J3 D8-d-fix: caster AC floor + HP ×1.25

computeAC: lift caster floors (cleric/druid 3→5, bard/warlock 1→3,
mage/sorcerer 0→2). Ranger 3 / rogue 1 / fighter+paladin 6 unchanged.

computeMaxHP: new casterHPMult(class) = 1.25 for the same caster set,
applied multiplicatively on top of phase5BHPMult. Martials unchanged.
New caster L10 HPMax: mage/sorc ~98 (was 78), bard/cleric/druid/warlock
~118 (was 95); martial L10 ~141 unchanged.

bootstrap_caster_hp.go: new bootstrapCasterHPRefresh (job key
caster_hp_refresh_v1) refreshes existing rows once at startup; mirrors
bootstrapPhase5BHPRefresh — only raises HPMax, preserves absolute
wound. Wired in adventure.go.

Measured on n=2500 d8dfix2 corpus (gitignored sim_results) vs d8c:
- T3 manor caster lift confirmed — bard +13 (43→56), druid +8 (88→96),
  warlock +8, sorcerer +5, mage +5, cleric +2. Martials flat.
- Macro deltas: bard +2.6, warlock +2.0, druid +1.4, mage/sorcerer +1.0,
  cleric -0.2. n=500 1σ ≈ 2.2pp — bard/warlock cleanly past noise.
- T4 underdark wall still holds (every caster ~0%). Lift directionally
  correct but undersized for T4 atk-bonus + multiattack — separate
  follow-up.
- T5 dragons_lair universal wall unchanged (martials TPK too).

Diagnostic context: project_d8d_diagnostic. Cleric flat manor likely
the concentration AOE re-tick engine gap (filed for D8-e+).

internal/plugin/dnd.go

@@ -161,6 +161,20 @@ func abilityModifier(score int) int {
 // startup to refresh stale rows.
 const phase5BHPMult = 1.5
 
+// casterHPMult is the J3 D8-d-fix caster durability lift. T4 sim showed
+// caster HPMax sat ~30% below martial (~95 vs 141 at L10) and the AC-floor
+// lift alone wasn't enough to crack the wall. Applied multiplicatively in
+// computeMaxHP on top of phase5BHPMult so the existing Phase 5-B floor
+// stays intact for martials. Refreshed for existing rows by
+// bootstrapCasterHPRefresh (job key caster_hp_refresh_v1).
+func casterHPMult(class DnDClass) float64 {
+	switch class {
+	case ClassCleric, ClassDruid, ClassBard, ClassWarlock, ClassMage, ClassSorcerer:
+		return 1.25
+	}
+	return 1.0
+}
+
 // computeMaxHP — D&D5e style. L1: full HP die + CON mod (min 1).
 // Per level after: average HP die (roundup of die/2 + 1) + CON mod.
 // The result is scaled by phase5BHPMult — see that constant for the
@@ -181,8 +195,8 @@ func computeMaxHP(class DnDClass, conMod, level int) int {
 		}
 		hp += gain
 	}
-	// Phase 5-B player power floor — round to nearest int.
-	scaled := int(float64(hp)*phase5BHPMult + 0.5)
+	// Phase 5-B player power floor + J3 D8-d-fix caster lift — round to nearest int.
+	scaled := int(float64(hp)*phase5BHPMult*casterHPMult(class) + 0.5)
 	if scaled < 1 {
 		scaled = 1
 	}
@@ -197,10 +211,16 @@ func computeAC(class DnDClass, dexMod int) int {
 	switch class {
 	case ClassFighter, ClassPaladin:
 		floor = 6 // heavy/medium-armor baseline
-	case ClassCleric, ClassRanger, ClassDruid:
+	case ClassCleric, ClassDruid:
+		floor = 5
+	case ClassRanger:
 		floor = 3
-	case ClassRogue, ClassBard, ClassWarlock:
+	case ClassBard, ClassWarlock:
+		floor = 3
+	case ClassRogue:
 		floor = 1
+	case ClassMage, ClassSorcerer:
+		floor = 2
 	}
 	return 10 + dexMod + floor
 }