diff --git a/.github/workflows/_pr-test-rust-ext-build.yml b/.github/workflows/_pr-test-rust-ext-build.yml
new file mode 100644
index 000000000..5d832d947
--- /dev/null
+++ b/.github/workflows/_pr-test-rust-ext-build.yml
@@ -0,0 +1,188 @@
+name: PR Test - Build Rust Extensions
+
+# Builds the rust/ workspace's PyO3 extension modules once so the CUDA test
+# stages install with SGLANG_BUILD_RUST_EXTS=none instead of each rebuilding them.
+#
+# Why: uv holds the editable sdist lock in the shared ~/.cache/uv for the whole
+# build, cargo included, so CUDA jobs on one host serialize on it - and once the
+# Rust build passed a few minutes, the queue's tail hit uv's lock timeout.
+#
+# The win is compiling once per run instead of in all ~25 install steps; the two
+# layers below only decide who pays for it.
+# - The cache, keyed by a source hash, carries a build across runs - no version to
+#   bump, unlike sgl-kernel, which publishes one because it ships to users.
+# - The artifact hands it to the stages, which the cache cannot: it is best-effort,
+#   evictable, and this repo is at its 10 GB limit. Artifacts are durable per run.
+#
+# Two jobs, because only compiling needs the build node: exactly one runner carries
+# that label and it also serves the sgl-kernel and docker builds, so queueing there
+# on a cache hit would put its wait in front of every stage. Republishing bytes
+# needs no particular host - the glibc a module requires is recorded in the module,
+# not decided by whoever uploads it.
+
+on:
+  workflow_call:
+    inputs:
+      runs_on:
+        description: 'Runner label for the compile job. Must be self-hosted: its glibc has to satisfy max_glibc, and the cargo build cache needs a persistent ~/.cache.'
+        type: string
+        required: true
+      restore_runs_on:
+        description: 'Runner label for the cache-hit path. Wants free capacity and nothing else, since it neither compiles nor imports the modules.'
+        type: string
+        default: ubuntu-latest
+      artifact_name:
+        description: 'Artifact name. Suffix it per caller: artifacts are immutable per name per run, so two callers sharing a run would collide.'
+        type: string
+        default: rust-ext-x86_64
+      cache_key_prefix:
+        description: 'Cache key prefix. Callers share it on purpose to reuse each other''s build; it encodes the arch, since the modules are not portable across architectures.'
+        type: string
+        default: rust-ext-x86_64
+      max_glibc:
+        description: 'Highest GLIBC symbol version the built .so files may require. Set by the oldest test runner image, jammy at glibc 2.35 - the pools are not all on one image.'
+        type: string
+        default: '2.35'
+      git_ref:
+        type: string
+        default: ''
+      skip_pr_test_health_check:
+        description: 'Forwarded from the caller for the check-maintenance action.'
+        type: boolean
+        default: false
+    outputs:
+      artifact_name:
+        description: 'Artifact holding the built modules. Empty when neither job published one, whether skipped or failed; consumers that still run compile them during install.'
+        value: ${{ jobs.restore.outputs.artifact_name || jobs.compile.outputs.artifact_name }}
+
+# Reusable workflows do not inherit the caller's env; mirror what
+# check-maintenance reads.
+env:
+  SGLANG_IS_IN_CI: true
+  SKIP_PR_TEST_HEALTH_CHECK: ${{ inputs.skip_pr_test_health_check && 'true' || 'false' }}
+  PR_TEST_BYPASS_MAINTENANCE_ON_MAIN: ${{ github.ref == 'refs/heads/main' && 'true' || 'false' }}
+
+jobs:
+  restore:
+    runs-on: ${{ inputs.restore_runs_on }}
+    timeout-minutes: 15
+    name: Restore Rust Ext
+    outputs:
+      hit: ${{ steps.cache.outputs.cache-hit }}
+      # From the last step, so a failed job publishes no name for always() consumers.
+      artifact_name: ${{ steps.publish.outputs.name }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ inputs.git_ref || github.sha }}
+          # Just what the cache key hashes, plus the action and script this job
+          # runs: the workspace is cold here and the rest of the tree is mostly
+          # docs. Both jobs must hash the same rust/** set, which this preserves.
+          # Cone mode off is what allows naming a single file.
+          sparse-checkout: |
+            rust
+            python/setup.py
+            .github
+            scripts/ci/utils
+          sparse-checkout-cone-mode: false
+
+      - uses: ./.github/actions/check-maintenance
+
+      # setup.py counts because it selects which crates get built. pyproject.toml
+      # is left out - it churns on bumps that cannot affect these modules.
+      - name: Restore built modules
+        id: cache
+        uses: actions/cache/restore@v4
+        with:
+          path: python/sglang/srt/*/_core*.so
+          key: ${{ inputs.cache_key_prefix }}-${{ hashFiles('rust/**', 'python/setup.py') }}
+
+      # No MAX_GLIBC: these are the bytes the compile job already checked before
+      # saving them under this key. The module count is still worth re-checking,
+      # so a truncated entry fails here rather than as a test import error.
+      - name: Stage modules for upload
+        if: steps.cache.outputs.cache-hit == 'true'
+        run: bash scripts/ci/utils/stage_rust_ext_modules.sh
+
+      - name: Upload extension modules
+        if: steps.cache.outputs.cache-hit == 'true'
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ inputs.artifact_name }}
+          # Archive holds <pkg>/_core*.so, so it unpacks into python/sglang/srt/.
+          path: rust-ext-staging/
+          if-no-files-found: error
+          retention-days: 1
+
+      - name: Publish artifact name
+        id: publish
+        if: steps.cache.outputs.cache-hit == 'true'
+        run: echo "name=${{ inputs.artifact_name }}" >> "$GITHUB_OUTPUT"
+
+  compile:
+    needs: restore
+    if: needs.restore.outputs.hit != 'true'
+    runs-on: ${{ inputs.runs_on }}
+    timeout-minutes: 60
+    name: Build Rust Ext
+    outputs:
+      artifact_name: ${{ steps.publish.outputs.name }}
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          ref: ${{ inputs.git_ref || github.sha }}
+
+      - uses: ./.github/actions/check-maintenance
+
+      # No crate sets abi3, so the ABI tag is minor-version specific and only the
+      # pools on this version can use the result - h20 ships 3.12 and falls back to
+      # compiling during install. Pinned rather than left to the image so the tag is
+      # at least predictable.
+      - name: Set up Python 3.10
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.10'
+
+      - name: Install protoc and Rust toolchain
+        run: bash scripts/ci/utils/install_rust_protoc.sh
+
+      - name: Build extension modules
+        run: |
+          set -euxo pipefail
+          export PATH="${CARGO_HOME:-$HOME/.cargo}/bin:${PATH}"
+          # Same path ci_install_dependency.sh uses: one warm cargo cache per host.
+          export CARGO_TARGET_DIR="${HOME}/.cache/sglang-cargo-target"
+          python3 -m pip install --upgrade pip
+          command -v uv >/dev/null 2>&1 || pip install uv
+          # build_rust needs only the build backend, not sglang's ~294 runtime deps.
+          uv venv /tmp/rust-ext-build --python python3.10 --seed
+          # shellcheck disable=SC1091
+          source /tmp/rust-ext-build/bin/activate
+          uv pip install "setuptools>=61.0" "setuptools-rust>=1.10" "setuptools-scm>=8.0" wheel
+          cd python
+          SGLANG_BUILD_RUST_EXTS=all python setup.py build_rust --inplace
+
+      - name: Verify modules and stage for upload
+        env:
+          MAX_GLIBC: ${{ inputs.max_glibc }}
+        run: bash scripts/ci/utils/stage_rust_ext_modules.sh
+
+      # After the verify step, so a rejected build cannot poison this key for every
+      # later run.
+      - name: Save built modules
+        uses: actions/cache/save@v4
+        with:
+          path: python/sglang/srt/*/_core*.so
+          key: ${{ inputs.cache_key_prefix }}-${{ hashFiles('rust/**', 'python/setup.py') }}
+
+      - name: Upload extension modules
+        uses: actions/upload-artifact@v4
+        with:
+          name: ${{ inputs.artifact_name }}
+          path: rust-ext-staging/
+          if-no-files-found: error
+          retention-days: 1
+
+      - name: Publish artifact name
+        id: publish
+        run: echo "name=${{ inputs.artifact_name }}" >> "$GITHUB_OUTPUT"
diff --git a/.github/workflows/_pr-test-stage.yml b/.github/workflows/_pr-test-stage.yml
index 3dd77c072..f0861b30c 100644
--- a/.github/workflows/_pr-test-stage.yml
+++ b/.github/workflows/_pr-test-stage.yml
@@ -54,6 +54,10 @@ on:
         description: 'pytest path to run after the suite (b200 FA4 jit_kernel tests). Empty skips.'
         type: string
         default: ''
+      rust_ext_artifact:
+        description: 'Artifact of prebuilt Rust extension modules, from rust-ext-build. Empty, or a download that fails, means this stage compiles them during install.'
+        type: string
+        default: ''
 
 # Mirror pr-test.yml top-level env. Reusable workflows do NOT inherit caller's
 # workflow-level env across the workflow_call boundary, so anything pr-test.yml
@@ -120,10 +124,23 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda*
 
+      # continue-on-error: the artifact expires in a day, so a later re-run just
+      # compiles during install. download-artifact creates srt/server/, which
+      # exists only as build output.
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: ${{ fromJson(steps.rc.outputs.install_timeout) }}
         env:
           GRACE_BLACKWELL: ${{ steps.rc.outputs.grace_blackwell || '0' }}
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{ fromJson(inputs.check_changes).sgl_kernel }} bash ${{ steps.rc.outputs.install }}
 
diff --git a/.github/workflows/pr-test-extra.yml b/.github/workflows/pr-test-extra.yml
index c004b923c..944d1f236 100644
--- a/.github/workflows/pr-test-extra.yml
+++ b/.github/workflows/pr-test-extra.yml
@@ -131,9 +131,28 @@ jobs:
       skip_pr_test_health_check: ${{ inputs.skip_pr_test_health_check == true }}
     secrets: inherit
 
+  # =============================================== Rust extensions ====================================================
+
+  # Own build job because artifacts are per-run: a standalone `run-ci-extra` run
+  # cannot reach the base run's. Only artifact_name is suffixed; the cache prefix
+  # stays at the default so the two workflows share one cache entry.
+  rust-ext-build:
+    needs: [check-changes, call-gate]
+    if: |
+      !cancelled() &&
+      needs.check-changes.result == 'success' &&
+      (needs.call-gate.result == 'success' || needs.call-gate.result == 'skipped')
+    uses: ./.github/workflows/_pr-test-rust-ext-build.yml
+    with:
+      runs_on: x64-kernel-build-node
+      artifact_name: rust-ext-x86_64-extra
+      git_ref: ${{ inputs.git_ref || '' }}
+      skip_pr_test_health_check: ${{ inputs.skip_pr_test_health_check == true }}
+    secrets: inherit
+
   # =============================================== extra-a (1-/2-gpu) ===============================================
   extra-a-test-1-gpu-small:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() && needs.check-changes.result == 'success' && (needs.call-gate.result == 'success' || needs.call-gate.result == 'skipped') }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -143,10 +162,11 @@ jobs:
       caller_inputs: ${{ toJson(inputs) }}
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '60'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   extra-a-test-1-gpu-large:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() && needs.check-changes.result == 'success' && (needs.call-gate.result == 'success' || needs.call-gate.result == 'skipped') }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -157,10 +177,11 @@ jobs:
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '60'
       timeout_per_file: '1800'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   extra-a-test-2-gpu-large:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() && needs.check-changes.result == 'success' && (needs.call-gate.result == 'success' || needs.call-gate.result == 'skipped') }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -170,11 +191,12 @@ jobs:
       caller_inputs: ${{ toJson(inputs) }}
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '60'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   # =============================================== extra-b (4-/8-gpu) ===============================================
   extra-b-test-4-gpu-h100:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() && needs.check-changes.result == 'success' && (needs.call-gate.result == 'success' || needs.call-gate.result == 'skipped') }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -184,10 +206,11 @@ jobs:
       caller_inputs: ${{ toJson(inputs) }}
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '60'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   extra-b-test-4-gpu-b200:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() && needs.check-changes.result == 'success' && (needs.call-gate.result == 'success' || needs.call-gate.result == 'skipped') }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -198,10 +221,11 @@ jobs:
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '60'
       timeout_per_file: '1800'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   extra-b-test-8-gpu-h200:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() && needs.check-changes.result == 'success' && (needs.call-gate.result == 'success' || needs.call-gate.result == 'skipped') }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -211,10 +235,11 @@ jobs:
       caller_inputs: ${{ toJson(inputs) }}
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '60'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   extra-b-test-deepep-4-gpu-h100:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() && needs.check-changes.result == 'success' && (needs.call-gate.result == 'success' || needs.call-gate.result == 'skipped') }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -224,10 +249,11 @@ jobs:
       caller_inputs: ${{ toJson(inputs) }}
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '60'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   extra-b-test-deepep-4-gpu-b200:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() && needs.check-changes.result == 'success' && (needs.call-gate.result == 'success' || needs.call-gate.result == 'skipped') }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -238,10 +264,11 @@ jobs:
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '60'
       timeout_per_file: '1800'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   extra-b-test-deepep-8-gpu-h200:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() && needs.check-changes.result == 'success' && (needs.call-gate.result == 'success' || needs.call-gate.result == 'skipped') }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -251,6 +278,7 @@ jobs:
       caller_inputs: ${{ toJson(inputs) }}
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '60'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   # =============================================== aggregator ====================================================
@@ -263,6 +291,7 @@ jobs:
         check-changes,
         call-gate,
         sgl-kernel-build-wheels,
+        rust-ext-build,
         extra-a-test-1-gpu-small,
         extra-a-test-1-gpu-large,
         extra-a-test-2-gpu-large,
diff --git a/.github/workflows/pr-test-jit-kernel.yml b/.github/workflows/pr-test-jit-kernel.yml
index 3c91479b9..5d8c59316 100644
--- a/.github/workflows/pr-test-jit-kernel.yml
+++ b/.github/workflows/pr-test-jit-kernel.yml
@@ -9,6 +9,10 @@ on:
       sgl_kernel:
         required: true
         type: string
+      rust_ext_artifact:
+        description: 'Artifact of prebuilt Rust extension modules, from rust-ext-build. Empty, or a download that fails, means this job compiles them during install.'
+        type: string
+        default: ''
       runner_config:
         required: true
         type: string
@@ -67,8 +71,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda13.0
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{ inputs.sgl_kernel }} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
 
@@ -105,8 +120,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda13.0
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{ inputs.sgl_kernel }} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
 
@@ -145,8 +171,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda13.0
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{ inputs.sgl_kernel }} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
 
@@ -185,8 +222,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda13.0
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{ inputs.sgl_kernel }} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
 
diff --git a/.github/workflows/pr-test-multimodal-gen.yml b/.github/workflows/pr-test-multimodal-gen.yml
index c91356a30..eea4b4ba3 100644
--- a/.github/workflows/pr-test-multimodal-gen.yml
+++ b/.github/workflows/pr-test-multimodal-gen.yml
@@ -9,6 +9,10 @@ on:
       sgl_kernel:
         required: true
         type: string
+      rust_ext_artifact:
+        description: 'Artifact of prebuilt Rust extension modules, from rust-ext-build. Empty, or a download that fails, means this job compiles them during install.'
+        type: string
+        default: ''
       runner_config:
         required: true
         type: string
@@ -102,8 +106,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda*
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{inputs.sgl_kernel}} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
       - name: Run diffusion server tests
@@ -168,8 +183,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda*
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{inputs.sgl_kernel}} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
 
@@ -231,8 +257,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda*
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{inputs.sgl_kernel}} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
 
@@ -293,8 +330,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda*
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{inputs.sgl_kernel}} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
 
@@ -362,8 +410,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda*
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{inputs.sgl_kernel}} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
 
@@ -407,10 +466,20 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda*
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
         env:
           SGLANG_CI_EARLY_LD_LIBRARY_PATH: "1"
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{inputs.sgl_kernel}} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
 
@@ -461,8 +530,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda*
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{inputs.sgl_kernel}} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
 
diff --git a/.github/workflows/pr-test-sgl-kernel.yml b/.github/workflows/pr-test-sgl-kernel.yml
index dd0ccd7d1..8c3872716 100644
--- a/.github/workflows/pr-test-sgl-kernel.yml
+++ b/.github/workflows/pr-test-sgl-kernel.yml
@@ -6,6 +6,10 @@ on:
       sgl_kernel:
         required: true
         type: string
+      rust_ext_artifact:
+        description: 'Artifact of prebuilt Rust extension modules, from rust-ext-build. Empty, or a download that fails, means this job compiles them during install.'
+        type: string
+        default: ''
       runner_config:
         required: true
         type: string
@@ -54,8 +58,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda*
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{inputs.sgl_kernel}} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
 
@@ -89,8 +104,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda*
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{inputs.sgl_kernel}} bash scripts/ci/cuda/ci_install_dependency.sh
 
@@ -136,8 +162,19 @@ jobs:
           merge-multiple: true
           pattern: wheel-python3.10-cuda*
 
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ inputs.rust_ext_artifact != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ inputs.rust_ext_artifact }}
+          path: python/sglang/srt/
+
       - name: Install dependencies
         timeout-minutes: 20
+        env:
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           CUSTOM_BUILD_SGL_KERNEL=${{inputs.sgl_kernel}} bash scripts/ci/cuda/ci_install_dependency.sh diffusion
 
diff --git a/.github/workflows/pr-test.yml b/.github/workflows/pr-test.yml
index 65a8b8d42..ab7bf10b6 100644
--- a/.github/workflows/pr-test.yml
+++ b/.github/workflows/pr-test.yml
@@ -208,8 +208,31 @@ jobs:
       skip_pr_test_health_check: ${{ inputs.skip_pr_test_health_check == true }}
     secrets: inherit
 
+  # =============================================== Rust extensions ====================================================
+
+  # Unlike sgl-kernel, not gated on source changes: the cache key is the source
+  # hash, so the job always runs but only compiles on a miss.
+  rust-ext-build:
+    needs: [check-changes, call-gate]
+    # Ungated on the event, unlike the jobs above: a cache entry is visible to
+    # every PR only if it was written from the default branch's ref, so every
+    # main-ref run - schedule, dispatch, workflow_call - has to seed it.
+    #
+    # !cancelled() so a skipped call-gate does not take this job with it, since a
+    # docs-only PR still installs sglang in every stage.
+    if: |
+      !cancelled() &&
+      needs.check-changes.result == 'success' &&
+      (needs.call-gate.result == 'success' || needs.call-gate.result == 'skipped')
+    uses: ./.github/workflows/_pr-test-rust-ext-build.yml
+    with:
+      runs_on: x64-kernel-build-node
+      git_ref: ${{ inputs.git_ref || '' }}
+      skip_pr_test_health_check: ${{ inputs.skip_pr_test_health_check == true }}
+    secrets: inherit
+
   call-sgl-kernel-tests:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     if: |
       github.event_name != 'schedule' &&
       inputs.test_parallel_dispatch != true &&
@@ -221,12 +244,13 @@ jobs:
       sgl_kernel: ${{ needs.check-changes.outputs.sgl_kernel }}
       git_ref: ${{ inputs.git_ref || '' }}
       skip_pr_test_health_check: ${{ inputs.skip_pr_test_health_check == true }}
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   # =============================================== jit-kernel ====================================================
 
   call-jit-kernel-tests:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     # Run on scheduled/parallel-dispatch runs (same pattern as the base-* stages) so the
     # jit_kernel suite is exercised on main 3x daily, not only on PRs that touch kernels/**.
     # check-changes already forces jit_kernel='true' on scheduled runs (run_all_tests).
@@ -246,13 +270,14 @@ jobs:
       git_ref: ${{ inputs.git_ref || '' }}
       test_parallel_dispatch: ${{ inputs.test_parallel_dispatch == true && 'true' || 'false' }}
       skip_pr_test_health_check: ${{ inputs.skip_pr_test_health_check == true }}
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   # =============================================== primary ====================================================
 
   # Runs on 5090 (32GB, SM120)
   base-a-test-1-gpu-small:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -262,10 +287,11 @@ jobs:
       caller_inputs: ${{ toJson(inputs) }}
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '10'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   base-a-test-cpu:
-    needs: [check-changes, call-gate]
+    needs: [check-changes, call-gate, rust-ext-build]
     if: |
       always() &&
       needs.check-changes.result == 'success' &&
@@ -303,13 +329,29 @@ jobs:
       - name: Install uv
         uses: astral-sh/setup-uv@v5
 
-      # Needed by setuptools-rust to build the bundled native gRPC extension
-      # (rust/sglang-grpc) when installing the main `sglang` wheel from source.
+      # This stage compiled the workspace too - 7+ minutes per partition on
+      # billable hosted minutes. rust-ext-build's modules need an older glibc than
+      # this runner has, which is the safe direction, and both pin Python 3.10.
+      - name: Download prebuilt Rust extensions
+        id: rust_ext
+        if: ${{ needs.rust-ext-build.outputs.artifact_name != '' }}
+        continue-on-error: true
+        uses: actions/download-artifact@v4
+        with:
+          name: ${{ needs.rust-ext-build.outputs.artifact_name }}
+          path: python/sglang/srt/
+
+      # Both only serve the fallback where this stage compiles the extensions
+      # itself, so they follow the download's outcome, not the job output: an
+      # expired artifact still needs cargo and a warm target dir here. Otherwise
+      # rust-cache restores ~1 GB per partition for nothing, on an over-quota cache.
       - name: Install protoc + Rust toolchain
+        if: ${{ steps.rust_ext.outcome != 'success' }}
         timeout-minutes: 10
         run: bash scripts/ci/utils/install_rust_protoc.sh
 
       - name: Rust cache (rust/ workspace)
+        if: ${{ steps.rust_ext.outcome != 'success' }}
         uses: Swatinem/rust-cache@v2
         with:
           workspaces: rust
@@ -321,6 +363,7 @@ jobs:
         timeout-minutes: 20
         env:
           UV_SYSTEM_PYTHON: "1"
+          SGLANG_BUILD_RUST_EXTS: ${{ steps.rust_ext.outcome == 'success' && 'none' || '' }}
         run: |
           uv pip install -e "python[dev]" --index-strategy unsafe-best-match --prerelease allow
 
@@ -357,7 +400,7 @@ jobs:
 
   # Runs on 5090 (32GB, SM120)
   base-b-test-1-gpu-small:
-    needs: [check-changes, call-gate, wait-for-base-a, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, wait-for-base-a, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -367,11 +410,12 @@ jobs:
       caller_inputs: ${{ toJson(inputs) }}
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '30'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   # Runs on H100 (80GB, SM90) - tests that don't pass on 5090 (FA3, FP8, high VRAM, etc.)
   base-b-test-1-gpu-large:
-    needs: [check-changes, call-gate, wait-for-base-a, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, wait-for-base-a, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -382,10 +426,11 @@ jobs:
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '30'
       timeout_per_file: '1800'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   base-b-test-2-gpu-large:
-    needs: [check-changes, call-gate, wait-for-base-a, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, wait-for-base-a, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -395,10 +440,11 @@ jobs:
       caller_inputs: ${{ toJson(inputs) }}
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '30'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   base-b-test-4-gpu-b200:
-    needs: [check-changes, call-gate, wait-for-base-a, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, wait-for-base-a, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -408,10 +454,11 @@ jobs:
       caller_inputs: ${{ toJson(inputs) }}
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '40'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   call-multimodal-gen-tests:
-    needs: [check-changes, call-gate, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, sgl-kernel-build-wheels, rust-ext-build]
     if: |
       always() &&
       !cancelled() &&
@@ -428,10 +475,11 @@ jobs:
       test_parallel_dispatch: ${{ inputs.test_parallel_dispatch == true && 'true' || 'false' }}
       caller_needs_failure: ${{ (needs.call-gate.result == 'failure' || needs.sgl-kernel-build-wheels.result == 'failure' || needs.check-changes.result == 'failure') && 'true' || 'false' }}
       skip_pr_test_health_check: ${{ inputs.skip_pr_test_health_check == true && 'true' || 'false' }}
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   base-c-test-4-gpu-h100:
-    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -441,10 +489,11 @@ jobs:
       caller_inputs: ${{ toJson(inputs) }}
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '30'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   base-c-test-8-gpu-h200:
-    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -461,10 +510,11 @@ jobs:
       # Server CUDA Graph warmup is combined into this step (warmup_server_models unset).
       warmup_deep_gemm_models: 'deepseek-ai/DeepSeek-V3-0324:8 deepseek-ai/DeepSeek-V3.2:8 zai-org/GLM-5-FP8:8 XiaomiMiMo/MiMo-V2-Flash:4 XiaomiMiMo/MiMo-V2.5:8'
       warmup_timeout_minutes: '60'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   base-c-test-8-gpu-h20:
-    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -474,10 +524,11 @@ jobs:
       caller_inputs: ${{ toJson(inputs) }}
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '30'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   base-c-test-deepep-4-gpu-h100:
-    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -489,10 +540,11 @@ jobs:
       run_timeout_minutes: '30'
       warmup_deep_gemm_models: 'lmsys/sglang-ci-dsv3-test:4'
       warmup_server_models: 'lmsys/sglang-ci-dsv3-test:4'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   base-c-test-deepep-4-gpu-b200:
-    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -503,10 +555,11 @@ jobs:
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '30'
       timeout_per_file: '1800'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   base-c-test-deepep-8-gpu-h200:
-    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -517,10 +570,11 @@ jobs:
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '30'
       timeout_per_file: '1800'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   base-c-test-4-gpu-b200:
-    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -531,10 +585,11 @@ jobs:
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '30'
       timeout_per_file: '1800'
+      rust_ext_artifact: ${{ needs.rust-ext-build.outputs.artifact_name }}
     secrets: inherit
 
   base-c-test-4-gpu-gb300:
-    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels]
+    needs: [check-changes, call-gate, wait-for-base-b, sgl-kernel-build-wheels, rust-ext-build]
     if: ${{ !failure() && !cancelled() }}
     uses: ./.github/workflows/_pr-test-stage.yml
     with:
@@ -545,8 +600,13 @@ jobs:
       partitions: ${{ needs.check-changes.outputs.partitions }}
       run_timeout_minutes: '30'
       timeout_per_file: '1800'
+      # aarch64 has no prebuild, so this stage compiles during install - which also
+      # makes it the only stage still covering that path. Keep it that way.
+      rust_ext_artifact: ''
     secrets: inherit
 
+  # List every build and test job: `skipped` passes here, so an omission turns that
+  # job's failure into a green run with no tests.
   pr-test-finish:
     needs:
       [
@@ -557,6 +617,8 @@ jobs:
         sgl-kernel-build-wheels-arm,
         call-sgl-kernel-tests,
 
+        rust-ext-build,
+
         wait-for-base-a,
         wait-for-base-b,
 
diff --git a/scripts/ci/cuda/ci_install_dependency.sh b/scripts/ci/cuda/ci_install_dependency.sh
index fa08dd3fa..4d02d1d3d 100755
--- a/scripts/ci/cuda/ci_install_dependency.sh
+++ b/scripts/ci/cuda/ci_install_dependency.sh
@@ -326,6 +326,40 @@ uninstall_stale_flashinfer() {
     mark_step_done "${FUNCNAME[0]}"
 }
 
+require_prebuilt_rust_exts() {
+    # Stages whose download succeeded set this to none. Runs before
+    # setup_pip_toolchain uninstalls sglang, so clearing it here still reaches
+    # install_sglang below - setup.py reads it from the environment at build time.
+    if [ "${SGLANG_BUILD_RUST_EXTS:-}" != "none" ]; then
+        mark_step_done "${FUNCNAME[0]}"
+        return
+    fi
+
+    # Exact EXT_SUFFIX rather than a _core*.so glob: no crate sets abi3, so a module
+    # built for another minor version satisfies the glob while the import system
+    # ignores it, leaving is_rust_server_built() false and the Rust-server tests
+    # silently skipped. Stages have no setup-python, so the interpreter is whatever
+    # the image ships, and the pools are not on one version (h20 is 3.12 while
+    # h100 is 3.10) - a mismatch is drift to route around, not a failure.
+    local suffix
+    suffix=$(python3 -c 'import sysconfig; print(sysconfig.get_config_var("EXT_SUFFIX"))')
+    local missing=()
+    local pkg
+    for pkg in server grpc multimodal; do
+        [ -f "python/sglang/srt/${pkg}/_core${suffix}" ] || missing+=("${pkg}")
+    done
+    if [ ${#missing[@]} -gt 0 ]; then
+        echo "::warning::no prebuilt _core${suffix} for: ${missing[*]}; building from source"
+        ls -l python/sglang/srt/*/_core*.so 2>/dev/null || echo "(no extension modules at all)"
+        export SGLANG_BUILD_RUST_EXTS=
+        mark_step_done "${FUNCNAME[0]}"
+        return
+    fi
+    echo "Using prebuilt Rust extension modules; skipping the cargo build."
+
+    mark_step_done "${FUNCNAME[0]}"
+}
+
 install_sglang() {
     EXTRAS="dev,runai,tracing"
     if [ -n "$OPTIONAL_DEPS" ]; then
@@ -654,6 +688,7 @@ main() {
     install_apt_packages
     clean_site_packages
     setup_cargo_cache
+    require_prebuilt_rust_exts
     setup_pip_toolchain
     remove_stale_cuda12_nvidia_wheels
     uninstall_stale_flashinfer
diff --git a/scripts/ci/utils/stage_rust_ext_modules.sh b/scripts/ci/utils/stage_rust_ext_modules.sh
new file mode 100755
index 000000000..27b64bf54
--- /dev/null
+++ b/scripts/ci/utils/stage_rust_ext_modules.sh
@@ -0,0 +1,43 @@
+#!/bin/bash
+# Copy the built PyO3 extension modules into rust-ext-staging/<pkg>/ for
+# upload-artifact. Shared by both jobs of _pr-test-rust-ext-build.yml, so the
+# archive layout and the module-count check cannot drift between them.
+#
+# MAX_GLIBC (optional): also reject a module requiring a newer GLIBC symbol
+# version than the test runners have. Only set where the modules were just
+# compiled - on a cache hit these are the same bytes that already passed.
+set -euo pipefail
+shopt -s nullglob
+# upload-artifact strips the longest common prefix it matched, so a missing
+# module would silently shift the archive layout.
+rm -rf rust-ext-staging
+built=()
+for pkg in server grpc multimodal; do
+    found=(python/sglang/srt/"${pkg}"/_core*.so)
+    if [ ${#found[@]} -ne 1 ]; then
+        echo "::error::expected exactly one extension module for ${pkg}, found ${#found[@]}"
+        exit 1
+    fi
+    mkdir -p "rust-ext-staging/${pkg}"
+    cp "${found[0]}" "rust-ext-staging/${pkg}/"
+    built+=("${found[0]}")
+done
+max_allowed="${MAX_GLIBC:-}"
+[ -n "${max_allowed}" ] || exit 0
+
+# Newer glibc than the test runners fails at import: "GLIBC_2.xx not found".
+status=0
+for so in "${built[@]}"; do
+    # grep exits 1 with no match; without `|| true` pipefail kills the script.
+    needed=$(objdump -T "$so" \
+        | grep -oE 'GLIBC_2\.[0-9]+' \
+        | sed 's/GLIBC_//' \
+        | sort -V | tail -1 || true)
+    echo "${so}: requires glibc <= ${needed:-none}"
+    if [ -n "${needed}" ] \
+       && [ "$(printf '%s\n%s\n' "${max_allowed}" "${needed}" | sort -V | tail -1)" != "${max_allowed}" ]; then
+        echo "::error::${so} requires glibc ${needed} > ${max_allowed} supported by the test runners; build on an older image"
+        status=1
+    fi
+done
+exit $status