HTTP 416: erschoepftes Range-Konflikt-Item macht bounded Clean-Restart statt dauerhaft zu haengen

Nutzer-Report (ultracode-Diagnose, 6-Agenten): ein Item mit "Fehler: HTTP 416"
(Range Not Satisfiable) wurde gar nicht mehr erneut versucht und blockierte das
ganze Paket ("Entpacken - Ausstehend" bei allen fertigen Geschwistern). Befund
code-belegt: nach dem In-Run-416-Budget (maxHttp416Retries) lief das Item in
einen Endzustand:
- retryLimit>0 (bare "HTTP 416", directLinkRetryMatch=false): direkt terminal
  "failed" (download-manager ~9442). Der einzige Re-Retry-Pfad
  recoverRetryableItems() laeuft NUR bei Boot/Start, nie mid-run -> mit
  autoReconnect=false bleibt es bis zum Neustart "failed". Und da jeder
  Extract-Zweig auf failed===0 gated, friert EIN failed-Item das ganze Paket
  ein -> exakt das Screenshot-Symptom.
- retryLimit=0 (wrapped "direct_link_retry_exhausted:HTTP 416"): faellt nach dem
  416-Budget in den generischen Retry (9349) mit maxGenericErrorRetries=
  MAX_SAFE_INTEGER -> unbegrenzte futile Re-Unrestricts (haemmert den Hoster,
  Item kommt nie weiter).

Fix: bei erschoepftem 416-Budget an BEIDEN Stellen (gewrappt @9320, bare @9442)
nicht mehr terminalisieren bzw. endlos generisch retrien, sondern via neuem
escalateHttp416OrFail() einen kompletten Neu-Download von 0 anstossen: Partial
loeschen (rmSync), Bytes/Progress/Budget zuruecksetzen, mit Delay re-queuen. Da
416 ein abgelehnter Resume-Range ist, ist der korrekte Weg ein frischer
Download ohne Range-Header (kein 416 mehr) statt erneuter Resume. Hart gedeckelt
ueber http416FreshRestartByItem (MAX_HTTP416_FRESH_RESTARTS=2, retryLimit-
unabhaengig) -> ein wirklich toter Link faellt nach begrenzten sauberen
Neustarts terminal, kein Endlos-Hammering. Zaehler wird in start() und beim
terminalen Fail geleert. Fresh-Restart-Delay via RD_HTTP416_FRESH_RESTART_DELAY_MS
testbar.

Sobald das Item den failed-Zustand verlaesst, entsperrt die bestehende
failed===0-Logik das Paket-Entpacken von selbst. (Die optionale Haertung
"fertige Archiv-Sets trotz failed-Geschwister entpacken" + "Voll-Datei-416 als
fertig werten statt neu laden" sind bewusst als Folgeschritt offen.)

Tests: Recovery (416 erschoepft -> Clean-Restart -> Item completed, retryLimit>0
bare) + Bounded-Fail (persistentes 416 -> begrenzte Neustarts -> failed,
retryLimit=0 wrapped, terminiert statt Endlos). Suite 945 gruen, tsc=6.

src/main/download-manager.ts

@@ -131,6 +131,17 @@ const ARCHIVE_SETTLE_MAX_WAIT_MS = 5000;
 
 const MAX_SAME_DIRECT_URL_ATTEMPTS = 3;
 
+const MAX_HTTP416_FRESH_RESTARTS = 2;
+const HTTP416_FRESH_RESTART_DELAY_MS = 8000;
+
+function getHttp416FreshRestartDelayMs(): number {
+  const fromEnv = Number(process.env.RD_HTTP416_FRESH_RESTART_DELAY_MS ?? NaN);
+  if (Number.isFinite(fromEnv) && fromEnv >= 0 && fromEnv <= 600000) {
+    return Math.floor(fromEnv);
+  }
+  return HTTP416_FRESH_RESTART_DELAY_MS;
+}
+
 const RESUME_REWIND_BYTES = 256 * 1024;
 
 const REALDEBRID_TOTAL_MISMATCH_TOLERANCE_BYTES = 64 * 1024;
@@ -1829,6 +1840,8 @@ export class DownloadManager extends EventEmitter {
     unrestrictRetries: number;
   }>();
 
+  private http416FreshRestartByItem = new Map<string, number>();
+
   private providerFailures = new Map<string, { count: number; lastFailAt: number; cooldownUntil: number }>();
 
   private allDebridHostInfoCache = new Map<string, { info: AllDebridHostInfo; cachedAt: number }>();
@@ -5678,6 +5691,7 @@ export class DownloadManager extends EventEmitter {
     this.providerStartReservations.clear();
     this.pacedStartReservationByItem.clear();
     this.retryStateByItem.clear();
+    this.http416FreshRestartByItem.clear();
     this.itemContributedBytes.clear();
     this.reservedTargetPaths.clear();
     this.claimedTargetPathByItem.clear();
@@ -8727,6 +8741,53 @@ export class DownloadManager extends EventEmitter {
     this.queueRetry(item, active, delayMs, `HTTP 416 erkannt, Retry ${active.genericErrorRetries}/${retryDisplayLimit}`);
   }
 
+  private escalateHttp416OrFail(item: DownloadItem, active: ActiveTask, claimedTargetPath: string, errorText: string): void {
+    const freshRestarts = this.http416FreshRestartByItem.get(item.id) || 0;
+    if (freshRestarts < MAX_HTTP416_FRESH_RESTARTS) {
+      this.http416FreshRestartByItem.set(item.id, freshRestarts + 1);
+      const resetTargetPath = claimedTargetPath || String(item.targetPath || "").trim();
+      if (resetTargetPath) {
+        try {
+          fs.rmSync(resetTargetPath, { force: true });
+        } catch {
+        }
+      }
+      this.releaseTargetPath(item.id);
+      this.dropItemContribution(item.id);
+      item.retries += 1;
+      item.downloadedBytes = 0;
+      item.totalBytes = null;
+      item.progressPercent = 0;
+      item.speedBps = 0;
+      item.lastError = "";
+      active.genericErrorRetries = 0;
+      active.freshRetryUsed = false;
+      active.resumeHardResetUsed = false;
+      logger.warn(
+        `HTTP 416 Budget erschöpft: item=${item.fileName || item.id}, ` +
+        `kompletter Neu-Download ${freshRestarts + 1}/${MAX_HTTP416_FRESH_RESTARTS} (Partial verworfen, kein Resume), provider=${item.provider || "?"}`
+      );
+      this.queueRetry(item, active, getHttp416FreshRestartDelayMs(), `Range-Konflikt (HTTP 416): Neu-Download ${freshRestarts + 1}/${MAX_HTTP416_FRESH_RESTARTS}`);
+      this.persistSoon();
+      this.emitState();
+      return;
+    }
+    this.http416FreshRestartByItem.delete(item.id);
+    item.status = "failed";
+    this.recordRunOutcome(item.id, "failed");
+    item.lastError = errorText;
+    item.fullStatus = `Fehler: ${item.lastError}`;
+    item.speedBps = 0;
+    item.updatedAt = nowMs();
+    const failPkg = this.session.packages[item.packageId];
+    if (failPkg) {
+      this.refreshPackageStatus(failPkg);
+    }
+    this.persistSoon();
+    this.emitState();
+    this.retryStateByItem.delete(item.id);
+  }
+
   private startItem(packageId: string, itemId: string): void {
     const item = this.session.items[itemId];
     const pkg = this.session.packages[packageId];
@@ -9317,10 +9378,14 @@ export class DownloadManager extends EventEmitter {
                 return;
               }
             }
-            if (isHttp416Text(exhaustedReason) && active.genericErrorRetries < maxHttp416Retries) {
+            if (isHttp416Text(exhaustedReason)) {
-              this.scheduleHttp416Retry(item, active, retryDisplayLimit, exhaustedReason, claimedTargetPath);
+              if (active.genericErrorRetries < maxHttp416Retries) {
-              this.persistSoon();
+                this.scheduleHttp416Retry(item, active, retryDisplayLimit, exhaustedReason, claimedTargetPath);
-              this.emitState();
+                this.persistSoon();
+                this.emitState();
+                return;
+              }
+              this.escalateHttp416OrFail(item, active, claimedTargetPath, exhaustedReason);
               return;
             }
             if (isResumeHardResetReason(exhaustedReason) && !active.resumeHardResetUsed) {
@@ -9377,17 +9442,7 @@ export class DownloadManager extends EventEmitter {
               this.emitState();
               return;
             }
-            item.status = "failed";
+            this.escalateHttp416OrFail(item, active, claimedTargetPath, errorText);
-            this.recordRunOutcome(item.id, "failed");
-            item.lastError = errorText;
-            item.fullStatus = `Fehler: ${item.lastError}`;
-            item.speedBps = 0;
-            item.updatedAt = nowMs();
-            const failPkg416 = this.session.packages[item.packageId];
-            if (failPkg416) this.refreshPackageStatus(failPkg416);
-            this.persistSoon();
-            this.emitState();
-            this.retryStateByItem.delete(item.id);
             return;
           }
           if (shouldFreshRetry) {

tests/download-manager.test.ts

@@ -2209,6 +2209,98 @@ describe("download manager", () => {
     expect(fs.statSync(item.targetPath).size).toBe(binary.length);
   });
 
+  it("recovers an HTTP 416 item with a clean fresh restart after the in-budget retries are exhausted", async () => {
+    const root = fs.mkdtempSync(path.join(os.tmpdir(), "rd-416-fresh-"));
+    tempDirs.push(root);
+    const binary = Buffer.alloc(160 * 1024, 19);
+    const prevDelay = process.env.RD_HTTP416_FRESH_RESTART_DELAY_MS;
+    process.env.RD_HTTP416_FRESH_RESTART_DELAY_MS = "0";
+    let downloadCalls = 0;
+
+    globalThis.fetch = async (input: RequestInfo | URL): Promise<Response> => {
+      const url = typeof input === "string" ? input : input instanceof URL ? input.toString() : input.url;
+      if (url.includes("/unrestrict/link")) {
+        return new Response(JSON.stringify({ download: "https://dummy/direct-416-recover", filename: "fresh-416.mkv", filesize: binary.length }), { status: 200, headers: { "Content-Type": "application/json" } });
+      }
+      throw new Error(`unexpected fetch ${url}`);
+    };
+
+    try {
+      const manager = new DownloadManager(
+        { ...defaultSettings(), token: "rd-token", outputDir: path.join(root, "downloads"), extractDir: path.join(root, "extract"), retryLimit: 2, autoExtract: false, autoReconnect: false },
+        emptySession(),
+        createStoragePaths(path.join(root, "state"))
+      );
+
+      (manager as any).downloadToFile = async (_active: unknown, _directUrl: string, targetPath: string) => {
+        downloadCalls += 1;
+        if (downloadCalls <= 3) {
+          throw new Error("HTTP 416");
+        }
+        fs.mkdirSync(path.dirname(targetPath), { recursive: true });
+        fs.writeFileSync(targetPath, binary);
+        const item = Object.values((manager as any).session.items)[0] as { downloadedBytes: number; totalBytes: number; progressPercent: number } | undefined;
+        if (item) {
+          item.downloadedBytes = binary.length;
+          item.totalBytes = binary.length;
+          item.progressPercent = 100;
+        }
+        return { resumable: true };
+      };
+
+      manager.addPackages([{ name: "fresh-416", links: ["https://dummy/fresh-416"] }]);
+      await manager.start();
+      await waitFor(() => !manager.getSnapshot().session.running, 20000);
+
+      const item = Object.values(manager.getSnapshot().session.items)[0];
+      expect(item?.status).toBe("completed");
+      expect(downloadCalls).toBeGreaterThan(3);
+    } finally {
+      if (prevDelay === undefined) { delete process.env.RD_HTTP416_FRESH_RESTART_DELAY_MS; } else { process.env.RD_HTTP416_FRESH_RESTART_DELAY_MS = prevDelay; }
+    }
+  }, 25000);
+
+  it("bounds HTTP 416 clean restarts and finally fails instead of looping forever or stalling permanently", async () => {
+    const root = fs.mkdtempSync(path.join(os.tmpdir(), "rd-416-cap-"));
+    tempDirs.push(root);
+    const prevDelay = process.env.RD_HTTP416_FRESH_RESTART_DELAY_MS;
+    process.env.RD_HTTP416_FRESH_RESTART_DELAY_MS = "0";
+    let downloadCalls = 0;
+
+    globalThis.fetch = async (input: RequestInfo | URL): Promise<Response> => {
+      const url = typeof input === "string" ? input : input instanceof URL ? input.toString() : input.url;
+      if (url.includes("/unrestrict/link")) {
+        return new Response(JSON.stringify({ download: "https://dummy/direct-416-forever", filename: "always-416.mkv", filesize: 1024 }), { status: 200, headers: { "Content-Type": "application/json" } });
+      }
+      throw new Error(`unexpected fetch ${url}`);
+    };
+
+    try {
+      const manager = new DownloadManager(
+        { ...defaultSettings(), token: "rd-token", outputDir: path.join(root, "downloads"), extractDir: path.join(root, "extract"), retryLimit: 0, autoExtract: false, autoReconnect: false },
+        emptySession(),
+        createStoragePaths(path.join(root, "state"))
+      );
+
+      (manager as any).downloadToFile = async () => {
+        downloadCalls += 1;
+        throw new Error("direct_link_retry_exhausted:HTTP 416");
+      };
+
+      manager.addPackages([{ name: "always-416", links: ["https://dummy/always-416"] }]);
+      await manager.start();
+      await waitFor(() => !manager.getSnapshot().session.running, 20000);
+
+      const item = Object.values(manager.getSnapshot().session.items)[0];
+      expect(item?.status).toBe("failed");
+      expect(downloadCalls).toBeGreaterThan(4);
+      expect(downloadCalls).toBeLessThan(30);
+      expect((manager as any).http416FreshRestartByItem.get(item.id)).toBeUndefined();
+    } finally {
+      if (prevDelay === undefined) { delete process.env.RD_HTTP416_FRESH_RESTART_DELAY_MS; } else { process.env.RD_HTTP416_FRESH_RESTART_DELAY_MS = prevDelay; }
+    }
+  }, 25000);
+
   it("retries HTTP 416 in-session when using Debrid-Link API and then completes", async () => {
     const root = fs.mkdtempSync(path.join(os.tmpdir(), "rd-dm-"));
     tempDirs.push(root);