fix: fence reconciliation admission race

scripts/windows/test-host

@@ -540,7 +540,22 @@ case "$action" in
                 attempt=$((attempt + 1))
                 sleep 1
             done
-            [ "$(state)" = poweroff ] || fail "guest did not power off before reset"
+            # This is the exact named disposable fixture, with the matching
+            # run lease. Reset is its isolation boundary, not a graceful-stop
+            # diagnostic command: after a bounded ACPI attempt, discard only
+            # this guest's state so snapshot restore cannot strand the lane.
+            if [ "$(state)" != poweroff ]; then
+                printf 'reset: ACPI shutdown timed out; forcing disposable VM poweroff\n' >&2
+                VBoxManage controlvm "$vm" poweroff >/dev/null
+                attempt=0
+                while [ "$attempt" -lt 30 ]; do
+                    [ "$(state)" = poweroff ] && break
+                    attempt=$((attempt + 1))
+                    sleep 1
+                done
+                [ "$(state)" = poweroff ] || fail "guest did not power off after forced reset"
+                printf 'reset-force-poweroff vm=%s\n' "$vm"
+            fi
         fi
         VBoxManage snapshot "$vm" restore "$snapshot" >/dev/null
         assert_identity
@@ -580,7 +595,9 @@ accelerated_stage() {
         printf 'stage: accelerated publish directory unavailable\n' >&2
         return 1
     }
-    stage_http_dir=$(mktemp -d "${TMPDIR:-/tmp}/rvbox-http-stage.XXXXXX")
+    # Keep all disposable test bytes inside the owning run directory; never
+    # consume global /tmp, which may belong to a different test or user.
+    stage_http_dir=$(mktemp -d "$run_root/.accelerated-stage.XXXXXX")
     stage_http_xz=$stage_http_dir/rvbox.exe.xz
     xz -T0 -3 -c "$bundle/rvbox.exe" >"$stage_http_xz"
     stage_http_hash=$(sha256sum "$stage_http_xz" | awk '{print $1}')
@@ -615,7 +632,7 @@ copy_stage_file() {
     target_name=$2
     copy_attempt=1
     while [ "$copy_attempt" -le 4 ]; do
-        if scp -q "$source_file" "$RVBOX_TEST_VBOX_HOST:$host_stage/$target_name"; then
+        if scp -q -o BatchMode=yes -o ConnectTimeout=10 -o ServerAliveInterval=10 -o ServerAliveCountMax=2 "$source_file" "$RVBOX_TEST_VBOX_HOST:$host_stage/$target_name"; then
             return 0
         fi
         copy_attempt=$((copy_attempt + 1))