Adv 2.0 Phase L2 step 7: arena tier gate → DnDCharacter.Level

- Rebracket arenaTiers MinLevel to D&D scale (1/4/8/13/18) so arena
  tiers gate on DnDCharacter.Level instead of legacy CombatLevel.
- Auto-advance level gate + reward skill bonus now read Level via a
  new arenaDnDLevelOrZero(userID) helper.
- Delete dead arenaDeathChance (combat engine owns death now) and its
  six tests; drop the math import from the test file.
- Update streak-entry / level-gate tests to use D&D-scale levels.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/plugin/adventure_arena.go

@@ -346,8 +346,11 @@ var arenaStreakEuroMultiplier = [6]float64{0, 1.0, 1.5, 2.0, 2.75, 4.0} // index
 var arenaStreakXPMultiplier = [6]float64{0, 1.0, 1.2, 1.5, 1.85, 2.5}   // index = tiers won
 
 func (p *AdventurePlugin) resolveArenaSurvival(ctx MessageContext, run *ArenaRun, char *AdventureCharacter, tier *ArenaTier, monster *ArenaMonster, result CombatResult, bossNarr *arenaBossNarration) error {
-	// Calculate reward — accumulate in tier earnings, not credited yet
-	reward := arenaRoundReward(tier, run.Round, char.CombatLevel)
+	// Calculate reward — accumulate in tier earnings, not credited yet.
+	// Skill bonus scales off DnDCharacter.Level (post-L2: arena is on the
+	// D&D level scale, not the legacy CombatLevel).
+	skillLevel := arenaDnDLevelOrZero(ctx.Sender)
+	reward := arenaRoundReward(tier, run.Round, skillLevel)
 	run.TierEarnings += reward
 	run.RoundsSurvived++
 	run.LastMonster = monster.Name
@@ -712,37 +715,15 @@ func (p *AdventurePlugin) arenaProcessBail(userID id.UserID, run *ArenaRun) erro
 
 // ── Combat Math ─────────────────────────────────────────────────────────────
 
-func arenaDeathChance(monster *ArenaMonster, char *AdventureCharacter, equip map[EquipmentSlot]*AdvEquipment) float64 {
-	baseDeath := monster.BaseLethality
-	levelMod := float64(monster.ThreatLevel-char.CombatLevel) * 0.015
-	skillMod := math.Max(0, 0.25-float64(char.CombatLevel)*0.008)
-
-	// Average equipment tier → up to 15% reduction at max gear (tier 5 avg = 0.15)
-	var totalTier float64
-	count := 0
-	for _, slot := range allSlots {
-		if eq, ok := equip[slot]; ok {
-			totalTier += float64(eq.Tier)
-			count++
-		}
+// arenaDnDLevelOrZero returns the player's DnDCharacter.Level, or 0 if no
+// sheet exists. Arena enters this path after combat (which migrates), so a
+// zero return is rare and the caller's MinLevel gate handles it correctly.
+func arenaDnDLevelOrZero(userID id.UserID) int {
+	c, err := LoadDnDCharacter(userID)
+	if err != nil || c == nil {
+		return 0
 	}
-	avgTier := 0.0
-	if count > 0 {
-		avgTier = totalTier / float64(count)
-	}
-	equipMod := avgTier * 0.03 // 0 at tier 0, 0.15 at tier 5
-
-	// Housing HP bonus reduces death chance
-	houseMod := char.HouseHPBonus() // 0-20% based on house tier
-
-	// Pet morning defense buff (cat offering / dog smothering)
-	petDefMod := 0.0
-	if char.PetMorningDefense {
-		petDefMod = 0.05
-	}
-
-	deathChance := baseDeath + levelMod - equipMod + skillMod - houseMod - petDefMod
-	return math.Max(0.01, math.Min(0.98, deathChance))
+	return c.Level
 }
 
 func arenaRoundReward(tier *ArenaTier, round int, battleSkill int) int64 {
@@ -860,16 +841,11 @@ func (p *AdventurePlugin) arenaCountdown(userID id.UserID, run *ArenaRun) {
 		return
 	}
 
-	char, err := loadAdvCharacter(userID)
-	if err != nil {
-		slog.Error("arena: failed to load character for auto-advance", "user", userID, "err", err)
-		p.arenaProcessBail(userID, freshRun)
-		return
-	}
-
-	// Level gate for next tier
-	if char.CombatLevel < nextTier.MinLevel {
-		p.SendDM(userID, renderArenaLevelGate(nextTier, char.CombatLevel)+"\n\nYour accumulated rewards have been paid out.")
+	// Level gate for next tier — uses DnDCharacter.Level (post-L2 arena
+	// is on the D&D level scale).
+	playerLevel := arenaDnDLevelOrZero(userID)
+	if playerLevel < nextTier.MinLevel {
+		p.SendDM(userID, renderArenaLevelGate(nextTier, playerLevel)+"\n\nYour accumulated rewards have been paid out.")
 		p.arenaProcessBail(userID, freshRun)
 		return
 	}

internal/plugin/adventure_arena_monsters.go

@@ -29,7 +29,7 @@ type ArenaMonster struct {
 var arenaTiers = [5]ArenaTier{
 	// Tier 1 — Scrubs
 	{
-		Number: 1, Name: "Scrubs", MinLevel: 1,
+		Number: 1, Name: "Scrubs", MinLevel: 1, // DnD Level 1–3
 		BasePayout: 150, SkillMultiplier: 1.0, CompletionBonus: 2500, BattleXP: 10,
 		Monsters: [4]ArenaMonster{
 			{
@@ -56,7 +56,7 @@ var arenaTiers = [5]ArenaTier{
 	},
 	// Tier 2 — Thugs
 	{
-		Number: 2, Name: "Thugs", MinLevel: 10,
+		Number: 2, Name: "Thugs", MinLevel: 4, // DnD Level 4–7
 		BasePayout: 500, SkillMultiplier: 2.5, CompletionBonus: 10000, BattleXP: 25,
 		Monsters: [4]ArenaMonster{
 			{
@@ -84,7 +84,7 @@ var arenaTiers = [5]ArenaTier{
 	},
 	// Tier 3 — Brutes
 	{
-		Number: 3, Name: "Brutes", MinLevel: 25,
+		Number: 3, Name: "Brutes", MinLevel: 8, // DnD Level 8–12
 		BasePayout: 1500, SkillMultiplier: 6.0, CompletionBonus: 30000, BattleXP: 60,
 		Monsters: [4]ArenaMonster{
 			{
@@ -113,7 +113,7 @@ var arenaTiers = [5]ArenaTier{
 	},
 	// Tier 4 — Horrors
 	{
-		Number: 4, Name: "Horrors", MinLevel: 45,
+		Number: 4, Name: "Horrors", MinLevel: 13, // DnD Level 13–17
 		BasePayout: 5000, SkillMultiplier: 12.0, CompletionBonus: 100000, BattleXP: 120,
 		Monsters: [4]ArenaMonster{
 			{
@@ -143,7 +143,7 @@ var arenaTiers = [5]ArenaTier{
 	},
 	// Tier 5 — World Eaters
 	{
-		Number: 5, Name: "World Eaters", MinLevel: 70,
+		Number: 5, Name: "World Eaters", MinLevel: 18, // DnD Level 18–20
 		BasePayout: 15000, SkillMultiplier: 25.0, CompletionBonus: 500000, BattleXP: 250,
 		Monsters: [4]ArenaMonster{
 			{

internal/plugin/adventure_arena_test.go

@@ -1,7 +1,6 @@
 package plugin
 
 import (
-	"math"
 	"strings"
 	"testing"
 	"time"
@@ -107,96 +106,6 @@ func TestArenaMinLevel_Increasing(t *testing.T) {
 	}
 }
 
-// ── Death Chance Formula Tests ──────────────────────────────────────────────
-
-func TestArenaDeathChance_Clamped(t *testing.T) {
-	// Min-level player with tier 0 gear vs easiest monster
-	char := &AdventureCharacter{CombatLevel: 1}
-	equip := map[EquipmentSlot]*AdvEquipment{
-		SlotWeapon: {Tier: 0}, SlotArmor: {Tier: 0}, SlotHelmet: {Tier: 0},
-		SlotBoots: {Tier: 0}, SlotTool: {Tier: 0},
-	}
-	monster := arenaGetMonster(1, 1)
-	dc := arenaDeathChance(monster, char, equip)
-	if dc < 0.01 || dc > 0.98 {
-		t.Errorf("death chance %f out of [0.01, 0.98] bounds", dc)
-	}
-}
-
-func TestArenaDeathChance_MaxGearReduces(t *testing.T) {
-	// Use a mid-tier monster where gear difference is visible above the floor
-	char := &AdventureCharacter{CombatLevel: 25}
-	monster := arenaGetMonster(3, 3) // Behemoth Adjacent (0.73 lethality)
-
-	noGear := map[EquipmentSlot]*AdvEquipment{
-		SlotWeapon: {Tier: 0}, SlotArmor: {Tier: 0}, SlotHelmet: {Tier: 0},
-		SlotBoots: {Tier: 0}, SlotTool: {Tier: 0},
-	}
-	maxGear := map[EquipmentSlot]*AdvEquipment{
-		SlotWeapon: {Tier: 5}, SlotArmor: {Tier: 5}, SlotHelmet: {Tier: 5},
-		SlotBoots: {Tier: 5}, SlotTool: {Tier: 5},
-	}
-
-	dcNoGear := arenaDeathChance(monster, char, noGear)
-	dcMaxGear := arenaDeathChance(monster, char, maxGear)
-
-	if dcMaxGear >= dcNoGear {
-		t.Errorf("max gear (%f) should reduce death chance vs no gear (%f)", dcMaxGear, dcNoGear)
-	}
-}
-
-func TestArenaDeathChance_HighLevelReduces(t *testing.T) {
-	equip := map[EquipmentSlot]*AdvEquipment{
-		SlotWeapon: {Tier: 3}, SlotArmor: {Tier: 3}, SlotHelmet: {Tier: 3},
-		SlotBoots: {Tier: 3}, SlotTool: {Tier: 3},
-	}
-	monster := arenaGetMonster(3, 4) // The Inevitable
-
-	lowLevel := &AdventureCharacter{CombatLevel: 25}
-	highLevel := &AdventureCharacter{CombatLevel: 50}
-
-	dcLow := arenaDeathChance(monster, lowLevel, equip)
-	dcHigh := arenaDeathChance(monster, highLevel, equip)
-
-	if dcHigh >= dcLow {
-		t.Errorf("high level (%f) should have lower death chance than low level (%f)", dcHigh, dcLow)
-	}
-}
-
-func TestArenaDeathChance_T5R4_AlwaysTerrifying(t *testing.T) {
-	// Even max-everything player faces high death at T5R4
-	char := &AdventureCharacter{CombatLevel: 50}
-	equip := map[EquipmentSlot]*AdvEquipment{
-		SlotWeapon: {Tier: 5}, SlotArmor: {Tier: 5}, SlotHelmet: {Tier: 5},
-		SlotBoots: {Tier: 5}, SlotTool: {Tier: 5},
-	}
-	monster := arenaGetMonster(5, 4) // That Which Has Always Been
-
-	dc := arenaDeathChance(monster, char, equip)
-	if dc < 0.30 {
-		t.Errorf("T5R4 death chance for max player (%f) should be >= 0.30", dc)
-	}
-	// Should hit the 0.98 ceiling
-	if dc > 0.98 {
-		t.Errorf("T5R4 death chance (%f) exceeds ceiling 0.98", dc)
-	}
-}
-
-func TestArenaDeathChance_Floor(t *testing.T) {
-	// Even with absurd stats, floor is 0.01
-	char := &AdventureCharacter{CombatLevel: 50}
-	equip := map[EquipmentSlot]*AdvEquipment{
-		SlotWeapon: {Tier: 5}, SlotArmor: {Tier: 5}, SlotHelmet: {Tier: 5},
-		SlotBoots: {Tier: 5}, SlotTool: {Tier: 5},
-	}
-	monster := &ArenaMonster{BaseLethality: 0.01, ThreatLevel: 1}
-
-	dc := arenaDeathChance(monster, char, equip)
-	if dc < 0.01 {
-		t.Errorf("death chance %f below floor 0.01", dc)
-	}
-}
-
 // ── Reward Formula Tests ────────────────────────────────────────────────────
 
 func TestArenaRoundReward(t *testing.T) {
@@ -243,38 +152,11 @@ func TestArenaRewardScaling(t *testing.T) {
 	}
 }
 
-// ── Death Chance Formula Component Tests ────────────────────────────────────
-
-func TestArenaDeathChance_Components(t *testing.T) {
-	// Verify formula components individually
-	// death_chance = base + level_mod - equip_mod + skill_mod
-
-	// Level 1, tier 0 gear, T1R1 monster (lethality=0.10, threat=2)
-	char := &AdventureCharacter{CombatLevel: 1}
-	equip := map[EquipmentSlot]*AdvEquipment{
-		SlotWeapon: {Tier: 0}, SlotArmor: {Tier: 0}, SlotHelmet: {Tier: 0},
-		SlotBoots: {Tier: 0}, SlotTool: {Tier: 0},
-	}
-	monster := &ArenaMonster{BaseLethality: 0.10, ThreatLevel: 2}
-
-	dc := arenaDeathChance(monster, char, equip)
-
-	// Manual calculation:
-	// base = 0.10
-	// level_mod = (2-1) * 0.015 = 0.015
-	// skill_mod = max(0, 0.25 - 1*0.008) = 0.242
-	// equip_mod = 0 * 0.03 = 0 (tier 0 gives no equipment bonus)
-	// death_chance = 0.10 + 0.015 - 0 + 0.242 = 0.357
-	expected := 0.10 + 0.015 + 0.242
-	if math.Abs(dc-expected) > 0.001 {
-		t.Errorf("T1R1 components: got %f, expected ~%f", dc, expected)
-	}
-}
-
 // ── Render Tests ────────────────────────────────────────────────────────────
 
 func TestRenderArenaStreakEntry(t *testing.T) {
-	char := &DnDCharacter{Level: 30}
+	// Level 5 unlocks T1+T2 only (post-L2 brackets: 1/4/8/13/18); T3-T5 locked.
+	char := &DnDCharacter{Level: 5}
 	tier := arenaGetTier(1)
 	monster := arenaGetMonster(1, 1)
 
@@ -603,8 +485,8 @@ func TestRenderArenaStreakEntry_ShowsMultipliers(t *testing.T) {
 }
 
 func TestRenderArenaStreakEntry_HighLevel_AllEligible(t *testing.T) {
-	// T5 requires level 70, so use level 70+ to unlock everything
-	char := &DnDCharacter{Level: 70}
+	// T5 requires level 18 (post-L2 D&D scale); level 20 unlocks everything.
+	char := &DnDCharacter{Level: 20}
 	tier := arenaGetTier(1)
 	monster := arenaGetMonster(1, 1)
 
@@ -780,11 +662,11 @@ func TestRenderArenaLeaderboard_WithEntries(t *testing.T) {
 
 func TestRenderArenaLevelGate(t *testing.T) {
 	tier := arenaGetTier(3)
-	text := renderArenaLevelGate(tier, 10)
-	if !strings.Contains(text, "Level 25") {
+	text := renderArenaLevelGate(tier, 5)
+	if !strings.Contains(text, "Level 8") {
 		t.Error("gate message should show required level")
 	}
-	if !strings.Contains(text, "Level 10") {
+	if !strings.Contains(text, "Level 5") {
 		t.Error("gate message should show player level")
 	}
 }