--[[
MSUF_UnitframeCore.lua
Central unitframe event routing + coalesced updates.
Keeps legacy public entrypoints for compatibility.
]]

local _, addon = ...

addon = addon or {}

-- =========================================================================
-- PERF LOCALS (core runtime)
--  - Reduce global table lookups in high-frequency event/render paths.
--  - Secret-safe: localizing function references only (no value comparisons).
-- =========================================================================
local type, tostring, tonumber, select = type, tostring, tonumber, select
local pairs, ipairs, next = pairs, ipairs, next
local math_min, math_max, math_floor = math.min, math.max, math.floor
local string_format, string_match, string_sub = string.format, string.match, string.sub
local UnitExists, UnitIsPlayer = UnitExists, UnitIsPlayer
local UnitHealth, UnitHealthMax = UnitHealth, UnitHealthMax
local UnitPower, UnitPowerMax = UnitPower, UnitPowerMax
local UnitPowerType = UnitPowerType
local UnitHealthPercent, UnitPowerPercent = UnitHealthPercent, UnitPowerPercent
local InCombatLockdown = InCombatLockdown
local CreateFrame, GetTime = CreateFrame, GetTime

local Core = {}
local _UFCORE_issecret = _G and _G.issecretvalue or nil

local function UFCore_CanCompareNumber(v)
    return type(v) == "number" and (not _UFCORE_issecret or not _UFCORE_issecret(v))
end

local function UFCore_SamePowerSnapshot(f, pType, cur, mx)
    if not f or f._msufPowerVisCheckNeeded then return false end
    if f._msufCachedPType ~= pType then return false end
    local prevCur, prevMax = f._msufCachedPCur, f._msufCachedPMax
    if not (UFCore_CanCompareNumber(cur) and UFCore_CanCompareNumber(mx) and UFCore_CanCompareNumber(prevCur) and UFCore_CanCompareNumber(prevMax)) then
        return false
    end
    return (prevCur == cur and prevMax == mx)
end

local function UFCore_StorePowerSnapshot(f, pType, cur, mx)
    f._msufCachedPType   = pType
    f._msufCachedPCur    = cur
    f._msufCachedPMax    = mx
    f._msufCachedPPct    = nil
    f._msufCachedPSerial = Core._frameNowSerial
end

local function UFCore_SamePowerTextSnapshot(f, pType, cur, mx)
    if not f or f._msufPwrTextForce then return false end
    if f._msufLastPwrTextType ~= pType then return false end
    local prevCur, prevMax = f._msufLastPwrTextCur, f._msufLastPwrTextMax
    if not (UFCore_CanCompareNumber(cur) and UFCore_CanCompareNumber(mx) and UFCore_CanCompareNumber(prevCur) and UFCore_CanCompareNumber(prevMax)) then
        return false
    end
    return (prevCur == cur and prevMax == mx)
end

local function UFCore_StorePowerTextSnapshot(f, pType, cur, mx)
    f._msufLastPwrTextType = pType
    f._msufLastPwrTextCur  = cur
    f._msufLastPwrTextMax  = mx
    f._msufPwrTextForce    = nil
end

-- Hotpath locals: _G ref + unpack (kept for unpack compat, all others already localized above)
local _G = _G
-- Lua 5.1 (WoW) uses global unpack; some environments expose table.unpack
local unpack = _G.unpack
if not unpack then
    local tbl = _G.table
    unpack = tbl and tbl.unpack
end

-- Forward decl (used by settings cache + helpers below the definition).
local UFCore_EnsureDBOnce

-- ------------------------------------------------------------
-- Settings snapshot cache (UFCore budgets + color/config fast path)
--  - Rebuilt on login/entering world and on NotifyConfigChanged().
--  - Safe to call lazily; never touches secure/secret values.
-- ------------------------------------------------------------
Core._settingsCache = Core._settingsCache or { valid = false }

local DEFAULT_NPC_COLORS = {
    friendly = { 0, 1, 0 },
    neutral  = { 1, 1, 0 },
    enemy    = { 0.85, 0.10, 0.10 },
    dead     = { 0.4, 0.4, 0.4 },
    -- NPC Type Colors (npcColorMode == "type") — Platynator defaults
    npcBoss      = { 0.74, 0.11, 0.00 },   -- #bc1c00 dark red
    npcMiniboss  = { 0.56, 0.00, 0.74 },   -- #9000bc purple
    npcCaster    = { 0.00, 0.45, 0.74 },   -- #0074bc blue
    npcMelee     = { 0.99, 0.99, 0.99 },   -- #fcfcfc white (Platynator default)
    npcRegular   = { 0.70, 0.56, 0.33 },   -- #b28e55 tan
}

local function UFCore_Clamp01(v, def)
    if type(v) ~= "number" then return def end
    if v < 0 then return 0 elseif v > 1 then return 1 end
    return v
end

local function UFCore_ClampNum(v, def, minv, maxv)
    if type(v) ~= "number" then v = def end
    if v < minv then v = minv elseif v > maxv then v = maxv end
    return v
end

-- Forward declaration: used by fast-path helpers defined above the cache implementation.
local UFCore_GetSettingsCache

-- PERF: File-scope cached debug flag (set in RefreshSettingsCache, read in MarkDirty).
-- Eliminates UFCore_GetSettingsCache() call from the hottest path (~500 calls/sec in raids).
local _ufcoreDebugDirty = false
-- PERF: File-scope cached flush budget values (set in RefreshSettingsCache).
-- Eliminates UFCore_GetSettingsCache() from Flush and FlushTask hot paths.
local _ufcoreFlushBudgetMs = 0.35  -- PERF: Hard-cap per-flush spike. Target: combined MSUF < 800μs/frame.
local _ufcoreUrgentMax = 10

-- NPC Type Colors: only active in 5-man instances (party).
-- Updated on PLAYER_ENTERING_WORLD / ZONE_CHANGED_NEW_AREA.
local _npcTypeInstanceActive = false

-- ── Smooth power bar + real-time text (MidnightRogueBars-style) ──
-- _smoothPowerBar:    ExponentialEaseOut on StatusBar (fluid animation).
-- _realtimePowerText: Text updated every event (no budget gating).
-- Both ON  = MidnightRogueBars hyper-accurate mode.
-- Both OFF = Classic MSUF battery-saver mode.
local _smoothPowerBar    = true
local _realtimePowerText = true

local function UFCore_RefreshSettingsCache(reason)
    local cache = Core._settingsCache or {}
    Core._settingsCache = cache

    local db = _G.MSUF_DB
    if not db and type(UFCore_EnsureDBOnce) == "function" then
        db = UFCore_EnsureDBOnce()
    end

    cache.dbRef = db
    local g = (db and type(db.general) == "table") and db.general or nil
    cache.generalRef = g
    cache.classColorsRef = (db and type(db.classColors) == "table") and db.classColors or nil
    cache.npcColorsRef = (db and type(db.npcColors) == "table") and db.npcColors or nil

    Core._settingsSerial = (Core._settingsSerial or 0) + 1
    cache.settingsSerial = Core._settingsSerial
    _G.MSUF_UFCORE_SETTINGS_SERIAL = Core._settingsSerial

    -- UFCore budgets
    cache.ufcoreFlushBudgetMs = UFCore_ClampNum(g and g.ufcoreFlushBudgetMs, 0.6, 0.25, 2.0)

    local urgentMax = g and g.ufcoreUrgentMaxPerFlush
    if type(urgentMax) ~= "number" then urgentMax = 10 end
    urgentMax = math.floor(urgentMax + 0.5)
    if urgentMax < 1 then urgentMax = 1 elseif urgentMax > 200 then urgentMax = 200 end
    cache.ufcoreUrgentMaxPerFlush = urgentMax

    -- Name coloring switches (identity fast path)
    cache.nameClassColor = (g and g.nameClassColor) and true or false
    cache.npcNameRed = (g and g.npcNameRed) and true or false

    -- Debug flag: record last dirty reason/mask on frames (hotpath uses cache to avoid DB reads).
    cache.ufcoreDebugDirty = (g and g.ufcoreDebugDirty) and true or false
    _ufcoreDebugDirty = cache.ufcoreDebugDirty
    -- PERF: Sync file-scope budget locals (read by Flush/FlushTask without cache lookup).
    _ufcoreFlushBudgetMs = cache.ufcoreFlushBudgetMs
    _ufcoreUrgentMax = cache.ufcoreUrgentMaxPerFlush

    -- Global indicator defaults (used by Indicators element when per-unit overrides are nil).
    cache.showLeaderIconDefault = (g and g.showLeaderIcon ~= false) and true or false
    cache.showRaidMarkerDefault = (g and g.showRaidMarker ~= false) and true or false

    -- Bars config snapshot (power bar visibility gating; avoids reading MSUF_DB.bars in ComputeElementMask hot paths).
    local bars = (db and type(db.bars) == "table") and db.bars or nil
    cache.barsRef = bars
    cache.showPlayerPowerBar = not (bars and bars.showPlayerPowerBar == false)
    cache.showTargetPowerBar = not (bars and bars.showTargetPowerBar == false)
    cache.showFocusPowerBar  = not (bars and bars.showFocusPowerBar == false)
    cache.showBossPowerBar   = not (bars and bars.showBossPowerBar == false)
    -- Bars: Aggro indicator (Target/Focus/Boss) - mode: 'off' | 'border'
    local ag = g and g.aggroIndicatorMode
    if ag ~= "border" then ag = nil end
    if not ag and g and g.enableAggroHighlight == true then ag = "border" end -- legacy migrate
    cache.aggroIndicatorMode = ag or "off"

    -- Boss Target Highlight
    cache.bossTargetHLEnabled = (g and g.bossTargetHighlightEnabled ~= false) and true or false
    local btc = g and g.bossTargetHighlightColor
    if type(btc) == "table" then
        cache.bossTargetHLR = btc[1] or 1
        cache.bossTargetHLG = btc[2] or 0.82
        cache.bossTargetHLB = btc[3] or 0
    else
        cache.bossTargetHLR, cache.bossTargetHLG, cache.bossTargetHLB = 1, 0.82, 0
    end

    -- Smooth power bar + real-time text (hot-path upvalues).
    -- Default ON (true) when not explicitly set. Matches MidnightRogueBars behavior.
    local prevEither = (_smoothPowerBar or _realtimePowerText)
    _smoothPowerBar    = not (bars and bars.smoothPowerBar == false)
    _realtimePowerText = not (bars and bars.realtimePowerText == false)
    local nowEither = (_smoothPowerBar or _realtimePowerText)

    -- Swap DIRECT_APPLY handler to match new settings (zero branches in hot path).
    if Core._PowerSwapHandler then Core._PowerSwapHandler() end

    -- When the "either toggle ON" state changes, re-register events on all frames.
    -- This adds/removes UNIT_POWER_FREQUENT → true zero overhead when both off.
    if (prevEither ~= nowEither) and Core.RefreshAllUnitEvents then
        Core.RefreshAllUnitEvents(true)
    end

    -- Bar mode (authoritative): "dark" | "class" | "unified"
    local mode = g and g.barMode or nil
    if mode ~= "dark" and mode ~= "class" and mode ~= "unified" then
        mode = (g and g.useClassColors and "class") or (g and g.darkMode and "dark") or "dark"
    end
    cache.barMode = mode

    -- NPC Color Mode: "reaction" (default) or "type" (classification-based)
    -- Force "reaction" outside 5-man instances → zero overhead in raids/solo.
    local npcCM = g and g.npcColorMode or nil
    if npcCM ~= "type" then npcCM = "reaction" end
    if not _npcTypeInstanceActive then npcCM = "reaction" end
    cache.npcColorMode = npcCM
    cache.npcTypeColorBar  = (npcCM == "type") and (g and g.npcTypeColorBar ~= false) and true or false
    cache.npcTypeColorText = (npcCM == "type") and (g and g.npcTypeColorText ~= false) and true or false
    -- Per-unit NPC type enable (only evaluated when npcColorMode == "type")
    cache.npcTypeTarget = (g and g.npcTypeTarget ~= false) and true or false
    cache.npcTypeFocus  = (g and g.npcTypeFocus  ~= false) and true or false
    cache.npcTypeBoss   = (g and g.npcTypeBoss   ~= false) and true or false
    cache.npcTypeToT    = (g and g.npcTypeToT    ~= false) and true or false

    -- Dark bar color
    local darkR, darkG, darkB = 0, 0, 0
    local gray = g and g.darkBarGray
    if type(gray) == "number" then
        gray = UFCore_Clamp01(gray, 0)
        darkR, darkG, darkB = gray, gray, gray
    else
        local toneKey = (g and g.darkBarTone) or "black"
        local tone = _G.MSUF_DARK_TONES and _G.MSUF_DARK_TONES[toneKey]
        if tone then
            darkR, darkG, darkB = tone[1] or 0, tone[2] or 0, tone[3] or 0
        end
    end
    cache.darkBarR, cache.darkBarG, cache.darkBarB = darkR, darkG, darkB

    -- Unified bar color
    cache.unifiedBarR = UFCore_Clamp01(g and g.unifiedBarR, 0.10)
    cache.unifiedBarG = UFCore_Clamp01(g and g.unifiedBarG, 0.60)
    cache.unifiedBarB = UFCore_Clamp01(g and g.unifiedBarB, 0.90)

    -- Static background-tint snapshot (used by main-file background visual apply).
    cache.darkBgCustomColor = (g and g.darkBgCustomColor) and true or false
    cache.darkBgBrightness = UFCore_Clamp01(g and g.darkBgBrightness, 1)
    cache.barBgMatchHPColor = (g and g.barBgMatchHPColor) and true or false
    cache.powerBarBgMatchHPColor = ((g and g.powerBarBgMatchHPColor) or (bars and bars.powerBarBgMatchBarColor)) and true or false
    cache.anyBarBackgroundTracksHPColor = (cache.barBgMatchHPColor or cache.powerBarBgMatchHPColor) and true or false

    local bgAlphaPct = type(bars and bars.barBackgroundAlpha) == "number" and bars.barBackgroundAlpha or 90
    if bgAlphaPct < 0 then bgAlphaPct = 0 elseif bgAlphaPct > 100 then bgAlphaPct = 100 end
    cache.barBackgroundAlpha = bgAlphaPct / 100

    local bgR = UFCore_Clamp01(g and g.classBarBgR, 0)
    local bgG = UFCore_Clamp01(g and g.classBarBgG, 0)
    local bgB = UFCore_Clamp01(g and g.classBarBgB, 0)
    if g and g.darkMode and not cache.darkBgCustomColor then
        local br = cache.darkBgBrightness
        bgR, bgG, bgB = bgR * br, bgG * br, bgB * br
    end
    cache.barBgTintR, cache.barBgTintG, cache.barBgTintB, cache.barBgTintA = bgR, bgG, bgB, 0.9

    local pbgR, pbgG, pbgB = g and g.powerBarBgColorR, g and g.powerBarBgColorG, g and g.powerBarBgColorB
    if type(pbgR) == "number" and type(pbgG) == "number" and type(pbgB) == "number" then
        pbgR = UFCore_Clamp01(pbgR, 0)
        pbgG = UFCore_Clamp01(pbgG, 0)
        pbgB = UFCore_Clamp01(pbgB, 0)
        if g and g.darkMode and not cache.darkBgCustomColor then
            local br = cache.darkBgBrightness
            pbgR, pbgG, pbgB = pbgR * br, pbgG * br, pbgB * br
        end
    else
        pbgR, pbgG, pbgB = bgR, bgG, bgB
    end
    cache.powerBgTintR, cache.powerBgTintG, cache.powerBgTintB, cache.powerBgTintA = pbgR, pbgG, pbgB, 0.9

    -- Pet frame override color (only used in "class" bar mode)
    local pr, pg, pb = g and g.petFrameColorR, g and g.petFrameColorG, g and g.petFrameColorB
    if type(pr) == "number" and type(pg) == "number" and type(pb) == "number" then
        cache.petFrameColorR = UFCore_Clamp01(pr, 0)
        cache.petFrameColorG = UFCore_Clamp01(pg, 0)
        cache.petFrameColorB = UFCore_Clamp01(pb, 0)
        cache.petFrameColorEnabled = true
    else
        cache.petFrameColorEnabled = false
    end

    -- NPC reaction colors (resolved once per refresh)
    local npc = cache.npcColor
    if type(npc) ~= "table" then npc = {}; cache.npcColor = npc end
    for kind, def in pairs(DEFAULT_NPC_COLORS) do
        local t = cache.npcColorsRef and cache.npcColorsRef[kind] or nil
        local out = npc[kind]
        if type(out) ~= "table" then out = {}; npc[kind] = out end
        if type(t) == "table" and type(t.r) == "number" and type(t.g) == "number" and type(t.b) == "number" then
            out[1], out[2], out[3] = t.r, t.g, t.b
        else
            out[1], out[2], out[3] = def[1], def[2], def[3]
        end
    end

    -- Class color cache (computed lazily per class token)
    cache.classColorCache = {}

    cache.valid = true
    cache._lastReason = reason
end

-- ---------------------------------------------------------------------------
-- Aggro indicator (Target/Focus/Boss): re-use the existing HP outline border
-- as an aggro warning (orange). Event-driven via UNIT_THREAT_*.
--
-- Behavior:
--  - If Outline border is enabled (Bars->Outline), that same border turns orange
--    while you have aggro on the unit, otherwise it stays black.
--  - If Outline border is disabled, we temporarily show a thick (1px) outline
--    ONLY while you have aggro.
-- ---------------------------------------------------------------------------

local function UFCore_UpdateAggroBorder(frame, unit)
    if not frame then return end

    local cache = UFCore_GetSettingsCache()
    local mode = cache and cache.aggroIndicatorMode or "off"
    if mode ~= "border" then
        if frame._msufAggroOutlineOn then
            frame._msufAggroOutlineOn = nil
            if _G.MSUF_RefreshRareBarVisuals then _G.MSUF_RefreshRareBarVisuals(frame) end
        end
        return
    end

    if not unit or not UnitExists(unit) then
        if frame._msufAggroOutlineOn then
            frame._msufAggroOutlineOn = nil
            if _G.MSUF_RefreshRareBarVisuals then _G.MSUF_RefreshRareBarVisuals(frame) end
        end
        return
    end

    local on = false
    if UnitThreatSituation then
        local raw = UnitThreatSituation("player", unit)
        if raw == nil then
            on = false
        elseif _UFCORE_issecret and _UFCORE_issecret(raw) then
            return  -- secret: keep last known state, don't thrash RefreshRareBarVisuals
        else
            on = (raw == 3) and true or false
        end
    end

    if frame._msufAggroOutlineOn == on then
        return
    end
    frame._msufAggroOutlineOn = on

    if _G.MSUF_RefreshRareBarVisuals then
        _G.MSUF_RefreshRareBarVisuals(frame)
    end
end

UFCore_GetSettingsCache = function()
    local cache = Core._settingsCache
    if cache and cache.valid then
        -- PERF: Per-flush-cycle fast path. If we already validated this cycle,
        -- skip the 4 table-reference comparisons (saves ~1μs per call, 3-5 calls/cycle).
        local fSerial = Core._flushSettingsCacheSerial
        if fSerial and cache._flushSerial == fSerial then
            return cache
        end
        local db = _G.MSUF_DB
        if db and (cache.dbRef ~= db or cache.generalRef ~= db.general or cache.classColorsRef ~= db.classColors or cache.npcColorsRef ~= db.npcColors) then
            UFCore_RefreshSettingsCache("DB_SWAP")
        end
        if fSerial then cache._flushSerial = fSerial end
        return Core._settingsCache
    end
    UFCore_RefreshSettingsCache("LAZY")
    local fSerial = Core._flushSettingsCacheSerial
    if fSerial then Core._settingsCache._flushSerial = fSerial end
    return Core._settingsCache
end

addon.MSUF_UnitframeCore = Core

-- Deferred layout application (combat safety)
Core._layoutDeferredSet = Core._layoutDeferredSet or {}

-- ------------------------------------------------------------
-- Locals (perf + clarity; behavior-preserving) — additional APIs
-- (core builtins already localized at file top)
-- ------------------------------------------------------------
local debugprofilestop = debugprofilestop
local UnitName = UnitName
local UnitLevel = UnitLevel
local UnitClass = UnitClass
local UnitReaction = UnitReaction
local UnitIsDeadOrGhost = UnitIsDeadOrGhost
local UnitIsGroupLeader = UnitIsGroupLeader
local UnitIsGroupAssistant = UnitIsGroupAssistant
local GetRaidTargetIndex = GetRaidTargetIndex
local SetRaidTargetIconTexture = SetRaidTargetIconTexture
local wipe = wipe or table.wipe or function(t) if t then for k in pairs(t) do t[k] = nil end end end

local bit = _G.bit
local bit32 = _G.bit32

local bor = (bit and bit.bor) or (bit32 and bit32.bor)
local band = (bit and bit.band) or (bit32 and bit32.band)
local bnot = (bit and bit.bnot) or (bit32 and bit32.bnot)

if not (bor and band and bnot) then error("MSUF_UnitframeCore: missing bitops") end

-- ------------------------------------------------------------
-- Dirty flags (future: element updates)
-- ------------------------------------------------------------

local DIRTY_FULL      = 0xFFFFFFFF
local DIRTY_HEALTH    = 0x00000001
local DIRTY_POWER     = 0x00000002
local DIRTY_IDENTITY  = 0x00000004
local DIRTY_PORTRAIT  = 0x00000008
local DIRTY_STATUS    = 0x00000010
local DIRTY_INDICATOR = 0x00000020
local DIRTY_TOTINLINE = 0x00000040

local DIRTY_LAYOUT   = 0x00000080
local DIRTY_VISUAL   = 0x00000100  -- forces a one-shot legacy pass for bar color/gradients/background on unit swaps
local DIRTY_THREAT   = 0x00000200  -- PERF: lightweight threat-only path (alpha + aggro border, NO status text/icons)

local MASK_UNIT_EVENT_FALLBACK = bor(DIRTY_HEALTH, DIRTY_POWER, DIRTY_IDENTITY, DIRTY_STATUS, DIRTY_PORTRAIT, DIRTY_INDICATOR, DIRTY_TOTINLINE)
local MASK_UNIT_SWAP = bor(DIRTY_HEALTH, DIRTY_POWER, DIRTY_IDENTITY, DIRTY_STATUS, DIRTY_INDICATOR, DIRTY_TOTINLINE)

-- When a frame becomes visible again, refresh only dynamic values (no layout).
-- This matches the "no layout in runtime" goal while preventing stale displays after being hidden.
local MASK_SHOW_REFRESH = MASK_UNIT_SWAP

-- ------------------------------------------------------------
-- Frame registry
-- ------------------------------------------------------------

local FramesByUnit = {}

local function InitUnitFlags(f)
    if not f or f._msufUnitFlagsInited then return end
    local u = f.unit
    f._msufIsPlayer = (u == "player")
    f._msufIsTarget = (u == "target")
    f._msufIsFocus  = (u == "focus")
    f._msufIsPet    = (u == "pet")
    f._msufIsToT    = (u == "targettarget")
    -- Perf: avoid pattern matching.
    local bi = (_G.MSUF_GetBossIndexFromToken and _G.MSUF_GetBossIndexFromToken(u))
    f._msufBossIndex = bi or nil
    f._msufUnitFlagsInited = true
end

local function UFCore_RefreshFrameInvariantFlags(f, cache)
    if not f then return end
    cache = cache or UFCore_GetSettingsCache()
    local mode = (cache and cache.barMode) or "dark"

    local staticHealthColor = false
    if mode == "dark" or mode == "unified" then
        staticHealthColor = true
    elseif f._msufIsPlayer then
        staticHealthColor = true
    elseif f._msufIsPet and cache and cache.petFrameColorEnabled then
        staticHealthColor = true
    end

    f._msufStaticHealthColor = staticHealthColor and true or false
    f._msufAnyBgTracksHealthColor = (cache and cache.anyBarBackgroundTracksHPColor) and true or false
end

local function GetConfForUnit(unit)
    local db = UFCore_EnsureDBOnce()
    if not db or not unit then return nil end
    return db[unit]
end

local function GetFrameConf(f)
    if not f then return nil end
    local conf = f.cachedConfig
    if (not conf) and f.msufConfigKey then
        conf = GetConfForUnit(f.msufConfigKey)
        f.cachedConfig = conf
    end
    return conf
end

-- ------------------------------------------------------------
-- DB bootstrap (keep EnsureDB/Migration out of hot paths)
-- ------------------------------------------------------------

UFCore_EnsureDBOnce = function()
    local db = _G.MSUF_DB
    if db then
        Core._dbEnsured = true
        return db
    end

    -- If DB vanished after having been ensured (shouldn't), allow Ensure again.
    if Core._dbEnsured then
        Core._dbEnsured = nil
    end

    if not Core._dbEnsured then
        local fn = _G.EnsureDB
        if type(fn) == "function" then
            fn()
        end
        Core._dbEnsured = true
    end
    return _G.MSUF_DB
end

-- Cache the Target->ToT inline config node (table reference; stays live as settings change).
Core._totInlineConfDB = Core._totInlineConfDB or nil
Core._totInlineConfRef = Core._totInlineConfRef or nil
Core._totInlineConfMigrated = Core._totInlineConfMigrated or nil

-- Explicit cache invalidation hook (does not change behavior unless called).
-- Useful when profiles/settings swap out MSUF_DB tables and cachedConfig would otherwise stay stale.
function Core.InvalidateAllFrameConfigs()
    for _, f in pairs(FramesByUnit) do
        if f then
            f.cachedConfig = nil
            -- PERF: Invalidate per-frame combat hot-path caches (absorb text, HP/power text config, status config).
            f._msufCachedShowAbsorbText = nil
            f._msufAbsorbTextDirty = true
            f._msufCachedAbsorbText = nil
            f._msufCachedAbsorbStyle = nil
            f._msufFlushHP = nil
            f._msufFlushMaxHP = nil
            f._msufPwrTextConf = nil
            f._msufHpTextConf = nil
            f._msufPwrPctCleared = nil
            f._msufHpTxtAt = nil
            f._msufStatusConf = nil
            f._msufStatusIconsConf = nil
            f._msufTextSpec = nil
            -- PERF: Invalidate component-level diff caches (Text.lua fast-path guards)
            f._msufLastH = nil
            f._msufLastPctS = nil
            f._msufLastPwrC = nil
            f._msufLastPwrM = nil
            f._msufLastPwrP = nil
            -- PERF: Invalidate raw-value power diff guard (Text.lua P0 guard)
            f._msufRawPwrC = nil
            f._msufRawPwrM = nil
            f._msufRawPwrP = nil
        end
    end
end

-- ------------------------------------------------------------
-- Element enablement (oUF-like: only register events for enabled elements)
-- ------------------------------------------------------------

local EL_HEALTH    = 0x00000001
local EL_POWER     = 0x00000002
local EL_IDENTITY  = 0x00000004
local EL_PORTRAIT  = 0x00000008
local EL_STATUS    = 0x00000010
local EL_TOTINLINE = 0x00000020
local EL_INDICATOR = 0x00000040

-- ------------------------------------------------------------
-- Elements (oUF-style contracts, minimal)
--  - Enable/Disable: element lifecycle (event needs handled elsewhere)
--  - Update: does the smallest possible work for that element
-- Notes:
--  - Health/Power use existing fast helpers if present.
--  - Portrait uses MSUF_UpdatePortraitIfNeeded (layout is stamp-gated).
--  - Identity/Status currently fall back to the legacy full update for correctness.
-- ------------------------------------------------------------

local Elements = {}
local UFCore_GetTargetToTInlineConf -- forward decl (used by ToTInline before its definition)
Core.Elements = Elements

-- Fast function refs (resolved once; avoids _G lookups in element hot paths).
local FN_UpdateHealthFast, FN_UpdateHpTextFast, FN_UpdatePowerBarFast, FN_UpdatePowerTextFast, FN_SetTextIfChanged
local FN_SetShown, FN_GetConfiguredFontColor, FN_ApplyUnitAlpha, FN_UpdateStatusIndicatorForFrame, FN_EnsureDB, FN_ClampNameWidth, FN_ApplyLeaderIconLayout, FN_ApplyRaidMarkerLayout
-- PERF: File-scope caches for functions resolved in RunUpdate/RunVisual/RunWarmup
-- (eliminates _G hash lookup per call; stable after PLAYER_LOGIN).
local FN_UpdateSimpleUnitFrame, FN_RefreshRareBarVisuals

local function UFCore_ResolveFn(cur, key)
    if cur then return cur end
    local fn = _G[key]; return (type(fn) == "function") and fn or nil
end

local function UFCore_ResolveFastFns()
    -- Resolve lazily; safe to call multiple times (non-hot paths only).
    FN_UpdateHealthFast = UFCore_ResolveFn(FN_UpdateHealthFast, "MSUF_UFCore_UpdateHealthFast"); FN_UpdateHpTextFast = UFCore_ResolveFn(FN_UpdateHpTextFast, "MSUF_UFCore_UpdateHpTextFast")
    FN_UpdatePowerBarFast = UFCore_ResolveFn(FN_UpdatePowerBarFast, "MSUF_UFCore_UpdatePowerBarFast"); FN_UpdatePowerTextFast = UFCore_ResolveFn(FN_UpdatePowerTextFast, "MSUF_UFCore_UpdatePowerTextFast")
    FN_SetTextIfChanged = UFCore_ResolveFn(FN_SetTextIfChanged, "MSUF_SetTextIfChanged"); FN_SetShown = UFCore_ResolveFn(FN_SetShown, "MSUF_SetShown")
    FN_GetConfiguredFontColor = UFCore_ResolveFn(FN_GetConfiguredFontColor, "MSUF_GetConfiguredFontColor"); FN_ApplyUnitAlpha = UFCore_ResolveFn(FN_ApplyUnitAlpha, "MSUF_ApplyUnitAlpha")
    FN_UpdateStatusIndicatorForFrame = UFCore_ResolveFn(FN_UpdateStatusIndicatorForFrame, "MSUF_UpdateStatusIndicatorForFrame"); FN_EnsureDB = UFCore_ResolveFn(FN_EnsureDB, "EnsureDB")
    FN_ClampNameWidth = UFCore_ResolveFn(FN_ClampNameWidth, "MSUF_ClampNameWidth"); FN_ApplyLeaderIconLayout = UFCore_ResolveFn(FN_ApplyLeaderIconLayout, "MSUF_ApplyLeaderIconLayout")
    FN_ApplyRaidMarkerLayout = UFCore_ResolveFn(FN_ApplyRaidMarkerLayout, "MSUF_ApplyRaidMarkerLayout")
end

local function _SetShown(obj, show)
    if not obj then return end
    -- PERF: After UFCore_ResolveFastFns() (PLAYER_LOGIN), FN_SetShown is always resolved.
    -- Eliminated: per-call UFCore_ResolveFn fallback + boolean coercion overhead.
    local fn = FN_SetShown
    if fn then fn(obj, show and true or false); return end
    -- Cold fallback (only before PLAYER_LOGIN):
    if show then if obj.Show then obj:Show() end else if obj.Hide then obj:Hide() end end
end

local function _SetText(fs, txt)
    if not fs then return end
    -- PERF: After UFCore_ResolveFastFns() (PLAYER_LOGIN), FN_SetTextIfChanged is always resolved.
    -- Eliminated: per-call nil-coerce of txt + fallback method check.
    local fn = FN_SetTextIfChanged
    if fn then fn(fs, txt or ""); return end
    -- Cold fallback (only before PLAYER_LOGIN):
    if fs.SetText then fs:SetText(txt or "") end
end

local UFCore_GetNPCReactionColorFast, UFCore_GetClassBarColorFast

-- P4: Cache per-frame unit identity facts computed from C API.
-- Updated once per DIRTY_IDENTITY (unit swap, UNIT_FACTION, UNIT_NAME_UPDATE).
-- Both color paths read the cache; zero C API calls during UNIT_HEALTH.
-- Secret-safe: UnitIsPlayer returns a plain bool; UnitReaction is a plain number.
local function _RefreshUnitIdentityCache(frame)
    local unit = frame.unit
    if not unit or not UnitExists(unit) then
        frame._msufCachedIsPlayer     = false
        frame._msufCachedReactionKind = "enemy"
        frame._msufNpcTypeColored     = nil
        return
    end
    frame._msufCachedIsPlayer = (UnitIsPlayer(unit) and true) or false
    frame._msufNpcTypeColored = nil
    if not frame._msufCachedIsPlayer then
        if UnitIsDeadOrGhost(unit) then
            frame._msufCachedReactionKind = "dead"
        elseif frame._msufBossIndex then
            frame._msufCachedReactionKind = "enemy"
        else
            local raw = UnitReaction and UnitReaction("player", unit) or nil
            local r = tonumber(raw)
            if r then
                if r >= 5 then
                    frame._msufCachedReactionKind = "friendly"
                elseif r == 4 then
                    frame._msufCachedReactionKind = "neutral"
                else
                    frame._msufCachedReactionKind = "enemy"
                end
            else
                frame._msufCachedReactionKind = "enemy"
            end
        end

        -- NPC Type override: replace "enemy" with classification-based key.
        -- Gated by cache.npcColorMode which is forced to "reaction" outside 5-man.
        -- All APIs return plain values — secret-safe in 12.0 Midnight.
        local kind = frame._msufCachedReactionKind
        if kind == "enemy" or (kind == nil) then
            local cache = UFCore_GetSettingsCache()
            if cache and cache.npcColorMode == "type" then
                -- Per-unit gate: check if this frame type has NPC type enabled
                local unitAllowed = true
                if frame._msufIsTarget then unitAllowed = cache.npcTypeTarget
                elseif frame._msufIsFocus then unitAllowed = cache.npcTypeFocus
                elseif frame._msufBossIndex then unitAllowed = cache.npcTypeBoss
                elseif frame._msufIsToT then unitAllowed = cache.npcTypeToT
                end
                if unitAllowed then
                local cls = UnitClassification(unit)
                if cls == "worldboss" or cls == "boss" then
                    frame._msufCachedReactionKind = "npcBoss"
                elseif cls == "elite" or cls == "rareelite" then
                    -- Dungeon bosses return "elite" but have skull level (-1).
                    -- UnitEffectiveLevel returns a plain number — safe in 12.0.
                    local level = UnitEffectiveLevel and UnitEffectiveLevel(unit) or 0
                    if level == -1 then
                        frame._msufCachedReactionKind = "npcBoss"
                    elseif UnitIsLieutenant and UnitIsLieutenant(unit) then
                        frame._msufCachedReactionKind = "npcMiniboss"
                    else
                        local uclass = UnitClassBase and UnitClassBase(unit)
                        if uclass == "PALADIN" then
                            frame._msufCachedReactionKind = "npcCaster"
                        else
                            frame._msufCachedReactionKind = "npcMelee"
                        end
                    end
                elseif cls == "rare" then
                    frame._msufCachedReactionKind = "npcMiniboss"
                else -- "normal", "trivial", "minus"
                    frame._msufCachedReactionKind = "npcRegular"
                end
                frame._msufNpcTypeColored = true
                end -- unitAllowed
            end
        end
    end
end

local function _UpdateIdentityColors(frame)
    if not frame or not frame.nameText then return end

    local cache = UFCore_GetSettingsCache()
    local unit = frame.unit

    local r, g, b

    -- P4: read identity cache (set once per DIRTY_IDENTITY, not per UNIT_HEALTH).
    local isPlayer = frame._msufCachedIsPlayer
    if isPlayer == nil then
        -- cold start: populate cache now (first Identity update)
        _RefreshUnitIdentityCache(frame)
        isPlayer = frame._msufCachedIsPlayer
    end

    if cache and cache.nameClassColor and isPlayer then
        local _, classToken = UnitClass(unit)
        if classToken then
            r, g, b = UFCore_GetClassBarColorFast(classToken)
        end

    elseif cache and cache.npcNameRed and unit and UnitExists(unit) and not isPlayer then
        local kind = frame._msufCachedReactionKind or "enemy"
        -- If NPC type coloring is active but text toggle is off, fall back to "enemy"
        if frame._msufNpcTypeColored and not cache.npcTypeColorText then
            kind = "enemy"
        end
        r, g, b = UFCore_GetNPCReactionColorFast(kind)
    end

    if r == nil then
        local fn = FN_GetConfiguredFontColor
        if fn then r, g, b = fn() end
    end

    r, g, b = r or 1, g or 1, b or 1
    frame.nameText:SetTextColor(r, g, b, 1)
    if frame.levelText then frame.levelText:SetTextColor(r, g, b, 1) end
end

local function UFCore_UpdateIdentityFast(frame, conf)
    if not frame then return false end
    -- Boss test mode relies on the legacy renderer for fake labels.
    if frame.isBoss and _G.MSUF_BossTestMode then
        return false
    end

    local unit = frame.unit
    local exists = unit and UnitExists(unit)

    -- P4: refresh identity cache on every DIRTY_IDENTITY pass.
    -- This is the only place UnitIsPlayer + UnitReaction are called for non-player frames.
    if exists then _RefreshUnitIdentityCache(frame) end

    local showName = (frame.showName ~= false)
    if conf and conf.showName ~= nil then
        showName = (conf.showName ~= false)
    end

    if frame.nameText then
        if showName and exists then
            _SetText(frame.nameText, UnitName(unit) or "")
        else
            _SetText(frame.nameText, "")
        end
        _SetShown(frame.nameText, showName and exists)
    end

    if frame.levelText then
        local showLevel = false
        if conf and conf.showLevelIndicator == true then
            showLevel = exists and true or false
        end
        if showLevel then
            local lvl = UnitLevel(unit)
            local n = tonumber(lvl)
            if not n or n <= 0 then
                _SetText(frame.levelText, "??")
            else
                _SetText(frame.levelText, tostring(n))
            end
        else
            _SetText(frame.levelText, "")
        end
        _SetShown(frame.levelText, showLevel)
    end

    -- Keep identity coloring in sync if either name OR level is visible.
    if exists then
        if (showName == true) or (conf and conf.showLevelIndicator == true) then
            _UpdateIdentityColors(frame)
        end
    end

    return true
end

local function UFCore_UpdateStatusFast(frame, conf)
    if not frame then return false end
    local key = frame.msufConfigKey
    -- PERF: FN_ApplyUnitAlpha / FN_UpdateStatusIndicatorForFrame are resolved
    -- once in UFCore_ResolveFastFns (PLAYER_LOGIN). No per-call resolve needed.
    local fn = FN_ApplyUnitAlpha; if fn then fn(frame, key) end
    fn = FN_UpdateStatusIndicatorForFrame; if fn then fn(frame) end

    -- Aggro highlight overlay (Target/Focus/Boss only)
    if frame.aggroHighlightTex then
        UFCore_UpdateAggroBorder(frame, frame.unit)
    end
    return true
end

-- PERF: Lightweight threat-only update. UNIT_THREAT fires 5-20x/sec per boss in raids.
-- Threat changes do not imply range/combat/load-condition alpha changes, so avoid
-- re-running the Alpha pipeline here. Threat only needs the aggro border.
local function UFCore_UpdateThreatFast(frame)
    if not frame then return false end
    if frame.aggroHighlightTex then
        UFCore_UpdateAggroBorder(frame, frame.unit)
    end
    return true
end

-- ---------------------------------------------------------------------------
-- UFCore: fast health bar color refresh (fixes "unit colors not updating" after
-- spike fix removed legacy full UpdateSimpleUnitFrame() on target/focus swaps).
--
-- Why needed: MSUF_UFCore_UpdateHealthFast() updates min/max + value, but does
-- NOT set hpBar:SetStatusBarColor(). That is normally done in the main file's
-- heavy-visual pass, which we no longer run on every unit swap.
-- ---------------------------------------------------------------------------

UFCore_GetNPCReactionColorFast = function(kind)
    local cache = UFCore_GetSettingsCache()
    local t = cache and cache.npcColor and cache.npcColor[kind]
    if t then
        return t[1], t[2], t[3]
    end
    local def = DEFAULT_NPC_COLORS[kind]
    if def then
        return def[1], def[2], def[3]
    end
    return 1, 1, 1
end

UFCore_GetClassBarColorFast = function(classToken)
    local defaultR, defaultG, defaultB = 0, 1, 0
    if not classToken then
        return defaultR, defaultG, defaultB
    end

    local cache = UFCore_GetSettingsCache()
    local cc = cache and cache.classColorCache
    local hit = cc and cc[classToken]
    if hit then
        return hit[1], hit[2], hit[3]
    end

    local r, g, b

    local override = cache and cache.classColorsRef and cache.classColorsRef[classToken] or nil
    if type(override) == "table" and type(override.r) == "number" and type(override.g) == "number" and type(override.b) == "number" then
        r, g, b = override.r, override.g, override.b
    elseif type(override) == "string" and type(_G.MSUF_FONT_COLORS) == "table" and type(_G.MSUF_FONT_COLORS[override]) == "table" then
        local c = _G.MSUF_FONT_COLORS[override]
        r, g, b = c[1], c[2], c[3]
    end

    if r == nil then
        local color = (RAID_CLASS_COLORS and RAID_CLASS_COLORS[classToken]) or nil
        if color then
            r, g, b = color.r, color.g, color.b
        end
    end
    if r == nil and C_ClassColor and C_ClassColor.GetClassColor then
        local ccObj = C_ClassColor.GetClassColor(classToken)
        if ccObj and ccObj.GetRGB then
            r, g, b = ccObj:GetRGB()
        end
    end

    r, g, b = r or defaultR, g or defaultG, b or defaultB

    if cc then
        cc[classToken] = { r, g, b }
    end
    return r, g, b
end

local function UFCore_RefreshHealthBarColorFast(frame, conf)
    if not frame or not frame.unit or not frame.hpBar then return end
    local unit = frame.unit

    if not UnitExists(unit) then
        return
    end

    -- Make sure the unit-type flags are up to date (pet, player, boss, etc.)
    InitUnitFlags(frame)

    local cache = UFCore_GetSettingsCache()

    -- Only dynamic "class" frames need identity invalidation here.
    -- Dark/unified modes and static class-colored frames (player, pet override) never
    -- change color from UNIT_FACTION / UNIT_FLAGS during combat.
    -- Exception: pet/NPC alive↔dead transitions fire UNIT_FLAGS and must always
    -- refresh the reaction cache so the bar stops showing "dead" grey.
    if frame._msufHealthColorDirty and not frame._msufCachedIsPlayer then
        frame._msufCachedReactionKind = nil
        frame._msufNpcTypeColored = nil
    end
    if not frame._msufStaticHealthColor then
        frame._msufCachedIsPlayer = nil
        frame._msufNpcTypeColored = nil
    end

    -- Bar mode (authoritative): "dark" | "class" | "unified"
    local mode = (cache and cache.barMode) or "dark"

    local barR, barG, barB

    if mode == "dark" then
        barR, barG, barB = cache.darkBarR, cache.darkBarG, cache.darkBarB

    elseif mode == "unified" then
        barR, barG, barB = cache.unifiedBarR, cache.unifiedBarG, cache.unifiedBarB

    else
        -- mode == "class": players = class, NPCs = reaction
        -- P4: read identity cache (avoids UnitIsPlayer + UnitReaction C calls here).
        local isPlayer = frame._msufCachedIsPlayer
        if isPlayer == nil then
            -- cache cold (first color call before DIRTY_IDENTITY ran): populate now.
            _RefreshUnitIdentityCache(frame)
            isPlayer = frame._msufCachedIsPlayer
        end
        if isPlayer then
            local _, classToken = UnitClass(unit)
            barR, barG, barB = UFCore_GetClassBarColorFast(classToken)
        else
            local kind = frame._msufCachedReactionKind or "enemy"
            -- If NPC type coloring is active but bar toggle is off, fall back to "enemy"
            if frame._msufNpcTypeColored and not cache.npcTypeColorBar then
                kind = "enemy"
            end
            barR, barG, barB = UFCore_GetNPCReactionColorFast(kind)
        end

        -- Pet frame override (only when using Class mode)
        if frame._msufIsPet and cache and cache.petFrameColorEnabled then
            barR, barG, barB = cache.petFrameColorR, cache.petFrameColorG, cache.petFrameColorB
        end
    end

    -- Cache to avoid redundant UI work.
    if frame._msufLastHPBarR == barR and frame._msufLastHPBarG == barG and frame._msufLastHPBarB == barB and frame._msufLastHPBarMode == mode then
        return
    end
    frame._msufLastHPBarR, frame._msufLastHPBarG, frame._msufLastHPBarB, frame._msufLastHPBarMode = barR, barG, barB, mode

    frame.hpBar:SetStatusBarColor(barR or 0, barG or 1, barB or 0, 1)

    -- Keep gradients/background in sync if present (cheap + stamp-gated in main code).
    local fnGrad = _G.MSUF_ApplyHPGradient
    if type(fnGrad) == "function" then
        if frame.hpGradients then
            fnGrad(frame)
        elseif frame.hpGradient then
            fnGrad(frame.hpGradient)
        end
    end
    local fnBg = _G.MSUF_ApplyBarBackgroundVisual
    if type(fnBg) == "function" and frame.bg then
        if frame._msufVisualQueuedUFCore or (cache and cache.anyBarBackgroundTracksHPColor) then
            fnBg(frame)
        end
    end
end

Elements.Health = {
    key = "Health",
    bit = EL_HEALTH,
    dirty = DIRTY_HEALTH,
    events = {
        "UNIT_HEALTH", "UNIT_MAXHEALTH",
        "UNIT_ABSORB_AMOUNT_CHANGED", "UNIT_HEAL_ABSORB_AMOUNT_CHANGED",
        "UNIT_HEAL_PREDICTION", "UNIT_MAXHEALTHMODIFIER",
        "UNIT_FACTION", "UNIT_FLAGS",

    },
    Enable = function(f, conf) end,
    Disable = function(f) end,
    Update = function(f, conf)
        local fnH = FN_UpdateHealthFast
        if not fnH then return false end
        local hp = select(1, fnH(f))
        local fnTxt = FN_UpdateHpTextFast
        if fnTxt then fnTxt(f, hp) end
        -- Hard split: value updates every tick; visuals/layout only when requested.
        -- Color refresh is only needed on explicit unit swap/show (visual queue) or
        -- when a reaction/flag event marked it dirty.
        if f._msufVisualQueuedUFCore or f._msufHealthColorDirty then
            f._msufHealthColorDirty = nil
            UFCore_RefreshHealthBarColorFast(f, conf)
        end
        return true
    end,
}

Elements.Power = {
    key = "Power",
    bit = EL_POWER,
    dirty = DIRTY_POWER,
    events = {
        "UNIT_POWER_UPDATE", "UNIT_POWER_FREQUENT", "UNIT_MAXPOWER", "UNIT_DISPLAYPOWER",
        "UNIT_POWER_BAR_SHOW", "UNIT_POWER_BAR_HIDE",
    },
    Enable = function(f, conf) end,
    Disable = function(f)
        -- When the Power element is disabled (power text AND power bar off),
        -- clear/hide both immediately so no stale 'last resource' UI remains.
        if not f then return end

        f._msufLastPwrTextType = nil
        f._msufLastPwrTextCur = nil
        f._msufLastPwrTextMax = nil
        f._msufPwrTextForce = true

        local pt = f.powerText
        if pt then
            local fnSet = FN_SetTextIfChanged
            if fnSet then
                fnSet(pt, "")
            else
                pt:SetText("")
            end
            pt:Hide()
        end

        local bar = f.targetPowerBar or f.powerBar
        if bar then
            bar:SetScript("OnUpdate", nil)
            bar:SetMinMaxValues(0, 1)
            if type(_G.MSUF_SetBarValue) == "function" then
                _G.MSUF_SetBarValue(bar, 0, false)
            else
                bar:SetValue(0)
            end
            bar.MSUF_lastValue = 0
            bar.MSUF_lastPowerToken = nil
            bar.MSUF_lastPowerColor = nil
            bar:Hide()
        end
    end,
    Update = function(f)
        local fnBar = FN_UpdatePowerBarFast
        local fnTxt = FN_UpdatePowerTextFast
        local ok = false

        -- PERF: Only track before/after visibility when a flag indicates a potential
        -- visibility-changing event (UNIT_DISPLAYPOWER, UNIT_POWER_BAR_SHOW/HIDE).
        -- UNIT_MAXPOWER (the main event reaching this path) doesn't change bar visibility.
        local needVisCheck = f._msufPowerVisCheckNeeded
        local beforeBottomIsPower = false
        if needVisCheck then
            f._msufPowerVisCheckNeeded = nil
            local pb = f.targetPowerBar or f.powerBar
            beforeBottomIsPower = (f._msufPowerBarReserved == true) or (pb and pb.IsShown and pb:IsShown()) or false
        end

        if fnBar then fnBar(f); ok = true end

        if needVisCheck then
            local afterBottomIsPower = beforeBottomIsPower
            local pb = f.targetPowerBar or f.powerBar
            afterBottomIsPower = (f._msufPowerBarReserved == true) or (pb and pb.IsShown and pb:IsShown()) or false
            if beforeBottomIsPower ~= afterBottomIsPower then
                if (f and (f._msufBarOutlineThickness or 0) > 0) and type(_G.MSUF_QueueUnitframeVisual) == "function" then
                    _G.MSUF_QueueUnitframeVisual(f)
                end
            end
        end

        if fnTxt then fnTxt(f); ok = true end
        return ok
    end,
}

Elements.Identity = {
    key = "Identity",
    bit = EL_IDENTITY,
    dirty = DIRTY_IDENTITY,
    urgent = true,
    eventMaskOverrides = { UNIT_FACTION = DIRTY_IDENTITY },
    events = {
        "UNIT_NAME_UPDATE", "UNIT_LEVEL",
        "UNIT_CLASSIFICATION_CHANGED", "UNIT_FACTION",
    },
    Enable = function(f, conf) end,
    Disable = function(f) end,
    Update = function(f, conf)
        return UFCore_UpdateIdentityFast(f, conf)
    end,
}

Elements.Portrait = {
    key = "Portrait",
    bit = EL_PORTRAIT,
    dirty = DIRTY_PORTRAIT,
    events = {
        "UNIT_PORTRAIT_UPDATE",
        "UNIT_MODEL_CHANGED",
    },
    Enable = function(f, conf) end,
    Disable = function(f) end,
    Update = function(f, conf)
        local fn = _G.MSUF_MaybeUpdatePortrait or _G.MSUF_UpdatePortraitIfNeeded
        -- PERF: NEVER return false. Returning false triggers legacyFallback → full
        -- UpdateSimpleUnitFrame (0.3-0.5ms). If fn/conf unavailable, skip silently;
        -- portrait will update on next config change or unit swap.
        if type(fn) ~= "function" then return true end
        if not f or not f.portrait then return true end
        if not conf then return true end
        local unit = f.unit
        if not unit then return true end

        -- Performance: ignore UNIT_PORTRAIT_UPDATE / UNIT_MODEL_CHANGED spam for frames that should behave
        -- as "static" or only update once per unit swap.
        --
        -- Player + Boss: static portraits (only touch when explicitly dirty or settings/layout changed).
        -- Target/Focus: update portrait texture only once per swap (handled via GUID change in the main UF update path).
        if (unit == "player" or unit == "target" or unit == "focus" or f.isBoss) and (not f._msufPortraitDirty) then
            local mode = conf.portraitMode or "OFF"
            local render = conf.portraitRender
            if render ~= "3D" and render ~= "CLASS" then
                render = "2D"
            end
            local h = tonumber(conf.height) or (f.GetHeight and f:GetHeight()) or 0
            if (f._msufPortraitModeStamp == mode) and (f._msufPortraitRenderStamp == render) and
               (f._msufPortraitLayoutModeStamp == mode) and (f._msufPortraitLayoutHStamp == h) then
                return true
            end
        end

        local existsForPortrait = UnitExists(unit)
        fn(f, unit, conf, existsForPortrait)
        return true
    end,
}

Elements.Status = {
    key = "Status",
    bit = EL_STATUS,
    dirty = DIRTY_STATUS,
    events = {
        "UNIT_CONNECTION",
        "UNIT_FLAGS",
        -- Incoming resurrection (player/target).
        "INCOMING_RESURRECT_CHANGED",
    },
    -- IMPORTANT PERF POLICY:
    -- UNIT_FLAGS can flood at boss pull (many units flip combat flags at once).
    -- Never allow UNIT_FLAGS to bypass the normal UFCore flush queue, even for
    -- target/focus/ToT which otherwise default-promote to urgent.
    --
    -- This preserves gameplay correctness (status updates still happen), but
    -- prevents large spikes by forcing coalescing + budgeted flush.
    eventUrgentOverrides = {
        UNIT_FLAGS = false,
    },
    Enable = function(f, conf) end,
    Disable = function(f) end,
    Update = function(f, conf)
        return UFCore_UpdateStatusFast(f, conf)
    end,
}

Elements.Indicators = {
    key = "Indicators",
    bit = EL_INDICATOR,
    dirty = DIRTY_INDICATOR,
    -- Driven by global events (GROUP_ROSTER_UPDATE / PARTY_LEADER_CHANGED / RAID_TARGET_UPDATE).
    -- No per-frame unit events here.
    events = nil,
    Enable = function(f, conf) end,
    Disable = function(f)
        if not f then return end
        if f.leaderIcon then f.leaderIcon:Hide() end
        if f.assistantIcon then f.assistantIcon:Hide() end
        if f.raidMarkerIcon then f.raidMarkerIcon:Hide() end
    end,
    Update = function(f, conf)
        if not f then return false end
        local cache = UFCore_GetSettingsCache()
        local unit = f.unit

        if not cache or not cache.generalRef or not unit then
            if f.leaderIcon then f.leaderIcon:Hide() end
            if f.raidMarkerIcon then f.raidMarkerIcon:Hide() end
            if f.assistantIcon then f.assistantIcon:Hide() end
            return true
        end

        -- Leader / Assist icon
        if f.leaderIcon then
            local showAllowed = true
            if conf and conf.showLeaderIcon ~= nil then
                showAllowed = (conf.showLeaderIcon ~= false)
            else
                showAllowed = (cache.showLeaderIconDefault ~= false)
            end

            if not showAllowed then
                f.leaderIcon:Hide()
            else
                local isLeader = UnitIsGroupLeader and UnitIsGroupLeader(unit) and true or false
                local isAssist = (not isLeader) and UnitIsGroupAssistant and UnitIsGroupAssistant(unit) and true or false

                if isLeader then
                    f.leaderIcon:SetTexture("Interface\\GroupFrame\\UI-Group-LeaderIcon")
                    f.leaderIcon:Show()
                elseif isAssist then
                    f.leaderIcon:SetTexture("Interface\\GroupFrame\\UI-Group-AssistantIcon")
                    f.leaderIcon:Show()
                else
                    f.leaderIcon:Hide()
                end
            end
        end

        -- Raid marker icon
        if f.raidMarkerIcon then
            local show = true
            if conf and conf.showRaidMarker ~= nil then
                show = (conf.showRaidMarker ~= false)
            else
                show = (cache.showRaidMarkerDefault ~= false)
            end

            if not show then
                f.raidMarkerIcon:Hide()
            else
                local idx = (GetRaidTargetIndex and GetRaidTargetIndex(unit)) or nil
                -- Midnight/Beta can return idx as a "secret value"; never compare / do math on it.
                if addon and addon.EditModeLib and addon.EditModeLib.IsInEditMode and addon.EditModeLib:IsInEditMode() then
                    idx = idx or 8 -- stable preview while editing
                end
                if idx and SetRaidTargetIconTexture then
                    SetRaidTargetIconTexture(f.raidMarkerIcon, idx)
                    f.raidMarkerIcon:Show()
                else
                    f.raidMarkerIcon:Hide()
                end
            end
        end

        return true
    end,
}

Elements.ToTInline = {
    key = "ToTInline",
    bit = EL_TOTINLINE,
    dirty = DIRTY_TOTINLINE,
    -- Events are driven by the UFCore Global driver (UNIT_TARGET + PLAYER_TARGET_CHANGED),
    -- so we don't register anything on the target frame here.
    events = nil,
    Enable = function(f, conf) end,
    Disable = function(f)
        if not f then return end
        if f._msufToTInlineSep and f._msufToTInlineSep.Hide then f._msufToTInlineSep:Hide() end
        if f._msufToTInlineText and f._msufToTInlineText.Hide then f._msufToTInlineText:Hide() end
    end,
        Update = function(f, conf)
        if not f or not f._msufIsTarget then return false end
        UFCore_UpdateToTInline(f)
        return true
    end,
}

local ELEMENT_LIST = {
    Elements.Health,
    Elements.Power,
    Elements.Identity,
    Elements.Indicators,
    Elements.ToTInline,
    Elements.Portrait,
    Elements.Status,
}

local UFCORE_EVENT_ALIAS = {
    UNIT_HEALTH_FREQUENT = "UNIT_HEALTH",
    -- UNIT_POWER_FREQUENT: intentionally NOT aliased.
    -- Must be registered as its own event for smooth power bars.
    -- DIRECT_APPLY maps it to the same handler as UNIT_POWER_UPDATE.
}

local function UFCore_WantEvent(f, conf, desired, unsupported, ev)
    ev = UFCORE_EVENT_ALIAS[ev] or ev
    if (unsupported and unsupported[ev]) then return end
    if ev == "INCOMING_RESURRECT_CHANGED" then
        if not (conf and conf.showIncomingResIndicator) then return end
    end
    -- UNIT_POWER_FREQUENT: only register on the PLAYER frame when toggles ON.
    -- Target/Focus/Boss never get this event → zero overhead for non-player.
    if ev == "UNIT_POWER_FREQUENT" then
        if not (_smoothPowerBar or _realtimePowerText) then return end
        if not f._msufIsPlayer then return end
    end
    desired[ev] = true
end

-- Ensure the targettarget DB node exists even when the ToT unitframe is disabled.
-- This is required so "ToT inline in target name" works immediately without ever enabling the ToT frame.
function UFCore_GetTargetToTInlineConf()
    local db = UFCore_EnsureDBOnce()
    if type(db) ~= "table" then
        return nil
    end

    -- DB can be swapped on profile import; refresh cache if so.
    if Core._totInlineConfDB ~= db then
        Core._totInlineConfDB = db
        Core._totInlineConfRef = nil
        Core._totInlineConfMigrated = nil
    end

    local tt = Core._totInlineConfRef
    if type(tt) ~= "table" then
        tt = db.targettarget
        if type(tt) ~= "table" then
            tt = {}
            db.targettarget = tt
        end
        Core._totInlineConfRef = tt
    end

    -- One-time migration/defaults (no per-target-switch work).
    if not Core._totInlineConfMigrated then
        -- Migration / alias: older builds may have stored the flag under MSUF_DB.target.
        if tt.showToTInTargetName == nil then
            local t = db.target
            if type(t) == "table" then
                local v = t.showToTInTargetName
                if v == 1 or v == "1" then v = true end
                if v == 0 or v == "0" then v = false end
                if v ~= nil then
                    tt.showToTInTargetName = (v == true)
                end
            end
        end

        -- Migration / alias: older builds may have stored the separator under MSUF_DB.target.
        if tt.totInlineSeparator == nil then
            local t = db.target
            if type(t) == "table" and type(t.totInlineSeparator) == "string" then
                tt.totInlineSeparator = t.totInlineSeparator
            end
        end
        if type(tt.totInlineSeparator) ~= "string" or tt.totInlineSeparator == "" then
            tt.totInlineSeparator = "|"
        end

        if tt.showToTInTargetName == nil then
            tt.showToTInTargetName = false
        end

        Core._totInlineConfMigrated = true
    end

    return tt
end

-- ToT inline is CORE-owned and must never depend on the ToT unitframe being enabled/built.
local function UFCore_IsToTInlineEnabled()
    local conf = UFCore_GetTargetToTInlineConf()
    return (conf and conf.showToTInTargetName == true) and true or false
end

function UFCore_UpdateToTInline(f)
    if not f or not f._msufIsTarget then return end

    if not UFCore_IsToTInlineEnabled() then
        if f._msufToTInlineSep and f._msufToTInlineSep.Hide then f._msufToTInlineSep:Hide() end
        if f._msufToTInlineText and f._msufToTInlineText.Hide then f._msufToTInlineText:Hide() end
        return
    end

    -- Widgets are created/anchored in the layout path (Step 3 policy).
    if (not f._msufToTInlineSep) or (not f._msufToTInlineText) then
        Core.RequestLayout(f, "ToTInlineWidgetsMissing", true)
        return
    end

    local show = false

    local inEdit = false
    if addon and addon.EditModeLib and addon.EditModeLib.IsInEditMode then
        inEdit = addon.EditModeLib:IsInEditMode() and true or false
    end

    if inEdit then
        show = true
        _SetText(f._msufToTInlineText, "ToT")
    else
        if UnitExists and UnitExists("targettarget") then
            show = true
            local nm
            if UnitName then
                nm = UnitName("targettarget")
            end

            -- Secret-safe: do NOT compare/test nm (can be a secret value).
            -- Just set text (nil-safe via `or ""`), no pcall in hot paths.
            _SetText(f._msufToTInlineText, nm or "")
        end
    end

    -- Separator token (stored in DB; render with spaces around it, legacy-style).
    do
        local conf = UFCore_GetTargetToTInlineConf()
        local token = (conf and conf.totInlineSeparator) or "|"
        if type(token) ~= "string" or token == "" then token = "|" end
        _SetText(f._msufToTInlineSep, " " .. token .. " ")
    end

    if show then
        -- Width clamp: cap ToT inline text to ~32% of frame width (secret-safe, no string math).
        local txt = f._msufToTInlineText
        local frameWidth = (f.GetWidth and f:GetWidth()) or 0
        local maxW = 120
        if frameWidth > 0 then
            maxW = math.floor(frameWidth * 0.32)
            if maxW < 80 then maxW = 80 end
            if maxW > 180 then maxW = 180 end
        end
        txt:SetWidth(maxW)

        -- Coloring: class color for players, reaction color for NPCs (secret-safe, no string compares).
        local r, g, b = 1, 1, 1
        if not inEdit then
            if UnitIsPlayer and UnitIsPlayer("targettarget") then
                local cache = UFCore_GetSettingsCache()
                if cache and cache.nameClassColor then
                    local _, classToken = UnitClass("targettarget")
                    r, g, b = UFCore_GetClassBarColorFast(classToken)
                end
            else
                if UnitIsDeadOrGhost and UnitIsDeadOrGhost("targettarget") then
                    r, g, b = UFCore_GetNPCReactionColorFast("dead")
                else
                    local reaction = tonumber(UnitReaction and UnitReaction("player", "targettarget"))
                    if reaction then
                        if reaction >= 5 then
                            r, g, b = UFCore_GetNPCReactionColorFast("friendly")
                        elseif reaction == 4 then
                            r, g, b = UFCore_GetNPCReactionColorFast("neutral")
                        else
                            r, g, b = UFCore_GetNPCReactionColorFast("enemy")
                        end
                    else
                        r, g, b = UFCore_GetNPCReactionColorFast("enemy")
                    end
                end
            end
        end
        f._msufToTInlineSep:SetTextColor(0.7, 0.7, 0.7)
        txt:SetTextColor(r, g, b)

        _SetShown(f._msufToTInlineSep, true)
        _SetShown(txt, true)
    else
        if f._msufToTInlineSep and f._msufToTInlineSep.Hide then f._msufToTInlineSep:Hide() end
        if f._msufToTInlineText and f._msufToTInlineText.Hide then f._msufToTInlineText:Hide() end
    end
end
-- Forward declaration: ComputeElementMask may need to ensure ToT-inline widgets
-- before the local function is defined later in this file (Lua scoping).
local UFCore_EnsureToTInlineWidgets

local function ComputeElementMask(f)
    if not f or not f.unit then
        return 0, nil
    end

    -- Prefer cachedConfig, but fall back to msufConfigKey if present.
    local conf = GetFrameConf(f)

    -- Ensure per-unit flags are available for cheap per-unit gating below.
    -- (No behavior change; flags are purely derived from f.unit.)
    InitUnitFlags(f)

-- Ensure widgets exist even on login/reload order edge-cases (e.g. Name Shortening already enabled).
if conf and conf.showToTInTargetName and (not f._msufToTInlineText or not f._msufToTInlineSep) then
    UFCore_EnsureToTInlineWidgets(f, conf)
end

    -- Disabled frames don't need any unit events.
    if conf and conf.enabled == false then
        return 0, conf
    end

    local mask = 0

    -- HEALTH: enabled when the HP bar and/or HP text is in use (or absorb overlays exist).
    -- We avoid IsShown() here because visibility drivers can temporarily hide the frame.
    local wantHealth = true
    if conf and conf.showHP == false and (f.showHPText == false) and (not f.absorbBar) and (not f.healAbsorbBar) then
        wantHealth = false
    end
    if wantHealth and (f.hpBar or f.absorbBar or f.healAbsorbBar) then
        mask = bor(mask, EL_HEALTH)
    end

    -- POWER:
    -- IMPORTANT: power BAR updates must not depend on the power TEXT toggle.
    -- Some layouts keep the power bar enabled via MSUF_DB.bars.* while using conf.showPower only
    -- as the "power text" toggle. If we disable EL_POWER when the text is off, we accidentally
    -- unregister UNIT_POWER_* events and the bar appears "frozen" on target swaps.
    local hasPowerBarWidget  = (f.targetPowerBar ~= nil) or (f.powerBar ~= nil)
    local hasPowerTextWidget = (f.powerText ~= nil)
    local wantPower = false

    -- If a power bar widget exists, enable POWER updates unless the per-unit power bar toggle
    -- explicitly disables it in bars config.
    if hasPowerBarWidget then
        local cache = UFCore_GetSettingsCache()
        local showForUnit = true

        if cache then
            if f._msufIsPlayer then
                showForUnit = (cache.showPlayerPowerBar ~= false)
            elseif f._msufIsFocus then
                showForUnit = (cache.showFocusPowerBar ~= false)
            elseif f._msufIsTarget then
                showForUnit = (cache.showTargetPowerBar ~= false)
            elseif f.isBoss then
                showForUnit = (cache.showBossPowerBar ~= false)
            end
        end

        if showForUnit then
            wantPower = true
        end
    end

    -- If we don't have a power bar, fall back to legacy behavior for "text-only" power widgets.
    if (not wantPower) and hasPowerTextWidget then
        wantPower = (f.showPowerText ~= false)
    end

    if wantPower then
        mask = bor(mask, EL_POWER)
    end

    -- IDENTITY: name and/or level indicator.
    local wantIdentity = false
    if conf then
        wantIdentity = (conf.showName ~= false) or (conf.showLevelIndicator == true)
    else
        wantIdentity = (f.showName ~= false)
    end
    if wantIdentity then
        mask = bor(mask, EL_IDENTITY)
    end

    -- INDICATORS: leader/assist + raid marker icons (driven by global events)
    if (f.leaderIcon or f.raidMarkerIcon or f.assistantIcon) then
        mask = bor(mask, EL_INDICATOR)
    end

    -- ToT INLINE (Target name extension): only on target frame when enabled.
    if f._msufIsTarget and f.nameText and UFCore_IsToTInlineEnabled() then
        mask = bor(mask, EL_TOTINLINE)
    end

    -- PORTRAIT: only if portrait mode is enabled.
    local pm = conf and conf.portraitMode or "OFF"
    if pm and pm ~= "OFF" and f.portrait then
        mask = bor(mask, EL_PORTRAIT)
    end

    -- STATUS: keep correctness for dead/offline/flags when the frame shows health or status text.
    -- (We treat it as a separate element so it can be gated later if desired.)
    if (mask ~= 0) and (f.statusIndicatorText or f.statusIndicatorOverlayText or f.statusIndicatorOverlayFrame or f.hpBar) then
        mask = bor(mask, EL_STATUS)
    end

    return mask, conf
end

local function RefreshUnitEvents(f, force)
    if not f or not f.unit or not f.RegisterUnitEvent then
        return
    end

    local mask, conf = ComputeElementMask(f)
    local cache = UFCore_GetSettingsCache()
    UFCore_RefreshFrameInvariantFlags(f, cache)
    local last = f._msufElemMask or 0
    if not force and mask == last then
        return
    end

-- Element lifecycle hooks (Enable/Disable) on transitions.
-- (Currently mostly a structure point; events are gated below via `desired`.)
for i = 1, #ELEMENT_LIST do
    local el = ELEMENT_LIST[i]
    local wasOn = (band(last, el.bit) ~= 0)
    local nowOn = (band(mask, el.bit) ~= 0)
    if nowOn and (not wasOn) and el.Enable then
        el.Enable(f, conf)
    elseif wasOn and (not nowOn) and el.Disable then
        el.Disable(f)
    end
end

    f._msufElemMask = mask

    -- oUF-like: do not nuke all events; only add/remove what we own.
    local reg = f._msufUFCoreEvents
    if not reg then
        reg = {}
        f._msufUFCoreEvents = reg
    end

    local desired = Core._scratchDesired
    if not desired then
        desired = {}
        Core._scratchDesired = desired
    else
        wipe(desired)
    end

	-- Cache for unit-event names that are not supported on this client/branch.
	-- (Some beta branches ship with different unit events; RegisterUnitEvent throws on unknown ones.)
	local unsupported = Core._unsupportedUFCoreUnitEvents
	local IsEventValid = (C_EventUtils and C_EventUtils.IsEventValid)

if mask ~= 0 then
    for i = 1, #ELEMENT_LIST do
        local el = ELEMENT_LIST[i]
        if band(mask, el.bit) ~= 0 then
            local evs = el.events
            if evs then
                for j = 1, #evs do
                    local ev = evs[j]
                    UFCore_WantEvent(f, conf, desired, unsupported, ev)
                end
            end
        end
    end
end

	-- Unregister events we no longer need.
	-- Important: unitframes can be externally hard-disabled via UnregisterAllEvents or similar,
	-- which can desync our bookkeeping table. UnregisterEvent() throws in that case.
	for ev in pairs(reg) do
		if not desired[ev] then
			if (not f.IsEventRegistered) or f:IsEventRegistered(ev) then
				f:UnregisterEvent(ev)
			end
			reg[ev] = nil
		end
	end

	-- Register new events we now need.
    if mask ~= 0 then
        for ev in pairs(desired) do
            if not reg[ev] then
                -- All events we register here are unit events (filtered via RegisterUnitEvent).
                -- Global events are routed through the UFCore global driver.
                -- Some events are client/branch-specific; RegisterUnitEvent throws on unknown ones.
                -- Registration is not a hot path, so guard it to avoid hard failures.
                if unsupported and unsupported[ev] then
                    -- Skip unsupported events permanently on this client.
                else
                    if IsEventValid and (not IsEventValid(ev)) then
                        unsupported = unsupported or {}
                        Core._unsupportedUFCoreUnitEvents = unsupported
                        unsupported[ev] = true
                    else
                        f:RegisterUnitEvent(ev, f.unit)
                        reg[ev] = true
                    end
                end
            end
        end
    end
end

-- ------------------------------------------------------------
-- Queue / flush (coalesced)
-- ------------------------------------------------------------

local function NewQueue(withSet)
    return { t = {}, head = 1, tail = 0, size = 0, set = withSet and {} or nil }
end

-- urgent/normal need fast membership checks for promotion (no O(n) scans)
local urgentQueue = NewQueue(true)
local normalQueue = NewQueue(true)
local warmupQueue = NewQueue()
local visualQueue = NewQueue()

local function QueueContains(q, f)
    if not q or not f then return false end
    local set = q.set
    if set then
        return set[f] and true or false
    end
    local t = q.t
    for i = q.head, q.tail do
        if t[i] == f then
            return true
        end
    end
    return false
end

local function QueueRemove(q, f)
    if not q or not f then return false end
    local set = q.set
    if set then
        if set[f] then
            set[f] = nil
            q.size = q.size - 1
            if q.size == 0 then
                wipe(q.t)
                q.head, q.tail = 1, 0
                wipe(set)
            end
            return true
        end
        return false
    end

    local t = q.t
    for i = q.head, q.tail do
        if t[i] == f then
            t[i] = false -- tombstone (PopFirst skips)
            q.size = q.size - 1
            if q.size == 0 then
                wipe(t)
                q.head, q.tail = 1, 0
            end
            return true
        end
    end
    return false
end

local function Enqueue(q, f)
    if not q or not f then return false end
    local set = q.set
    if set then
        if set[f] then
            return false
        end
        set[f] = true
    end
    local t = q.t
    q.tail = q.tail + 1
    t[q.tail] = f
    q.size = q.size + 1
    return true
end

local function MaybeCompactQueue(q)
    -- Compact occasionally to keep indices bounded (order-preserving).
    -- PERF: avoid allocating a new table on every compaction. We swap in a reusable
    -- scratch table per-queue and clear the old array while scanning (no extra passes).
    if q.size == 0 then
        wipe(q.t)
        q.head, q.tail = 1, 0
        if q.set then wipe(q.set) end
        if q._scratch then wipe(q._scratch) end
        return
    end
    if q.head <= 256 then return end
    if q.head <= (q.tail * 0.5) then return end

    local old = q.t
    local new = q._scratch
    if new then
        wipe(new)
    else
        new = {}
    end

    local n = 0
    local set = q.set

    if set then
        for i = q.head, q.tail do
            local v = old[i]
            old[i] = nil
            if v and v ~= false and set[v] then
                n = n + 1
                new[n] = v
            end
        end
        -- Keep size honest: stale entries are dropped.
        q.size = n
    else
        for i = q.head, q.tail do
            local v = old[i]
            old[i] = nil
            if v and v ~= false then
                n = n + 1
                new[n] = v
            end
        end
        -- NOTE: q.size should already equal n.
    end

    q.t = new
    q._scratch = old
    q.head, q.tail = 1, n
end

local FlushEnabled = false

-- PERF: Frame-level time cache. Updated ONCE per OnUpdate by FlushTask.
-- Used by RunUpdate queue processing and _RefreshFrameNow(). 
-- NOTE: DIRECT_APPLY text rate-limiters use GetTime() directly because
-- FlushTask can be idle (DisableFlushIfIdle) while DIRECT_APPLY still fires.
Core._frameNow = 0
-- Serial incremented by FlushTask each render frame. Used by RunUpdate
-- diff-gates, text spec caching, and _RefreshFrameNow staleness detection.
Core._frameNowSerial = 0
local _localFrameSerial = -1

local function _RefreshFrameNow()
    local s = Core._frameNowSerial
    if _localFrameSerial == s then
        -- Same serial = FlushTask didn't run since our last call.
        -- Either (a) same render frame → return cached, or (b) driver idle → one GetTime().
        -- Detect via simple threshold: if cached is >50ms old, refresh.
        local cached = Core._frameNow
        local real = GetTime()
        if (real - cached) > 0.05 then
            Core._frameNow = real
            -- Advance serial so text budget resets even when FlushTask is idle.
            Core._frameNowSerial = s + 1
            _localFrameSerial = s + 1
            return real
        end
        return cached
    end
    -- FlushTask ran (serial advanced) → it already set _frameNow. Use cache.
    _localFrameSerial = s
    return Core._frameNow
end

local function UFCore_FlushTask()
    -- PERF: Cache GetTime() once per render frame. All rate limiters reuse this.
    Core._frameNow = GetTime()
    Core._frameNowSerial = Core._frameNowSerial + 1
    -- Export serial for cross-file cache validation (MSUF_Text.lua uses this).
    _G._MSUF_FrameSerial = Core._frameNowSerial
    -- PERF: Shared frame budget with A2. Track how much time MSUF used this frame.
    local frameStart = debugprofilestop and debugprofilestop() or nil
    _G._MSUF_FrameBudgetStart = frameStart
    Core.Flush(_ufcoreFlushBudgetMs)
    if frameStart then
        _G._MSUF_FrameBudgetUsed = debugprofilestop() - frameStart
    end
end

local function EnsureFallbackDriver()
    local f = Core._fallbackFrame
    if f then
        _G._MSUF_UFCore_FlushFrame = f
        return f
    end
    f = CreateFrame("Frame")
    f:Hide()
    f:SetScript("OnUpdate", UFCore_FlushTask)
    Core._fallbackFrame = f
    _G._MSUF_UFCore_FlushFrame = f
    return f
end

local function RequestFlushNextFrame()
    -- Schedule a UFCore flush for the next frame when something became dirty.
    EnsureFallbackDriver():Show()
end

local function EnsureFlushEnabled()
    if FlushEnabled then return end
    FlushEnabled = true
    EnsureFallbackDriver():Show()
end

local function DisableFlushIfIdle()
    if urgentQueue.size > 0 or normalQueue.size > 0 or warmupQueue.size > 0 or visualQueue.size > 0 then
        return
    end
    FlushEnabled = false
    if Core._fallbackFrame then
        Core._fallbackFrame:Hide()
    end
end

local function _AddDirtyMask(f, mask)
    if not f then return end
    local cur = f._msufDirtyMask or 0
    f._msufDirtyMask = bor(cur, mask)
end

local function PromoteQueuedToUrgent(f)
    if not f then return end
    -- If it's already in urgentQueue, do nothing.
    if QueueContains(urgentQueue, f) then
        return
    end
    -- Remove from normalQueue if present (tombstone, no shifting).
    QueueRemove(normalQueue, f)
    Enqueue(urgentQueue, f)
end

local function QueueFrame(f, urgent)
    if not f then return end

    if f._msufQueuedUFCore then
        -- Escalate to urgent if a later event is urgent (ToT lane etc.).
        if urgent then
            f._msufQueuedUFCoreUrgent = true
            PromoteQueuedToUrgent(f)
            EnsureFlushEnabled()
            RequestFlushNextFrame()
        end
        return
    end

    f._msufQueuedUFCore = true
    f._msufQueuedUFCoreUrgent = urgent or nil

    if urgent then
        Enqueue(urgentQueue, f)
    else
        Enqueue(normalQueue, f)
    end

    EnsureFlushEnabled()
end

-- ------------------------------------------------------------
-- Public API (Step 1: one flush path)
--   External code should only call Core.MarkDirty (or the global wrapper)
--   and NEVER call UpdateSimpleUnitFrame directly.
-- ------------------------------------------------------------

function Core.MarkDirty(f, mask, urgent, reason)
    if not f then return end
    mask = mask or DIRTY_FULL

    -- PERF: Inlined _AddDirtyMask (eliminates function call per event).
    f._msufDirtyMask = bor(f._msufDirtyMask or 0, mask)

    -- Optional debug: only when pre-cached flag is set (ZERO function calls on hot path).
    if _ufcoreDebugDirty then
        f._msufLastDirtyReason = reason or "?"
        f._msufLastDirtyMask = mask
        f._msufLastDirtyAt = debugprofilestop and debugprofilestop() or 0
    end

    -- Urgent lane policy: default urgent for target/ToT (and focus) if caller didn't specify.
    if urgent == nil then
        urgent = (f._msufIsTarget or f._msufIsToT or f._msufIsFocus) and true or false
    end

    -- PERF: Inlined QueueFrame + PromoteQueuedToUrgent (3 function calls → 0).
    -- This is the single most-called function in the addon (~200-500 calls/sec in raids).
    if f._msufQueuedUFCore then
        if urgent then
            f._msufQueuedUFCoreUrgent = true
            -- Inlined PromoteQueuedToUrgent: single set-check instead of
            -- QueueContains (hash) + QueueRemove (hash) as separate calls.
            local uset = urgentQueue.set
            if not (uset and uset[f]) then
                QueueRemove(normalQueue, f)
                Enqueue(urgentQueue, f)
            end
            if not FlushEnabled then
                FlushEnabled = true
                EnsureFallbackDriver():Show()
            end
        end
        return
    end

    f._msufQueuedUFCore = true
    f._msufQueuedUFCoreUrgent = urgent or nil

    if urgent then
        Enqueue(urgentQueue, f)
    else
        Enqueue(normalQueue, f)
    end

    if not FlushEnabled then
        FlushEnabled = true
        EnsureFallbackDriver():Show()
    end
end

-- ------------------------------------------------------------
-- Step 3: "No layout in runtime"
--  - All ClearAllPoints/SetPoint/SetWidth/SetFont/etc should happen ONLY via this path:
--      * Options Apply
--      * Frame size changes (OnSizeChanged)
--      * Portrait mode changes
--      * hpTextSpacer changes
--  - Runtime unit events (health/power/name/flags) must remain layout-free.
-- ------------------------------------------------------------

function UFCore_EnsureToTInlineWidgets(f, conf)
    if not conf or not conf.showToTInTargetName then return end

    local name = f.nameText
    if not name then return end

    -- ToT-Inline must NOT be parented to the name clip/mask container. Keep it in a dedicated overlay
    -- container on the unitframe so Name Shortening can never hide/clip it.
    local overlay = f._msufToTInlineOverlay
    if not overlay then
        overlay = CreateFrame("Frame", nil, f)
        f._msufToTInlineOverlay = overlay
        overlay:SetAllPoints(f)
        overlay:SetFrameLevel((f:GetFrameLevel() or 0) + 80)
    else
        if overlay:GetParent() ~= f then
            overlay:SetParent(f)
            overlay:SetAllPoints(f)
        end
        local desiredLevel = (f:GetFrameLevel() or 0) + 80
        if overlay:GetFrameLevel() < desiredLevel then
            overlay:SetFrameLevel(desiredLevel)
        end
    end

    local created = false

    local sep = f._msufToTInlineSep
    if not sep then
        sep = overlay:CreateFontString(nil, "OVERLAY")
        f._msufToTInlineSep = sep
        sep:SetFontObject(GameFontNormalSmall)
        sep:SetJustifyH("LEFT")
        sep:SetJustifyV("MIDDLE")
        created = true
    else
        if sep:GetParent() ~= overlay then
            sep:SetParent(overlay)
        end
    end

    local tt = f._msufToTInlineText
    if not tt then
        tt = overlay:CreateFontString(nil, "OVERLAY")
        f._msufToTInlineText = tt
        tt:SetFontObject(GameFontNormalSmall)
        tt:SetJustifyH("LEFT")
        tt:SetJustifyV("MIDDLE")
        created = true
    else
        if tt:GetParent() ~= overlay then
            tt:SetParent(overlay)
        end
    end

    -- Ensure ToT-Inline renders above the Name Shortening overlay (sublevel must be within -128..127).
    sep:SetDrawLayer("OVERLAY", 7)
    tt:SetDrawLayer("OVERLAY", 7)

    sep:ClearAllPoints()
    sep:SetPoint("LEFT", name, "RIGHT", 0, 0)

    tt:ClearAllPoints()
    tt:SetPoint("LEFT", sep, "RIGHT", 0, 0)

    -- Immediately inherit font from nameText (master) so the widgets never
    -- flash with the wrong GameFontNormalSmall size.  Invalidate _msufFontRev
    -- so the central font system re-applies cleanly on the next pass.
    if created and name.GetFont then
        local font, size, flags = name:GetFont()
        if font then
            sep:SetFont(font, size, flags)
            tt:SetFont(font, size, flags)
            sep._msufFontRev = nil
            tt._msufFontRev = nil
        end
    end

    sep:Hide()
    tt:Hide()
end

local function UFCore_ApplyLayout(frame, conf, why)
    if not frame then return end
    if not (FN_EnsureDB and FN_ClampNameWidth and FN_ApplyLeaderIconLayout and FN_ApplyRaidMarkerLayout) then UFCore_ResolveFastFns() end
    local fn = FN_EnsureDB; if fn then fn() end
    -- ToT inline widgets are part of the target text layout (must exist even when the ToT unitframe is disabled).
    UFCore_EnsureToTInlineWidgets(frame, conf)

    fn = FN_ClampNameWidth; if fn then fn(frame, conf) end
    fn = FN_ApplyLeaderIconLayout; if fn then fn(frame) end
    fn = FN_ApplyRaidMarkerLayout; if fn then fn(frame) end

    -- Future: centralize any other SetPoint/SetFont/SetSize logic here.
end

Core.ApplyLayout = UFCore_ApplyLayout

function Core.RequestLayout(f, reason, urgent)
    if not f then return end
    -- capture why (useful for debugging)
    f._msufLayoutWhy = reason or "LAYOUT"
    -- Combat safety: defer layout application until combat ends.
    if _G.MSUF_InCombat then
        local set = Core._layoutDeferredSet
        if not set then
            set = {}
            Core._layoutDeferredSet = set
        end
        set[f] = true
        f._msufLayoutDeferredUrgent = (urgent == true) and true or nil
        f._msufDirtyMask = bor(f._msufDirtyMask or 0, DIRTY_LAYOUT)
        return
    end
    Core.MarkDirty(f, DIRTY_LAYOUT, urgent, reason or "LAYOUT")
end

function _G.MSUF_UFCore_RequestLayout(f, reason, urgent)
    Core.RequestLayout(f, reason, urgent)
end

function _G.MSUF_UFCore_RequestLayoutForUnit(unit, reason, urgent)
    local f = unit and FramesByUnit[unit]
    if not f then return end
    Core.RequestLayout(f, reason or ("LAYOUT:" .. unit), urgent)
end

function Core.RequestFlush()
    EnsureFlushEnabled()
end

function Core.FlushBudgeted(budgetMs)
    Core.Flush(budgetMs)
end

function _G.MSUF_UFCore_MarkDirty(f, mask, urgent, reason)
    Core.MarkDirty(f, mask, urgent, reason)
end

-- Legacy entrypoints used across the addon (keep names stable)
function _G.MSUF_QueueUnitframeUpdate(f, force)
    if not f then return end
    local mask = force and DIRTY_FULL or (DIRTY_HEALTH + DIRTY_POWER + DIRTY_IDENTITY + DIRTY_PORTRAIT + DIRTY_STATUS + DIRTY_INDICATOR + DIRTY_TOTINLINE)
    Core.MarkDirty(f, mask, true, force and "FORCE" or "LEGACY_QUEUE")
end

function _G.MSUF_ScheduleWarmupFrame(f)
    if not f or f._msufWarmupQueuedUFCore then return end
    f._msufWarmupQueuedUFCore = true
    Enqueue(warmupQueue, f)
    EnsureFlushEnabled()
end

function _G.MSUF_QueueUnitframeVisual(f)
    if not f or f._msufVisualQueuedUFCore then return end
    f._msufVisualQueuedUFCore = true
    Enqueue(visualQueue, f)
    EnsureFlushEnabled()
end

-- Defer swap-heavy work to the next frame:
--  - Portrait/model updates can be expensive on PLAYER_TARGET_CHANGED / PLAYER_FOCUS_CHANGED.
--  - Rare bar visuals (colors/gradients/background) are queued into the Visual lane.
local After0 = _G.C_Timer and _G.C_Timer.After

-- Coalesce swap defers to a single next-frame callback (avoid per-swap closures/timers).
Core._swapDeferCoalesce = Core._swapDeferCoalesce or {
    queued = false,
    frames = {},
    portrait = {},
    visual = {},
    why = nil,
}

local function _SwapDeferFlush()
    local sd = Core._swapDeferCoalesce
    if not sd then return end

    sd.queued = false
    local frames = sd.frames
    local portrait = sd.portrait
    local visual = sd.visual
    local why = sd.why
    sd.why = nil

    for f in pairs(frames) do
        frames[f] = nil
        local wantPortrait = portrait[f]
        local wantVisual = visual[f]
        portrait[f] = nil
        visual[f] = nil

        if f then
            f._msufSwapDeferPending = nil
            if f:IsVisible() or f.MSUF_AllowHiddenEvents then
                if wantPortrait then
                    Core.MarkDirty(f, DIRTY_PORTRAIT, false, why or "SWAP_DEFER_PORTRAIT")
                end
                if wantVisual then
                    _G.MSUF_QueueUnitframeVisual(f)
                end
            end
        end
    end
end

local function DeferSwapWork(unit, why, wantPortrait, wantVisual)
    if not After0 or not unit then return end

    local f = FramesByUnit[unit]
    if not f then return end

    -- Unit swaps can change absorb/heal-absorb instantly; mark overlays dirty.
    f._msufAbsorbDirty = true
    f._msufHealAbsorbDirty = true
    f._msufAbsorbTextDirty = true
    f._msufAbsorbInit = nil
    f._msufHealAbsorbInit = nil
    -- Invalidate health diff-gate cache (new unit = new hp/maxHP).
    f._msufFlushHP = nil
    f._msufFlushMaxHP = nil

    local sd = Core._swapDeferCoalesce
    if not sd then return end

    sd.frames[f] = true
    if wantPortrait then
        sd.portrait[f] = true
    end
    if wantVisual ~= false then
        sd.visual[f] = true
    end
    sd.why = why or sd.why

    -- Only schedule one next-frame flush.
    if f._msufSwapDeferPending then
        return
    end
    f._msufSwapDeferPending = true

    if sd.queued then
        return
    end

    sd.queued = true
    After0(0, _SwapDeferFlush)
end

-- ------------------------------------------------------------
-- Flush
-- ------------------------------------------------------------

local function PopFirst(q)
    if not q or q.size == 0 then return nil end
    local t = q.t
    local h = q.head
    local set = q.set

    while h <= q.tail do
        local v = t[h]
        t[h] = nil
        h = h + 1
        if v and v ~= false then
            if set then
                if set[v] then
                    set[v] = nil
                    q.head = h
                    q.size = q.size - 1
                    -- PERF: Inline compaction early-exit (avoids function call per pop).
                    -- MaybeCompactQueue only does work when head > 256 AND head > tail*0.5.
                    if h > 256 then MaybeCompactQueue(q) end
                    return v
                end
            else
                q.head = h
                q.size = q.size - 1
                if h > 256 then MaybeCompactQueue(q) end
                return v
            end
        end
    end

    -- Safety reset (shouldn't happen unless size desync).
    wipe(t)
    if set then wipe(set) end
    q.head, q.tail, q.size = 1, 0, 0
    return nil
end

local function AfterLegacyFullUpdate(f)
    if not f then return end
    if f._msufIsTarget and UFCore_IsToTInlineEnabled() then
        UFCore_UpdateToTInline(f)
    end
    RefreshUnitEvents(f, false)
end

-- Apply dispatch (spec-driven): keeps the hotpath small and avoids repeated mask/conf boilerplate.
local APPLY_STEPS = {
    { mask = DIRTY_HEALTH,    fn = Elements.Health.Update },
    { mask = DIRTY_POWER,     fn = Elements.Power.Update },
    { mask = DIRTY_IDENTITY,  fn = Elements.Identity.Update,    needsConf = true },
    { mask = DIRTY_INDICATOR, fn = Elements.Indicators.Update,  needsConf = true },
    { mask = DIRTY_TOTINLINE, fn = Elements.ToTInline.Update,   needsConf = true },
    { mask = DIRTY_STATUS,    fn = Elements.Status.Update,      needsConf = true },
    { mask = DIRTY_THREAT,    fn = UFCore_UpdateThreatFast },  -- PERF: threat-only (alpha + aggro border)
    { mask = DIRTY_PORTRAIT,  fn = Elements.Portrait.Update,    needsConf = true, legacyFallback = true },
}

local APPLY_MASK, APPLY_NEEDS_CONF_MASK = 0, 0
do
    for i = 1, #APPLY_STEPS do
        local s = APPLY_STEPS[i]
        APPLY_MASK = bor(APPLY_MASK, s.mask)
        if s.needsConf then
            APPLY_NEEDS_CONF_MASK = bor(APPLY_NEEDS_CONF_MASK, s.mask)
        end
    end
end

local function RunUpdate(f)
    if not f then return end
    f._msufQueuedUFCore = nil
    local mask = f._msufDirtyMask or 0
    f._msufDirtyMask = 0

    -- Bridge: the main unitframe renderer only touches the portrait texture when
    -- frame._msufPortraitDirty is set. Our element core uses UNIT_PORTRAIT_UPDATE /
    -- UNIT_MODEL_CHANGED to mark DIRTY_PORTRAIT, so translate that into the legacy
    -- per-frame flag here (secret-safe: no GUID/name comparisons).
    if mask ~= 0 and band(mask, DIRTY_PORTRAIT) ~= 0 then
        f._msufPortraitDirty = true
        f._msufPortraitNextAt = 0
    end

    -- PERF: DIRTY_HEALTH-only fast path (~80% of queued RunUpdate calls in steady combat).
    -- Skips: portrait bridge, layout check, _G.UpdateSimpleUnitFrame resolve, DIRTY_VISUAL
    -- check, APPLY_STEPS loop iteration, conf resolution. Direct-inlined Element.Health.Update.
    -- Zero regression: identical logic to APPLY_STEPS[1] but without dispatch overhead.
    -- Secret-safe: no value comparisons, passes through to existing fast helpers.
    if mask == DIRTY_HEALTH then
        local fnH = FN_UpdateHealthFast
        if fnH then
            local hp = select(1, fnH(f))
            local fnTxt = FN_UpdateHpTextFast
            if fnTxt then fnTxt(f, hp) end
            if f._msufVisualQueuedUFCore or f._msufHealthColorDirty then
                f._msufHealthColorDirty = nil
                UFCore_RefreshHealthBarColorFast(f)
            end
        end
        return
    end

    -- PERF: DIRTY_POWER-only fast path (second most common queued mask).
    -- Same principle: skip all dispatch overhead for pure power updates.
    if mask == DIRTY_POWER then
        local fnBar = FN_UpdatePowerBarFast
        local fnTxt = FN_UpdatePowerTextFast
        if fnBar then fnBar(f) end
        if fnTxt then fnTxt(f) end
        return
    end

    -- Step 3: layout changes are applied only when explicitly requested (DIRTY_LAYOUT),
    -- never as a side-effect of runtime unit events.
    if mask ~= 0 and band(mask, DIRTY_LAYOUT) ~= 0 then
        -- Combat safety: do not apply layout while in combat. Keep the bit pending
        -- and re-apply immediately on PLAYER_REGEN_ENABLED.
        if _G.MSUF_InCombat then
            Core._layoutDeferredSet[f] = true
            f._msufDirtyMask = bor(f._msufDirtyMask or 0, DIRTY_LAYOUT)
            mask = band(mask, bnot(DIRTY_LAYOUT))
            if mask == 0 then
                return
            end
        else
            local conf = GetFrameConf(f)
            Core.ApplyLayout(f, conf, f._msufLayoutWhy or "DIRTY_LAYOUT")
            f._msufLayoutWhy = nil
            mask = band(mask, bnot(DIRTY_LAYOUT))
            if mask == 0 then
                return
            end
        end
    end

    local upd = FN_UpdateSimpleUnitFrame
    if not upd then
        upd = _G.UpdateSimpleUnitFrame
        if upd then FN_UpdateSimpleUnitFrame = upd end
        if not upd then return end
    end

    -- Step 2: element-style updates (spec-driven dispatch; minimal + layout-free).

    -- DIRTY_VISUAL: refresh rare visuals (outline/background/gradients) without
    -- forcing a legacy full update + layout. This is the main source of large spikes
    -- on TARGET/FOCUS acquire (frames were hidden  OnShow + UNIT_SWAP).
    if mask ~= 0 and band(mask, DIRTY_VISUAL) ~= 0 then
        -- PERF: Cached at file scope (stable after init).
        local fn = FN_RefreshRareBarVisuals
        if not fn then
            fn = _G.MSUF_RefreshRareBarVisuals
            if type(fn) ~= "function" then fn = _G.MSUF_ApplyRareVisuals end
            if type(fn) == "function" then FN_RefreshRareBarVisuals = fn end
        end
        if fn then
            fn(f)
        else
            -- Fallback for older builds: keep correctness.
            upd(f)
            AfterLegacyFullUpdate(f)
            return
        end
        mask = band(mask, bnot(DIRTY_VISUAL))
        if mask == 0 then
            return
        end
    end

        if mask ~= 0 and band(mask, bnot(APPLY_MASK)) == 0 then
        local conf
        if band(mask, APPLY_NEEDS_CONF_MASK) ~= 0 then
            conf = GetFrameConf(f)
        end

        for i = 1, #APPLY_STEPS do
            local s = APPLY_STEPS[i]
            if band(mask, s.mask) ~= 0 then
                if s.legacyFallback then
                    if not s.fn(f, conf) then
                        if upd then upd(f) end
                    end
                else
                    s.fn(f, conf)
                end
                -- PERF: Early exit when all dirty bits consumed (common: 1-2 bits set).
                mask = band(mask, bnot(s.mask))
                if mask == 0 then break end
            end
        end

        return
    end

    -- Any other dirty bit: keep correctness by using the legacy full update.
    upd(f)
    AfterLegacyFullUpdate(f)
end -- RunUpdate

local function RunWarmup(f)
    if not f then return end
    f._msufWarmupQueuedUFCore = nil
    local upd = FN_UpdateSimpleUnitFrame or _G.UpdateSimpleUnitFrame
    if upd then
        upd(f)
        AfterLegacyFullUpdate(f)
    end
end

local function RunVisual(f)
    if not f then return end
    f._msufVisualQueuedUFCore = nil
    local fn = FN_RefreshRareBarVisuals or _G.MSUF_RefreshRareBarVisuals
    if fn then
        fn(f)
    else
        -- Fallback: full update if helper not exported yet.
        local upd = FN_UpdateSimpleUnitFrame or _G.UpdateSimpleUnitFrame
        if upd then
            upd(f)
            AfterLegacyFullUpdate(f)
        end
    end
end

-- PERF: UFCore_BudgetOk inlined into Core.Flush (was a function call per loop iteration).
-- Kept as dead code reference for clarity:
-- local function UFCore_BudgetOk(endAt) return (not endAt) or (debugprofilestop() <= endAt) end

function Core.Flush(budgetMs)
    local start = debugprofilestop and debugprofilestop() or nil
    local endAt = (start and budgetMs) and (start + budgetMs) or nil
    -- PERF: Bump settings cache serial so UFCore_GetSettingsCache skips DB-ref
    -- validation on repeated calls within this flush cycle.
    Core._flushSettingsCacheSerial = (Core._flushSettingsCacheSerial or 0) + 1

    local budgetHit = false

    -- Lane policy:
    --   1) Urgent lane is drained first, but is still budgeted to cap spikes.
    --   2) Normal/Warmup/Visual are budgeted to avoid spikes.
    -- PERF: Use file-scope cached urgent max (no UFCore_GetSettingsCache call).
    local URGENT_MAX_PER_FLUSH = _ufcoreUrgentMax
    local urgentCount = 0
    while urgentQueue.size > 0 do
        RunUpdate(PopFirst(urgentQueue))
        urgentCount = urgentCount + 1

        if urgentCount >= URGENT_MAX_PER_FLUSH then
            if urgentQueue.size > 0 then
                budgetHit = true
            end
            break
        end

        -- PERF: Inlined UFCore_BudgetOk (eliminates function call + closure per iteration).
        if endAt and debugprofilestop() > endAt then
            budgetHit = true
            break
        end
    end

    while (not budgetHit) and normalQueue.size > 0 do
        if endAt and debugprofilestop() > endAt then budgetHit = true; break end
        RunUpdate(PopFirst(normalQueue))
    end

    while (not budgetHit) and warmupQueue.size > 0 do
        if endAt and debugprofilestop() > endAt then budgetHit = true; break end
        RunWarmup(PopFirst(warmupQueue))
    end

    while (not budgetHit) and visualQueue.size > 0 do
        if endAt and debugprofilestop() > endAt then budgetHit = true; break end
        RunVisual(PopFirst(visualQueue))
    end

    -- If we still have work, schedule another flush ASAP (next frame / next UM kick).
    if budgetHit and (urgentQueue.size > 0 or normalQueue.size > 0 or warmupQueue.size > 0 or visualQueue.size > 0) then
        RequestFlushNextFrame()
    end

    DisableFlushIfIdle()
end

-- ------------------------------------------------------------
-- Unitframe event routing
-- ------------------------------------------------------------

local UNIT_EVENT_MAP = {}
do
    for i = 1, #ELEMENT_LIST do
        local el = ELEMENT_LIST[i]
        local evs = el.events
        if evs then
            local baseMask, baseUrgent = el.dirty, el.urgent
            local mo = el.eventMaskOverrides
            local uo = el.eventUrgentOverrides
            for j = 1, #evs do
                local ev = evs[j]
                ev = UFCORE_EVENT_ALIAS[ev] or ev
                local m = (mo and mo[ev]) or baseMask
                local info = UNIT_EVENT_MAP[ev]
                if info then
                    info.mask = bor(info.mask, m)
                else
                    info = { mask = m }
                    UNIT_EVENT_MAP[ev] = info
                end

                -- Urgent policy (per-event override supported):
                --   * Explicit false forces non-urgent, even if other callers
                --     would default-promote (e.g. target/focus/ToT policy).
                --   * Explicit true forces urgent.
                --   * Otherwise, element-level urgent=true marks event as urgent.
                local u = (uo and uo[ev])
                if u == false then
                    info.urgent = false
                elseif u == true then
                    info.urgent = true
                elseif baseUrgent then
                    if info.urgent ~= false then
                        info.urgent = true
                    end
                end
            end
        end
    end
    -- Compatibility: other modules may register this event.
    UNIT_EVENT_MAP.UNIT_THREAT_SITUATION_UPDATE = { mask = DIRTY_THREAT }
end

-- ============================================================================
-- Phase 6: Direct-Apply — flattened hot-path for Health / Power.
-- These skip the queue entirely and update in the SAME frame as the event.
-- UNIT_FACTION (Health+Identity) and UNIT_FLAGS (Health+Status) stay on the queue.
--
-- ARCHITECTURE vs oUF:
-- oUF runs Color + Absorb + HealPrediction + PredictionSize on EVERY UNIT_HEALTH.
-- MSUF splits the path:
--   _HealthValueFast  — UNIT_HEALTH only (most frequent: 10-50/sec per unit)
--                       Inlined: 1 C-API + 1 widget call + text. No indirection.
--   _HealthFullFast   — UNIT_MAXHEALTH, absorb, heal-prediction, maxHP-modifier
--                       Full chain: SetMinMaxValues + value + absorb dirty + text.
-- Color updates are NEVER on this path (dirty-flag gated in Elements.Health.Update).
-- ============================================================================

-- _HealthValueFast: absolute minimum for UNIT_HEALTH.
-- Call chain: FrameOnEvent → _HealthValueFast (1 hop, vs 7 hops before).
-- No UnitExists check: unit events guarantee the unit exists.
-- No type() checks: UnitHealth always returns a number.
-- No SetMinMaxValues: maxHP doesn't change on UNIT_HEALTH.
-- No absorb overlay: absorb amount doesn't change on UNIT_HEALTH.
local function _HealthValueFast(f)
    local bar = f.hpBar
    if not bar then return end
    local hp = UnitHealth(f.unit)       -- upvalue (line 21), no F.table lookup
    bar:SetValue(hp)                    -- ALWAYS: direct widget call (~3μs, visually critical)
    -- Text rate-limited to 10Hz per unit (100ms interval). Skipped events are
    -- not a problem: bar:SetValue already shows current HP, text catches up next pass.
    local fnTxt = FN_UpdateHpTextFast
    if fnTxt then
        -- GetTime() required: Core._frameNow freezes when FlushTask is idle
        -- (DisableFlushIfIdle hides the OnUpdate frame). DIRECT_APPLY events
        -- bypass the queue, so FlushTask never restarts. One GetTime() per
        -- UNIT_HEALTH event (~10-50/sec per unit) is negligible.
        -- Rate-limiter alone caps at 10Hz per unit = sufficient budget.
        local now = GetTime()
        if (now - (f._msufHpTxtAt or 0)) >= 0.10 then
            f._msufHpTxtAt = now
            fnTxt(f, hp)
        end
    end
end

-- _HealthFullFast: for non-UNIT_HEALTH events (UNIT_MAXHEALTH, absorb, prediction).
-- These fire much less frequently (~1-10/sec total vs 10-50/sec for UNIT_HEALTH).
-- Uses the existing Elements.Health.Update which correctly handles:
--   SetMinMaxValues, absorb dirty overlays, heal prediction, color dirty, text.
local _HealthFullFast = Elements.Health and Elements.Health.Update

local DIRECT_APPLY = {}
local _IdentityFast
local _StatusFast
local _IndicatorFast
local _RunIdentityDirect
local _RunStatusDirect
do
    local _MaskIdentityHealth = bor(DIRTY_IDENTITY, DIRTY_HEALTH)
    _IdentityFast = Elements.Identity and Elements.Identity.Update
    _StatusFast = Elements.Status and Elements.Status.Update
    _IndicatorFast = Elements.Indicators and Elements.Indicators.Update

    function _RunIdentityDirect(f, fallbackMask, fallbackReason)
        if not _IdentityFast then
            Core.MarkDirty(f, fallbackMask or DIRTY_IDENTITY, nil, fallbackReason or "IDENTITY_DIRECT_MISSING")
            return
        end
        local conf = GetFrameConf(f)
        if not _IdentityFast(f, conf) then
            Core.MarkDirty(f, fallbackMask or DIRTY_IDENTITY, nil, fallbackReason or "IDENTITY_DIRECT_FALLBACK")
        end
    end

    function _RunStatusDirect(f, fallbackMask, fallbackReason)
        if not _StatusFast then
            Core.MarkDirty(f, fallbackMask or DIRTY_STATUS, nil, fallbackReason or "STATUS_DIRECT_MISSING")
            return
        end
        local conf = GetFrameConf(f)
        if not _StatusFast(f, conf) then
            Core.MarkDirty(f, fallbackMask or DIRTY_STATUS, nil, fallbackReason or "STATUS_DIRECT_FALLBACK")
        end
    end

    local function _RunFactionDirect(f)
        local conf = GetFrameConf(f)
        if _IdentityFast then
            if not _IdentityFast(f, conf) then
                Core.MarkDirty(f, _MaskIdentityHealth, nil, "UNIT_FACTION_DIRECT_FALLBACK")
                return
            end
        else
            Core.MarkDirty(f, _MaskIdentityHealth, nil, "UNIT_FACTION_DIRECT_MISSING")
            return
        end

        if f._msufHealthColorDirty then
            f._msufHealthColorDirty = nil
            UFCore_RefreshHealthBarColorFast(f, conf)
        end
    end

    -- UNIT_HEALTH → value-only fast path (most frequent event).
    -- Eliminates: UnitExists check, SetMinMaxValues, type() guards,
    -- ns.Bars.ApplySpec dispatch, MSUF_SetBarValue wrapper.
    DIRECT_APPLY["UNIT_HEALTH"] = _HealthValueFast

    -- Identity/status cheap lane: keep these out of the generic dirty queue.
    -- Falls back to the normal UFCore path when legacy behavior is required
    -- (e.g. boss test mode identity labels).
    if _IdentityFast then
        DIRECT_APPLY["UNIT_NAME_UPDATE"] = function(f)
            _RunIdentityDirect(f, DIRTY_IDENTITY, "UNIT_NAME_UPDATE_DIRECT")
        end
        DIRECT_APPLY["UNIT_LEVEL"] = function(f)
            _RunIdentityDirect(f, DIRTY_IDENTITY, "UNIT_LEVEL_DIRECT")
        end
        -- UNIT_FACTION is the cheap combined case: identity refresh + health color.
        -- UNIT_FLAGS stays queued on purpose because it can flood at boss pull.
        DIRECT_APPLY["UNIT_FACTION"] = _RunFactionDirect
    end

    if _StatusFast then
        DIRECT_APPLY["UNIT_CONNECTION"] = function(f)
            _RunStatusDirect(f, DIRTY_STATUS, "UNIT_CONNECTION_DIRECT")
        end
    end

    -- All other health events → full path (includes range + overlays).
    -- These fire 5-50x less often than UNIT_HEALTH, so the 7-hop chain is acceptable.
    if _HealthFullFast then
        DIRECT_APPLY["UNIT_MAXHEALTH"]                    = _HealthFullFast
        DIRECT_APPLY["UNIT_ABSORB_AMOUNT_CHANGED"]        = _HealthFullFast
        DIRECT_APPLY["UNIT_HEAL_ABSORB_AMOUNT_CHANGED"]   = _HealthFullFast
        DIRECT_APPLY["UNIT_HEAL_PREDICTION"]              = _HealthFullFast
        DIRECT_APPLY["UNIT_MAXHEALTHMODIFIER"]            = _HealthFullFast
    end

    local powerFn = Elements.Power and Elements.Power.Update
    if powerFn then
        -- ──────────────────────────────────────────────────────────────
        -- Power fast-path — MidnightRogueBars EnergyBar approach.
        --
        -- Two independent settings (cached upvalues):
        --
        --   _smoothPowerBar (bars.smoothPowerBar):
        --     ON:  ExponentialEaseOut on SetMinMaxValues + SetValue
        --     OFF: Instant snap (no interpolation)
        --
        --   _realtimePowerText (bars.realtimePowerText):
        --     ON:  Text updated every event (like MidnightRogueBars)
        --     OFF: Budget-gated (player 33Hz, others 10Hz)
        --
        -- UNIT_POWER_FREQUENT is registered for smooth sub-tick updates.
        -- ──────────────────────────────────────────────────────────────
        local _UnitPower     = UnitPower
        local _UnitPowerMax  = UnitPowerMax
        local _UnitPowerType = UnitPowerType
        local _Interp = (type(Enum) == "table"
            and Enum.StatusBarInterpolation
            and Enum.StatusBarInterpolation.ExponentialEaseOut) or nil

        -- PERF: Pre-resolve UnitPowerPercent + ScaleTo100 for RenderPowerText cache.
        -- Caching pPct here eliminates 1 UnitPowerPercent C-API call per text update.
        local _PwrPctFn = UnitPowerPercent
        local _PwrScale = (type(CurveConstants) == "table" and CurveConstants.ScaleTo100) or true

        local function _MaybeUpdatePowerText(f, unit, pType, cur, mx, budget)
            local fnTxt = FN_UpdatePowerTextFast
            if not fnTxt then return end
            if budget then
                local now = GetTime()
                if (now - (f._msufPwrTxtAt or 0)) < budget then return end
                f._msufPwrTxtAt = now
            end
            if UFCore_SamePowerTextSnapshot(f, pType, cur, mx) then return end
            UFCore_StorePowerTextSnapshot(f, pType, cur, mx)
            if _PwrPctFn then f._msufCachedPPct = _PwrPctFn(unit, pType, false, _PwrScale) end
            fnTxt(f)
        end

        -- ── Handler A: Both OFF — zero added overhead vs original MSUF ──
        -- No interpolation, budget-gated text. No function calls for time check.
        local function _PowerOff(f)
            local bar = f.targetPowerBar or f.powerBar
            if not bar then return end

            local unit = f.unit
            local pType = _UnitPowerType(unit)
            if pType == nil then return end
            -- Ele Shaman: class power shows Maelstrom → main bar shows Mana
            if f._msufIsPlayer and _G.MSUF_EleMaelstromActive then pType = 0 end
            -- Aug Evoker: class power shows Ebon Might → main bar shows Essence
            if f._msufIsPlayer and _G.MSUF_AugEvokerActive then pType = 19 end
            if f._msufIsPlayer and _G.MSUF_ShadowManaActive then pType = 0 end

            local cur = _UnitPower(unit, pType)
            local mx  = _UnitPowerMax(unit, pType)
            -- SECRET-SAFE: == nil is a reference check (no taint). Secret numbers
            -- pass through to SetMinMaxValues/SetValue fine (widget handles internally).
            if cur == nil then cur = 0 end
            if mx  == nil then mx  = 100 end

            if UFCore_SamePowerSnapshot(f, pType, cur, mx) then return end

            bar:SetMinMaxValues(0, mx)
            bar:SetValue(cur)

            UFCore_StorePowerSnapshot(f, pType, cur, mx)

            -- Budget-gated text: GetTime() inside _MaybeUpdatePowerText ensures
            -- correct rate-limiting even when FlushTask is idle (DIRECT_APPLY path).
            _MaybeUpdatePowerText(f, unit, pType, cur, mx, (f._msufIsPlayer and 0.03) or 0.10)
        end

        -- ── Handler B: Smooth ON, text OFF — ExponentialEaseOut + budget text ──
        local function _PowerSmooth(f)
            local bar = f.targetPowerBar or f.powerBar
            if not bar then return end

            local unit = f.unit
            local pType = _UnitPowerType(unit)
            if pType == nil then return end
            if _G.MSUF_EleMaelstromActive then pType = 0 end
            if f._msufIsPlayer and _G.MSUF_AugEvokerActive then pType = 19 end
            if f._msufIsPlayer and _G.MSUF_ShadowManaActive then pType = 0 end

            local cur = _UnitPower(unit, pType)
            local mx  = _UnitPowerMax(unit, pType)
            if cur == nil then cur = 0 end
            if mx  == nil then mx  = 100 end

            if UFCore_SamePowerSnapshot(f, pType, cur, mx) then return end

            bar:SetMinMaxValues(0, mx, _Interp)
            bar:SetValue(cur, _Interp)

            UFCore_StorePowerSnapshot(f, pType, cur, mx)

            _MaybeUpdatePowerText(f, unit, pType, cur, mx, (f._msufIsPlayer and 0.03) or 0.10)
        end

        -- ── Handler C: Realtime text ON — no interpolation, text every event ──
        local function _PowerRTText(f)
            local bar = f.targetPowerBar or f.powerBar
            if not bar then return end

            local unit = f.unit
            local pType = _UnitPowerType(unit)
            if pType == nil then return end
            if _G.MSUF_EleMaelstromActive then pType = 0 end
            if f._msufIsPlayer and _G.MSUF_AugEvokerActive then pType = 19 end
            if f._msufIsPlayer and _G.MSUF_ShadowManaActive then pType = 0 end

            local cur = _UnitPower(unit, pType)
            local mx  = _UnitPowerMax(unit, pType)
            if cur == nil then cur = 0 end
            if mx  == nil then mx  = 100 end

            if UFCore_SamePowerSnapshot(f, pType, cur, mx) then return end

            bar:SetMinMaxValues(0, mx)
            bar:SetValue(cur)

            UFCore_StorePowerSnapshot(f, pType, cur, mx)

            _MaybeUpdatePowerText(f, unit, pType, cur, mx, nil)
        end

        -- ── Handler D: Both ON — full MidnightRogueBars (hyper-accurate) ──
        local function _PowerFull(f)
            local bar = f.targetPowerBar or f.powerBar
            if not bar then return end

            local unit = f.unit
            local pType = _UnitPowerType(unit)
            if pType == nil then return end
            if _G.MSUF_EleMaelstromActive then pType = 0 end
            if f._msufIsPlayer and _G.MSUF_AugEvokerActive then pType = 19 end
            if f._msufIsPlayer and _G.MSUF_ShadowManaActive then pType = 0 end

            local cur = _UnitPower(unit, pType)
            local mx  = _UnitPowerMax(unit, pType)
            if cur == nil then cur = 0 end
            if mx  == nil then mx  = 100 end

            if UFCore_SamePowerSnapshot(f, pType, cur, mx) then return end

            bar:SetMinMaxValues(0, mx, _Interp)
            bar:SetValue(cur, _Interp)

            UFCore_StorePowerSnapshot(f, pType, cur, mx)

            _MaybeUpdatePowerText(f, unit, pType, cur, mx, nil)
        end

        -- Pre-defined no-op (avoids closure allocation on every swap).
        local _PowerNoop = function() end

        -- ── Pick handler based on settings (called by RefreshSettingsCache) ──
        -- Player frame: selected handler based on toggles.
        -- Non-player frames (target/focus/boss): ALWAYS _PowerOff.
        -- One boolean read per event — negligible vs the 5 C API calls that follow.
        local _playerPowerFn = _PowerOff

        local function _PowerSwapHandler()
            local s = _smoothPowerBar and (_Interp ~= nil)
            local r = _realtimePowerText
            if     s and r     then _playerPowerFn = _PowerFull
            elseif s and not r then _playerPowerFn = _PowerSmooth
            elseif not s and r then _playerPowerFn = _PowerRTText
            else                    _playerPowerFn = _PowerOff
            end
        end

        -- UNIT_POWER_UPDATE: fires for ALL frames (player + target + focus + boss).
        -- Dispatch: player → selected handler, everyone else → _PowerOff.
        DIRECT_APPLY["UNIT_POWER_UPDATE"] = function(f)
            if f._msufIsPlayer then
                return _playerPowerFn(f)
            end
            return _PowerOff(f)
        end

        -- UNIT_POWER_FREQUENT: only registered on player frame (Layer 1 gate).
        -- So this handler ONLY ever fires for player. Direct to selected handler.
        DIRECT_APPLY["UNIT_POWER_FREQUENT"] = function(f)
            return _playerPowerFn(f)
        end

        -- Wire initial handler + expose swap for settings cache.
        _PowerSwapHandler()
        Core._PowerSwapHandler = _PowerSwapHandler

        -- Rare power events → full chain (correct: handles visibility, color, range).
        -- Set visibility-check flag so Elements.Power.Update only does before/after
        -- IsShown tracking on these events (not on UNIT_MAXPOWER which doesn't change visibility).
        local function _PowerVisEvent(f)
            f._msufPowerVisCheckNeeded = true
            powerFn(f)
        end
        DIRECT_APPLY["UNIT_MAXPOWER"]         = powerFn
        DIRECT_APPLY["UNIT_DISPLAYPOWER"]     = _PowerVisEvent
        DIRECT_APPLY["UNIT_POWER_BAR_SHOW"]   = _PowerVisEvent
        DIRECT_APPLY["UNIT_POWER_BAR_HIDE"]   = _PowerVisEvent
    end
end

-- Pre-computed dirty flags for specific events. Eliminates the if/elseif chain
-- that ran on every event (5 string comparisons before reaching DIRECT_APPLY).
-- Lua hash-compares event strings in O(1) via this table lookup.
local EVENT_DIRTY_FLAGS = {
    UNIT_ABSORB_AMOUNT_CHANGED       = "absorbDirty",
    UNIT_HEAL_ABSORB_AMOUNT_CHANGED  = "healAbsorbDirty",
    UNIT_MAXHEALTH                   = "bothAbsorbDirty",
    UNIT_MAXHEALTHMODIFIER           = "bothAbsorbDirty",
    UNIT_FACTION                     = "healthColorDirty",
    UNIT_FLAGS                       = "healthColorDirty",
    UNIT_CLASSIFICATION_CHANGED      = "healthColorDirty",
}

-- PERF P0: Merge DIRECT_APPLY + EVENT_DIRTY_FLAGS into UNIT_EVENT_MAP entries.
-- FrameOnEvent now does ONE hash lookup (UNIT_EVENT_MAP[event]) instead of THREE
-- separate table lookups per event. Saves ~100-200ns × 624 calls/20s.
do
    for ev, dfk in pairs(EVENT_DIRTY_FLAGS) do
        local info = UNIT_EVENT_MAP[ev]
        if info then info.dfk = dfk end
    end
    for ev, fn in pairs(DIRECT_APPLY) do
        local info = UNIT_EVENT_MAP[ev]
        if info then info.direct = fn end
    end
end

-- Byte at position 1 of "UNIT_" is 85 (= 'U'). Use string.byte for the fallback
-- instead of string.sub which allocates a new string on every call.
local BYTE_U = 85  -- string.byte("U")

local function FrameOnEvent(self, event, arg1, ...)
    -- oUF-like: skip hidden frames (free win).
    -- Frames can opt out (e.g. previews) by setting self.MSUF_AllowHiddenEvents = true.
    if not self:IsVisible() and not self.MSUF_AllowHiddenEvents then
        return
    end

    -- Unit events: only react to our unit.
    -- PERF P0: Single lookup carries mask + dirty flags + direct handler (merged).
    local info = UNIT_EVENT_MAP[event]
    if info then
        if arg1 == self.unit then
            -- Set dirty flags via pre-computed map (merged into info, 0 extra lookups).
            local dfk = info.dfk
            if dfk then
                if dfk == "absorbDirty" then
                    self._msufAbsorbDirty = true
                    self._msufAbsorbTextDirty = true
                elseif dfk == "healAbsorbDirty" then
                    self._msufHealAbsorbDirty = true
                elseif dfk == "bothAbsorbDirty" then
                    self._msufAbsorbDirty = true
                    self._msufHealAbsorbDirty = true
                    self._msufAbsorbTextDirty = true
                else -- "healthColorDirty"
                    if not self._msufStaticHealthColor then
                        self._msufHealthColorDirty = true
                    end
                end
            end

            -- Phase 6: Direct-apply for cheap elements (health/power).
            local directFn = info.direct
            if directFn then
                directFn(self)
                return
            end

            Core.MarkDirty(self, info.mask, info.urgent, event)
        end
        return
    end

    -- Fallback: unknown UNIT_* events. Use byte comparison instead of string.sub
    -- to avoid garbage string allocation. Cold path (almost never reached).
    if event:byte(1) == BYTE_U and event:byte(5) == 95 then  -- 95 = '_'
        if arg1 ~= self.unit then return end
        Core.MarkDirty(self, MASK_UNIT_EVENT_FALLBACK, nil, event)
    end
end

function Core.AttachFrame(f)
    if not f or not f.unit then return end

    -- Resolve hot-path fast helpers once (main file loads after UFCore).
    UFCore_ResolveFastFns()

    InitUnitFlags(f)
    FramesByUnit[f.unit] = f

    -- Ensure we start clean.
    f._msufDirtyMask = 0
    f._msufQueuedUFCore = nil
    f._msufWarmupQueuedUFCore = nil
    f._msufVisualQueuedUFCore = nil
    -- PERF: Stagger text rate-limiter seeds so boss1-5 + player + target + focus
    -- don't all hit their 10Hz interval in the same render frame.
    -- After first text update, each frame's next fire is offset by 12.5ms.
    Core._textStaggerIdx = (Core._textStaggerIdx or 0) + 1
    local stagger = (Core._textStaggerIdx % 8) * 0.0125  -- 0, 12.5ms, 25ms, ...
    f._msufTextStagger = stagger
    f._msufHpTxtAt = 0
    f._msufPwrTxtAt = 0
    -- Mark absorb overlays dirty so first health update initializes them.
    f._msufAbsorbDirty = true
    f._msufHealAbsorbDirty = true
    f._msufAbsorbTextDirty = true
    -- Invalidate health diff-gate cache (fresh frame).
    f._msufFlushHP = nil
    f._msufFlushMaxHP = nil

    f:SetScript("OnEvent", FrameOnEvent)

    -- oUF-like: only register what we actually need.
    RefreshUnitEvents(f, true)

    -- Step 3: layout updates only on size/apply changes (never on unit event hotpath).
    if not f._msufUFCoreSizeHooked and f.HookScript then
        f._msufUFCoreSizeHooked = true
        f:HookScript("OnSizeChanged", function(self)
            -- Layout-only flush: clamps + icon anchors, no full redraw.
            Core.RequestLayout(self, "OnSizeChanged")
        end)
    end

    -- If a frame was hidden, it may have missed events due to the visible-gate.
    -- Force a coalesced refresh on show so state is never stale.
    if not f._msufUFCoreShowHooked and f.HookScript then
        f._msufUFCoreShowHooked = true
        f:HookScript("OnShow", function(self)
            -- If hidden, we may have missed absorb/heal-absorb events.
            self._msufAbsorbDirty = true
            self._msufHealAbsorbDirty = true
            self._msufAbsorbTextDirty = true
            self._msufAbsorbInit = nil
            self._msufHealAbsorbInit = nil
            self._msufFlushHP = nil
            self._msufFlushMaxHP = nil
            self._msufPwrTextForce = true
            Core.MarkDirty(self, MASK_SHOW_REFRESH, true, "OnShow")
            DeferSwapWork(self.unit, "OnShow", true)
        end)
    end
    -- Apply initial layout stamps once.
    Core.RequestLayout(f, "AttachFrame")

    -- First draw is queued (coalesced).
    _G.MSUF_QueueUnitframeUpdate(f, true)
end

-- Public wrappers (used by main/options when config toggles change)
function Core.RefreshUnitEvents(f, force)
    RefreshUnitEvents(f, force)
end

-- Centralized event-gating refresh hooks (no behavior change unless called).
-- Use from options/apply flows to recompute element masks when widgets/toggles change.
function Core.RefreshAllUnitEvents(force)
    if force == nil then force = true end
    for _, f in pairs(FramesByUnit) do
        if f then
            RefreshUnitEvents(f, force)
        end
    end
end

-- Notify that configuration for a unit (or all units) changed.
-- By default this only refreshes event-gating; it does NOT force a redraw unless alsoUpdate=true.
function Core.NotifyConfigChanged(unitKey, alsoUpdate, urgent, reason)
    reason = reason or "CONFIG_CHANGED"
    UFCore_RefreshSettingsCache(reason)

    if not unitKey then
        Core.InvalidateAllFrameConfigs()
        Core.RefreshAllUnitEvents(true)
        if alsoUpdate then
            for _, f in pairs(FramesByUnit) do
                if f then
                    Core.MarkDirty(f, DIRTY_FULL, (urgent ~= false), reason)
                end
            end
        end
        return
    end

    local f = FramesByUnit[unitKey]
    if not f then return end

    f.cachedConfig = nil
    -- PERF: Invalidate per-frame combat hot-path caches.
    f._msufCachedShowAbsorbText = nil
    f._msufPwrTextConf = nil
    f._msufHpTextConf = nil
    f._msufPwrPctCleared = nil
    f._msufHpTxtAt = nil
    f._msufStatusConf = nil
    f._msufStatusIconsConf = nil
    f._msufTextSpec = nil
    -- PERF: Invalidate component-level diff caches (Text.lua fast-path guards)
    f._msufLastH = nil
    f._msufLastPctS = nil
    f._msufLastPwrC = nil
    f._msufLastPwrM = nil
    f._msufLastPwrP = nil
    -- PERF: Invalidate raw-value power diff guard (Text.lua P0 guard)
    f._msufRawPwrC = nil
    f._msufRawPwrM = nil
    f._msufRawPwrP = nil
    RefreshUnitEvents(f, true)

    if alsoUpdate then
        Core.MarkDirty(f, DIRTY_FULL, (urgent ~= false), reason)
    end
end

-- ------------------------------------------------------------
-- Global driver (one frame; avoid duplicating global events per unitframe)
-- ------------------------------------------------------------

local Global = CreateFrame("Frame")
Core._globalDriver = Global
_G.MSUF_UFCore_HasToTInlineDriver = true

Global:RegisterEvent("PLAYER_LOGIN")
Global:RegisterEvent("PLAYER_ENTERING_WORLD")
Global:RegisterEvent("ZONE_CHANGED_NEW_AREA")

-- Player-only globals (do not register per unitframe)
Global:RegisterEvent("PLAYER_FLAGS_CHANGED")
Global:RegisterEvent("PLAYER_REGEN_DISABLED")
Global:RegisterEvent("PLAYER_REGEN_ENABLED")
Global:RegisterEvent("PLAYER_UPDATE_RESTING")
Global:RegisterEvent("UPDATE_EXHAUSTION")

-- Phase 1: PLAYER_TARGET_CHANGED / PLAYER_FOCUS_CHANGED moved to EventBus (below)
Global:RegisterEvent("UNIT_THREAT_SITUATION_UPDATE")
Global:RegisterEvent("UNIT_THREAT_LIST_UPDATE")
Global:RegisterEvent("UNIT_TARGET")
Global:RegisterEvent("INSTANCE_ENCOUNTER_ENGAGE_UNIT")
Global:RegisterEvent("GROUP_ROSTER_UPDATE")
Global:RegisterEvent("PARTY_LEADER_CHANGED")
Global:RegisterEvent("RAID_TARGET_UPDATE")
Global:RegisterEvent("UNIT_PET")

local function MarkUnit(unit, mask, urgent, reason)
    local f = FramesByUnit[unit]
    if not f then return end
    Core.MarkDirty(f, mask or DIRTY_FULL, urgent, reason or "GLOBAL")
end

local function QueueUnit(unit, urgent, mask, reason)
    MarkUnit(unit, mask or DIRTY_FULL, urgent, reason or "GLOBAL")
end

-- Coalesced boss engage refresh (INSTANCE_ENCOUNTER_ENGAGE_UNIT can burst on pull).
local _bossEngageQueued = false
local _bossEngageMask = bor(MASK_UNIT_SWAP, DIRTY_VISUAL)
local function _UFCore_FlushBossEngage()
    _bossEngageQueued = false
    for i = 1, 5 do
        local unit = "boss" .. i
        local f = FramesByUnit[unit]
        -- Fast path: only queue live/visible boss frames; skip empty tokens.
        if (UnitExists and UnitExists(unit)) or (f and f.IsShown and f:IsShown()) then
            -- Non-urgent lane: preserve correctness while smoothing pull spikes.
            QueueUnit(unit, false, _bossEngageMask, "INSTANCE_ENCOUNTER_ENGAGE_UNIT")
        end
    end
    -- Boss Target Highlight: re-evaluate after boss frames appear/disappear (pcall-safe)
    local fn = _G.MSUF_UpdateBossTargetHighlight
    if type(fn) == "function" then pcall(fn) end
end
local function _UFCore_ScheduleBossEngage()
    if _bossEngageQueued then return end
    _bossEngageQueued = true
    if After0 then
        After0(0, _UFCore_FlushBossEngage)
    else
        _UFCore_FlushBossEngage()
    end
end

-- Step 4: Explicit Request-Update API boundary (global).
-- Modules should request unitframe updates through this function instead of reaching into internals.
-- This keeps all scheduling/dirty-masking centralized and makes future perf work safer.
--
-- Signature:
--   MSUF_RequestUnitUpdate(unitOrUnits, mask, urgent, reason)
--     unitOrUnits: "player"/"target"/... OR { "player","target",... } OR nil (=> all known frames)
--     mask: dirty mask (defaults DIRTY_FULL)
--     urgent: boolean
--     reason: string
_G.MSUF_RequestUnitUpdate = _G.MSUF_RequestUnitUpdate or function(unitOrUnits, mask, urgent, reason)
    local m = mask or DIRTY_FULL
    local u = (urgent == true) and true or false
    local r = reason or "REQ"

    if unitOrUnits == nil then
        for unit in pairs(FramesByUnit) do
            QueueUnit(unit, u, m, r)
        end
        return
    end

    if type(unitOrUnits) == "table" then
        for i = 1, #unitOrUnits do
            local unit = unitOrUnits[i]
            if type(unit) == "string" and unit ~= "" then
                QueueUnit(unit, u, m, r)
            end
        end
        return
    end

    if type(unitOrUnits) == "string" and unitOrUnits ~= "" then
        QueueUnit(unitOrUnits, u, m, r)
    end
end

local function MarkPlayerStatusIf(flagKey, urgent, reason)
    local pf = FramesByUnit["player"]
    if not pf then return end
    local conf = GetFrameConf(pf)
    if conf and conf[flagKey] then
        Core.MarkDirty(pf, DIRTY_STATUS, urgent, reason)
    end
end

local function DirectIndicatorUnit(unit)
    if not unit then return end
    local f = FramesByUnit[unit]
    if not f or not f:IsVisible() then return end
    local conf = GetFrameConf(f)
    if _IndicatorFast then
        _IndicatorFast(f, conf)
    else
        Core.MarkDirty(f, DIRTY_INDICATOR, false, "DIRECT_INDICATOR_FALLBACK")
    end
end

Global:SetScript("OnEvent", function(_, event, arg1)
    if event == "PLAYER_LOGIN" or event == "PLAYER_ENTERING_WORLD" then
        -- NPC Type instance gate: update on zone change
        local _, instanceType = GetInstanceInfo()
        _npcTypeInstanceActive = (instanceType == "party")
        _G.MSUF_NpcTypeInstanceActive = _npcTypeInstanceActive

        -- Resolve hot-path fast helpers now that the main file has loaded.
        UFCore_ResolveFastFns()

        -- Ensure DB exists before we compute element masks (important for ToT-inline bootstrap).
        UFCore_EnsureDBOnce()

        -- Snapshot general settings + color tables once (fast paths use this cache).
        UFCore_RefreshSettingsCache(event)

        -- Recompute per-frame element masks & unit event registrations once (after DB/init order settles).
        for _, f in pairs(FramesByUnit) do
            RefreshUnitEvents(f, true)

            -- Bootstrap ToT inline on the target frame even when the ToT unitframe itself is disabled.
            if f._msufIsTarget and UFCore_IsToTInlineEnabled() then
                Core.MarkDirty(f, DIRTY_LAYOUT, true, "BOOT_LAYOUT_TOTINLINE")
                Core.MarkDirty(f, DIRTY_TOTINLINE, true, "BOOT_TOTINLINE")
            end

            Core.MarkDirty(f, DIRTY_FULL, true, event)
        end
        return
    end

    if event == "ZONE_CHANGED_NEW_AREA" then
        local _, instanceType = GetInstanceInfo()
        _npcTypeInstanceActive = (instanceType == "party")
        _G.MSUF_NpcTypeInstanceActive = _npcTypeInstanceActive
        -- Refresh cache so npcColorMode toggles between "type" and "reaction"
        UFCore_RefreshSettingsCache("ZONE_NPC_TYPE")
        return
    end

    if event == "PLAYER_REGEN_ENABLED" then
        local set = Core._layoutDeferredSet
        if set then
            for f in pairs(set) do
                set[f] = nil
                local u = f._msufLayoutDeferredUrgent
                f._msufLayoutDeferredUrgent = nil
                -- Apply deferred layout immediately after combat.
                Core.MarkDirty(f, DIRTY_LAYOUT, (u == true) and true or true, "REGEN_LAYOUT")
            end
        end
        MarkPlayerStatusIf("showCombatStateIndicator", true, event)
        return
    end

    if event == "PLAYER_REGEN_DISABLED" then
        MarkPlayerStatusIf("showCombatStateIndicator", true, event)
        return
    end

    if event == "PLAYER_FLAGS_CHANGED" then
        if arg1 == "player" then
            local pf = FramesByUnit["player"]
            if pf and pf:IsVisible() and _StatusFast then
                _RunStatusDirect(pf, DIRTY_STATUS, event)
            else
                MarkUnit("player", DIRTY_STATUS, true, event)
            end
        end
        return
    end

    if event == "PLAYER_UPDATE_RESTING" or event == "UPDATE_EXHAUSTION" then
        MarkPlayerStatusIf("showRestedStateIndicator", false, event)
        return
    end

    -- Phase 1: PLAYER_TARGET_CHANGED handled via EventBus (see bottom of file)

    if event == "UNIT_TARGET" and arg1 == "target" then
        -- Target-of-target changes: refresh ToT inline (independent of the ToT unitframe).
        if UFCore_IsToTInlineEnabled() then
            local tf = FramesByUnit["target"]
            if tf then
                Core.MarkDirty(tf, DIRTY_TOTINLINE, true, event)
            end
        end
        -- If the ToT unitframe exists/attached, keep it responsive too.
        QueueUnit("targettarget", true, MASK_UNIT_SWAP, event)
        DeferSwapWork("targettarget", event, false, false)
        return
    end

    -- Phase 1: PLAYER_FOCUS_CHANGED handled via EventBus (see bottom of file)

    if event == "UNIT_THREAT_SITUATION_UPDATE" or event == "UNIT_THREAT_LIST_UPDATE" then
        -- PERF: Direct-apply threat (like UNIT_HEALTH). Skips MarkDirty + Enqueue + Flush dispatch.
        -- Threat only needs alpha + aggro border (~3μs), queuing adds ~10-15μs overhead per frame.
        if arg1 == "target" or arg1 == "focus"
            or arg1 == "boss1" or arg1 == "boss2" or arg1 == "boss3"
            or arg1 == "boss4" or arg1 == "boss5" then
            local f = FramesByUnit[arg1]
            if f and f:IsVisible() then
                UFCore_UpdateThreatFast(f)
            end
        end
        return
    end

    if event == "INSTANCE_ENCOUNTER_ENGAGE_UNIT" then
        -- PERF: Boss engage can fire in tight pull bursts.
        -- Coalesce to one next-frame pass and queue only live/visible boss units.
        -- This removes redundant urgent-lane spikes while preserving exact frame state.
        _UFCore_ScheduleBossEngage()
        return
    end

    if event == "GROUP_ROSTER_UPDATE" or event == "PARTY_LEADER_CHANGED" then
        -- Leader/assist icon may change on player/target/focus.
        -- Cheap direct lane: avoid waking the UFCore flush driver for icon-only changes.
        DirectIndicatorUnit("player")
        DirectIndicatorUnit("target")
        DirectIndicatorUnit("focus")
        return
    end

    if event == "RAID_TARGET_UPDATE" then
        -- Rare; only update raid marker visuals (no full frame updates required).
        DirectIndicatorUnit("player")
        DirectIndicatorUnit("target")
        DirectIndicatorUnit("focus")
        DirectIndicatorUnit("targettarget")
        return
    end

    if event == "UNIT_PET" then
        local pf = FramesByUnit["pet"]
        if pf then
            pf._msufCachedReactionKind = nil
            pf._msufCachedIsPlayer = nil
            pf._msufHealthColorDirty = true
            Core.MarkDirty(pf, MASK_UNIT_SWAP, true, "UNIT_PET")
        end
        return
    end
end)

-- ---------------------------------------------------------------------------
-- Boss Target Highlight: set _msufBossTargetHLOn flag on boss frames so the
-- Borders.lua priority system can render the highlight overlay.
-- Secret-safe: UnitIsUnit takes string tokens only; guard result anyway.
-- Diff-gated per frame to avoid redundant RefreshRareBarVisuals calls.
-- ---------------------------------------------------------------------------
local _BTH_issecret = _UFCORE_issecret
local _BTH_UnitIsUnit = UnitIsUnit
local _BTH_UnitExists = UnitExists

local function UFCore_UpdateBossTargetHighlight()
    local uf = _G.MSUF_UnitFrames
    if not uf then return end
    local fn = _G.MSUF_RefreshRareBarVisuals

    for i = 1, 5 do
        local bossUnit = "boss" .. i
        local frame = uf[bossUnit]
        if frame then
            local isTarget = false
            if _BTH_UnitExists(bossUnit) then
                local result = _BTH_UnitIsUnit("target", bossUnit)
                if _BTH_issecret and _BTH_issecret(result) then
                    -- secret: keep last known state
                elseif result then
                    isTarget = true
                end
            end

            -- Diff-gate: nil == false for this comparison (avoid spurious RefreshRare on empty boss frames)
            local prev = frame._msufBossTargetHLOn or false
            if prev ~= isTarget then
                frame._msufBossTargetHLOn = isTarget
                -- Trigger border priority re-evaluation (pcall-safe)
                if type(fn) == "function" then pcall(fn, frame) end
            end
        end
    end
end

-- Export for Options/profile refresh
_G.MSUF_UpdateBossTargetHighlight = UFCore_UpdateBossTargetHighlight

-- Phase 1 Fan-out: route PLAYER_TARGET_CHANGED / PLAYER_FOCUS_CHANGED through EventBus
-- so all modules (UFCore, Auras, RangeFade, etc.) share ONE engine-level registration.
do
    local busReg = _G.MSUF_EventBus_Register
    if type(busReg) == "function" then
        busReg("PLAYER_TARGET_CHANGED", "MSUF_UFCORE", function()
            QueueUnit("target", true, MASK_UNIT_SWAP, "PLAYER_TARGET_CHANGED")
            QueueUnit("targettarget", true, MASK_UNIT_SWAP, "PLAYER_TARGET_CHANGED")
            -- Force health color refresh on swap (only when NPC type is active in a 5-man)
            if _npcTypeInstanceActive then
                local tf = FramesByUnit["target"]
                if tf then tf._msufHealthColorDirty = true end
                local ttf = FramesByUnit["targettarget"]
                if ttf then ttf._msufHealthColorDirty = true end
            end
            DeferSwapWork("target", "PLAYER_TARGET_CHANGED", true, false)
            DeferSwapWork("targettarget", "PLAYER_TARGET_CHANGED", false, false)
            -- Boss Target Highlight: update which boss frame shows the target border (pcall-safe)
            local okBTH, errBTH = pcall(UFCore_UpdateBossTargetHighlight)
            if not okBTH and type(errBTH) == "string" then
                -- Debug: print to chat if something goes wrong (should never happen)
                local p = print; if p then p("|cffff4444MSUF BTH error:|r " .. errBTH) end
            end
        end)

        busReg("PLAYER_FOCUS_CHANGED", "MSUF_UFCORE", function()
            QueueUnit("focus", true, MASK_UNIT_SWAP, "PLAYER_FOCUS_CHANGED")
            -- Force health color refresh on swap (only when NPC type is active)
            if _npcTypeInstanceActive then
                local ff = FramesByUnit["focus"]
                if ff then ff._msufHealthColorDirty = true end
            end
            DeferSwapWork("focus", "PLAYER_FOCUS_CHANGED", true, false)
        end)
    end
end

-- Expose a stable attach function name (so main can call it without addon table lookups)
function _G.MSUF_UFCore_AttachFrame(f)
    Core.AttachFrame(f)
end
function _G.MSUF_UFCore_RefreshUnitEvents(f, force)
    RefreshUnitEvents(f, force)
end
function _G.MSUF_UFCore_InvalidateAllFrameConfigs()
    Core.InvalidateAllFrameConfigs()
end

function _G.MSUF_UFCore_RefreshAllUnitEvents(force)
    Core.RefreshAllUnitEvents(force)
end

function _G.MSUF_UFCore_NotifyConfigChanged(unitKey, alsoUpdate, urgent, reason)
    Core.NotifyConfigChanged(unitKey, alsoUpdate, urgent, reason)
end

-- Optional helper for options/profile systems: rebuild settings snapshot cache explicitly.
function _G.MSUF_UFCore_RefreshSettingsCache(reason)
    UFCore_RefreshSettingsCache(reason or "MANUAL")
end

function _G.MSUF_UFCore_GetSettingsCache()
    return UFCore_GetSettingsCache()
end

-- NPC Type instance gate (plain global boolean — zero-cost read from main file)
_G.MSUF_NpcTypeInstanceActive = false

-- Exported for the heavy-visual path in MidnightSimpleUnitFrames.lua
-- so it can refresh the NPC type cache before applying bar colors.
function _G.MSUF_UFCore_RefreshIdentityCache(frame)
    if frame then _RefreshUnitIdentityCache(frame) end
end
