docs: sync service.luau in plan with review fixes

docs/superpowers/plans/2026-08-31-headsetcontrol-plugin.md

@@ -464,7 +464,7 @@ local function publishCaps(info)
   if info == nil then
     noctalia.state.set("caps", {})
     noctalia.state.set("equalizerPresets", 0)
-    noctalia.state.set("device", nil)
+    noctalia.state.set("error", "no_caps")
     return
   end
   noctalia.state.set("caps", info.caps or {})
@@ -474,28 +474,34 @@ local function publishCaps(info)
     product = info.product,
     vendor = info.vendor,
   })
+  noctalia.state.set("error", "")
 end
 
 local function handleStatus(status)
   if status == nil then
+    local err = noctalia.state.get("error")
+    if err == "no_binary" then
+      return
+    end
     noctalia.state.set("error", "unavailable")
     noctalia.state.set("battery", { status = "BATTERY_UNAVAILABLE", level = -1 })
+    noctalia.state.set("chatmix", 0)
     return
   end
   noctalia.state.set("error", "")
-  local battery = status.battery
+  local battery = status.battery or { status = "BATTERY_UNAVAILABLE", level = -1 }
   noctalia.state.set("battery", battery)
-  noctalia.state.set("chatmix", status.chatmix)
+  noctalia.state.set("chatmix", status.chatmix or 0)
   noctalia.state.set("lastUpdate", noctalia.nowMs())
-  if battery.level and battery.level > 0 and battery.status ~= "BATTERY_UNAVAILABLE" then
-    local low = config().battery_low
+  if battery.level ~= nil and battery.level >= 0 and battery.status ~= "BATTERY_UNAVAILABLE" then
+    local low = config().battery_low or 20
     if battery.level <= low and not warned then
       warned = true
       noctalia.notifyError(
         noctalia.tr("notify.battery_low.title"),
         string.format(noctalia.tr("notify.battery_low.body"), battery.level)
       )
-    elseif battery.level > low + 5 then
+    elseif battery.level > low + 5 or battery.status == "BATTERY_CHARGING" or battery.status == "BATTERY_FULL" then
       warned = false
     end
   end
@@ -508,14 +514,18 @@ end
 local function init()
   local cfg = config()
   hsc.init(cfg)
+  warned = false
   if not hsc.isMock() and not noctalia.commandExists("headsetcontrol") then
     noctalia.state.set("error", "no_binary")
     noctalia.state.set("caps", {})
+    noctalia.state.set("equalizerPresets", 0)
+    noctalia.state.set("battery", { status = "BATTERY_UNAVAILABLE", level = -1 })
+    noctalia.state.set("chatmix", 0)
     noctalia.log("headsetcontrol binary not found; polling disabled")
     return
   end
   hsc.fetchCapabilities(publishCaps)
-  noctalia.setUpdateInterval(cfg.poll_interval * 1000)
+  noctalia.setUpdateInterval((cfg.poll_interval or 60) * 1000)
   poll()
 end
 
@@ -533,18 +543,10 @@ function onIpc(event, _payload)
   end
 end
 
-function onExit(_signal, reason)
-  if reason == "uninstall" or reason == "disable" then
-    noctalia.state.set("error", "")
-    noctalia.state.set("battery", nil)
-    noctalia.state.set("caps", {})
-  end
-end
-
 init()
 ```
 
-> Note: clearing `error` with `""` (not `nil`) because state values should stay within the documented plain-value types; `battery`/`device` are cleared with `nil` on the documented teardown paths only. Widgets/Panels treat `""` as "no error".
+> Review-approved deviations from the original plan: no `onExit` block (the state channel is process-lifetime and cleared on stop, so teardown clearing is unnecessary); no `state.set(key, nil)` (undocumented for state); low-battery re-arm also triggers on `BATTERY_CHARGING`/`BATTERY_FULL`; `no_binary` is preserved in `handleStatus(nil)`; `publishCaps` success clears `error` to `""`; battery warning fires at 0% (guard `level ~= nil and level >= 0`); config reads use `or` defaults; `warned` resets in `init()`.
 
 - [ ] **Step 2: Enable the plugin and verify the service boots**