Initial commit: Luminary AI Gateway

OpenAI-compatible AI gateway with Vue admin UI, multi-provider egress,
ingress key governance, monitoring, and security controls.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/balancer/weighted.go

@@ -0,0 +1,49 @@
+package balancer
+
+import (
+	"math/rand"
+
+	"github.com/rose_cat707/luminary/internal/model"
+)
+
+type KeyCandidate struct {
+	Key    model.ProviderKey
+	Weight float64
+}
+
+func SelectWeighted(candidates []KeyCandidate) *model.ProviderKey {
+	if len(candidates) == 0 {
+		return nil
+	}
+	if len(candidates) == 1 {
+		k := candidates[0].Key
+		return &k
+	}
+	var total float64
+	for _, c := range candidates {
+		w := c.Weight
+		if w <= 0 {
+			w = 1
+		}
+		total += w
+	}
+	if total <= 0 {
+		k := candidates[0].Key
+		return &k
+	}
+	r := rand.Float64() * total
+	var acc float64
+	for _, c := range candidates {
+		w := c.Weight
+		if w <= 0 {
+			w = 1
+		}
+		acc += w
+		if r <= acc {
+			k := c.Key
+			return &k
+		}
+	}
+	k := candidates[len(candidates)-1].Key
+	return &k
+}

internal/balancer/weighted_test.go

@@ -0,0 +1,32 @@
+package balancer_test
+
+import (
+	"testing"
+
+	"github.com/rose_cat707/luminary/internal/balancer"
+	"github.com/rose_cat707/luminary/internal/model"
+)
+
+func TestSelectWeighted(t *testing.T) {
+	candidates := []balancer.KeyCandidate{
+		{Key: model.ProviderKey{ID: 1, Name: "a"}, Weight: 1},
+		{Key: model.ProviderKey{ID: 2, Name: "b"}, Weight: 3},
+	}
+	counts := map[uint]int{}
+	for i := 0; i < 1000; i++ {
+		k := balancer.SelectWeighted(candidates)
+		if k == nil {
+			t.Fatal("nil key")
+		}
+		counts[k.ID]++
+	}
+	if counts[2] <= counts[1] {
+		t.Fatalf("expected heavier weight key selected more often: %v", counts)
+	}
+}
+
+func TestSelectWeightedEmpty(t *testing.T) {
+	if k := balancer.SelectWeighted(nil); k != nil {
+		t.Fatal("expected nil")
+	}
+}