From d295fd4250a7cb0ba6a2b79ab84eb71b64315a17 Mon Sep 17 00:00:00 2001
From: jochen <jschoubben@gmail.com>
Date: Wed, 21 Oct 2026 00:02:34 +0200
Subject: [PATCH] Say nothing serves a call only for the bus's own
 no-responders, never for a tool's error that mentions 503 (issue 1529)

---
 node-tools/internal/bus/bus.go                |  6 +++-
 node-tools/internal/console/client.go         |  6 ++--
 .../internal/console/noresponders_test.go     | 28 +++++++++++++++++++
 3 files changed, 37 insertions(+), 3 deletions(-)
 create mode 100644 node-tools/internal/console/noresponders_test.go

diff --git a/node-tools/internal/bus/bus.go b/node-tools/internal/bus/bus.go
index 84b3aa6..c864de3 100644
--- a/node-tools/internal/bus/bus.go
+++ b/node-tools/internal/bus/bus.go
@@ -708,12 +708,16 @@ var HandoverPause = 3 * time.Second
 // (mesh-controller internal/link, `"retry": "handing-over"`).
 const RetryHandingOver = "handing-over"
 
+// ErrNoResponders is the bus's own refusal: nothing subscribes to the subject asked. It is told apart
+// from a tool's own error by errors.Is, never by its text (a tool may say "503" itself, issue 1529).
+var ErrNoResponders = errors.New("503 no responders")
+
 // askOnce asks once, and says whether the answer was a refusal marked to be asked again.
 func (c *Conn) askOnce(subject string, data []byte) (Answered, bool, error) {
 	msg, err := c.nc.Request(subject, data, RequestTimeout)
 	if err != nil {
 		if errors.Is(err, nats.ErrNoResponders) {
-			return Answered{}, false, errors.New("503 no responders")
+			return Answered{}, false, ErrNoResponders
 		}
 		if errors.Is(err, nats.ErrTimeout) {
 			return Answered{}, false, errors.New("timeout")
diff --git a/node-tools/internal/console/client.go b/node-tools/internal/console/client.go
index 1b80b87..41fdeb5 100644
--- a/node-tools/internal/console/client.go
+++ b/node-tools/internal/console/client.go
@@ -7,6 +7,8 @@ import (
 	"regexp"
 	"strings"
 
+	"github.com/nats-io/nats.go"
+
 	"github.com/novox/mesh-tools/node-tools/internal/bus"
 )
 
@@ -109,7 +111,6 @@ func subjectListed(name, node string, l *Listing) string {
 }
 
 var (
-	noResponders = regexp.MustCompile(`(?i)no responders|503`)
 	// The bus's own two refusals, by their whole phrase. "authorization" alone also matched a tool's own
 	// answer that merely mentions the word — the runtime refusing a state value with an Authorization
 	// header (novox/hq ADR 0201) read as "this account may not call", which sent the reader the wrong way.
@@ -127,7 +128,8 @@ func whyItFailed(key string, err error) string {
 	}
 	msg := err.Error()
 	switch {
-	case noResponders.MatchString(msg):
+	// By type, not text: a tool's own error that mentions 503 is the tool's answer (issue 1529).
+	case errors.Is(err, bus.ErrNoResponders) || errors.Is(err, nats.ErrNoResponders):
 		extra := ""
 		if strings.HasPrefix(key, "seat:") {
 			extra = ", or nothing holds that seat"
diff --git a/node-tools/internal/console/noresponders_test.go b/node-tools/internal/console/noresponders_test.go
new file mode 100644
index 0000000..fd008c8
--- /dev/null
+++ b/node-tools/internal/console/noresponders_test.go
@@ -0,0 +1,28 @@
+package console
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+	"testing"
+
+	"github.com/nats-io/nats.go"
+
+	"github.com/novox/mesh-tools/node-tools/internal/bus"
+)
+
+// A tool's own error that mentions 503 is the tool's answer, not a routing fault (issue 1529).
+func TestAToolsOwn503IsNotNothingServes(t *testing.T) {
+	got := whyItFailed("scanner.scan", errors.New("the scanner refused the scan job: 503 Service Unavailable"))
+	if strings.Contains(got, "nothing serves") || !strings.HasPrefix(got, "scanner.scan failed: ") || !strings.Contains(got, "503") {
+		t.Fatalf("got %q", got)
+	}
+}
+
+func TestARealNoRespondersStillSaysNothingServes(t *testing.T) {
+	for _, err := range []error{bus.ErrNoResponders, fmt.Errorf("ask: %w", bus.ErrNoResponders), nats.ErrNoResponders} {
+		if got := whyItFailed("a.b", err); !strings.HasPrefix(got, "nothing serves a.b") {
+			t.Fatalf("%v: got %q", err, got)
+		}
+	}
+}