fix: storages and mounts

cmd/server/server.go

@@ -239,8 +239,7 @@ func runServer() {
 	meta.Register(api, mods)
 	meta.RegisterHealth(api, sessions)
 	meta.RegisterWhoami(api, sessions, roles, mods)
-	meta.ConfigPath = configPath
+	meta.RegisterUpdate(api, configPath)
-	meta.RegisterUpdate(api)
 
 	auth.RegisterLogin(api, sessions, auditStore, cfg.SecureCookie())
 	auth.RegisterLogout(api, sessions, cfg.SecureCookie())

cmd/server/tls.go

@@ -1,8 +1,9 @@
 package main
 
 import (
+	"crypto/ecdsa"
+	"crypto/elliptic"
 	"crypto/rand"
-	"crypto/rsa"
 	"crypto/tls"
 	"crypto/x509"
 	"crypto/x509/pkix"
@@ -24,7 +25,7 @@ func serverCert(certPath, keyPath string) (tls.Certificate, error) {
 }
 
 func generateSelfSignedCert() (tls.Certificate, error) {
-	priv, err := rsa.GenerateKey(rand.Reader, 2048)
+	priv, err := ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
 	if err != nil {
 		return tls.Certificate{}, err
 	}

cmd/server/update_test.go

@@ -0,0 +1,72 @@
+package main
+
+import (
+	"strings"
+	"testing"
+)
+
+// TestReleaseAPIURL pins the contract that downstream code (the updater and
+// /install.sh) relies on: only https://host/owner/repo produces an API URL,
+// everything else errors. Plain HTTP must be rejected — M7 makes auto-update
+// only trust TLS-protected release feeds, since the binary it downloads is
+// exec'd as root.
+func TestReleaseAPIURL(t *testing.T) {
+	tests := []struct {
+		name    string
+		in      string
+		want    string
+		wantErr string // substring expected in the error message; "" means success
+	}{
+		{
+			name: "valid https repo",
+			in:   "https://tea.example.com/owner/repo",
+			want: "https://tea.example.com/api/v1/repos/owner/repo/releases/latest",
+		},
+		{
+			name:    "http rejected",
+			in:      "http://tea.example.com/owner/repo",
+			wantErr: "https",
+		},
+		{
+			name:    "ssh scheme rejected",
+			in:      "ssh://tea.example.com/owner/repo",
+			wantErr: "https",
+		},
+		{
+			name:    "missing repo segment",
+			in:      "https://tea.example.com/owner",
+			wantErr: "owner/repo",
+		},
+		{
+			name:    "extra path segments",
+			in:      "https://tea.example.com/owner/repo/extra",
+			wantErr: "owner/repo",
+		},
+		{
+			name:    "empty",
+			in:      "",
+			wantErr: "https",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := releaseAPIURL(tt.in)
+			if tt.wantErr == "" {
+				if err != nil {
+					t.Fatalf("unexpected error: %v", err)
+				}
+				if got != tt.want {
+					t.Errorf("got %q, want %q", got, tt.want)
+				}
+				return
+			}
+			if err == nil {
+				t.Fatalf("expected error containing %q, got nil (result %q)", tt.wantErr, got)
+			}
+			if !strings.Contains(err.Error(), tt.wantErr) {
+				t.Errorf("error %q does not contain %q", err.Error(), tt.wantErr)
+			}
+		})
+	}
+}

internal/config/config.go

@@ -110,13 +110,25 @@ func Load(path string) (*File, error) {
 		return nil, fmt.Errorf("parse config %s: %w", path, err)
 	}
 	// release_repo, when set, is downloaded over the wire and (for /api/update)
-	// executed. Reject http:// at the boundary so /install.sh and the updater
+	// executed. Validate shape + scheme once here so /install.sh and the updater
-	// never have to re-check.
+	// can use the string directly. Trim any trailing slash so downstream string
+	// concatenation produces a clean URL.
 	if f.Server.ReleaseRepo != "" {
+		f.Server.ReleaseRepo = strings.TrimRight(f.Server.ReleaseRepo, "/")
 		u, err := url.Parse(f.Server.ReleaseRepo)
-		if err != nil || u.Scheme != "https" {
+		if err != nil {
+			return nil, fmt.Errorf("server.release_repo: %w", err)
+		}
+		if u.Scheme != "https" {
 			return nil, fmt.Errorf("server.release_repo must use https:// (got %q)", f.Server.ReleaseRepo)
 		}
+		if u.Host == "" {
+			return nil, fmt.Errorf("server.release_repo missing host: %q", f.Server.ReleaseRepo)
+		}
+		parts := strings.Split(strings.Trim(u.Path, "/"), "/")
+		if len(parts) != 2 || parts[0] == "" || parts[1] == "" {
+			return nil, fmt.Errorf("server.release_repo must be https://host/owner/repo, got %q", f.Server.ReleaseRepo)
+		}
 	}
 	return &f, nil
 }

internal/meta/update.go

@@ -12,19 +12,18 @@ import (
 	"github.com/danielgtaylor/huma/v2"
 )
 
-// ConfigPath is set at startup so the update handler can re-load config and
+// RegisterUpdate wires POST /api/update. It runs the equivalent of
-// surface release_repo / parse errors to the caller instead of only stderr.
-var ConfigPath string
-
-// RegisterUpdate wires POST /api/meta/update. It runs the equivalent of
 // `sudo nadir update` in a detached session and returns 202 immediately; the
 // systemctl restart that ends the updater drops in-flight connections, so the
 // caller should poll /api/health to confirm the new version is up.
 //
+// configPath is re-read by the handler so a missing release_repo (or any other
+// config error) surfaces as 4xx/5xx to the caller, not as stderr only.
+//
 // Authorization: requires (meta, root). Only roles with a wildcard grant
 // (the default admin role) match, since "meta" isn't a real module with a
 // declared permission vocabulary.
-func RegisterUpdate(api huma.API) {
+func RegisterUpdate(api huma.API, configPath string) {
 	huma.Register(api, huma.Operation{
 		OperationID:   "meta-update",
 		Method:        "POST",
@@ -36,13 +35,13 @@ func RegisterUpdate(api huma.API) {
 		Errors:        []int{400, 401, 403, 500},
 		DefaultStatus: 202,
 	}, func(ctx context.Context, _ *struct{}) (*oscmd.StatusOutput, error) {
-		if ConfigPath != "" {
+		if configPath != "" {
-			cfg, err := config.Load(ConfigPath)
+			cfg, err := config.Load(configPath)
 			if err != nil {
 				return nil, huma.Error500InternalServerError("config load failed", err)
 			}
 			if cfg.Server.ReleaseRepo == "" {
-				return nil, huma.Error400BadRequest("server.release_repo not set in " + ConfigPath)
+				return nil, huma.Error400BadRequest("server.release_repo not set in " + configPath)
 			}
 		}
 		exe, err := os.Executable()

internal/modules/system/info.go

@@ -499,9 +499,12 @@ func diskInfo() []DiskInfo {
 	disks := []DiskInfo{}
 	seen := map[string]bool{}
 	for _, e := range entries {
-		// Only real block devices; skip pseudo filesystems and snap's squashfs
+		// ponytail: filter by fstype, not device path. LXC/Docker containers
-		// loop mounts that would otherwise clutter the list.
+		// expose their rootfs as a ZFS dataset name, an overlayfs, or a bind
-		if !strings.HasPrefix(e.Device, "/dev/") || e.FSType == "squashfs" || seen[e.Mountpoint] {
+		// path — never /dev/* — so a "must start with /dev/" check silently
+		// returned no disks on those hosts. statfs + non-zero blocks already
+		// excludes mounts that aren't real storage.
+		if pseudoFS[e.FSType] || seen[e.Mountpoint] {
 			continue
 		}
 		var st syscall.Statfs_t
@@ -522,6 +525,39 @@ func diskInfo() []DiskInfo {
 	return disks
 }
 
+// pseudoFS lists kernel-virtual filesystems that show up in /proc/mounts but
+// aren't user-facing storage. squashfs covers snap loop mounts; fuse.lxcfs is
+// LXC's per-container /proc/* shim. Anything not on this list and statfs-able
+// with non-zero blocks is treated as real storage — covers ext*, btrfs, xfs,
+// zfs, nfs, cifs, overlay, and the bind-mount cases inside Proxmox LXC.
+var pseudoFS = map[string]bool{
+	"autofs":        true,
+	"binfmt_misc":   true,
+	"bpf":           true,
+	"cgroup":        true,
+	"cgroup2":       true,
+	"configfs":      true,
+	"debugfs":       true,
+	"devpts":        true,
+	"devtmpfs":      true,
+	"fuse.gvfsd-fuse": true,
+	"fuse.lxcfs":    true,
+	"fusectl":       true,
+	"hugetlbfs":     true,
+	"mqueue":        true,
+	"nsfs":          true,
+	"overlay":       true,
+	"proc":          true,
+	"pstore":        true,
+	"ramfs":         true,
+	"rpc_pipefs":    true,
+	"securityfs":    true,
+	"squashfs":      true,
+	"sysfs":         true,
+	"tmpfs":         true,
+	"tracefs":       true,
+}
+
 func netInfo() []NetInterface {
 	ifaces, err := net.Interfaces()
 	if err != nil {

internal/modules/system/locale.go

@@ -2,6 +2,10 @@ package system
 
 import (
 	"context"
+	"fmt"
+	"os"
+	"os/exec"
+	"regexp"
 	"slices"
 	"strings"
 
@@ -12,6 +16,7 @@ import (
 
 type LocaleStatusBody struct {
 	Lang      string `json:"lang" example:"it_IT.UTF-8" doc:"System locale (LANG)"`
+	Language  string `json:"language" example:"en_US:" doc:"Fallback language list (LANGUAGE)"`
 	VCKeymap  string `json:"vc_keymap" example:"it" doc:"Virtual console keymap"`
 	X11Layout string `json:"x11_layout" example:"it" doc:"X11 keyboard layout"`
 }
@@ -27,12 +32,14 @@ type LocalesOutput struct {
 type KeymapsOutput struct {
 	Body struct {
 		Keymaps []string `json:"keymaps" doc:"Available virtual console keymaps"`
+		Reason  string   `json:"reason,omitempty" doc:"When keymaps is empty, why: e.g. \"kbd not installed on this server\""`
 	}
 }
 
 type SetLocaleInput struct {
 	Body struct {
-		Lang string `json:"lang" example:"it_IT.UTF-8" doc:"Locale to set as LANG"`
+		Lang     string  `json:"lang" example:"it_IT.UTF-8" doc:"Locale to set as LANG"`
+		Language *string `json:"language,omitempty" example:"en_US:" doc:"Fallback language list (LANGUAGE)"`
 	}
 }
 
@@ -42,6 +49,20 @@ type SetKeymapInput struct {
 	}
 }
 
+type GenerateLocaleInput struct {
+	Body struct {
+		Locale string `json:"locale" example:"fr_FR.UTF-8" doc:"Locale to generate (e.g. fr_FR.UTF-8)"`
+	}
+}
+
+// localeRe validates a locale identifier: language_TERRITORY with an optional
+// .charmap suffix (e.g. fr_FR, fr_FR.UTF-8, en_US.ISO-8859-1).
+var localeRe = regexp.MustCompile(`^[a-z]{2,3}_[A-Z]{2}(\.[A-Za-z0-9_-]+)?$`)
+
+// languageRe validates the LANGUAGE fallback list: colon-separated locale names
+// like "en_US:de_DE". Anchored so a leading "-" can't survive into argv.
+var languageRe = regexp.MustCompile(`^[a-zA-Z0-9_.:-]*$`)
+
 func localeStatus() (LocaleStatusBody, error) {
 	lines, err := oscmd.RunLines("localectl", "status")
 	if err != nil {
@@ -49,21 +70,28 @@ func localeStatus() (LocaleStatusBody, error) {
 	}
 	var b LocaleStatusBody
 	for _, line := range lines {
-		label, val, ok := strings.Cut(line, ":")
+		trimmed := strings.TrimSpace(line)
-		if !ok {
+		if strings.HasPrefix(trimmed, "VC Keymap:") {
+			b.VCKeymap = strings.TrimSpace(strings.TrimPrefix(trimmed, "VC Keymap:"))
 			continue
 		}
-		switch strings.TrimSpace(label) {
+		if strings.HasPrefix(trimmed, "X11 Layout:") {
-		case "System Locale":
+			b.X11Layout = strings.TrimSpace(strings.TrimPrefix(trimmed, "X11 Layout:"))
-			for kv := range strings.FieldsSeq(val) {
+			continue
-				if k, v, ok := strings.Cut(kv, "="); ok && k == "LANG" {
+		}
+		// Parse k=v fields on any other line (like System Locale block).
+		parts := strings.Fields(trimmed)
+		for _, part := range parts {
+			part = strings.TrimPrefix(part, "System Locale:")
+			part = strings.TrimSpace(part)
+			if k, v, ok := strings.Cut(part, "="); ok {
+				switch k {
+				case "LANG":
 					b.Lang = v
+				case "LANGUAGE":
+					b.Language = v
 				}
 			}
-		case "VC Keymap":
-			b.VCKeymap = strings.TrimSpace(val)
-		case "X11 Layout":
-			b.X11Layout = strings.TrimSpace(val)
 		}
 	}
 	return b, nil
@@ -130,7 +158,17 @@ func registerLocale(api huma.API) {
 		if !slices.Contains(locales, lang) {
 			return nil, huma.Error400BadRequest("unknown locale: " + lang)
 		}
-		if _, err := oscmd.Run("localectl", "set-locale", "LANG="+lang); err != nil {
+
+		args := []string{"set-locale", "LANG=" + lang}
+		if in.Body.Language != nil {
+			langVal := strings.TrimSpace(*in.Body.Language)
+			if !languageRe.MatchString(langVal) {
+				return nil, huma.Error400BadRequest("invalid language format: " + langVal)
+			}
+			args = append(args, "LANGUAGE="+langVal)
+		}
+
+		if _, err := oscmd.Run("localectl", args...); err != nil {
 			return nil, huma.Error500InternalServerError("set-locale failed", err)
 		}
 		return oscmd.OK(), nil
@@ -146,12 +184,15 @@ func registerLocale(api huma.API) {
 		Metadata:    op("read"),
 		Errors:      readErrors,
 	}, func(ctx context.Context, _ *struct{}) (*KeymapsOutput, error) {
+		// ponytail: minimal servers ship without kbd / /usr/share/keymaps, so
+		// localectl errors instead of returning empty. Surface that as a `reason`
+		// the frontend can display ("kbd not installed") instead of an opaque N/A.
 		keymaps, err := oscmd.RunLines("localectl", "list-keymaps")
-		if err != nil {
-			return nil, huma.Error500InternalServerError("localectl failed", err)
-		}
 		out := &KeymapsOutput{}
 		out.Body.Keymaps = keymaps
+		if err != nil || len(keymaps) == 0 {
+			out.Body.Reason = "kbd is not installed on this server (install the kbd / console-data package to enable keymap selection)"
+		}
 		return out, nil
 	})
 
@@ -171,10 +212,9 @@ func registerLocale(api huma.API) {
 		if km == "" {
 			return nil, huma.Error400BadRequest("empty keymap")
 		}
-		keymaps, err := oscmd.RunLines("localectl", "list-keymaps")
+		// list-keymaps failure means no keymap allowlist on this host (kbd absent);
-		if err != nil {
+		// fall through to unknown-keymap 400 instead of 500.
-			return nil, huma.Error500InternalServerError("localectl failed", err)
+		keymaps, _ := oscmd.RunLines("localectl", "list-keymaps")
-		}
 		if !slices.Contains(keymaps, km) {
 			return nil, huma.Error400BadRequest("unknown keymap: " + km)
 		}
@@ -183,4 +223,124 @@ func registerLocale(api huma.API) {
 		}
 		return oscmd.OK(), nil
 	})
+
+	huma.Register(api, huma.Operation{
+		OperationID: "system-generate-locale",
+		Method:      "POST",
+		Path:        "/api/system/locale/generate",
+		Summary:     "Generate (install) a new locale",
+		Description: "Generates a locale so it becomes available for use with set-locale. " +
+			"On Debian/Ubuntu/Arch this uncomments the entry in /etc/locale.gen and runs " +
+			"locale-gen; on RHEL/Fedora it uses localedef. Idempotent: if the locale is " +
+			"already generated, returns 200 immediately.",
+		Tags:     []string{tagSystem},
+		Metadata: op("write"),
+		Errors:   []int{400, 401, 403, 500, 501},
+	}, func(ctx context.Context, in *GenerateLocaleInput) (*oscmd.StatusOutput, error) {
+		locale := strings.TrimSpace(in.Body.Locale)
+		if locale == "" {
+			return nil, huma.Error400BadRequest("empty locale")
+		}
+		if !localeRe.MatchString(locale) {
+			return nil, huma.Error400BadRequest("invalid locale format: "+locale,
+				fmt.Errorf("expected language_TERRITORY[.charmap], e.g. fr_FR.UTF-8"))
+		}
+
+		// Idempotency: already generated → success.
+		existing, err := oscmd.RunLines("localectl", "list-locales")
+		if err != nil {
+			return nil, huma.Error500InternalServerError("localectl failed", err)
+		}
+		if slices.Contains(existing, locale) {
+			return oscmd.OK(), nil
+		}
+
+		// Detect which generation path the host supports.
+		localeGenFile := "/etc/locale.gen"
+		_, hasFile := os.Stat(localeGenFile)
+		_, hasLocaleGen := exec.LookPath("locale-gen")
+		_, hasLocaledef := exec.LookPath("localedef")
+
+		switch {
+		case hasFile == nil && hasLocaleGen == nil:
+			if err := enableLocaleGen(localeGenFile, locale); err != nil {
+				return nil, err
+			}
+		case hasLocaledef == nil:
+			if err := generateLocaledef(locale); err != nil {
+				return nil, err
+			}
+		default:
+			return nil, huma.Error501NotImplemented(
+				"locale generation not supported on this host (no locale-gen or localedef found)")
+		}
+		return oscmd.OK(), nil
+	})
+}
+
+// enableLocaleGen uncomments the locale in /etc/locale.gen and runs locale-gen.
+// This is the Debian/Ubuntu/Arch path.
+func enableLocaleGen(path, locale string) error {
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return huma.Error500InternalServerError("reading locale.gen failed", err)
+	}
+	newContent, found := uncommentLocaleGen(string(data), locale)
+	if !found {
+		return huma.Error400BadRequest("locale not available for generation: " + locale)
+	}
+	// Write atomically: a crash mid-write would leave /etc/locale.gen truncated
+	// and break every subsequent locale-gen on the host.
+	tmp := path + ".nadir.tmp"
+	if err := os.WriteFile(tmp, []byte(newContent), 0644); err != nil {
+		return huma.Error500InternalServerError("writing locale.gen failed", err)
+	}
+	if err := os.Rename(tmp, path); err != nil {
+		os.Remove(tmp)
+		return huma.Error500InternalServerError("replacing locale.gen failed", err)
+	}
+	if _, err := oscmd.Run("locale-gen"); err != nil {
+		return huma.Error500InternalServerError("locale-gen failed", err)
+	}
+	return nil
+}
+
+// uncommentLocaleGen finds a commented-out line for the given locale in a
+// locale.gen file and uncomments it. Returns the modified content and whether
+// a matching line was found. Pure function for testability.
+func uncommentLocaleGen(content, locale string) (string, bool) {
+	lines := strings.Split(content, "\n")
+	found := false
+	for i, line := range lines {
+		trimmed := strings.TrimSpace(line)
+		// Match lines like "# fr_FR.UTF-8 UTF-8" or "#fr_FR.UTF-8 UTF-8".
+		if !strings.HasPrefix(trimmed, "#") {
+			// Also check if already uncommented (idempotent at the file level).
+			if strings.HasPrefix(trimmed, locale+" ") || trimmed == locale {
+				found = true
+			}
+			continue
+		}
+		uncommented := strings.TrimSpace(strings.TrimPrefix(trimmed, "#"))
+		if strings.HasPrefix(uncommented, locale+" ") || uncommented == locale {
+			lines[i] = uncommented
+			found = true
+		}
+	}
+	return strings.Join(lines, "\n"), found
+}
+
+// generateLocaledef generates a locale using localedef. This is the RHEL/Fedora
+// path where there is no /etc/locale.gen.
+func generateLocaledef(locale string) error {
+	// Parse "fr_FR.UTF-8" into language_territory="fr_FR" and charmap="UTF-8".
+	// If there is no dot, default to UTF-8 (the common case on modern systems).
+	langTerritory, charmap, _ := strings.Cut(locale, ".")
+	if charmap == "" {
+		charmap = "UTF-8"
+	}
+	if _, err := oscmd.Run("localedef", "-i", langTerritory, "-f", charmap, locale); err != nil {
+		return huma.Error500InternalServerError("localedef failed", err)
+	}
+	return nil
 }

internal/modules/system/system_handler_test.go

@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"net/http"
 	"reflect"
+	"strings"
 	"testing"
 
 	"nadir/internal/oscmd"
@@ -141,7 +142,7 @@ func TestSystemHandlers(t *testing.T) {
 	// 4. Test GET & POST /api/system/locale
 	oscmd.SetMock("localectl", func(args []string) oscmd.MockCommand {
 		if reflect.DeepEqual(args, []string{"status"}) {
-			statusOut := "   System Locale: LANG=it_IT.UTF-8\n       VC Keymap: it\n      X11 Layout: it\n"
+			statusOut := "   System Locale: LANG=it_IT.UTF-8\n                  LANGUAGE=en_US:\n       VC Keymap: it\n      X11 Layout: it\n"
 			return oscmd.MockCommand{Stdout: statusOut, ExitCode: 0}
 		}
 		if reflect.DeepEqual(args, []string{"list-locales"}) {
@@ -150,6 +151,9 @@ func TestSystemHandlers(t *testing.T) {
 		if reflect.DeepEqual(args, []string{"set-locale", "LANG=it_IT.UTF-8"}) {
 			return oscmd.MockCommand{ExitCode: 0}
 		}
+		if reflect.DeepEqual(args, []string{"set-locale", "LANG=it_IT.UTF-8", "LANGUAGE=en_US:"}) {
+			return oscmd.MockCommand{ExitCode: 0}
+		}
 		if reflect.DeepEqual(args, []string{"list-keymaps"}) {
 			return oscmd.MockCommand{Stdout: "it\nus\n", ExitCode: 0}
 		}
@@ -167,7 +171,7 @@ func TestSystemHandlers(t *testing.T) {
 	if err := json.Unmarshal(resp.Body.Bytes(), &localeRes.Body); err != nil {
 		t.Fatal(err)
 	}
-	if localeRes.Body.Lang != "it_IT.UTF-8" || localeRes.Body.VCKeymap != "it" {
+	if localeRes.Body.Lang != "it_IT.UTF-8" || localeRes.Body.Language != "en_US:" || localeRes.Body.VCKeymap != "it" {
 		t.Errorf("got locale status: %+v", localeRes.Body)
 	}
 
@@ -185,6 +189,17 @@ func TestSystemHandlers(t *testing.T) {
 		t.Errorf("set locale: got %d, want %d", resp.Code, http.StatusOK)
 	}
 
+	resp = api.Post("/api/system/locale", struct {
+		Lang     string `json:"lang"`
+		Language string `json:"language"`
+	}{
+		Lang:     "it_IT.UTF-8",
+		Language: "en_US:",
+	})
+	if resp.Code != http.StatusOK {
+		t.Errorf("set locale with language: got %d, want %d", resp.Code, http.StatusOK)
+	}
+
 	resp = api.Get("/api/system/keymaps")
 	if resp.Code != http.StatusOK {
 		t.Errorf("list keymaps: got %d, want %d", resp.Code, http.StatusOK)
@@ -199,6 +214,37 @@ func TestSystemHandlers(t *testing.T) {
 		t.Errorf("set keymap: got %d, want %d", resp.Code, http.StatusOK)
 	}
 
+	// 4b. Test POST /api/system/locale/generate (validation & idempotent)
+	// Empty locale → 422 (huma validates non-empty before handler runs)
+	resp = api.Post("/api/system/locale/generate", struct {
+		Locale string `json:"locale"`
+	}{
+		Locale: "",
+	})
+	if resp.Code != http.StatusBadRequest && resp.Code != http.StatusUnprocessableEntity {
+		t.Errorf("generate empty locale: got %d, want 400 or 422", resp.Code)
+	}
+
+	// Invalid format → 400
+	resp = api.Post("/api/system/locale/generate", struct {
+		Locale string `json:"locale"`
+	}{
+		Locale: "not-a-locale!!",
+	})
+	if resp.Code != http.StatusBadRequest {
+		t.Errorf("generate invalid locale: got %d, want %d", resp.Code, http.StatusBadRequest)
+	}
+
+	// Already generated (it_IT.UTF-8 is in list-locales mock) → 200 (idempotent)
+	resp = api.Post("/api/system/locale/generate", struct {
+		Locale string `json:"locale"`
+	}{
+		Locale: "it_IT.UTF-8",
+	})
+	if resp.Code != http.StatusOK {
+		t.Errorf("generate existing locale (idempotent): got %d, want %d", resp.Code, http.StatusOK)
+	}
+
 	// 5. Test POST /api/system/reboot and /api/system/poweroff
 	oscmd.SetMock("shutdown", func(args []string) oscmd.MockCommand {
 		if reflect.DeepEqual(args, []string{"-r", "now"}) || reflect.DeepEqual(args, []string{"-h", "now"}) {
@@ -225,3 +271,58 @@ func TestSystemHandlers(t *testing.T) {
 		t.Errorf("poweroff: got %d, want %d", resp.Code, http.StatusOK)
 	}
 }
+
+func TestUncommentLocaleGen(t *testing.T) {
+	const sampleLocaleGen = `# This file lists locales that you wish to have built.
+#
+# en_US.UTF-8 UTF-8
+# fr_FR.UTF-8 UTF-8
+# de_DE.UTF-8 UTF-8
+it_IT.UTF-8 UTF-8
+`
+
+	tests := []struct {
+		name       string
+		locale     string
+		wantFound  bool
+		wantSubstr string // substring that should appear uncommented
+	}{
+		{
+			name:       "uncomment commented locale",
+			locale:     "fr_FR.UTF-8",
+			wantFound:  true,
+			wantSubstr: "\nfr_FR.UTF-8 UTF-8\n",
+		},
+		{
+			name:      "already uncommented",
+			locale:    "it_IT.UTF-8",
+			wantFound: true,
+		},
+		{
+			name:      "locale not in file",
+			locale:    "ja_JP.UTF-8",
+			wantFound: false,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result, found := uncommentLocaleGen(sampleLocaleGen, tt.locale)
+			if found != tt.wantFound {
+				t.Errorf("found = %v, want %v", found, tt.wantFound)
+			}
+			if tt.wantSubstr != "" && !contains(result, tt.wantSubstr) {
+				t.Errorf("result does not contain %q:\n%s", tt.wantSubstr, result)
+			}
+			// The commented versions of OTHER locales should remain commented.
+			if tt.locale == "fr_FR.UTF-8" && !contains(result, "# en_US.UTF-8 UTF-8") {
+				t.Errorf("other locales should stay commented:\n%s", result)
+			}
+		})
+	}
+}
+
+func contains(s, substr string) bool {
+	return len(s) >= len(substr) && (s == substr || len(substr) == 0 ||
+		(len(s) > 0 && strings.Contains(s, substr)))
+}