fix: BIGSERIAL pk models must be bun autoincrement (id=0 pkey collisions)

bun sends an explicit zero pk unless the field is tagged autoincrement, so the first PlanPrice/GatewayPayment/Refund row landed as id=0 and the second INSERT died on plan_prices_pkey (found by running scripts/seed against a live database). Tags the three int64 BIGSERIAL pks, returns the generated id on CreateRefund, and pins the rule in TestBigSerialPKsAreAutoIncrement.

Author: thanhan92-f1

internal/model/refund.go

@@ -70,7 +70,7 @@ type Refund struct {
 
 	// ID is the BIGSERIAL row id — the model keeps int64 (like
 	// GatewayPayment) because the ledger's own ids stay uuid TEXT.
-	ID      int64  `bun:",pk" json:"id"`
+	ID      int64  `bun:",pk,autoincrement" json:"id"`
 	OrderID string `bun:",notnull" json:"order_id"`
 	// PaymentProvider is one of the RefundProvider* values.
 	PaymentProvider string `bun:",notnull,default:''" json:"payment_provider"`

internal/store/bigserial_autoincr_test.go

@@ -0,0 +1,38 @@
+package store
+
+import (
+	"reflect"
+	"strings"
+	"testing"
+
+	"github.com/hitechcloud-vietnam/hitechcloud_keygate_licensing/internal/model"
+)
+
+// BIGSERIAL rows pin: every int64 primary key backed by a Postgres
+// BIGSERIAL MUST carry the `autoincrement` bun tag. Without it bun
+// sends an explicit id=0 in the INSERT column list — the first row
+// lands as id 0 and the second INSERT dies on plan_prices_pkey (seen
+// live in the seed run against a real database). TEXT/uuid keys
+// generate their ids in the app and are unaffected.
+func TestBigSerialPKsAreAutoIncrement(t *testing.T) {
+	cases := []any{
+		PlanPrice{},
+		GatewayPayment{},
+		model.Refund{},
+	}
+	for _, m := range cases {
+		typ := reflect.TypeOf(m)
+		field, ok := typ.FieldByName("ID")
+		if !ok {
+			t.Errorf("%s has no ID field", typ.Name())
+			continue
+		}
+		tag := field.Tag.Get("bun")
+		if !strings.Contains(tag, "pk") {
+			t.Errorf("%s.ID bun tag %q lacks pk", typ.Name(), tag)
+		}
+		if !strings.Contains(tag, "autoincrement") {
+			t.Errorf("%s.ID bun tag %q lacks autoincrement — bun would insert id=0 explicitly and collide on the second row", typ.Name(), tag)
+		}
+	}
+}

internal/store/gateway_payments.go

@@ -28,7 +28,7 @@ import (
 type GatewayPayment struct {
 	bun.BaseModel `bun:"table:gateway_payments"`
 
-	ID          int64          `bun:",pk" json:"id"`
+	ID          int64          `bun:",pk,autoincrement" json:"id"`
 	OrderID     string         `bun:",notnull" json:"order_id"`
 	Provider    string         `bun:",notnull" json:"provider"`
 	ProviderRef string         `bun:",notnull" json:"provider_ref"`

internal/store/plan_prices.go

@@ -34,7 +34,7 @@ import (
 type PlanPrice struct {
 	bun.BaseModel `bun:"table:plan_prices"`
 
-	ID            int64     `bun:",pk" json:"id"`
+	ID            int64     `bun:",pk,autoincrement" json:"id"`
 	PlanID        string    `bun:",notnull" json:"plan_id"`
 	Currency      string    `bun:",notnull" json:"currency"`
 	AmountMinor   int64     `bun:",notnull" json:"amount_minor"`
@@ -76,8 +76,10 @@ func curFoldCurrency(raw string) string {
 //   - the plan must exist (ErrPlanPricePlanNotFound) and the currency
 //     must be a shaped ISO code (curValidCurrency).
 //
-// The model's ID is the BIGSERIAL row id; a caller leaves it zero on
-// create and the upsert ignores it (the conflict target decides).
+// The model's ID is the BIGSERIAL row id; `autoincrement` keeps bun
+// from sending an explicit zero on insert (which would pin every row
+// to id 0 and collide on the second one), and the conflict target
+// decides the upsert semantics.
 func (s *Store) SetPlanPrice(ctx context.Context, p *PlanPrice) error {
 	if p == nil {
 		return errors.New("plan price is required")

internal/store/refunds.go

@@ -60,7 +60,7 @@ func (s *Store) CreateRefund(ctx context.Context, r *model.Refund) error {
 	if r == nil {
 		return errors.New("refund is required")
 	}
-	_, err := s.DB.NewInsert().Model(r).Exec(ctx)
+	_, err := s.DB.NewInsert().Model(r).Returning("id").Exec(ctx)
 	return err
 }