diff --git a/.gitea/workflows/debian.yml b/.gitea/workflows/debian.yml
index 3104b2b..1324513 100644
--- a/.gitea/workflows/debian.yml
+++ b/.gitea/workflows/debian.yml
@@ -22,9 +22,7 @@ jobs:
           set -euo pipefail
           for script in packaging/*.sh packaging/overlays/v1/*.sh; do bash -n "$script"; done
           mkdir -p "$RUNNER_TEMP/debs"
-          bash packaging/run.sh "$RUNNER_TEMP/debs"
-          docker run --rm --mount "type=bind,src=$PWD/packaging,dst=/checks/packaging,readonly" \
-            -w /checks g15-packaging shellcheck packaging/*.sh packaging/overlays/v1/*.sh
+          bash packaging/ci.sh "$RUNNER_TEMP/debs"
           test -z "$(git submodule foreach --quiet --recursive 'git status --porcelain')"
       - name: Upload verified binaries and standalone sources
         uses: https://github.com/actions/upload-artifact@ff15f0306b3f739f7b6fd43fb5d26cd321bd4de5 # v3 (Gitea artifact protocol)
diff --git a/README.md b/README.md
index 4fd92af..def4a32 100644
--- a/README.md
+++ b/README.md
@@ -25,8 +25,9 @@ Use the verified Debian source artifacts instead.
 
 Gitea Actions builds all five projects on pushes to `main` and manual dispatch.
 Successful runs provide the `debian13-amd64` artifact, including binaries,
-standalone sources and `SHA256SUMS`. An `ubuntu-latest` runner with local Docker
-and matching workspace mount paths is required; see `packaging/NOTES.md`.
+standalone sources and `SHA256SUMS`. An `ubuntu-latest` runner with Docker
+access is required; copy-based CI also supports sibling Docker daemons.
+See `packaging/NOTES.md`.
 
 **Safety limitation:** legacy macro memory/configuration handling has known
 preexisting defects. Compatibility overlays do not repair the macro engine.
diff --git a/packaging/NOTES.md b/packaging/NOTES.md
index b145baf..502beff 100644
--- a/packaging/NOTES.md
+++ b/packaging/NOTES.md
@@ -78,8 +78,11 @@ and udev installation, macro help/version and purge cleanup. Source rebuilds
 install newly rebuilt dependencies, not binaries from the first build.
 
 Gitea CI (`.gitea/workflows/debian.yml`) builds on every push to `main` and
-manual dispatch, using an `ubuntu-latest` runner with local Docker Engine.
-The runner must expose the same workspace paths to Docker for read-only mounts.
+manual dispatch, using an `ubuntu-latest` runner with Docker Engine access.
+`ci.sh` copies only the build-input allowlist into disposable containers instead
+of bind-mounting runner paths, supporting containerized runners with sibling
+Docker daemons. The standalone rebuild receives only artifacts and its script.
+Containers are removed on exit; their exit codes are explicitly checked.
 It uploads `debian13-amd64` artifacts using the Gitea-compatible v3 protocol;
 download the artifact from the successful run and check `SHA256SUMS`.
 Gitea does not run the GitHub CLI release job or publish release assets.
diff --git a/packaging/ci.sh b/packaging/ci.sh
new file mode 100644
index 0000000..e08b543
--- /dev/null
+++ b/packaging/ci.sh
@@ -0,0 +1,30 @@
+#!/bin/bash
+# Copy-based isolation for containerized runners using a sibling Docker daemon.
+set -euo pipefail
+root=$(cd -- "$(dirname -- "$0")/.." && pwd)
+out=$(realpath "${1:?empty output directory outside checkout required}")
+[[ -d $out && -z $(find "$out" -mindepth 1 -print -quit) ]] || exit 1
+case $out in "$root"|"$root"/*) exit 1 ;; esac
+[[ -d $root/.git ]] || exit 1
+image=${G15_BUILD_IMAGE:-g15-packaging}
+build=''
+rebuild=''
+cleanup() {
+    [[ -z $build ]] || docker rm -f "$build" >/dev/null
+    [[ -z $rebuild ]] || docker rm -f "$rebuild" >/dev/null
+}
+trap cleanup EXIT
+docker build -t "$image" -f "$root/packaging/Dockerfile" "$root/packaging"
+build=$(docker create "$image" bash -c 'mkdir /out && shellcheck packaging/*.sh packaging/overlays/v1/*.sh && bash packaging/container-build.sh')
+# Explicit allowlist: never copy editor settings, credentials or unrelated files.
+for path in .git .gitmodules packaging libg15 libg15render g15daemon g15macro g15stats; do
+    docker cp "$root/$path" "$build:/work/$path"
+done
+docker start -a "$build"
+[[ $(docker inspect -f '{{.State.ExitCode}}' "$build") == 0 ]]
+docker cp "$build:/out/." "$out/"
+rebuild=$(docker create "$image" bash -c 'apt-get update && bash /rebuild.sh /out')
+docker cp "$out" "$rebuild:/out"
+docker cp "$root/packaging/rebuild.sh" "$rebuild:/rebuild.sh"
+docker start -a "$rebuild"
+[[ $(docker inspect -f '{{.State.ExitCode}}' "$rebuild") == 0 ]]
\ No newline at end of file