The Go SDK subscribes and asks through the runtime (hq ADR 0198)

Subscribe(pattern, handler) asks the runtime for the module's events and answers each mesh/event
only after the matching handlers returned nil, so the runtime acknowledges it on the bus then and
not before; Ask(key, body) calls a tool as the module. Topic matching is the TypeScript SDK's.

go/stdio_test.go

@@ -3,6 +3,7 @@ package stdio
 import (
 	"bufio"
 	"encoding/json"
+	"errors"
 	"io"
 	"testing"
 	"time"
@@ -66,3 +67,75 @@ func TestABundleEmitsThroughTheRuntimeAndServesAsItsModule(t *testing.T) {
 	}
 	_ = inW.Close()
 }
+
+// A Go bundle subscribes and asks through the runtime (novox/hq ADR 0198): the event is answered only
+// after the handler took it, a handler's error is answered as one, and a tool call is asked as the module.
+func TestABundleSubscribesAndAsksThroughTheRuntime(t *testing.T) {
+	t.Setenv(ServedAs, "watcher")
+	inR, inW := io.Pipe()
+	outR, outW := io.Pipe()
+	ready := make(chan struct{})
+	go func() {
+		_ = ServeOn("", []Tool{{Name: "start", Run: func(map[string]any) (any, error) {
+			go func() {
+				_ = Subscribe("database.*", func(e Envelope) error {
+					if e.Key == "database.bad" {
+						return errors.New("not taken")
+					}
+					return nil
+				})
+				close(ready)
+			}()
+			answer, err := Ask("postgres.list", map[string]any{})
+			return json.RawMessage(answer), err
+		}}}, inR, outW)
+	}()
+	lines := bufio.NewScanner(outR)
+	next := func() map[string]any {
+		done := make(chan map[string]any, 1)
+		go func() {
+			if lines.Scan() {
+				var m map[string]any
+				_ = json.Unmarshal(lines.Bytes(), &m)
+				done <- m
+			}
+		}()
+		select {
+		case m := <-done:
+			return m
+		case <-time.After(3 * time.Second):
+			t.Fatal("the bundle said nothing")
+			return nil
+		}
+	}
+	send := func(m map[string]any) { b, _ := json.Marshal(m); _, _ = inW.Write(append(b, '\n')) }
+	send(map[string]any{"jsonrpc": "2.0", "id": 1, "method": "tools/call", "params": map[string]any{"name": "start"}})
+	// Two asks arrive, in either order: the subscription and the tool call.
+	asked := map[string]map[string]any{}
+	for len(asked) < 2 {
+		m := next()
+		asked[m["method"].(string)] = m
+	}
+	sub, ask := asked["mesh/subscribe"], asked["mesh/ask"]
+	if sub["params"].(map[string]any)["pattern"] != "database.*" || ask["params"].(map[string]any)["key"] != "postgres.list" {
+		t.Fatalf("asked %v", asked)
+	}
+	send(map[string]any{"jsonrpc": "2.0", "id": sub["id"], "result": map[string]any{}})
+	send(map[string]any{"jsonrpc": "2.0", "id": ask["id"], "result": []string{"a", "b"}})
+	if r := next(); r["id"] != float64(1) || r["result"].(map[string]any)["content"].([]any)[0].(map[string]any)["text"] != `["a","b"]` {
+		t.Fatalf("the call answered %v", r)
+	}
+	<-ready
+	send(map[string]any{"jsonrpc": "2.0", "id": 7, "method": "mesh/event", "params": map[string]any{"envelope": map[string]any{"key": "database.provisioned", "node": "anchor", "body": map[string]any{}}}})
+	if r := next(); r["id"] != float64(7) || r["error"] != nil {
+		t.Errorf("a taken event was answered %v", r)
+	}
+	send(map[string]any{"jsonrpc": "2.0", "id": 8, "method": "mesh/event", "params": map[string]any{"envelope": map[string]any{"key": "database.bad", "node": "anchor", "body": map[string]any{}}}})
+	if r := next(); r["id"] != float64(8) || r["error"] == nil {
+		t.Errorf("a refused event was answered %v, want an error so the runtime does not acknowledge it", r)
+	}
+	_ = inW.Close()
+	if !TopicMatches("a.#", "a.b.c") || TopicMatches("a.*", "a.b.c") || !TopicMatches("#", "x") {
+		t.Error("topic matching differs from the TypeScript SDK's")
+	}
+}