fix: shellcheck in the bundle, and the docs for the BIOS checks

- Rename a variable in lib/bios.sh that clashed with lib/state.sh's array in the bundle.
- README, AGENTS.md and CHANGELOG.md for the greyed-out item, the device check and the aligned warning box.

AGENTS.md

@@ -135,6 +135,11 @@ gamescope and the Plasma desktop. Primary target: the Valve Steam Machine
 - `bios` is an *action* (`ACTIONS` in `lib/menu.sh`), not an on/off
   component: never preselected (not even on a first run), never re-applied
   by `a`, not listed in the state overview, and `bios_status` is always off.
+  Only selectable when Valve's version differs from the installed one
+  (`component_selectable`, greyed out otherwise). Download, SHA-256 and the
+  fwupd device check (`get-details --json`: no `UpdateError`) come before the
+  warnings. The warning box uses `█` for its frame: Konsole draws a long
+  coloured row of `#` narrower, so the right edge wouldn't line up.
   Keep both confirmations (y/N, then typing `UPDATE`) and the warnings; the
   firmware comes from the newest `holo-X.Y` repo (`.files` db names the
   `.cab`, `.db` gives the SHA-256), and fwupd itself refuses non-Fremont
@@ -144,6 +149,11 @@ gamescope and the Plasma desktop. Primary target: the Valve Steam Machine
 
 ## Checking changes
 
+The bundle puts every module in one file, so shellcheck sees all their
+`local` variables together: don't reuse a name another module uses as an
+array (e.g. `g` in `lib/state.sh`), or CI's shellcheck on the bundle fails.
+
+
 There is no test suite. At minimum:
 
 ```bash

CHANGELOG.md

@@ -56,12 +56,21 @@ Machine LED driver works on every installed kernel and survives kernel updates.
   - When a new version is released, the `latest` tag and release move to it
     (bundle replaced), so the older `.../releases/download/latest/...` URL
     also always gives the newest version.
-- **feat: Opt-in BIOS update for the Steam Machine**
+- `2f9b2a5` **feat: Opt-in BIOS update for the Steam Machine**
   - New menu item (Steam Machine only, never ticked by default) showing the
     current BIOS version and the newest from Valve's `fremont-hw-support`.
   - Two large warnings and two confirmations (y/N, then typing `UPDATE`),
     checksum-verified download, installed with fwupd; the wizard then offers
     the restart that writes it, with a warning to keep the power on.
+- `40c9ee6` **fix: BIOS update only when newer, device check first, aligned warnings**
+  - The item is greyed out and can't be ticked unless Valve has a newer BIOS.
+  - Before any warning: SHA-256 of Valve's package, then fwupd confirms the
+    firmware fits this machine's hardware; otherwise it stops.
+  - Warning box drawn with a solid red frame whose edges line up, and the
+    menu's "Now" column aligned.
+- **fix: shellcheck in the bundle, and the docs for the BIOS checks**
+  - A variable name in `lib/bios.sh` clashed with `lib/state.sh` in the bundle
+    (CI's shellcheck would fail); README, AGENTS.md and this changelog updated.
 
 ## 0.6.2 - 2026-09-23
 

README.md

@@ -286,10 +286,13 @@ journalctl --user -b | grep -i led
 **BIOS updates** (opt-in, never ticked by default). On a Steam Machine the menu
 has an **Update BIOS** item that shows the current BIOS version and the newest
 one Valve ships (`F7F0108.cab` in its `fremont-hw-support` package, looked up
-on Valve's SteamOS mirror). Ticking it shows a large warning, asks for
-confirmation, shows the warning again and only continues when you type
-`UPDATE`. It then downloads the package (checksum verified) and hands the
-firmware to fwupd; the BIOS is written during the next restart.
+on Valve's SteamOS mirror). It can only be ticked when Valve has a newer BIOS
+than the one installed; otherwise it's greyed out. Before asking anything it
+downloads the package and checks it: the SHA-256 from Valve's repository
+proves it's Valve's file, and fwupd confirms the firmware is for this very
+machine (it compares the firmware's hardware IDs with the device). Only then
+it shows a large warning and asks for confirmation, shows the warning again
+and continues when you type `UPDATE`; the BIOS is written during the next restart.
 
 **At your own risk:** a failed or interrupted BIOS update can leave the machine
 unable to start. Keep it on mains power, and never turn off the power, unplug

lib/bios.sh

@@ -143,12 +143,12 @@ bios_enable() {
     fi
     ok "fwupd confirms BIOS $BIOS_NEWEST is firmware for this machine."
 
-    local g="$c_green$c_bold" b="$c_bold" n="$c_reset"
+    local yes="$c_green$c_bold" b="$c_bold" n="$c_reset"
     bios_disclaimer "WARNING: BIOS UPDATE - ENTIRELY AT YOUR OWN RISK" \
         "Current BIOS: ${b}$current${n}" \
         "New BIOS:     ${b}$BIOS_NEWEST${n}" \
-        "Checksum:     ${g}OK${n} (Valve's package)" \
-        "Compatible:   ${g}yes${n} (checked by fwupd)"
+        "Checksum:     ${yes}OK${n} (Valve's package)" \
+        "Compatible:   ${yes}yes${n} (checked by fwupd)"
     if ! ask_yn "Do you understand the risks and want to continue?" n; then
         info "BIOS update cancelled; nothing was changed."; rm -rf "$tmp"; return 0
     fi