feat: Fair Birth logic - allow 0 UMC self-delegation for validators at genesis

x/staking/keeper/msg_server.go

@@ -162,10 +162,10 @@ func (k msgServer) EditValidator(ctx context.Context, msg *types.MsgEditValidato
 		return nil, errorsmod.Wrap(sdkerrors.ErrInvalidRequest, "empty description")
 	}
 
-	if msg.MinSelfDelegation != nil && !msg.MinSelfDelegation.IsPositive() {
+	if msg.MinSelfDelegation != nil && msg.MinSelfDelegation.IsNegative() {
 		return nil, errorsmod.Wrap(
 			sdkerrors.ErrInvalidRequest,
-			"minimum self delegation must be a positive integer",
+			"minimum self delegation cannot be negative",
 		)
 	}
 

x/staking/types/msg.go

@@ -57,8 +57,15 @@ func (msg MsgCreateValidator) Validate(ac address.Codec) error {
 		return ErrEmptyValidatorPubKey
 	}
 
-	if !msg.Value.IsValid() {
+	// MUKAN FAIR BIRTH: Allow zero self-delegation at genesis.
-		return errorsmod.Wrap(sdkerrors.ErrInvalidRequest, "invalid delegation amount")
+	// Standard Cosmos SDK requires IsValid() which enforces IsPositive().
+	// Mukan Network allows validators to join with 0 UMC — they earn stake
+	// through PoJ mining after the network is live.
+	if err := sdk.ValidateDenom(msg.Value.Denom); err != nil {
+		return errorsmod.Wrap(sdkerrors.ErrInvalidRequest, "invalid delegation coin denom")
+	}
+	if msg.Value.Amount.IsNegative() {
+		return errorsmod.Wrap(sdkerrors.ErrInvalidRequest, "self delegation amount cannot be negative")
 	}
 
 	if msg.Description == (Description{}) {
@@ -80,6 +87,8 @@ func (msg MsgCreateValidator) Validate(ac address.Codec) error {
 		)
 	}
 
+	// MUKAN FAIR BIRTH: Zero self-delegation is valid — minimum is enforced at
+	// the PoJ level, not at the staking layer.
 	if msg.Value.Amount.LT(msg.MinSelfDelegation) {
 		return ErrSelfDelegationBelowMinimum
 	}