fix(design): preserve command outcome certainty

src/lib/host-api.ts

@@ -112,14 +112,23 @@ async function parseResponse<T>(response: Response): Promise<T> {
   if (!response.ok) {
     let message = `${response.status} ${response.statusText}`;
     let backendCode: string | undefined;
+    let commandOutcome: string | undefined;
     try {
-      const payload = await response.json() as { error?: string; code?: unknown };
+      const payload = await response.json() as {
+        error?: string;
+        code?: unknown;
+        commandOutcome?: unknown;
+      };
       if (payload?.error) {
         message = payload.error;
       }
       if (typeof payload?.code === 'string' && /^[a-z][a-z0-9_]{0,63}$/u.test(payload.code)) {
         backendCode = payload.code;
       }
+      if (payload?.commandOutcome === 'definitive_failure'
+        || payload?.commandOutcome === 'unknown') {
+        commandOutcome = payload.commandOutcome;
+      }
     } catch {
       // ignore body parse failure
     }
@@ -127,6 +136,7 @@ async function parseResponse<T>(response: Response): Promise<T> {
       source: 'browser-fallback',
       status: response.status,
       ...(backendCode ? { backendCode } : {}),
+      ...(commandOutcome ? { commandOutcome } : {}),
     });
   }
 
@@ -155,6 +165,9 @@ function createProxyHttpError(data: HostApiProxyData): Error {
   return normalizeAppError(new Error(message), {
     status: data.status,
     ...(payload && typeof payload.code === 'string' ? { backendCode: payload.code } : {}),
+    ...(payload?.commandOutcome === 'definitive_failure' || payload?.commandOutcome === 'unknown'
+      ? { commandOutcome: payload.commandOutcome }
+      : {}),
   });
 }