Remove unused hostname_prefix from server types and add duplicate checking

The HostnamePrefix field on ServerType was loaded from YAML but never used —
hostnames are user-provided. This removes the field and adds explicit
duplicate checks (hostname + MAC) with clear per-field error messages in
both the JSON API and web UI, backed by a new GetByHostname store method
with case-insensitive matching.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

README.md

@@ -78,14 +78,12 @@ server_types:
     boot_disk: "/dev/nvme0n1"
     management_nic: "enp2s0"
     gpu: false
-    hostname_prefix: "pve-ms"
 
   minisforum-um790:
     display_name: "Minisforum UM790 Pro"
     boot_disk: "/dev/nvme0n1"
     management_nic: "enp1s0"
     gpu: true
-    hostname_prefix: "pve-um"
 ```
 
 ### Run

deploy/server-types.example.yaml

@@ -4,7 +4,6 @@ server_types:
     boot_disk: "/dev/nvme0n1"
     management_nic: "enp2s0"
     gpu: false
-    hostname_prefix: "pve-ms"
     expected_nics:
       - name: "enp2s0"
         speed: "2500"
@@ -16,7 +15,6 @@ server_types:
     boot_disk: "/dev/nvme0n1"
     management_nic: "enp1s0"
     gpu: true
-    hostname_prefix: "pve-um"
     expected_nics:
       - name: "enp1s0"
         speed: "2500"

internal/api/hosts.go

@@ -65,6 +65,14 @@ func (a *HostAPI) Create(w http.ResponseWriter, r *http.Request) {
 		writeJSONErr(w, http.StatusBadRequest, "unknown server_type")
 		return
 	}
+	if existing, err := a.Hosts.GetByHostname(r.Context(), req.Hostname); err == nil && existing != nil {
+		writeJSONErr(w, http.StatusConflict, "a host with this hostname already exists")
+		return
+	}
+	if existing, err := a.Hosts.GetByMAC(r.Context(), req.MAC); err == nil && existing != nil {
+		writeJSONErr(w, http.StatusConflict, "a host with this MAC address already exists")
+		return
+	}
 
 	id, err := a.Hosts.Create(r.Context(), model.Host{
 		Hostname:   req.Hostname,

internal/api/smoke_test.go

@@ -134,7 +134,6 @@ func mustLoadServerTypes(t *testing.T, dir string) *config.ServerTypeRegistry {
     boot_disk: "/dev/sda"
     management_nic: "eth0"
     gpu: false
-    hostname_prefix: "pve-test"
 `)
 	if err := writeTestFile(path, content); err != nil {
 		t.Fatal(err)
@@ -337,6 +336,82 @@ func TestOperationNotFound(t *testing.T) {
 	resp.Body.Close()
 }
 
+func TestDuplicateHostnameRejected(t *testing.T) {
+	ts := newTestServer(t)
+	defer ts.Close()
+
+	body := `{"hostname":"pve-dup-01","mac":"aa:bb:cc:dd:ee:d1","server_type":"test-type"}`
+	resp, err := http.Post(ts.URL+"/api/hosts", "application/json", bytes.NewBufferString(body))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if resp.StatusCode != http.StatusCreated {
+		t.Fatalf("first create: got %d, want %d", resp.StatusCode, http.StatusCreated)
+	}
+	resp.Body.Close()
+
+	body = `{"hostname":"pve-dup-01","mac":"aa:bb:cc:dd:ee:d2","server_type":"test-type"}`
+	resp, err = http.Post(ts.URL+"/api/hosts", "application/json", bytes.NewBufferString(body))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if resp.StatusCode != http.StatusConflict {
+		t.Fatalf("dup hostname: got %d, want %d", resp.StatusCode, http.StatusConflict)
+	}
+	var errResp map[string]any
+	json.NewDecoder(resp.Body).Decode(&errResp)
+	resp.Body.Close()
+	if msg, _ := errResp["error"].(string); msg != "a host with this hostname already exists" {
+		t.Fatalf("dup hostname error = %q, want specific hostname message", msg)
+	}
+}
+
+func TestDuplicateMACRejected(t *testing.T) {
+	ts := newTestServer(t)
+	defer ts.Close()
+
+	body := `{"hostname":"pve-mac-01","mac":"aa:bb:cc:dd:ee:e1","server_type":"test-type"}`
+	resp, err := http.Post(ts.URL+"/api/hosts", "application/json", bytes.NewBufferString(body))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if resp.StatusCode != http.StatusCreated {
+		t.Fatalf("first create: got %d, want %d", resp.StatusCode, http.StatusCreated)
+	}
+	resp.Body.Close()
+
+	body = `{"hostname":"pve-mac-02","mac":"aa:bb:cc:dd:ee:e1","server_type":"test-type"}`
+	resp, err = http.Post(ts.URL+"/api/hosts", "application/json", bytes.NewBufferString(body))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if resp.StatusCode != http.StatusConflict {
+		t.Fatalf("dup MAC: got %d, want %d", resp.StatusCode, http.StatusConflict)
+	}
+	var errResp map[string]any
+	json.NewDecoder(resp.Body).Decode(&errResp)
+	resp.Body.Close()
+	if msg, _ := errResp["error"].(string); msg != "a host with this MAC address already exists" {
+		t.Fatalf("dup MAC error = %q, want specific MAC message", msg)
+	}
+}
+
+func TestDuplicateHostnameCaseInsensitive(t *testing.T) {
+	ts := newTestServer(t)
+	defer ts.Close()
+
+	body := `{"hostname":"pve-case-01","mac":"aa:bb:cc:dd:ee:c1","server_type":"test-type"}`
+	resp, _ := http.Post(ts.URL+"/api/hosts", "application/json", bytes.NewBufferString(body))
+	resp.Body.Close()
+
+	body = `{"hostname":"PVE-CASE-01","mac":"aa:bb:cc:dd:ee:c2","server_type":"test-type"}`
+	resp, _ = http.Post(ts.URL+"/api/hosts", "application/json", bytes.NewBufferString(body))
+	if resp.StatusCode != http.StatusConflict {
+		t.Fatalf("case-insensitive dup: got %d, want %d", resp.StatusCode, http.StatusConflict)
+	}
+	resp.Body.Close()
+}
+
 func itoa(i int64) string {
 	return fmt.Sprintf("%d", i)
 }

internal/api/ui.go

@@ -74,6 +74,22 @@ func (u *UI) CreateHost(w http.ResponseWriter, r *http.Request) {
 		}))
 		return
 	}
+	if existing, err := u.Hosts.GetByHostname(r.Context(), hostname); err == nil && existing != nil {
+		errs = append(errs, "A host with this hostname already exists")
+	}
+	if existing, err := u.Hosts.GetByMAC(r.Context(), mac); err == nil && existing != nil {
+		errs = append(errs, "A host with this MAC address already exists")
+	}
+	if len(errs) > 0 {
+		types := u.ServerTypes.Keys()
+		renderHTML(w, hostFormPage(types, strings.Join(errs, "; "), &model.Host{
+			Hostname:   hostname,
+			MAC:        mac,
+			ServerType: serverType,
+			Notes:      notes,
+		}))
+		return
+	}
 
 	_, err := u.Hosts.Create(r.Context(), model.Host{
 		Hostname:   hostname,

internal/model/model.go

@@ -90,7 +90,6 @@ type ServerType struct {
 	BootDisk      string   `yaml:"boot_disk"`
 	ManagementNIC string   `yaml:"management_nic"`
 	GPU           bool     `yaml:"gpu"`
-	HostnamePrefix string   `yaml:"hostname_prefix"`
 	ExpectedNICs  []NICDef `yaml:"expected_nics"`
 }
 

internal/store/hosts.go

@@ -87,6 +87,18 @@ func (s *Hosts) GetByMAC(ctx context.Context, mac string) (*model.Host, error) {
 	return &h, nil
 }
 
+func (s *Hosts) GetByHostname(ctx context.Context, hostname string) (*model.Host, error) {
+	row := s.DB.QueryRowContext(ctx, `SELECT `+hostColumns+` FROM hosts WHERE LOWER(hostname) = ?`, normalizeHostname(hostname))
+	var h model.Host
+	if err := scanHost(row, &h); err != nil {
+		if err == sql.ErrNoRows {
+			return nil, ErrNotFound
+		}
+		return nil, fmt.Errorf("get host by hostname: %w", err)
+	}
+	return &h, nil
+}
+
 func (s *Hosts) UpdateState(ctx context.Context, id int64, state model.HostState) error {
 	res, err := s.DB.ExecContext(ctx, `UPDATE hosts SET state = ?, updated_at = strftime('%Y-%m-%dT%H:%M:%SZ','now') WHERE id = ?`, state, id)
 	if err != nil {
@@ -143,3 +155,7 @@ func (s *Hosts) Delete(ctx context.Context, id int64) error {
 func normalizeMAC(m string) string {
 	return strings.ToLower(strings.TrimSpace(m))
 }
+
+func normalizeHostname(h string) string {
+	return strings.ToLower(strings.TrimSpace(h))
+}