Fix grub-install BOOT_PATH, validate grub-mkconfig timeout, add fat_tool sync

Fix BOOT_PATH logic in grub-install: non-removable installs now use
EFI/${BOOTLOADER_ID} per UEFI spec instead of always EFI/BOOT.
Add timeout validation to grub-mkconfig (must be non-negative integer).
Add sync() method to fat_tool.py and call os.fsync after cp_in to
ensure data reaches disk. Fix misleading block-device error message.

local/scripts/fat_tool.py

@@ -105,6 +105,10 @@ class Fat32:
             self.f.seek(self.fat_start + i * self.fat_size * self.bytes_per_sector)
             self.f.write(self.fat)
 
+    def sync(self):
+        self.f.flush()
+        os.fsync(self.f.fileno())
+
     def _cluster_offset(self, cluster):
         if not 2 <= cluster <= self.max_cluster:
             raise RuntimeError(f"FAT32: invalid cluster {cluster}")
@@ -570,6 +574,7 @@ class Fat32:
             else:
                 self._add_dir_entry(parent_cluster, file_name, first_cluster, False, len(data))
             self.f.flush()
+            os.fsync(self.f.fileno())
         except Exception:
             if clusters:
                 self._free_cluster_chain(clusters[0])

local/scripts/grub-install

@@ -241,9 +241,10 @@ if [ -n "$DISK_IMAGE" ]; then
     ESP_OFFSET=$((2048 * 512))
 
     # Write GRUB to ESP
-    BOOT_PATH="EFI/BOOT"
+    if [ "$REMOVABLE" -eq 1 ]; then
-    if [ "$REMOVABLE" -eq 0 ] && [ -n "$BOOTLOADER_ID" ]; then
         BOOT_PATH="EFI/BOOT"
+    else
+        BOOT_PATH="EFI/${BOOTLOADER_ID}"
     fi
 
     "$FAT_TOOL" mkdir "$DISK_IMAGE" "$ESP_OFFSET" "EFI" 2>/dev/null || true
@@ -265,9 +266,10 @@ fi
 
 # Mode 2: Full image build via Red Bear installer (INSTALL_DEVICE given)
 if [ -n "$INSTALL_DEVICE" ]; then
-    echo "$PROG: installing to $INSTALL_DEVICE via Red Bear installer..." >&2
+    echo "$PROG: block device installation is not supported by this wrapper." >&2
-    echo "$PROG: for Red Bear OS, use: make all CONFIG_NAME=redbear-full-grub" >&2
+    echo "$PROG: For Red Bear OS, use one of:" >&2
-    echo "$PROG: or: redox_installer -c redbear-full-grub.toml $INSTALL_DEVICE" >&2
+    echo "$PROG:   make all CONFIG_NAME=redbear-full-grub" >&2
+    echo "$PROG:   redox_installer -c redbear-full-grub.toml $INSTALL_DEVICE" >&2
     exit 1
 fi
 

local/scripts/grub-mkconfig

@@ -85,6 +85,10 @@ while [ $# -gt 0 ]; do
     esac
 done
 
+case "$TIMEOUT" in
+    ''|*[!0-9]*) echo "$PROG: invalid timeout '$TIMEOUT' (must be a non-negative integer)" >&2; exit 1;;
+esac
+
 generate_config() {
     cat <<GRUBCFG
 # Generated by $PROG — $(date -Iseconds 2>/dev/null || date)