Remove the release directory a failed deploy leaves behind

A deploy that died after mkdir -- a broken build, a missing lock file, a
health check that never went green -- left its half-finished release in
releases/. That is not just disk: it is the newest directory there, so the
KEEP=3 rotation of the next successful deploy counted it among the three to
keep and dropped a working release instead, thinning out exactly the rollback
targets the runbook tells you to use.

The release directory is now armed for cleanup the moment it is created and
disarmed once the release is live and healthy, with the removal done by the
same EXIT trap that drops the unpacked archive -- so it covers every way out:
fatal, a command failing under set -e, an aborted build. The one case left
alone is a release the swap did reach and that `current` still points at, i.e.
a first-ever deploy with nothing to roll back to: removing that would leave a
dangling symlink behind instead.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

deploy/bin/exo-deploy

@@ -91,7 +91,21 @@ fi
 # ------------------------------------------------------- archive, if any
 
 STAGE=""
-cleanup() { if [[ -n $STAGE ]]; then rm -rf "$STAGE"; fi; }
+PENDING_REL=""   # release being built; cleared once it is live and healthy
+PENDING_LINK=""  # its app's `current` symlink
+
+# A release that never went live is not just wasted disk: it is the newest
+# directory in releases/, so the KEEP rotation below would keep it and drop a
+# working release instead — the very one the rollback in the runbook needs.
+# Anything the swap did reach is left alone, dangling symlinks included.
+cleanup() {
+  if [[ -n $STAGE ]]; then rm -rf "$STAGE"; fi
+  if [[ -n $PENDING_REL && -d $PENDING_REL ]] &&
+     [[ "$(readlink -f "$PENDING_LINK" 2>/dev/null || true)" != "$PENDING_REL" ]]; then
+    echo "==> removing incomplete release $PENDING_REL"
+    rm -rf "$PENDING_REL"
+  fi
+}
 trap cleanup EXIT
 
 # Shallowest <app>/ directory in the archive that holds a package.json, so both
@@ -168,6 +182,8 @@ deploy_app() {
   [[ -n $PORT ]] || fatal "PORT not set in $ENVFILE"
 
   mkdir -p "$REL"
+  PENDING_REL="$REL"
+  PENDING_LINK="$BASE/current"
 
   if [[ -n $ZIP ]]; then
     src="$(app_src "$APP")" || fatal "$ZIP: no $APP/ directory with a package.json inside"
@@ -185,7 +201,7 @@ deploy_app() {
 
     echo "==> extracting $APP/ into $REL"
     git -C "$BASE/repo" archive "$REF" "$APP" | tar -x -C "$REL" --strip-components=1
-    [[ -f $REL/package.json ]] || { rm -rf "$REL"; fatal "$APP/ not found at $REF"; }
+    [[ -f $REL/package.json ]] || fatal "$APP/ not found at $REF"
     desc="git $REF $(git -C "$BASE/repo" rev-parse --short "$REF")"
   fi
 
@@ -251,6 +267,10 @@ deploy_app() {
   grep -q '"ok":true' <<<"$HEALTH" || fatal "health not ok"
   grep -q '"amo":true' <<<"$HEALTH" || echo "    WARNING: amo=false — /api/leads/* will return 503. Check AMO_* in $ENVFILE."
 
+  # Live and healthy: from here on it is a release like any other.
+  PENDING_REL=""
+  PENDING_LINK=""
+
   # Prune old releases, never the live one.
   CURRENT="$(readlink -f "$BASE/current")"
   ls -1dt "$BASE"/releases/*/ 2>/dev/null | tail -n "+$((KEEP+1))" | while read -r old; do