Leave out the node's own copy only by kind and id, never by a shared target (issue 1945, review)

A unit or container of the node's own that shares only its name with a
module's resource is not the module's: dropped, its record became an orphan
the apply removes, stopping the module's unit (1945/AC17).

cmd/mesh-host/nodeagent.go

@@ -204,9 +204,11 @@ func declarationOf(cs ...delivery.Composed) (*declaration.Declaration, error) {
 }
 
 // ownWithout is the node's own composition without the resources a module's composition among modules also declares:
-// the same kind and id, or the same kind and target (a file at one path). It answers what it left out, as "<id> (<module>)".
+// the same kind and id. A resource that shares only its target (a unit or container of the same name, another id) is
+// not the module's, and stays: dropped, its record would be an orphan the apply removes, stopping the module's unit. It
+// answers what it left out, as "<id> (<module>)".
 func ownWithout(own delivery.Composed, modules []delivery.Composed) (delivery.Composed, []string) {
-	byID, byTarget := map[string]string{}, map[string]string{}
+	byID := map[string]string{}
 	for _, c := range modules {
 		if c.Module == "" {
 			continue
@@ -217,9 +219,6 @@ func ownWithout(own delivery.Composed, modules []delivery.Composed) (delivery.Co
 				continue
 			}
 			byID[string(r.Kind())+"\x00"+r.Identity()] = c.Module
-			if t := r.Target(); t != "" {
-				byTarget[string(r.Kind())+"\x00"+t] = c.Module
-			}
 		}
 	}
 	if len(byID) == 0 {
@@ -234,9 +233,6 @@ func ownWithout(own delivery.Composed, modules []delivery.Composed) (delivery.Co
 			continue
 		}
 		module, dup := byID[string(r.Kind())+"\x00"+r.Identity()]
-		if !dup && r.Target() != "" {
-			module, dup = byTarget[string(r.Kind())+"\x00"+r.Target()]
-		}
 		if dup {
 			dropped = append(dropped, fmt.Sprintf("%s (%s)", r.Identity(), module))
 			continue

cmd/mesh-host/whatruns_test.go

@@ -125,3 +125,15 @@ func TestTheKeptDeclarationsFilledPathsGoToTheirModules(t *testing.T) {
 		t.Errorf("a kept declaration that does not read split into %v", splitBy)
 	}
 }
+
+// 1945/AC17 (unit, review): a resource of the node's own that shares only its target with a module's (another id: a
+// unit or a container of the same name) is not the module's, and is neither dropped nor left to be removed.
+func TestASharedTargetWithAnotherIDIsNotDropped(t *testing.T) {
+	ownFile, _ := json.Marshal(map[string]any{"id": "host.zshrc", "type": "file", "path": "/tmp/r6/zsh/rc", "content": "x"})
+	own := delivery.Composed{Node: "n1", Resources: []json.RawMessage{ownFile}}
+	zsh := delivery.Composed{Node: "n1", Module: "zsh", FP: "src2:aa", Resources: []json.RawMessage{aFileOf("zsh", "rc")}}
+	trimmed, dropped := ownWithout(own, []delivery.Composed{zsh})
+	if len(dropped) != 0 || len(trimmed.Resources) != 1 {
+		t.Errorf("a resource sharing only its target was dropped: %v", dropped)
+	}
+}