From f6d423e2552f7c16f3d74ccf4e5ee7e3e87c76bf Mon Sep 17 00:00:00 2001
From: Rob Taylor <rob.taylor@chipflow.io>
Date: Tue, 10 Mar 2026 17:55:01 +0000
Subject: [PATCH 1/2] Add in-repo action integration tests

Bring the integration tests from the separate cache-apt-pkgs-action-ci
repo into this repo. Tests now use `uses: ./` to test the local checkout
directly, eliminating the need for cross-repo dispatch events.

Tests cover:
- Core workflow: install, restore, cache invalidation, package ordering
- Error handling: empty packages, missing packages, invalid version
- Regression tests: issues #36, #37, #72, #76, #79, #81, #84, #89, #98, #106
- Special cases: multi-arch cache keys, virtual packages

Changes from the external CI tests:
- Uses `uses: ./` instead of `uses: awalsh128/cache-apt-pkgs-action@master`
- Updated checkout to actions/checkout@v4
- Made version-list assertions resilient (grep for expected packages
  rather than exact string match, since dependency versions change
  with Ubuntu updates)
- Improved error-case verification (check outcome != failure rather
  than only running on failure)
- Triggers on push to master/dev/staging and on pull requests

Co-developed-by: Claude Code v2.1.58 (claude-opus-4-6)
---
 .github/workflows/action-tests.yml | 475 +++++++++++++++++++++++++++++
 1 file changed, 475 insertions(+)
 create mode 100644 .github/workflows/action-tests.yml

diff --git a/.github/workflows/action-tests.yml b/.github/workflows/action-tests.yml
new file mode 100644
index 0000000..2fb8ce3
--- /dev/null
+++ b/.github/workflows/action-tests.yml
@@ -0,0 +1,475 @@
+name: Action Tests
+on:
+  workflow_dispatch:
+    inputs:
+      debug:
+        description: "Run in debug mode."
+        type: boolean
+        required: false
+        default: false
+  push:
+    branches: [master, dev, staging]
+  pull_request:
+    types: [opened, synchronize]
+
+env:
+  DEBUG: ${{ github.event.inputs.debug || false }}
+  # Test for overrides in built in shell options (regression issue 98).
+  SHELLOPTS: errexit:pipefail
+
+jobs:
+
+  # === Core Functionality ===
+
+  list_all_versions:
+    runs-on: ubuntu-latest
+    name: List all package versions (including deps).
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: xdot=1.3-1
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-list_all_versions
+          debug: ${{ env.DEBUG }}
+      - name: Verify
+        run: |
+          echo "cache-hit = ${{ steps.execute.outputs.cache-hit }}"
+          echo "package-version-list = ${{ steps.execute.outputs.package-version-list }}"
+          echo "all-package-version-list = ${{ steps.execute.outputs.all-package-version-list }}"
+          # Verify cache miss on first run.
+          test "${{ steps.execute.outputs.cache-hit }}" = "false"
+          # Verify the main package is in the all-packages list.
+          echo "${{ steps.execute.outputs.all-package-version-list }}" | grep -q "xdot=1.3-1"
+        shell: bash
+
+  list_versions:
+    runs-on: ubuntu-latest
+    name: List package versions.
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: xdot rolldice
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-list_versions
+          debug: ${{ env.DEBUG }}
+      - name: Verify
+        run: |
+          echo "cache-hit = ${{ steps.execute.outputs.cache-hit }}"
+          echo "package-version-list = ${{ steps.execute.outputs.package-version-list }}"
+          test "${{ steps.execute.outputs.cache-hit }}" = "false"
+          echo "${{ steps.execute.outputs.package-version-list }}" | grep -q "xdot="
+          echo "${{ steps.execute.outputs.package-version-list }}" | grep -q "rolldice="
+        shell: bash
+
+  standard_workflow_install:
+    runs-on: ubuntu-latest
+    name: Standard workflow install package and cache.
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: xdot rolldice
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-standard_workflow
+          debug: ${{ env.DEBUG }}
+      - name: Verify
+        if: steps.execute.outputs.cache-hit != 'false'
+        run: |
+          echo "cache-hit = ${{ steps.execute.outputs.cache-hit }}"
+          exit 1
+        shell: bash
+
+  standard_workflow_install_with_new_version:
+    needs: standard_workflow_install
+    runs-on: ubuntu-latest
+    name: Standard workflow packages with new version.
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: xdot rolldice
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-standard_workflow_install_with_new_version
+          debug: ${{ env.DEBUG }}
+      - name: Verify
+        if: steps.execute.outputs.cache-hit != 'false'
+        run: |
+          echo "cache-hit = ${{ steps.execute.outputs.cache-hit }}"
+          exit 1
+        shell: bash
+
+  standard_workflow_restore:
+    needs: standard_workflow_install
+    runs-on: ubuntu-latest
+    name: Standard workflow restore cached packages.
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: xdot rolldice
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-standard_workflow
+          debug: ${{ env.DEBUG }}
+      - name: Verify
+        if: steps.execute.outputs.cache-hit != 'true'
+        run: |
+          echo "cache-hit = ${{ steps.execute.outputs.cache-hit }}"
+          exit 1
+        shell: bash
+
+  standard_workflow_restore_with_packages_out_of_order:
+    needs: standard_workflow_install
+    runs-on: ubuntu-latest
+    name: Standard workflow restore with packages out of order.
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: rolldice xdot
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-standard_workflow
+          debug: ${{ env.DEBUG }}
+      - name: Verify
+        if: steps.execute.outputs.cache-hit != 'true'
+        run: |
+          echo "cache-hit = ${{ steps.execute.outputs.cache-hit }}"
+          exit 1
+        shell: bash
+
+  standard_workflow_add_package:
+    needs: standard_workflow_install
+    runs-on: ubuntu-latest
+    name: Standard workflow add another package.
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: xdot rolldice distro-info-data
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-standard_workflow
+          debug: ${{ env.DEBUG }}
+      - name: Verify
+        if: steps.execute.outputs.cache-hit != 'false'
+        run: |
+          echo "cache-hit = ${{ steps.execute.outputs.cache-hit }}"
+          exit 1
+        shell: bash
+
+  standard_workflow_restore_add_package:
+    needs: standard_workflow_add_package
+    runs-on: ubuntu-latest
+    name: Standard workflow restore added package.
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: xdot rolldice distro-info-data
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-standard_workflow
+          debug: ${{ env.DEBUG }}
+      - name: Verify
+        if: steps.execute.outputs.cache-hit != 'true'
+        run: |
+          echo "cache-hit = ${{ steps.execute.outputs.cache-hit }}"
+          exit 1
+        shell: bash
+
+  # === Error Handling ===
+
+  no_packages:
+    runs-on: ubuntu-latest
+    name: No packages passed.
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: ""
+        continue-on-error: true
+      - name: Verify
+        if: steps.execute.outcome != 'failure'
+        run: |
+          echo "Expected failure but got: ${{ steps.execute.outcome }}"
+          exit 1
+        shell: bash
+
+  package_not_found:
+    runs-on: ubuntu-latest
+    name: Package not found.
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: package_that_doesnt_exist
+        continue-on-error: true
+      - name: Verify
+        if: steps.execute.outcome != 'failure'
+        run: |
+          echo "Expected failure but got: ${{ steps.execute.outcome }}"
+          exit 1
+        shell: bash
+
+  version_contains_spaces:
+    runs-on: ubuntu-latest
+    name: Version contains spaces.
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: xdot
+          version: 123 abc
+          debug: ${{ env.DEBUG }}
+        continue-on-error: true
+      - name: Verify
+        if: steps.execute.outcome != 'failure'
+        run: |
+          echo "Expected failure but got: ${{ steps.execute.outcome }}"
+          exit 1
+        shell: bash
+
+  debug_disabled:
+    runs-on: ubuntu-latest
+    name: Debug disabled.
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: xdot
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-debug_disabled
+          debug: false
+
+  # === Regression Tests ===
+
+  regression_36:
+    runs-on: ubuntu-latest
+    name: "Reinstall existing package (regression issue #36)."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: libgtk-3-dev
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_36
+          debug: ${{ env.DEBUG }}
+
+  regression_37:
+    runs-on: ubuntu-latest
+    name: "Install with reported package deps not installed (regression issue #37)."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: libosmesa6-dev libgl1-mesa-dev python3-tk pandoc git-restore-mtime
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_37
+          debug: ${{ env.DEBUG }}
+
+  regression_72_1:
+    runs-on: ubuntu-latest
+    name: "Cache Java CA certs package v1 (regression issue #72)."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: openjdk-11-jre
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_72
+          debug: ${{ env.DEBUG }}
+
+  regression_72_2:
+    runs-on: ubuntu-latest
+    name: "Cache Java CA certs package v2 (regression issue #72)."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: default-jre
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_72
+          debug: ${{ env.DEBUG }}
+
+  regression_76:
+    runs-on: ubuntu-latest
+    name: "Cache empty archive (regression issue #76)."
+    steps:
+      - uses: actions/checkout@v4
+      - run: |
+          sudo wget -O- https://apt.repos.intel.com/intel-gpg-keys/GPG-PUB-KEY-INTEL-SW-PRODUCTS.PUB | gpg --dearmor | sudo tee /usr/share/keyrings/oneapi-archive-keyring.gpg > /dev/null;
+          echo "deb [signed-by=/usr/share/keyrings/oneapi-archive-keyring.gpg] https://apt.repos.intel.com/oneapi all main" | sudo tee /etc/apt/sources.list.d/oneAPI.list;
+          sudo apt-get -qq update;
+          sudo apt-get install -y intel-oneapi-runtime-libs intel-oneapi-runtime-opencl;
+          sudo apt-get install -y opencl-headers ocl-icd-opencl-dev;
+          sudo apt-get install -y libsundials-dev;
+      - uses: ./
+        with:
+          packages: intel-oneapi-runtime-libs
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_76
+          debug: ${{ env.DEBUG }}
+
+  regression_79:
+    runs-on: ubuntu-latest
+    name: "Tar error with libboost-dev (regression issue #79)."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: libboost-dev
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_79
+          debug: ${{ env.DEBUG }}
+
+  regression_81:
+    runs-on: ubuntu-latest
+    name: "Tar error with alsa-ucm-conf (regression issue #81)."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: libasound2 libatk-bridge2.0-0 libatk1.0-0 libatspi2.0-0 libcups2 libdrm2 libgbm1 libnspr4 libnss3 libxcomposite1 libxdamage1 libxfixes3 libxkbcommon0 libxrandr2
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_81
+          debug: ${{ env.DEBUG }}
+
+  regression_84_literal_block_install:
+    runs-on: ubuntu-latest
+    name: "Install multiline package listing - literal block (regression issue #84)."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: >
+            xdot
+            rolldice distro-info-data
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_84_literal_block
+          debug: ${{ env.DEBUG }}
+
+  regression_84_literal_block_restore:
+    needs: regression_84_literal_block_install
+    runs-on: ubuntu-latest
+    name: "Restore multiline package listing - literal block (regression issue #84)."
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: xdot rolldice distro-info-data
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_84_literal_block
+          debug: ${{ env.DEBUG }}
+      - name: Verify
+        if: steps.execute.outputs.cache-hit != 'true'
+        run: |
+          echo "cache-hit = ${{ steps.execute.outputs.cache-hit }}"
+          exit 1
+        shell: bash
+
+  regression_84_folded_block_install:
+    runs-on: ubuntu-latest
+    name: "Install multiline package listing - folded block (regression issue #84)."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: |
+            xdot \
+            rolldice distro-info-data
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_84_folded_block
+          debug: ${{ env.DEBUG }}
+
+  regression_84_folded_block_restore:
+    needs: regression_84_folded_block_install
+    runs-on: ubuntu-latest
+    name: "Restore multiline package listing - folded block (regression issue #84)."
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: xdot rolldice distro-info-data
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_84_folded_block
+          debug: ${{ env.DEBUG }}
+      - name: Verify
+        if: steps.execute.outputs.cache-hit != 'true'
+        run: |
+          echo "cache-hit = ${{ steps.execute.outputs.cache-hit }}"
+          exit 1
+        shell: bash
+
+  regression_89:
+    runs-on: ubuntu-latest
+    name: "Upload logs artifact name (regression issue #89)."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: libgtk-3-dev:amd64
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_89
+          debug: ${{ env.DEBUG }}
+
+  regression_98:
+    runs-on: ubuntu-latest
+    name: "Install error due to SHELLOPTS override (regression issue #98)."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: git-restore-mtime libgl1-mesa-dev libosmesa6-dev pandoc
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_98
+          debug: ${{ env.DEBUG }}
+
+  regression_106_install:
+    runs-on: ubuntu-latest
+    name: "Stale apt repo - install phase (regression issue #106)."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: libtk8.6
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_106
+          debug: ${{ env.DEBUG }}
+
+  regression_106_restore:
+    needs: regression_106_install
+    runs-on: ubuntu-latest
+    name: "Stale apt repo - restore phase (regression issue #106)."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: libtk8.6
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-regression_106
+          debug: ${{ env.DEBUG }}
+
+  # === Special Cases ===
+
+  multi_arch_cache_key:
+    runs-on: ubuntu-latest
+    name: "Cache packages with multi-arch cache key."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: libfuse2
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-multi_arch_cache_key
+          debug: ${{ env.DEBUG }}
+
+  virtual_package:
+    runs-on: ubuntu-latest
+    name: "Cache virtual package."
+    steps:
+      - uses: actions/checkout@v4
+      - uses: ./
+        with:
+          packages: libvips
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-virtual_package
+          debug: ${{ env.DEBUG }}

From 5bddecf9cd60475414d9df410cfed6aa34b23e2a Mon Sep 17 00:00:00 2001
From: Rob Taylor <rob.taylor@chipflow.io>
Date: Tue, 10 Mar 2026 18:30:37 +0000
Subject: [PATCH 2/2] Fix dpkg not knowing about packages after cache restore

After cache restore, dpkg had no record of the installed packages because:
1. Only preinst/postinst scripts were cached from /var/lib/dpkg/info/,
   missing .list, .md5sums, .conffiles, and other metadata files
2. The dpkg status database (/var/lib/dpkg/status) was never updated

This meant dpkg -s, apt list --installed, and anything checking package
state would not see the restored packages.

Fix:
- Cache all /var/lib/dpkg/info/<package>.* files (not just install scripts)
- Save each package's dpkg status entry to a .dpkg-status file
- On restore, append status entries to /var/lib/dpkg/status (skipping
  packages that are already registered)

Adds tests verifying dpkg -s reports packages as installed after both
fresh install and cache restore.

Co-developed-by: Claude Code v2.1.58 (claude-opus-4-6)
---
 .github/workflows/action-tests.yml | 47 ++++++++++++++++++++++++++++++
 install_and_cache_pkgs.sh          | 13 +++++++--
 restore_pkgs.sh                    | 29 +++++++++++++++++-
 3 files changed, 85 insertions(+), 4 deletions(-)

diff --git a/.github/workflows/action-tests.yml b/.github/workflows/action-tests.yml
index 2fb8ce3..6e66a94 100644
--- a/.github/workflows/action-tests.yml
+++ b/.github/workflows/action-tests.yml
@@ -473,3 +473,50 @@ jobs:
           packages: libvips
           version: ${{ github.run_id }}-${{ github.run_attempt }}-virtual_package
           debug: ${{ env.DEBUG }}
+
+  # === dpkg Registration Tests ===
+
+  dpkg_status_install:
+    runs-on: ubuntu-latest
+    name: "dpkg knows about packages after install (phase 1)."
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: rolldice
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-dpkg_status
+          debug: ${{ env.DEBUG }}
+      - name: Verify dpkg knows the package
+        run: |
+          dpkg -s rolldice | grep -q 'Status: install ok installed'
+          echo "dpkg reports rolldice as installed after fresh install."
+        shell: bash
+
+  dpkg_status_restore:
+    needs: dpkg_status_install
+    runs-on: ubuntu-latest
+    name: "dpkg knows about packages after cache restore (phase 2)."
+    steps:
+      - uses: actions/checkout@v4
+      - name: Execute
+        id: execute
+        uses: ./
+        with:
+          packages: rolldice
+          version: ${{ github.run_id }}-${{ github.run_attempt }}-dpkg_status
+          debug: ${{ env.DEBUG }}
+      - name: Verify cache hit
+        run: test "${{ steps.execute.outputs.cache-hit }}" = "true"
+        shell: bash
+      - name: Verify dpkg knows the package after cache restore
+        run: |
+          dpkg -s rolldice | grep -q 'Status: install ok installed'
+          echo "dpkg reports rolldice as installed after cache restore."
+        shell: bash
+      - name: Verify the binary works
+        run: |
+          rolldice 2d6
+          echo "rolldice binary works after cache restore."
+        shell: bash
diff --git a/install_and_cache_pkgs.sh b/install_and_cache_pkgs.sh
index 1a544ad..006fda7 100755
--- a/install_and_cache_pkgs.sh
+++ b/install_and_cache_pkgs.sh
@@ -101,11 +101,15 @@ for installed_package in ${installed_packages}; do
     read package_name package_ver < <(get_package_name_ver "${installed_package}")
     log "  * Caching ${package_name} to ${cache_filepath}..."
 
-    # Pipe all package files (no folders), including symlinks, their targets, and installation control data to Tar.
+    # Pipe all package files (no folders), including symlinks, their targets,
+    # and all dpkg metadata (info files) to Tar.
     tar -cf "${cache_filepath}" -C / --verbatim-files-from --files-from <(
       { dpkg -L "${package_name}" &&
-        get_install_script_filepath "" "${package_name}" "preinst" &&
-        get_install_script_filepath "" "${package_name}" "postinst" ; } |
+        # Include all dpkg info files for this package (list, md5sums,
+        # conffiles, triggers, preinst, postinst, prerm, postrm, etc.)
+        # so dpkg recognizes the package after cache restore.
+        ls -1 /var/lib/dpkg/info/${package_name}.* 2>/dev/null &&
+        ls -1 /var/lib/dpkg/info/${package_name}:*.* 2>/dev/null ; } |
       while IFS= read -r f; do
         if test -f "${f}" -o -L "${f}"; then
           get_tar_relpath "${f}"
@@ -119,6 +123,9 @@ for installed_package in ${installed_packages}; do
       done
     )
 
+    # Save the dpkg status entry so we can register the package on restore.
+    dpkg -s "${package_name}" > "${cache_dir}/${installed_package}.dpkg-status" 2>/dev/null || true
+
     log "    done (compressed size $(du -h "${cache_filepath}" | cut -f1))."
   fi
 
diff --git a/restore_pkgs.sh b/restore_pkgs.sh
index 4556265..ef9418d 100755
--- a/restore_pkgs.sh
+++ b/restore_pkgs.sh
@@ -50,7 +50,7 @@ for cached_filepath in ${cached_filepaths}; do
   sudo tar -xf "${cached_filepath}" -C "${cache_restore_root}" > /dev/null
   log "  done"
 
-  # Execute install scripts if available.    
+  # Execute install scripts if available.
   if test ${execute_install_scripts} == "true"; then
     # May have to add more handling for extracting pre-install script before extracting all files.
     # Keeping it simple for now.
@@ -59,3 +59,30 @@ for cached_filepath in ${cached_filepaths}; do
   fi
 done
 log "done"
+
+log_empty_line
+
+# Register packages with dpkg so they appear as installed.
+# The tar extraction restores dpkg info files (list, md5sums, etc.) but the
+# main status database (/var/lib/dpkg/status) also needs updating.
+dpkg_status_dir="${cache_dir}"
+status_files=$(ls -1 "${dpkg_status_dir}"/*.dpkg-status 2>/dev/null || true)
+if test -n "${status_files}"; then
+  log "Registering restored packages with dpkg..."
+  for status_file in ${status_files}; do
+    pkg_name=$(head -1 "${status_file}" | sed 's/^Package: //')
+    # Skip if dpkg already knows about this package (e.g., it was pre-installed).
+    if dpkg -s "${pkg_name}" > /dev/null 2>&1; then
+      existing_status=$(dpkg -s "${pkg_name}" 2>/dev/null | grep '^Status:' | head -1)
+      if echo "${existing_status}" | grep -q 'install ok installed'; then
+        log "- ${pkg_name} already registered, skipping."
+        continue
+      fi
+    fi
+    # Append the status entry (with blank line separator) to the dpkg database.
+    echo "" | sudo tee -a "${cache_restore_root}var/lib/dpkg/status" > /dev/null
+    cat "${status_file}" | sudo tee -a "${cache_restore_root}var/lib/dpkg/status" > /dev/null
+    log "- ${pkg_name} registered."
+  done
+  log "done"
+fi