feat(inventory-go): Mag-Tools OD weapon rating calculation (od.go)

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

go-services/inventory-go/od_test.go

@@ -0,0 +1,97 @@
+package main
+
+import (
+	"math"
+	"testing"
+)
+
+func approx(a, b float64) bool { return math.Abs(a-b) < 0.01 }
+
+// Wand: OD = (buffedElemVsMonsters - tableMaxElemVsMonsters) * 100.
+// Live "Frost Baton": skill 34 (war), wieldreq 385, ElemVsMonsters 1.40,
+// no spirit-drinker spells. Table max for (34,*,*,385) = 1.18 → OD = +22.
+func TestOD_Wand(t *testing.T) {
+	raw := map[string]any{
+		"ObjectClass": 31.0,
+		"IntValues":   map[string]any{"159": 34.0, "160": 385.0},
+		"DoubleValues": map[string]any{"152": 1.40, "167772169": 8.0},
+		"Spells": []any{}, "ActiveSpells": []any{},
+	}
+	od, ok := computeOD(raw)
+	if !ok || !approx(od, 22.0) {
+		t.Fatalf("wand OD = %v ok=%v, want +22", od, ok)
+	}
+}
+
+// Non-loot (no workmanship) → no OD.
+func TestOD_NonLootNull(t *testing.T) {
+	raw := map[string]any{
+		"ObjectClass":  31.0,
+		"IntValues":    map[string]any{"159": 34.0, "160": 385.0},
+		"DoubleValues": map[string]any{"152": 1.40},
+		"Spells":       []any{}, "ActiveSpells": []any{},
+	}
+	if _, ok := computeOD(raw); ok {
+		t.Fatal("no-workmanship item must have no OD")
+	}
+}
+
+// Table lookup miss (unknown tier) → no OD.
+func TestOD_UnknownTierNull(t *testing.T) {
+	raw := map[string]any{
+		"ObjectClass":  31.0,
+		"IntValues":    map[string]any{"159": 34.0, "160": 999.0},
+		"DoubleValues": map[string]any{"152": 1.40, "167772169": 8.0},
+		"Spells":       []any{}, "ActiveSpells": []any{},
+	}
+	if _, ok := computeOD(raw); ok {
+		t.Fatal("unknown wieldreq tier must have no OD")
+	}
+}
+
+// Melee: OD = buffedMaxDmg - varianceTinks - tableMaxDmg,
+// varianceTinks = round(log(tableMaxVar/variance)/log(0.8), 2).
+// Heavy (44) sword (2) non-MS, wieldreq 430: tableMaxDmg=71, tableMaxVar=0.47.
+// A perfect retail-max item: maxDmg 71, variance 0.47 → varianceTinks=0 → OD 0.
+func TestOD_MeleeRetailMaxIsZero(t *testing.T) {
+	raw := map[string]any{
+		"ObjectClass":  1.0,
+		"IntValues":    map[string]any{"159": 44.0, "353": 2.0, "160": 430.0, "218103842": 71.0},
+		"DoubleValues": map[string]any{"167772171": 0.47, "167772169": 10.0},
+		"Spells":       []any{}, "ActiveSpells": []any{},
+	}
+	od, ok := computeOD(raw)
+	if !ok || !approx(od, 0.0) {
+		t.Fatalf("melee retail-max OD = %v ok=%v, want 0", od, ok)
+	}
+}
+
+// Melee with tighter variance (0.376 = one granite tink below 0.47):
+// varianceTinks = round(log(0.47/0.376)/log(0.8), 2) = round(1.00,2)=1 → OD = 71-1-71 = -1.
+func TestOD_MeleeOneTinkVariance(t *testing.T) {
+	raw := map[string]any{
+		"ObjectClass":  1.0,
+		"IntValues":    map[string]any{"159": 44.0, "353": 2.0, "160": 430.0, "218103842": 71.0},
+		"DoubleValues": map[string]any{"167772171": 0.376, "167772169": 10.0},
+		"Spells":       []any{}, "ActiveSpells": []any{},
+	}
+	od, ok := computeOD(raw)
+	if !ok || !approx(od, -1.0) {
+		t.Fatalf("melee OD = %v ok=%v, want -1", od, ok)
+	}
+}
+
+// Melee buffed: innate Legendary Blood Thirst (id 6089, +10 MaxDamage).
+// maxDmg 61 + 10 = 71, variance 0.47 → OD 0 (vs 71 table).
+func TestOD_MeleeBuffedByBloodThirst(t *testing.T) {
+	raw := map[string]any{
+		"ObjectClass":  1.0,
+		"IntValues":    map[string]any{"159": 44.0, "353": 2.0, "160": 430.0, "218103842": 61.0},
+		"DoubleValues": map[string]any{"167772171": 0.47, "167772169": 10.0},
+		"Spells":       []any{6089.0}, "ActiveSpells": []any{},
+	}
+	od, ok := computeOD(raw)
+	if !ok || !approx(od, 0.0) {
+		t.Fatalf("melee buffed OD = %v ok=%v, want 0", od, ok)
+	}
+}