Read placement from a layer's Placement, never from its config values (issue 651)

ADR 0348 clause 11: places, accesses and kept networks are placement, not config.
Today's mergeable files still take them as said, so nothing composes differently.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

internal/catalogue/placement.go

@@ -34,6 +34,69 @@ const PlacesSetting = "places"
 // AccessesSetting is the settings key that says where a module's accesses are on this node, by id.
 const AccessesSetting = "accesses"
 
+// **Placement is not config** (novox/hq ADR 0348 clause 11, issue 651). `places`, `accesses` and
+// `networks` are facts of an assignment the controller decides, held beside the assignment and apart
+// from its settings: a Layer carries them in Placement, never in Values, and only Places, AccessPlaces
+// and KeptNetworks read them. A person still says them as keys of a layer through `settings`; LayerOf
+// splits such a layer, so what they type is routed to the placement and nothing they do changes.
+
+// placementKeys are the keys of a layer that are placement, not config.
+var placementKeys = map[string]bool{PlacesSetting: true, AccessesSetting: true, NetworksSetting: true}
+
+// SplitPlacement divides a layer as a person says it into its config values and its placement. Each is
+// nil when it holds nothing; the values themselves are not copied.
+func SplitPlacement(values map[string]any) (config, placement map[string]any) {
+	for key, value := range values {
+		if placementKeys[key] {
+			if placement == nil {
+				placement = map[string]any{}
+			}
+			placement[key] = value
+			continue
+		}
+		if config == nil {
+			config = map[string]any{}
+		}
+		config[key] = value
+	}
+	return config, placement
+}
+
+// LayerOf is a layer as a person says it — config values and placement in one map — split into the two.
+func LayerOf(from string, values map[string]any) Layer {
+	config, placement := SplitPlacement(values)
+	if config == nil {
+		config = map[string]any{}
+	}
+	return Layer{From: from, Values: config, Placement: placement}
+}
+
+// Whole is the layer as a person says it: its values and its placement in one map, a new map.
+func (l Layer) Whole() map[string]any {
+	out := make(map[string]any, len(l.Values)+len(l.Placement))
+	for k, v := range l.Values {
+		out[k] = v
+	}
+	for k, v := range l.Placement {
+		out[k] = v
+	}
+	return out
+}
+
+// asSaid is the layers with placement folded back into the values, for what reads a layer whole as it
+// did while placement was kept in it: today's mergeable file, which takes every key (ADR 0326 §3), and
+// the judgement that no value holds a line end.
+func asSaid(layers []Layer) []Layer {
+	out := make([]Layer, len(layers))
+	for i, l := range layers {
+		out[i] = l
+		if len(l.Placement) > 0 {
+			out[i] = Layer{From: l.From, Values: l.Whole(), Default: l.Default}
+		}
+	}
+	return out
+}
+
 // Placement is what an assignment says about one of a module's directories.
 type Placement struct {
 	// Path is where the directory is on this machine. Absolute.
@@ -208,7 +271,7 @@ func Places(m Manifest, layers []Layer) (map[string]Placement, error) {
 	}
 	out := map[string]Placement{}
 	for _, layer := range layers {
-		raw, ok := layer.Values[PlacesSetting]
+		raw, ok := layer.Placement[PlacesSetting]
 		if !ok {
 			continue
 		}
@@ -278,7 +341,7 @@ func AccessPlaces(m Manifest, layers []Layer) (map[string]string, error) {
 	}
 	out := map[string]string{}
 	for _, layer := range layers {
-		raw, ok := layer.Values[AccessesSetting]
+		raw, ok := layer.Placement[AccessesSetting]
 		if !ok {
 			continue
 		}