diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index fba8992..6da4c99 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -51,6 +51,34 @@ jobs:
       - run: cargo fmt --check
       - run: cargo clippy --all-targets -- -D warnings
 
+  integrity:
+    name: Workspace Integrity
+    # Catches workspace structure / feature-gate drift early.
+    # Canonical artifact: ~/lightarchitects/soul/helix/user/standards/workspace-integrity-ci.yml
+    runs-on: ubuntu-latest
+    timeout-minutes: 10
+    steps:
+      - uses: actions/checkout@v4
+      - uses: dtolnay/rust-toolchain@stable
+      - uses: Swatinem/rust-cache@v2
+
+      - name: Configure SOUL git credentials
+        if: env.NEEDS_SOUL == 'true'
+        env:
+          SOUL_TOKEN: ${{ secrets.SOUL_GIT_TOKEN }}
+        run: |
+          git config --global credential.helper store
+          echo "https://gitlab-ci-token:${SOUL_TOKEN}@gitlab.com" > ~/.git-credentials
+
+      - name: cargo metadata (workspace declaration parseable)
+        run: cargo metadata --format-version 1 --no-deps > /dev/null
+
+      - name: cargo build --workspace --no-default-features
+        run: cargo build --workspace --no-default-features
+
+      - name: cargo build --workspace --all-features
+        run: cargo build --workspace --all-features
+
   test:
     name: Tests
     runs-on: macos-latest