diff --git a/.github/workflows/perf.yml b/.github/workflows/perf.yml
index 9e5c321..c97e0a0 100644
--- a/.github/workflows/perf.yml
+++ b/.github/workflows/perf.yml
@@ -51,9 +51,23 @@ jobs:
           node-version: "20"
           cache: npm
 
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
       - name: Install npm dependencies
         run: npm ci
 
+      - name: Build Sigima wheel
+        run: |
+          python -m pip install "$(grep '^Babel' requirements-dev.txt)"
+          python scripts/build_sigima_wheel.py \
+            "$(grep '^sigima @ ' requirements-dev.txt)" .wheels
+          wheel_path=$(find "$GITHUB_WORKSPACE/.wheels" -name 'sigima-*.whl' -print -quit)
+          test -n "$wheel_path"
+          echo "VITE_SIGIMA_INSTALL_SPEC=/@fs/$wheel_path" >> "$GITHUB_ENV"
+
       - name: Install Playwright browser
         run: npx playwright install --with-deps chromium
 
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index d789a55..cfcde9c 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -77,9 +77,22 @@ jobs:
           node-version: 20
           cache: npm
 
+      - uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
       - name: Install npm dependencies
         run: npm ci
 
+      - name: Build Sigima wheel
+        run: |
+          python -m pip install "$(grep '^Babel' requirements-dev.txt)"
+          python scripts/build_sigima_wheel.py \
+            "$(grep '^sigima @ ' requirements-dev.txt)" .wheels
+          wheel_path=$(find "$GITHUB_WORKSPACE/.wheels" -name 'sigima-*.whl' -print -quit)
+          test -n "$wheel_path"
+          echo "VITE_SIGIMA_INSTALL_SPEC=/@fs/$wheel_path" >> "$GITHUB_ENV"
+
       - name: Install Playwright browsers
         run: npx playwright install --with-deps chromium
 
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 6f1d94e..b11a44c 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -93,9 +93,23 @@ jobs:
           node-version: "20"
           cache: npm
 
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: "3.12"
+
       - name: Install npm dependencies
         run: npm ci
 
+      - name: Build Sigima wheel
+        run: |
+          python -m pip install "$(grep '^Babel' requirements-dev.txt)"
+          python scripts/build_sigima_wheel.py \
+            "$(grep '^sigima @ ' requirements-dev.txt)" .wheels
+          wheel_path=$(find "$GITHUB_WORKSPACE/.wheels" -name 'sigima-*.whl' -print -quit)
+          test -n "$wheel_path"
+          echo "VITE_SIGIMA_INSTALL_SPEC=/@fs/$wheel_path" >> "$GITHUB_ENV"
+
       - name: Install Playwright browsers
         run: npx playwright install --with-deps chromium
 
diff --git a/requirements-dev.txt b/requirements-dev.txt
index c320e39..109e43f 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -9,6 +9,7 @@
 # Core test runner and coverage tooling.
 pytest>=7.4
 pytest-cov>=4.1
+Babel>=2.17
 
 # Linters / formatters used by the VS Code tasks (Ruff + Pylint).
 ruff>=0.5
@@ -19,8 +20,8 @@ pylint>=3.0
 pre-commit>=3.7
 
 # Sigima (= computation engine) and its mandatory dependencies.
-# Pinning floors only — exact versions come from each project's pyproject.
-sigima>=1.3.0
+# Pin the unreleased revision that provides the annotation APIs used here.
+sigima @ https://github.com/DataLab-Platform/Sigima/archive/4442ada873655f63fabd14369fd11170f75a28b4.zip
 guidata>=3.15.0
 numpy>=1.22
 scipy>=1.10.1
diff --git a/scripts/build_sigima_wheel.py b/scripts/build_sigima_wheel.py
new file mode 100644
index 0000000..ec9b191
--- /dev/null
+++ b/scripts/build_sigima_wheel.py
@@ -0,0 +1,84 @@
+# Copyright (c) DataLab Platform Developers, BSD 3-Clause license, see LICENSE file.
+
+"""Build a Sigima source requirement with compiled gettext catalogs."""
+
+from __future__ import annotations
+
+import argparse
+import shutil
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+
+
+def run(*args: str) -> None:
+    """Run a Python module command with the active interpreter."""
+    subprocess.run([sys.executable, *args], check=True)
+
+
+def build_wheel(requirement: str, wheel_dir: Path) -> Path:
+    """Build *requirement* into *wheel_dir* after compiling translations."""
+    wheel_dir.mkdir(parents=True, exist_ok=True)
+    with tempfile.TemporaryDirectory(prefix="sigima-wheel-") as tmp:
+        workspace = Path(tmp)
+        downloads = workspace / "downloads"
+        downloads.mkdir()
+        run(
+            "-m",
+            "pip",
+            "download",
+            "--no-deps",
+            "--no-binary=:all:",
+            "--dest",
+            str(downloads),
+            requirement,
+        )
+
+        archives = list(downloads.iterdir())
+        if len(archives) != 1:
+            raise RuntimeError(f"Expected one Sigima archive, found {len(archives)}")
+        source_tree = workspace / "source"
+        shutil.unpack_archive(archives[0], source_tree)
+
+        projects = list(source_tree.glob("*/pyproject.toml"))
+        if len(projects) != 1:
+            raise RuntimeError(f"Expected one Sigima project, found {len(projects)}")
+        project = projects[0].parent
+        locale_dir = project / "sigima" / "locale"
+        run(
+            "-m",
+            "babel.messages.frontend",
+            "compile",
+            "--directory",
+            str(locale_dir),
+            "--domain",
+            "sigima",
+        )
+        run(
+            "-m",
+            "pip",
+            "wheel",
+            "--no-deps",
+            "--wheel-dir",
+            str(wheel_dir),
+            str(project),
+        )
+
+    wheels = list(wheel_dir.glob("sigima-*.whl"))
+    if len(wheels) != 1:
+        raise RuntimeError(f"Expected one Sigima wheel, found {len(wheels)}")
+    return wheels[0]
+
+
+def main() -> None:
+    """Build a wheel from the requested Sigima source revision."""
+    parser = argparse.ArgumentParser(description=__doc__)
+    parser.add_argument("requirement", help="PEP 508 Sigima source requirement")
+    parser.add_argument("wheel_dir", type=Path, help="Output wheel directory")
+    args = parser.parse_args()
+    print(build_wheel(args.requirement, args.wheel_dir))
+
+
+if __name__ == "__main__":
+    main()