diff --git a/.github/scripts/rusty_v8_bazel.py b/.github/scripts/rusty_v8_bazel.py
index 712c2e3004..f2712d4a31 100644
--- a/.github/scripts/rusty_v8_bazel.py
+++ b/.github/scripts/rusty_v8_bazel.py
@@ -29,6 +29,8 @@ MUSL_RUNTIME_ARCHIVE_LABELS = [
 ]
 LLVM_AR_LABEL = "@llvm//tools:llvm-ar"
 LLVM_RANLIB_LABEL = "@llvm//tools:llvm-ranlib"
+RELEASE_ARTIFACT_PROFILE = "release"
+SANDBOX_ARTIFACT_PROFILE = "ptrcomp_sandbox_release"
 
 
 def bazel_execroot() -> Path:
@@ -126,9 +128,10 @@ def ensure_bazel_output_files(
     return outputs
 
 
-def release_pair_label(target: str) -> str:
+def release_pair_label(target: str, sandbox: bool = False) -> str:
     target_suffix = target.replace("-", "_")
-    return f"//third_party/v8:rusty_v8_release_pair_{target_suffix}"
+    pair_kind = "sandbox_release_pair" if sandbox else "release_pair"
+    return f"//third_party/v8:rusty_v8_{pair_kind}_{target_suffix}"
 
 
 def resolved_v8_crate_version() -> str:
@@ -180,10 +183,18 @@ def command_manifest_path(manifest: Path | None, version: str) -> Path:
     return ROOT / manifest
 
 
-def staged_archive_name(target: str, source_path: Path) -> str:
+def staged_archive_name(target: str, source_path: Path, artifact_profile: str) -> str:
     if source_path.suffix == ".lib":
-        return f"rusty_v8_release_{target}.lib.gz"
-    return f"librusty_v8_release_{target}.a.gz"
+        return f"rusty_v8_{artifact_profile}_{target}.lib.gz"
+    return f"librusty_v8_{artifact_profile}_{target}.a.gz"
+
+
+def staged_binding_name(target: str, artifact_profile: str) -> str:
+    return f"src_binding_{artifact_profile}_{target}.rs"
+
+
+def staged_checksums_name(target: str, artifact_profile: str) -> str:
+    return f"rusty_v8_{artifact_profile}_{target}.sha256"
 
 
 def is_musl_archive_target(target: str, source_path: Path) -> bool:
@@ -285,10 +296,11 @@ def stage_release_pair(
     output_dir: Path,
     compilation_mode: str = "fastbuild",
     bazel_configs: list[str] | None = None,
+    sandbox: bool = False,
 ) -> None:
     outputs = ensure_bazel_output_files(
         platform,
-        [release_pair_label(target)],
+        [release_pair_label(target, sandbox)],
         compilation_mode,
         bazel_configs,
     )
@@ -304,8 +316,9 @@ def stage_release_pair(
         raise SystemExit(f"missing Rust binding output for {target}") from exc
 
     output_dir.mkdir(parents=True, exist_ok=True)
-    staged_library = output_dir / staged_archive_name(target, lib_path)
-    staged_binding = output_dir / f"src_binding_release_{target}.rs"
+    artifact_profile = SANDBOX_ARTIFACT_PROFILE if sandbox else RELEASE_ARTIFACT_PROFILE
+    staged_library = output_dir / staged_archive_name(target, lib_path, artifact_profile)
+    staged_binding = output_dir / staged_binding_name(target, artifact_profile)
     source_archive = (
         merged_musl_archive(platform, lib_path, compilation_mode, bazel_configs)
         if is_musl_archive_target(target, lib_path)
@@ -324,7 +337,7 @@ def stage_release_pair(
 
     shutil.copyfile(binding_path, staged_binding)
 
-    staged_checksums = output_dir / f"rusty_v8_release_{target}.sha256"
+    staged_checksums = output_dir / staged_checksums_name(target, artifact_profile)
     with staged_checksums.open("w", encoding="utf-8") as checksums:
         for path in [staged_library, staged_binding]:
             digest = hashlib.sha256()
@@ -346,6 +359,7 @@ def parse_args() -> argparse.Namespace:
     stage_release_pair_parser.add_argument("--platform", required=True)
     stage_release_pair_parser.add_argument("--target", required=True)
     stage_release_pair_parser.add_argument("--output-dir", required=True)
+    stage_release_pair_parser.add_argument("--sandbox", action="store_true")
     stage_release_pair_parser.add_argument(
         "--bazel-config",
         action="append",
@@ -390,6 +404,7 @@ def main() -> int:
             output_dir=Path(args.output_dir),
             compilation_mode=args.compilation_mode,
             bazel_configs=args.bazel_configs,
+            sandbox=args.sandbox,
         )
         return 0
     if args.command == "resolved-v8-crate-version":
diff --git a/.github/scripts/test_rusty_v8_bazel.py b/.github/scripts/test_rusty_v8_bazel.py
index 95c3eac157..c013eb7ca8 100644
--- a/.github/scripts/test_rusty_v8_bazel.py
+++ b/.github/scripts/test_rusty_v8_bazel.py
@@ -13,6 +13,46 @@ import rusty_v8_module_bazel
 
 
 class RustyV8BazelTest(unittest.TestCase):
+    def test_release_pair_labels_and_staged_names_distinguish_sandbox_artifacts(self) -> None:
+        self.assertEqual(
+            "//third_party/v8:rusty_v8_release_pair_x86_64_unknown_linux_musl",
+            rusty_v8_bazel.release_pair_label("x86_64-unknown-linux-musl"),
+        )
+        self.assertEqual(
+            "//third_party/v8:rusty_v8_sandbox_release_pair_x86_64_unknown_linux_musl",
+            rusty_v8_bazel.release_pair_label("x86_64-unknown-linux-musl", sandbox=True),
+        )
+        self.assertEqual(
+            "librusty_v8_release_x86_64-unknown-linux-musl.a.gz",
+            rusty_v8_bazel.staged_archive_name(
+                "x86_64-unknown-linux-musl",
+                Path("libv8.a"),
+                rusty_v8_bazel.RELEASE_ARTIFACT_PROFILE,
+            ),
+        )
+        self.assertEqual(
+            "rusty_v8_ptrcomp_sandbox_release_x86_64-pc-windows-msvc.lib.gz",
+            rusty_v8_bazel.staged_archive_name(
+                "x86_64-pc-windows-msvc",
+                Path("v8.lib"),
+                rusty_v8_bazel.SANDBOX_ARTIFACT_PROFILE,
+            ),
+        )
+        self.assertEqual(
+            "src_binding_ptrcomp_sandbox_release_x86_64-unknown-linux-musl.rs",
+            rusty_v8_bazel.staged_binding_name(
+                "x86_64-unknown-linux-musl",
+                rusty_v8_bazel.SANDBOX_ARTIFACT_PROFILE,
+            ),
+        )
+        self.assertEqual(
+            "rusty_v8_ptrcomp_sandbox_release_x86_64-unknown-linux-musl.sha256",
+            rusty_v8_bazel.staged_checksums_name(
+                "x86_64-unknown-linux-musl",
+                rusty_v8_bazel.SANDBOX_ARTIFACT_PROFILE,
+            ),
+        )
+
     @patch("rusty_v8_bazel.ensure_bazel_output_files")
     @patch("rusty_v8_bazel.subprocess.run")
     def test_host_runnable_bazel_output_file_selects_runnable_candidate(
diff --git a/.github/workflows/rusty-v8-release.yml b/.github/workflows/rusty-v8-release.yml
index 5a436722bb..2b59628885 100644
--- a/.github/workflows/rusty-v8-release.yml
+++ b/.github/workflows/rusty-v8-release.yml
@@ -46,14 +46,14 @@ jobs:
           expected_release_tag="rusty-v8-v${V8_VERSION}"
           release_tag="${GITHUB_REF_NAME}"
           if [[ "${release_tag}" != "${expected_release_tag}" ]]; then
-            echo "Tag ${release_tag} does not match resolved v8 crate version ${V8_VERSION}." >&2
+            echo "Tag ${release_tag} does not match expected release tag ${expected_release_tag}." >&2
             exit 1
           fi
 
           echo "release_tag=${release_tag}" >> "$GITHUB_OUTPUT"
 
   build:
-    name: Build ${{ matrix.target }}
+    name: Build ${{ matrix.variant }} ${{ matrix.target }}
     needs: metadata
     runs-on: ${{ matrix.runner }}
     permissions:
@@ -65,10 +65,34 @@ jobs:
         include:
           - runner: ubuntu-24.04
             platform: linux_amd64_musl
+            sandbox: false
             target: x86_64-unknown-linux-musl
+            variant: release
           - runner: ubuntu-24.04-arm
             platform: linux_arm64_musl
+            sandbox: false
             target: aarch64-unknown-linux-musl
+            variant: release
+          - runner: ubuntu-24.04
+            platform: linux_amd64_musl
+            sandbox: true
+            target: x86_64-unknown-linux-musl
+            variant: ptrcomp-sandbox
+          - runner: ubuntu-24.04-arm
+            platform: linux_arm64_musl
+            sandbox: true
+            target: aarch64-unknown-linux-musl
+            variant: ptrcomp-sandbox
+          - runner: ubuntu-24.04
+            platform: windows_amd64
+            sandbox: true
+            target: x86_64-pc-windows-msvc
+            variant: ptrcomp-sandbox
+          - runner: ubuntu-24.04-arm
+            platform: windows_arm64
+            sandbox: true
+            target: aarch64-pc-windows-msvc
+            variant: ptrcomp-sandbox
 
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -89,13 +113,20 @@ jobs:
         env:
           BUILDBUDDY_API_KEY: ${{ secrets.BUILDBUDDY_API_KEY }}
           PLATFORM: ${{ matrix.platform }}
+          SANDBOX: ${{ matrix.sandbox }}
           TARGET: ${{ matrix.target }}
         shell: bash
         run: |
           set -euo pipefail
 
           target_suffix="${TARGET//-/_}"
-          pair_target="//third_party/v8:rusty_v8_release_pair_${target_suffix}"
+          pair_kind="release_pair"
+          bazel_config_args=(--config=v8-release-compat)
+          if [[ "${SANDBOX}" == "true" ]]; then
+            pair_kind="sandbox_release_pair"
+            bazel_config_args=()
+          fi
+          pair_target="//third_party/v8:rusty_v8_${pair_kind}_${target_suffix}"
           extra_targets=()
           if [[ "${TARGET}" == *-unknown-linux-musl ]]; then
             extra_targets=(
@@ -109,7 +140,7 @@ jobs:
             -c
             opt
             "--platforms=@llvm//platforms:${PLATFORM}"
-            --config=v8-release-compat
+            "${bazel_config_args[@]}"
             "${pair_target}"
             "${extra_targets[@]}"
             --build_metadata=COMMIT_SHA=$(git rev-parse HEAD)
@@ -124,28 +155,138 @@ jobs:
       - name: Stage release pair
         env:
           PLATFORM: ${{ matrix.platform }}
+          SANDBOX: ${{ matrix.sandbox }}
           TARGET: ${{ matrix.target }}
         shell: bash
         run: |
           set -euo pipefail
 
-          python3 .github/scripts/rusty_v8_bazel.py stage-release-pair \
-            --platform "${PLATFORM}" \
-            --target "${TARGET}" \
-            --compilation-mode opt \
-            --bazel-config v8-release-compat \
+          stage_args=(
+            --platform "${PLATFORM}"
+            --target "${TARGET}"
+            --compilation-mode opt
             --output-dir "dist/${TARGET}"
+          )
+          if [[ "${SANDBOX}" == "true" ]]; then
+            stage_args+=(--sandbox)
+          else
+            stage_args+=(--bazel-config v8-release-compat)
+          fi
 
-      - name: Upload staged musl artifacts
+          python3 .github/scripts/rusty_v8_bazel.py stage-release-pair "${stage_args[@]}"
+
+      - name: Upload staged artifacts
         uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
         with:
-          name: rusty-v8-${{ needs.metadata.outputs.v8_version }}-${{ matrix.target }}
+          name: rusty-v8-${{ needs.metadata.outputs.v8_version }}-${{ matrix.variant }}-${{ matrix.target }}
           path: dist/${{ matrix.target }}/*
 
+  validate-sandbox:
+    name: Validate sandbox artifacts - ${{ matrix.target }}
+    needs:
+      - metadata
+      - build
+    runs-on: ${{ matrix.runs_on }}
+    defaults:
+      run:
+        working-directory: codex-rs
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - target: x86_64-unknown-linux-musl
+            exe_suffix: ""
+            runs_on:
+              group: codex-runners
+              labels: codex-linux-x64
+          - target: aarch64-unknown-linux-musl
+            exe_suffix: ""
+            runs_on:
+              group: codex-runners
+              labels: codex-linux-arm64
+          - target: x86_64-pc-windows-msvc
+            exe_suffix: ".exe"
+            runs_on:
+              group: codex-runners
+              labels: codex-windows-x64
+          - target: aarch64-pc-windows-msvc
+            exe_suffix: ".exe"
+            runs_on:
+              group: codex-runners
+              labels: codex-windows-arm64
+
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
+
+      - if: ${{ runner.os == 'Linux' }}
+        name: Install Linux build dependencies
+        shell: bash
+        run: |
+          set -euo pipefail
+          sudo apt-get update -y
+          sudo DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends \
+            pkg-config \
+            libcap-dev
+
+      - uses: dtolnay/rust-toolchain@a0b273b48ed29de4470960879e8381ff45632f26 # 1.93.0
+        with:
+          targets: ${{ matrix.target }}
+
+      - name: Download staged sandbox artifacts
+        uses: actions/download-artifact@3e5f45b2cfb9172054b4087a40e8e0b5a5461e7c # v8
+        with:
+          name: rusty-v8-${{ needs.metadata.outputs.v8_version }}-ptrcomp-sandbox-${{ matrix.target }}
+          path: ${{ runner.temp }}/rusty_v8_sandbox
+
+      - name: Configure sandboxed rusty_v8 artifact overrides
+        env:
+          ARTIFACT_DIR: ${{ runner.temp }}/rusty_v8_sandbox
+          TARGET: ${{ matrix.target }}
+        shell: bash
+        run: |
+          set -euo pipefail
+
+          artifact_profile="ptrcomp_sandbox_release"
+          binding_path="${ARTIFACT_DIR}/src_binding_${artifact_profile}_${TARGET}.rs"
+          checksums_path="${ARTIFACT_DIR}/rusty_v8_${artifact_profile}_${TARGET}.sha256"
+
+          if [[ "${TARGET}" == *-pc-windows-msvc ]]; then
+            archive_name="rusty_v8_${artifact_profile}_${TARGET}.lib.gz"
+          else
+            archive_name="librusty_v8_${artifact_profile}_${TARGET}.a.gz"
+          fi
+          archive_path="${ARTIFACT_DIR}/${archive_name}"
+
+          if [[ "$(wc -l < "${checksums_path}")" -ne 2 ]]; then
+            echo "Expected exactly two checksums for ${TARGET} in ${checksums_path}" >&2
+            exit 1
+          fi
+
+          (cd "${ARTIFACT_DIR}" && sha256sum -c "${checksums_path}")
+          echo "RUSTY_V8_ARCHIVE=${archive_path}" >> "${GITHUB_ENV}"
+          echo "RUSTY_V8_SRC_BINDING_PATH=${binding_path}" >> "${GITHUB_ENV}"
+
+      - name: Run sandboxed V8 probe tests
+        shell: bash
+        run: cargo test -p codex-v8-poc --target "${{ matrix.target }}" --features sandbox
+
+      - name: Run sandboxed code-mode tests
+        shell: bash
+        run: cargo test -p codex-code-mode --target "${{ matrix.target }}" --features sandbox
+
+      - name: Build release binary against sandboxed artifacts
+        shell: bash
+        run: cargo build --target "${{ matrix.target }}" --release --bin codex
+
+      - name: Smoke release binary
+        shell: bash
+        run: "target/${{ matrix.target }}/release/codex${{ matrix.exe_suffix }} --version"
+
   publish-release:
     needs:
       - metadata
       - build
+      - validate-sandbox
     runs-on: ubuntu-latest
     permissions:
       contents: write
diff --git a/.github/workflows/v8-canary.yml b/.github/workflows/v8-canary.yml
index 6e71367d1f..32e529b731 100644
--- a/.github/workflows/v8-canary.yml
+++ b/.github/workflows/v8-canary.yml
@@ -71,10 +71,24 @@ jobs:
         include:
           - runner: ubuntu-24.04
             platform: linux_amd64_musl
+            sandbox: false
             target: x86_64-unknown-linux-musl
+            variant: release
+          - runner: ubuntu-24.04
+            platform: linux_amd64_musl
+            sandbox: true
+            target: x86_64-unknown-linux-musl
+            variant: ptrcomp-sandbox
           - runner: ubuntu-24.04-arm
             platform: linux_arm64_musl
+            sandbox: false
             target: aarch64-unknown-linux-musl
+            variant: release
+          - runner: ubuntu-24.04-arm
+            platform: linux_arm64_musl
+            sandbox: true
+            target: aarch64-unknown-linux-musl
+            variant: ptrcomp-sandbox
 
     steps:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
@@ -96,13 +110,20 @@ jobs:
         env:
           BUILDBUDDY_API_KEY: ${{ secrets.BUILDBUDDY_API_KEY }}
           PLATFORM: ${{ matrix.platform }}
+          SANDBOX: ${{ matrix.sandbox }}
           TARGET: ${{ matrix.target }}
         shell: bash
         run: |
           set -euo pipefail
 
           target_suffix="${TARGET//-/_}"
-          pair_target="//third_party/v8:rusty_v8_release_pair_${target_suffix}"
+          pair_kind="release_pair"
+          bazel_config_args=(--config=v8-release-compat)
+          if [[ "${SANDBOX}" == "true" ]]; then
+            pair_kind="sandbox_release_pair"
+            bazel_config_args=()
+          fi
+          pair_target="//third_party/v8:rusty_v8_${pair_kind}_${target_suffix}"
           extra_targets=(
             "@llvm//runtimes/libcxx:libcxx.static"
             "@llvm//runtimes/libcxx:libcxxabi.static"
@@ -111,7 +132,7 @@ jobs:
           bazel_args=(
             build
             "--platforms=@llvm//platforms:${PLATFORM}"
-            --config=v8-release-compat
+            "${bazel_config_args[@]}"
             "${pair_target}"
             "${extra_targets[@]}"
             --build_metadata=COMMIT_SHA=$(git rev-parse HEAD)
@@ -126,19 +147,27 @@ jobs:
       - name: Stage release pair
         env:
           PLATFORM: ${{ matrix.platform }}
+          SANDBOX: ${{ matrix.sandbox }}
           TARGET: ${{ matrix.target }}
         shell: bash
         run: |
           set -euo pipefail
 
-          python3 .github/scripts/rusty_v8_bazel.py stage-release-pair \
-            --platform "${PLATFORM}" \
-            --target "${TARGET}" \
-            --bazel-config v8-release-compat \
+          stage_args=(
+            --platform "${PLATFORM}"
+            --target "${TARGET}"
             --output-dir "dist/${TARGET}"
+          )
+          if [[ "${SANDBOX}" == "true" ]]; then
+            stage_args+=(--sandbox)
+          else
+            stage_args+=(--bazel-config v8-release-compat)
+          fi
+
+          python3 .github/scripts/rusty_v8_bazel.py stage-release-pair "${stage_args[@]}"
 
       - name: Upload staged musl artifacts
         uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f # v7.0.0
         with:
-          name: v8-canary-${{ needs.metadata.outputs.v8_version }}-${{ matrix.target }}
+          name: v8-canary-${{ needs.metadata.outputs.v8_version }}-${{ matrix.variant }}-${{ matrix.target }}
           path: dist/${{ matrix.target }}/*
diff --git a/third_party/v8/BUILD.bazel b/third_party/v8/BUILD.bazel
index d6aa4c2cc9..e2f1a19c9f 100644
--- a/third_party/v8/BUILD.bazel
+++ b/third_party/v8/BUILD.bazel
@@ -364,6 +364,18 @@ cc_static_library(
     features = V8_STATIC_LIBRARY_FEATURES,
 )
 
+cc_static_library(
+    name = "v8_147_4_0_aarch64_pc_windows_msvc_bazel",
+    deps = [":v8_147_4_0_binding"],
+    features = V8_STATIC_LIBRARY_FEATURES,
+)
+
+cc_static_library(
+    name = "v8_147_4_0_x86_64_pc_windows_msvc_bazel",
+    deps = [":v8_147_4_0_binding"],
+    features = V8_STATIC_LIBRARY_FEATURES,
+)
+
 filegroup(
     name = "src_binding_release_aarch64_unknown_linux_musl_147_4_0_release",
     srcs = ["@v8_crate_147_4_0//:src_binding_release_aarch64_unknown_linux_gnu"],
@@ -374,6 +386,16 @@ filegroup(
     srcs = ["@v8_crate_147_4_0//:src_binding_release_x86_64_unknown_linux_gnu"],
 )
 
+filegroup(
+    name = "src_binding_release_aarch64_pc_windows_msvc_147_4_0_release",
+    srcs = ["@v8_crate_147_4_0//:src_binding_release_aarch64_pc_windows_msvc"],
+)
+
+filegroup(
+    name = "src_binding_release_x86_64_pc_windows_msvc_147_4_0_release",
+    srcs = ["@v8_crate_147_4_0//:src_binding_release_x86_64_pc_windows_msvc"],
+)
+
 filegroup(
     name = "rusty_v8_release_pair_x86_64_apple_darwin",
     srcs = [
@@ -437,3 +459,35 @@ filegroup(
         ":src_binding_release_aarch64_pc_windows_msvc",
     ],
 )
+
+filegroup(
+    name = "rusty_v8_sandbox_release_pair_x86_64_unknown_linux_musl",
+    srcs = [
+        ":v8_147_4_0_x86_64_unknown_linux_musl_release",
+        ":src_binding_release_x86_64_unknown_linux_musl_147_4_0_release",
+    ],
+)
+
+filegroup(
+    name = "rusty_v8_sandbox_release_pair_aarch64_unknown_linux_musl",
+    srcs = [
+        ":v8_147_4_0_aarch64_unknown_linux_musl_release",
+        ":src_binding_release_aarch64_unknown_linux_musl_147_4_0_release",
+    ],
+)
+
+filegroup(
+    name = "rusty_v8_sandbox_release_pair_x86_64_pc_windows_msvc",
+    srcs = [
+        ":v8_147_4_0_x86_64_pc_windows_msvc_bazel",
+        ":src_binding_release_x86_64_pc_windows_msvc_147_4_0_release",
+    ],
+)
+
+filegroup(
+    name = "rusty_v8_sandbox_release_pair_aarch64_pc_windows_msvc",
+    srcs = [
+        ":v8_147_4_0_aarch64_pc_windows_msvc_bazel",
+        ":src_binding_release_aarch64_pc_windows_msvc_147_4_0_release",
+    ],
+)
diff --git a/third_party/v8/README.md b/third_party/v8/README.md
index bd4e108754..96be904ff2 100644
--- a/third_party/v8/README.md
+++ b/third_party/v8/README.md
@@ -40,7 +40,7 @@ The consumer-facing selectors are:
 - `//third_party/v8:rusty_v8_archive_for_target`
 - `//third_party/v8:rusty_v8_binding_for_target`
 
-Musl release assets are expected at the tag:
+Current musl release assets are expected at the tag:
 
 - `rusty-v8-v<crate_version>`
 
@@ -49,13 +49,32 @@ with these raw asset names:
 - `librusty_v8_release_<target>.a.gz`
 - `src_binding_release_<target>.rs`
 
+During the sandbox rollout, sandbox-enabled assets are published alongside those
+current assets on the same tag, with the Rust crate's sandbox feature suffix in
+their raw names:
+
+- `librusty_v8_ptrcomp_sandbox_release_<target>.a.gz`
+- `rusty_v8_ptrcomp_sandbox_release_<target>.lib.gz`
+- `src_binding_ptrcomp_sandbox_release_<target>.rs`
+
 The dedicated publishing workflow is `.github/workflows/rusty-v8-release.yml`.
-It builds musl release pairs from source and keeps the release artifacts as the
-statically linked form:
+Every tagged run builds the current musl release pairs from source and keeps the
+release artifacts as the statically linked form:
 
 - `//third_party/v8:rusty_v8_release_pair_x86_64_unknown_linux_musl`
 - `//third_party/v8:rusty_v8_release_pair_aarch64_unknown_linux_musl`
 
+The same run also builds the matching sandbox pair targets:
+
+- `//third_party/v8:rusty_v8_sandbox_release_pair_x86_64_unknown_linux_musl`
+- `//third_party/v8:rusty_v8_sandbox_release_pair_aarch64_unknown_linux_musl`
+- `//third_party/v8:rusty_v8_sandbox_release_pair_x86_64_pc_windows_msvc`
+- `//third_party/v8:rusty_v8_sandbox_release_pair_aarch64_pc_windows_msvc`
+
+The workflow validates the staged sandbox outputs before publication by checking
+the emitted checksums, running the focused V8/code-mode sandbox tests, and smoke
+starting a release `codex` binary on every supported artifact target.
+
 Cargo musl builds use `RUSTY_V8_ARCHIVE` plus a downloaded
 `RUSTY_V8_SRC_BINDING_PATH` to point at those `openai/codex` release assets
 directly. We do not use `RUSTY_V8_MIRROR` for musl because the upstream `v8`