Refuse any change through a verb to a module with a trusted mergeable file

A mergeable file takes any key, not only those its content names, so an
empty runtime configuration a provider reads took a url of the caller's
through the settings verb (hq issue 340 review).

internal/catalogue/terminal_keys.go

@@ -30,6 +30,10 @@ import (
 //     managed settings and tool servers every Claude Code session on a node obeys in one, and through a verb an
 //     agent could have given every person's session a hook of its own.
 //
+//  4. **A module's whole layer, when it has a mergeable file not marked `"trusted": false`** (novox/hq issue 340,
+//     TrustedMergeable). A mergeable file takes any key a layer sets, not only those its content names, so no list
+//     of keys covers it: an empty runtime configuration a provider reads would take a `url` of the caller's.
+//
 // Derived from the manifest, never listed by hand, so a provider or a trusted file added tomorrow is covered.
 
 // TrustedField is the key a file resource carries to say whether the settings it asks for are trusted: true, or
@@ -92,6 +96,28 @@ func UnsaidTrust(m Manifest) []string {
 	return out
 }
 
+// TrustedMergeable is every mergeable file of a module not marked `"trusted": false`, by id (novox/hq issue 340).
+// A mergeable file takes any key a layer sets, not only those its content names: an empty runtime configuration a
+// provider reads takes a `url` of a caller's as surely as a declared one. So a module holding one has its whole
+// layer set at the controller's terminal; a verb may read it and change nothing.
+func TrustedMergeable(m Manifest) []string {
+	var out []string
+	for _, r := range m.Resources {
+		if fmt.Sprint(r["type"]) != "file" {
+			continue
+		}
+		if how, _ := r["merge"].(string); how == "" {
+			continue
+		}
+		if trusted, said := r[TrustedField].(bool); said && !trusted {
+			continue
+		}
+		out = append(out, fmt.Sprint(r["id"]))
+	}
+	sort.Strings(out)
+	return out
+}
+
 // asksFor is every setting a file resource asks for: each `${setting:…}` in its content and, for a mergeable file,
 // every key at the top of the content it merges into (novox/hq issue 340). Those are the keys the file declares it
 // takes: a layer's value for one of them lands in it as surely as a placeholder would be filled. A key the content