refactor: cleanup

src/lib/backend-errors.ts

@@ -11,6 +11,10 @@ export type BackendErrorCode =
   | "PROFILE_NOT_PROTECTED"
   | "PROFILE_ALREADY_PROTECTED"
   | "PROFILE_RUNNING"
+  | "PROFILE_PAIRED_TWICE"
+  | "URL_SCHEME_NOT_ALLOWED"
+  | "TOOL_IS_LOCAL_ONLY"
+  | "TYPING_TOO_LONG"
   | "PROFILE_EPHEMERAL"
   | "PROFILE_MISSING_SALT"
   | "PROFILE_LOCKED"
@@ -41,12 +45,17 @@ export type BackendErrorCode =
   | "EXTENSION_PATH_HAS_COMMA"
   | "EXTENSION_LINK_REQUIRES_DIRECTORY"
   | "EXTENSION_LINKED_CANNOT_SYNC"
+  | "EXTENSION_URL_INVALID"
+  | "EXTENSION_DOWNLOAD_FAILED"
+  | "EXTENSION_NOT_AN_EXTENSION"
+  | "EXTENSION_TOO_LARGE"
   | "CANNOT_MODIFY_CLOUD_MANAGED_PROXY"
   | "SYNC_LOCKED_BY_PROFILE"
   | "SYNC_NOT_CONFIGURED"
   | "FINGERPRINT_REQUIRES_PRO"
   | "PROXY_NOT_WORKING"
   | "PROXY_PAYMENT_REQUIRED"
+  | "PROXY_TLS_HANDSHAKE_FAILED"
   | "VPN_NOT_WORKING"
   | "CAMOUFOX_IMPORT_DEPRECATED"
   | "PROXY_SIDECAR_VERSION_MISMATCH"
@@ -77,9 +86,19 @@ export type BackendErrorCode =
   | "MCP_SERVER_NOT_RUNNING"
   | "MCP_PORT_UNAVAILABLE"
   | "MCP_CONFIGURATION_UNAVAILABLE"
+  // Local MCP has been removed in favor of remote MCP.
+  | "MCP_LOCAL_REMOVED"
   | "MCP_AGENT_UNKNOWN"
   | "MCP_AGENT_INSTALL_FAILED"
   | "MCP_AGENT_REMOVE_FAILED"
+  | "MCP_REMOTE_REQUIRES_SIGN_IN"
+  | "MCP_REMOTE_UNAUTHORIZED"
+  | "MCP_REMOTE_SLOT_TAKEN"
+  | "MCP_REMOTE_NOT_ENTITLED"
+  | "MCP_REMOTE_UNREACHABLE"
+  | "MCP_REMOTE_KEY_MISSING"
+  | "MCP_REMOTE_KEY_LIMIT"
+  | "MCP_REMOTE_KEY_UNAVAILABLE"
   | "VLESS_CONFIG_INVALID"
   | "XRAY_UNAVAILABLE"
   | "XRAY_UNSUPPORTED_OS"
@@ -89,6 +108,27 @@ export type BackendErrorCode =
   | "CLOUD_REQUEST_FAILED"
   | "REMOTE_RATE_LIMITED"
   | "REMOTE_NO_CAPACITY"
+  // The deployment has no fleet credential at all, which is not the same as a
+  // busy fleet — telling the two apart is the whole reason it is coded.
+  | "REMOTE_NOT_CONFIGURED"
+  // The launch was refused for a reason the user cannot wait out (a bad
+  // request, a profile that will not run). `params.detail` carries the
+  // server's own words.
+  | "REMOTE_LAUNCH_REFUSED"
+  // The fleet never answered a launch (timeout or connection failure), even on
+  // the retry that de-duplicates on the idempotency key. Nothing was refused;
+  // the user can only try again.
+  | "REMOTE_FLEET_UNREACHABLE"
+  // Already at the account's concurrent-session ceiling. `params.limit`/`live`.
+  | "REMOTE_CONCURRENCY_LIMIT"
+  // Asked to drive a session that has not reached `live` yet.
+  | "REMOTE_SESSION_NOT_DRIVABLE"
+  // The profile's OS is not one a leased host serves (e.g. an android
+  // fingerprint). `params.platform` names it.
+  | "REMOTE_PLATFORM_UNSUPPORTED"
+  // Sync is on but no upload has ever completed, so a remote host would pull an
+  // empty profile and overwrite the real one. Refused before any lease.
+  | "REMOTE_PROFILE_NOT_SYNCED"
   | "REMOTE_NOT_ENTITLED"
   | "REMOTE_INTERACTIVE_NOT_ENTITLED"
   // The profile's exit only resolves on this computer, so a leased host cannot
@@ -96,6 +136,11 @@ export type BackendErrorCode =
   // name different features, and a user told their "Cookie Bot" needs a public
   // proxy while they were opening a browser by hand cannot act on that.
   | "REMOTE_REQUIRES_REMOTE_EXIT_NODE"
+  // The exit's PROTOCOL is the problem, not its address. A VLESS server is as
+  // publicly routable as any other, so the reachability check passes and the
+  // sentence above sends the user to fix the one part of their config that was
+  // already right. `params.kind` names the protocol.
+  | "REMOTE_PROXY_KIND_UNSUPPORTED"
   | "REMOTE_SESSION_REFUSED"
   | "REMOTE_SESSION_NOT_FOUND"
   | "REMOTE_SESSION_CONFLICT"
@@ -126,13 +171,34 @@ export type BackendErrorCode =
   // "attach a proxy" is unactionable advice for someone whose proxy is plainly
   // attached.
   | "COOKIE_BOT_REQUIRES_REMOTE_EXIT_NODE"
-  // The server's own names for two refusals it throws from `putSchedule`,
-  // `updateProfileState` and `runNow`. `COOKIE_BOT_REQUIRES_PROXY` is the
+  // ...and its twin for an exit whose PROTOCOL no host can speak. Kept apart
+  // from the address refusal because a VLESS server is publicly routable: the
+  // user is not being asked for a different address, they are being asked for a
+  // different kind of exit. `params.kind` names it.
+  | "COOKIE_BOT_PROXY_KIND_UNSUPPORTED"
+  // The server's own names for two refusals the schedule, profile-state and
+  // run-now routes can return. `COOKIE_BOT_REQUIRES_PROXY` is the
   // server-side twin of the local `COOKIE_BOT_REQUIRES_EXIT_NODE` precondition;
   // without a case here the single most important refusal in the feature
   // rendered as the raw machine identifier.
   | "COOKIE_BOT_REQUIRES_PROXY"
   | "COOKIE_BOT_TOUCH_FINGERPRINT_UNSUPPORTED"
+  // Agent runs. The first ten are the server's own refusals; the last two are
+  // how a bodyless status on a recipe route is classified client-side, because
+  // "that run does not exist" is the wrong sentence to show someone editing a
+  // saved goal.
+  | "AGENT_NOT_ENTITLED"
+  | "AGENT_NOT_CONFIGURED"
+  | "AGENT_TARGET_OFFLINE"
+  | "AGENT_BUDGET_EXCEEDED"
+  | "AGENT_RUN_LIMIT_REACHED"
+  | "AGENT_RUN_NOT_FOUND"
+  | "AGENT_RUN_NOT_CANCELLABLE"
+  | "AGENT_GOAL_INVALID"
+  | "AGENT_BUDGET_INVALID"
+  | "AGENT_TOKEN_PROFILE_MISMATCH"
+  | "AGENT_RECIPE_INVALID"
+  | "AGENT_RECIPE_NOT_FOUND"
   | "FINGERPRINT_EXIT_MISMATCH"
   // The launch refuses instead of opening a window on an unmanaged device: a
   // silent fallback would leave the user browsing a random fingerprint while
@@ -140,20 +206,56 @@ export type BackendErrorCode =
   // can have. `detail` carries the underlying browser error for support.
   | "WAYFERN_FINGERPRINT_APPLY_FAILED"
   | "WAYFERN_FINGERPRINT_GENERATION_FAILED"
-  // Its own code rather than a generation failure: the browser's quota block is
-  // account-wide and lasts 24 hours, so "try again" is wrong advice, and a user
-  // whose every profile refuses at once has to be told this is one limit and
-  // not a broken install.
+  // Its own code rather than a generation failure: the block applies to the
+  // whole account rather than one profile, so "try again" is wrong advice, and
+  // a user whose every profile refuses at once has to be told this is one
+  // limit and not a broken install.
   | "WAYFERN_GENERATION_LIMIT_REACHED"
-  // A cross-OS claim needs a signed plan token, so an expired or offline
-  // session cannot apply one. Distinct from the generic apply failure because
+  // A cross-OS claim needs an active signed-in session, so an expired or
+  // offline one cannot apply it. Distinct from the generic apply failure because
   // signing in again is the fix; `detail` names the claimed OS.
   | "WAYFERN_CROSS_OS_REQUIRES_PLAN"
+  | "WAYFERN_IDENTITY_REFUSED"
+  | "PROFILE_EXPORT_FAILED"
+  | "PROFILE_EXPORT_TOO_LARGE"
+  | "PROFILE_IMPORT_FAILED"
+  | "PROFILE_IMPORT_TOO_NEW"
+  | "PROFILE_IMPORT_UNSAFE_ARCHIVE"
+  | "RECORDING_ALREADY_RUNNING"
+  | "PROFILE_NOT_RUNNING"
+  | "WAYFERN_152_REQUIRED"
+  | "RECORDING_FAILED"
   | "LAUNCH_CONSENT_EXPIRED"
   | "VPN_WORKER_START_FAILED"
   | "EXIT_PROBE_FAILED"
   | "CAMOUFOX_REMOVED"
   | "NO_E2E_PASSWORD_SET"
+  | "TRASH_ENTRY_NOT_FOUND"
+  | "TRASH_RESTORE_CONFLICT"
+  // Moving the data directory. Every refusal is its own code because every one
+  // of them has a different fix: close the browsers, wait for the sync, pick
+  // somewhere else, free some space.
+  | "DATA_ROOT_SAME_AS_CURRENT"
+  | "DATA_ROOT_DESTINATION_INSIDE_SOURCE"
+  | "DATA_ROOT_BROWSER_RUNNING"
+  | "DATA_ROOT_SYNC_IN_PROGRESS"
+  // `params.required` / `params.available`, both in bytes as strings.
+  | "DATA_ROOT_INSUFFICIENT_SPACE"
+  | "DATA_ROOT_DESTINATION_NOT_WRITABLE"
+  | "DATA_ROOT_DESTINATION_NOT_EMPTY"
+  | "DATA_ROOT_MOVE_IN_PROGRESS"
+  | "DATA_ROOT_COPY_FAILED"
+  // The copy did not match the source, so nothing was deleted. Its own code
+  // rather than a copy failure: the user's data is still where it was, and
+  // saying so is the whole point of verifying before deleting.
+  | "DATA_ROOT_VERIFY_FAILED"
+  // Synchronised windows.
+  | "SYNC_SESSION_NOT_FOUND"
+  | "SYNC_FOLLOWER_NOT_FOUND"
+  | "SYNC_SESSION_UNAVAILABLE"
+  | "SYNC_DISPLAY_UNAVAILABLE"
+  | "SYNC_DISPLAY_TOO_SMALL"
+  | "SYNC_ARRANGE_FAILED"
   | "INTERNAL_ERROR";
 
 export interface BackendError {
@@ -188,6 +290,25 @@ export function parseBackendError(err: unknown): BackendError | null {
  * Translate a backend error to a localized string. Falls back to the raw
  * message if the error isn't a structured backend error.
  */
+/**
+ * A leased-host operating system as a person reads it.
+ *
+ * macOS / Windows / Linux are proper nouns, the same in every locale, so they
+ * are not translated — only mapped from the wire value the fleet uses.
+ */
+function remoteOsLabel(platform: string): string {
+  switch (platform) {
+    case "macos":
+      return "macOS";
+    case "windows":
+      return "Windows";
+    case "linux":
+      return "Linux";
+    default:
+      return platform;
+  }
+}
+
 export function translateBackendError(t: TFunction, err: unknown): string {
   const parsed = parseBackendError(err);
   if (!parsed) {
@@ -208,8 +329,19 @@ export function translateBackendError(t: TFunction, err: unknown): string {
       return t("backendErrors.profileNotProtected");
     case "PROFILE_ALREADY_PROTECTED":
       return t("backendErrors.profileAlreadyProtected");
+    case "TOOL_IS_LOCAL_ONLY":
+      return t("backendErrors.toolIsLocalOnly");
+    case "TYPING_TOO_LONG":
+      return t("backendErrors.typingTooLong", {
+        seconds: parsed.params?.seconds ?? "",
+        limit: parsed.params?.limit ?? "",
+      });
+    case "URL_SCHEME_NOT_ALLOWED":
+      return t("backendErrors.urlSchemeNotAllowed");
     case "PROFILE_RUNNING":
       return t("backendErrors.profileRunning");
+    case "PROFILE_PAIRED_TWICE":
+      return t("backendErrors.profilePairedTwice");
     case "PROFILE_EPHEMERAL":
       return t("backendErrors.profileEphemeral");
     case "PROFILE_MISSING_SALT":
@@ -275,6 +407,14 @@ export function translateBackendError(t: TFunction, err: unknown): string {
       return t("backendErrors.extensionLinkRequiresDirectory");
     case "EXTENSION_LINKED_CANNOT_SYNC":
       return t("backendErrors.extensionLinkedCannotSync");
+    case "EXTENSION_URL_INVALID":
+      return t("backendErrors.extensionUrlInvalid");
+    case "EXTENSION_DOWNLOAD_FAILED":
+      return t("backendErrors.extensionDownloadFailed");
+    case "EXTENSION_NOT_AN_EXTENSION":
+      return t("backendErrors.extensionNotAnExtension");
+    case "EXTENSION_TOO_LARGE":
+      return t("backendErrors.extensionTooLarge");
     case "CANNOT_MODIFY_CLOUD_MANAGED_PROXY":
       return t("backendErrors.cannotModifyCloudManagedProxy");
     case "SYNC_LOCKED_BY_PROFILE":
@@ -287,6 +427,10 @@ export function translateBackendError(t: TFunction, err: unknown): string {
       return t("backendErrors.proxyNotWorking");
     case "PROXY_PAYMENT_REQUIRED":
       return t("backendErrors.proxyPaymentRequired");
+    case "PROXY_TLS_HANDSHAKE_FAILED":
+      return t("backendErrors.proxyTlsHandshakeFailed", {
+        proxy: parsed.params?.proxy ?? "",
+      });
     case "VPN_NOT_WORKING":
       return t("backendErrors.vpnNotWorking");
     case "CAMOUFOX_IMPORT_DEPRECATED":
@@ -369,6 +513,24 @@ export function translateBackendError(t: TFunction, err: unknown): string {
       return t("backendErrors.mcpPortUnavailable");
     case "MCP_CONFIGURATION_UNAVAILABLE":
       return t("backendErrors.mcpConfigurationUnavailable");
+    case "MCP_REMOTE_REQUIRES_SIGN_IN":
+      return t("backendErrors.mcpRemoteRequiresSignIn");
+    case "MCP_REMOTE_UNAUTHORIZED":
+      return t("backendErrors.mcpRemoteUnauthorized");
+    case "MCP_REMOTE_SLOT_TAKEN":
+      return t("backendErrors.mcpRemoteSlotTaken");
+    case "MCP_REMOTE_NOT_ENTITLED":
+      return t("backendErrors.mcpRemoteNotEntitled");
+    case "MCP_REMOTE_UNREACHABLE":
+      return t("backendErrors.mcpRemoteUnreachable");
+    case "MCP_REMOTE_KEY_MISSING":
+      return t("backendErrors.mcpRemoteKeyMissing");
+    case "MCP_REMOTE_KEY_LIMIT":
+      return t("backendErrors.mcpRemoteKeyLimit");
+    case "MCP_REMOTE_KEY_UNAVAILABLE":
+      return t("backendErrors.mcpRemoteKeyUnavailable");
+    case "MCP_LOCAL_REMOVED":
+      return t("backendErrors.mcpLocalRemoved");
     case "MCP_AGENT_UNKNOWN":
       return t("backendErrors.mcpAgentUnknown");
     case "MCP_AGENT_INSTALL_FAILED":
@@ -418,8 +580,41 @@ export function translateBackendError(t: TFunction, err: unknown): string {
       return t("backendErrors.cloudRequestFailed");
     case "REMOTE_RATE_LIMITED":
       return t("backendErrors.remoteRateLimited");
-    case "REMOTE_NO_CAPACITY":
-      return t("backendErrors.remoteNoCapacity");
+    case "REMOTE_NO_CAPACITY": {
+      // Newer backends name the platform; older ones (and a bare 503 mapped by
+      // status alone) do not, so fall back to the platform-free line.
+      const platform = parsed.params?.platform;
+      return platform
+        ? t("backendErrors.remoteNoCapacityPlatform", {
+            platform: remoteOsLabel(platform),
+          })
+        : t("backendErrors.remoteNoCapacity");
+    }
+    case "REMOTE_NOT_CONFIGURED":
+      return t("backendErrors.remoteNotConfigured");
+    case "REMOTE_LAUNCH_REFUSED": {
+      // The server's own words, when it gave any. Kept as a diagnostic; the
+      // generic line stands alone when it did not.
+      const detail = parsed.params?.detail?.trim();
+      return detail
+        ? t("backendErrors.remoteLaunchRefusedDetail", { detail })
+        : t("backendErrors.remoteLaunchRefused");
+    }
+    case "REMOTE_FLEET_UNREACHABLE":
+      return t("backendErrors.remoteFleetUnreachable");
+    case "REMOTE_CONCURRENCY_LIMIT":
+      return t("backendErrors.remoteConcurrencyLimit", {
+        live: parsed.params?.live ?? "",
+        limit: parsed.params?.limit ?? "",
+      });
+    case "REMOTE_SESSION_NOT_DRIVABLE":
+      return t("backendErrors.remoteSessionNotDrivable");
+    case "REMOTE_PLATFORM_UNSUPPORTED":
+      return t("backendErrors.remotePlatformUnsupported", {
+        platform: remoteOsLabel(parsed.params?.platform ?? ""),
+      });
+    case "REMOTE_PROFILE_NOT_SYNCED":
+      return t("backendErrors.remoteProfileNotSynced");
     case "REMOTE_NOT_ENTITLED":
       return t("backendErrors.remoteNotEntitled");
     // Distinct from the above: the plan HAS remote hours, it just may not spend
@@ -430,6 +625,10 @@ export function translateBackendError(t: TFunction, err: unknown): string {
       return t("backendErrors.remoteInteractiveNotEntitled");
     case "REMOTE_REQUIRES_REMOTE_EXIT_NODE":
       return t("backendErrors.remoteRequiresRemoteExitNode");
+    case "REMOTE_PROXY_KIND_UNSUPPORTED":
+      return t("backendErrors.remoteProxyKindUnsupported", {
+        kind: parsed.params?.kind ?? "",
+      });
     case "REMOTE_SESSION_REFUSED":
       return t("backendErrors.remoteSessionRefused");
     case "REMOTE_SESSION_NOT_FOUND":
@@ -504,8 +703,38 @@ export function translateBackendError(t: TFunction, err: unknown): string {
       return t("backendErrors.cookieBotRequiresExitNode");
     case "COOKIE_BOT_REQUIRES_REMOTE_EXIT_NODE":
       return t("backendErrors.cookieBotRequiresRemoteExitNode");
+    case "COOKIE_BOT_PROXY_KIND_UNSUPPORTED":
+      return t("backendErrors.cookieBotProxyKindUnsupported", {
+        kind: parsed.params?.kind ?? "",
+      });
     case "COOKIE_BOT_TOUCH_FINGERPRINT_UNSUPPORTED":
       return t("backendErrors.cookieBotTouchFingerprintUnsupported");
+    case "AGENT_NOT_ENTITLED":
+      return t("backendErrors.agentNotEntitled");
+    case "AGENT_NOT_CONFIGURED":
+      return t("backendErrors.agentNotConfigured");
+    case "AGENT_TARGET_OFFLINE":
+      return t("backendErrors.agentTargetOffline");
+    case "AGENT_BUDGET_EXCEEDED":
+      return t("backendErrors.agentBudgetExceeded");
+    case "AGENT_RUN_LIMIT_REACHED":
+      return t("backendErrors.agentRunLimitReached");
+    case "AGENT_RUN_NOT_FOUND":
+      return t("backendErrors.agentRunNotFound");
+    case "AGENT_RUN_NOT_CANCELLABLE":
+      return t("backendErrors.agentRunNotCancellable");
+    case "AGENT_GOAL_INVALID":
+      return t("backendErrors.agentGoalInvalid");
+    case "AGENT_BUDGET_INVALID":
+      return t("backendErrors.agentBudgetInvalid");
+    // The run was started against a profile the issued token does not cover.
+    // Its own code because signing in again is the fix, not editing the goal.
+    case "AGENT_TOKEN_PROFILE_MISMATCH":
+      return t("backendErrors.agentTokenProfileMismatch");
+    case "AGENT_RECIPE_INVALID":
+      return t("backendErrors.agentRecipeInvalid");
+    case "AGENT_RECIPE_NOT_FOUND":
+      return t("backendErrors.agentRecipeNotFound");
     // The launch gate's block. The dialog renders the mismatch detail from
     // `params` itself; this string is the fallback for anywhere that only has
     // room for one sentence.
@@ -525,6 +754,34 @@ export function translateBackendError(t: TFunction, err: unknown): string {
       return t("backendErrors.wayfernCrossOsRequiresPlan", {
         detail: parsed.params?.detail ?? "",
       });
+    case "WAYFERN_IDENTITY_REFUSED":
+      return t("backendErrors.wayfernIdentityRefused", {
+        detail: parsed.params?.detail ?? "",
+      });
+    case "PROFILE_EXPORT_FAILED":
+      return t("backendErrors.profileExportFailed", {
+        detail: parsed.params?.detail ?? "",
+      });
+    case "PROFILE_EXPORT_TOO_LARGE":
+      return t("backendErrors.profileExportTooLarge");
+    case "PROFILE_IMPORT_FAILED":
+      return t("backendErrors.profileImportFailed", {
+        detail: parsed.params?.detail ?? "",
+      });
+    case "PROFILE_IMPORT_TOO_NEW":
+      return t("backendErrors.profileImportTooNew");
+    case "PROFILE_IMPORT_UNSAFE_ARCHIVE":
+      return t("backendErrors.profileImportUnsafeArchive");
+    case "RECORDING_ALREADY_RUNNING":
+      return t("backendErrors.recordingAlreadyRunning");
+    case "PROFILE_NOT_RUNNING":
+      return t("backendErrors.profileNotRunning");
+    case "WAYFERN_152_REQUIRED":
+      return t("backendErrors.wayfern152Required");
+    case "RECORDING_FAILED":
+      return t("backendErrors.recordingFailed", {
+        detail: parsed.params?.detail ?? "",
+      });
     case "LAUNCH_CONSENT_EXPIRED":
       return t("backendErrors.launchConsentExpired");
     case "VPN_WORKER_START_FAILED":
@@ -537,6 +794,52 @@ export function translateBackendError(t: TFunction, err: unknown): string {
       return t("backendErrors.camoufoxRemoved");
     case "NO_E2E_PASSWORD_SET":
       return t("backendErrors.noE2ePasswordSet");
+    case "TRASH_ENTRY_NOT_FOUND":
+      return t("backendErrors.trashEntryNotFound");
+    case "TRASH_RESTORE_CONFLICT":
+      return t("backendErrors.trashRestoreConflict");
+    case "DATA_ROOT_SAME_AS_CURRENT":
+      return t("backendErrors.dataRootSameAsCurrent");
+    case "DATA_ROOT_DESTINATION_INSIDE_SOURCE":
+      return t("backendErrors.dataRootDestinationInsideSource");
+    case "DATA_ROOT_BROWSER_RUNNING":
+      return t("backendErrors.dataRootBrowserRunning");
+    case "DATA_ROOT_SYNC_IN_PROGRESS":
+      return t("backendErrors.dataRootSyncInProgress");
+    // The figures arrive already written out. This module is imported by a
+    // plain `node --test` run, so it stays free of project imports, and the
+    // one place that knows the byte counts formats them.
+    case "DATA_ROOT_INSUFFICIENT_SPACE":
+      return t("backendErrors.dataRootInsufficientSpace", {
+        required: parsed.params?.required ?? "",
+        available: parsed.params?.available ?? "",
+      });
+    case "DATA_ROOT_DESTINATION_NOT_WRITABLE":
+      return t("backendErrors.dataRootDestinationNotWritable");
+    case "DATA_ROOT_DESTINATION_NOT_EMPTY":
+      return t("backendErrors.dataRootDestinationNotEmpty");
+    case "DATA_ROOT_MOVE_IN_PROGRESS":
+      return t("backendErrors.dataRootMoveInProgress");
+    case "DATA_ROOT_COPY_FAILED":
+      return t("backendErrors.dataRootCopyFailed", {
+        detail: parsed.params?.detail ?? "",
+      });
+    case "DATA_ROOT_VERIFY_FAILED":
+      return t("backendErrors.dataRootVerifyFailed");
+    case "SYNC_SESSION_NOT_FOUND":
+      return t("backendErrors.syncSessionNotFound");
+    case "SYNC_FOLLOWER_NOT_FOUND":
+      return t("backendErrors.syncFollowerNotFound");
+    case "SYNC_SESSION_UNAVAILABLE":
+      return t("backendErrors.syncSessionUnavailable");
+    case "SYNC_DISPLAY_UNAVAILABLE":
+      return t("backendErrors.syncDisplayUnavailable");
+    case "SYNC_DISPLAY_TOO_SMALL":
+      return t("backendErrors.syncDisplayTooSmall", {
+        windows: Number(parsed.params?.count ?? 0),
+      });
+    case "SYNC_ARRANGE_FAILED":
+      return t("backendErrors.syncArrangeFailed");
     case "INTERNAL_ERROR":
       return t("backendErrors.internal", {
         detail: parsed.params?.detail ?? "",