diff --git a/agent-base/Dockerfile b/agent-base/Dockerfile
index e89caed007..2ff26dfd0b 100644
--- a/agent-base/Dockerfile
+++ b/agent-base/Dockerfile
@@ -1,4 +1,5 @@
 # syntax=docker/dockerfile:1.7
+FROM ghcr.io/pasturestack/ubuntu-security-backports:v0.1.0@sha256:2742a3d429e4e14bc587f6dedc51ded4246cf90bbaedcd86c67d0885e32a6f2a AS ubuntu_security_backports
 FROM ubuntu:26.04@sha256:2260313b31c8c011cd2eebe728008efac1b3982be73eb71348ea2648d2c0e09b AS python-builder
 
 RUN rm -f /usr/bin/pebble
@@ -69,7 +70,7 @@ ARG VCS_REF
 LABEL org.opencontainers.image.source="https://github.com/PastureStack/server" \
       org.opencontainers.image.description="PastureStack node-agent compatibility base image." \
       org.opencontainers.image.licenses="Apache-2.0" \
-      org.opencontainers.image.version="v0.3.6" \
+      org.opencontainers.image.version="v0.3.7" \
       org.opencontainers.image.revision="$VCS_REF"
 
 RUN rm -f /usr/bin/pebble
@@ -147,4 +148,20 @@ RUN rm -f /etc/apt/sources.list /etc/apt/sources.list.d/*.list /etc/apt/sources.
     rm /var/run && \
     mkdir /var/run
 
+# Only the final runtime consumes these qualified packages. Keep the Python
+# compiler stage and the existing coreutils provider unchanged.
+RUN --mount=from=ubuntu_security_backports,source=/out,target=/opt/pasturestack/ubuntu-security-backports,ro \
+    set -eux; \
+    data=/opt/pasturestack/ubuntu-security-backports; \
+    evidence=/usr/share/pasturestack/security/ubuntu-backports; \
+    mkdir -p "$evidence"; \
+    "$data/install-existing-backports" --install-in-docker-build > "$evidence/install.json"; \
+    "$data/install-existing-backports" --verify-installed > "$evidence/verify.json"; \
+    for name in manifest.json qualification.json source-inputs.lock.json openvex.json; do \
+        install -m 0644 "$data/$name" "$evidence/$name"; \
+    done; \
+    printf '%s\n' 'ghcr.io/pasturestack/ubuntu-security-backports:v0.1.0@sha256:2742a3d429e4e14bc587f6dedc51ded4246cf90bbaedcd86c67d0885e32a6f2a' > "$evidence/bundle-image.txt"; \
+    cd "$evidence"; \
+    sha256sum manifest.json qualification.json openvex.json source-inputs.lock.json install.json verify.json bundle-image.txt > SHA256SUMS
+
 ENTRYPOINT ["/pasturestack-entrypoint.sh"]
diff --git a/agent-base/README.md b/agent-base/README.md
index 45d566fa88..6a65bc98f2 100644
--- a/agent-base/README.md
+++ b/agent-base/README.md
@@ -1,10 +1,18 @@
 # Node agent image builds
 
-The compatibility base targets `ghcr.io/pasturestack/node-agent-base:v0.3.6`.
+The compatibility base targets `ghcr.io/pasturestack/node-agent-base:v0.3.7`.
 It builds Python 3.14.9 from the official SHA-256-verified archive, retains
 Docker CLI 29.9.2 (official Go 1.26.10 build), and uses the fixed Ubuntu 26.04 snapshot
 `20261023T000000Z`. Builder and runtime package inventories are compared;
-the runtime verifies the patched OpenSSL, curl, libc and CA package versions.
+only exact qualified security-backport versions may differ in the final runtime.
+The Python compiler stage keeps its original libc. The runtime verifies the
+patched OpenSSL, curl, libc and CA package versions.
+
+The digest-pinned, build-only Ubuntu backport bundle updates only already
+installed packages, preserving the existing coreutils provider and package set.
+Its source/native-test qualification, package manifest and installation receipt
+are retained under `/usr/share/pasturestack/security/ubuntu-backports/`.
+The bundle and installer are read-only build mounts, not runtime dependencies.
 
 The shared `tools/pip-security-overlay` helper builds the clearly identified
 downstream wheel `pip 26.2.2+pasturestack.1` from pinned official inputs using
diff --git a/agent-base/build-image.sh b/agent-base/build-image.sh
index b8ae5b65a2..f1c3a2a6c4 100755
--- a/agent-base/build-image.sh
+++ b/agent-base/build-image.sh
@@ -3,7 +3,7 @@ set -euo pipefail
 
 cd "$(dirname "$0")"
 
-IMAGE=${IMAGE:-ghcr.io/pasturestack/node-agent-base:v0.3.6}
+IMAGE=${IMAGE:-ghcr.io/pasturestack/node-agent-base:v0.3.7}
 
 SHARE_MNT_BIN="${SHARE_MNT_BIN:-}"
 if [ -z "$SHARE_MNT_BIN" ] || [ ! -f "$SHARE_MNT_BIN" ]; then
diff --git a/scripts/build-agent-release.sh b/scripts/build-agent-release.sh
index a7f258f48f..e7791f1228 100644
--- a/scripts/build-agent-release.sh
+++ b/scripts/build-agent-release.sh
@@ -10,9 +10,10 @@ test "$source_sha" = "$GITHUB_SHA"
 evidence=${EVIDENCE_DIR:?EVIDENCE_DIR is required}
 mkdir -p "$evidence"
 printf '%s\n' "$source_sha" >"$evidence/source-revision.txt"
+python3 scripts/test-agent-package-consistency.py
 
 case "${COMPONENT:-}" in
-  base) repository=ghcr.io/pasturestack/node-agent-base; version=v0.3.6 ;;
+  base) repository=ghcr.io/pasturestack/node-agent-base; version=v0.3.7 ;;
   agent) repository=ghcr.io/pasturestack/node-agent; version=v1.2.32 ;;
   *) echo 'Unsupported agent component' >&2; exit 1 ;;
 esac
@@ -20,8 +21,12 @@ esac
 target="$repository:$version"
 candidate="local/pasturestack-node-agent-${COMPONENT}:${GITHUB_RUN_ID}"
 helper_container="pasturestack-agent-helper-${GITHUB_RUN_ID}"
+backports_container=
+bundle_container=
 scratch=$(mktemp -d)
 cleanup() {
+  if [[ -n "$backports_container" ]]; then docker rm -v "$backports_container" >/dev/null 2>&1 || true; fi
+  if [[ -n "$bundle_container" ]]; then docker rm -v "$bundle_container" >/dev/null 2>&1 || true; fi
   docker rm -v "$helper_container" >/dev/null 2>&1 || true
   docker logout ghcr.io >/dev/null 2>&1 || true
   rm -rf "$scratch"
@@ -76,23 +81,32 @@ docker run --rm --network none --entrypoint cat "$candidate" \
   /usr/share/pasturestack/python-builder-packages.tsv >"$evidence/builder-packages.tsv"
 docker run --rm --network none --entrypoint dpkg-query "$candidate" \
   -W -f='${binary:Package}\t${Version}\n' >"$evidence/runtime-packages.tsv"
-python3 - "$evidence" <<'PY'
-from pathlib import Path
-import json, sys
-root = Path(sys.argv[1])
-def packages(name):
-    return dict(line.split('\t', 1) for line in (root / name).read_text().splitlines())
-builder, runtime = packages('builder-packages.tsv'), packages('runtime-packages.tsv')
-common = builder.keys() & runtime.keys()
-assert all(builder[name] == runtime[name] for name in common), 'builder/runtime package drift'
-for package, version in {'libssl3t64:amd64': '3.5.5-1ubuntu3.7', 'curl': '8.18.0-1ubuntu2.8',
-                         'libc6:amd64': '2.43-2ubuntu2.4', 'ca-certificates': '20260816ubuntu0.26.04.1'}.items():
-    assert runtime.get(package) == version, (package, runtime.get(package), version)
-report = {'builder_packages': len(builder), 'runtime_packages': len(runtime),
-          'common_packages_same_versions': len(common), 'expected_security_packages': True}
-(root / 'package-comparison.json').write_text(json.dumps(report, indent=2) + '\n')
-print(json.dumps(report))
-PY
+if [[ "$COMPONENT" = base ]]; then
+  for name in manifest qualification install; do
+    docker run --rm --network none --entrypoint cat "$candidate" \
+      "/usr/share/pasturestack/security/ubuntu-backports/${name}.json" >"$evidence/backports-${name}.json"
+  done
+  jq -n --rawfile builder "$evidence/builder-packages.tsv" \
+    --rawfile runtime "$evidence/runtime-packages.tsv" \
+    --rawfile manifest "$evidence/backports-manifest.json" \
+    --rawfile qualification "$evidence/backports-qualification.json" \
+    --rawfile installation "$evidence/backports-install.json" \
+    '{"builder-packages.tsv":$builder,"runtime-packages.tsv":$runtime,
+      "backports-manifest.json":$manifest,"backports-qualification.json":$qualification,
+      "backports-install.json":$installation}' \
+    | python3 scripts/check-agent-package-consistency.py >"$evidence/package-comparison.json"
+  backports_container=$(docker create "$candidate")
+  docker cp "$backports_container:/usr/share/pasturestack/security/ubuntu-backports" "$evidence/ubuntu-backports"
+  docker rm -v "$backports_container" >/dev/null
+  backports_container=
+else
+  # The wrapper remains pinned to the published 0.3.6 base until 0.3.7 passes
+  # publication. Its existing strict checks must continue to work meanwhile.
+  jq -n --rawfile builder "$evidence/builder-packages.tsv" \
+    --rawfile runtime "$evidence/runtime-packages.tsv" \
+    '{"builder-packages.tsv":$builder,"runtime-packages.tsv":$runtime}' \
+    | python3 scripts/check-agent-package-consistency.py --legacy-wrapper >"$evidence/package-comparison.json"
+fi
 docker run --rm --network none --entrypoint /bin/bash "$candidate" -ec \
   'ldd "$(python3 -c "import _ssl; print(_ssl.__file__)")"; curl --version' \
   >"$evidence/python-ssl-linkage.txt"
@@ -121,14 +135,38 @@ docker run --rm --entrypoint python3 "$candidate" -c \
 
 trivy=ghcr.io/aquasecurity/trivy:0.74.0@sha256:62b1e65e8869bc4b4c6aa4fa2b21595256c7c2f6018a9d9ad61caf87187c1969
 docker pull "$trivy"
+mkdir -p "$scratch/trivy-cache"
 docker run --rm -v /var/run/docker.sock:/var/run/docker.sock \
-  -v "$evidence:/evidence" "$trivy" image --format cyclonedx \
+  -v "$scratch/trivy-cache:/root/.cache/trivy" -v "$evidence:/evidence" "$trivy" image --format cyclonedx \
   --output /evidence/image.cdx.json "$candidate"
 docker run --rm -v /var/run/docker.sock:/var/run/docker.sock \
-  -v "$evidence:/evidence" "$trivy" image --scanners vuln,secret --list-all-pkgs --format json \
+  -v "$scratch/trivy-cache:/root/.cache/trivy" -v "$evidence:/evidence" "$trivy" image --scanners vuln,secret --list-all-pkgs --format json \
   --output /evidence/image-security.json "$candidate"
+pip_scan_input="$evidence/image-security.json"
+if [[ "$COMPONENT" = base ]]; then
+backports_image=$(sed -n 's/^FROM \(ghcr.io\/pasturestack\/ubuntu-security-backports:v0\.1\.0@sha256:[0-9a-f]\{64\}\) AS ubuntu_security_backports$/\1/p' agent-base/Dockerfile)
+[[ "$backports_image" =~ ^ghcr.io/pasturestack/ubuntu-security-backports:v0\.1\.0@sha256:[0-9a-f]{64}$ ]]
+docker pull --platform linux/amd64 "$backports_image"
+bundle_container=$(docker create --entrypoint /unused "$backports_image")
+docker cp "$bundle_container:/out/verify-consumer-evidence.py" "$scratch/verify-consumer-evidence.py"
+docker cp "$bundle_container:/out/SHA256SUMS" "$scratch/backports-SHA256SUMS"
+docker rm "$bundle_container" >/dev/null
+bundle_container=
+python3 "$scratch/verify-consumer-evidence.py" --evidence-dir "$evidence/ubuntu-backports" \
+  --sbom "$evidence/image.cdx.json" --expected-bundle-digest "${backports_image##*@}" \
+  --bundle-checksums "$scratch/backports-SHA256SUMS" \
+  >"$evidence/ubuntu-backports-consumer-proof.json"
+# Preserve the original full scan. Native Trivy applies only the qualified,
+# exact-package OpenVEX, followed by the existing pip-vendor interpretation.
+docker run --rm -v /var/run/docker.sock:/var/run/docker.sock \
+  -v "$scratch/trivy-cache:/root/.cache/trivy" -v "$evidence:/evidence" "$trivy" image \
+  --scanners vuln,secret --list-all-pkgs --skip-db-update --skip-vex-repo-update \
+  --vex /evidence/ubuntu-backports/openvex.json --format json \
+  --output /evidence/image-security-os-effective.json "$candidate"
+pip_scan_input="$evidence/image-security-os-effective.json"
+fi
 python3 tools/pip-security-overlay/filter-pip-vendor-findings.py \
-  --raw "$evidence/image-security.json" --proof "$evidence/pip-vendor-slice.json" \
+  --raw "$pip_scan_input" --proof "$evidence/pip-vendor-slice.json" \
   --output "$evidence/image-security-effective.json" --vex "$evidence/image.vex.json" \
   --subject "urn:sha256:${local_id#sha256:}"
 python3 - "$evidence" <<'PY'
@@ -164,7 +202,7 @@ if [[ "$PUBLISH" = true ]]; then
   docker pull "$repository@$digest"
   test "$(docker image inspect "$repository@$digest" --format '{{.Id}}')" = "$local_id"
   python3 tools/pip-security-overlay/filter-pip-vendor-findings.py \
-    --raw "$evidence/image-security.json" --proof "$evidence/pip-vendor-slice.json" \
+    --raw "$pip_scan_input" --proof "$evidence/pip-vendor-slice.json" \
     --output "$evidence/image-security-effective.json" --vex "$evidence/image.vex.json" \
     --subject "https://ghcr.io/v2/${repository#ghcr.io/}/manifests/$digest"
   printf 'repository=%s\nversion=%s\nsource=%s\ndigest=%s\nimage_id=%s\n' \
diff --git a/scripts/check-agent-package-consistency.py b/scripts/check-agent-package-consistency.py
new file mode 100644
index 0000000000..5005566c8e
--- /dev/null
+++ b/scripts/check-agent-package-consistency.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python3
+"""Compare the real Python builder/runtime inventories and qualified deltas."""
+import hashlib
+import json
+import sys
+
+
+def require(value, message):
+    if not value:
+        raise ValueError(message)
+
+
+def inventory(text):
+    require(isinstance(text, str), 'Package inventory must be text')
+    rows = [line.split('\t') for line in text.splitlines()]
+    require(all(len(row) == 2 for row in rows), 'Malformed package inventory')
+    result = {name.split(':', 1)[0]: version for name, version in rows}
+    require(len(result) == len(rows), 'Duplicate/multiarch package inventory')
+    return result
+
+
+def verify_legacy_wrapper(data):
+    """Preserve the published 0.3.6 wrapper contract until its new base exists."""
+    builder = inventory(data['builder-packages.tsv'])
+    runtime = inventory(data['runtime-packages.tsv'])
+    common = builder.keys() & runtime.keys()
+    require(all(builder[name] == runtime[name] for name in common), 'Legacy wrapper builder/runtime drift')
+    expected = {'libssl3t64': '3.5.5-1ubuntu3.7', 'curl': '8.18.0-1ubuntu2.8',
+                'libc6': '2.43-2ubuntu2.4', 'ca-certificates': '20260816ubuntu0.26.04.1'}
+    require(all(runtime.get(name) == version for name, version in expected.items()),
+            'Unexpected published-wrapper security package')
+    return {'builder_packages': len(builder), 'runtime_packages': len(runtime),
+            'common_packages_same_versions': len(common), 'expected_security_packages': True}
+
+
+def verify(data):
+    builder = inventory(data['builder-packages.tsv'])
+    runtime = inventory(data['runtime-packages.tsv'])
+    manifest_bytes = data['backports-manifest.json'].encode('utf-8')
+    manifest = json.loads(manifest_bytes)
+    qualification_bytes = data['backports-qualification.json'].encode('utf-8')
+    qualification = json.loads(qualification_bytes)
+    receipt = json.loads(data['backports-install.json'])
+    require(manifest['schemaVersion'] == 1 and manifest['bundleVersion'] == '0.1.0'
+            and manifest['platform'] == {'distribution': 'ubuntu', 'release': '26.04', 'architecture': 'amd64'},
+            'Unexpected backport manifest identity')
+    require(manifest['qualification']['sha256'] == hashlib.sha256(qualification_bytes).hexdigest(),
+            'Backport qualification checksum mismatch')
+    fixtures = qualification['consumerFixtures']
+    require(qualification['status'] == 'qualified' and len(fixtures) == 2
+            and {item['provider'] for item in fixtures} == {'gnu', 'uutils'}
+            and all(item['status'] == 'PASS' for item in fixtures),
+            'Backport consumer qualification is incomplete')
+    allowed = {'libc6', 'libc-bin', 'libc-gconv-modules-extra', 'libpcre2-8-0', 'libpcre2-posix3',
+               'rust-coreutils', 'jq', 'libjq1', 'p11-kit', 'p11-kit-modules', 'libp11-kit0', 'libxrender1'}
+    packages = manifest['packages']
+    qualified = {p['name']: p['version'] for p in packages}
+    require(len(packages) == len(qualified) == 12 and set(qualified) == allowed,
+            'Unexpected qualified package catalog')
+    require(receipt['schemaVersion'] == 1 and receipt['bundleVersion'] == '0.1.0'
+            and receipt['status'] == 'installed-and-verified'
+            and receipt['providerPreserved'] is True and receipt['configurationPreserved'] is True,
+            'Runtime installation did not preserve its provider/configuration')
+    selected = set(receipt['packages'])
+    require(len(selected) == len(receipt['packages']) and selected == allowed & runtime.keys(),
+            'Installation receipt does not match the existing runtime package selection')
+    for name in selected:
+        require(runtime[name] == qualified[name], 'Unqualified runtime version: ' + name)
+    common = builder.keys() & runtime.keys()
+    changed = {name for name in common if builder[name] != runtime[name]}
+    require(changed <= selected, 'Unrelated builder/runtime package drift: ' + ', '.join(sorted(changed - selected)))
+    # Keep the original compiler inputs. Only final-runtime library versions
+    # may differ, and only by the exact qualified manifest above.
+    require(builder.get('libc6') == '2.43-2ubuntu2.4', 'Unexpected Python-builder libc version')
+    expected = {'libssl3t64': '3.5.5-1ubuntu3.7', 'curl': '8.18.0-1ubuntu2.8',
+                'ca-certificates': '20260816ubuntu0.26.04.1'}
+    for name, version in expected.items():
+        require(runtime.get(name) == version, 'Unexpected unchanged security package: ' + name)
+    return {'builder_packages': len(builder), 'runtime_packages': len(runtime),
+            'common_packages_same_versions': len(common - changed),
+            'qualified_runtime_deltas': sorted(changed), 'expected_security_packages': True,
+            'backport_manifest_sha256': hashlib.sha256(manifest_bytes).hexdigest()}
+
+
+if __name__ == '__main__':
+    require(sys.argv[1:] in ([], ['--legacy-wrapper']), 'Unsupported arguments')
+    data = json.load(sys.stdin)
+    report = verify_legacy_wrapper(data) if sys.argv[1:] else verify(data)
+    print(json.dumps(report, indent=2))
diff --git a/scripts/test-agent-package-consistency.py b/scripts/test-agent-package-consistency.py
new file mode 100644
index 0000000000..21144e96fe
--- /dev/null
+++ b/scripts/test-agent-package-consistency.py
@@ -0,0 +1,99 @@
+#!/usr/bin/env python3
+import copy
+import hashlib
+import importlib.util
+import json
+from pathlib import Path
+import unittest
+
+spec = importlib.util.spec_from_file_location('package_consistency', Path(__file__).with_name('check-agent-package-consistency.py'))
+module = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(module)
+
+
+class PackageConsistencyTests(unittest.TestCase):
+    def setUp(self):
+        self.data = {}
+        self.versions = {'libc6': '2.43-2ubuntu2.4+pasturestack.1', 'libc-bin': '2.43-2ubuntu2.4+pasturestack.1',
+                         'libc-gconv-modules-extra': '2.43-2ubuntu2.4+pasturestack.1',
+                         'libpcre2-8-0': '10.46-1build1+pasturestack.1', 'libpcre2-posix3': '10.46-1build1+pasturestack.1',
+                         'rust-coreutils': '0.10.0-1ubuntu2~26.04.1+pasturestack.1', 'jq': '1.8.2-0pasturestack1~26.04.1',
+                         'libjq1': '1.8.2-0pasturestack1~26.04.1', 'p11-kit': '0.26.2-2+pasturestack.1',
+                         'p11-kit-modules': '0.26.2-2+pasturestack.1', 'libp11-kit0': '0.26.2-2+pasturestack.1',
+                         'libxrender1': '1:0.9.12-1build1+pasturestack.1'}
+        self.builder = {'libc6': '2.43-2ubuntu2.4', 'libpcre2-8-0': '10.46-1build1',
+                        'libssl3t64': '3.5.5-1ubuntu3.7', 'curl': '8.18.0-1ubuntu2.8',
+                        'ca-certificates': '20260816ubuntu0.26.04.1', 'zlib1g': '1.3.1'}
+        self.runtime = dict(self.builder, libc6=self.versions['libc6'])
+        self.runtime['libpcre2-8-0'] = self.versions['libpcre2-8-0']
+        self.receipt = {'schemaVersion': 1, 'bundleVersion': '0.1.0', 'status': 'installed-and-verified',
+                        'providerPreserved': True, 'configurationPreserved': True,
+                        'packages': ['libc6', 'libpcre2-8-0']}
+        qualification = {'status': 'qualified', 'consumerFixtures': [
+            {'provider': 'gnu', 'status': 'PASS'}, {'provider': 'uutils', 'status': 'PASS'}]}
+        content = (json.dumps(qualification) + '\n').encode()
+        self.data['backports-qualification.json'] = content.decode('utf-8')
+        self.manifest = {'schemaVersion': 1, 'bundleVersion': '0.1.0',
+                         'platform': {'distribution': 'ubuntu', 'release': '26.04', 'architecture': 'amd64'},
+                         'qualification': {'sha256': hashlib.sha256(content).hexdigest()},
+                         'packages': [{'name': name, 'version': version} for name, version in self.versions.items()]}
+
+    def verify(self):
+        for filename, data in [('backports-manifest.json', self.manifest), ('backports-install.json', self.receipt)]:
+            self.data[filename] = json.dumps(data)
+        for filename, data in [('builder-packages.tsv', self.builder), ('runtime-packages.tsv', self.runtime)]:
+            self.data[filename] = ''.join(name + '\t' + version + '\n' for name, version in data.items())
+        return module.verify(self.data)
+
+    def test_only_qualified_final_runtime_differences_pass(self):
+        self.assertEqual(self.verify()['qualified_runtime_deltas'], ['libc6', 'libpcre2-8-0'])
+        self.assertEqual(self.builder['libc6'], '2.43-2ubuntu2.4')
+
+    def test_unrelated_drift_is_rejected(self):
+        self.runtime['zlib1g'] = 'unexpected'
+        with self.assertRaisesRegex(ValueError, 'Unrelated'): self.verify()
+
+    def test_nonqualified_library_version_is_rejected(self):
+        self.runtime['libc6'] = '2.44'
+        with self.assertRaisesRegex(ValueError, 'Unqualified'): self.verify()
+
+    def test_builder_changes_are_not_a_workaround(self):
+        self.builder['libc6'] = self.versions['libc6']
+        with self.assertRaisesRegex(ValueError, 'Python-builder'): self.verify()
+
+    def test_false_selection_or_provider_proof_is_rejected(self):
+        original = copy.deepcopy(self.receipt)
+        for mutate in [lambda r: r['packages'].append('jq'), lambda r: r.update(providerPreserved=False)]:
+            self.receipt = copy.deepcopy(original)
+            mutate(self.receipt)
+            with self.assertRaises(ValueError): self.verify()
+
+    def test_changed_qualification_is_rejected(self):
+        self.data['backports-qualification.json'] = '{}'
+        with self.assertRaisesRegex(ValueError, 'checksum'): self.verify()
+
+    def test_published_wrapper_keeps_its_original_strict_contract(self):
+        self.runtime = dict(self.builder)
+        self.verify_files_only()
+        self.assertTrue(module.verify_legacy_wrapper(self.data)['expected_security_packages'])
+        self.runtime['libc6'] = self.versions['libc6']
+        self.verify_files_only()
+        with self.assertRaisesRegex(ValueError, 'drift'):
+            module.verify_legacy_wrapper(self.data)
+
+    def verify_files_only(self):
+        for filename, data in [('builder-packages.tsv', self.builder), ('runtime-packages.tsv', self.runtime)]:
+            self.data[filename] = ''.join(name + '\t' + version + '\n' for name, version in data.items())
+
+    def test_inventory_text_preserves_bytes_and_rejects_malformed_rows(self):
+        result = self.verify()
+        self.assertEqual(result['backport_manifest_sha256'], hashlib.sha256(
+            self.data['backports-manifest.json'].encode('utf-8')).hexdigest())
+        with self.assertRaisesRegex(ValueError, 'Malformed'):
+            module.inventory('libc6\tversion\textra\n')
+        with self.assertRaisesRegex(ValueError, 'Duplicate'):
+            module.inventory('libc6\tversion\nlibc6:amd64\tversion\n')
+
+
+if __name__ == '__main__':
+    unittest.main(verbosity=2)