Apply the plan's credential form only to an offer that declares a credential (issue 825)

go/provider/provider.go

@@ -476,8 +476,11 @@ func (p *Provider) answer(ctx context.Context, e Entry, have []byte) Outcome {
 	e.Values = values
 	var credential []byte
 	// The plan's form wins; the offer's is the default.
+	// An offer that declares no credential has none whatever the plan says: the controller writes "pair" for it.
 	form := e.CredentialForm
-	if form == "" {
+	if offer.Credential == NoCredential {
+		form = ""
+	} else if form == "" {
 		form = map[CredentialForm]string{Shared: "shared", PerConsumer: "pair"}[offer.Credential]
 	}
 	switch form {

go/provider/provider_test.go

@@ -710,10 +710,6 @@ func TestThePlansCredentialFormWinsOverTheOffers(t *testing.T) {
 		"pair/novox/postgres-database/ace/letta" || e.User != "mesh_ace_letta" {
 		t.Fatalf("pair over shared: %+v", e)
 	}
-	if e := run(NoCredential, map[string]string{"credential-form": "pair"}); e.VaultName !=
-		"pair/novox/postgres-database/ace/letta" {
-		t.Fatalf("pair over none: %+v", e)
-	}
 	for _, form := range []string{"issued", "given"} {
 		if e := run(PerConsumer, map[string]string{"credential-form": form, "name": "main"}); e.VaultName !=
 			"provision/novox/postgres-database/ace/letta" || e.User != "mesh_ace_letta" {
@@ -784,3 +780,24 @@ func TestAFailedMakeIsSaidWithoutTheCredentialInAnyOfItsForms(t *testing.T) {
 		}
 	}
 }
+
+// An offer that declares no credential is answered with none whatever form the plan says (the controller writes
+// "pair" for such an offer): no vault name, and the Vault is never asked, so a provider with no Vault works (issue 825,
+// finding 4; issue 923).
+func TestAnOfferWithNoCredentialIgnoresThePlansForm(t *testing.T) {
+	bus := newStandIn()
+	b := bind("route", "", "novox", "route-proxy")
+	b["credential-form"] = "pair"
+	assign(t, bus, "ace", "letta", b)
+	p := New(Options{Node: "novox", Module: "route-proxy", Bus: bus, Logf: func(string, ...any) {},
+		Offers: map[string]Offer{"route": {Credential: NoCredential}}})
+	out, err := p.Pass(context.Background())
+	if err != nil || len(out) != 1 || out[0].Status != Answered {
+		t.Fatalf("%v %+v", err, out)
+	}
+	var e Entry
+	if err := json.Unmarshal(bus.get(BucketOf("route-proxy"), "ace.letta.route"), &e); err != nil || e.VaultName != "" ||
+		e.User != "" {
+		t.Fatalf("%v %+v", err, e)
+	}
+}