views: an ask through a tool reads the tool runner's {result, error} envelope

A5's request: the bus module's keeper asks the indexer's first view through the tool runner, which answers in that
envelope; its error is the ask's.

Claude-Session: https://claude.ai/code/session_01JG73KJNrH5EgFXMKKYSrig

go/views/follow.go

@@ -352,7 +352,8 @@ func (f *Follower) Gap(ctx context.Context, why string) error {
 	return f.askUntil(ctx, "a gap: "+why, false)
 }
 
-// AskVia is a Follower's Ask through a process's call of the owner's tool (process.Conn.Call), decoding its answer.
+// AskVia is a Follower's Ask through a call of the owner's tool (process.Conn.Call, or stdio.Ask through the tool
+// runner), decoding its answer: bare, or in the tool runner's envelope {result, error}, whose error is the ask's.
 func AskVia(call func(key string, body any) (json.RawMessage, error), tool string) func(context.Context, string) (Answer, error) {
 	return func(_ context.Context, after string) (Answer, error) {
 		body := map[string]any{}
@@ -363,6 +364,16 @@ func AskVia(call func(key string, body any) (json.RawMessage, error), tool strin
 		if err != nil {
 			return Answer{}, err
 		}
+		var wrapped struct {
+			Result json.RawMessage `json:"result"`
+			Error  string          `json:"error"`
+		}
+		if json.Unmarshal(raw, &wrapped) == nil && (len(wrapped.Result) > 0 || wrapped.Error != "") {
+			if wrapped.Error != "" {
+				return Answer{}, fmt.Errorf("%s answered: %s", tool, wrapped.Error)
+			}
+			raw = wrapped.Result
+		}
 		return DecodeAnswer(raw)
 	}
 }

go/views/views_test.go

@@ -260,6 +260,24 @@ func TestViews(t *testing.T) {
 			t.Errorf("asked again by hand: %v, %v", again, err)
 		}
 	})
+	t.Run("an ask through a tool reads the answer bare or in the tool runner's envelope, and its error", func(t *testing.T) {
+		bare := `{"v":1,"owner":"o","state":"s","revision":3,"values":{"k":"1"}}`
+		for name, c := range map[string]struct {
+			answer string
+			rev    uint64
+			err    string
+		}{
+			"bare":           {bare, 3, ""},
+			"in an envelope": {`{"result":` + bare + `}`, 3, ""},
+			"an error":       {`{"error":"not yet"}`, 0, "not yet"},
+		} {
+			ask := AskVia(func(string, any) (json.RawMessage, error) { return json.RawMessage(c.answer), nil }, "o.first_view")
+			a, err := ask(context.Background(), "")
+			if (c.err == "") != (err == nil) || (err != nil && !strings.Contains(err.Error(), c.err)) || a.Revision != c.rev {
+				t.Errorf("%s: %+v, %v", name, a, err)
+			}
+		}
+	})
 	t.Run("an event names its state on its subject, and decodes as it was encoded", func(t *testing.T) {
 		if s := StateOfEvent("mesh.stream.mesh-delivery-indexer.event.views.config-candidates"); s != "config-candidates" {
 			t.Errorf("state of subject = %q", s)