Add multi-address fallback for node connectivity

NodeConfig and MasterNodeConfig gain an optional addresses[] field
for fallback addresses tried in order after the primary address.
Provides resilience when Tailscale DNS is down or a node is only
reachable via LAN.

- dialAgentMulti: tries each address with a 3s health check, returns
  first success
- forEachNode: uses multi-address dialing
- AgentPool.AddNodeMulti: master tries all addresses when connecting
- AllAddresses(): deduplicates primary + fallback addresses

Config example:
  [[nodes]]
  name = "rift"
  address = "rift.scylla-hammerhead.ts.net:9444"
  addresses = ["100.95.252.120:9444", "192.168.88.181:9444"]

Existing configs without addresses[] work unchanged.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

cmd/mcp/dial.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"os"
 	"strings"
+	"time"
 
 	mcpv1 "git.wntrmute.dev/mc/mcp/gen/mcp/v1"
 	"git.wntrmute.dev/mc/mcp/internal/config"
@@ -52,6 +53,38 @@ func dialAgent(address string, cfg *config.CLIConfig) (mcpv1.McpAgentServiceClie
 	return mcpv1.NewMcpAgentServiceClient(conn), conn, nil
 }
 
+// dialAgentMulti tries each address in order and returns the first successful
+// connection. Provides resilience when Tailscale DNS is down or a node is
+// reachable via LAN but not Tailnet.
+func dialAgentMulti(addresses []string, cfg *config.CLIConfig) (mcpv1.McpAgentServiceClient, *grpc.ClientConn, error) {
+	if len(addresses) == 0 {
+		return nil, nil, fmt.Errorf("no addresses to dial")
+	}
+	if len(addresses) == 1 {
+		return dialAgent(addresses[0], cfg)
+	}
+
+	var lastErr error
+	for _, addr := range addresses {
+		client, conn, err := dialAgent(addr, cfg)
+		if err != nil {
+			lastErr = fmt.Errorf("%s: %w", addr, err)
+			continue
+		}
+		// Quick health check to verify the connection actually works.
+		ctx, cancel := context.WithTimeout(context.Background(), 3*time.Second)
+		_, err = client.NodeStatus(ctx, &mcpv1.NodeStatusRequest{})
+		cancel()
+		if err != nil {
+			_ = conn.Close()
+			lastErr = fmt.Errorf("%s: %w", addr, err)
+			continue
+		}
+		return client, conn, nil
+	}
+	return nil, nil, fmt.Errorf("all addresses failed, last error: %w", lastErr)
+}
+
 // dialMaster connects to the master at the given address and returns a gRPC
 // client for the McpMasterService.
 func dialMaster(address string, cfg *config.CLIConfig) (mcpv1.McpMasterServiceClient, *grpc.ClientConn, error) {

cmd/mcp/helpers.go

@@ -9,7 +9,7 @@ import (
 )
 
 // findNodeAddress looks up a node by name in the CLI config and returns
-// its address.
+// its primary address.
 func findNodeAddress(cfg *config.CLIConfig, nodeName string) (string, error) {
 	for _, n := range cfg.Nodes {
 		if n.Name == nodeName {
@@ -19,6 +19,16 @@ func findNodeAddress(cfg *config.CLIConfig, nodeName string) (string, error) {
 	return "", fmt.Errorf("node %q not found in config", nodeName)
 }
 
+// findNode looks up a node by name in the CLI config.
+func findNode(cfg *config.CLIConfig, nodeName string) (*config.NodeConfig, error) {
+	for i := range cfg.Nodes {
+		if cfg.Nodes[i].Name == nodeName {
+			return &cfg.Nodes[i], nil
+		}
+	}
+	return nil, fmt.Errorf("node %q not found in config", nodeName)
+}
+
 // printComponentResults prints the result of each component operation.
 func printComponentResults(results []*mcpv1.ComponentResult) {
 	for _, r := range results {

cmd/mcp/status.go

@@ -27,7 +27,7 @@ func forEachNode(fn func(node config.NodeConfig, client mcpv1.McpAgentServiceCli
 	}
 
 	for _, node := range cfg.Nodes {
-		client, conn, err := dialAgent(node.Address, cfg)
+		client, conn, err := dialAgentMulti(node.AllAddresses(), cfg)
 		if err != nil {
 			_, _ = fmt.Fprintf(os.Stderr, "warning: %s: %v\n", node.Name, err)
 			continue
@@ -85,7 +85,7 @@ func psCmd() *cobra.Command {
 		Short: "Live check: query runtime on all agents",
 		RunE: func(cmd *cobra.Command, args []string) error {
 			w := newTable()
-			_, _ = fmt.Fprintln(w, "SERVICE\tCOMPONENT\tNODE\tSTATE\tVERSION\tUPTIME")
+			_, _ = fmt.Fprintln(w, "SERVICE\tCOMPONENT\tNODE\tSTATE\tVERSION\tUPTIME\t")
 
 			now := time.Now()
 			if err := forEachNode(func(node config.NodeConfig, client mcpv1.McpAgentServiceClient) error {
@@ -96,19 +96,25 @@ func psCmd() *cobra.Command {
 				}
 
 				for _, svc := range resp.GetServices() {
+					comment := svc.GetComment()
 					for _, comp := range svc.GetComponents() {
 						uptime := "-"
 						if comp.GetStarted() != nil {
 							d := now.Sub(comp.GetStarted().AsTime())
 							uptime = formatDuration(d)
 						}
-						_, _ = fmt.Fprintf(w, "%s\t%s\t%s\t%s\t%s\t%s\n",
+						col7 := ""
+						if comment != "" {
+							col7 = "# " + comment
+						}
+						_, _ = fmt.Fprintf(w, "%s\t%s\t%s\t%s\t%s\t%s\t%s\n",
 							svc.GetName(),
 							comp.GetName(),
 							node.Name,
 							comp.GetObservedState(),
 							comp.GetVersion(),
 							uptime,
+							col7,
 						)
 					}
 				}