diff --git a/.github/workflows/gpu_l4_golden_parity.yml b/.github/workflows/gpu_l4_golden_parity.yml
index 5e74b7fb2..bae580e1b 100644
--- a/.github/workflows/gpu_l4_golden_parity.yml
+++ b/.github/workflows/gpu_l4_golden_parity.yml
@@ -74,8 +74,9 @@ jobs:
         run: |
           pip install -r requirements/ci/requirements.txt
           pip install soundfile librosa ml_dtypes flatbuffers numpy packaging protobuf sympy coloredlogs
-          pip install -e '.[testing,transformers]'
+          pip install -e '.[testing,transformers]' -r requirements/ci/transformers.txt
           pip install --force-reinstall --no-deps -r requirements/ci/vibevoice.txt
+          python -c "from transformers import AutoConfig"
           # PyPI's ORT 1.27+ wheel requires CUDA 13, while these runners use CUDA 12.
           pip install --pre --no-deps --index-url https://aiinfra.pkgs.visualstudio.com/PublicPackages/_packaging/onnxruntime-cuda-12/pypi/simple/ onnxruntime-gpu
           pip install --no-deps onnxruntime-genai-cuda
diff --git a/.github/workflows/gpu_l5_generation_e2e.yml b/.github/workflows/gpu_l5_generation_e2e.yml
index 0c377f75d..3c5b957d2 100644
--- a/.github/workflows/gpu_l5_generation_e2e.yml
+++ b/.github/workflows/gpu_l5_generation_e2e.yml
@@ -74,8 +74,9 @@ jobs:
         run: |
           pip install -r requirements/ci/requirements.txt
           pip install soundfile librosa ml_dtypes flatbuffers numpy packaging protobuf sympy coloredlogs
-          pip install -e '.[testing,transformers]'
+          pip install -e '.[testing,transformers]' -r requirements/ci/transformers.txt
           pip install --force-reinstall --no-deps -r requirements/ci/vibevoice.txt
+          python -c "from transformers import AutoConfig"
           # PyPI's ORT 1.27+ wheel requires CUDA 13, while these runners use CUDA 12.
           pip install --pre --no-deps --index-url https://aiinfra.pkgs.visualstudio.com/PublicPackages/_packaging/onnxruntime-cuda-12/pypi/simple/ onnxruntime-gpu
           pip install --no-deps onnxruntime-genai-cuda
diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index a04d16ed4..950fc48cf 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -148,8 +148,9 @@ jobs:
         run: |
           pip install -r requirements/ci/requirements.txt
           pip install onnxruntime
-          pip install -e '.[testing,transformers]'
+          pip install -e '.[testing,transformers]' -r requirements/ci/transformers.txt
           pip install --force-reinstall --no-deps -r requirements/ci/vibevoice.txt
+          python -c "from transformers import AutoConfig"
       - name: Run L3 synthetic parity tests
         env:
           HF_TOKEN: ${{ secrets.HF_TOKEN }}
@@ -257,8 +258,9 @@ jobs:
         run: |
           pip install -r requirements/ci/requirements.txt
           pip install onnxruntime
-          pip install -e '.[testing]'
+          pip install -e '.[testing]' -r requirements/ci/transformers.txt
           pip install --force-reinstall --no-deps -r requirements/ci/vibevoice.txt
+          python -c "from transformers import AutoConfig"
       - name: Run tests
         run: |
           pytest -n auto -m 'not integration and not arch_validation' --cov=src --cov-report=xml --cov-branch --junitxml junit.xml
diff --git a/.github/workflows/nightly_l2.yml b/.github/workflows/nightly_l2.yml
index 55899f71a..31aaa27b9 100644
--- a/.github/workflows/nightly_l2.yml
+++ b/.github/workflows/nightly_l2.yml
@@ -51,8 +51,9 @@ jobs:
       - name: Install dependencies
         run: |
           pip install -r requirements/ci/requirements.txt
-          pip install -e '.[testing]'
+          pip install -e '.[testing]' -r requirements/ci/transformers.txt
           pip install --force-reinstall --no-deps -r requirements/ci/vibevoice.txt
+          python -c "from transformers import AutoConfig"
 
       # Run sequentially (-p no:xdist) to stay under 2GB RAM
       - name: Run L2 architecture validation tests
diff --git a/requirements/ci/transformers.txt b/requirements/ci/transformers.txt
new file mode 100644
index 000000000..5eed633b9
--- /dev/null
+++ b/requirements/ci/transformers.txt
@@ -0,0 +1,3 @@
+# VibeVoice support requires this source revision. Resolve its dependencies
+# together with the project before installing VibeVoice with --no-deps.
+transformers @ git+https://github.com/huggingface/transformers.git@640a08a597034221ca1c4fc0c129cf0118179225
diff --git a/requirements/ci/vibevoice.txt b/requirements/ci/vibevoice.txt
index 541e8026d..74e822a99 100644
--- a/requirements/ci/vibevoice.txt
+++ b/requirements/ci/vibevoice.txt
@@ -1,5 +1,5 @@
-# VibeVoice is upstream but not yet available in a released Transformers wheel.
-transformers @ git+https://github.com/huggingface/transformers.git@640a08a597034221ca1c4fc0c129cf0118179225
 # Exact source used by VibeVoice Realtime L3 synthetic parity tests. CI installs
-# this file with --no-deps, retaining the test environment's Transformers build.
+# this file with --no-deps after resolving requirements/ci/transformers.txt.
+# Upstream still declares Transformers <5; the CI reference uses the pinned
+# Transformers source above rather than downgrading to that older API.
 vibevoice @ git+https://github.com/microsoft/VibeVoice.git@79e516a3e20b599f137c9da03410a2a0b473b63b