fix(ui): single-flight scan poll so status line does not alternate

Made-with: Cursor

internal/webui/index.html

@@ -249,6 +249,8 @@
       /** @type {{if_index:number,bridge_port:number,mac:string,learned_ip:string}[]} */
       let lastPortDevItems = [];
       let selectedFdbKey = null;
+      /** Увеличивается при каждом новом pollScanUntilDone — снимает гонку createScan vs watchScan (чередование строк статуса). */
+      let scanPollSeq = 0;
 
       const sleep = (ms) => new Promise((r) => setTimeout(r, ms));
 
@@ -287,31 +289,47 @@
        * @param {{ intervalMs?: number, maxWaitMs?: number, onDone?: function }} opts
        */
       async function pollScanUntilDone(scanId, opts = {}) {
+        const mySeq = ++scanPollSeq;
         const intervalMs = opts.intervalMs ?? 1000;
         const maxWaitMs = opts.maxWaitMs ?? 20 * 60 * 1000;
         const started = Date.now();
         while (Date.now() - started < maxWaitMs) {
+          if (mySeq !== scanPollSeq) {
+            return null;
+          }
           let job;
           try {
             job = await fetchScanJob(scanId);
           } catch (e) {
+            if (mySeq === scanPollSeq) {
               setStatus(`Ошибка опроса скана: ${e.message}`);
+            }
+            return null;
+          }
+          if (mySeq !== scanPollSeq) {
             return null;
           }
           setStatus(describeScanProgress(job));
           if (job.status === "done" || job.status === "failed" || job.status === "canceled") {
+            if (mySeq !== scanPollSeq) {
+              return null;
+            }
             if (opts.onDone) {
               try {
                 await opts.onDone(job);
               } catch (e) {
+                if (mySeq === scanPollSeq) {
                   setStatus((statusEl.textContent || "") + ` | Ошибка в onDone: ${e.message}`);
                 }
               }
+            }
             return job;
           }
           await sleep(intervalMs);
         }
+        if (mySeq === scanPollSeq) {
           setStatus(`Таймаут ожидания скана ${scanId} (${Math.round(maxWaitMs / 60000)} мин).`);
+        }
         return null;
       }