Let a trusted file that names its keys hold only those keys at the terminal (hq issue 586, ADR 0329 §5)

A module with a trusted mergeable file had its whole layer refused through the
settings verb, because such a file took any key. Once a module's files name the
keys they take (ADR 0326), each file takes only those, so only a trusted file's
named keys are the terminal's: betterbird's tags, in a file nothing trusts, is set
through the verb, while its accounts and identities stay the terminal's or the
operator's warrant. A module whose files name no keys keeps the whole-layer rule.

cmd/mesh-controller/terminal_settings_test.go

@@ -345,6 +345,37 @@ func TestAnyKeyOfAModuleWithATrustedMergeableFileIsRefusedThroughAVerb(t *testin
 	}
 }
 
+// A module whose mergeable files name the keys they take (ADR 0326): a key of a trusted file is refused through a
+// verb, and a key of a file nothing trusts is set through it (novox/hq ADR 0329 §5, issue 586: betterbird's tags).
+func TestOnlyATrustedFilesNamedKeyIsRefusedThroughAVerb(t *testing.T) {
+	open := aMesh(t)
+	ctx := t.Context()
+	register(t, open, catalogue.Manifest{Module: "mailer", Version: "1",
+		Resources: []map[string]any{
+			{"id": "accounts", "type": "file", "path": "/var/lib/mailer/accounts.json", "mode": "0600", "merge": "json",
+				"trusted": true, "takes-settings": []any{"accounts"}, "content": `{"accounts": {}}`},
+			{"id": "tags", "type": "file", "path": "/var/lib/mailer/tags.json", "mode": "0644", "merge": "json",
+				"trusted": false, "takes-settings": []any{"tags"}, "content": `{"tags": {}}`}}})
+	if _, err := assign(ctx, open, "anchor", "mailer"); err != nil {
+		t.Fatal(err)
+	}
+	if err := throughVerb(t, "settings", map[string]any{"module": "mailer", "values": `{"tags":{"todo":{"name":"To do"}}}`}); err != nil {
+		t.Fatalf("a key of a file nothing trusts is the verb's: %v", err)
+	}
+	err := throughVerb(t, "settings", map[string]any{"module": "mailer", "replace": "true",
+		"values": `{"tags":{"todo":{"name":"To do"}},"accounts":{"mail":{"address":"me@mail.example"}}}`})
+	if err == nil || !strings.Contains(err.Error(), "controller's terminal") || !strings.Contains(err.Error(), "accounts") {
+		t.Fatalf("a key of a trusted file is the terminal's: %v", err)
+	}
+	values, _, err := open.inventory.Layer(ctx, "", "mailer")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if raw, _ := json.Marshal(values); string(raw) != `{"tags":{"todo":{"name":"To do"}}}` {
+		t.Fatalf("the layer holds the tags alone: %s", raw)
+	}
+}
+
 // Who owns a module's directory is said at the terminal alone (novox/hq issue 279): a directory's owner may name
 // the settings the module runs as, root chowns the folder to them at the next push, and through the settings verb
 // any caller could have set puid to 0 or to its own uid. The key is refused through every verb route even where a

internal/catalogue/terminal_keys.go

@@ -33,6 +33,10 @@ import (
 //  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.
+//     **Unless the module's files name the keys they take** (novox/hq ADR 0326, ADR 0329 §5): then a mergeable
+//     file takes exactly its `takes-settings` and no other key, so those keys of a trusted file are terminal keys
+//     and the rest of the layer is not. A key no file names is stray and refused where it is set. So betterbird's
+//     `tags`, in a file nothing trusts, is set through the verb, while its `accounts` and `identities` are not.
 //  5. **Every setting a directory's owner asks for** (novox/hq issue 279): root chowns the directory to the number
 //     at the next push, so through a verb any caller could hand itself — or uid 0 — a module's folder. Whatever
 //     else asks for the key, a file marked `"trusted": false` included, the owner makes it the terminal's.
@@ -109,8 +113,13 @@ func UnsaidTrust(m Manifest) []string {
 // 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.
+// layer set at the controller's terminal; a verb may read it and change nothing. A module whose mergeable files
+// name the keys they take (ADR 0326) has none here: each such file takes only its named keys, which TerminalKeys
+// holds for a trusted one (ADR 0329 §5).
 func TrustedMergeable(m Manifest) []string {
+	if namesItsKeys(m) {
+		return nil
+	}
 	var out []string
 	for _, r := range m.Resources {
 		if fmt.Sprint(r["type"]) != "file" {
@@ -135,6 +144,16 @@ func TrustedMergeable(m Manifest) []string {
 func asksFor(r map[string]any) []string {
 	content, _ := r["content"].(string)
 	asked := settingsUsed(content)
+	if how, _ := r["merge"].(string); how != "" {
+		if taken, names := takenKeys(r); names {
+			// The file takes exactly the keys it names (ADR 0326), whatever its content holds.
+			for key := range taken {
+				asked = append(asked, key)
+			}
+			sort.Strings(asked)
+			return asked
+		}
+	}
 	if how, _ := r["merge"].(string); how != "" && strings.TrimSpace(content) != "" {
 		var base map[string]any
 		if json.Unmarshal([]byte(content), &base) == nil {

internal/catalogue/terminal_settings_test.go

@@ -166,6 +166,33 @@ func TestTerminalKeysAreDerived(t *testing.T) {
 	}
 }
 
+// A module whose mergeable files name the keys they take (ADR 0326) has no whole layer at the terminal: a
+// trusted file's named keys are terminal keys, and a file nothing trusts leaves its keys to the verb (novox/hq
+// ADR 0329 §5, issue 586: betterbird's tags beside its trusted accounts, identities, calendars, address books
+// and filters). A module whose files name no keys keeps the whole layer at the terminal (issue 340).
+func TestOnlyANamedKeyOfATrustedFileIsTheTerminals(t *testing.T) {
+	betterbird := Manifest{Module: "betterbird", Resources: []map[string]any{
+		{"id": "prefs", "type": "file", "path": "/home/p/prefs.json", "merge": MergeJSON, "trusted": true,
+			TakesSettingsField: []any{"prefs"}, "content": `{"prefs": {}}`},
+		{"id": "accounts", "type": "file", "path": "/home/p/accounts.json", "merge": MergeJSON, "trusted": true,
+			TakesSettingsField: []any{"accounts"}, "content": `{"accounts": {}}`},
+		{"id": "configuration", "type": "file", "path": "/home/p/configuration.json", "merge": MergeJSON,
+			TakesSettingsField: []any{"identities", "calendars", "address-books", "filters"}, "content": `{}`},
+		{"id": "tags", "type": "file", "path": "/home/p/tags.json", "merge": MergeJSON, "trusted": false,
+			TakesSettingsField: []any{"tags"}, "content": `{"tags": {}}`}}}
+	if got := TrustedMergeable(betterbird); len(got) != 0 {
+		t.Fatalf("files that name their keys put no whole layer at the terminal: %v", got)
+	}
+	if got := strings.Join(TerminalKeys(betterbird), ","); got != "places,accesses,accounts,address-books,calendars,filters,identities,prefs" {
+		t.Fatalf("the named keys of the trusted files, unmarked counting as trusted, and not tags: %s", got)
+	}
+	silent := Manifest{Module: "keycloak", Resources: []map[string]any{{"id": "runtime", "type": "file",
+		"path": "/var/lib/kc/runtime.json", "merge": MergeJSON, "content": `{}`}}}
+	if got := TrustedMergeable(silent); len(got) != 1 {
+		t.Fatalf("a file that names no keys still takes any key, so its module's layer stays the terminal's: %v", got)
+	}
+}
+
 // A file that asks for a setting says whether what it asks is trusted (novox/hq issue 339): `trusted` is a
 // boolean, on a file alone, and a file asking for a setting without it is named.
 func TestAFileSaysWhetherItsSettingsAreTrusted(t *testing.T) {

testdata/store-tests

@@ -39,3 +39,4 @@
 ./internal/inventory TestAWalksRestIsReadFromEachMachinesOwnSend
 ./internal/inventory TestAStoredBuildWithASilentMergeableFileIsStillReadAndComposed
 ./cmd/mesh-controller TestPlanAndNodeListAnOptionalRequirementLeftUnbound
+./cmd/mesh-controller TestOnlyATrustedFilesNamedKeyIsRefusedThroughAVerb