Serve the read verbs on the serving controller's own connection, and name every connection

Each verb ran as a process that dialled the bus, so hundreds of short
connections an hour, all named mesh-controller, hid any client reconnecting
in a loop (hq issue 327). D15 now says a user whose connections keep dropping.

cmd/mesh-controller/seatverbs.go

@@ -7,6 +7,7 @@ import (
 	"errors"
 	"fmt"
 	"github.com/nats-io/nats.go/micro"
+	"io"
 	"os"
 	"os/exec"
 	"slices"
@@ -28,6 +29,9 @@ import (
 // answer. It also means a refusal is the same refusal in the same words, because it is the same
 // output.
 
+// verbKey carries the verb a call is for, to the process it runs.
+type verbKey struct{}
+
 // verbAnswer is what a verb answers: what the command printed, whether it succeeded, and — where the
 // command speaks JSON — the same as data.
 type verbAnswer struct {
@@ -921,6 +925,12 @@ func runVerb(ctx context.Context, argv []string) (verbAnswer, error) {
 		caller = "a seat call whose caller the bus did not name"
 	}
 	cmd.Env = append(cmd.Env, link.CallerVar+"="+caller+", through the "+catalogue.ControllerSeatName+" seat")
+	// And which verb, so the connection it dials says so in the bus's list (novox/hq issue 327).
+	verb, _ := ctx.Value(verbKey{}).(string)
+	if verb == "" {
+		verb = argv[0]
+	}
+	cmd.Env = append(cmd.Env, verbVar+"="+verb)
 	// Two buffers, one answer. What the command *says* is both streams, in the order a person at
 	// a shell would read them; what it *answers as data* is standard output alone — `status --json`
 	// prints its warnings beside the document, and a JSON parsed from the two together parsed
@@ -929,18 +939,7 @@ func runVerb(ctx context.Context, argv []string) (verbAnswer, error) {
 	cmd.Stdout = &stdout
 	cmd.Stderr = &stderr
 	runErr := cmd.Run()
-	answer := verbAnswer{Output: stdout.String() + stderr.String(), OK: runErr == nil}
-	if jsonVerbs[argv[0]] && runErr == nil {
-		var parsed any
-		if json.Unmarshal(bytes.TrimSpace(stdout.Bytes()), &parsed) == nil {
-			answer.Answer = parsed
-			if overviewVerbs[argv[0]] {
-				// Once, as data: the same document again as text doubled an answer that already
-				// outgrew one message of the bus (novox/hq issue 314).
-				answer.Output = stderr.String() + "its answer, as data, is `answer`\n"
-			}
-		}
-	}
+	answer := answerOf(argv, stdout.Bytes(), stderr.String(), runErr == nil)
 	var exit *exec.ExitError
 	if runErr != nil && !errors.As(runErr, &exit) {
 		// Not the command refusing — the command not running at all, which is this process's fault.
@@ -955,6 +954,66 @@ func runVerb(ctx context.Context, argv []string) (verbAnswer, error) {
 	return answer, nil
 }
 
+// answerOf is what a command said, as a verb answers it: both streams as text, and standard output as data
+// where the command speaks JSON.
+func answerOf(argv []string, stdout []byte, stderr string, ok bool) verbAnswer {
+	answer := verbAnswer{Output: string(stdout) + stderr, OK: ok}
+	if jsonVerbs[argv[0]] && ok {
+		var parsed any
+		if json.Unmarshal(bytes.TrimSpace(stdout), &parsed) == nil {
+			answer.Answer = parsed
+			if overviewVerbs[argv[0]] {
+				// Once, as data: the same document again as text doubled an answer that already
+				// outgrew one message of the bus (novox/hq issue 314).
+				answer.Output = stderr + "its answer, as data, is `answer`\n"
+			}
+		}
+	}
+	return answer
+}
+
+// readHere answers a verb that only reads the bus in the serving controller itself, on its own connection
+// and keeper (novox/hq issue 327): the same command, writing to the answer rather than to a process's
+// output, so the answer is the one the command prints. False for any other command line, which runs as a
+// command of its own. Every `conditions` call — the operator's channel reads it at least once a minute —
+// was a process that dialled the bus, logged in and left.
+func readHere(ctx context.Context, argv []string) (verbAnswer, bool) {
+	var read func(context.Context, []string, io.Writer) error
+	args := argv[1:]
+	// Each where this process holds what it reads: the serving keeper, the hand-act log's connection, the
+	// serving connection.
+	switch argv[0] {
+	case "conditions":
+		sub := "list"
+		if len(args) > 0 && !strings.HasPrefix(args[0], "-") {
+			sub, args = args[0], args[1:]
+		}
+		if conditionsFrom != nil {
+			read = map[string]func(context.Context, []string, io.Writer) error{
+				"list": listConditions, "show": showCondition, "history": conditionHistory}[sub]
+		}
+	case "hand-acts":
+		if handActConn != nil || servingBus.Load() != nil {
+			read = listHandActs
+		}
+	case "queue":
+		if servingBus.Load() != nil {
+			read = listQueue
+		}
+	}
+	if read == nil {
+		return verbAnswer{}, false
+	}
+	var out bytes.Buffer
+	stderr := ""
+	err := read(ctx, args, &out)
+	if err != nil {
+		// As the command says it when it fails (main).
+		stderr = "mesh-controller: " + err.Error() + "\n"
+	}
+	return answerOf(argv, out.Bytes(), stderr, err == nil), true
+}
+
 // seatToolHandlers are the handlers for every verb the mesh-controller seat declares, from the
 // store's row, so a verb the row does not carry is not served. A verb it carries that this binary
 // cannot run is named at start and answers the reason when called — never a refusal to serve, which
@@ -1038,6 +1097,7 @@ func seatToolHandlers() (map[string]link.ToolHandler, []string, error) {
 			if err != nil {
 				return nil, err
 			}
+			ctx = context.WithValue(ctx, verbKey{}, verb)
 			if verb == "status" && statusFrom != nil {
 				// At once, from the summary the serving controller keeps (novox/hq to-be 45 Phase 0).
 				return statusFrom.answer(ctx)
@@ -1046,6 +1106,9 @@ func seatToolHandlers() (map[string]link.ToolHandler, []string, error) {
 				// Whatever it did, `status` is composed again once it has.
 				defer statusFrom.nudge()
 			}
+			if answer, read := readHere(ctx, argv); read {
+				return answer, nil
+			}
 			if answersFirst(argv) {
 				// Before anything is sent: a push sends the bus's own machine first, and a broker
 				// reloading its user list forgets the answer it was about to permit (novox/hq issue 265).