nameplates: validate unitstr before filling the per-unit cache

cache.player and cache.minion were filled from unitstr before the two guards
that validate it, so a stale identifier poisoned the cache -- and because the
fill is gated on `== nil`, the wrong answer was never recomputed. Players read
back as cache.player == false until the plate was hidden and shown again, which
only appeared to fix it because pool reuse tripped the name/guid wipe.

Two paths produce a stale unitstr: OnUpdate dispatches a targetUpdate to
OnDataChanged before it refreshes plate.istarget, and frameState.mouseoverGuid
is only updated on gaining mouseover, never on losing it.

Hoist the PLAYER_TARGET_CHANGED distrust and the UnitName mismatch check above
the cache fill so an unverified unitstr leaves the cache nil for the next tick
instead of locking in a wrong answer.

.luarc.json

@@ -0,0 +1,22 @@
+{
+  "runtime": {
+    "version": "Lua 5.1"
+  },
+  "diagnostics": {
+    "disable": ["deprecated"],
+    "globals": [
+      "this",
+      "event",
+      "arg",
+      "arg1",
+      "arg2",
+      "arg3",
+      "arg4",
+      "arg5",
+      "arg6",
+      "arg7",
+      "arg8",
+      "arg9"
+    ]
+  }
+}

.pkgmeta

@@ -0,0 +1,4 @@
+package-as: pfUI
+
+ignore:
+  - .luarc.json

modules/chat.lua

@@ -296,6 +296,54 @@ pfUI:RegisterModule("chat", function ()
     end
   end
 
+  -- [ Chat Background Alpha ]
+  -- Blizzard's per-window transparency slider drives FCF_SetWindowAlpha, which only
+  -- touches the ChatFrame*Background textures that pfUI hides on docked frames. Mirror
+  -- the window's stored alpha onto the visible pfUI backdrop so the native slider
+  -- controls it directly. The slider is authoritative for the panel's alpha.
+  local function ApplyChatBackgroundAlpha(panel, frame)
+    if not (panel and panel.backdrop and frame) then return end
+    local _, _, _, _, _, alpha = GetChatWindowInfo(frame:GetID())
+    alpha = tonumber(alpha)
+    if not alpha then return end
+    local r, g, b = panel.backdrop:GetBackdropColor()
+    panel.backdrop:SetBackdropColor(r, g, b, alpha)
+  end
+
+  function pfUI.chat:RefreshBackgroundAlpha()
+    -- left panel follows the currently selected docked tab
+    local selected = SELECTED_CHAT_FRAME
+    if not (selected and selected:GetParent() == pfUI.chat.left) then
+      selected = ChatFrame1
+    end
+    ApplyChatBackgroundAlpha(pfUI.chat.left, selected)
+
+    if C.chat.right.enable == "1" then
+      ApplyChatBackgroundAlpha(pfUI.chat.right, ChatFrame3)
+    end
+  end
+
+  function pfUI.chat:MigrateBackgroundAlpha()
+    -- Runs once per character. The previous SetupPositions default stored a hard 0 window
+    -- alpha, which now renders the pfUI backdrop fully transparent. Restore the historical
+    -- 0.8 look for any pfUI-managed window still sitting at 0. Only existing installs that
+    -- already ran chat setup carry that legacy 0; fresh installs get 0.8 from SetupPositions.
+    if pfUI_init.chatbgalpha then return end
+    if not pfUI_init["chat_position"] then return end
+    pfUI_init.chatbgalpha = true
+
+    local frames = { ChatFrame1, ChatFrame2 }
+    if C.chat.right.enable == "1" then table.insert(frames, ChatFrame3) end
+
+    for _, frame in ipairs(frames) do
+      local _, _, _, _, _, alpha = GetChatWindowInfo(frame:GetID())
+      alpha = tonumber(alpha)
+      if alpha and alpha <= 0 then
+        FCF_SetWindowAlpha(frame, 0.8)
+      end
+    end
+  end
+
   function pfUI.chat:RefreshChat()
     local panelheight = C.global.font_size*1.5 + default_border*2 + 2
 
@@ -447,9 +495,13 @@ pfUI:RegisterModule("chat", function ()
     for index, value in pairs(DOCKED_CHAT_FRAMES) do
       FCF_UpdateButtonSide(value)
     end
+
+    pfUI.chat:RefreshBackgroundAlpha()
   end
 
   hooksecurefunc("FCF_SaveDock", pfUI.chat.RefreshChat)
+  hooksecurefunc("FCF_SetWindowAlpha", function() pfUI.chat:RefreshBackgroundAlpha() end)
+  hooksecurefunc("FCF_SelectDockFrame", function() pfUI.chat:RefreshBackgroundAlpha() end)
 
   if C.chat.global.tabmouse == "1" then
     pfUI.chat.mouseovertab = CreateFrame("Frame")
@@ -500,7 +552,7 @@ pfUI:RegisterModule("chat", function ()
     FCF_SetLocked(ChatFrame1, 1)
     FCF_SetWindowName(ChatFrame1, GENERAL)
     FCF_SetWindowColor(ChatFrame1, 0, 0, 0)
-    FCF_SetWindowAlpha(ChatFrame1, 0)
+    FCF_SetWindowAlpha(ChatFrame1, 0.8)
     FCF_SetChatWindowFontSize(ChatFrame1, 12)
     ChatFrame1:SetUserPlaced(1)
 
@@ -508,7 +560,7 @@ pfUI:RegisterModule("chat", function ()
     FCF_SetLocked(ChatFrame2, 1)
     FCF_SetWindowName(ChatFrame2, COMBAT_LOG)
     FCF_SetWindowColor(ChatFrame2, 0, 0, 0)
-    FCF_SetWindowAlpha(ChatFrame2, 0)
+    FCF_SetWindowAlpha(ChatFrame2, 0.8)
     FCF_SetChatWindowFontSize(ChatFrame2, 12)
     ChatFrame2:SetUserPlaced(1)
 
@@ -518,7 +570,7 @@ pfUI:RegisterModule("chat", function ()
       FCF_SetLocked(ChatFrame3, 1)
       FCF_SetWindowName(ChatFrame3, T["Loot & Spam"])
       FCF_SetWindowColor(ChatFrame3, 0, 0, 0)
-      FCF_SetWindowAlpha(ChatFrame3, 0)
+      FCF_SetWindowAlpha(ChatFrame3, 0.8)
       FCF_SetChatWindowFontSize(ChatFrame3, 12)
       FCF_UnDockFrame(ChatFrame3)
       FCF_SetTabPosition(ChatFrame3, 0)
@@ -566,6 +618,9 @@ pfUI:RegisterModule("chat", function ()
   end
 
   pfUI.chat:SetScript("OnEvent", function()
+    -- restore legacy chat windows stuck at 0 alpha before anything reads it
+    pfUI.chat:MigrateBackgroundAlpha()
+
     -- set the default chat
     FCF_SelectDockFrame(SELECTED_CHAT_FRAME)
 

modules/nameplates.lua

@@ -1039,13 +1039,29 @@ nameplates:RegisterEvent("PLAYER_GUILD_UPDATE")
     local mouseover = plate.cachedGuid and plate.cachedGuid == frameState.mouseoverGuid or nil
     local unitstr = target and "target" or mouseover and "mouseover" or plate.cachedGuid or nil
 
+    -- target event sometimes fires too quickly, where nameplate identifiers are not
+    -- yet updated. So while being inside this event, we cannot trust the unitstr.
+    if event == "PLAYER_TARGET_CHANGED" then unitstr = nil end
+
+    -- remove unitstr when it doesn't resolve to this plate's unit (stale istarget,
+    -- stale mouseover guid or a despawned unit). Must run before the cache fills
+    -- below -- an unrelated unitstr would poison cache.player/minion with the
+    -- *other* unit's answer, and the nil-gate would then never recompute it.
+    if unitstr and UnitName(unitstr) ~= name then unitstr = nil end
+
     -- resolve player vs npc from plate's own unit so libunitscan can't return
     -- a player record for an NPC sharing the same name (e.g. Chromie). Stored
     -- as true/false/nil so it doubles as the GetUnitInfo hint.
     if plate.cache.player == nil and unitstr then
       plate.cache.player = UnitIsPlayer(unitstr) and true or false
     end
-    local class, ulevel, elite, player, guild = GetUnitInfo(name, true, plate.cache.player)
+    if plate.cache.minion == nil and unitstr then
+      plate.cache.minion = UnitIsMinion(unitstr) and true or false
+    end
+    local class, ulevel, elite, player, guild
+    if not plate.cache.minion then
+      class, ulevel, elite, player, guild = GetUnitInfo(name, true, plate.cache.player)
+    end
     if plate.cache.player ~= nil then player = plate.cache.player or nil end
 
     -- Use database level ONLY if current level is ?? (fixes ?? after reload, but doesn't override visible levels)
@@ -1065,18 +1081,11 @@ nameplates:RegisterEvent("PLAYER_GUILD_UPDATE")
     if player and unittype == "ENEMY_NPC" then unittype = "ENEMY_PLAYER" end
     if player and unittype == "FRIENDLY_NPC" then unittype = "FRIENDLY_PLAYER" end
     elite = plate.original.levelicon:IsShown() and not player and "boss" or elite
-    if not class then plate.wait_for_scan = true end
+    if not class and not plate.cache.minion then plate.wait_for_scan = true end
 
     -- skip data updates on invisible frames
     if not visible then return end
 
-    -- target event sometimes fires too quickly, where nameplate identifiers are not
-    -- yet updated. So while being inside this event, we cannot trust the unitstr.
-    if event == "PLAYER_TARGET_CHANGED" then unitstr = nil end
-
-    -- remove unitstr on unit name mismatch
-    if unitstr and UnitName(unitstr) ~= name then unitstr = nil end
-
     -- always make sure to keep plate visible
     plate:Show()
 
@@ -1551,7 +1560,7 @@ nameplates:RegisterEvent("PLAYER_GUILD_UPDATE")
     -- otherwise an NPC sharing a name with a known player flips wait_for_scan
     -- off here, then OnDataChanged re-sets it, every frame until the mob scan
     -- lands.
-    if nameplate.wait_for_scan and GetUnitInfo(name, true, nameplate.cache.player) then
+    if nameplate.wait_for_scan and not nameplate.cache.minion and GetUnitInfo(name, true, nameplate.cache.player) then
       nameplate.wait_for_scan = nil
       update = true
     end