fix(downloads): harden queue admission and live speed controls

src/components/PropertiesModal.tsx

@@ -72,6 +72,8 @@ export const PropertiesModal = () => {
   
   const [speedLimitEnabled, setSpeedLimitEnabled] = useState(false);
   const [speedLimitValue, setSpeedLimitValue] = useState('1024'); // KiB/s
+  const [liveSpeedLimitValue, setLiveSpeedLimitValue] = useState('');
+  const [isLiveSpeedLimitPending, setIsLiveSpeedLimitPending] = useState(false);
 
   const [loginMode, setLoginMode] = useState<LoginMode>('matching');
   const [username, setUsername] = useState('');
@@ -143,6 +145,11 @@ export const PropertiesModal = () => {
     }
   }, [selectedPropertiesDownloadId, setSelectedPropertiesDownloadId]);
 
+  useEffect(() => {
+    const activeLimit = item?.speedLimit?.trim();
+    setLiveSpeedLimitValue(activeLimit && activeLimit !== '0' ? activeLimit : '');
+  }, [item?.speedLimit, selectedPropertiesDownloadId]);
+
   useEffect(() => {
     if (!selectedPropertiesDownloadId || connectionsDirty) return;
     const activeItem = useDownloadStore.getState().downloads.find(d => d.id === selectedPropertiesDownloadId);
@@ -245,8 +252,27 @@ export const PropertiesModal = () => {
     }
   };
 
+  const handleLiveSpeedLimit = async (limit: string | null) => {
+    if (isLiveSpeedLimitPending || item.isMedia || !['downloading', 'retrying'].includes(item.status)) return;
+
+    setErrorMessage('');
+    setIsLiveSpeedLimitPending(true);
+    try {
+      await useDownloadStore.getState().setDownloadSpeedLimit(item.id, limit);
+      if (limit === null) setLiveSpeedLimitValue('');
+    } catch (error) {
+      setErrorMessage(t($ => $.properties.liveSpeedLimitFailed, {
+        detail: error instanceof Error ? error.message : String(error)
+      }));
+    } finally {
+      setIsLiveSpeedLimitPending(false);
+    }
+  };
+
   const identityLocked = getIdentityLocked(item.status);
   const transferLocked = getTransferLocked(item.status);
+  const liveSpeedLimitAvailable = !item.isMedia && ['downloading', 'retrying'].includes(item.status);
+  const liveSpeedLimitUnavailable = item.isMedia && ['downloading', 'processing', 'retrying'].includes(item.status);
   const configuredConnections = resolveDownloadConnections(item.connections, perServerConnections);
   const observedConnectionTotal = Math.max(
     1,
@@ -458,6 +484,53 @@ export const PropertiesModal = () => {
                   </div>
                 )}
               </div>
+              {(liveSpeedLimitAvailable || liveSpeedLimitUnavailable) && (
+                <div className="col-start-2 rounded-md border border-border-modal/60 bg-border-color/20 p-3 space-y-2">
+                  {liveSpeedLimitAvailable ? (
+                    <>
+                      <label htmlFor="live-speed-limit" className="block text-xs font-medium text-text-primary">
+                        {t($ => $.properties.liveSpeedLimit)}
+                      </label>
+                      <div className="flex items-center gap-2">
+                        <input
+                          id="live-speed-limit"
+                          type="text"
+                          inputMode="decimal"
+                          value={liveSpeedLimitValue}
+                          onChange={event => setLiveSpeedLimitValue(event.currentTarget.value)}
+                          placeholder={t($ => $.properties.liveSpeedLimitPlaceholder)}
+                          disabled={isLiveSpeedLimitPending}
+                          aria-describedby="live-speed-limit-hint"
+                          className="w-28 bg-bg-input border border-border-modal rounded-lg px-2.5 py-1.5 text-xs text-text-primary focus:outline-none focus:border-accent disabled:opacity-50"
+                        />
+                        <button
+                          type="button"
+                          onClick={() => void handleLiveSpeedLimit(liveSpeedLimitValue)}
+                          disabled={isLiveSpeedLimitPending}
+                          className="app-button app-button-primary px-3 text-xs disabled:opacity-50"
+                        >
+                          {t($ => $.properties.liveSpeedLimitApply)}
+                        </button>
+                        <button
+                          type="button"
+                          onClick={() => void handleLiveSpeedLimit(null)}
+                          disabled={isLiveSpeedLimitPending || !liveSpeedLimitValue}
+                          className="app-button px-3 text-xs disabled:opacity-50"
+                        >
+                          {t($ => $.properties.liveSpeedLimitClear)}
+                        </button>
+                      </div>
+                      <p id="live-speed-limit-hint" className="text-[11px] text-text-muted">
+                        {t($ => $.properties.liveSpeedLimitHint)}
+                      </p>
+                    </>
+                  ) : (
+                    <p className="text-[11px] text-text-muted">
+                      {t($ => $.properties.liveSpeedLimitUnavailable)}
+                    </p>
+                  )}
+                </div>
+              )}
             </div>
           </section>
 

src/components/Sidebar.tsx

@@ -22,7 +22,7 @@ interface SidebarProps {
 
 export const Sidebar: React.FC<SidebarProps> = (props) => {
   const { selectedFilter, onSelectFilter } = props;
-  const { downloads, queues, addQueue, renameQueue, removeQueue, startQueue, pauseQueue } = useDownloadStore();
+  const { downloads, queues, addQueue, renameQueue, removeQueue, startQueue, pauseQueue, setQueueConcurrency } = useDownloadStore();
   const { activeView, setActiveView, toggleSidebar } = useSettingsStore();
   const { addToast } = useToast();
   const { t } = useTranslation();
@@ -475,6 +475,45 @@ export const Sidebar: React.FC<SidebarProps> = (props) => {
             <Pause size={14} className="me-2 text-text-secondary" />
             {t($ => $.actions.pauseQueue)}
           </button>
+          {(() => {
+            const queue = queues.find(candidate => candidate.id === contextMenu.id);
+            if (!queue) return null;
+            return (
+              <div
+                role="group"
+                aria-labelledby="queue-concurrency-label"
+                className="px-3 py-2 text-[12px] text-text-secondary"
+                onClick={event => event.stopPropagation()}
+              >
+                <label id="queue-concurrency-label" htmlFor="queue-concurrency-select" className="block mb-1">
+                  {t($ => $.sidebar.queueConcurrency)}
+                </label>
+                <select
+                  id="queue-concurrency-select"
+                  aria-label={t($ => $.sidebar.queueConcurrency)}
+                  value={queue.maxConcurrent?.toString() ?? ''}
+                  className="w-full rounded border border-border-color bg-bg-context-menu px-1.5 py-1 text-[12px] text-text-primary outline-none focus:border-accent"
+                  onChange={event => {
+                    const value = event.currentTarget.value === ''
+                      ? null
+                      : Number(event.currentTarget.value);
+                    void setQueueConcurrency(queue.id, value).catch(error => {
+                      addToast({
+                        message: t($ => $.sidebar.queueConcurrencyFailed, { detail: String(error) }),
+                        variant: 'error',
+                        isActionable: true
+                      });
+                    });
+                  }}
+                >
+                  <option value="">{t($ => $.sidebar.queueConcurrencyGlobal)}</option>
+                  {Array.from({ length: 12 }, (_, index) => index + 1).map(value => (
+                    <option key={value} value={value}>{value}</option>
+                  ))}
+                </select>
+              </div>
+            );
+          })()}
           <div className="h-px bg-border-color my-1 mx-2" />
           <button
             className="w-full text-start px-3 py-1.5 flex items-center hover:bg-item-hover"