A login moves its node; an API key is added from any node, sealed (novox/hq ADR 0209)

The manager binds the node a login was adopted from to that login's licence,
switching it if it was bound to another; serves public_key; adopt takes a
key sealed to it. claude-code gains claude_code_add_api_key: read a file on
this node, seal, hand to adopt, remove the file, optionally switch here.

modules/claude-code/cmd/claude-code/claude_code_test.go

@@ -362,3 +362,40 @@ func TestABadEntryIsRefusedBeforeAnythingIsPut(t *testing.T) {
 		t.Fatal("another node's key changed this one")
 	}
 }
+
+// An API key goes to the manager sealed to its key, never in the clear, and its file is gone afterwards.
+func TestAnAPIKeyIsHandedOverSealedAndItsFileRemoved(t *testing.T) {
+	p, _ := node(t, "laptop")
+	manager, _ := GenerateKeyPair()
+	file := filepath.Join(p.Home, "api-key")
+	writeFile(t, file, "sk-ant-api03-secret\n")
+	var sent []string
+	ask := func(address string, args any) (json.RawMessage, error) {
+		raw, _ := json.Marshal(args)
+		sent = append(sent, address+" "+string(raw))
+		switch address {
+		case "seat:anthropic-licence-manager.public_key":
+			return json.Marshal(map[string]any{"public_key": manager.PublicKey})
+		case "seat:anthropic-licence-manager.adopt":
+			box := args.(map[string]any)["sealed"].(SealedBox)
+			if key, err := Open(box, manager.PrivateKey); err != nil || key != "sk-ant-api03-secret" {
+				t.Fatalf("the manager opened %q, %v", key, err)
+			}
+			return json.Marshal(map[string]any{"adopted": true})
+		case "seat:anthropic-licence-manager.switch":
+			return json.Marshal(map[string]any{"licence": "api"})
+		}
+		t.Fatalf("asked %s", address)
+		return nil, nil
+	}
+	out, err := AddAPIKey(p, "api", file, true, ask)
+	if err != nil || out["file"] != "removed" || out["switched"] == nil {
+		t.Fatalf("%v %v", out, err)
+	}
+	if _, err := os.Stat(file); !os.IsNotExist(err) {
+		t.Fatal("the key file is still there")
+	}
+	if strings.Contains(strings.Join(sent, "\n"), "sk-ant") {
+		t.Fatalf("the key crossed in the clear: %v", sent)
+	}
+}