D&D: weighted race-balance pass — tune races to equal effective power

Flat net ability mods aren't equal *effective* power: a +1 in a stat a
build uses beats a +1 in a dump stat. Add dnd_race_balance.go, which
scores each race's mods against a 60/40 blend of per-class combat stat
priorities and class-independent non-combat utility (zone locks,
expedition harvest, skill checks, haggling).

Retune all races so their mean score across playable classes lands
within ±0.5 of the Standard Human baseline (6.0); best-fit/worst-fit
spread is kept as intentional race identity. TestRaceBalance logs the
report and asserts the rule.

internal/plugin/dnd.go

@@ -71,13 +71,21 @@ type DnDClassInfo struct {
 	Playable bool
 }
 
+// Race mods are tuned for equal *effective* power, not equal net total.
+// The weighted balance pass (dnd_race_balance.go) scores each race's mods
+// against a blend of per-class combat priorities and class-independent
+// non-combat utility (zone locks, harvest, skills, haggling). These blocks
+// are tuned so every race's mean score across all playable classes lands
+// near the Standard Human baseline of 6.0. Net mod totals vary (Elf +7,
+// Orc +6) — a spiky race concentrated into high-value stats needs fewer
+// points to match a flat one.
 var dndRaces = []DnDRaceInfo{
 	{RaceHuman, "Human", [6]int{1, 1, 1, 1, 1, 1}, "Versatile: +1 to every ability score"},
-	{RaceElf, "Elf", [6]int{0, 3, -1, 2, 2, 0}, "Darkvision; immune to sleep effects"},
-	{RaceDwarf, "Dwarf", [6]int{2, -1, 3, 1, 2, -1}, "Poison resistance; bonus vs. underground enemies"},
+	{RaceElf, "Elf", [6]int{0, 3, -1, 2, 3, 0}, "Darkvision; immune to sleep effects"},
+	{RaceDwarf, "Dwarf", [6]int{2, -1, 3, 1, 1, -1}, "Poison resistance; bonus vs. underground enemies"},
 	{RaceHalfling, "Halfling", [6]int{0, 3, 1, 0, 2, 0}, "Lucky: once per combat, reroll a natural 1"},
-	{RaceOrc, "Orc", [6]int{5, -1, 4, -1, -1, 0}, "Rage: once per combat, +50% damage for one turn"},
-	{RaceTiefling, "Tiefling", [6]int{0, 2, 0, 2, 0, 2}, "Fire resistance; bonus on CHA checks"},
+	{RaceOrc, "Orc", [6]int{6, -1, 3, -1, -1, 0}, "Rage: once per combat, +50% damage for one turn"},
+	{RaceTiefling, "Tiefling", [6]int{0, 2, 0, 1, 0, 3}, "Fire resistance; bonus on CHA checks"},
 	{RaceHalfElf, "Half-Elf", [6]int{0, 2, 0, 1, 1, 2}, "Two bonus skill proficiencies"},
 }
 

internal/plugin/dnd_race_balance.go

@@ -0,0 +1,197 @@
+package plugin
+
+import (
+	"math"
+	"sort"
+)
+
+// Weighted race-balance model. Drives the race-mod tuning in dnd.go
+// (see gogobee_dnd_design_doc and the project memory).
+//
+// Flat net ability mods are NOT equal *effective* power: a +1 in a stat a
+// build actually uses is worth far more than a +1 in a dump stat. This
+// model scores each race by weighting its mods against a blend of (a) the
+// combat stat priorities of each class and (b) a class-independent
+// "utility" weight for how much each stat does *outside* combat — zone
+// locks, expedition harvest, skill checks, haggling. See classStatWeights
+// and the combatUtilityBlend constant.
+//
+// Every weight block is normalized to sum to 6.0 — so a perfectly flat race
+// (+1 to every stat) scores exactly its net mod total (6.0) under ANY
+// class. A spiky race scores above baseline with a class that wants its
+// high stats, below with one that doesn't. The best-fit score is therefore
+// the race's realistic effective-power ceiling.
+
+// ability score indices into the [6]int Mods block.
+const (
+	statSTR = 0
+	statDEX = 1
+	statCON = 2
+	statINT = 3
+	statWIS = 4
+	statCHA = 5
+)
+
+func statIndex(name string) int {
+	switch name {
+	case "STR":
+		return statSTR
+	case "DEX":
+		return statDEX
+	case "CON":
+		return statCON
+	case "INT":
+		return statINT
+	case "WIS":
+		return statWIS
+	case "CHA":
+		return statCHA
+	}
+	return -1
+}
+
+// normalizeWeights scales a raw weight block so it sums to 6.0 — the point
+// where a flat +1-to-all race scores its net mod total (6.0) under it.
+func normalizeWeights(w [6]float64) [6]float64 {
+	var sum float64
+	for _, v := range w {
+		sum += v
+	}
+	if sum == 0 {
+		return w
+	}
+	for i := range w {
+		w[i] = w[i] * 6 / sum
+	}
+	return w
+}
+
+// combatStatWeights returns the per-class *combat* weight block. Raw role
+// weights, before normalization:
+//
+//	primary attack stat (PrimaryA) ... 4
+//	secondary stat (PrimaryB) ........ 2
+//	CON (survivability) .............. 3
+//	everything else (saves/skills) ... 1
+//
+// CON is weighted highly for every class — HP keeps you in the fight
+// regardless of build. Where a class's PrimaryA/PrimaryB *is* CON, the
+// higher weight wins (max, not sum).
+func combatStatWeights(c DnDClassInfo) [6]float64 {
+	var w [6]float64
+	for i := range w {
+		w[i] = 1 // floor: saves, skills, utility
+	}
+	if w[statCON] < 3 {
+		w[statCON] = 3 // survivability matters for every class
+	}
+	if i := statIndex(c.PrimaryB); i >= 0 && w[i] < 2 {
+		w[i] = 2
+	}
+	if i := statIndex(c.PrimaryA); i >= 0 && w[i] < 4 {
+		w[i] = 4
+	}
+	return normalizeWeights(w)
+}
+
+// utilityStatWeights is the class-independent *non-combat* weight block:
+// how much each stat does outside a fight. Derived from a codebase audit
+// of where ability mods drive non-combat outcomes — zone-navigation stat
+// locks (zone_graph_nav.go), expedition harvest yields (dnd_expedition_
+// harvest.go), night/transit checks, the 11-skill system with its NPC
+// cost-refund hooks (dnd_skills.go), and CHA hospital-bill haggling
+// (adventure_hospital.go). Raw weights, before normalization:
+//
+//	STR ... 2.0  (one zone lock, mining harvest)
+//	DEX ... 3.0  (two zone locks, fishing harvest, AC)
+//	CON ... 5.0  (two locks, short-rest healing, level-up HP, night checks)
+//	INT ... 3.5  (one lock, Arcana/Investigation, scavenge + essence harvest)
+//	WIS ... 5.0  (one lock, Perception/Insight, healing, forage + commune, night)
+//	CHA ... 4.0  (three locks, Persuasion/Intimidation/Deception, haggling)
+func utilityStatWeights() [6]float64 {
+	return normalizeWeights([6]float64{2.0, 3.0, 5.0, 3.5, 5.0, 4.0})
+}
+
+// combatUtilityBlend is how much a character's effective power comes from
+// combat vs. everything else (zones, expeditions, harvest, skills,
+// haggling). gogobee is combat-forward but not combat-only.
+const combatUtilityBlend = 0.6
+
+// classStatWeights is the blended per-class weight block used for scoring:
+// combatUtilityBlend of the class's combat weights plus the remainder of
+// the class-independent utility weights. Both components are normalized to
+// sum 6.0, so the blend is too — a flat +1-to-all race still scores exactly
+// 6.0 under every class.
+func classStatWeights(c DnDClassInfo) [6]float64 {
+	combat := combatStatWeights(c)
+	utility := utilityStatWeights()
+	var w [6]float64
+	for i := range w {
+		w[i] = combatUtilityBlend*combat[i] + (1-combatUtilityBlend)*utility[i]
+	}
+	return w
+}
+
+// raceScore is the weighted effective-power of a race under one class:
+// Σ mod[i] * weight[i].
+func raceScore(mods [6]int, w [6]float64) float64 {
+	var s float64
+	for i := 0; i < 6; i++ {
+		s += float64(mods[i]) * w[i]
+	}
+	return s
+}
+
+// raceBalanceBaseline is the Standard Human score under every class:
+// +1 to all six stats × weights summing to 6.0.
+const raceBalanceBaseline = 6.0
+
+// raceBalance is one race's result in the weighted balance pass.
+type raceBalance struct {
+	Race       DnDRace
+	BestClass  DnDClass
+	BestScore  float64 // effective-power ceiling (best-fit class)
+	WorstClass DnDClass
+	WorstScore float64 // effective-power floor (worst-fit class)
+	AvgScore   float64 // mean across all playable classes
+}
+
+// Delta is the race's best-fit score minus the Standard Human baseline.
+// Positive = over-performs a flat +1-to-all race at its optimal build.
+func (rb raceBalance) Delta() float64 { return rb.BestScore - raceBalanceBaseline }
+
+// computeRaceBalance scores every race's mods against every playable class
+// and reports its best-fit, worst-fit, and average effective power.
+// Results are sorted by Delta descending — biggest over-performers first.
+func computeRaceBalance() []raceBalance {
+	out := make([]raceBalance, 0, len(dndRaces))
+	for _, ri := range dndRaces {
+		rb := raceBalance{Race: ri.Key, WorstScore: math.Inf(1)}
+		var total float64
+		var n int
+		first := true
+		for _, ci := range dndClasses {
+			if !ci.Playable {
+				continue
+			}
+			s := raceScore(ri.Mods, classStatWeights(ci))
+			if first || s > rb.BestScore {
+				rb.BestScore, rb.BestClass = s, ci.Key
+			}
+			if s < rb.WorstScore {
+				rb.WorstScore, rb.WorstClass = s, ci.Key
+			}
+			total += s
+			n++
+			first = false
+		}
+		if n > 0 {
+			rb.AvgScore = total / float64(n)
+		}
+		out = append(out, rb)
+	}
+	sort.SliceStable(out, func(i, j int) bool {
+		return out[i].Delta() > out[j].Delta()
+	})
+	return out
+}

internal/plugin/dnd_test.go

@@ -106,21 +106,49 @@ func TestComputeAC(t *testing.T) {
 }
 
 func TestApplyRaceMods(t *testing.T) {
-	// Elf: STR +0, DEX +3, CON -1, INT +2, WIS +2, CHA +0
+	// Elf: STR +0, DEX +3, CON -1, INT +2, WIS +3, CHA +0
 	base := [6]int{10, 10, 10, 10, 10, 10}
 	got := applyRaceMods(RaceElf, base)
-	want := [6]int{10, 13, 9, 12, 12, 10}
+	want := [6]int{10, 13, 9, 12, 13, 10}
 	if got != want {
 		t.Errorf("applyRaceMods(Elf) = %v, want %v", got, want)
 	}
-	// Orc: STR +5, DEX -1, CON +4, INT -1, WIS -1, CHA +0
+	// Orc: STR +6, DEX -1, CON +3, INT -1, WIS -1, CHA +0
 	got = applyRaceMods(RaceOrc, base)
-	want = [6]int{15, 9, 14, 9, 9, 10}
+	want = [6]int{16, 9, 13, 9, 9, 10}
 	if got != want {
 		t.Errorf("applyRaceMods(Orc) = %v, want %v", got, want)
 	}
 }
 
+// TestRaceBalance runs the weighted balance pass and logs the report.
+// Standard Human baseline is 6.0 under every class; a race's best-fit
+// score is its realistic effective-power ceiling. The assertion is a
+// generous guard rail — see classStatWeights for the model.
+func TestRaceBalance(t *testing.T) {
+	report := computeRaceBalance()
+	t.Logf("weighted race-balance pass (Human baseline = %.1f)", raceBalanceBaseline)
+	t.Logf("%-10s %-9s %6s  %-9s %6s  %6s  %+6s",
+		"race", "best-fit", "score", "worst-fit", "score", "avg", "Δ")
+	for _, rb := range report {
+		t.Logf("%-10s %-9s %6.2f  %-9s %6.2f  %6.2f  %+6.2f",
+			rb.Race, rb.BestClass, rb.BestScore,
+			rb.WorstClass, rb.WorstScore, rb.AvgScore, rb.Delta())
+	}
+	// Balance rule: equal *average* power. Every race's mean score across
+	// all playable classes must land within tolerance of the Human
+	// baseline. Best-fit/worst-fit spread is intentional race identity —
+	// a spiky race trades a higher ceiling for a lower floor — so only
+	// the average is asserted.
+	const tolerance = 0.5
+	for _, rb := range report {
+		if d := rb.AvgScore - raceBalanceBaseline; d < -tolerance || d > tolerance {
+			t.Errorf("%s avg %.2f is %.2f off the %.1f baseline (tolerance %.1f)",
+				rb.Race, rb.AvgScore, d, raceBalanceBaseline, tolerance)
+		}
+	}
+}
+
 func TestParseRaceClass(t *testing.T) {
 	if r, ok := parseRace("Elf"); !ok || r != RaceElf {
 		t.Errorf("parseRace(Elf) = %v, %v", r, ok)