diff --git a/.clusterfuzzlite/Dockerfile b/.clusterfuzzlite/Dockerfile
index 2a67e0c..0ff21a1 100644
--- a/.clusterfuzzlite/Dockerfile
+++ b/.clusterfuzzlite/Dockerfile
@@ -1,7 +1,9 @@
 # ClusterFuzzLite build image — OpenSSF Scorecard detects fuzzing via this file.
 # Uses the OSS-Fuzz JavaScript base builder (Jazzer.js), which provides
 # `compile_javascript_fuzzer`. See build.sh for the fuzz targets.
-FROM gcr.io/oss-fuzz-base/base-builder-javascript
+# Base pinned by digest (Scorecard Pinned-Dependencies). OSS-Fuzz rolls this
+# image, so bump the digest periodically if the weekly fuzz build breaks.
+FROM gcr.io/oss-fuzz-base/base-builder-javascript@sha256:717f88cd72ee85ab295debf1272eed85590621d6ba9d70d6c59133a61f3f3acf
 COPY . $SRC/truecopy
 WORKDIR $SRC/truecopy
 COPY .clusterfuzzlite/build.sh $SRC/build.sh
diff --git a/.clusterfuzzlite/build.sh b/.clusterfuzzlite/build.sh
index 21ff40e..c58a6f8 100755
--- a/.clusterfuzzlite/build.sh
+++ b/.clusterfuzzlite/build.sh
@@ -7,7 +7,9 @@
 # `vetted`, and the poison scanner always returns a well-formed verdict on any
 # malformed skill.
 cd "$SRC/truecopy"
-npm install --no-audit --no-fund
+# npm ci verifies every integrity hash in the committed lockfile
+# (Scorecard Pinned-Dependencies); Jazzer comes in as the locked devDependency.
+npm ci --no-audit --no-fund
 
 for target in canonical_json gate_tools scan_skill; do
   compile_javascript_fuzzer truecopy "fuzz/${target}.fuzz.js" --sync
diff --git a/.github/workflows/auto-release.yml b/.github/workflows/auto-release.yml
index 53257b6..11eb367 100644
--- a/.github/workflows/auto-release.yml
+++ b/.github/workflows/auto-release.yml
@@ -30,6 +30,8 @@ jobs:
     permissions:
       contents: write # push the tag + create the GitHub release
       actions: write # dispatch publish.yml
+      id-token: write # keyless Sigstore signing (attest-build-provenance)
+      attestations: write # persist the attestation in GitHub's store
     steps:
       - uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7.0.0
         with:
@@ -148,6 +150,34 @@ jobs:
             --title "$TAG" \
             --notes-file release-notes.md
 
+      - name: Build npm tarball (release artifact)
+        if: steps.gate.outputs.skip != 'true' && steps.bumped.outputs.skip != 'true'
+        id: pack
+        run: |
+          set -euo pipefail
+          tarball=$(npm pack --silent)
+          echo "tarball=${tarball}" >> "$GITHUB_OUTPUT"
+          sha256sum "$tarball"
+
+      - name: Attest build provenance (keyless Sigstore)
+        if: steps.gate.outputs.skip != 'true' && steps.bumped.outputs.skip != 'true'
+        id: attest
+        uses: actions/attest-build-provenance@0f67c3f4856b2e3261c31976d6725780e5e4c373 # v4.1.1
+        with:
+          subject-path: ${{ steps.pack.outputs.tarball }}
+
+      - name: Upload tarball + provenance bundle to the release
+        if: steps.gate.outputs.skip != 'true' && steps.bumped.outputs.skip != 'true'
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+          TAG: ${{ steps.version.outputs.tag }}
+          TARBALL: ${{ steps.pack.outputs.tarball }}
+          BUNDLE: ${{ steps.attest.outputs.bundle-path }}
+        run: |
+          set -euo pipefail
+          cp "$BUNDLE" "${TARBALL}.sigstore.json"
+          gh release upload "$TAG" --clobber "$TARBALL" "${TARBALL}.sigstore.json"
+
       - name: Hand off to the OIDC publisher
         if: steps.gate.outputs.skip != 'true' && steps.bumped.outputs.skip != 'true'
         env: