add an early version of a UCAN client

toolkit/client/requester.go

@@ -0,0 +1,19 @@
+package client
+
+import (
+	"context"
+	"iter"
+
+	"github.com/ucan-wg/go-ucan/did"
+	"github.com/ucan-wg/go-ucan/pkg/command"
+	"github.com/ucan-wg/go-ucan/token/delegation"
+)
+
+type DelegationRequester interface {
+	// RequestDelegation retrieve a delegation or chain of delegation for the given parameters.
+	// - cmd: the command to execute
+	// - issuer: the DID of the client, also the issuer of the invocation token
+	// - audience: the DID of the resource to operate on, also the subject (or audience if defined) of the invocation token
+	// Note: the returned delegation(s) don't have to match exactly the parameters, as long as they allow them.
+	RequestDelegation(ctx context.Context, cmd command.Command, audience did.DID, subject did.DID) (iter.Seq2[*delegation.Bundle, error], error)
+}