fix: keep session when refresh fails on network error or 5xx (WealthLedger/frontend#97)

src/shared/api/client.ts

@@ -32,6 +32,10 @@ type AuthHandlers = {
 	clear: () => void;
 	generation?: () => number;
 	refresh: () => Promise<boolean>;
+	/**
+	True after a refresh failed transiently (network/5xx): the session is not proven gone.
+	*/
+	unavailable?: () => boolean;
 };
 
 type ReadAttempt = {
@@ -100,7 +104,8 @@ async function authenticatedFetch(request: Request): Promise<Response> {
 	if (!isCurrent()) throw new DOMException("Session changed", "AbortError");
 
 	if (!(await sessionState.handlers.refresh())) {
-		if (isCurrent()) sessionState.handlers.clear();
+		if (isCurrent() && !sessionState.handlers.unavailable?.())
+			sessionState.handlers.clear();
 
 		return response;
 	}