Add PKG_CACHE config var (empty = disabled)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

2 files changed, 12 insertions, 0 deletions

diff --git a/config.example b/config.example
index 88cc264..a524400 100644
--- a/config.example
+++ b/config.example
@@ -31,5 +31,10 @@ CHROOT_LOCATION="/tmp"
 # Where persistent logs are written (outside the overlay, survives teardown).
 LOG_ROOT="/var/log/sbo-batch-test"
 
+# Persistent package cache. Local disk, survives across runs. Built dependency
+# packages are stored here and reused when their version is unchanged. Wiped
+# automatically when the base is patched. Leave empty to disable caching.
+PKG_CACHE="/var/cache/sbo-batch-test"
+
 # Slackware version, used for the mirror ChangeLog / patches path.
 VERSION="15.0"
diff --git a/sbo-batch-test b/sbo-batch-test
index 0c39ed2..a9e3d14 100755
--- a/sbo-batch-test
+++ b/sbo-batch-test
@@ -37,6 +37,13 @@ LOCAL_MIRROR_15=""
 SBO_TREE_ROOTS=()
 CHROOT_LOCATION="/tmp"
 LOG_ROOT="/var/log/sbo-batch-test"
+
+# Persistent package cache (local disk). Built dependency packages are stored
+# here and reused across runs while their version is unchanged. Empty disables
+# the cache (every package builds fresh). Wiped automatically when the base is
+# patched. Layout mirrors the SBo tree: <cat>/<prog>/<prog>-<ver>-...txz
+PKG_CACHE=""
+
 VERSION="15.0"
 
 # Source the external config if present. Not an error here if missing (keeps the