..951bf84200c4 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -12,13 +12,50 @@ name: unittest
 permissions:
   contents: read
 
+# Configurable global environment variables for batching
+env:
+  TEST_ALL_PACKAGES: "false" # Set to "false" to only run tests for packages with a git diff
+  ALL_PYTHON: "['3.10', '3.11', '3.12', '3.13', '3.14', '3.15']"
+  # Force static compilation of libxml2 and libxslt for lxml packages
+  STATIC_DEPS: "true"
+
 jobs:
+  # Dynamic package discovery job to calculate required matrix size automatically
+  python_config:
+    runs-on: ubuntu-latest
+    outputs:
+      all_python: ${{ steps.export.outputs.python_list }}
+    steps:
+      - id: export
+        run: echo "python_list=${{ env.ALL_PYTHON }}" >> "$GITHUB_OUTPUT"
+
+  discover-packages:
+    runs-on: ubuntu-latest
+    outputs:
+      batch-indices: ${{ steps.set-matrix.outputs.indices }}
+    steps:
+    - name: Checkout
+      uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
+      with:
+        persist-credentials: false
+    - name: Setup Python
+      uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6
+      with:
+        python-version: "3.14"
+    - name: Generate Batch Indices
+      id: set-matrix
+      run: |
+        INDICES=$(python -c 'import sys; sys.path.append("ci"); import get_batches; print(get_batches.get_batch_indices())')
+        echo "indices=${INDICES}" >> "$GITHUB_OUTPUT"
+
   unit:
+    name: "unit-run (${{ matrix.python }}, Batch ${{ matrix.batch-index }})"
     runs-on: ubuntu-22.04
+    needs: [python_config, discover-packages]
     strategy:
-      fail-fast: true
       matrix:
-        python: ['3.10', "3.11", "3.12", "3.13", "3.14"]
+        python: ${{ fromJSON(needs.python_config.outputs.all_python) }}
+        batch-index: ${{ fromJson(needs.discover-packages.outputs.batch-indices) }}
     steps:
     - name: Checkout
       uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
@@ -32,30 +69,72 @@ jobs:
       uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6
       with:
         python-version: ${{ matrix.python }}
+        allow-prereleases: true
+    - name: Setup uv
+      uses: astral-sh/setup-uv@v5
+      with:
+        enable-cache: true
+        cache-dependency-glob: 'packages/**/testing/constraints*.txt'
     - name: Install nox
       run: |
-        python -m pip install --upgrade setuptools pip wheel
-        python -m pip install nox
+        uv pip install --system nox nox-uv
+    # Caches compiled wheels locally to prevent building heavy libraries
+    # such as grpcio, which we build from scratch on every run for Python 3.15+.
+    # Follow https://github.com/grpc/grpc/issues/41010 for updates.
+    - name: Cache Built Python 3.15 Wheels
+      if: matrix.python == '3.15'
+      uses: actions/cache@v4
+      with:
+        path: .uv-wheel-cache
+        key: ${{ runner.os }}-uv-wheels-3.15-${{ hashFiles('packages/**/testing/constraints*.txt') }}
+        restore-keys: |
+          ${{ runner.os }}-uv-wheels-3.15-
     - name: Run unit tests
+      id: run-tests
       env:
-        COVERAGE_FILE: ${{ github.workspace }}/.coverage-${{ matrix.python }}
-        BUILD_TYPE: presubmit
+        COVERAGE_FILE: ${{ github.workspace }}/.coverage-${{ matrix.python }}-${{ matrix.batch-index }}
+        # Dynamically set BUILD_TYPE to an empty string to skip the diff calculation if TEST_ALL_PACKAGES is true
+        BUILD_TYPE: ${{ env.TEST_ALL_PACKAGES == 'true' && '' || 'presubmit' }}
         TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
         TEST_TYPE: unit
         PY_VERSION: ${{ matrix.python }}
+        # Workaround: Allows libcst to compile on Python 3.15+ while PyO3 catches up
+        # Can be removed once libcst releases a version with native Python 3.15 wheels
+        # Follow https://github.com/Instagram/LibCST/issues/1445 for updates.
+        PYO3_USE_ABI3_FORWARD_COMPATIBILITY: "1"
+      run: |
+        UNIQUE_BATCH_PACKAGES=$(python -c 'import sys; sys.path.append("ci"); import get_batches; print(get_batches.get_batch_slice(${{ matrix.batch-index }}))')
+
+        if [ -z "$UNIQUE_BATCH_PACKAGES" ]; then
+          echo "No structural units allocated to this matrix slice."
+          exit 0
+        fi
+
+        echo "Running tests for packages in this weighted batch: ${UNIQUE_BATCH_PACKAGES}"
+        ci/run_conditional_tests.sh ${UNIQUE_BATCH_PACKAGES}
+
+    - name: Save Status Footprint
       run: |
-        ci/run_conditional_tests.sh
+        mkdir -p footprints
+        echo "${{ steps.run-tests.outcome }}" > footprints/status.txt
+
+    - name: Upload Status Footprint
+      uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
+      with:
+        name: footprint-${{ matrix.python }}-${{ matrix.batch-index }}
+        path: footprints/
+
     - name: Upload coverage results
       uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
       with:
-        name: coverage-artifact-${{ matrix.python }}
-        path: .coverage-${{ matrix.python }}
+        # Appended batch-index to separate parallel coverage uploads cleanly
+        name: coverage-artifact-${{ matrix.python }}-${{ matrix.batch-index }}
+        path: .coverage-${{ matrix.python }}-${{ matrix.batch-index }}
         include-hidden-files: true
 
   cover:
     runs-on: ubuntu-latest
-    needs:
-        - unit
+    needs: [unit]
     steps:
     - name: Checkout
       uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
@@ -182,3 +261,52 @@ jobs:
           echo "This usually means the unit tests did not run or failed to upload their coverage files."
           exit 1
         fi
+
+  unittest-runtime-result:
+    name: "unit (${{ matrix.python }})"
+    needs: [python_config, discover-packages, unit]
+    if: always()
+    strategy:
+      fail-fast: false
+      matrix:
+        python: ${{ fromJSON(needs.python_config.outputs.all_python) }}
+    runs-on: ubuntu-latest
+    steps:
+      - name: Download all status footprints for this runtime
+        uses: actions/download-artifact@634f93cb2916e3fdff6788551b99b062d0335ce0 # v5
+        with:
+          pattern: footprint-${{ matrix.python }}-*
+          path: footprint-results/
+
+      - name: Validate complete batch execution footprint status
+        run: |
+          EXPECTED_BATCHES=$(echo '${{ needs.discover-packages.outputs.batch-indices }}' | jq '. | length')
+          
+          if [ -d "footprint-results" ]; then
+            ACTUAL_BATCHES=$(find footprint-results -type f -name 'status.txt' | wc -l | tr -d ' ')
+          else
+            ACTUAL_BATCHES=0
+          fi
+
+          echo "Validation metrics for Python ${{ matrix.python }}:"
+          echo " -> Expected footprint files: $EXPECTED_BATCHES"
+          echo " -> Downloaded footprint files: $ACTUAL_BATCHES"
+
+          if [ "$ACTUAL_BATCHES" -ne "$EXPECTED_BATCHES" ]; then
+            echo "Error: Footprint count mismatch! Expected $EXPECTED_BATCHES files, but found $ACTUAL_BATCHES."
+            exit 1
+          fi
+
+          FAILED_RUNS=0
+          while read -r STATUS_FILE; do
+            RUN_STATUS=$(cat "$STATUS_FILE" | tr -d '[:space:]')
+            if [[ "$RUN_STATUS" != "success" ]]; then
+              echo "Failure detected in batch profile path: $STATUS_FILE (Status: $RUN_STATUS)"
+              FAILED_RUNS=$((FAILED_RUNS + 1))
+            fi
+          done < <(find footprint-results -type f -name 'status.txt' 2>/dev/null)
+
+          if [ "$FAILED_RUNS" -gt 0 ]; then
+            echo "Error: Validation failed. Found $FAILED_RUNS failing test batches."
+            exit 1
+          fi
diff --git a/.kokoro/presubmit/system.cfg b/.kokoro/presubmit/system.cfg
index 7b566963e011..0e3187b894b7 100644
--- a/.kokoro/presubmit/system.cfg
+++ b/.kokoro/presubmit/system.cfg
@@ -10,3 +10,5 @@ env_vars: {
   key: "BIGFRAMES_TEST_PROJECT"
   value: "bigframes-testing"
 }
+
+timeout_mins: 360
diff --git a/ci/get_batches.py b/ci/get_batches.py
new file mode 100644
index 000000000000..34f256020fd9
--- /dev/null
+++ b/ci/get_batches.py
@@ -0,0 +1,81 @@
+# Copyright 2026 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
+#
+#     http://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.
+#!/usr/bin/env python3
+import os
+import glob
+import math
+import json
+import sys
+
+BATCH_SIZE = 10
+
+# Packages that take significantly longer to run tests.
+# These will always be assigned to their own dedicated runner.
+ISOLATED_PACKAGES = [
+    "google-cloud-compute",
+    "google-cloud-compute-v1beta",
+    "google-cloud-dialogflow",
+    "google-cloud-dialogflow-cx",
+    "google-cloud-retail",
+]
+
+def get_batches():
+    """Splits packages into dedicated isolated batches and evenly chunked standard batches."""
+    raw_paths = sorted(glob.glob("packages/*"))
+    package_paths = [p for p in raw_paths if os.path.isdir(p)]
+    
+    batches = []
+    standard_packages = []
+    
+    for path in package_paths:
+        pkg_name = os.path.basename(path)
+        
+        if pkg_name in ISOLATED_PACKAGES:
+            # Put heavy packages into their own standalone batches immediately
+            batches.append([path])
+        else:
+            standard_packages.append(path)
+            
+    # Chunk the remaining standard packages by BATCH_SIZE
+    num_standard_packages = len(standard_packages)
+    num_standard_batches = math.ceil(num_standard_packages / BATCH_SIZE)
+    
+    if num_standard_batches == 0 and not batches:
+        num_standard_batches = 1
+        
+    for i in range(num_standard_batches):
+        start_idx = i * BATCH_SIZE
+        chunk = standard_packages[start_idx : start_idx + BATCH_SIZE]
+        if chunk:
+            batches.append(chunk)
+            
+    return batches
+
+def get_batch_indices():
+    """Returns a JSON string of the array of batch indices for GitHub Actions matrix."""
+    batches = get_batches()
+    return json.dumps(list(range(len(batches))))
+
+def get_batch_slice(batch_index):
+    """Returns a space-separated string of unique package paths for a specific batch index."""
+    batches = get_batches()
+    if batch_index < 0 or batch_index >= len(batches):
+        return ""
+    return " ".join(batches[batch_index])
+
+if __name__ == "__main__":
+    if len(sys.argv) > 1 and sys.argv[1] == "--count":
+        print(get_batch_indices())
+    elif len(sys.argv) > 2 and sys.argv[1] == "--slice":
+        print(get_batch_slice(int(sys.argv[2])))
diff --git a/ci/run_conditional_tests.sh b/ci/run_conditional_tests.sh
index b4df9cb923f4..674111df7ea1 100755
--- a/ci/run_conditional_tests.sh
+++ b/ci/run_conditional_tests.sh
@@ -21,6 +21,10 @@
 
 # `TEST_TYPE` and `PY_VERSION` are required by the script `ci/run_single_test.sh`
 
+# Optional Arguments:
+# Pass specific space-separated package paths (e.g., "packages/google-cloud-storage") to only test those directories.
+# If no arguments are provided, the script automatically determines which directories have changed
+#
 # This script will determine which directories have changed
 # under the `packages` folder. For `BUILD_TYPE=="presubmit"`,
 # we'll compare against the `packages` folder in HEAD,
@@ -78,17 +82,44 @@ set -e
 # Now we have a fixed list, but we can change it to autodetect if
 # necessary.
 
-subdirs=(
-    packages
-    preview-packages
-)
+if [ $# -gt 0 ]; then
+    subdirs=("$@")
+else
+    subdirs=(
+        packages
+        preview-packages
+    )
+fi
 
 RETVAL=0
 
-for subdir in ${subdirs[@]}; do
-    for d in `ls -d ${subdir}/*/`; do
+for subdir in "${subdirs[@]}"; do
+    if [ ! -d "${subdir}" ]; then
+        echo "Error: Directory '${subdir}' does not exist." >&2
+        exit 1
+    fi
+
+    if [[ "${subdir%/}" == "packages" ]]; then
+        loop_dirs=("${subdir}"/*/)
+    else
+        loop_dirs=("${subdir}")
+    fi
+
+    for d in "${loop_dirs[@]}"; do
+        if [ ! -d "$d" ]; then
+            continue
+        fi
+        # Ensure the directory path always ends with a trailing slash for git diff safety
+        if [[ "$d" != */ ]]; then
+            d="$d/"
+        fi
         should_test=false
-        if [ -n "${GIT_DIFF_ARG}" ]; then
+        
+        # Override check: Force test if explicitly asked to test all packages
+        if [[ "${TEST_ALL_PACKAGES}" == "true" ]]; then
+            echo "TEST_ALL_PACKAGES is true, forcing execution for ${d}"
+            should_test=true
+        elif [ -n "${GIT_DIFF_ARG}" ]; then
             echo "checking changes with 'git diff --quiet ${GIT_DIFF_ARG} ${d}'"
             set +e
             git diff --quiet ${GIT_DIFF_ARG} ${d}
@@ -120,4 +151,4 @@ for subdir in ${subdirs[@]}; do
     done
 done
 
-exit ${RETVAL}
+exit ${RETVAL}
\ No newline at end of file
diff --git a/ci/run_single_test.sh b/ci/run_single_test.sh
index 8f4a034d5097..646bb8db99f8 100755
--- a/ci/run_single_test.sh
+++ b/ci/run_single_test.sh
@@ -90,6 +90,11 @@ case ${TEST_TYPE} in
             nox -s unit-3.14
             retval=$?
             ;;
+        "3.15")
+            # This is needed to speed up builds
+            nox --force-venv-backend uv -s unit-3.15
+            retval=$?
+            ;;
         *)
             echo "unsupported PY_VERSION"
             exit 1
diff --git a/packages/bigframes/mypy.ini b/packages/bigframes/mypy.ini
deleted file mode 100644
index e3f44c262ac6..000000000000
--- a/packages/bigframes/mypy.ini
+++ /dev/null
@@ -1,49 +0,0 @@
-# https://mypy.readthedocs.io/en/stable/config_file.html#config-file
-
-[mypy]
-exclude = ^third_party/
-
-[mypy-google.auth.*]
-ignore_missing_imports = True
-
-[mypy-cloudpickle.*]
-ignore_missing_imports = True
-
-[mypy-flask]
-ignore_missing_imports = True
-
-[mypy-pydata_google_auth]
-ignore_missing_imports = True
-
-[mypy-google.colab]
-ignore_missing_imports = True
-
-[mypy-google.iam.*]
-ignore_missing_imports = True
-
-[mypy-pytz]
-ignore_missing_imports = True
-
-[mypy-pyarrow]
-ignore_missing_imports = True
-
-[mypy-ibis.*]
-ignore_missing_imports = True
-
-[mypy-ipywidgets]
-ignore_missing_imports = True
-
-[mypy-pyarrow.feather]
-ignore_missing_imports = True
-
-[mypy-google.cloud.pubsub]
-ignore_missing_imports = True
-
-[mypy-google.cloud.bigtable]
-ignore_missing_imports = True
-
-[mypy-anywidget]
-ignore_missing_imports = True
-
-[mypy-bigframes_vendored.*]
-ignore_errors = True
diff --git a/packages/bigframes/noxfile.py b/packages/bigframes/noxfile.py
index 8cbbddfc61aa..839e6e0e1158 100644
--- a/packages/bigframes/noxfile.py
+++ b/packages/bigframes/noxfile.py
@@ -60,7 +60,7 @@
 
 DEFAULT_PYTHON_VERSION = "3.14"
 
-ALL_PYTHON = ["3.10", "3.11", "3.12", "3.13", "3.14"]
+ALL_PYTHON = ["3.10", "3.11", "3.12", "3.13", "3.14", "3.15"]
 UNIT_TEST_STANDARD_DEPENDENCIES = [
     "mock",
     PYTEST_VERSION,
@@ -283,6 +283,10 @@ def run_unit(session, install_test_extra):
 @nox.session(python=ALL_PYTHON)
 @nox.parametrize("test_extra", [True, False])
 def unit(session, test_extra):
+    if session.python == "3.15":
+        session.skip(
+            "Skipping 3.15 until wheels are available for pyarrow. Also pyproj wheels are needed for dependency geopandas."
+        )
     if test_extra:
         run_unit(session, install_test_extra=test_extra)
     else:
diff --git a/packages/bigquery-magics/noxfile.py b/packages/bigquery-magics/noxfile.py
index 0a2a15597580..7a273ac28419 100644
--- a/packages/bigquery-magics/noxfile.py
+++ b/packages/bigquery-magics/noxfile.py
@@ -41,6 +41,7 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 
 UNIT_TEST_STANDARD_DEPENDENCIES = [
@@ -237,6 +238,10 @@ def install_unittest_dependencies(session, *constraints):
 @nox.session(python=UNIT_TEST_PYTHON_VERSIONS)
 def unit(session):
     # Install all test dependencies, then install this package in-place.
+    if session.python == "3.15":
+        session.skip(
+            "Skipping 3.15 until wheels are available for pyproj needed for dependency geopandas"
+        )
 
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
diff --git a/packages/bigquery-magics/testing/constraints-3.15.txt b/packages/bigquery-magics/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/db-dtypes/noxfile.py b/packages/db-dtypes/noxfile.py
index afd1ab00a637..b26f72f7a285 100644
--- a/packages/db-dtypes/noxfile.py
+++ b/packages/db-dtypes/noxfile.py
@@ -42,6 +42,7 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 
 UNIT_TEST_STANDARD_DEPENDENCIES = [
@@ -302,6 +303,8 @@ def prerelease(session, tests_path):
 @nox.parametrize("test_type", ["unit", "compliance"])
 def unit(session, test_type):
     """Run the unit test suite."""
+    if session.python == "3.15":
+        session.skip("Skipping 3.15 until wheels are available for pyarrow.")
 
     # Compliance tests only run on the latest Python version
     if test_type == "compliance" and session.python != DEFAULT_PYTHON_VERSION:
diff --git a/packages/db-dtypes/testing/constraints-3.15.txt b/packages/db-dtypes/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/django-google-spanner/noxfile.py b/packages/django-google-spanner/noxfile.py
index b867418df7bf..612fafe793f9 100644
--- a/packages/django-google-spanner/noxfile.py
+++ b/packages/django-google-spanner/noxfile.py
@@ -34,6 +34,7 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 ALL_PYTHON = list(UNIT_TEST_PYTHON_VERSIONS)
 
diff --git a/packages/django-google-spanner/testing/constraints-3.15.txt b/packages/django-google-spanner/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/gcp-sphinx-docfx-yaml/noxfile.py b/packages/gcp-sphinx-docfx-yaml/noxfile.py
index 4fb1a1e9baa1..eba996702d4d 100644
--- a/packages/gcp-sphinx-docfx-yaml/noxfile.py
+++ b/packages/gcp-sphinx-docfx-yaml/noxfile.py
@@ -18,7 +18,7 @@
 import nox
 
 DEFAULT_PYTHON_VERSION = "3.14"
-UNIT_TEST_PYTHON_VERSIONS = ["3.10", "3.11", "3.12", "3.13", "3.14"]
+UNIT_TEST_PYTHON_VERSIONS = ["3.10", "3.11", "3.12", "3.13", "3.14", "3.15"]
 CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
 # Path to the centralized mypy configuration file at the repository root.
 # Search upwards to support running nox from both monorepo packages and integration test goldens.
@@ -166,7 +166,7 @@ def unit(session):
     # Re-enable 3.11, 3.12, and 3.13 after environment verification.
     # TODO(https://github.com/googleapis/google-cloud-python/issues/16176):
     # Track 3.14 compatibility as upstream dependencies stabilize.
-    _skip_python_session(session, ["3.11", "3.12", "3.13", "3.14"])
+    _skip_python_session(session, ["3.11", "3.12", "3.13", "3.14", "3.15"])
     session.install("-r", "requirements.txt")
     session.install("pytest", "pytest-cov")
     session.run(
diff --git a/packages/google-api-core/noxfile.py b/packages/google-api-core/noxfile.py
index fca53607bdb2..673b91043bd6 100644
--- a/packages/google-api-core/noxfile.py
+++ b/packages/google-api-core/noxfile.py
@@ -31,8 +31,7 @@
 RUFF_VERSION = "ruff==0.14.14"
 LINT_PATHS = ["docs", "google", "tests", "noxfile.py", "setup.py"]
 
-ALL_PYTHON = ["3.10", "3.11", "3.12", "3.13", "3.14"]
-SUPPORTED_PYTHON_VERSIONS = ["3.10", "3.11", "3.12", "3.13", "3.14"]
+ALL_PYTHON = ["3.10", "3.11", "3.12", "3.13", "3.14", "3.15"]
 
 DEFAULT_PYTHON_VERSION = "3.14"
 CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
@@ -231,14 +230,14 @@ def default(
     if prerelease:
         install_prerelease_dependencies(
             session,
-            f"{constraints_dir}/constraints-{constraints_type}{SUPPORTED_PYTHON_VERSIONS[0]}.txt",
+            f"{constraints_dir}/constraints-{constraints_type}{ALL_PYTHON[0]}.txt",
         )
         # This *must* be the last install command to get the package from source.
         session.install("-e", lib_with_extras, "--no-deps")
     elif install_deps_from_source:
         install_core_deps_dependencies(
             session,
-            f"{constraints_dir}/constraints-{constraints_type}{SUPPORTED_PYTHON_VERSIONS[0]}.txt",
+            f"{constraints_dir}/constraints-{constraints_type}{ALL_PYTHON[0]}.txt",
         )
         # This *must* be the last install command to get the package from source.
         session.install("-e", lib_with_extras, "--no-deps")
diff --git a/packages/google-api-core/testing/constraints-3.15.txt b/packages/google-api-core/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/google-auth-httplib2/noxfile.py b/packages/google-auth-httplib2/noxfile.py
index 162301d4f13b..df530819a42d 100644
--- a/packages/google-auth-httplib2/noxfile.py
+++ b/packages/google-auth-httplib2/noxfile.py
@@ -39,6 +39,7 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 UNIT_TEST_STANDARD_DEPENDENCIES = [
     "mock",
diff --git a/packages/google-auth-httplib2/testing/constraints-3.15.txt b/packages/google-auth-httplib2/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/google-auth-oauthlib/noxfile.py b/packages/google-auth-oauthlib/noxfile.py
index 1a7f043e7461..eb5419d94ec2 100644
--- a/packages/google-auth-oauthlib/noxfile.py
+++ b/packages/google-auth-oauthlib/noxfile.py
@@ -41,6 +41,7 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 UNIT_TEST_STANDARD_DEPENDENCIES = [
     "mock",
diff --git a/packages/google-auth-oauthlib/testing/constraints-3.15.txt b/packages/google-auth-oauthlib/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/google-auth/noxfile.py b/packages/google-auth/noxfile.py
index 38e5f4d82f70..86a31f3b4660 100644
--- a/packages/google-auth/noxfile.py
+++ b/packages/google-auth/noxfile.py
@@ -46,10 +46,7 @@
 
 DEFAULT_PYTHON_VERSION = "3.14"
 
-# TODO(https://github.com/googleapis/gapic-generator-python/issues/2450):
-# Switch this to Python 3.15 alpha1
-# https://peps.python.org/pep-0790/
-PREVIEW_PYTHON_VERSION = "3.14"
+PREVIEW_PYTHON_VERSION = "3.15"
 
 UNIT_TEST_PYTHON_VERSIONS = [
     "3.10",
@@ -57,6 +54,7 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 ALL_PYTHON = UNIT_TEST_PYTHON_VERSIONS.copy()
 
diff --git a/packages/google-auth/testing/constraints-3.15.txt b/packages/google-auth/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/google-cloud-access-context-manager/noxfile.py b/packages/google-cloud-access-context-manager/noxfile.py
index ab17625e3f2e..dfe8d9a71759 100644
--- a/packages/google-cloud-access-context-manager/noxfile.py
+++ b/packages/google-cloud-access-context-manager/noxfile.py
@@ -37,9 +37,10 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 
-DEFAULT_PYTHON_VERSION = UNIT_TEST_PYTHON_VERSIONS[-1]
+DEFAULT_PYTHON_VERSION = "3.14"
 
 UNIT_TEST_STANDARD_DEPENDENCIES = [
     "mock",
diff --git a/packages/google-cloud-access-context-manager/testing/constraints-3.15.txt b/packages/google-cloud-access-context-manager/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/google-cloud-audit-log/noxfile.py b/packages/google-cloud-audit-log/noxfile.py
index f35f358125a4..55c291dcf63e 100644
--- a/packages/google-cloud-audit-log/noxfile.py
+++ b/packages/google-cloud-audit-log/noxfile.py
@@ -37,9 +37,10 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 
-DEFAULT_PYTHON_VERSION = UNIT_TEST_PYTHON_VERSIONS[-1]
+DEFAULT_PYTHON_VERSION = "3.14"
 
 UNIT_TEST_STANDARD_DEPENDENCIES = [
     "mock",
diff --git a/packages/google-cloud-audit-log/testing/constraints-3.15.txt b/packages/google-cloud-audit-log/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/google-cloud-bigquery/.coveragerc b/packages/google-cloud-bigquery/.coveragerc
index e78e7a931e09..a22bacb57e19 100644
--- a/packages/google-cloud-bigquery/.coveragerc
+++ b/packages/google-cloud-bigquery/.coveragerc
@@ -2,7 +2,7 @@
 branch = True
 
 [report]
-fail_under = 100
+fail_under = 99
 show_missing = True
 omit =
     google/cloud/bigquery/__init__.py
diff --git a/packages/google-cloud-bigquery/noxfile.py b/packages/google-cloud-bigquery/noxfile.py
index d4accfea91a4..f4e899fc553c 100644
--- a/packages/google-cloud-bigquery/noxfile.py
+++ b/packages/google-cloud-bigquery/noxfile.py
@@ -38,7 +38,7 @@
 )
 
 DEFAULT_PYTHON_VERSION = "3.14"
-ALL_PYTHON = ["3.10", "3.11", "3.12", "3.13", "3.14"]
+ALL_PYTHON = ["3.10", "3.11", "3.12", "3.13", "3.14", "3.15"]
 UNIT_TEST_PYTHON_VERSIONS = ALL_PYTHON
 CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
 # Path to the centralized mypy configuration file at the repository root.
@@ -180,6 +180,10 @@ def default(session, install_extras=True):
 @_calculate_duration
 def unit(session, test_type):
     """Run the unit test suite."""
+    if session.python == "3.15":
+        session.skip(
+            "Skipping 3.15 until wheels are available for pyarrow. Also pyproj wheels are needed for dependency geopandas."
+        )
 
     install_extras = True
     if test_type == "unit_noextras":
diff --git a/packages/google-cloud-bigquery/testing/constraints-3.15.txt b/packages/google-cloud-bigquery/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/google-cloud-bigtable/noxfile.py b/packages/google-cloud-bigtable/noxfile.py
index f8d639a266ed..0ffdf5d3c1ff 100644
--- a/packages/google-cloud-bigtable/noxfile.py
+++ b/packages/google-cloud-bigtable/noxfile.py
@@ -242,6 +242,9 @@ def unit(session, protobuf_implementation):
     if session.python == "3.15":
         session.skip("Skipping 3.15 until wheels are available for google-crc32c.")
 
+    if session.python == "3.15":
+        session.skip("Skipping 3.15 until wheels are available for google-crc32c.")
+
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
diff --git a/packages/google-cloud-core/noxfile.py b/packages/google-cloud-core/noxfile.py
index a86e71252c69..772c0c136b3d 100644
--- a/packages/google-cloud-core/noxfile.py
+++ b/packages/google-cloud-core/noxfile.py
@@ -32,6 +32,7 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
 # Path to the centralized mypy configuration file at the repository root.
diff --git a/packages/google-cloud-core/testing/constraints-3.15.txt b/packages/google-cloud-core/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/google-cloud-dns/noxfile.py b/packages/google-cloud-dns/noxfile.py
index 55c042e6b68f..c7e04c73bc5a 100644
--- a/packages/google-cloud-dns/noxfile.py
+++ b/packages/google-cloud-dns/noxfile.py
@@ -41,6 +41,7 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 UNIT_TEST_STANDARD_DEPENDENCIES = [
     "mock",
diff --git a/packages/google-cloud-dns/testing/constraints-3.15.txt b/packages/google-cloud-dns/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/google-cloud-documentai-toolbox/noxfile.py b/packages/google-cloud-documentai-toolbox/noxfile.py
index d046a6f3d39b..18a537cb9bda 100644
--- a/packages/google-cloud-documentai-toolbox/noxfile.py
+++ b/packages/google-cloud-documentai-toolbox/noxfile.py
@@ -41,6 +41,7 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 
 UNIT_TEST_STANDARD_DEPENDENCIES = [
@@ -199,6 +200,10 @@ def install_unittest_dependencies(session, *constraints):
 )
 def unit(session, protobuf_implementation):
     # Install all test dependencies, then install this package in-place.
+    if session.python == "3.15":
+        session.skip(
+            "Skipping 3.15 until wheels are available for 1. numba (from dependency pandas[performance]) 2. lxml (from dependency pikepdf) 3. pyarrow."
+        )
 
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
diff --git a/packages/google-cloud-documentai-toolbox/setup.py b/packages/google-cloud-documentai-toolbox/setup.py
index 0d71958686e5..8765caa5b94a 100644
--- a/packages/google-cloud-documentai-toolbox/setup.py
+++ b/packages/google-cloud-documentai-toolbox/setup.py
@@ -54,7 +54,10 @@
     },
     install_requires=(
         "google-api-core>=2.25.0, <3.0.0",
-        "pandas[performance,gcp]>=2.0.0, <3.0.0",
+        # For Python < 3.15: Install with performance extras (which includes numba)
+        "pandas[performance,gcp]>=2.0.0, <3.0.0; python_version < '3.15'",
+        # pandas[performance] requires numba which does not have 3.15 support yet
+        "pandas[gcp]>=2.0.0, <3.0.0;python_version>='3.15'",
         "pyarrow>=15.0.0, <23.0.0",
         "tabulate>=0.9.0, <1.0.0",
         "proto-plus>=1.26.1, <2.0.0",
diff --git a/packages/google-cloud-documentai-toolbox/testing/constraints-3.15.txt b/packages/google-cloud-documentai-toolbox/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..af6f7f358d70
--- /dev/null
+++ b/packages/google-cloud-documentai-toolbox/testing/constraints-3.15.txt
@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+# This constraints file is required for unit tests.
+# List all library dependencies and extras in this file.
+google-api-core
+pandas
+proto-plus
+grpc-google-iam-v1
+google-cloud-bigquery
+google-cloud-documentai
+google-cloud-storage
+numpy
+pikepdf
+numba>=0.63.0b1
diff --git a/packages/google-cloud-ndb/noxfile.py b/packages/google-cloud-ndb/noxfile.py
index 93564ffa28e0..cb957a674ed1 100644
--- a/packages/google-cloud-ndb/noxfile.py
+++ b/packages/google-cloud-ndb/noxfile.py
@@ -29,7 +29,7 @@
 LOCAL_DEPS = ("google-api-core", "google-cloud-core")
 NOX_DIR = os.path.abspath(os.path.dirname(__file__))
 DEFAULT_INTERPRETER = "3.14"
-ALL_INTERPRETERS = ("3.10", "3.11", "3.12", "3.13", "3.14")
+ALL_INTERPRETERS = ("3.10", "3.11", "3.12", "3.13", "3.14", "3.15")
 CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
 # Path to the centralized mypy configuration file at the repository root.
 # Search upwards to support running nox from both monorepo packages and integration test goldens.
diff --git a/packages/google-cloud-ndb/testing/constraints-3.15.txt b/packages/google-cloud-ndb/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..0d0adf684566
--- /dev/null
+++ b/packages/google-cloud-ndb/testing/constraints-3.15.txt
@@ -0,0 +1,8 @@
+# We use the constraints file for the latest Python version
+# (currently this file) to check that the latest
+# major versions of dependencies are supported in setup.py.
+# List all library dependencies and extras in this file.
+# Require the latest major version be installed for each dependency.
+# e.g., if setup.py has "google-cloud-foo >= 1.14.0, < 2.0.0",
+# Then this file should have google-cloud-foo>=1
+redis>=7
diff --git a/packages/google-cloud-runtimeconfig/noxfile.py b/packages/google-cloud-runtimeconfig/noxfile.py
index f4e52787ebf7..75f3c0a98e3f 100644
--- a/packages/google-cloud-runtimeconfig/noxfile.py
+++ b/packages/google-cloud-runtimeconfig/noxfile.py
@@ -41,6 +41,7 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 UNIT_TEST_STANDARD_DEPENDENCIES = [
     "mock",
diff --git a/packages/google-cloud-runtimeconfig/testing/constraints-3.15.txt b/packages/google-cloud-runtimeconfig/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/google-cloud-spanner-dbapi-driver/noxfile.py b/packages/google-cloud-spanner-dbapi-driver/noxfile.py
index 39b30c73916b..b03d6ac78d4d 100644
--- a/packages/google-cloud-spanner-dbapi-driver/noxfile.py
+++ b/packages/google-cloud-spanner-dbapi-driver/noxfile.py
@@ -38,15 +38,13 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 
 DEFAULT_PYTHON_VERSION = "3.14"
 DOCS_PYTHON_VERSION = "3.10"
 
-# TODO(https://github.com/googleapis/gapic-generator-python/issues/2450):
-# Switch this to Python 3.15 alpha1
-# https://peps.python.org/pep-0790/
-PREVIEW_PYTHON_VERSION = "3.14"
+PREVIEW_PYTHON_VERSION = "3.15"
 
 CURRENT_DIRECTORY = pathlib.Path(__file__).parent.absolute()
 # Path to the centralized mypy configuration file at the repository root.
diff --git a/packages/google-cloud-spanner-dbapi-driver/testing/constraints-3.15.txt b/packages/google-cloud-spanner-dbapi-driver/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..2d4c01d5696a
--- /dev/null
+++ b/packages/google-cloud-spanner-dbapi-driver/testing/constraints-3.15.txt
@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+# This constraints file is required for unit tests.
+# List all library dependencies and extras in this file.
+spannerlib-python
diff --git a/packages/google-cloud-storage/noxfile.py b/packages/google-cloud-storage/noxfile.py
index 8e206c4cca76..7f8f561031fd 100644
--- a/packages/google-cloud-storage/noxfile.py
+++ b/packages/google-cloud-storage/noxfile.py
@@ -279,6 +279,10 @@ def install_unittest_dependencies(session, *constraints):
 def unit(session, protobuf_implementation):
     # Install all test dependencies, then install this package in-place.
 
+    if session.python == "3.15":
+        session.skip(
+            "Skipping 3.15 until compatible wheels are available for google-crc32c"
+        )
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
diff --git a/packages/google-cloud-testutils/noxfile.py b/packages/google-cloud-testutils/noxfile.py
index caebbf8ef459..c7bde14d4e51 100644
--- a/packages/google-cloud-testutils/noxfile.py
+++ b/packages/google-cloud-testutils/noxfile.py
@@ -33,7 +33,7 @@
 # Error if a python version is missing
 nox.options.error_on_missing_interpreters = True
 
-ALL_PYTHON = ["3.10", "3.11", "3.12", "3.13", "3.14"]
+ALL_PYTHON = ["3.10", "3.11", "3.12", "3.13", "3.14", "3.15"]
 DEFAULT_PYTHON_VERSION = "3.14"
 BLACK_VERSION = "black==23.7.0"
 RUFF_VERSION = "ruff==0.14.14"
diff --git a/packages/google-cloud-testutils/testing/constraints-3.15.txt b/packages/google-cloud-testutils/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/google-resumable-media/noxfile.py b/packages/google-resumable-media/noxfile.py
index 6d0f35f30375..3dc0eb922231 100644
--- a/packages/google-resumable-media/noxfile.py
+++ b/packages/google-resumable-media/noxfile.py
@@ -37,7 +37,7 @@
 RUFF_VERSION = "ruff==0.14.14"
 
 DEFAULT_PYTHON_VERSION = "3.14"
-UNIT_TEST_PYTHON_VERSIONS = ["3.10", "3.11", "3.12", "3.13", "3.14"]
+UNIT_TEST_PYTHON_VERSIONS = ["3.10", "3.11", "3.12", "3.13", "3.14", "3.15"]
 SYSTEM_TEST_PYTHON_VERSIONS = UNIT_TEST_PYTHON_VERSIONS
 
 # Error if a python version is missing
diff --git a/packages/google-resumable-media/testing/constraints-3.15.txt b/packages/google-resumable-media/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/googleapis-common-protos/noxfile.py b/packages/googleapis-common-protos/noxfile.py
index e43d6651c824..78fd0cbf4ff9 100644
--- a/packages/googleapis-common-protos/noxfile.py
+++ b/packages/googleapis-common-protos/noxfile.py
@@ -37,9 +37,10 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 
-DEFAULT_PYTHON_VERSION = UNIT_TEST_PYTHON_VERSIONS[-1]
+DEFAULT_PYTHON_VERSION = "3.14"
 
 UNIT_TEST_STANDARD_DEPENDENCIES = [
     "mock",
diff --git a/packages/googleapis-common-protos/testing/constraints-3.15.txt b/packages/googleapis-common-protos/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/grpc-google-iam-v1/noxfile.py b/packages/grpc-google-iam-v1/noxfile.py
index 291eb1341764..7b66e0144f73 100644
--- a/packages/grpc-google-iam-v1/noxfile.py
+++ b/packages/grpc-google-iam-v1/noxfile.py
@@ -37,9 +37,10 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 
-DEFAULT_PYTHON_VERSION = UNIT_TEST_PYTHON_VERSIONS[-1]
+DEFAULT_PYTHON_VERSION = "3.14"
 
 UNIT_TEST_STANDARD_DEPENDENCIES = [
     "mock",
diff --git a/packages/grpc-google-iam-v1/testing/constraints-3.15.txt b/packages/grpc-google-iam-v1/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/pandas-gbq/noxfile.py b/packages/pandas-gbq/noxfile.py
index aabc6426becb..0021226416cd 100644
--- a/packages/pandas-gbq/noxfile.py
+++ b/packages/pandas-gbq/noxfile.py
@@ -41,6 +41,7 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 
 UNIT_TEST_STANDARD_DEPENDENCIES = [
@@ -253,6 +254,11 @@ def default(session):
 @_calculate_duration
 def unit(session):
     """Run the unit test suite."""
+    if session.python == "3.15":
+        session.skip(
+            "Skipping 3.15 until wheels are available for pyarrow. Also pyproj wheels are needed for dependency geopandas."
+        )
+
     default(session)
 
 
diff --git a/packages/pandas-gbq/testing/constraints-3.15.txt b/packages/pandas-gbq/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1
diff --git a/packages/proto-plus/noxfile.py b/packages/proto-plus/noxfile.py
index 57a12b5eaa13..5f56955863c8 100644
--- a/packages/proto-plus/noxfile.py
+++ b/packages/proto-plus/noxfile.py
@@ -47,6 +47,7 @@
     "3.12",
     "3.13",
     "3.14",
+    "3.15",
 ]
 
 # Error if a python version is missing
diff --git a/packages/proto-plus/testing/constraints-3.15.txt b/packages/proto-plus/testing/constraints-3.15.txt
new file mode 100644
index 000000000000..e69de29bb2d1

From c5e39800a7d19ecf64abc57714e6328609f08fb5 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 17:33:10 +0000
Subject: [PATCH 02/22] git checkout origin/main 
 .github/workflows/unittest.yml

---
 .github/workflows/unittest.yml | 150 +++------------------------------
 1 file changed, 11 insertions(+), 139 deletions(-)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 951bf84200c4..392f5ece6270 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -12,50 +12,13 @@ name: unittest
 permissions:
   contents: read
 
-# Configurable global environment variables for batching
-env:
-  TEST_ALL_PACKAGES: "false" # Set to "false" to only run tests for packages with a git diff
-  ALL_PYTHON: "['3.10', '3.11', '3.12', '3.13', '3.14', '3.15']"
-  # Force static compilation of libxml2 and libxslt for lxml packages
-  STATIC_DEPS: "true"
-
 jobs:
-  # Dynamic package discovery job to calculate required matrix size automatically
-  python_config:
-    runs-on: ubuntu-latest
-    outputs:
-      all_python: ${{ steps.export.outputs.python_list }}
-    steps:
-      - id: export
-        run: echo "python_list=${{ env.ALL_PYTHON }}" >> "$GITHUB_OUTPUT"
-
-  discover-packages:
-    runs-on: ubuntu-latest
-    outputs:
-      batch-indices: ${{ steps.set-matrix.outputs.indices }}
-    steps:
-    - name: Checkout
-      uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
-      with:
-        persist-credentials: false
-    - name: Setup Python
-      uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6
-      with:
-        python-version: "3.14"
-    - name: Generate Batch Indices
-      id: set-matrix
-      run: |
-        INDICES=$(python -c 'import sys; sys.path.append("ci"); import get_batches; print(get_batches.get_batch_indices())')
-        echo "indices=${INDICES}" >> "$GITHUB_OUTPUT"
-
   unit:
-    name: "unit-run (${{ matrix.python }}, Batch ${{ matrix.batch-index }})"
     runs-on: ubuntu-22.04
-    needs: [python_config, discover-packages]
     strategy:
+      fail-fast: true
       matrix:
-        python: ${{ fromJSON(needs.python_config.outputs.all_python) }}
-        batch-index: ${{ fromJson(needs.discover-packages.outputs.batch-indices) }}
+        python: ['3.10', "3.11", "3.12", "3.13", "3.14"]
     steps:
     - name: Checkout
       uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
@@ -69,72 +32,30 @@ jobs:
       uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6
       with:
         python-version: ${{ matrix.python }}
-        allow-prereleases: true
-    - name: Setup uv
-      uses: astral-sh/setup-uv@v5
-      with:
-        enable-cache: true
-        cache-dependency-glob: 'packages/**/testing/constraints*.txt'
     - name: Install nox
       run: |
-        uv pip install --system nox nox-uv
-    # Caches compiled wheels locally to prevent building heavy libraries
-    # such as grpcio, which we build from scratch on every run for Python 3.15+.
-    # Follow https://github.com/grpc/grpc/issues/41010 for updates.
-    - name: Cache Built Python 3.15 Wheels
-      if: matrix.python == '3.15'
-      uses: actions/cache@v4
-      with:
-        path: .uv-wheel-cache
-        key: ${{ runner.os }}-uv-wheels-3.15-${{ hashFiles('packages/**/testing/constraints*.txt') }}
-        restore-keys: |
-          ${{ runner.os }}-uv-wheels-3.15-
+        python -m pip install --upgrade setuptools pip wheel
+        python -m pip install nox
     - name: Run unit tests
-      id: run-tests
       env:
-        COVERAGE_FILE: ${{ github.workspace }}/.coverage-${{ matrix.python }}-${{ matrix.batch-index }}
-        # Dynamically set BUILD_TYPE to an empty string to skip the diff calculation if TEST_ALL_PACKAGES is true
-        BUILD_TYPE: ${{ env.TEST_ALL_PACKAGES == 'true' && '' || 'presubmit' }}
+        COVERAGE_FILE: ${{ github.workspace }}/.coverage-${{ matrix.python }}
+        BUILD_TYPE: presubmit
         TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
         TEST_TYPE: unit
         PY_VERSION: ${{ matrix.python }}
-        # Workaround: Allows libcst to compile on Python 3.15+ while PyO3 catches up
-        # Can be removed once libcst releases a version with native Python 3.15 wheels
-        # Follow https://github.com/Instagram/LibCST/issues/1445 for updates.
-        PYO3_USE_ABI3_FORWARD_COMPATIBILITY: "1"
-      run: |
-        UNIQUE_BATCH_PACKAGES=$(python -c 'import sys; sys.path.append("ci"); import get_batches; print(get_batches.get_batch_slice(${{ matrix.batch-index }}))')
-
-        if [ -z "$UNIQUE_BATCH_PACKAGES" ]; then
-          echo "No structural units allocated to this matrix slice."
-          exit 0
-        fi
-
-        echo "Running tests for packages in this weighted batch: ${UNIQUE_BATCH_PACKAGES}"
-        ci/run_conditional_tests.sh ${UNIQUE_BATCH_PACKAGES}
-
-    - name: Save Status Footprint
       run: |
-        mkdir -p footprints
-        echo "${{ steps.run-tests.outcome }}" > footprints/status.txt
-
-    - name: Upload Status Footprint
-      uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
-      with:
-        name: footprint-${{ matrix.python }}-${{ matrix.batch-index }}
-        path: footprints/
-
+        ci/run_conditional_tests.sh
     - name: Upload coverage results
       uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
       with:
-        # Appended batch-index to separate parallel coverage uploads cleanly
-        name: coverage-artifact-${{ matrix.python }}-${{ matrix.batch-index }}
-        path: .coverage-${{ matrix.python }}-${{ matrix.batch-index }}
+        name: coverage-artifact-${{ matrix.python }}
+        path: .coverage-${{ matrix.python }}
         include-hidden-files: true
 
   cover:
     runs-on: ubuntu-latest
-    needs: [unit]
+    needs:
+        - unit
     steps:
     - name: Checkout
       uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
@@ -261,52 +182,3 @@ jobs:
           echo "This usually means the unit tests did not run or failed to upload their coverage files."
           exit 1
         fi
-
-  unittest-runtime-result:
-    name: "unit (${{ matrix.python }})"
-    needs: [python_config, discover-packages, unit]
-    if: always()
-    strategy:
-      fail-fast: false
-      matrix:
-        python: ${{ fromJSON(needs.python_config.outputs.all_python) }}
-    runs-on: ubuntu-latest
-    steps:
-      - name: Download all status footprints for this runtime
-        uses: actions/download-artifact@634f93cb2916e3fdff6788551b99b062d0335ce0 # v5
-        with:
-          pattern: footprint-${{ matrix.python }}-*
-          path: footprint-results/
-
-      - name: Validate complete batch execution footprint status
-        run: |
-          EXPECTED_BATCHES=$(echo '${{ needs.discover-packages.outputs.batch-indices }}' | jq '. | length')
-          
-          if [ -d "footprint-results" ]; then
-            ACTUAL_BATCHES=$(find footprint-results -type f -name 'status.txt' | wc -l | tr -d ' ')
-          else
-            ACTUAL_BATCHES=0
-          fi
-
-          echo "Validation metrics for Python ${{ matrix.python }}:"
-          echo " -> Expected footprint files: $EXPECTED_BATCHES"
-          echo " -> Downloaded footprint files: $ACTUAL_BATCHES"
-
-          if [ "$ACTUAL_BATCHES" -ne "$EXPECTED_BATCHES" ]; then
-            echo "Error: Footprint count mismatch! Expected $EXPECTED_BATCHES files, but found $ACTUAL_BATCHES."
-            exit 1
-          fi
-
-          FAILED_RUNS=0
-          while read -r STATUS_FILE; do
-            RUN_STATUS=$(cat "$STATUS_FILE" | tr -d '[:space:]')
-            if [[ "$RUN_STATUS" != "success" ]]; then
-              echo "Failure detected in batch profile path: $STATUS_FILE (Status: $RUN_STATUS)"
-              FAILED_RUNS=$((FAILED_RUNS + 1))
-            fi
-          done < <(find footprint-results -type f -name 'status.txt' 2>/dev/null)
-
-          if [ "$FAILED_RUNS" -gt 0 ]; then
-            echo "Error: Validation failed. Found $FAILED_RUNS failing test batches."
-            exit 1
-          fi

From 46fdb3dd4715242e821cd0e4d192ac0a48146110 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 17:34:05 +0000
Subject: [PATCH 03/22] git checkout origin/main  ci/run_conditional_tests.sh

---
 ci/run_conditional_tests.sh | 47 +++++++------------------------------
 1 file changed, 8 insertions(+), 39 deletions(-)

diff --git a/ci/run_conditional_tests.sh b/ci/run_conditional_tests.sh
index 674111df7ea1..b4df9cb923f4 100755
--- a/ci/run_conditional_tests.sh
+++ b/ci/run_conditional_tests.sh
@@ -21,10 +21,6 @@
 
 # `TEST_TYPE` and `PY_VERSION` are required by the script `ci/run_single_test.sh`
 
-# Optional Arguments:
-# Pass specific space-separated package paths (e.g., "packages/google-cloud-storage") to only test those directories.
-# If no arguments are provided, the script automatically determines which directories have changed
-#
 # This script will determine which directories have changed
 # under the `packages` folder. For `BUILD_TYPE=="presubmit"`,
 # we'll compare against the `packages` folder in HEAD,
@@ -82,44 +78,17 @@ set -e
 # Now we have a fixed list, but we can change it to autodetect if
 # necessary.
 
-if [ $# -gt 0 ]; then
-    subdirs=("$@")
-else
-    subdirs=(
-        packages
-        preview-packages
-    )
-fi
+subdirs=(
+    packages
+    preview-packages
+)
 
 RETVAL=0
 
-for subdir in "${subdirs[@]}"; do
-    if [ ! -d "${subdir}" ]; then
-        echo "Error: Directory '${subdir}' does not exist." >&2
-        exit 1
-    fi
-
-    if [[ "${subdir%/}" == "packages" ]]; then
-        loop_dirs=("${subdir}"/*/)
-    else
-        loop_dirs=("${subdir}")
-    fi
-
-    for d in "${loop_dirs[@]}"; do
-        if [ ! -d "$d" ]; then
-            continue
-        fi
-        # Ensure the directory path always ends with a trailing slash for git diff safety
-        if [[ "$d" != */ ]]; then
-            d="$d/"
-        fi
+for subdir in ${subdirs[@]}; do
+    for d in `ls -d ${subdir}/*/`; do
         should_test=false
-        
-        # Override check: Force test if explicitly asked to test all packages
-        if [[ "${TEST_ALL_PACKAGES}" == "true" ]]; then
-            echo "TEST_ALL_PACKAGES is true, forcing execution for ${d}"
-            should_test=true
-        elif [ -n "${GIT_DIFF_ARG}" ]; then
+        if [ -n "${GIT_DIFF_ARG}" ]; then
             echo "checking changes with 'git diff --quiet ${GIT_DIFF_ARG} ${d}'"
             set +e
             git diff --quiet ${GIT_DIFF_ARG} ${d}
@@ -151,4 +120,4 @@ for subdir in "${subdirs[@]}"; do
     done
 done
 
-exit ${RETVAL}
\ No newline at end of file
+exit ${RETVAL}

From 5f5d63b338245a7f7104a07aa3d82aa558241f9f Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 17:34:24 +0000
Subject: [PATCH 04/22] Squashed commit of the following:

commit 73ed7ae60ad15c65232b44813ddd8e10dab965f4
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jul 30 09:58:32 2026 -0700

    experiemting with inner-shard parallel runs

commit 4822342b8047b789c1a35313e8db4ce6cf5593f1
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jul 30 09:58:16 2026 -0700

    dded uv seed to allow pip in venvs

commit f40572c3db62440aed9c9d5f144485810784aeda
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jul 30 09:46:00 2026 -0700

    use uv

commit 7c29040badb6e58881e0fb9ee91982ca1327c3ed
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jul 30 09:45:30 2026 -0700

    obey test all flag in lint checks

commit b5639c6c89390fb64d5607a57fbbd9af57e99e80
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 29 23:37:09 2026 -0700

    fixing mypy check

commit 8816f61cd352d4c6d5eb3d205ebdea19787c55b1
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 29 23:33:15 2026 -0700

    revered back to simpler sharding algorithm

commit c16385f83f46fee2c2d83f72c31fbd0918eaf629
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 29 22:41:43 2026 -0700

    trying different shard algorithm

commit 9bd04b899019ad556b51756f59b276856657fbc2
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 29 21:23:34 2026 -0700

    make sure up to MAX_SHARDS are used

commit 8f12c4e7a3ee5a498b5a347a1c8cb795d3397708
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 29 21:17:24 2026 -0700

    improved sharding algorithnm

commit 4e6f3fc8ef78f83f6e5857358743b685492977ee
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 29 20:39:24 2026 -0700

    group preview packages with main package in shards

commit 36c55dcb76f10ff1ab1bcd41bcefbad70834b81f
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 29 19:07:53 2026 -0700

    adjust how package names are displayed

commit 796eedb45bac8da7f3a45b3c6eed7fbed184300f
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 29 18:53:22 2026 -0700

    improve how multiple package directories are handled

commit 09d705ac110f20b3785a15b37435c81e3eeb2ac1
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 29 16:38:34 2026 -0700

    improved git diff logic for preview packages

commit 4f3b012a546da7e554b0267680ae9a54c44d008e
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 29 16:29:59 2026 -0700

    show preview in shard name for preview packages

commit f8da556cfddbf7b48aebe4eea468925abfa1ea89
Merge: e394b88afd2 2d1372b25b8
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 29 15:52:20 2026 -0700

    Merge branch 'main' into ci_sharding

commit e394b88afd2f45003d025ee5c3266ff1b33abe87
Merge: eefea36070a d328e3b5b3d
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 28 10:35:23 2026 -0700

    Merge branch 'main' into ci_sharding

commit eefea36070a8e153c06a489391bcfe59539fca57
Merge: 7ca01712ccd 53b48ae2bd0
Author: Daniel Sanche <sanche@google.com>
Date:   Mon Jul 27 09:27:26 2026 -0700

    Merge branch 'main' into ci_sharding

commit 7ca01712ccd80ef4df35303ef3166080f799d6c7
Merge: 4e8892cc27b 4f21b8b07ba
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jul 24 16:28:08 2026 -0700

    Merge branch 'main' into ci_sharding

commit 4e8892cc27bec27fabae36e3d089d714d1050481
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 22 12:22:11 2026 -0700

    fixed truncation issues

commit 4382fcc79ba968ad1d6dd601d9c12daf453c1098
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Wed Jul 22 12:15:23 2026 -0700

    added comment

commit 04fb332000408e1ec06b16401670596a1216f2e1
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jul 17 14:15:40 2026 -0700

    changed sqlalchemy-spanner coverage value

commit a05d1fbbe276c159f81257bc93f2fb4f9026629d
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jul 17 11:54:34 2026 -0700

    update spanner coveragerc

commit fb712787098739d3b37ab40f4b3a5d1b4530f9f7
Merge: eaf75e925df 95da740c9ad
Author: Daniel Sanche <sanche@google.com>
Date:   Fri Jul 17 11:53:23 2026 -0700

    Merge branch 'main' into ci_sharding

commit eaf75e925dff8ed4c2ac989a92dbba475cd27c6c
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 13:22:17 2026 -0700

    print only count for successes

commit c70613a661249767c6ebf957177d6cb66810e263
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 13:19:30 2026 -0700

    moved script out of yaml

commit f1eb3a49c2b3c6388afb4ef9b6b5d35d0409fb2f
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 13:14:33 2026 -0700

    added comments to sharding script

commit cf3de20b7c809f12f8eea23b2f1fe16e33145b3f
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 13:10:55 2026 -0700

    added back subdirs

commit d04104d2cd3863d6041b505de42afd16d52c646c
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 13:08:17 2026 -0700

    cleaned up conditional tests

commit e35ea345ca84bcd88300f05506da382f0b48895c
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 12:57:16 2026 -0700

    removed duplication

commit 010e1ad916892f4d9e2f791221e823f9567bb492
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 12:53:49 2026 -0700

    remove empty files

commit a4566cfc182fc3139b4c9a753d03b4a35287fbb0
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 12:53:30 2026 -0700

    use all runtimes in coverage

commit 60a3e74b7811c8feb1467b26f54a365828f568b8
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 12:01:11 2026 -0700

    fixed coverage condition

commit e1bedf12d89955455b4e75999accff249722f0fb
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 11:57:13 2026 -0700

    avoid going over max_shards

commit 6c0566fb4b159df6fd251452918830478e99bcd7
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 10:23:30 2026 -0700

    use 3.10 as lower bound

commit 5bfe2d180cc275684c930e15d213d7db4f49e60a
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 10:19:58 2026 -0700

    only upload coverage for first and last supported version

commit cd33370acb480cdf216e9078833c1d84293f15cc
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 10:00:28 2026 -0700

    undo fast-path optimization

commit fa06713b607146ecb97dff432955a602b7b1daa7
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 09:43:56 2026 -0700

    added fast path for coverage check

commit 45b5e68431264b4085138a152e41e556cbd9d506
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 09:26:09 2026 -0700

    define package weights in yaml

commit e453d2cc03822123f90efa99d37cfc63627eaab7
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 09:21:08 2026 -0700

    added test files

commit e611fe70b9070ba6030491b5474694e90979e4e4
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 09:17:22 2026 -0700

    made max shards configurable

commit da2f41ed6af48ca1f56ea1757e7bab6559cdbff7
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 09:15:52 2026 -0700

    use RAM disk for coverage results

commit 073dc07b536de2fe812f7d705549ba0dd49e7db3
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Tue Jul 7 09:11:02 2026 -0700

    Revert "combine coverage in shards"

    This reverts commit b9f750d3b95b9841391cf0265924f79a0a5b3e4c.

commit b9f750d3b95b9841391cf0265924f79a0a5b3e4c
Author: Daniel Sanche <sanche@google.com>
Date:   Mon Jul 6 22:02:13 2026 -0700

    combine coverage in shards

    Updated the unittest workflow to include coverage installation and combine coverage results for better reporting.

commit b4f9d9d9270246c0787f22ef6320ec9754ad328d
Author: Daniel Sanche <sanche@google.com>
Date:   Mon Jul 6 21:32:36 2026 -0700

    updated find call

commit 15421a74ceebb80fb7feef2c76301d47f46d3003
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 19:05:41 2026 -0700

    removed empty file

commit b20bb1a311f7eb5d9729aa733d1c3b7e391158cf
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 18:58:32 2026 -0700

    enable test against ces

commit deaabe71c1fd59ab2173f9f2ce721d0d978519dd
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 18:50:49 2026 -0700

    fixing bug in coverage search

commit 5cb0e2610ed41a5e91dd8cad14f8047b1842302b
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 18:46:55 2026 -0700

    added pip cache

commit bdc977a5fbb7cb20e8f98e1a49ef625d08173bd5
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 18:32:21 2026 -0700

    end early if fail_under = 0

commit 8ea10ec2851356c45caa151740a841ea381068af
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 18:18:33 2026 -0700

    change MAX_JOBS

commit b4733daf5f58fea85e226a6030040a8c26825ff5
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 18:18:25 2026 -0700

    fix coverage files

commit 964e142e39583be157e3bc7d6a785cc0a38f7dab
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 18:16:36 2026 -0700

    optimized coverage step

commit 80f00617a34de304eca6876991db58603e5d215b
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 16:53:58 2026 -0700

    avoid combining all coverage files

commit e4495b88bc7d82e19913131f4b22036eab330b08
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 16:45:48 2026 -0700

    fixed typo

commit f14d489f3d1f71962ebe36a84f305718ea0222dd
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 15:18:01 2026 -0700

    pack shards alphabetically

commit 2e9bafce26377016a74ae551eb5a34972d9f170e
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 15:11:57 2026 -0700

    added additional weights

commit 7ccca597fc83ce138930fc6d78dd1db578474be4
Merge: 8c4d2ddf05d 6a493903d6d
Author: Daniel Sanche <sanche@google.com>
Date:   Mon Jul 6 14:26:07 2026 -0700

    Merge branch 'main' into ci_sharding

commit 8c4d2ddf05dca98a39acdc615f8cba74e2e671ec
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 14:25:39 2026 -0700

    resolve merge conflict

commit 92626bd5815b50fabb7569f9e8d73bb730c86665
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 14:23:17 2026 -0700

    parallelize final cover check

commit a1fab952cfc5e6999efa3880413670b478529669
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 14:19:16 2026 -0700

    use pacakge weights instead of isolation

commit 89e549918ebb2c174d2c1674bf6bb49a3c4d1711
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 13:16:30 2026 -0700

    changed shard names

commit 40d31e357608aa1e7890df103d7ab17202d10bdb
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 13:12:41 2026 -0700

    isolated shards should be included in max_shard count

commit ee7cabcda9a589a531d32353e6e5c282037220c3
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 12:35:03 2026 -0700

    isolate specific packages

commit c99a693be64913b2e127107af6b3aa60af6f4d20
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 12:27:23 2026 -0700

    increased shard count

commit 6123e7a2965888aef19cc6db03288efbb1d28dd1
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 12:22:47 2026 -0700

    revered unrelated changes

commit fb908604dfbc2bdc5bc0662f1b47d30f12332eef
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 11:48:19 2026 -0700

    don't trigger on label changes

commit 8fb68d3a886ab88fb3b5d185ce3d7ceaa8d1086a
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 11:37:32 2026 -0700

    re-run when label added

commit 6c1be8b5fe54f899d1d534b7dd543ea93dda2498
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Mon Jul 6 11:30:23 2026 -0700

    added github tag to test all packages

commit e34b6543f3a38734688eccffff115536ffb1668f
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jun 18 17:03:08 2026 -0700

    reverted systen test changes

commit 72503de2e4aa8facb73510726551009fb3244f75
Merge: 7b565a4f494 690c15d26f7
Author: Daniel Sanche <sanche@google.com>
Date:   Thu Jun 18 16:59:37 2026 -0700

    Merge branch 'main' into ci_sharding

commit 7b565a4f4941c6159decfdba84394a17db50e9d6
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 19:09:44 2026 -0700

    added no-fail .coveragerc to sqlalchemy-spanner

commit ae05642c77ed529b0a6782fd6e51477b919cb2c3
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 19:09:16 2026 -0700

    added summary to cover step

commit 83ca04a45cc756898ca93ef25dfc5446e1a27eb6
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 18:10:46 2026 -0700

    added known-bad package

commit 886d6d9d9040bb47171de313cc82fef16e195aa3
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 18:07:20 2026 -0700

    unit tests fail if initialize fails

commit cf554cabbf84e1fdc87f38b2e9f096a45892e1ce
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 18:02:52 2026 -0700

    add label to number in shard

commit 9c80a5105d48dce2c60852427b308305d99e549d
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 18:00:18 2026 -0700

    rename tests

commit acdfb1890618a9fa2052d71967e8850f47cd7478
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 17:49:45 2026 -0700

    iterating on shard logic

commit c3cf49eb027638e57cc0f68821ad6e54771b079a
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 17:43:10 2026 -0700

    change shard logic

commit b36b559c0afa45812f9e4ab094b70ba6e3e85be6
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 17:35:40 2026 -0700

    fixed typo

commit a5cc4979647c3c353f8cbcd8c0c4131bc7a7a98b
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 17:29:36 2026 -0700

    activated 11th package (enable sharding)

commit 980d8eb2bb2f0e4f4a69946ab639d4fd98dcc135
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 17:10:15 2026 -0700

    change default for coverage percent

commit 363308980061fa18dfff9ae63fe801e5613b1120
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 17:07:00 2026 -0700

    10 packages total

commit 7bb323ceb3bf4b25af8903874e460f1c0b0f17c6
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 16:43:46 2026 -0700

    activated more packages

commit b00967f00800ad6b41a887ec7d1112bddc8c594d
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 15:17:58 2026 -0700

    loosen firestore coverage requirement

commit cf1a1f16dd823558c00148e01f997e280a4fd38c
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 15:12:07 2026 -0700

    use individual coverage checks

commit 71f444a03dca196b8984321de2ec65c9e2093b26
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 13:55:50 2026 -0700

    fail fast

commit a0f5c9ada55a7b0c544d807e0e3d4b4311497a6b
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 13:50:18 2026 -0700

    allow hidden files for cover

commit 1cd8c1f5baf462387d22408d013577d9eb882119
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 13:28:15 2026 -0700

    attempt fix for cover

commit c49b06d884e554ef0eca578606afd3fe871bf8c5
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 13:17:10 2026 -0700

    attempt cover fix

commit ff1274f39f8f29c5c13663753c3fa83e1cb12e78
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 12:37:01 2026 -0700

    remove global run on ci/ change

commit 32968a9a2222b9414574b0f8e1d8d26f6f0bcf95
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 12:33:23 2026 -0700

    add shard descriptions

commit 8b825d5a645184860009b3dffef65c82c08d7109
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 12:20:49 2026 -0700

    updated lint and mypy logic

commit fd5792d883aa05ebbaee275130ccb8d65acc64cc
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 12:20:31 2026 -0700

    removed many SHARD_TEST files

commit e6167bd04f929910b111b3787cbdc52788714d35
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 11:43:25 2026 -0700

    system tests print all logs in main build log

commit 6e3531dc303bb7ae4811b3cd9d3e004897366241
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 11:25:24 2026 -0700

    removed sqlalchemy-spanner from touched packages

commit 46d158345fa4fad1d12b96177f6d6c3daa015b68
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 11:19:01 2026 -0700

    fixed lint/mypy runs

commit de74a685007361f9e100253f768015a6c6e190a6
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 10:42:56 2026 -0700

    update sharding logic

commit d8dd522a1557ddc070a95ed01bbcbe65bbb7b5a4
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 10:38:34 2026 -0700

    update system tests to show logs for each target

commit 49cac0fe1f782ef8b88601b635fdc7722a7855bf
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 10:35:12 2026 -0700

    attempt fix for lint

commit 15916dfd86f16f8b1ce71a8c9bbe2b92bb11d714
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Fri Jun 12 09:26:18 2026 -0700

    split out system test logs

commit af4d10c45b1de758d51eb56e3089ec7e22676965
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jun 11 21:33:04 2026 -0700

    fix system tests

commit a450254f883140d649ec98cad9fb61ce453c6ef5
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jun 11 19:01:06 2026 -0700

    fix coverage

commit 74f1ef7d22f12d93ee2712b91e374f0af9406db7
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jun 11 17:36:13 2026 -0700

    fixed tests

commit 73ab0915ed3d3f22e90ef398e59e1a27b5508698
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jun 11 17:31:58 2026 -0700

    changed shard params

commit 3c8d0577061dfab9008afffd39f8f58a6f1556b1
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jun 11 17:29:10 2026 -0700

    added unit-complete to gather all shards

commit 02c765377413efc0cc9b807f411f157ff03439e7
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jun 11 17:25:15 2026 -0700

    added sharding test file

commit 9ad0f0c2abb24862dbbd6ea8e1212130acf12b5d
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jun 11 17:24:57 2026 -0700

    added changes to many packages for testing

commit a7502d4e8a0969010a2eb6a641092a9e879326f9
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jun 11 17:21:14 2026 -0700

    run system tests concurrently

commit 01d47536522c5082127757b8d28fea529e6752be
Author: Daniel Sanche <d.sanche14@gmail.com>
Date:   Thu Jun 11 17:21:04 2026 -0700

    added unit test sharding
---
 .github/workflows/lint.yml         |  29 +++-
 .github/workflows/unittest.yml     | 205 ++++++++++++-------------
 ci/get_package_shards.py           | 231 +++++++++++++++++++++++++++++
 ci/report_coverage.sh              | 164 ++++++++++++++++++++
 ci/run_conditional_tests.sh        | 160 +++++++++++---------
 packages/google-crc32c/.coveragerc |   2 +-
 6 files changed, 623 insertions(+), 168 deletions(-)
 create mode 100644 ci/get_package_shards.py
 create mode 100755 ci/report_coverage.sh

diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index 129fc766458c..e7fb1fec6a0c 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -12,6 +12,12 @@ name: lint
 permissions:
   contents: read
 
+env:
+  NOX_REUSE_EXISTING_VIRTUALENVS: "true"
+  NOX_ENVDIR: "/tmp/shared_nox_envs"
+  NOX_DEFAULT_VENV_BACKEND: "uv"
+  UV_VENV_SEED: "1"
+
 jobs:
   lint:
     runs-on: ubuntu-latest
@@ -24,6 +30,14 @@ jobs:
       with:
         fetch-depth: 2
         persist-credentials: false
+    - name: Check for unit_test:all_packages label
+      id: check-label
+      run: |
+        if [[ "${{ contains(github.event.pull_request.labels.*.name, 'unit_test:all_packages') }}" == "true" ]]; then
+          echo "is_full_run=true" >> $GITHUB_OUTPUT
+        else
+          echo "is_full_run=false" >> $GITHUB_OUTPUT
+        fi
     - name: Setup Python
       uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6
       with:
@@ -31,11 +45,12 @@ jobs:
     - name: Install nox
       run: |
         python -m pip install --upgrade setuptools pip wheel
-        python -m pip install nox
+        python -m pip install nox uv
     - name: Run lint
       env:
         BUILD_TYPE: presubmit
         TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
+        TEST_ALL_PACKAGES: ${{ steps.check-label.outputs.is_full_run }}
         TEST_TYPE: lint
         # TODO(https://github.com/googleapis/google-cloud-python/issues/13775): Specify `PY_VERSION` rather than relying on the default python version of the nox session.
         PY_VERSION: "unused"
@@ -45,6 +60,7 @@ jobs:
       env:
         BUILD_TYPE: presubmit
         TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
+        TEST_ALL_PACKAGES: ${{ steps.check-label.outputs.is_full_run }}
         TEST_TYPE: lint_setup_py
         # TODO(https://github.com/googleapis/google-cloud-python/issues/13775): Specify `PY_VERSION` rather than relying on the default python version of the nox session.
         PY_VERSION: "unused"
@@ -61,6 +77,14 @@ jobs:
       with:
         fetch-depth: 2
         persist-credentials: false
+    - name: Check for unit_test:all_packages label
+      id: check-label
+      run: |
+        if [[ "${{ contains(github.event.pull_request.labels.*.name, 'unit_test:all_packages') }}" == "true" ]]; then
+          echo "is_full_run=true" >> $GITHUB_OUTPUT
+        else
+          echo "is_full_run=false" >> $GITHUB_OUTPUT
+        fi
     - name: Setup Python
       uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6
       with:
@@ -68,11 +92,12 @@ jobs:
     - name: Install nox
       run: |
         python -m pip install --upgrade setuptools pip wheel
-        python -m pip install nox
+        python -m pip install nox uv
     - name: Run mypy
       env:
         BUILD_TYPE: presubmit
         TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
+        TEST_ALL_PACKAGES: ${{ steps.check-label.outputs.is_full_run }}
         TEST_TYPE: mypy
         # TODO(https://github.com/googleapis/google-cloud-python/issues/13775): Specify `PY_VERSION` rather than relying on the default python version of the nox session.
         PY_VERSION: "unused"
diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 392f5ece6270..196359ddf6e6 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -12,13 +12,76 @@ name: unittest
 permissions:
   contents: read
 
+env:
+  PACKAGE_DIRS: packages preview-packages
+  NOX_REUSE_EXISTING_VIRTUALENVS: "true"
+  NOX_ENVDIR: "/tmp/shared_nox_envs"
+  NOX_DEFAULT_VENV_BACKEND: "uv"
+  UV_VENV_SEED: "1"
+
 jobs:
+  initialize:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+      is_full_run: ${{ steps.check-label.outputs.is_full_run }}
+    env:
+      MAX_SHARDS: 20
+      # Define weights for long-running unit tests to balance shard execution time
+      # Each weight is roughly 1 minute of expected execution time
+      # Default for unset packages is 1
+      PACKAGE_WEIGHTS: |
+        bigframes: 6
+        google-ai-generativelanguage: 4
+        google-auth: 5
+        google-cloud-compute: 12
+        google-cloud-compute-v1beta: 12
+        google-cloud-dialogflow: 6
+        google-cloud-dialogflow-cx: 6
+        google-cloud-discoveryengine: 8
+        google-cloud-retail: 5
+        google-shopping-merchant-accounts: 4
+    steps:
+    - name: Checkout
+      uses: actions/checkout@v4
+      with:
+        fetch-depth: 2
+    - name: Check for unit_test:all_packages label
+      id: check-label
+      run: |
+        if [[ "${{ contains(github.event.pull_request.labels.*.name, 'unit_test:all_packages') }}" == "true" ]]; then
+          echo "is_full_run=true" >> $GITHUB_OUTPUT
+        else
+          echo "is_full_run=false" >> $GITHUB_OUTPUT
+        fi
+    - name: Setup Python
+      uses: actions/setup-python@v5
+      with:
+        python-version: "3.10"
+    - name: Get package shards
+      id: set-matrix
+      env:
+        BUILD_TYPE: presubmit
+        TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
+        TEST_ALL_PACKAGES: ${{ steps.check-label.outputs.is_full_run }}
+        MAX_SHARDS: ${{ env.MAX_SHARDS }}
+        PACKAGE_WEIGHTS: ${{ env.PACKAGE_WEIGHTS }}
+      run: |
+        if [ -n "$TARGET_BRANCH" ]; then
+          git fetch origin "$TARGET_BRANCH" --depth=1 || true
+        fi
+        python3 ci/get_package_shards.py
+
   unit:
+    needs: initialize
+    if: needs.initialize.outputs.matrix != '[]' && needs.initialize.outputs.matrix != ''
     runs-on: ubuntu-22.04
     strategy:
       fail-fast: true
       matrix:
         python: ['3.10', "3.11", "3.12", "3.13", "3.14"]
+        package_shard: ${{ fromJson(needs.initialize.outputs.matrix) }}
+    name: ${{ matrix.package_shard.is_sharded && format('unit ({0}, {1})', matrix.python, matrix.package_shard.name) || format('unit ({0})', matrix.python) }}
     steps:
     - name: Checkout
       uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
@@ -32,30 +95,51 @@ jobs:
       uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6
       with:
         python-version: ${{ matrix.python }}
+        cache: 'pip'
     - name: Install nox
       run: |
         python -m pip install --upgrade setuptools pip wheel
-        python -m pip install nox
-    - name: Run unit tests
+        python -m pip install nox uv
+    - name: Run unit tests for ${{ matrix.package_shard.description }}
       env:
-        COVERAGE_FILE: ${{ github.workspace }}/.coverage-${{ matrix.python }}
         BUILD_TYPE: presubmit
         TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
         TEST_TYPE: unit
         PY_VERSION: ${{ matrix.python }}
+        PACKAGE_LIST: ${{ matrix.package_shard.packages }}
       run: |
         ci/run_conditional_tests.sh
     - name: Upload coverage results
       uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4
       with:
-        name: coverage-artifact-${{ matrix.python }}
-        path: .coverage-${{ matrix.python }}
+        name: coverage-artifact-${{ matrix.python }}-${{ matrix.package_shard.index }}
+        path: .coverage.${{ matrix.python }}.*
         include-hidden-files: true
 
+  all-tests:
+    needs: [initialize, unit]
+    if: always()
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check unit test results
+        run: |
+          # 1. Check initialize job
+          if [[ "${{ needs.initialize.result }}" != "success" ]]; then
+            echo "Error: The initialize job status was: ${{ needs.initialize.result }}"
+            exit 1
+          fi
+          # 2. Check unit test shards
+          if [[ "${{ needs.unit.result }}" != "success" && "${{ needs.unit.result }}" != "skipped" ]]; then
+            echo "Unit tests failed"
+            exit 1
+          fi
+          echo "All unit tests passed or were skipped"
+
   cover:
     runs-on: ubuntu-latest
     needs:
         - unit
+        - initialize
     steps:
     - name: Checkout
       uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4.3.1
@@ -71,10 +155,18 @@ jobs:
         python-version: "3.10"
     - name: Set number of files changes in packages and preview-packages directories
       id: packages
+      env:
+        TEST_ALL_PACKAGES: ${{ needs.initialize.outputs.is_full_run }}
+        TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
       run: |
-        git diff HEAD~1 -- packages preview-packages > /dev/null
-        num_files_changed=$(git diff HEAD~1 -- packages preview-packages | wc -l | tr -d ' ')
-        echo "num_files_changed=${num_files_changed}" >> "$GITHUB_OUTPUT"
+        if [[ "${TEST_ALL_PACKAGES}" == "true" ]]; then
+          echo "num_files_changed=1" >> "$GITHUB_OUTPUT"
+        else
+          TARGET_BRANCH="${TARGET_BRANCH:-main}"
+          git fetch origin "$TARGET_BRANCH" --depth=1 || true
+          num_files_changed=$(git diff --name-only "origin/${TARGET_BRANCH}" -- ${PACKAGE_DIRS} | wc -l | tr -d ' ')
+          echo "num_files_changed=${num_files_changed}" >> "$GITHUB_OUTPUT"
+        fi
     - name: Install coverage
       if: ${{ steps.packages.outputs.num_files_changed > 0 }}
       run: |
@@ -84,101 +176,16 @@ jobs:
       if: ${{ steps.packages.outputs.num_files_changed > 0 }}
       uses: actions/download-artifact@634f93cb2916e3fdff6788551b99b062d0335ce0 # v5
       with:
-        path: .coverage-results/
+        path: /dev/shm/.coverage-results/
+        merge-multiple: true
     - name: Report coverage results
       if: ${{ steps.packages.outputs.num_files_changed > 0 }}
       env:
         # TODO: default to 100% coverage after next gapic-generator release
         # https://github.com/googleapis/google-cloud-python/issues/17459
         DEFAULT_FAIL_UNDER: 99
+        TEST_ALL_PACKAGES: ${{ needs.initialize.outputs.is_full_run }}
+        TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
+        BUILD_TYPE: presubmit
       run: |
-        # Find all modified packages
-        modified_packages=$(git diff --name-only HEAD~1 -- packages preview-packages | cut -d/ -f1,2 | sort -u)
-
-        existing_modified_packages=()
-        for pkg in ${modified_packages}; do
-          if [ -d "${pkg}" ]; then
-            existing_modified_packages+=("${pkg}")
-          fi
-        done
-
-        if [ ${#existing_modified_packages[@]} -eq 0 ]; then
-          echo "All modified packages were deleted. Skipping coverage evaluation."
-          exit 0
-        fi
-
-        if [ -d .coverage-results ]; then
-          # Unzip any zipped coverage results
-          find .coverage-results -type f -name '*.zip' -exec unzip -o {} \;
-
-          # Find all coverage files and combine them.
-          # We find files starting with .coverage (excluding .coveragerc files and templates)
-          coverage_files=$(find .coverage-results . -type f -name '.coverage*' ! -name '.coveragerc*')
-          if [ -n "${coverage_files}" ]; then
-            coverage combine ${coverage_files}
-          else
-            echo "Error: No coverage files found to combine."
-            exit 1
-          fi
-
-          # Find all modified packages
-          modified_packages=$(git diff --name-only HEAD~1 -- packages preview-packages | cut -d/ -f1,2 | sort -u)
-
-          failed_packages=()
-          passed_packages=()
-
-          for pkg in ${modified_packages}; do
-            if [ -d "${pkg}" ]; then
-              echo "============================================================"
-              echo "Evaluating coverage for package: ${pkg}"
-              echo "============================================================"
-
-              set +e
-              pushd "${pkg}" > /dev/null
-              if [ -f ".coveragerc" ]; then
-                echo "Using package-specific configuration: ${pkg}/.coveragerc"
-                # If fail_under is specified in the package-specific .coveragerc, coverage report
-                # will automatically enforce it. Otherwise, we enforce the default.
-                if grep -q "fail_under" ".coveragerc"; then
-                  COVERAGE_FILE=../../.coverage coverage report --include="$PWD/**"
-                else
-                  echo "No fail_under specified in ${pkg}/.coveragerc, enforcing default"
-                  COVERAGE_FILE=../../.coverage coverage report --include="$PWD/**" --fail-under="${DEFAULT_FAIL_UNDER}"
-                fi
-              else
-                echo "No .coveragerc found for ${pkg}, enforcing default"
-                COVERAGE_FILE=../../.coverage coverage report --include="$PWD/**" --fail-under="${DEFAULT_FAIL_UNDER}"
-              fi
-              status=$?
-              popd > /dev/null
-              set -e
-
-              if [ ${status} -ne 0 ]; then
-                failed_packages+=("${pkg}")
-              else
-                passed_packages+=("${pkg}")
-              fi
-            fi
-          done
-
-          echo "============================================================"
-          echo "Coverage Evaluation Summary"
-          echo "============================================================"
-          if [ ${#passed_packages[@]} -gt 0 ]; then
-            echo "Passed packages:"
-            for pkg in "${passed_packages[@]}"; do
-              echo "  - ${pkg}"
-            done
-          fi
-          if [ ${#failed_packages[@]} -gt 0 ]; then
-            echo "Failed packages:"
-            for pkg in "${failed_packages[@]}"; do
-              echo "  - ${pkg}"
-            done
-            exit 1
-          fi
-        else
-          echo "Error: No coverage results were downloaded from the unit test jobs."
-          echo "This usually means the unit tests did not run or failed to upload their coverage files."
-          exit 1
-        fi
+        ci/report_coverage.sh
diff --git a/ci/get_package_shards.py b/ci/get_package_shards.py
new file mode 100644
index 000000000000..27c4ea6aa1f0
--- /dev/null
+++ b/ci/get_package_shards.py
@@ -0,0 +1,231 @@
+# Copyright 2026 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
+#
+#      http://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.
+
+"""Script to group changed packages into balanced shards for CI testing.
+
+This script identifies which packages have changed compared to a target branch
+(or since the last commit) and groups them into a fixed number of shards.
+It uses package weights (configured via environment variables) to balance the
+execution time across shards while maintaining alphabetical order and
+contiguous grouping. All directory variants of a package (e.g. packages/foo and
+preview-packages/foo) are kept aligned in the exact same shard.
+"""
+
+import os
+import subprocess
+import json
+import math
+import sys
+import collections
+
+
+def get_package_directories():
+    """Parses package directory roots from the PACKAGE_DIRS environment variable.
+
+    Defaults to ['packages', 'preview-packages'] if not set.
+    """
+    env_dirs = os.environ.get("PACKAGE_DIRS", "")
+    if env_dirs:
+        dirs = [d.strip() for d in env_dirs.replace('\n', ' ').split(' ') if d.strip()]
+        if dirs:
+            return dirs
+    return ["packages", "preview-packages"]
+
+
+def get_package_weights():
+    """Parses package weights from the PACKAGE_WEIGHTS environment variable.
+    Package weights represent the relative size of the test, where the weight
+    approximately represents the minutes the test takes to run. This is used
+    for distributing work properly across shards.
+
+    The environment variable is expected to be a multiline string where each line
+    is in the format 'package_name: weight'. Lines starting with '#' are ignored.
+
+    Returns:
+        dict: A mapping of package names to their integer weights.
+    """
+    weights = {}
+    env_weights = os.environ.get("PACKAGE_WEIGHTS", "")
+    for line in env_weights.splitlines():
+        line = line.strip()
+        if not line or line.startswith("#"):
+            continue
+        if ":" in line:
+            try:
+                pkg, weight = line.split(":", 1)
+                weights[pkg.strip()] = int(weight.strip())
+            except ValueError:
+                continue
+    return weights
+
+
+def get_packages():
+    """Lists all package directory paths in the repository grouped by package name.
+
+    Returns:
+        dict: A dictionary mapping package_name -> list of relative directory paths.
+    """
+    subdirs = get_package_directories()
+    packages_map = collections.defaultdict(list)
+    for subdir in subdirs:
+        if not os.path.exists(subdir):
+            continue
+        for d in os.listdir(subdir):
+            full_path = os.path.join(subdir, d) + '/'
+            if os.path.isdir(full_path):
+                packages_map[d].append(full_path)
+    return packages_map
+
+
+def get_packages_to_test():
+    """Determines the dictionary of package names to directory paths that need to be tested.
+
+    This is based on git diffs against the target branch (presubmit) or the
+    previous commit (continuous). If TEST_ALL_PACKAGES is set to true,
+    all packages are returned.
+
+    Returns:
+        dict: A dictionary mapping package_name -> list of relative directory paths to be tested.
+    """
+    build_type = os.environ.get('BUILD_TYPE', 'presubmit')
+    target_branch = os.environ.get('TARGET_BRANCH', 'main')
+    test_all_packages = os.environ.get('TEST_ALL_PACKAGES', 'false').lower() == 'true'
+
+    all_packages = get_packages()
+
+    if test_all_packages:
+        return all_packages
+
+    if build_type == 'presubmit':
+        git_diff_arg = f"origin/{target_branch}"
+    elif build_type == 'continuous':
+        git_diff_arg = "HEAD~1.."
+    else:
+        return all_packages
+
+    try:
+        res = subprocess.check_output(['git', 'diff', '--name-only', git_diff_arg]).decode('utf-8')
+        changed_files = res.splitlines()
+    except subprocess.CalledProcessError:
+        # If change detection fails, fall back to all packages
+        return all_packages
+
+    package_dirs = set(get_package_directories())
+    to_test_names = set()
+    for f in changed_files:
+        parts = f.split('/')
+        if len(parts) >= 2 and parts[0] in package_dirs:
+            pkg_name = parts[1]
+            if pkg_name in all_packages:
+                to_test_names.add(pkg_name)
+
+    return {name: all_packages[name] for name in to_test_names}
+
+
+def group_packages(packages_map):
+    """Groups packages by package name into balanced shards.
+
+    All directory variants of a package (e.g. packages/foo and preview-packages/foo)
+    are kept together in the exact same shard.
+
+    Args:
+        packages_map (dict): Dictionary mapping package_name -> list of directory paths.
+
+    Returns:
+        list: A list of dictionaries, each representing a shard with its name,
+              index, description, and the space-separated list of packages.
+    """
+    if not packages_map:
+        return []
+
+    package_weights_map = get_package_weights()
+    sorted_pkg_names = sorted(packages_map.keys())
+
+    pkg_items = []
+    total_weight = 0
+    for name in sorted_pkg_names:
+        paths = packages_map[name]
+        # Multiply base weight by number of directory variants (e.g. standard + preview)
+        weight = package_weights_map.get(name, 1) * len(paths)
+        pkg_items.append((name, paths, weight))
+        total_weight += weight
+
+    # Dynamically determine target weight to balance across max shards.
+    max_shards = int(os.environ.get("MAX_SHARDS", 16))
+    target_weight = max(10, math.ceil(total_weight / max_shards))
+
+    shards_list = []
+    current_shard_items = []
+    current_shard_weight = 0
+
+    # Pack packages alphabetically by package name.
+    for name, paths, weight in pkg_items:
+        # If adding this package would exceed target weight AND we haven't reached the 
+        # shard limit, start a new shard. Otherwise, keep "stuffing" the current one.
+        if current_shard_items and (current_shard_weight + weight > target_weight) and len(shards_list) < max_shards - 1:
+            shards_list.append(current_shard_items)
+            current_shard_items = [(name, paths, weight)]
+            current_shard_weight = weight
+        else:
+            current_shard_items.append((name, paths, weight))
+            current_shard_weight += weight
+
+    if current_shard_items:
+        shards_list.append(current_shard_items)
+
+    # Construct the final shards output list
+    shards = []
+    for i, shard_items in enumerate(shards_list):
+        index = i + 1
+        name = f"Shard {index}"
+        num_in_shard = len(shard_items)
+
+        # Calculate contiguous range description using package names
+        first_pkg_name = shard_items[0][0]
+        last_pkg_name = shard_items[-1][0]
+        if num_in_shard == 1:
+            desc = first_pkg_name
+        else:
+            desc = f"{first_pkg_name}...{last_pkg_name} ({num_in_shard} packages)"
+
+        all_paths = []
+        for _, paths, _ in shard_items:
+            all_paths.extend(paths)
+
+        shards.append({
+            "name": name,
+            "index": index,
+            "description": desc,
+            "packages": " ".join(all_paths),
+            "is_sharded": True
+        })
+
+    # Set is_sharded dynamically based on the total number of shards
+    total_shards = len(shards)
+    for shard in shards:
+        shard["is_sharded"] = total_shards > 1
+
+    return shards
+
+
+if __name__ == "__main__":
+    packages = get_packages_to_test()
+    shards = group_packages(packages)
+    shards_json = json.dumps(shards)
+    print(shards_json)
+
+    github_output = os.environ.get("GITHUB_OUTPUT")
+    if github_output:
+        with open(github_output, "a") as f:
+            f.write(f"matrix={shards_json}\n")
diff --git a/ci/report_coverage.sh b/ci/report_coverage.sh
new file mode 100755
index 000000000000..f204bc45cdcc
--- /dev/null
+++ b/ci/report_coverage.sh
@@ -0,0 +1,164 @@
+#!/bin/bash
+# Copyright 2026 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
+#
+#      http://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.
+
+set -eo pipefail
+
+# This script generates coverage reports for modified packages.
+# It assumes coverage databases have been downloaded to RESULTS_DIR.
+# It uses /dev/shm for high-performance processing.
+
+RESULTS_DIR="${RESULTS_DIR:-/dev/shm/.coverage-results}"
+LOG_DIR="/dev/shm/coverage-logs"
+DEFAULT_FAIL_UNDER="${DEFAULT_FAIL_UNDER:-99}"
+MAX_JOBS=$(nproc)
+
+mkdir -p "${LOG_DIR}"
+
+if [ ! -d "${RESULTS_DIR}" ]; then
+    echo "Error: No coverage results found in ${RESULTS_DIR}."
+    exit 1
+fi
+
+# Unzip any zipped coverage results
+find "$RESULTS_DIR" -type f -name '*.zip' -print0 | xargs -0 -P "${MAX_JOBS}" -I {} unzip -q -o {} -d "$RESULTS_DIR"
+
+# Identify modified packages
+BUILD_TYPE="${BUILD_TYPE:-presubmit}"
+TARGET_BRANCH="${TARGET_BRANCH:-main}"
+
+PACKAGE_DIRS="${PACKAGE_DIRS:-packages preview-packages}"
+
+if [[ "${TEST_ALL_PACKAGES}" == "true" ]]; then
+    # Test all packages mode: evaluate coverage for every package in the repository
+    modified_packages=$(for dir in ${PACKAGE_DIRS}; do ls -d ${dir}/*/ 2>/dev/null; done | cut -d/ -f1,2 | sort -u)
+elif [[ "${BUILD_TYPE}" == "presubmit" ]]; then
+    # Presubmit build: evaluate coverage only for packages modified relative to the target branch
+    modified_packages=$(git diff --name-only "origin/${TARGET_BRANCH}" -- ${PACKAGE_DIRS} 2>/dev/null | cut -d/ -f1,2 | sort -u)
+else
+    # Continuous build (post-merge on main): evaluate coverage for packages modified in the last commit
+    modified_packages=$(git diff --name-only HEAD~1 -- ${PACKAGE_DIRS} 2>/dev/null | cut -d/ -f1,2 | sort -u)
+fi
+
+# Function to report coverage for a single package
+report_package_coverage() {
+    local pkg=$1
+    local pkg_name_clean=$(echo "${pkg}" | sed 's|/$||' | sed 's|/|_|g')
+    local pkg_log="${LOG_DIR}/${pkg_name_clean}.log"
+    local pkg_status="${LOG_DIR}/${pkg_name_clean}.status"
+    
+    # Use /dev/shm for the combined coverage file to reduce disk I/O
+    local pkg_coverage_db="/dev/shm/.coverage.${pkg_name_clean}"
+
+    set +e
+    (
+        # Find coverage databases belonging specifically to this package
+        shopt -s nullglob
+        local pkg_files=(
+            "${RESULTS_DIR}/.coverage."*"."${pkg_name_clean}
+            "${RESULTS_DIR}/.coverage."*"."${pkg_name_clean}"."*
+            "${RESULTS_DIR}"/*/".coverage."*"."${pkg_name_clean}
+            "${RESULTS_DIR}"/*/".coverage."*"."${pkg_name_clean}"."*
+        )
+        shopt -u nullglob
+
+        # Handle explicit skip via .coveragerc
+        if [ -f "${pkg}/.coveragerc" ] && grep -Eq "fail_under\s*=\s*0" "${pkg}/.coveragerc"; then
+            echo "Package has fail_under = 0, passing instantly with 100% success (even without coverage files)" > "${pkg_log}"
+            echo 0 > "${pkg_status}"
+            return
+        fi
+
+        if [ ${#pkg_files[@]} -eq 0 ]; then
+            echo "Warning: No coverage results found for ${pkg}" > "${pkg_log}"
+            echo 1 > "${pkg_status}"
+            return
+        fi
+
+        pushd "${pkg}" > /dev/null
+
+        # Combine databases
+        COVERAGE_FILE="${pkg_coverage_db}" coverage combine "${pkg_files[@]}" >> "${pkg_log}" 2>&1
+
+        # Generate report
+        if [ -f ".coveragerc" ]; then
+            echo "Using package-specific configuration: ${pkg}/.coveragerc" >> "${pkg_log}"
+            if grep -q "fail_under" ".coveragerc"; then
+                COVERAGE_FILE="${pkg_coverage_db}" coverage report --rcfile=".coveragerc" --include="$PWD/**" >> "${pkg_log}" 2>&1
+            else
+                echo "No fail_under specified in ${pkg}/.coveragerc, enforcing default" >> "${pkg_log}"
+                COVERAGE_FILE="${pkg_coverage_db}" coverage report --rcfile=".coveragerc" --include="$PWD/**" --fail-under="${DEFAULT_FAIL_UNDER}" >> "${pkg_log}" 2>&1
+            fi
+        else
+            echo "No .coveragerc found for ${pkg}, enforcing default" >> "${pkg_log}"
+            COVERAGE_FILE="${pkg_coverage_db}" coverage report --include="$PWD/**" --fail-under="${DEFAULT_FAIL_UNDER}" >> "${pkg_log}" 2>&1
+        fi
+        
+        echo $? > "${pkg_status}"
+        popd > /dev/null
+    )
+    set -e
+}
+
+# Run coverage reporting in parallel
+for pkg in ${modified_packages}; do
+    if [ -d "${pkg}" ]; then
+        # Limit concurrent jobs
+        while [ $(jobs -r | wc -l) -ge "${MAX_JOBS}" ]; do
+            sleep 0.1
+        done
+        report_package_coverage "${pkg}" &
+    fi
+done
+
+wait
+
+# Summary and exit
+failed_packages=()
+passed_packages=()
+
+for pkg in ${modified_packages}; do
+    if [ -d "${pkg}" ]; then
+        pkg_name_clean=$(echo "${pkg}" | sed 's|/$||' | sed 's|/|_|g')
+        pkg_log="${LOG_DIR}/${pkg_name_clean}.log"
+        pkg_status="${LOG_DIR}/${pkg_name_clean}.status"
+
+        echo "============================================================"
+        echo "Evaluating coverage for package: ${pkg}"
+        echo "============================================================"
+        [ -f "${pkg_log}" ] && cat "${pkg_log}"
+
+        status=$(cat "${pkg_status}" 2>/dev/null || echo 1)
+        if [ "${status}" -ne 0 ]; then
+            failed_packages+=("${pkg}")
+        else
+            passed_packages+=("${pkg}")
+        fi
+    fi
+done
+
+echo "============================================================"
+echo "Coverage Evaluation Summary"
+echo "============================================================"
+if [ ${#passed_packages[@]} -gt 0 ]; then
+    echo "✅ Passed: ${#passed_packages[@]} packages"
+fi
+
+if [ ${#failed_packages[@]} -gt 0 ]; then
+    echo "❌ Failed: ${#failed_packages[@]} packages"
+    for pkg in "${failed_packages[@]}"; do
+        echo "  - ${pkg}"
+    done
+    exit 1
+fi
diff --git a/ci/run_conditional_tests.sh b/ci/run_conditional_tests.sh
index b4df9cb923f4..9901711aee1a 100755
--- a/ci/run_conditional_tests.sh
+++ b/ci/run_conditional_tests.sh
@@ -47,77 +47,105 @@ git config --global url."${PROJECT_ROOT}".insteadOf "https://github.com/googleap
 # A script file for running the test in a sub project.
 test_script="${PROJECT_ROOT}/ci/run_single_test.sh"
 
-if [[ ${BUILD_TYPE} == "presubmit" ]]; then
-    # For presubmit build, we want to know the difference from the
-    # common commit in the target branch.
-    GIT_DIFF_ARG="origin/$TARGET_BRANCH..."
-
-    # Then fetch enough history for finding the common commit.
-    git fetch origin "$TARGET_BRANCH" --deepen=200
-
-elif [[ ${BUILD_TYPE} == "continuous" ]]; then
-    # For continuous build, we want to know the difference in the last
-    # commit. This assumes we use squash commit when merging PRs.
-    GIT_DIFF_ARG="HEAD~.."
-
-    # Then fetch one last commit for getting the diff.
-    git fetch origin "$TARGET_BRANCH" --deepen=1
-
-else
-    # Run everything.
-    GIT_DIFF_ARG=""
-fi
-
-# Then detect changes in the test scripts.
-
-set +e
-git diff --quiet ${GIT_DIFF_ARG} ci
-changed=$?
-set -e
-
-# Now we have a fixed list, but we can change it to autodetect if
-# necessary.
-
-subdirs=(
-    packages
-    preview-packages
-)
-
+# Global exit code tracker
 RETVAL=0
 
-for subdir in ${subdirs[@]}; do
-    for d in `ls -d ${subdir}/*/`; do
-        should_test=false
-        if [ -n "${GIT_DIFF_ARG}" ]; then
-            echo "checking changes with 'git diff --quiet ${GIT_DIFF_ARG} ${d}'"
-            set +e
-            git diff --quiet ${GIT_DIFF_ARG} ${d}
-            changed=$?
-            set -e
-            if [[ "${changed}" -eq 0 ]]; then
-                echo "no change detected in ${d}, skipping"
+# Shared test execution logic
+run_test_in_dir() {
+    local d=$1
+    local pkg_name_clean=$(echo ${d} | sed 's|/$||' | sed 's|/|_|g')
+    local log_file="/tmp/test_log_${PY_VERSION}_${pkg_name_clean}.log"
+    export COVERAGE_FILE="${PROJECT_ROOT}/.coverage.${PY_VERSION}.${pkg_name_clean}"
+
+    pushd ${d} > /dev/null
+
+    # Temporarily allow failure.
+    set +e
+    ${test_script} > "${log_file}" 2>&1
+    local ret=$?
+    set -e
+
+    popd > /dev/null
+
+    # Atomically print complete package log block so parallel outputs never interleave
+    {
+        echo "============================================================"
+        echo "Running tests in ${d}"
+        echo "============================================================"
+        cat "${log_file}"
+        rm -f "${log_file}"
+    }
+
+    if [ ${ret} -ne 0 ]; then
+        exit ${ret}
+    fi
+}
+
+export -f run_test_in_dir
+export test_script PROJECT_ROOT PY_VERSION TEST_TYPE
+
+dirs_to_test=()
+
+if [ -n "${PACKAGE_LIST}" ]; then
+    echo "Using provided PACKAGE_LIST"
+    for d in ${PACKAGE_LIST}; do
+        dirs_to_test+=("${d}")
+    done
+else
+    if [ "${TEST_ALL_PACKAGES}" = "true" ]; then
+        GIT_DIFF_ARG=""
+
+    elif [[ ${BUILD_TYPE} == "presubmit" ]]; then
+        # For presubmit build, we want to know the difference from the target branch.
+        TARGET_BRANCH="${TARGET_BRANCH:-main}"
+        if [ -n "${TARGET_BRANCH}" ]; then
+            git fetch origin "${TARGET_BRANCH}" --depth=1 || true
+        fi
+        GIT_DIFF_ARG="origin/${TARGET_BRANCH}"
+
+    elif [[ ${BUILD_TYPE} == "continuous" ]]; then
+        # For continuous build, we want to know the difference in the last
+        # commit. This assumes we use squash commit when merging PRs.
+        GIT_DIFF_ARG="HEAD~1.."
+
+    else
+        # Run everything.
+        GIT_DIFF_ARG=""
+    fi
+
+    subdirs=(${PACKAGE_DIRS:-packages preview-packages})
+
+    for subdir in ${subdirs[@]}; do
+        if [ ! -d "${subdir}" ]; then continue; fi
+        for d in `ls -d ${subdir}/*/ 2>/dev/null`; do
+            should_test=false
+            if [ -n "${GIT_DIFF_ARG}" ]; then
+                set +e
+                git diff --quiet ${GIT_DIFF_ARG} -- "${d}"
+                changed=$?
+                set -e
+                if [[ "${changed}" -ne 0 ]]; then
+                    echo "change detected in ${d}"
+                    should_test=true
+                fi
             else
-                echo "change detected in ${d}"
+                # If GIT_DIFF_ARG is empty, run all the tests.
                 should_test=true
             fi
-        else
-            # If GIT_DIFF_ARG is empty, run all the tests.
-            should_test=true
-        fi
-        if [ "${should_test}" = true ]; then
-            echo "running test in ${d}"
-            pushd ${d}
-            # Temporarily allow failure.
-            set +e
-            ${test_script}
-            ret=$?
-            set -e
-            if [ ${ret} -ne 0 ]; then
-                RETVAL=${ret}
+            if [ "${should_test}" = true ]; then
+                dirs_to_test+=("${d}")
             fi
-            popd
-        fi
+        done
     done
-done
+fi
+
+if [ ${#dirs_to_test[@]} -eq 0 ]; then
+    echo "No packages to test."
+    exit 0
+fi
+
+# Run tests across target packages in parallel using available CPU cores
+NPROC=$(nproc 2>/dev/null || echo 4)
+echo "Running tests across ${#dirs_to_test[@]} package(s) using ${NPROC} parallel workers..."
 
-exit ${RETVAL}
+printf "%s\0" "${dirs_to_test[@]}" | xargs -0 -P "${NPROC}" -I {} bash -c 'run_test_in_dir "$@"' _ {}
diff --git a/packages/google-crc32c/.coveragerc b/packages/google-crc32c/.coveragerc
index 195287608806..ab4a10fdea4b 100644
--- a/packages/google-crc32c/.coveragerc
+++ b/packages/google-crc32c/.coveragerc
@@ -22,7 +22,7 @@ omit =
   google/cloud/__init__.py
 
 [report]
-fail_under = 100
+fail_under = 0
 show_missing = True
 exclude_lines =
     # Re-enable the standard pragma

From b6cbd6272a23eeb756ce0e943961887d59f32754 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 17:35:27 +0000
Subject: [PATCH 05/22] restore 3.15

---
 .github/workflows/unittest.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 196359ddf6e6..56bfce0ab3ba 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -79,7 +79,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        python: ['3.10', "3.11", "3.12", "3.13", "3.14"]
+        python: ['3.10', "3.11", "3.12", "3.13", "3.14", "3.15"]
         package_shard: ${{ fromJson(needs.initialize.outputs.matrix) }}
     name: ${{ matrix.package_shard.is_sharded && format('unit ({0}, {1})', matrix.python, matrix.package_shard.name) || format('unit ({0})', matrix.python) }}
     steps:

From 2f8483a0cfb2687b1d36cdae726b2d999811c1ef Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 17:38:28 +0000
Subject: [PATCH 06/22] restore 3.15

---
 .github/workflows/unittest.yml | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 56bfce0ab3ba..91e89d0106ab 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -96,10 +96,28 @@ jobs:
       with:
         python-version: ${{ matrix.python }}
         cache: 'pip'
+        allow-prereleases: true
+    - name: Setup uv
+      uses: astral-sh/setup-uv@v5
+      with:
+        enable-cache: true
+        cache-dependency-glob: 'packages/**/testing/constraints*.txt'
     - name: Install nox
       run: |
         python -m pip install --upgrade setuptools pip wheel
-        python -m pip install nox uv
+        python -m pip install nox
+        uv pip install --system nox nox-uv
+    # Caches compiled wheels locally to prevent building heavy libraries
+    # such as grpcio, which we build from scratch on every run for Python 3.15+.
+    # Follow https://github.com/grpc/grpc/issues/41010 for updates.
+    - name: Cache Built Python 3.15 Wheels
+      if: matrix.python == '3.15'
+      uses: actions/cache@v4
+      with:
+        path: .uv-wheel-cache
+        key: ${{ runner.os }}-uv-wheels-3.15-${{ hashFiles('packages/**/testing/constraints*.txt') }}
+        restore-keys: |
+          ${{ runner.os }}-uv-wheels-3.15-
     - name: Run unit tests for ${{ matrix.package_shard.description }}
       env:
         BUILD_TYPE: presubmit

From ea8c9a6f330261ba52920fa4a4be13cf87c76516 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 17:43:02 +0000
Subject: [PATCH 07/22] address zizmor

---
 .github/workflows/unittest.yml | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 91e89d0106ab..6c1ca82d3f55 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -43,9 +43,10 @@ jobs:
         google-shopping-merchant-accounts: 4
     steps:
     - name: Checkout
-      uses: actions/checkout@v4
+      uses: actions/checkout@11d5960a326750d5838078e36cf38b85af677262 # v4
       with:
         fetch-depth: 2
+        persist-credentials: false
     - name: Check for unit_test:all_packages label
       id: check-label
       run: |
@@ -55,7 +56,7 @@ jobs:
           echo "is_full_run=false" >> $GITHUB_OUTPUT
         fi
     - name: Setup Python
-      uses: actions/setup-python@v5
+      uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
       with:
         python-version: "3.10"
     - name: Get package shards
@@ -98,7 +99,7 @@ jobs:
         cache: 'pip'
         allow-prereleases: true
     - name: Setup uv
-      uses: astral-sh/setup-uv@v5
+      uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86 # v5
       with:
         enable-cache: true
         cache-dependency-glob: 'packages/**/testing/constraints*.txt'
@@ -112,7 +113,7 @@ jobs:
     # Follow https://github.com/grpc/grpc/issues/41010 for updates.
     - name: Cache Built Python 3.15 Wheels
       if: matrix.python == '3.15'
-      uses: actions/cache@v4
+      uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
       with:
         path: .uv-wheel-cache
         key: ${{ runner.os }}-uv-wheels-3.15-${{ hashFiles('packages/**/testing/constraints*.txt') }}

From 6eb430fede20725f222e2d0fe80f588b28429ba6 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 17:49:49 +0000
Subject: [PATCH 08/22] address feedback

---
 packages/google-cloud-bigtable/noxfile.py | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/packages/google-cloud-bigtable/noxfile.py b/packages/google-cloud-bigtable/noxfile.py
index 0ffdf5d3c1ff..f8d639a266ed 100644
--- a/packages/google-cloud-bigtable/noxfile.py
+++ b/packages/google-cloud-bigtable/noxfile.py
@@ -242,9 +242,6 @@ def unit(session, protobuf_implementation):
     if session.python == "3.15":
         session.skip("Skipping 3.15 until wheels are available for google-crc32c.")
 
-    if session.python == "3.15":
-        session.skip("Skipping 3.15 until wheels are available for google-crc32c.")
-
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )

From f394a590d216a57a1f6e14dff75692da541d956d Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 17:52:14 +0000
Subject: [PATCH 09/22] temporarily speed up feedback

---
 .github/workflows/unittest.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 6c1ca82d3f55..f86e4eae556c 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -26,7 +26,7 @@ jobs:
       matrix: ${{ steps.set-matrix.outputs.matrix }}
       is_full_run: ${{ steps.check-label.outputs.is_full_run }}
     env:
-      MAX_SHARDS: 20
+      MAX_SHARDS: 50
       # Define weights for long-running unit tests to balance shard execution time
       # Each weight is roughly 1 minute of expected execution time
       # Default for unset packages is 1

From 527dcaee5c5e14e59ae4a165c15a0c62fd929561 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 17:59:32 +0000
Subject: [PATCH 10/22] temporarily speed up feedback

---
 ci/get_package_shards.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ci/get_package_shards.py b/ci/get_package_shards.py
index 27c4ea6aa1f0..4ff1ac2283e3 100644
--- a/ci/get_package_shards.py
+++ b/ci/get_package_shards.py
@@ -163,7 +163,7 @@ def group_packages(packages_map):
 
     # Dynamically determine target weight to balance across max shards.
     max_shards = int(os.environ.get("MAX_SHARDS", 16))
-    target_weight = max(10, math.ceil(total_weight / max_shards))
+    target_weight = max(1, math.ceil(total_weight / max_shards))
 
     shards_list = []
     current_shard_items = []

From 6f01ed428ccff142b54916a2344f132c9c7905c0 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 18:05:04 +0000
Subject: [PATCH 11/22] revert

---
 packages/google-crc32c/.coveragerc | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/google-crc32c/.coveragerc b/packages/google-crc32c/.coveragerc
index ab4a10fdea4b..195287608806 100644
--- a/packages/google-crc32c/.coveragerc
+++ b/packages/google-crc32c/.coveragerc
@@ -22,7 +22,7 @@ omit =
   google/cloud/__init__.py
 
 [report]
-fail_under = 0
+fail_under = 100
 show_missing = True
 exclude_lines =
     # Re-enable the standard pragma

From 37f1f282bc3f4aea06c62ae07738a6e5a535ddc4 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 19:15:47 +0000
Subject: [PATCH 12/22] apply fix

---
 .github/workflows/unittest.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index f86e4eae556c..74862b9d4c85 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -75,7 +75,7 @@ jobs:
 
   unit:
     needs: initialize
-    if: needs.initialize.outputs.matrix != '[]' && needs.initialize.outputs.matrix != ''
+    if: ${{ needs.initialize.outputs.matrix && needs.initialize.outputs.matrix != '[]' }}
     runs-on: ubuntu-22.04
     strategy:
       fail-fast: true

From 34a67f6a3e8fd4f64e46b226e1978c6b1327ccc8 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 19:18:54 +0000
Subject: [PATCH 13/22] apply fix

---
 .github/workflows/unittest.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 74862b9d4c85..31b77cac9d3d 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -75,7 +75,7 @@ jobs:
 
   unit:
     needs: initialize
-    if: ${{ needs.initialize.outputs.matrix && needs.initialize.outputs.matrix != '[]' }}
+    if: ${{ needs.initialize.outputs.matrix && needs.initialize.outputs.matrix != '[]' && needs.initialize.outputs.matrix != '' }}
     runs-on: ubuntu-22.04
     strategy:
       fail-fast: true

From e3c23c91126a3ddd01e7f0787f0bd5d15c6a2cd6 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 19:22:32 +0000
Subject: [PATCH 14/22] Revert "apply fix"

This reverts commit 34a67f6a3e8fd4f64e46b226e1978c6b1327ccc8.
---
 .github/workflows/unittest.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 31b77cac9d3d..74862b9d4c85 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -75,7 +75,7 @@ jobs:
 
   unit:
     needs: initialize
-    if: ${{ needs.initialize.outputs.matrix && needs.initialize.outputs.matrix != '[]' && needs.initialize.outputs.matrix != '' }}
+    if: ${{ needs.initialize.outputs.matrix && needs.initialize.outputs.matrix != '[]' }}
     runs-on: ubuntu-22.04
     strategy:
       fail-fast: true

From 26a4d62783e244b11f144ae5688012e9e41dc16b Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 19:22:40 +0000
Subject: [PATCH 15/22] Revert "apply fix"

This reverts commit 37f1f282bc3f4aea06c62ae07738a6e5a535ddc4.
---
 .github/workflows/unittest.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 74862b9d4c85..f86e4eae556c 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -75,7 +75,7 @@ jobs:
 
   unit:
     needs: initialize
-    if: ${{ needs.initialize.outputs.matrix && needs.initialize.outputs.matrix != '[]' }}
+    if: needs.initialize.outputs.matrix != '[]' && needs.initialize.outputs.matrix != ''
     runs-on: ubuntu-22.04
     strategy:
       fail-fast: true

From d0607e1efbae91eb2ea6fa76507d2170b583ef47 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 19:22:57 +0000
Subject: [PATCH 16/22] reduce shards

---
 ci/get_package_shards.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ci/get_package_shards.py b/ci/get_package_shards.py
index 4ff1ac2283e3..9eda3e440fec 100644
--- a/ci/get_package_shards.py
+++ b/ci/get_package_shards.py
@@ -163,7 +163,7 @@ def group_packages(packages_map):
 
     # Dynamically determine target weight to balance across max shards.
     max_shards = int(os.environ.get("MAX_SHARDS", 16))
-    target_weight = max(1, math.ceil(total_weight / max_shards))
+    target_weight = max(4, math.ceil(total_weight / max_shards))
 
     shards_list = []
     current_shard_items = []

From bf8bd812ebbbfc0eeb6898a9ac51f78b01967f77 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 19:27:40 +0000
Subject: [PATCH 17/22] reduce shards

---
 ci/get_package_shards.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/ci/get_package_shards.py b/ci/get_package_shards.py
index 9eda3e440fec..0b1e18f2c076 100644
--- a/ci/get_package_shards.py
+++ b/ci/get_package_shards.py
@@ -163,7 +163,7 @@ def group_packages(packages_map):
 
     # Dynamically determine target weight to balance across max shards.
     max_shards = int(os.environ.get("MAX_SHARDS", 16))
-    target_weight = max(4, math.ceil(total_weight / max_shards))
+    target_weight = max(5, math.ceil(total_weight / max_shards))
 
     shards_list = []
     current_shard_items = []

From dcb2ad186d33176ad0fa2f3cd05cbee86e4f54fc Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 19:32:40 +0000
Subject: [PATCH 18/22] reduce shards

---
 .github/workflows/unittest.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index f86e4eae556c..6c1ca82d3f55 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -26,7 +26,7 @@ jobs:
       matrix: ${{ steps.set-matrix.outputs.matrix }}
       is_full_run: ${{ steps.check-label.outputs.is_full_run }}
     env:
-      MAX_SHARDS: 50
+      MAX_SHARDS: 20
       # Define weights for long-running unit tests to balance shard execution time
       # Each weight is roughly 1 minute of expected execution time
       # Default for unset packages is 1

From 9e6652125033afce28048bc78a966b8646bd1007 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 21:26:54 +0000
Subject: [PATCH 19/22] cache grpcio

---
 .github/workflows/unittest.yml | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 6c1ca82d3f55..ef483921ec09 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -119,6 +119,13 @@ jobs:
         key: ${{ runner.os }}-uv-wheels-3.15-${{ hashFiles('packages/**/testing/constraints*.txt') }}
         restore-keys: |
           ${{ runner.os }}-uv-wheels-3.15-
+    # Pre-cache heavy dependencies sequentially before running parallel tests
+    - name: Pre-cache heavy dependencies (grpcio)
+      if: matrix.python == '3.15'
+      run: |
+        # Download and compile grpcio sequentially so that parallel test workers
+        # immediately hit the warm cache instead of deadlocking on compilation.
+        uv pip install --system grpcio --find-links .uv-wheel-cache
     - name: Run unit tests for ${{ matrix.package_shard.description }}
       env:
         BUILD_TYPE: presubmit

From e0f000391648b1cd51362d06a86431de7b9a3f1a Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Thu, 30 Jul 2026 21:33:29 +0000
Subject: [PATCH 20/22] apply fix

---
 .github/workflows/unittest.yml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index ef483921ec09..7fff19dfadf6 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -123,6 +123,8 @@ jobs:
     - name: Pre-cache heavy dependencies (grpcio)
       if: matrix.python == '3.15'
       run: |
+        # Create the directory so uv doesn't crash if there is a `cache miss`
+        mkdir -p .uv-wheel-cache
         # Download and compile grpcio sequentially so that parallel test workers
         # immediately hit the warm cache instead of deadlocking on compilation.
         uv pip install --system grpcio --find-links .uv-wheel-cache

From 3f89358d9172c14d9742b897e98190e6c276e449 Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Fri, 31 Jul 2026 14:54:27 +0000
Subject: [PATCH 21/22] revert

---
 .github/workflows/lint.yml     | 78 +++++++++++++++++++++++++++++-----
 .github/workflows/unittest.yml | 55 ++++++++----------------
 ci/get_package_shards.py       | 12 +++---
 ci/run_conditional_tests.sh    | 77 ++++++++++++++-------------------
 4 files changed, 125 insertions(+), 97 deletions(-)

diff --git a/.github/workflows/lint.yml b/.github/workflows/lint.yml
index e7fb1fec6a0c..69402439d08a 100644
--- a/.github/workflows/lint.yml
+++ b/.github/workflows/lint.yml
@@ -17,8 +17,50 @@ env:
   NOX_ENVDIR: "/tmp/shared_nox_envs"
   NOX_DEFAULT_VENV_BACKEND: "uv"
   UV_VENV_SEED: "1"
+  # Run checks in parallel using 4 cores
+  PARALLEL_WORKERS: "4"
 
 jobs:
+  initialize:
+    runs-on: ubuntu-latest
+    outputs:
+      matrix: ${{ steps.set-matrix.outputs.matrix }}
+      is_full_run: ${{ steps.check-label.outputs.is_full_run }}
+    env:
+      MAX_SHARDS: 4
+    steps:
+    - name: Checkout
+      uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
+      # Use a fetch-depth of 2 to avoid error `fatal: origin/main...HEAD: no merge base`
+      # See https://github.com/googleapis/google-cloud-python/issues/12013
+      # and https://github.com/actions/checkout#checkout-head.
+      with:
+        fetch-depth: 2
+        persist-credentials: false
+    - name: Check for unit_test:all_packages label
+      id: check-label
+      run: |
+        if [[ "${{ contains(github.event.pull_request.labels.*.name, 'unit_test:all_packages') }}" == "true" ]]; then
+          echo "is_full_run=true" >> $GITHUB_OUTPUT
+        else
+          echo "is_full_run=false" >> $GITHUB_OUTPUT
+        fi
+    - name: Setup Python
+      uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6
+      with:
+        python-version: "3.10"
+    - name: Get package shards
+      id: set-matrix
+      env:
+        BUILD_TYPE: presubmit
+        TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
+        TEST_ALL_PACKAGES: ${{ steps.check-label.outputs.is_full_run }}
+      run: |
+        if [ -n "$TARGET_BRANCH" ]; then
+          git fetch origin "$TARGET_BRANCH" --depth=1 || true
+        fi
+        python3 ci/get_package_shards.py
+
   lint:
     runs-on: ubuntu-latest
     steps:
@@ -66,8 +108,16 @@ jobs:
         PY_VERSION: "unused"
       run: |
         ci/run_conditional_tests.sh
-  mypy:
+
+  mypy-shard:
+    needs: initialize
+    if: needs.initialize.outputs.matrix != '[]' && needs.initialize.outputs.matrix != ''
     runs-on: ubuntu-latest
+    strategy:
+      fail-fast: true
+      matrix:
+        package_shard: ${{ fromJson(needs.initialize.outputs.matrix) }}
+    name: ${{ matrix.package_shard.is_sharded && format('mypy ({0})', matrix.package_shard.name) || format('mypy ({0})', matrix.package_shard.description) }}
     steps:
     - name: Checkout
       uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6.0.3
@@ -77,14 +127,6 @@ jobs:
       with:
         fetch-depth: 2
         persist-credentials: false
-    - name: Check for unit_test:all_packages label
-      id: check-label
-      run: |
-        if [[ "${{ contains(github.event.pull_request.labels.*.name, 'unit_test:all_packages') }}" == "true" ]]; then
-          echo "is_full_run=true" >> $GITHUB_OUTPUT
-        else
-          echo "is_full_run=false" >> $GITHUB_OUTPUT
-        fi
     - name: Setup Python
       uses: actions/setup-python@ece7cb06caefa5fff74198d8649806c4678c61a1 # v6
       with:
@@ -93,13 +135,27 @@ jobs:
       run: |
         python -m pip install --upgrade setuptools pip wheel
         python -m pip install nox uv
-    - name: Run mypy
+    - name: Run mypy for ${{ matrix.package_shard.description }}
       env:
         BUILD_TYPE: presubmit
         TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
-        TEST_ALL_PACKAGES: ${{ steps.check-label.outputs.is_full_run }}
         TEST_TYPE: mypy
+        PACKAGE_LIST: ${{ matrix.package_shard.packages }}
         # TODO(https://github.com/googleapis/google-cloud-python/issues/13775): Specify `PY_VERSION` rather than relying on the default python version of the nox session.
         PY_VERSION: "unused"
       run: |
         ci/run_conditional_tests.sh
+
+  mypy-status:
+    if: always()
+    needs: [initialize, mypy-shard]
+    runs-on: ubuntu-latest
+    name: mypy-status
+    steps:
+    - name: Check mypy job status
+      run: |
+        if [[ "${{ needs['mypy-shard'].result }}" != "success" && "${{ needs['mypy-shard'].result }}" != "skipped" ]]; then
+          echo "mypy failed with result: ${{ needs['mypy-shard'].result }}"
+          exit 1
+        fi
+        echo "All mypy shards passed successfully!"
diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index 7fff19dfadf6..c9e8f5239bf1 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -18,6 +18,9 @@ env:
   NOX_ENVDIR: "/tmp/shared_nox_envs"
   NOX_DEFAULT_VENV_BACKEND: "uv"
   UV_VENV_SEED: "1"
+  # Note: PARALLEL_WORKERS must remain "1" for unit tests because running pytest concurrently
+  # on the same runner VM can cause socket/IPC/process deadlocks across packages.
+  PARALLEL_WORKERS: "1"
 
 jobs:
   initialize:
@@ -26,7 +29,7 @@ jobs:
       matrix: ${{ steps.set-matrix.outputs.matrix }}
       is_full_run: ${{ steps.check-label.outputs.is_full_run }}
     env:
-      MAX_SHARDS: 20
+      MAX_SHARDS: 16
       # Define weights for long-running unit tests to balance shard execution time
       # Each weight is roughly 1 minute of expected execution time
       # Default for unset packages is 1
@@ -80,7 +83,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        python: ['3.10', "3.11", "3.12", "3.13", "3.14", "3.15"]
+        python: ['3.10', "3.11", "3.12", "3.13", "3.14"]
         package_shard: ${{ fromJson(needs.initialize.outputs.matrix) }}
     name: ${{ matrix.package_shard.is_sharded && format('unit ({0}, {1})', matrix.python, matrix.package_shard.name) || format('unit ({0})', matrix.python) }}
     steps:
@@ -97,37 +100,10 @@ jobs:
       with:
         python-version: ${{ matrix.python }}
         cache: 'pip'
-        allow-prereleases: true
-    - name: Setup uv
-      uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86 # v5
-      with:
-        enable-cache: true
-        cache-dependency-glob: 'packages/**/testing/constraints*.txt'
     - name: Install nox
       run: |
         python -m pip install --upgrade setuptools pip wheel
-        python -m pip install nox
-        uv pip install --system nox nox-uv
-    # Caches compiled wheels locally to prevent building heavy libraries
-    # such as grpcio, which we build from scratch on every run for Python 3.15+.
-    # Follow https://github.com/grpc/grpc/issues/41010 for updates.
-    - name: Cache Built Python 3.15 Wheels
-      if: matrix.python == '3.15'
-      uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
-      with:
-        path: .uv-wheel-cache
-        key: ${{ runner.os }}-uv-wheels-3.15-${{ hashFiles('packages/**/testing/constraints*.txt') }}
-        restore-keys: |
-          ${{ runner.os }}-uv-wheels-3.15-
-    # Pre-cache heavy dependencies sequentially before running parallel tests
-    - name: Pre-cache heavy dependencies (grpcio)
-      if: matrix.python == '3.15'
-      run: |
-        # Create the directory so uv doesn't crash if there is a `cache miss`
-        mkdir -p .uv-wheel-cache
-        # Download and compile grpcio sequentially so that parallel test workers
-        # immediately hit the warm cache instead of deadlocking on compilation.
-        uv pip install --system grpcio --find-links .uv-wheel-cache
+        python -m pip install nox uv
     - name: Run unit tests for ${{ matrix.package_shard.description }}
       env:
         BUILD_TYPE: presubmit
@@ -164,9 +140,10 @@ jobs:
           echo "All unit tests passed or were skipped"
 
   cover:
+    if: always() && !cancelled() && needs.all-tests.result == 'success'
     runs-on: ubuntu-latest
     needs:
-        - unit
+        - all-tests
         - initialize
     steps:
     - name: Checkout
@@ -181,33 +158,37 @@ jobs:
       uses: actions/setup-python@a26af69be951a213d495a4c3e4e4022e16d87065 # v5
       with:
         python-version: "3.10"
-    - name: Set number of files changes in packages and preview-packages directories
+    - name: Determine if coverage evaluation is required
       id: packages
       env:
         TEST_ALL_PACKAGES: ${{ needs.initialize.outputs.is_full_run }}
         TARGET_BRANCH: ${{ github.base_ref || github.event.merge_group.base_ref }}
       run: |
         if [[ "${TEST_ALL_PACKAGES}" == "true" ]]; then
-          echo "num_files_changed=1" >> "$GITHUB_OUTPUT"
+          echo "should_evaluate_coverage=true" >> "$GITHUB_OUTPUT"
         else
           TARGET_BRANCH="${TARGET_BRANCH:-main}"
           git fetch origin "$TARGET_BRANCH" --depth=1 || true
           num_files_changed=$(git diff --name-only "origin/${TARGET_BRANCH}" -- ${PACKAGE_DIRS} | wc -l | tr -d ' ')
-          echo "num_files_changed=${num_files_changed}" >> "$GITHUB_OUTPUT"
+          if [[ "${num_files_changed}" -gt 0 ]]; then
+            echo "should_evaluate_coverage=true" >> "$GITHUB_OUTPUT"
+          else
+            echo "should_evaluate_coverage=false" >> "$GITHUB_OUTPUT"
+          fi
         fi
     - name: Install coverage
-      if: ${{ steps.packages.outputs.num_files_changed > 0 }}
+      if: ${{ steps.packages.outputs.should_evaluate_coverage == 'true' }}
       run: |
         python -m pip install --upgrade setuptools pip wheel
         python -m pip install coverage
     - name: Download coverage results
-      if: ${{ steps.packages.outputs.num_files_changed > 0 }}
+      if: ${{ steps.packages.outputs.should_evaluate_coverage == 'true' }}
       uses: actions/download-artifact@634f93cb2916e3fdff6788551b99b062d0335ce0 # v5
       with:
         path: /dev/shm/.coverage-results/
         merge-multiple: true
     - name: Report coverage results
-      if: ${{ steps.packages.outputs.num_files_changed > 0 }}
+      if: ${{ steps.packages.outputs.should_evaluate_coverage == 'true' }}
       env:
         # TODO: default to 100% coverage after next gapic-generator release
         # https://github.com/googleapis/google-cloud-python/issues/17459
diff --git a/ci/get_package_shards.py b/ci/get_package_shards.py
index 0b1e18f2c076..77cc191cc3ac 100644
--- a/ci/get_package_shards.py
+++ b/ci/get_package_shards.py
@@ -122,15 +122,17 @@ def get_packages_to_test():
         return all_packages
 
     package_dirs = set(get_package_directories())
-    to_test_names = set()
+    to_test_paths = collections.defaultdict(list)
     for f in changed_files:
         parts = f.split('/')
         if len(parts) >= 2 and parts[0] in package_dirs:
             pkg_name = parts[1]
-            if pkg_name in all_packages:
-                to_test_names.add(pkg_name)
+            full_path = f"{parts[0]}/{parts[1]}/"
+            if pkg_name in all_packages and full_path in all_packages[pkg_name]:
+                if full_path not in to_test_paths[pkg_name]:
+                    to_test_paths[pkg_name].append(full_path)
 
-    return {name: all_packages[name] for name in to_test_names}
+    return dict(to_test_paths)
 
 
 def group_packages(packages_map):
@@ -163,7 +165,7 @@ def group_packages(packages_map):
 
     # Dynamically determine target weight to balance across max shards.
     max_shards = int(os.environ.get("MAX_SHARDS", 16))
-    target_weight = max(5, math.ceil(total_weight / max_shards))
+    target_weight = max(10, math.ceil(total_weight / max_shards))
 
     shards_list = []
     current_shard_items = []
diff --git a/ci/run_conditional_tests.sh b/ci/run_conditional_tests.sh
index 9901711aee1a..241de51a4f88 100755
--- a/ci/run_conditional_tests.sh
+++ b/ci/run_conditional_tests.sh
@@ -47,10 +47,27 @@ git config --global url."${PROJECT_ROOT}".insteadOf "https://github.com/googleap
 # A script file for running the test in a sub project.
 test_script="${PROJECT_ROOT}/ci/run_single_test.sh"
 
-# Global exit code tracker
-RETVAL=0
+if [ "${TEST_ALL_PACKAGES}" = "true" ]; then
+    GIT_DIFF_ARG=""
+
+elif [[ ${BUILD_TYPE} == "presubmit" ]]; then
+    # For presubmit build, we want to know the difference from the
+    # common commit in the target branch.
+    if [ -n "${TARGET_BRANCH}" ]; then
+        git fetch origin "${TARGET_BRANCH}" --depth=1 || true
+    fi
+    GIT_DIFF_ARG="origin/${TARGET_BRANCH}"
+
+elif [[ ${BUILD_TYPE} == "continuous" ]]; then
+    # For continuous build, we want to know the difference in the last
+    # commit. This assumes we use squash commit when merging PRs.
+    GIT_DIFF_ARG="HEAD~1.."
+
+else
+    # Run everything.
+    GIT_DIFF_ARG=""
+fi
 
-# Shared test execution logic
 run_test_in_dir() {
     local d=$1
     local pkg_name_clean=$(echo ${d} | sed 's|/$||' | sed 's|/|_|g')
@@ -58,29 +75,22 @@ run_test_in_dir() {
     export COVERAGE_FILE="${PROJECT_ROOT}/.coverage.${PY_VERSION}.${pkg_name_clean}"
 
     pushd ${d} > /dev/null
-
-    # Temporarily allow failure.
     set +e
     ${test_script} > "${log_file}" 2>&1
     local ret=$?
     set -e
-
     popd > /dev/null
 
-    # Atomically print complete package log block so parallel outputs never interleave
-    {
-        echo "============================================================"
-        echo "Running tests in ${d}"
-        echo "============================================================"
-        cat "${log_file}"
-        rm -f "${log_file}"
-    }
+    echo "============================================================"
+    echo "Running tests in ${d}"
+    echo "============================================================"
+    cat "${log_file}"
+    rm -f "${log_file}"
 
     if [ ${ret} -ne 0 ]; then
         exit ${ret}
     fi
 }
-
 export -f run_test_in_dir
 export test_script PROJECT_ROOT PY_VERSION TEST_TYPE
 
@@ -88,31 +98,8 @@ dirs_to_test=()
 
 if [ -n "${PACKAGE_LIST}" ]; then
     echo "Using provided PACKAGE_LIST"
-    for d in ${PACKAGE_LIST}; do
-        dirs_to_test+=("${d}")
-    done
+    dirs_to_test=(${PACKAGE_LIST})
 else
-    if [ "${TEST_ALL_PACKAGES}" = "true" ]; then
-        GIT_DIFF_ARG=""
-
-    elif [[ ${BUILD_TYPE} == "presubmit" ]]; then
-        # For presubmit build, we want to know the difference from the target branch.
-        TARGET_BRANCH="${TARGET_BRANCH:-main}"
-        if [ -n "${TARGET_BRANCH}" ]; then
-            git fetch origin "${TARGET_BRANCH}" --depth=1 || true
-        fi
-        GIT_DIFF_ARG="origin/${TARGET_BRANCH}"
-
-    elif [[ ${BUILD_TYPE} == "continuous" ]]; then
-        # For continuous build, we want to know the difference in the last
-        # commit. This assumes we use squash commit when merging PRs.
-        GIT_DIFF_ARG="HEAD~1.."
-
-    else
-        # Run everything.
-        GIT_DIFF_ARG=""
-    fi
-
     subdirs=(${PACKAGE_DIRS:-packages preview-packages})
 
     for subdir in ${subdirs[@]}; do
@@ -125,7 +112,6 @@ else
                 changed=$?
                 set -e
                 if [[ "${changed}" -ne 0 ]]; then
-                    echo "change detected in ${d}"
                     should_test=true
                 fi
             else
@@ -144,8 +130,11 @@ if [ ${#dirs_to_test[@]} -eq 0 ]; then
     exit 0
 fi
 
-# Run tests across target packages in parallel using available CPU cores
-NPROC=$(nproc 2>/dev/null || echo 4)
-echo "Running tests across ${#dirs_to_test[@]} package(s) using ${NPROC} parallel workers..."
+PARALLEL_WORKERS="${PARALLEL_WORKERS:-1}"
+AVAIL_CORES=$(nproc 2>/dev/null || echo 4)
+if [ "${PARALLEL_WORKERS}" -gt "${AVAIL_CORES}" ]; then
+    PARALLEL_WORKERS="${AVAIL_CORES}"
+fi
 
-printf "%s\0" "${dirs_to_test[@]}" | xargs -0 -P "${NPROC}" -I {} bash -c 'run_test_in_dir "$@"' _ {}
+echo "Running tests across ${#dirs_to_test[@]} package(s) using ${PARALLEL_WORKERS} parallel worker(s)..."
+printf "%s\0" "${dirs_to_test[@]}" | xargs -0 -P "${PARALLEL_WORKERS}" -I {} bash -c 'run_test_in_dir "$@"' _ {}

From f1d158fac83f3cb907092c6e79e3b4934992cebd Mon Sep 17 00:00:00 2001
From: Anthonios Partheniou <partheniou@google.com>
Date: Fri, 31 Jul 2026 14:56:25 +0000
Subject: [PATCH 22/22] Restore

---
 .github/workflows/unittest.yml | 32 ++++++++++++++++++++++++++++++--
 1 file changed, 30 insertions(+), 2 deletions(-)

diff --git a/.github/workflows/unittest.yml b/.github/workflows/unittest.yml
index c9e8f5239bf1..bf08d7832869 100644
--- a/.github/workflows/unittest.yml
+++ b/.github/workflows/unittest.yml
@@ -83,7 +83,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        python: ['3.10', "3.11", "3.12", "3.13", "3.14"]
+        python: ["3.10", "3.11", "3.12", "3.13", "3.14", "3.15"]
         package_shard: ${{ fromJson(needs.initialize.outputs.matrix) }}
     name: ${{ matrix.package_shard.is_sharded && format('unit ({0}, {1})', matrix.python, matrix.package_shard.name) || format('unit ({0})', matrix.python) }}
     steps:
@@ -100,10 +100,38 @@ jobs:
       with:
         python-version: ${{ matrix.python }}
         cache: 'pip'
+        allow-prereleases: true
+    - name: Setup uv
+      uses: astral-sh/setup-uv@d4b2f3b6ecc6e67c4457f6d3e41ec42d3d0fcb86 # v5
+      with:
+        enable-cache: true
+        cache-dependency-glob: 'packages/**/testing/constraints*.txt'
     - name: Install nox
       run: |
         python -m pip install --upgrade setuptools pip wheel
-        python -m pip install nox uv
+        python -m pip install nox
+    - name: Run unit tests
+        uv pip install --system nox nox-uv
+    # Caches compiled wheels locally to prevent building heavy libraries
+    # such as grpcio, which we build from scratch on every run for Python 3.15+.
+    # Follow https://github.com/grpc/grpc/issues/41010 for updates.
+    - name: Cache Built Python 3.15 Wheels
+      if: matrix.python == '3.15'
+      uses: actions/cache@0057852bfaa89a56745cba8c7296529d2fc39830 # v4
+      with:
+        path: .uv-wheel-cache
+        key: ${{ runner.os }}-uv-wheels-3.15-${{ hashFiles('packages/**/testing/constraints*.txt') }}
+        restore-keys: |
+          ${{ runner.os }}-uv-wheels-3.15-
+    # Pre-cache heavy dependencies sequentially before running parallel tests
+    - name: Pre-cache heavy dependencies (grpcio)
+      if: matrix.python == '3.15'
+      run: |
+        # Create the directory so uv doesn't crash if there is a `cache miss`
+        mkdir -p .uv-wheel-cache
+        # Download and compile grpcio sequentially so that parallel test workers
+        # immediately hit the warm cache instead of deadlocking on compilation.
+        uv pip install --system grpcio --find-links .uv-wheel-cache
     - name: Run unit tests for ${{ matrix.package_shard.description }}
       env:
         BUILD_TYPE: presubmit