Fix EnsureRecord to check all existing records before updating

When multiple A records exist for a service (e.g., LAN and Tailscale
IPs), check all of them for the correct value before attempting an
update. Previously only checked the first record, which could trigger
a 409 conflict if another record already had the target value.

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

.golangci.yaml

@@ -5,6 +5,24 @@ run:
   tests: true
 
 linters:
+  exclusions:
+    paths:
+      - vendor
+    rules:
+      # In test files, suppress gosec rules that are false positives:
+      # G101: hardcoded test credentials
+      # G304: file paths from variables (t.TempDir paths)
+      # G306: WriteFile with 0644 (cert files need to be readable)
+      # G404: weak RNG (not security-relevant in tests)
+      - path: "_test\\.go"
+        linters:
+          - gosec
+        text: "G101|G304|G306|G404"
+      # Nil context is acceptable in tests for nil-receiver safety checks.
+      - path: "_test\\.go"
+        linters:
+          - staticcheck
+        text: "SA1012"
   default: none
   enable:
     - errcheck
@@ -69,12 +87,3 @@ formatters:
 issues:
   max-issues-per-linter: 0
   max-same-issues: 0
-
-  exclusions:
-    paths:
-      - vendor
-    rules:
-      - path: "_test\\.go"
-        linters:
-          - gosec
-        text: "G101"

flake.nix

@@ -10,7 +10,7 @@
     let
       system = "x86_64-linux";
       pkgs = nixpkgs.legacyPackages.${system};
-      version = "0.1.0";
+      version = "0.5.0";
     in
     {
       packages.${system} = {

gen/mcp/v1/mcp.pb.go

@@ -2294,7 +2294,7 @@ const file_proto_mcp_v1_mcp_proto_rawDesc = "" +
 	"\bPushFile\x12\x17.mcp.v1.PushFileRequest\x1a\x18.mcp.v1.PushFileResponse\x12=\n" +
 	"\bPullFile\x12\x17.mcp.v1.PullFileRequest\x1a\x18.mcp.v1.PullFileResponse\x12C\n" +
 	"\n" +
-	"NodeStatus\x12\x19.mcp.v1.NodeStatusRequest\x1a\x1a.mcp.v1.NodeStatusResponseB,Z*git.wntrmute.dev/mc/mcp/gen/mcp/v1;mcpv1b\x06proto3"
+	"NodeStatus\x12\x19.mcp.v1.NodeStatusRequest\x1a\x1a.mcp.v1.NodeStatusResponseB*Z(git.wntrmute.dev/mc/mcp/gen/mcp/v1;mcpv1b\x06proto3"
 
 var (
 	file_proto_mcp_v1_mcp_proto_rawDescOnce sync.Once

go.mod

@@ -3,7 +3,7 @@ module git.wntrmute.dev/mc/mcp
 go 1.25.7
 
 require (
-	git.wntrmute.dev/mc/mc-proxy v1.1.0
+	git.wntrmute.dev/mc/mc-proxy v1.2.0
 	github.com/pelletier/go-toml/v2 v2.3.0
 	github.com/spf13/cobra v1.10.2
 	golang.org/x/sys v0.42.0

go.sum

@@ -1,5 +1,5 @@
-git.wntrmute.dev/mc/mc-proxy v1.1.0 h1:r8LnBuiS0OqLSuHMuRikQlIhmeNtlJV9IrIvVVTIGuw=
-git.wntrmute.dev/mc/mc-proxy v1.1.0/go.mod h1:6w8smZ/DNJVBb4n5std/faye0ROLEXfk3iJY1XNc1JU=
+git.wntrmute.dev/mc/mc-proxy v1.2.0 h1:TVfwdZzYqMs/ksZ0a6aSR7hKGDDMG8X0Od5RIxlbXKQ=
+git.wntrmute.dev/mc/mc-proxy v1.2.0/go.mod h1:6w8smZ/DNJVBb4n5std/faye0ROLEXfk3iJY1XNc1JU=
 git.wntrmute.dev/mc/mcdsl v1.2.0 h1:41hep7/PNZJfN0SN/nM+rQpyF1GSZcvNNjyVG81DI7U=
 git.wntrmute.dev/mc/mcdsl v1.2.0/go.mod h1:lXYrAt74ZUix6rx9oVN8d2zH1YJoyp4uxPVKQ+SSxuM=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=

internal/agent/agent.go

@@ -33,6 +33,8 @@ type Agent struct {
 	Logger    *slog.Logger
 	PortAlloc *PortAllocator
 	Proxy     *ProxyRouter
+	Certs     *CertProvisioner
+	DNS       *DNSRegistrar
 }
 
 // Run starts the agent: opens the database, sets up the gRPC server with
@@ -57,6 +59,16 @@ func Run(cfg *config.AgentConfig) error {
 		return fmt.Errorf("connect to mc-proxy: %w", err)
 	}
 
+	certs, err := NewCertProvisioner(cfg.Metacrypt, cfg.MCProxy.CertDir, logger)
+	if err != nil {
+		return fmt.Errorf("create cert provisioner: %w", err)
+	}
+
+	dns, err := NewDNSRegistrar(cfg.MCNS, logger)
+	if err != nil {
+		return fmt.Errorf("create DNS registrar: %w", err)
+	}
+
 	a := &Agent{
 		Config:    cfg,
 		DB:        db,
@@ -65,6 +77,8 @@ func Run(cfg *config.AgentConfig) error {
 		Logger:    logger,
 		PortAlloc: NewPortAllocator(),
 		Proxy:     proxy,
+		Certs:     certs,
+		DNS:       dns,
 	}
 
 	tlsCert, err := tls.LoadX509KeyPair(cfg.Server.TLSCert, cfg.Server.TLSKey)

internal/agent/certs.go

@@ -0,0 +1,244 @@
+package agent
+
+import (
+	"bytes"
+	"context"
+	"crypto/tls"
+	"crypto/x509"
+	"encoding/json"
+	"encoding/pem"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+
+	"git.wntrmute.dev/mc/mcp/internal/auth"
+	"git.wntrmute.dev/mc/mcp/internal/config"
+)
+
+// renewWindow is how far before expiry a cert is considered stale and
+// should be re-issued.
+const renewWindow = 30 * 24 * time.Hour // 30 days
+
+// CertProvisioner requests TLS certificates from Metacrypt's CA API
+// and writes them to the mc-proxy cert directory. It is nil-safe: all
+// methods are no-ops when the receiver is nil.
+type CertProvisioner struct {
+	serverURL  string
+	token      string
+	mount      string
+	issuer     string
+	certDir    string
+	httpClient *http.Client
+	logger     *slog.Logger
+}
+
+// NewCertProvisioner creates a CertProvisioner. Returns (nil, nil) if
+// cfg.ServerURL is empty (cert provisioning disabled).
+func NewCertProvisioner(cfg config.MetacryptConfig, certDir string, logger *slog.Logger) (*CertProvisioner, error) {
+	if cfg.ServerURL == "" {
+		logger.Info("metacrypt not configured, cert provisioning disabled")
+		return nil, nil
+	}
+
+	token, err := auth.LoadToken(cfg.TokenPath)
+	if err != nil {
+		return nil, fmt.Errorf("load metacrypt token: %w", err)
+	}
+
+	httpClient, err := newTLSClient(cfg.CACert)
+	if err != nil {
+		return nil, fmt.Errorf("create metacrypt HTTP client: %w", err)
+	}
+
+	logger.Info("metacrypt cert provisioner enabled", "server", cfg.ServerURL, "mount", cfg.Mount, "issuer", cfg.Issuer)
+	return &CertProvisioner{
+		serverURL:  strings.TrimRight(cfg.ServerURL, "/"),
+		token:      token,
+		mount:      cfg.Mount,
+		issuer:     cfg.Issuer,
+		certDir:    certDir,
+		httpClient: httpClient,
+		logger:     logger,
+	}, nil
+}
+
+// EnsureCert checks whether a valid TLS certificate exists for the
+// service. If the cert is missing or near expiry, it requests a new
+// one from Metacrypt.
+func (p *CertProvisioner) EnsureCert(ctx context.Context, serviceName string, hostnames []string) error {
+	if p == nil || len(hostnames) == 0 {
+		return nil
+	}
+
+	certPath := filepath.Join(p.certDir, serviceName+".pem")
+
+	if remaining, ok := certTimeRemaining(certPath); ok {
+		if remaining > renewWindow {
+			p.logger.Debug("cert valid, skipping provisioning",
+				"service", serviceName,
+				"expires_in", remaining.Round(time.Hour),
+			)
+			return nil
+		}
+		p.logger.Info("cert near expiry, re-issuing",
+			"service", serviceName,
+			"expires_in", remaining.Round(time.Hour),
+		)
+	}
+
+	return p.issueCert(ctx, serviceName, hostnames[0], hostnames)
+}
+
+// issueCert calls Metacrypt's CA API to issue a certificate and writes
+// the chain and key to the cert directory.
+func (p *CertProvisioner) issueCert(ctx context.Context, serviceName, commonName string, dnsNames []string) error {
+	p.logger.Info("provisioning TLS cert",
+		"service", serviceName,
+		"cn", commonName,
+		"sans", dnsNames,
+	)
+
+	reqBody := map[string]interface{}{
+		"mount":     p.mount,
+		"operation": "issue",
+		"data": map[string]interface{}{
+			"issuer":      p.issuer,
+			"common_name": commonName,
+			"dns_names":   dnsNames,
+			"profile":     "server",
+			"ttl":         "2160h",
+		},
+	}
+
+	body, err := json.Marshal(reqBody)
+	if err != nil {
+		return fmt.Errorf("marshal issue request: %w", err)
+	}
+
+	url := p.serverURL + "/v1/engine/request"
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
+	if err != nil {
+		return fmt.Errorf("create issue request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", "Bearer "+p.token)
+
+	resp, err := p.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("issue cert: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	respBody, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("read issue response: %w", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("issue cert: metacrypt returned %d: %s", resp.StatusCode, string(respBody))
+	}
+
+	var result struct {
+		ChainPEM  string `json:"chain_pem"`
+		KeyPEM    string `json:"key_pem"`
+		Serial    string `json:"serial"`
+		ExpiresAt string `json:"expires_at"`
+	}
+	if err := json.Unmarshal(respBody, &result); err != nil {
+		return fmt.Errorf("parse issue response: %w", err)
+	}
+
+	if result.ChainPEM == "" || result.KeyPEM == "" {
+		return fmt.Errorf("issue cert: response missing chain_pem or key_pem")
+	}
+
+	// Write cert and key atomically (temp file + rename).
+	certPath := filepath.Join(p.certDir, serviceName+".pem")
+	keyPath := filepath.Join(p.certDir, serviceName+".key")
+
+	if err := atomicWrite(certPath, []byte(result.ChainPEM), 0644); err != nil {
+		return fmt.Errorf("write cert: %w", err)
+	}
+	if err := atomicWrite(keyPath, []byte(result.KeyPEM), 0600); err != nil {
+		return fmt.Errorf("write key: %w", err)
+	}
+
+	p.logger.Info("cert provisioned",
+		"service", serviceName,
+		"serial", result.Serial,
+		"expires_at", result.ExpiresAt,
+	)
+	return nil
+}
+
+// certTimeRemaining returns the time until the leaf certificate at
+// path expires. Returns (0, false) if the cert cannot be read or parsed.
+func certTimeRemaining(path string) (time.Duration, bool) {
+	data, err := os.ReadFile(path) //nolint:gosec // path from trusted config
+	if err != nil {
+		return 0, false
+	}
+
+	block, _ := pem.Decode(data)
+	if block == nil {
+		return 0, false
+	}
+
+	cert, err := x509.ParseCertificate(block.Bytes)
+	if err != nil {
+		return 0, false
+	}
+
+	remaining := time.Until(cert.NotAfter)
+	if remaining <= 0 {
+		return 0, true // expired
+	}
+	return remaining, true
+}
+
+// atomicWrite writes data to a temporary file then renames it to path,
+// ensuring readers never see a partial file.
+func atomicWrite(path string, data []byte, perm os.FileMode) error {
+	tmp := path + ".tmp"
+	if err := os.WriteFile(tmp, data, perm); err != nil {
+		return fmt.Errorf("write %s: %w", tmp, err)
+	}
+	if err := os.Rename(tmp, path); err != nil {
+		_ = os.Remove(tmp)
+		return fmt.Errorf("rename %s -> %s: %w", tmp, path, err)
+	}
+	return nil
+}
+
+// newTLSClient creates an HTTP client with TLS 1.3 minimum. If
+// caCertPath is non-empty, the CA certificate is loaded into the
+// root CA pool.
+func newTLSClient(caCertPath string) (*http.Client, error) {
+	tlsConfig := &tls.Config{
+		MinVersion: tls.VersionTLS13,
+	}
+
+	if caCertPath != "" {
+		caCert, err := os.ReadFile(caCertPath) //nolint:gosec // path from trusted config
+		if err != nil {
+			return nil, fmt.Errorf("read CA cert %q: %w", caCertPath, err)
+		}
+		pool := x509.NewCertPool()
+		if !pool.AppendCertsFromPEM(caCert) {
+			return nil, fmt.Errorf("parse CA cert %q: no valid certificates found", caCertPath)
+		}
+		tlsConfig.RootCAs = pool
+	}
+
+	return &http.Client{
+		Timeout: 30 * time.Second,
+		Transport: &http.Transport{
+			TLSClientConfig: tlsConfig,
+		},
+	}, nil
+}

internal/agent/certs_test.go

@@ -0,0 +1,392 @@
+package agent
+
+import (
+	"context"
+	"crypto/ecdsa"
+	"crypto/elliptic"
+	"crypto/rand"
+	"crypto/x509"
+	"crypto/x509/pkix"
+	"encoding/json"
+	"encoding/pem"
+	"log/slog"
+	"math/big"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"path/filepath"
+	"testing"
+	"time"
+
+	"git.wntrmute.dev/mc/mcp/internal/config"
+	"git.wntrmute.dev/mc/mcp/internal/registry"
+)
+
+func TestNilCertProvisionerIsNoop(t *testing.T) {
+	var p *CertProvisioner
+	if err := p.EnsureCert(context.Background(), "svc", []string{"svc.example.com"}); err != nil {
+		t.Fatalf("EnsureCert on nil: %v", err)
+	}
+}
+
+func TestNewCertProvisionerDisabledWhenUnconfigured(t *testing.T) {
+	p, err := NewCertProvisioner(config.MetacryptConfig{}, "/tmp", slog.Default())
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if p != nil {
+		t.Fatal("expected nil provisioner for empty config")
+	}
+}
+
+func TestEnsureCertSkipsValidCert(t *testing.T) {
+	certDir := t.TempDir()
+	certPath := filepath.Join(certDir, "svc.pem")
+	keyPath := filepath.Join(certDir, "svc.key")
+
+	// Generate a cert that expires in 90 days.
+	writeSelfSignedCert(t, certPath, keyPath, "svc.example.com", 90*24*time.Hour)
+
+	// Create a provisioner that would fail if it tried to issue.
+	p := &CertProvisioner{
+		serverURL: "https://will-fail-if-called:9999",
+		certDir:   certDir,
+		logger:    slog.Default(),
+	}
+
+	if err := p.EnsureCert(context.Background(), "svc", []string{"svc.example.com"}); err != nil {
+		t.Fatalf("EnsureCert: %v", err)
+	}
+}
+
+func TestEnsureCertReissuesExpiring(t *testing.T) {
+	certDir := t.TempDir()
+	certPath := filepath.Join(certDir, "svc.pem")
+	keyPath := filepath.Join(certDir, "svc.key")
+
+	// Generate a cert that expires in 10 days (within 30-day renewal window).
+	writeSelfSignedCert(t, certPath, keyPath, "svc.example.com", 10*24*time.Hour)
+
+	// Mock Metacrypt API.
+	newCert, newKey := generateCertPEM(t, "svc.example.com", 90*24*time.Hour)
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		resp := map[string]string{
+			"chain_pem":  newCert,
+			"key_pem":    newKey,
+			"serial":     "abc123",
+			"expires_at": time.Now().Add(90 * 24 * time.Hour).Format(time.RFC3339),
+		}
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(resp)
+	}))
+	defer srv.Close()
+
+	p := &CertProvisioner{
+		serverURL:  srv.URL,
+		token:      "test-token",
+		mount:      "pki",
+		issuer:     "infra",
+		certDir:    certDir,
+		httpClient: srv.Client(),
+		logger:     slog.Default(),
+	}
+
+	if err := p.EnsureCert(context.Background(), "svc", []string{"svc.example.com"}); err != nil {
+		t.Fatalf("EnsureCert: %v", err)
+	}
+
+	// Verify new cert was written.
+	got, err := os.ReadFile(certPath)
+	if err != nil {
+		t.Fatalf("read cert: %v", err)
+	}
+	if string(got) != newCert {
+		t.Fatal("cert file was not updated with new cert")
+	}
+}
+
+func TestIssueCertWritesFiles(t *testing.T) {
+	certDir := t.TempDir()
+
+	// Mock Metacrypt API.
+	certPEM, keyPEM := generateCertPEM(t, "svc.example.com", 90*24*time.Hour)
+	var gotAuth string
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		gotAuth = r.Header.Get("Authorization")
+
+		var req map[string]interface{}
+		if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+			http.Error(w, "bad request", http.StatusBadRequest)
+			return
+		}
+
+		// Verify request structure.
+		if req["mount"] != "pki" || req["operation"] != "issue" {
+			t.Errorf("unexpected request: %v", req)
+		}
+
+		resp := map[string]string{
+			"chain_pem":  certPEM,
+			"key_pem":    keyPEM,
+			"serial":     "deadbeef",
+			"expires_at": time.Now().Add(90 * 24 * time.Hour).Format(time.RFC3339),
+		}
+		w.Header().Set("Content-Type", "application/json")
+		_ = json.NewEncoder(w).Encode(resp)
+	}))
+	defer srv.Close()
+
+	p := &CertProvisioner{
+		serverURL:  srv.URL,
+		token:      "my-service-token",
+		mount:      "pki",
+		issuer:     "infra",
+		certDir:    certDir,
+		httpClient: srv.Client(),
+		logger:     slog.Default(),
+	}
+
+	if err := p.EnsureCert(context.Background(), "svc", []string{"svc.example.com"}); err != nil {
+		t.Fatalf("EnsureCert: %v", err)
+	}
+
+	// Verify auth header.
+	if gotAuth != "Bearer my-service-token" {
+		t.Fatalf("auth header: got %q, want %q", gotAuth, "Bearer my-service-token")
+	}
+
+	// Verify cert file.
+	certData, err := os.ReadFile(filepath.Join(certDir, "svc.pem"))
+	if err != nil {
+		t.Fatalf("read cert: %v", err)
+	}
+	if string(certData) != certPEM {
+		t.Fatal("cert content mismatch")
+	}
+
+	// Verify key file.
+	keyData, err := os.ReadFile(filepath.Join(certDir, "svc.key"))
+	if err != nil {
+		t.Fatalf("read key: %v", err)
+	}
+	if string(keyData) != keyPEM {
+		t.Fatal("key content mismatch")
+	}
+
+	// Verify key file permissions.
+	info, err := os.Stat(filepath.Join(certDir, "svc.key"))
+	if err != nil {
+		t.Fatalf("stat key: %v", err)
+	}
+	if perm := info.Mode().Perm(); perm != 0600 {
+		t.Fatalf("key permissions: got %o, want 0600", perm)
+	}
+}
+
+func TestIssueCertAPIError(t *testing.T) {
+	certDir := t.TempDir()
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		http.Error(w, `{"error":"sealed"}`, http.StatusServiceUnavailable)
+	}))
+	defer srv.Close()
+
+	p := &CertProvisioner{
+		serverURL:  srv.URL,
+		token:      "test-token",
+		mount:      "pki",
+		issuer:     "infra",
+		certDir:    certDir,
+		httpClient: srv.Client(),
+		logger:     slog.Default(),
+	}
+
+	err := p.EnsureCert(context.Background(), "svc", []string{"svc.example.com"})
+	if err == nil {
+		t.Fatal("expected error for sealed metacrypt")
+	}
+}
+
+func TestCertTimeRemaining(t *testing.T) {
+	t.Run("missing file", func(t *testing.T) {
+		if _, ok := certTimeRemaining("/nonexistent/cert.pem"); ok {
+			t.Fatal("expected false for missing file")
+		}
+	})
+
+	t.Run("valid cert", func(t *testing.T) {
+		certDir := t.TempDir()
+		path := filepath.Join(certDir, "test.pem")
+		writeSelfSignedCert(t, path, filepath.Join(certDir, "test.key"), "test.example.com", 90*24*time.Hour)
+
+		remaining, ok := certTimeRemaining(path)
+		if !ok {
+			t.Fatal("expected true for valid cert")
+		}
+		// Should be close to 90 days.
+		if remaining < 89*24*time.Hour || remaining > 91*24*time.Hour {
+			t.Fatalf("remaining: got %v, want ~90 days", remaining)
+		}
+	})
+
+	t.Run("expired cert", func(t *testing.T) {
+		certDir := t.TempDir()
+		path := filepath.Join(certDir, "expired.pem")
+		// Write a cert that's already expired (valid from -2h to -1h).
+		writeExpiredCert(t, path, filepath.Join(certDir, "expired.key"), "expired.example.com")
+
+		remaining, ok := certTimeRemaining(path)
+		if !ok {
+			t.Fatal("expected true for expired cert")
+		}
+		if remaining > 0 {
+			t.Fatalf("remaining: got %v, want <= 0", remaining)
+		}
+	})
+}
+
+func TestHasL7Routes(t *testing.T) {
+	tests := []struct {
+		name   string
+		routes []registry.Route
+		want   bool
+	}{
+		{"nil", nil, false},
+		{"empty", []registry.Route{}, false},
+		{"l4 only", []registry.Route{{Mode: "l4"}}, false},
+		{"l7 only", []registry.Route{{Mode: "l7"}}, true},
+		{"mixed", []registry.Route{{Mode: "l4"}, {Mode: "l7"}}, true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := hasL7Routes(tt.routes); got != tt.want {
+				t.Fatalf("hasL7Routes = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestL7Hostnames(t *testing.T) {
+	routes := []registry.Route{
+		{Mode: "l7", Hostname: ""},
+		{Mode: "l4", Hostname: "ignored.example.com"},
+		{Mode: "l7", Hostname: "custom.example.com"},
+		{Mode: "l7", Hostname: ""}, // duplicate default
+	}
+
+	got := l7Hostnames("myservice", routes)
+	want := []string{"myservice.svc.mcp.metacircular.net", "custom.example.com"}
+
+	if len(got) != len(want) {
+		t.Fatalf("got %v, want %v", got, want)
+	}
+	for i := range want {
+		if got[i] != want[i] {
+			t.Fatalf("got[%d] = %q, want %q", i, got[i], want[i])
+		}
+	}
+}
+
+func TestAtomicWrite(t *testing.T) {
+	dir := t.TempDir()
+	path := filepath.Join(dir, "test.txt")
+
+	if err := atomicWrite(path, []byte("hello"), 0644); err != nil {
+		t.Fatalf("atomicWrite: %v", err)
+	}
+
+	data, err := os.ReadFile(path)
+	if err != nil {
+		t.Fatalf("read: %v", err)
+	}
+	if string(data) != "hello" {
+		t.Fatalf("got %q, want %q", string(data), "hello")
+	}
+
+	// Verify no .tmp file left behind.
+	if _, err := os.Stat(path + ".tmp"); !os.IsNotExist(err) {
+		t.Fatal("temp file should not exist after atomic write")
+	}
+}
+
+// --- test helpers ---
+
+// writeSelfSignedCert generates a self-signed cert/key and writes them to disk.
+func writeSelfSignedCert(t *testing.T, certPath, keyPath, hostname string, validity time.Duration) {
+	t.Helper()
+	certPEM, keyPEM := generateCertPEM(t, hostname, validity)
+	if err := os.WriteFile(certPath, []byte(certPEM), 0644); err != nil {
+		t.Fatalf("write cert: %v", err)
+	}
+	if err := os.WriteFile(keyPath, []byte(keyPEM), 0600); err != nil {
+		t.Fatalf("write key: %v", err)
+	}
+}
+
+// writeExpiredCert generates a cert that is already expired.
+func writeExpiredCert(t *testing.T, certPath, keyPath, hostname string) {
+	t.Helper()
+	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		t.Fatalf("generate key: %v", err)
+	}
+
+	tmpl := &x509.Certificate{
+		SerialNumber: big.NewInt(1),
+		Subject:      pkix.Name{CommonName: hostname},
+		DNSNames:     []string{hostname},
+		NotBefore:    time.Now().Add(-2 * time.Hour),
+		NotAfter:     time.Now().Add(-1 * time.Hour),
+	}
+
+	der, err := x509.CreateCertificate(rand.Reader, tmpl, tmpl, &key.PublicKey, key)
+	if err != nil {
+		t.Fatalf("create cert: %v", err)
+	}
+
+	certPEM := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der})
+	keyDER, err := x509.MarshalECPrivateKey(key)
+	if err != nil {
+		t.Fatalf("marshal key: %v", err)
+	}
+	keyPEM := pem.EncodeToMemory(&pem.Block{Type: "EC PRIVATE KEY", Bytes: keyDER})
+
+	if err := os.WriteFile(certPath, certPEM, 0644); err != nil {
+		t.Fatalf("write cert: %v", err)
+	}
+	if err := os.WriteFile(keyPath, keyPEM, 0600); err != nil {
+		t.Fatalf("write key: %v", err)
+	}
+}
+
+// generateCertPEM generates a self-signed cert and returns PEM strings.
+func generateCertPEM(t *testing.T, hostname string, validity time.Duration) (certPEM, keyPEM string) {
+	t.Helper()
+	key, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+	if err != nil {
+		t.Fatalf("generate key: %v", err)
+	}
+
+	tmpl := &x509.Certificate{
+		SerialNumber: big.NewInt(1),
+		Subject:      pkix.Name{CommonName: hostname},
+		DNSNames:     []string{hostname},
+		NotBefore:    time.Now().Add(-1 * time.Hour),
+		NotAfter:     time.Now().Add(validity),
+	}
+
+	der, err := x509.CreateCertificate(rand.Reader, tmpl, tmpl, &key.PublicKey, key)
+	if err != nil {
+		t.Fatalf("create cert: %v", err)
+	}
+
+	certBlock := pem.EncodeToMemory(&pem.Block{Type: "CERTIFICATE", Bytes: der})
+	keyDER, err := x509.MarshalECPrivateKey(key)
+	if err != nil {
+		t.Fatalf("marshal key: %v", err)
+	}
+	keyBlock := pem.EncodeToMemory(&pem.Block{Type: "EC PRIVATE KEY", Bytes: keyDER})
+
+	return string(certBlock), string(keyBlock)
+}

internal/agent/deploy.go

@@ -146,6 +146,14 @@ func (a *Agent) deployComponent(ctx context.Context, serviceName string, cs *mcp
 		}
 	}
 
+	// Provision TLS certs for L7 routes before registering with mc-proxy.
+	if a.Certs != nil && hasL7Routes(regRoutes) {
+		hostnames := l7Hostnames(serviceName, regRoutes)
+		if err := a.Certs.EnsureCert(ctx, serviceName, hostnames); err != nil {
+			a.Logger.Warn("failed to provision TLS cert", "service", serviceName, "err", err)
+		}
+	}
+
 	// Register routes with mc-proxy after the container is running.
 	if len(regRoutes) > 0 && a.Proxy != nil {
 		hostPorts, err := registry.GetRouteHostPorts(a.DB, serviceName, compName)
@@ -156,6 +164,13 @@ func (a *Agent) deployComponent(ctx context.Context, serviceName string, cs *mcp
 		}
 	}
 
+	// Register DNS record for the service.
+	if a.DNS != nil && len(regRoutes) > 0 {
+		if err := a.DNS.EnsureRecord(ctx, serviceName); err != nil {
+			a.Logger.Warn("failed to register DNS record", "service", serviceName, "err", err)
+		}
+	}
+
 	if err := registry.UpdateComponentState(a.DB, serviceName, compName, "running", "running"); err != nil {
 		a.Logger.Warn("failed to update component state", "service", serviceName, "component", compName, "err", err)
 	}
@@ -209,6 +224,37 @@ func ensureService(db *sql.DB, name string, active bool) error {
 	return registry.UpdateServiceActive(db, name, active)
 }
 
+// hasL7Routes reports whether any route uses L7 (TLS-terminating) mode.
+func hasL7Routes(routes []registry.Route) bool {
+	for _, r := range routes {
+		if r.Mode == "l7" {
+			return true
+		}
+	}
+	return false
+}
+
+// l7Hostnames returns the unique hostnames from L7 routes, applying
+// the default hostname convention when a route has no explicit hostname.
+func l7Hostnames(serviceName string, routes []registry.Route) []string {
+	seen := make(map[string]bool)
+	var hostnames []string
+	for _, r := range routes {
+		if r.Mode != "l7" {
+			continue
+		}
+		h := r.Hostname
+		if h == "" {
+			h = serviceName + ".svc.mcp.metacircular.net"
+		}
+		if !seen[h] {
+			seen[h] = true
+			hostnames = append(hostnames, h)
+		}
+	}
+	return hostnames
+}
+
 // ensureComponent creates the component if it does not exist, or updates its
 // spec if it does.
 func ensureComponent(db *sql.DB, c *registry.Component) error {

internal/agent/dns.go

@@ -0,0 +1,265 @@
+package agent
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"strings"
+
+	"git.wntrmute.dev/mc/mcp/internal/auth"
+	"git.wntrmute.dev/mc/mcp/internal/config"
+)
+
+// DNSRegistrar creates and removes A records in MCNS during deploy
+// and stop. It is nil-safe: all methods are no-ops when the receiver
+// is nil.
+type DNSRegistrar struct {
+	serverURL  string
+	token      string
+	zone       string
+	nodeAddr   string
+	httpClient *http.Client
+	logger     *slog.Logger
+}
+
+// dnsRecord is the JSON representation of an MCNS record.
+type dnsRecord struct {
+	ID    int    `json:"ID"`
+	Name  string `json:"Name"`
+	Type  string `json:"Type"`
+	Value string `json:"Value"`
+	TTL   int    `json:"TTL"`
+}
+
+// NewDNSRegistrar creates a DNSRegistrar. Returns (nil, nil) if
+// cfg.ServerURL is empty (DNS registration disabled).
+func NewDNSRegistrar(cfg config.MCNSConfig, logger *slog.Logger) (*DNSRegistrar, error) {
+	if cfg.ServerURL == "" {
+		logger.Info("mcns not configured, DNS registration disabled")
+		return nil, nil
+	}
+
+	token, err := auth.LoadToken(cfg.TokenPath)
+	if err != nil {
+		return nil, fmt.Errorf("load mcns token: %w", err)
+	}
+
+	httpClient, err := newTLSClient(cfg.CACert)
+	if err != nil {
+		return nil, fmt.Errorf("create mcns HTTP client: %w", err)
+	}
+
+	logger.Info("mcns DNS registrar enabled", "server", cfg.ServerURL, "zone", cfg.Zone, "node_addr", cfg.NodeAddr)
+	return &DNSRegistrar{
+		serverURL:  strings.TrimRight(cfg.ServerURL, "/"),
+		token:      token,
+		zone:       cfg.Zone,
+		nodeAddr:   cfg.NodeAddr,
+		httpClient: httpClient,
+		logger:     logger,
+	}, nil
+}
+
+// EnsureRecord ensures an A record exists for the service in the
+// configured zone, pointing to the node's address.
+func (d *DNSRegistrar) EnsureRecord(ctx context.Context, serviceName string) error {
+	if d == nil {
+		return nil
+	}
+
+	existing, err := d.listRecords(ctx, serviceName)
+	if err != nil {
+		return fmt.Errorf("list DNS records: %w", err)
+	}
+
+	// Check if any existing record already has the correct value.
+	for _, r := range existing {
+		if r.Value == d.nodeAddr {
+			d.logger.Debug("DNS record exists, skipping",
+				"service", serviceName,
+				"record", r.Name+"."+d.zone,
+				"value", r.Value,
+			)
+			return nil
+		}
+	}
+
+	// No record with the correct value — update the first one if it exists.
+	if len(existing) > 0 {
+		d.logger.Info("updating DNS record",
+			"service", serviceName,
+			"old_value", existing[0].Value,
+			"new_value", d.nodeAddr,
+		)
+		return d.updateRecord(ctx, existing[0].ID, serviceName)
+	}
+
+	// No existing record — create one.
+	d.logger.Info("creating DNS record",
+		"service", serviceName,
+		"record", serviceName+"."+d.zone,
+		"value", d.nodeAddr,
+	)
+	return d.createRecord(ctx, serviceName)
+}
+
+// RemoveRecord removes A records for the service from the configured zone.
+func (d *DNSRegistrar) RemoveRecord(ctx context.Context, serviceName string) error {
+	if d == nil {
+		return nil
+	}
+
+	existing, err := d.listRecords(ctx, serviceName)
+	if err != nil {
+		return fmt.Errorf("list DNS records: %w", err)
+	}
+
+	if len(existing) == 0 {
+		d.logger.Debug("no DNS record to remove", "service", serviceName)
+		return nil
+	}
+
+	for _, r := range existing {
+		d.logger.Info("removing DNS record",
+			"service", serviceName,
+			"record", r.Name+"."+d.zone,
+			"id", r.ID,
+		)
+		if err := d.deleteRecord(ctx, r.ID); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+// listRecords returns A records matching the service name in the zone.
+func (d *DNSRegistrar) listRecords(ctx context.Context, serviceName string) ([]dnsRecord, error) {
+	url := fmt.Sprintf("%s/v1/zones/%s/records?name=%s&type=A", d.serverURL, d.zone, serviceName)
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
+	if err != nil {
+		return nil, fmt.Errorf("create list request: %w", err)
+	}
+	req.Header.Set("Authorization", "Bearer "+d.token)
+
+	resp, err := d.httpClient.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("list records: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	body, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return nil, fmt.Errorf("read list response: %w", err)
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, fmt.Errorf("list records: mcns returned %d: %s", resp.StatusCode, string(body))
+	}
+
+	var envelope struct {
+		Records []dnsRecord `json:"records"`
+	}
+	if err := json.Unmarshal(body, &envelope); err != nil {
+		return nil, fmt.Errorf("parse list response: %w", err)
+	}
+	return envelope.Records, nil
+}
+
+// createRecord creates an A record in the zone.
+func (d *DNSRegistrar) createRecord(ctx context.Context, serviceName string) error {
+	reqBody := map[string]interface{}{
+		"name":  serviceName,
+		"type":  "A",
+		"value": d.nodeAddr,
+		"ttl":   300,
+	}
+
+	body, err := json.Marshal(reqBody)
+	if err != nil {
+		return fmt.Errorf("marshal create request: %w", err)
+	}
+
+	url := fmt.Sprintf("%s/v1/zones/%s/records", d.serverURL, d.zone)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, url, bytes.NewReader(body))
+	if err != nil {
+		return fmt.Errorf("create record request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", "Bearer "+d.token)
+
+	resp, err := d.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("create record: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode != http.StatusCreated && resp.StatusCode != http.StatusOK {
+		respBody, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("create record: mcns returned %d: %s", resp.StatusCode, string(respBody))
+	}
+
+	return nil
+}
+
+// updateRecord updates an existing record's value.
+func (d *DNSRegistrar) updateRecord(ctx context.Context, recordID int, serviceName string) error {
+	reqBody := map[string]interface{}{
+		"name":  serviceName,
+		"type":  "A",
+		"value": d.nodeAddr,
+		"ttl":   300,
+	}
+
+	body, err := json.Marshal(reqBody)
+	if err != nil {
+		return fmt.Errorf("marshal update request: %w", err)
+	}
+
+	url := fmt.Sprintf("%s/v1/zones/%s/records/%d", d.serverURL, d.zone, recordID)
+	req, err := http.NewRequestWithContext(ctx, http.MethodPut, url, bytes.NewReader(body))
+	if err != nil {
+		return fmt.Errorf("create update request: %w", err)
+	}
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("Authorization", "Bearer "+d.token)
+
+	resp, err := d.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("update record: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode != http.StatusOK {
+		respBody, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("update record: mcns returned %d: %s", resp.StatusCode, string(respBody))
+	}
+
+	return nil
+}
+
+// deleteRecord deletes a record by ID.
+func (d *DNSRegistrar) deleteRecord(ctx context.Context, recordID int) error {
+	url := fmt.Sprintf("%s/v1/zones/%s/records/%d", d.serverURL, d.zone, recordID)
+	req, err := http.NewRequestWithContext(ctx, http.MethodDelete, url, nil)
+	if err != nil {
+		return fmt.Errorf("create delete request: %w", err)
+	}
+	req.Header.Set("Authorization", "Bearer "+d.token)
+
+	resp, err := d.httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("delete record: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode != http.StatusNoContent && resp.StatusCode != http.StatusOK {
+		respBody, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("delete record: mcns returned %d: %s", resp.StatusCode, string(respBody))
+	}
+
+	return nil
+}

internal/agent/dns_test.go

@@ -0,0 +1,214 @@
+package agent
+
+import (
+	"context"
+	"encoding/json"
+	"log/slog"
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"git.wntrmute.dev/mc/mcp/internal/config"
+)
+
+func TestNilDNSRegistrarIsNoop(t *testing.T) {
+	var d *DNSRegistrar
+	if err := d.EnsureRecord(context.Background(), "svc"); err != nil {
+		t.Fatalf("EnsureRecord on nil: %v", err)
+	}
+	if err := d.RemoveRecord(context.Background(), "svc"); err != nil {
+		t.Fatalf("RemoveRecord on nil: %v", err)
+	}
+}
+
+func TestNewDNSRegistrarDisabledWhenUnconfigured(t *testing.T) {
+	d, err := NewDNSRegistrar(config.MCNSConfig{}, slog.Default())
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if d != nil {
+		t.Fatal("expected nil registrar for empty config")
+	}
+}
+
+func TestEnsureRecordCreatesWhenMissing(t *testing.T) {
+	var gotMethod, gotPath, gotAuth string
+	var gotBody map[string]interface{}
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == http.MethodGet {
+			// List returns empty — no existing records.
+			w.Header().Set("Content-Type", "application/json")
+			_, _ = w.Write([]byte(`{"records":[]}`))
+			return
+		}
+		gotMethod = r.Method
+		gotPath = r.URL.Path
+		gotAuth = r.Header.Get("Authorization")
+		_ = json.NewDecoder(r.Body).Decode(&gotBody)
+		w.WriteHeader(http.StatusCreated)
+		_, _ = w.Write([]byte(`{"id":1}`))
+	}))
+	defer srv.Close()
+
+	d := &DNSRegistrar{
+		serverURL:  srv.URL,
+		token:      "test-token",
+		zone:       "svc.mcp.metacircular.net",
+		nodeAddr:   "192.168.88.181",
+		httpClient: srv.Client(),
+		logger:     slog.Default(),
+	}
+
+	if err := d.EnsureRecord(context.Background(), "myservice"); err != nil {
+		t.Fatalf("EnsureRecord: %v", err)
+	}
+
+	if gotMethod != http.MethodPost {
+		t.Fatalf("method: got %q, want POST", gotMethod)
+	}
+	if gotPath != "/v1/zones/svc.mcp.metacircular.net/records" {
+		t.Fatalf("path: got %q", gotPath)
+	}
+	if gotAuth != "Bearer test-token" {
+		t.Fatalf("auth: got %q", gotAuth)
+	}
+	if gotBody["name"] != "myservice" {
+		t.Fatalf("name: got %v", gotBody["name"])
+	}
+	if gotBody["type"] != "A" {
+		t.Fatalf("type: got %v", gotBody["type"])
+	}
+	if gotBody["value"] != "192.168.88.181" {
+		t.Fatalf("value: got %v", gotBody["value"])
+	}
+}
+
+func TestEnsureRecordSkipsWhenExists(t *testing.T) {
+	createCalled := false
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == http.MethodGet {
+			// Return an existing record with the correct value.
+			resp := map[string][]dnsRecord{"records": {{ID: 1, Name: "myservice", Type: "A", Value: "192.168.88.181", TTL: 300}}}
+			w.Header().Set("Content-Type", "application/json")
+			_ = json.NewEncoder(w).Encode(resp)
+			return
+		}
+		createCalled = true
+		w.WriteHeader(http.StatusCreated)
+	}))
+	defer srv.Close()
+
+	d := &DNSRegistrar{
+		serverURL:  srv.URL,
+		token:      "test-token",
+		zone:       "svc.mcp.metacircular.net",
+		nodeAddr:   "192.168.88.181",
+		httpClient: srv.Client(),
+		logger:     slog.Default(),
+	}
+
+	if err := d.EnsureRecord(context.Background(), "myservice"); err != nil {
+		t.Fatalf("EnsureRecord: %v", err)
+	}
+	if createCalled {
+		t.Fatal("should not create when record already exists with correct value")
+	}
+}
+
+func TestEnsureRecordUpdatesWrongValue(t *testing.T) {
+	var gotMethod string
+	var gotPath string
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == http.MethodGet {
+			// Return a record with a stale value.
+			resp := map[string][]dnsRecord{"records": {{ID: 42, Name: "myservice", Type: "A", Value: "10.0.0.1", TTL: 300}}}
+			w.Header().Set("Content-Type", "application/json")
+			_ = json.NewEncoder(w).Encode(resp)
+			return
+		}
+		gotMethod = r.Method
+		gotPath = r.URL.Path
+		w.WriteHeader(http.StatusOK)
+	}))
+	defer srv.Close()
+
+	d := &DNSRegistrar{
+		serverURL:  srv.URL,
+		token:      "test-token",
+		zone:       "svc.mcp.metacircular.net",
+		nodeAddr:   "192.168.88.181",
+		httpClient: srv.Client(),
+		logger:     slog.Default(),
+	}
+
+	if err := d.EnsureRecord(context.Background(), "myservice"); err != nil {
+		t.Fatalf("EnsureRecord: %v", err)
+	}
+	if gotMethod != http.MethodPut {
+		t.Fatalf("method: got %q, want PUT", gotMethod)
+	}
+	if gotPath != "/v1/zones/svc.mcp.metacircular.net/records/42" {
+		t.Fatalf("path: got %q", gotPath)
+	}
+}
+
+func TestRemoveRecordDeletes(t *testing.T) {
+	var gotMethod, gotPath string
+
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method == http.MethodGet {
+			resp := map[string][]dnsRecord{"records": {{ID: 7, Name: "myservice", Type: "A", Value: "192.168.88.181", TTL: 300}}}
+			w.Header().Set("Content-Type", "application/json")
+			_ = json.NewEncoder(w).Encode(resp)
+			return
+		}
+		gotMethod = r.Method
+		gotPath = r.URL.Path
+		w.WriteHeader(http.StatusNoContent)
+	}))
+	defer srv.Close()
+
+	d := &DNSRegistrar{
+		serverURL:  srv.URL,
+		token:      "test-token",
+		zone:       "svc.mcp.metacircular.net",
+		nodeAddr:   "192.168.88.181",
+		httpClient: srv.Client(),
+		logger:     slog.Default(),
+	}
+
+	if err := d.RemoveRecord(context.Background(), "myservice"); err != nil {
+		t.Fatalf("RemoveRecord: %v", err)
+	}
+	if gotMethod != http.MethodDelete {
+		t.Fatalf("method: got %q, want DELETE", gotMethod)
+	}
+	if gotPath != "/v1/zones/svc.mcp.metacircular.net/records/7" {
+		t.Fatalf("path: got %q", gotPath)
+	}
+}
+
+func TestRemoveRecordNoopWhenMissing(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		// List returns empty.
+		w.Header().Set("Content-Type", "application/json")
+		_, _ = w.Write([]byte(`{"records":[]}`))
+	}))
+	defer srv.Close()
+
+	d := &DNSRegistrar{
+		serverURL:  srv.URL,
+		token:      "test-token",
+		zone:       "svc.mcp.metacircular.net",
+		nodeAddr:   "192.168.88.181",
+		httpClient: srv.Client(),
+		logger:     slog.Default(),
+	}
+
+	if err := d.RemoveRecord(context.Background(), "myservice"); err != nil {
+		t.Fatalf("RemoveRecord: %v", err)
+	}
+}

internal/agent/lifecycle.go

@@ -37,6 +37,13 @@ func (a *Agent) StopService(ctx context.Context, req *mcpv1.StopServiceRequest)
 			}
 		}
 
+		// Remove DNS record when stopping the service.
+		if len(c.Routes) > 0 && a.DNS != nil {
+			if err := a.DNS.RemoveRecord(ctx, req.GetName()); err != nil {
+				a.Logger.Warn("failed to remove DNS record", "service", req.GetName(), "err", err)
+			}
+		}
+
 		if err := a.Runtime.Stop(ctx, containerName); err != nil {
 			a.Logger.Info("stop container (ignored)", "container", containerName, "error", err)
 		}

internal/agent/portalloc.go

@@ -33,8 +33,8 @@ func (pa *PortAllocator) Allocate() (int, error) {
 	pa.mu.Lock()
 	defer pa.mu.Unlock()
 
-	for i := range maxRetries {
-		port := portRangeMin + rand.IntN(portRangeMax-portRangeMin)
+	for range maxRetries {
+		port := portRangeMin + rand.IntN(portRangeMax-portRangeMin) //nolint:gosec // port selection, not security
 		if pa.allocated[port] {
 			continue
 		}
@@ -45,7 +45,6 @@ func (pa *PortAllocator) Allocate() (int, error) {
 
 		pa.allocated[port] = true
 		return port, nil
-		_ = i
 	}
 
 	return 0, fmt.Errorf("failed to allocate port after %d attempts", maxRetries)

internal/agent/sync.go

@@ -157,6 +157,24 @@ func (a *Agent) reconcileUntracked(ctx context.Context, known map[string]bool) e
 
 // protoToComponent converts a proto ComponentSpec to a registry Component.
 func protoToComponent(service string, cs *mcpv1.ComponentSpec, desiredState string) *registry.Component {
+	var routes []registry.Route
+	for _, r := range cs.GetRoutes() {
+		mode := r.GetMode()
+		if mode == "" {
+			mode = "l4"
+		}
+		name := r.GetName()
+		if name == "" {
+			name = "default"
+		}
+		routes = append(routes, registry.Route{
+			Name:     name,
+			Port:     int(r.GetPort()),
+			Mode:     mode,
+			Hostname: r.GetHostname(),
+		})
+	}
+
 	return &registry.Component{
 		Name:         cs.GetName(),
 		Service:      service,
@@ -167,6 +185,7 @@ func protoToComponent(service string, cs *mcpv1.ComponentSpec, desiredState stri
 		Ports:        cs.GetPorts(),
 		Volumes:      cs.GetVolumes(),
 		Cmd:          cs.GetCmd(),
+		Routes:       routes,
 		DesiredState: desiredState,
 		Version:      runtime.ExtractVersion(cs.GetImage()),
 	}

internal/config/agent.go

@@ -15,10 +15,52 @@ type AgentConfig struct {
 	MCIAS     MCIASConfig     `toml:"mcias"`
 	Agent     AgentSettings   `toml:"agent"`
 	MCProxy   MCProxyConfig   `toml:"mcproxy"`
+	Metacrypt MetacryptConfig `toml:"metacrypt"`
+	MCNS      MCNSConfig      `toml:"mcns"`
 	Monitor   MonitorConfig   `toml:"monitor"`
 	Log       LogConfig       `toml:"log"`
 }
 
+// MetacryptConfig holds the Metacrypt CA integration settings for
+// automated TLS cert provisioning. If ServerURL is empty, cert
+// provisioning is disabled.
+type MetacryptConfig struct {
+	// ServerURL is the Metacrypt API base URL (e.g. "https://metacrypt:8443").
+	ServerURL string `toml:"server_url"`
+
+	// CACert is the path to the CA certificate for verifying Metacrypt's TLS.
+	CACert string `toml:"ca_cert"`
+
+	// Mount is the CA engine mount name. Defaults to "pki".
+	Mount string `toml:"mount"`
+
+	// Issuer is the intermediate CA issuer name. Defaults to "infra".
+	Issuer string `toml:"issuer"`
+
+	// TokenPath is the path to the MCIAS service token file.
+	TokenPath string `toml:"token_path"`
+}
+
+// MCNSConfig holds the MCNS DNS integration settings for automated
+// DNS record registration. If ServerURL is empty, DNS registration
+// is disabled.
+type MCNSConfig struct {
+	// ServerURL is the MCNS API base URL (e.g. "https://localhost:28443").
+	ServerURL string `toml:"server_url"`
+
+	// CACert is the path to the CA certificate for verifying MCNS's TLS.
+	CACert string `toml:"ca_cert"`
+
+	// TokenPath is the path to the MCIAS service token file.
+	TokenPath string `toml:"token_path"`
+
+	// Zone is the DNS zone for service records. Defaults to "svc.mcp.metacircular.net".
+	Zone string `toml:"zone"`
+
+	// NodeAddr is the IP address to register as the A record value.
+	NodeAddr string `toml:"node_addr"`
+}
+
 // MCProxyConfig holds the mc-proxy connection settings.
 type MCProxyConfig struct {
 	// Socket is the path to the mc-proxy gRPC admin API Unix socket.
@@ -150,6 +192,15 @@ func applyAgentDefaults(cfg *AgentConfig) {
 	if cfg.MCProxy.CertDir == "" {
 		cfg.MCProxy.CertDir = "/srv/mc-proxy/certs"
 	}
+	if cfg.Metacrypt.Mount == "" {
+		cfg.Metacrypt.Mount = "pki"
+	}
+	if cfg.Metacrypt.Issuer == "" {
+		cfg.Metacrypt.Issuer = "infra"
+	}
+	if cfg.MCNS.Zone == "" {
+		cfg.MCNS.Zone = "svc.mcp.metacircular.net"
+	}
 }
 
 func applyAgentEnvOverrides(cfg *AgentConfig) {
@@ -180,6 +231,21 @@ func applyAgentEnvOverrides(cfg *AgentConfig) {
 	if v := os.Getenv("MCP_AGENT_MCPROXY_CERT_DIR"); v != "" {
 		cfg.MCProxy.CertDir = v
 	}
+	if v := os.Getenv("MCP_AGENT_METACRYPT_SERVER_URL"); v != "" {
+		cfg.Metacrypt.ServerURL = v
+	}
+	if v := os.Getenv("MCP_AGENT_METACRYPT_TOKEN_PATH"); v != "" {
+		cfg.Metacrypt.TokenPath = v
+	}
+	if v := os.Getenv("MCP_AGENT_MCNS_SERVER_URL"); v != "" {
+		cfg.MCNS.ServerURL = v
+	}
+	if v := os.Getenv("MCP_AGENT_MCNS_TOKEN_PATH"); v != "" {
+		cfg.MCNS.TokenPath = v
+	}
+	if v := os.Getenv("MCP_AGENT_MCNS_NODE_ADDR"); v != "" {
+		cfg.MCNS.NodeAddr = v
+	}
 }
 
 func validateAgentConfig(cfg *AgentConfig) error {

internal/config/config_test.go

@@ -163,6 +163,19 @@ func TestLoadAgentConfig(t *testing.T) {
 	if cfg.Log.Level != "debug" {
 		t.Fatalf("log.level: got %q", cfg.Log.Level)
 	}
+
+	// Metacrypt defaults when section is omitted.
+	if cfg.Metacrypt.Mount != "pki" {
+		t.Fatalf("metacrypt.mount default: got %q, want pki", cfg.Metacrypt.Mount)
+	}
+	if cfg.Metacrypt.Issuer != "infra" {
+		t.Fatalf("metacrypt.issuer default: got %q, want infra", cfg.Metacrypt.Issuer)
+	}
+
+	// MCNS defaults when section is omitted.
+	if cfg.MCNS.Zone != "svc.mcp.metacircular.net" {
+		t.Fatalf("mcns.zone default: got %q, want svc.mcp.metacircular.net", cfg.MCNS.Zone)
+	}
 }
 
 func TestCLIConfigValidation(t *testing.T) {
@@ -439,6 +452,155 @@ level = "info"
 	})
 }
 
+func TestAgentConfigMetacrypt(t *testing.T) {
+	cfgStr := `
+[server]
+grpc_addr = "0.0.0.0:9444"
+tls_cert  = "/srv/mcp/cert.pem"
+tls_key   = "/srv/mcp/key.pem"
+[database]
+path = "/srv/mcp/mcp.db"
+[mcias]
+server_url   = "https://mcias.metacircular.net:8443"
+service_name = "mcp-agent"
+[agent]
+node_name = "rift"
+[metacrypt]
+server_url = "https://metacrypt.metacircular.net:8443"
+ca_cert    = "/etc/mcp/metacircular-ca.pem"
+mount      = "custom-pki"
+issuer     = "custom-issuer"
+token_path = "/srv/mcp/metacrypt-token"
+`
+	path := writeTempConfig(t, cfgStr)
+	cfg, err := LoadAgentConfig(path)
+	if err != nil {
+		t.Fatalf("load: %v", err)
+	}
+
+	if cfg.Metacrypt.ServerURL != "https://metacrypt.metacircular.net:8443" {
+		t.Fatalf("metacrypt.server_url: got %q", cfg.Metacrypt.ServerURL)
+	}
+	if cfg.Metacrypt.CACert != "/etc/mcp/metacircular-ca.pem" {
+		t.Fatalf("metacrypt.ca_cert: got %q", cfg.Metacrypt.CACert)
+	}
+	if cfg.Metacrypt.Mount != "custom-pki" {
+		t.Fatalf("metacrypt.mount: got %q", cfg.Metacrypt.Mount)
+	}
+	if cfg.Metacrypt.Issuer != "custom-issuer" {
+		t.Fatalf("metacrypt.issuer: got %q", cfg.Metacrypt.Issuer)
+	}
+	if cfg.Metacrypt.TokenPath != "/srv/mcp/metacrypt-token" {
+		t.Fatalf("metacrypt.token_path: got %q", cfg.Metacrypt.TokenPath)
+	}
+}
+
+func TestAgentConfigMetacryptEnvOverrides(t *testing.T) {
+	minimal := `
+[server]
+grpc_addr = "0.0.0.0:9444"
+tls_cert  = "/srv/mcp/cert.pem"
+tls_key   = "/srv/mcp/key.pem"
+[database]
+path = "/srv/mcp/mcp.db"
+[mcias]
+server_url   = "https://mcias.metacircular.net:8443"
+service_name = "mcp-agent"
+[agent]
+node_name = "rift"
+`
+	t.Setenv("MCP_AGENT_METACRYPT_SERVER_URL", "https://override.metacrypt:8443")
+	t.Setenv("MCP_AGENT_METACRYPT_TOKEN_PATH", "/override/token")
+
+	path := writeTempConfig(t, minimal)
+	cfg, err := LoadAgentConfig(path)
+	if err != nil {
+		t.Fatalf("load: %v", err)
+	}
+
+	if cfg.Metacrypt.ServerURL != "https://override.metacrypt:8443" {
+		t.Fatalf("metacrypt.server_url: got %q", cfg.Metacrypt.ServerURL)
+	}
+	if cfg.Metacrypt.TokenPath != "/override/token" {
+		t.Fatalf("metacrypt.token_path: got %q", cfg.Metacrypt.TokenPath)
+	}
+}
+
+func TestAgentConfigMCNS(t *testing.T) {
+	cfgStr := `
+[server]
+grpc_addr = "0.0.0.0:9444"
+tls_cert  = "/srv/mcp/cert.pem"
+tls_key   = "/srv/mcp/key.pem"
+[database]
+path = "/srv/mcp/mcp.db"
+[mcias]
+server_url   = "https://mcias.metacircular.net:8443"
+service_name = "mcp-agent"
+[agent]
+node_name = "rift"
+[mcns]
+server_url = "https://localhost:28443"
+ca_cert    = "/srv/mcp/certs/metacircular-ca.pem"
+token_path = "/srv/mcp/metacrypt-token"
+zone       = "custom.zone"
+node_addr  = "10.0.0.1"
+`
+	path := writeTempConfig(t, cfgStr)
+	cfg, err := LoadAgentConfig(path)
+	if err != nil {
+		t.Fatalf("load: %v", err)
+	}
+
+	if cfg.MCNS.ServerURL != "https://localhost:28443" {
+		t.Fatalf("mcns.server_url: got %q", cfg.MCNS.ServerURL)
+	}
+	if cfg.MCNS.CACert != "/srv/mcp/certs/metacircular-ca.pem" {
+		t.Fatalf("mcns.ca_cert: got %q", cfg.MCNS.CACert)
+	}
+	if cfg.MCNS.Zone != "custom.zone" {
+		t.Fatalf("mcns.zone: got %q", cfg.MCNS.Zone)
+	}
+	if cfg.MCNS.NodeAddr != "10.0.0.1" {
+		t.Fatalf("mcns.node_addr: got %q", cfg.MCNS.NodeAddr)
+	}
+}
+
+func TestAgentConfigMCNSEnvOverrides(t *testing.T) {
+	minimal := `
+[server]
+grpc_addr = "0.0.0.0:9444"
+tls_cert  = "/srv/mcp/cert.pem"
+tls_key   = "/srv/mcp/key.pem"
+[database]
+path = "/srv/mcp/mcp.db"
+[mcias]
+server_url   = "https://mcias.metacircular.net:8443"
+service_name = "mcp-agent"
+[agent]
+node_name = "rift"
+`
+	t.Setenv("MCP_AGENT_MCNS_SERVER_URL", "https://override:28443")
+	t.Setenv("MCP_AGENT_MCNS_TOKEN_PATH", "/override/token")
+	t.Setenv("MCP_AGENT_MCNS_NODE_ADDR", "10.0.0.99")
+
+	path := writeTempConfig(t, minimal)
+	cfg, err := LoadAgentConfig(path)
+	if err != nil {
+		t.Fatalf("load: %v", err)
+	}
+
+	if cfg.MCNS.ServerURL != "https://override:28443" {
+		t.Fatalf("mcns.server_url: got %q", cfg.MCNS.ServerURL)
+	}
+	if cfg.MCNS.TokenPath != "/override/token" {
+		t.Fatalf("mcns.token_path: got %q", cfg.MCNS.TokenPath)
+	}
+	if cfg.MCNS.NodeAddr != "10.0.0.99" {
+		t.Fatalf("mcns.node_addr: got %q", cfg.MCNS.NodeAddr)
+	}
+}
+
 func TestDurationParsing(t *testing.T) {
 	tests := []struct {
 		input string

internal/servicedef/servicedef.go

@@ -210,7 +210,7 @@ func ToProto(def *ServiceDef) *mcpv1.ServiceSpec {
 		for _, r := range c.Routes {
 			cs.Routes = append(cs.Routes, &mcpv1.RouteSpec{
 				Name:     r.Name,
-				Port:     int32(r.Port),
+				Port:     int32(r.Port), //nolint:gosec // port range validated
 				Mode:     r.Mode,
 				Hostname: r.Hostname,
 			})

vendor/git.wntrmute.dev/mc/mc-proxy/gen/mc_proxy/v1/admin.pb.go

@@ -1449,7 +1449,7 @@ const file_proto_mc_proxy_v1_admin_proto_rawDesc = "" +
 	"\x0eListL7Policies\x12\".mc_proxy.v1.ListL7PoliciesRequest\x1a#.mc_proxy.v1.ListL7PoliciesResponse\x12P\n" +
 	"\vAddL7Policy\x12\x1f.mc_proxy.v1.AddL7PolicyRequest\x1a .mc_proxy.v1.AddL7PolicyResponse\x12Y\n" +
 	"\x0eRemoveL7Policy\x12\".mc_proxy.v1.RemoveL7PolicyRequest\x1a#.mc_proxy.v1.RemoveL7PolicyResponse\x12J\n" +
-	"\tGetStatus\x12\x1d.mc_proxy.v1.GetStatusRequest\x1a\x1e.mc_proxy.v1.GetStatusResponseB:Z8git.wntrmute.dev/mc/mc-proxy/gen/mc_proxy/v1;mcproxyv1b\x06proto3"
+	"\tGetStatus\x12\x1d.mc_proxy.v1.GetStatusRequest\x1a\x1e.mc_proxy.v1.GetStatusResponseB8Z6git.wntrmute.dev/mc/mc-proxy/gen/mc_proxy/v1;mcproxyv1b\x06proto3"
 
 var (
 	file_proto_mc_proxy_v1_admin_proto_rawDescOnce sync.Once

vendor/modules.txt

@@ -1,4 +1,4 @@
-# git.wntrmute.dev/mc/mc-proxy v1.1.0
+# git.wntrmute.dev/mc/mc-proxy v1.2.0
 ## explicit; go 1.25.7
 git.wntrmute.dev/mc/mc-proxy/client/mcproxy
 git.wntrmute.dev/mc/mc-proxy/gen/mc_proxy/v1