Refuse a provision's value unless the vault's credential name and generation are the ones its reference names (issue 1954 L6-E1; ADR 0570 clauses 1, 6)

The value written is the one the provision names: a1-47 makes Reference.ID the vault's credential name. A mismatch in
either refuses the write, naming both. Test: a row in TestAWriteAndAnApplyOfTheSameFileSerialise.

cmd/mesh-host/filling_test.go

@@ -50,6 +50,7 @@ func TestAWriteAndAnApplyOfTheSameFileSerialise(t *testing.T) {
 	// The provision m reads, as mesh-provisioner keeps it, and the vault's value of it, sealed to this machine (faked:
 	// the opener reads the box's "v").
 	provision := map[string]string{}
+	vaultName := "provision/postgres/db"
 	secrets := provisionSecrets{node: "n1",
 		read: func(_ context.Context, key string) ([]byte, bool, error) {
 			v, ok := provision[key]
@@ -60,7 +61,7 @@ func TestAWriteAndAnApplyOfTheSameFileSerialise(t *testing.T) {
 			var a struct{ Credentials []map[string]any }
 			_ = json.Unmarshal(raw, &a)
 			c := a.Credentials[0]
-			c["generation"], c["sealed"] = 2, map[string]string{"v": "s3cret"}
+			c["name"], c["generation"], c["sealed"] = vaultName, 2, map[string]string{"v": "s3cret"}
 			return json.Marshal(map[string]any{"node": "n1", "credentials": []any{c}})
 		},
 		open: func(sealed string) ([]byte, error) {
@@ -149,9 +150,12 @@ func TestAWriteAndAnApplyOfTheSameFileSerialise(t *testing.T) {
 		content     string
 		want        string // the file after; "" keeps what was there
 		mode        os.FileMode
+		vault       string // the vault's credential name, when not the one the provision names
 	}{
 		{name: "a provision not provided is refused", state: provisions.Asked, content: "password=${secret:db}\n"},
 		{name: "provided with no reference is refused", state: provisions.Provided, content: "password=${secret:db}\n"},
+		{name: "the vault's value is another than the provision names", state: provisions.Provided, ref: true,
+			vault: "pair/n2/db/n1/m", content: "password=${secret:db}\n"},
 		{name: "provided: filled at the write, 0600", state: provisions.Provided, ref: true,
 			content: "password=${secret:db}\n", want: "password=s3cret\n", mode: 0o600},
 		{name: "no placeholder is written as it came, as the declaration says", content: "plain\n", want: "plain\n", mode: 0o644},
@@ -160,6 +164,10 @@ func TestAWriteAndAnApplyOfTheSameFileSerialise(t *testing.T) {
 		if tc.state != "" {
 			provision["n1.m.db"] = keyed(tc.state, tc.ref)
 		}
+		vaultName = "provision/postgres/db"
+		if tc.vault != "" {
+			vaultName = tc.vault
+		}
 		a := e.Write(context.Background(), uid, filling.Request{Path: path, Content: []byte(tc.content)})
 		got, _ := os.ReadFile(path)
 		if tc.want == "" {

cmd/mesh-host/provision_secrets.go

@@ -108,6 +108,7 @@ func (p provisionSecrets) value(ctx context.Context, module, provision, local st
 		Node        string `json:"node"`
 		Credentials []struct {
 			asked
+			Name       string          `json:"name"`
 			Generation int             `json:"generation"`
 			Sealed     json.RawMessage `json:"sealed"`
 		} `json:"credentials"`
@@ -122,9 +123,10 @@ func (p provisionSecrets) value(ctx context.Context, module, provision, local st
 		if c.asked != ask {
 			continue
 		}
-		if c.Generation < pr.Reference.Generation {
-			return nil, fmt.Errorf("the vault holds %s at generation %d and the provision names %d: not written until it has it",
-				key, c.Generation, pr.Reference.Generation)
+		// The value the provision names, by the vault's credential name and its generation (clause 6): another is refused.
+		if c.Name != pr.Reference.ID || c.Generation != pr.Reference.Generation {
+			return nil, fmt.Errorf("the vault answered %s generation %d for %s, and the provision names %s generation %d: "+
+				"nothing is written until they agree", c.Name, c.Generation, key, pr.Reference.ID, pr.Reference.Generation)
 		}
 		value, err := p.open(string(c.Sealed))
 		if err != nil {