slackrepo_setup: build in .new and swap; sbshadow --yesHEADmaster

A failed clone no longer leaves the VM without a tree: the new tree is
built in $REPO.new and swapped in only when clone and subtree adds
succeed. sbshadow runs with --yes, since sb-builder runs this script as
a job with no stdin and the bare prompt would read EOF as "no". The old
tree is deleted once shadowing succeeds and kept as $REPO.old if it
fails. SBO_REPO overrides the path, as in sbshadow.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

3 files changed, 37 insertions, 24 deletions

diff --git a/AGENTS.md b/AGENTS.md
index 5bf3ac3..ffe1953 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -65,8 +65,10 @@ the config with `/usr/local/bin/` rewritten to a stub dir (stub `sb-publish`,
 ./slackrepo_setup_SBo-danix.sh
 ```
 
-Destructive: `rm -rf`s `$REPO` on every run to start clean, then re-clones upstream. Interactive
-`read` prompt inside `sbshadow` is the only confirmation (declining exits 0, run continues).
+Destructive: builds a fresh tree in `$REPO.new`, swaps it in (old tree to `$REPO.old`), runs
+`sbshadow --yes`, then deletes `$REPO.old`. A failed clone or subtree add leaves `$REPO` untouched;
+a failed `sbshadow` keeps `$REPO.old` for a manual rollback. Non-interactive: sb-builder runs it
+as a job with no stdin. `SBO_REPO` overrides the path, for trying it on a throwaway repo.
 
 ## Architecture
 
diff --git a/README.md b/README.md
index 04e525e..06a8b45 100644
--- a/README.md
+++ b/README.md
@@ -15,9 +15,11 @@ upstream tree), so the overlay version wins.
 
 ## Files
 
-- `slackrepo_setup_SBo-danix.sh`: full rebuild. Wipes the repo, clones upstream,
-  adds the subtrees, then runs `sbshadow`. **Destructive**: `rm -rf`s the repo
-  on every run.
+- `slackrepo_setup_SBo-danix.sh`: full rebuild. Clones upstream and adds the
+  subtrees in `$REPO.new`, swaps it in, then runs `sbshadow --yes`.
+  **Destructive**: the old tree is deleted once shadowing succeeds; a failed
+  clone leaves it untouched, a failed `sbshadow` leaves it as `$REPO.old`.
+  sb-builder runs it as the `rebuild-tree` job.
 - `sbshadow`: reconciles shadowing both ways. Shadows upstream packages now
   carried in an overlay, and restores (unshadows) upstream packages no longer
   carried, from the pristine `current` branch. Asks once before changing
diff --git a/slackrepo_setup_SBo-danix.sh b/slackrepo_setup_SBo-danix.sh
index be2b1dd..f54e947 100644
--- a/slackrepo_setup_SBo-danix.sh
+++ b/slackrepo_setup_SBo-danix.sh
@@ -5,45 +5,54 @@
 # under the terms of the GNU General Public License version 2 as published
 # by the Free Software Foundation. See the LICENSE file for details.
 
+# Rebuild the SBo-danix tree: fresh clone of upstream plus the personal and
+# pentesting subtrees, built beside the live tree and swapped in, then shadowed.
+# Run by sb-builder as the rebuild-tree job (no stdin).
+# SBO_REPO overrides the repo path (used to test against a throwaway repo).
 
 set -euo pipefail
 
-REPO="/var/lib/sbopkg/SBo-danix"
+REPO="${SBO_REPO:-/var/lib/sbopkg/SBo-danix}"
+NEW="$REPO.new"
+OLD="$REPO.old"
+export SBO_REPO="$REPO"  # sbshadow reads the same override
 
 # ── safety guard ──────────────────────────────────────────────────────────────
-if [[ -z "$REPO" ]]; then
-  echo "ERROR: REPO is unset or empty. Aborting." >&2
+if [[ -z "$REPO" || "$REPO" == / ]]; then
+  echo "ERROR: REPO is unset, empty or /. Aborting." >&2
   exit 1
 fi
 
-# ── clean slate ───────────────────────────────────────────────────────────────
-if [[ -d "$REPO" ]]; then
-  echo "Removing existing repo at $REPO..."
-  rm -rf "$REPO"
-fi
-
-# ── clone and branch ──────────────────────────────────────────────────────────
-echo "Cloning upstream SBo repository..."
-git clone https://github.com/Ponce/slackbuilds.git "$REPO" || {
-  echo "ERROR: git clone failed. Aborting." >&2
-  exit 1
-}
+# ── build the new tree beside the live one ────────────────────────────────────
+# A failure here leaves $REPO untouched.
+rm -rf "$NEW"
+echo "Cloning upstream SBo repository into $NEW..."
+git clone https://github.com/Ponce/slackbuilds.git "$NEW"
 
-cd "$REPO"
+cd "$NEW"
 git checkout current
 git checkout -b danix-current
 
-# ── add subtrees ──────────────────────────────────────────────────────────────
 echo "Adding personal subtrees..."
 git remote add my-slackbuilds https://github.com/danixland/my-slackbuilds.git
 git remote add my-pentesting  https://github.com/danixland/Slackware-Pentesting-Suite.git
 
 git subtree add --prefix=personal   my-slackbuilds main --squash
 git subtree add --prefix=pentesting my-pentesting  main --squash
+cd /
+
+# ── swap ──────────────────────────────────────────────────────────────────────
+rm -rf "$OLD"
+if [[ -d "$REPO" ]]; then
+  mv "$REPO" "$OLD"
+fi
+mv "$NEW" "$REPO"
 
 # ── shadow upstream packages + regen hintfiles (sbshadow owns both) ──────────
-# sbshadow must be on PATH (deployed next to this script on the build system).
-sbshadow
+# --yes: as a job stdin is /dev/null, so a prompt would read "no".
+# If it fails, set -e keeps $OLD for a manual rollback (mv it back).
+sbshadow --yes
 
+rm -rf "$OLD"
 echo
 echo "Done. Repository ready at $REPO"