ADR 0627 §2: a holder reads its caller list as mesh-config resolved it, not from an environment nothing sets

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

go/caller_test.go

@@ -145,6 +145,13 @@ func TestACallerInTheArgumentsIsNeverTheCaller(t *testing.T) {
 	if d, _ := ParseVerbCallers(" ", nil, VerbCallers{"publish": {"x"}}); len(d["publish"]) != 1 {
 		t.Error("an empty value is not the holder's defaults")
 	}
+	// As mesh-config resolves the value: the object itself, or written as a string; null is the defaults.
+	for _, raw := range []string{`{"publish":["a"]}`, `"{\"publish\":[\"a\"]}"`, `null`} {
+		c, err := parseConfiguredVerbCallers(json.RawMessage(raw), []string{"publish"}, VerbCallers{"publish": {"a"}})
+		if err != nil || c.Allowed("publish", "ace.a") != nil {
+			t.Errorf("the config value %s read as %v, %v", raw, c, err)
+		}
+	}
 	if ModuleOf("ace.mesh-build-go") != "mesh-build-go" {
 		t.Error("ModuleOf does not read the module of a proved caller")
 	}

go/callers.go

@@ -110,3 +110,22 @@ func ModuleOf(proved string) string {
 	}
 	return proved
 }
+
+// ConfiguredVerbCallers is the holder's list as mesh-config resolved its config value key for this machine (Config):
+// a JSON object of verb to callers, or that object written as a string; an unset or empty value is defaults. A value
+// that cannot be read is an error, never the defaults, so a broken list is said, not widened.
+func ConfiguredVerbCallers(key string, verbs []string, defaults VerbCallers) (VerbCallers, error) {
+	raw, err := Config(key)
+	if err != nil {
+		return nil, fmt.Errorf("the config value %s cannot be read: %w", key, err)
+	}
+	return parseConfiguredVerbCallers(raw, verbs, defaults)
+}
+
+func parseConfiguredVerbCallers(raw json.RawMessage, verbs []string, defaults VerbCallers) (VerbCallers, error) {
+	var text string
+	if err := json.Unmarshal(raw, &text); err == nil || len(bytes.TrimSpace(raw)) == 0 || string(bytes.TrimSpace(raw)) == "null" {
+		return ParseVerbCallers(text, verbs, defaults)
+	}
+	return ParseVerbCallers(string(raw), verbs, defaults)
+}