fix(status-bar): address Copilot review on /battery

- TUI /battery matches the CLI surface: adds `status` (live reading via
  system.battery), and the help/usage strings now consistently read
  [on|off|status].
- batteryLabel() renders `--` for an unknown percent so a null can never
  surface as "null%" even without the showBattery guard.
- Move the system.battery RPC out of the config section into
  "Methods: tools & system" where system.* RPCs belong.

tui_gateway/server.py

@@ -11319,31 +11319,6 @@ def _(rid, params: dict) -> dict:
 # ── Methods: config ──────────────────────────────────────────────────
 
 
-@method("system.battery")
-def _(rid, params: dict) -> dict:
-    """Return the host battery status for the status-bar read-out.
-
-    Always resolves with a payload; ``available: false`` means there is no
-    battery (desktop/server/VM) or the read failed. The TUI only polls this
-    while the battery indicator is enabled.
-    """
-    try:
-        from agent.battery import battery_category, read_battery
-
-        batt = read_battery()
-        return _ok(
-            rid,
-            {
-                "available": batt.available,
-                "percent": batt.percent,
-                "plugged": batt.plugged,
-                "category": battery_category(batt),
-            },
-        )
-    except Exception:
-        return _ok(rid, {"available": False, "percent": None, "plugged": None, "category": "dim"})
-
-
 @method("config.set")
 def _(rid, params: dict) -> dict:
     key, value = params.get("key", ""), params.get("value", "")
@@ -12773,6 +12748,31 @@ def _(rid, params: dict) -> dict:
 # ── Methods: tools & system ──────────────────────────────────────────
 
 
+@method("system.battery")
+def _(rid, params: dict) -> dict:
+    """Return the host battery status for the status-bar read-out.
+
+    Always resolves with a payload; ``available: false`` means there is no
+    battery (desktop/server/VM) or the read failed. The TUI only polls this
+    while the battery indicator is enabled.
+    """
+    try:
+        from agent.battery import battery_category, read_battery
+
+        batt = read_battery()
+        return _ok(
+            rid,
+            {
+                "available": batt.available,
+                "percent": batt.percent,
+                "plugged": batt.plugged,
+                "category": battery_category(batt),
+            },
+        )
+    except Exception:
+        return _ok(rid, {"available": False, "percent": None, "plugged": None, "category": "dim"})
+
+
 @method("process.stop")
 def _(rid, params: dict) -> dict:
     try:

ui-tui/src/app/slash/commands/core.ts

@@ -11,7 +11,8 @@ import type {
   SessionStatusResponse,
   SessionSteerResponse,
   SessionTitleResponse,
-  SessionUndoResponse
+  SessionUndoResponse,
+  SystemBatteryResponse
 } from '../../../gatewayTypes.js'
 import { writeClipboardText } from '../../../lib/clipboard.js'
 import { writeOsc52Clipboard } from '../../../lib/osc52.js'
@@ -580,13 +581,35 @@ export const coreCommands: SlashCommand[] = [
   },
 
   {
-    help: 'toggle a color-coded battery indicator in the status bar [on|off]',
+    help: 'toggle a color-coded battery indicator in the status bar [on|off|status]',
     name: 'battery',
     run: (arg, ctx) => {
+      const mode = arg.trim().toLowerCase()
+
+      // `/battery status` reports the current setting plus a live reading,
+      // matching the CLI surface. Fetch on demand so it works even while the
+      // indicator (and its poller) is off.
+      if (mode === 'status' || mode === 'show') {
+        const state = ctx.ui.battery ? 'on' : 'off'
+
+        ctx.gateway
+          .rpc<SystemBatteryResponse>('system.battery', {})
+          .then(r => {
+            if (r?.available && typeof r.percent === 'number') {
+              ctx.transcript.sys(`battery indicator ${state} — currently ${r.plugged ? '⚡' : '🔋'} ${r.percent}%`)
+            } else {
+              ctx.transcript.sys(`battery indicator ${state} — no battery detected on this machine`)
+            }
+          })
+          .catch(() => ctx.transcript.sys(`battery indicator ${state}`))
+
+        return
+      }
+
       const next = flagFromArg(arg, ctx.ui.battery)
 
       if (next === null) {
-        return ctx.transcript.sys('usage: /battery [on|off|toggle]')
+        return ctx.transcript.sys('usage: /battery [on|off|status]')
       }
 
       patchUiState({ battery: next, ...(next ? {} : { batteryStatus: null }) })

ui-tui/src/components/appChrome.tsx

@@ -209,8 +209,9 @@ function batteryColor(info: BatteryInfo, t: Theme): string {
 }
 
 // Compact battery label: a bolt while charging, else a battery glyph.
+// Renders `--` for an unknown percent so a null can never surface as "null%".
 function batteryLabel(info: BatteryInfo): string {
-  return `${info.plugged ? '⚡' : '🔋'} ${info.percent}%`
+  return `${info.plugged ? '⚡' : '🔋'} ${info.percent ?? '--'}%`
 }
 
 // Colour a credits notice by its level. The notice TEXT already carries its