Fix cookie fallback breaking yt-dlp in Docker; add OAuth2 auth flow

- _cookie_args() no longer falls through to --cookies-from-browser when
  cookies_file is configured but missing. Firefox isn't installed in the
  Docker image, so that fallback caused yt-dlp to exit with empty stdout
  and every metadata fetch to return "Video not found on YouTube".
- fetch_video_metadata() now retries without auth args if the first call
  fails, so a broken cookie config can't block public video fetches.
- Add use_oauth2 setting + full device-auth flow (POST /settings/oauth2-init,
  GET /settings/oauth2-status) with OAuth2Section UI in Settings page.
- Add GET /settings/ytdlp-test diagnostics endpoint.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

backend/main.py

@@ -70,6 +70,7 @@ def on_startup():
         "ALTER TABLE user_settings ADD COLUMN feed_weight_recency REAL DEFAULT 5.0",
         "ALTER TABLE user_settings ADD COLUMN feed_weight_affinity REAL DEFAULT 5.0",
         "ALTER TABLE user_settings ADD COLUMN feed_weight_channel REAL DEFAULT 5.0",
+        "ALTER TABLE user_settings ADD COLUMN use_oauth2 INTEGER DEFAULT 0",
         """CREATE TABLE IF NOT EXISTS search_history (
             id INTEGER PRIMARY KEY AUTOINCREMENT,
             user_id INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
@@ -144,6 +145,7 @@ def on_startup():
             ytdlp_service.set_max_concurrent(first_user_settings.max_concurrent_downloads)
             ytdlp_service.set_cookies_browser(first_user_settings.cookies_browser or "")
             ytdlp_service.set_cookies_file(first_user_settings.cookies_file or "")
+            ytdlp_service.set_oauth2(bool(getattr(first_user_settings, "use_oauth2", False)))
     finally:
         db.close()
 

backend/models.py

@@ -118,6 +118,7 @@ class UserSettings(Base):
     feed_weight_recency = Column(Float, default=5.0)   # 0–10
     feed_weight_affinity = Column(Float, default=5.0)  # 0–10
     feed_weight_channel = Column(Float, default=5.0)   # 0–10
+    use_oauth2 = Column(Boolean, default=False)
 
 
 class DiscoveryQueue(Base):

backend/routers/settings.py

@@ -33,6 +33,7 @@ class SettingsOut(BaseModel):
     feed_weight_recency: float = 5.0
     feed_weight_affinity: float = 5.0
     feed_weight_channel: float = 5.0
+    use_oauth2: bool = False
 
     model_config = {"from_attributes": True}
 
@@ -53,6 +54,7 @@ class SettingsPatch(BaseModel):
     feed_weight_recency: Optional[float] = Field(None, ge=0.0, le=10.0)
     feed_weight_affinity: Optional[float] = Field(None, ge=0.0, le=10.0)
     feed_weight_channel: Optional[float] = Field(None, ge=0.0, le=10.0)
+    use_oauth2: Optional[bool] = None
 
 
 def _get_or_create(db: Session, user_id: int) -> UserSettings:
@@ -118,6 +120,9 @@ def update_settings(
         s.feed_weight_affinity = body.feed_weight_affinity
     if body.feed_weight_channel is not None:
         s.feed_weight_channel = body.feed_weight_channel
+    if body.use_oauth2 is not None:
+        s.use_oauth2 = body.use_oauth2
+        ytdlp.set_oauth2(body.use_oauth2)
 
     db.commit()
     db.refresh(s)
@@ -165,3 +170,75 @@ def delete_cookies_file(
     db.commit()
     db.refresh(s)
     return s
+
+
+@router.post("/oauth2-init")
+def oauth2_init(
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """Start a yt-dlp OAuth2 device-auth flow. Returns the device URL and code immediately."""
+    state = ytdlp.start_oauth2_flow()
+    return state
+
+
+@router.get("/oauth2-status")
+def oauth2_status(
+    current_user: User = Depends(get_current_user),
+):
+    """Poll the current OAuth2 flow status."""
+    return ytdlp.get_oauth2_status()
+
+
+@router.post("/oauth2-enable", response_model=SettingsOut)
+def oauth2_enable(
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """Mark OAuth2 as the active auth method after a successful flow."""
+    s = _get_or_create(db, current_user.id)
+    s.use_oauth2 = True
+    ytdlp.set_oauth2(True)
+    db.commit()
+    db.refresh(s)
+    return s
+
+
+@router.post("/oauth2-disable", response_model=SettingsOut)
+def oauth2_disable(
+    db: Session = Depends(get_db),
+    current_user: User = Depends(get_current_user),
+):
+    """Disable OAuth2 auth, falling back to cookies."""
+    s = _get_or_create(db, current_user.id)
+    s.use_oauth2 = False
+    ytdlp.set_oauth2(False)
+    db.commit()
+    db.refresh(s)
+    return s
+
+
+@router.get("/ytdlp-test")
+def ytdlp_test(
+    current_user: User = Depends(get_current_user),
+):
+    """Run a quick yt-dlp metadata fetch on a public video and return raw output for diagnostics."""
+    import subprocess
+    cookie_args = ytdlp._cookie_args()
+    result = subprocess.run(
+        [
+            "yt-dlp",
+            "https://www.youtube.com/watch?v=dQw4w9WgXcQ",
+            "--dump-json", "--no-download", "--no-playlist",
+            "--extractor-args", "youtube:player_client=tv,ios,web",
+            *cookie_args,
+        ],
+        capture_output=True, text=True, timeout=30,
+    )
+    return {
+        "returncode": result.returncode,
+        "cookie_args": cookie_args,
+        "stdout_lines": result.stdout.splitlines()[:5],
+        "stderr_tail": result.stderr.splitlines()[-20:],
+        "success": result.returncode == 0,
+    }

backend/services/ytdlp.py

@@ -213,17 +213,20 @@ def fetch_video_metadata(video_id: str) -> dict | None:
     url = f"https://www.youtube.com/watch?v={video_id}"
     cookie_args = _cookie_args()
     print(f"[fetch_meta] video={video_id} cookie_args={cookie_args!r}", flush=True)
-    stdout, stderr, code = _run([
+    base_cmd = [
-        "yt-dlp",
+        "yt-dlp", url,
-        url,
+        "--dump-json", "--no-download", "--no-playlist",
-        "--dump-json",
-        "--no-download",
-        "--no-playlist",
         "--extractor-args", "youtube:player_client=tv,ios,web",
-        *cookie_args,
+    ]
-    ], timeout=30)
+    stdout, stderr, code = _run([*base_cmd, *cookie_args], timeout=30)
     if code != 0:
         print(f"[fetch_meta] FAILED code={code} stderr={stderr[:500]!r}", flush=True)
+        # Retry without auth args — broken cookie config shouldn't block public videos
+        if cookie_args:
+            print(f"[fetch_meta] retrying without cookie args", flush=True)
+            stdout, stderr, code = _run(base_cmd, timeout=30)
+            if code != 0:
+                print(f"[fetch_meta] retry also FAILED code={code}", flush=True)
 
     for line in stdout.splitlines():
         line = line.strip()
@@ -406,10 +409,15 @@ _SEMAPHORE = threading.Semaphore(3)
 _semaphore_lock = threading.Lock()
 _cookies_browser: str = ""
 _cookies_file: str = ""
+_use_oauth2: bool = False
 _cookies_lock = threading.Lock()
 
 _AUTO_COOKIES_PATHS = ["/data/cookies.txt"]
 
+# OAuth2 device-auth flow state (shared across threads)
+_oauth2_state: dict = {"status": "idle", "device_url": None, "code": None, "error": None}
+_oauth2_state_lock = threading.Lock()
+
 
 def set_max_concurrent(n: int) -> None:
     global _SEMAPHORE
@@ -429,23 +437,103 @@ def set_cookies_file(path: str) -> None:
         _cookies_file = path.strip()
 
 
+def set_oauth2(enabled: bool) -> None:
+    global _use_oauth2
+    with _cookies_lock:
+        _use_oauth2 = bool(enabled)
+
+
 def _cookie_args() -> list[str]:
     with _cookies_lock:
         cf = _cookies_file
         b = _cookies_browser
-    # Prefer explicit cookies file
+        oauth2 = _use_oauth2
+    # OAuth2 token auth — IP-independent, works on datacenter servers
+    if oauth2:
+        return ["--username", "oauth2", "--password", ""]
+    # Explicit cookies file
     if cf and Path(cf).exists():
         return ["--cookies", cf]
     # Auto-detect cookies.txt in well-known Docker locations
     for candidate in _AUTO_COOKIES_PATHS:
         if Path(candidate).exists():
             return ["--cookies", candidate]
-    # Fall back to browser (works in local dev, not in Docker)
+    # Browser cookies — only when no file path was ever configured.
-    if b:
+    # If cookies_file is set but missing, the user intended file auth; falling
+    # through to a browser that isn't installed in Docker would silently break
+    # all yt-dlp calls with an empty-stdout failure.
+    if b and not cf:
         return ["--cookies-from-browser", b]
     return []
 
 
+def get_oauth2_status() -> dict:
+    with _oauth2_state_lock:
+        return dict(_oauth2_state)
+
+
+def start_oauth2_flow() -> dict:
+    """Start yt-dlp OAuth2 device-auth flow in a background thread.
+
+    yt-dlp prints a Google device URL + code to stderr, then polls until the user
+    completes sign-in on their phone/browser. Token is cached to /data/yt-dlp-cache
+    (set globally via /etc/yt-dlp.conf) and reused on every subsequent call that
+    passes --username oauth2 --password "".
+    """
+    import time as _time
+
+    with _oauth2_state_lock:
+        if _oauth2_state["status"] == "pending":
+            return dict(_oauth2_state)
+        _oauth2_state.update({"status": "pending", "device_url": None, "code": None, "error": None})
+
+    def _run_flow():
+        try:
+            process = subprocess.Popen(
+                [
+                    "yt-dlp",
+                    "--username", "oauth2", "--password", "",
+                    "https://www.youtube.com/",
+                ],
+                stdout=subprocess.DEVNULL,
+                stderr=subprocess.PIPE,
+                text=True,
+            )
+            for line in process.stderr:
+                line = line.strip()
+                print(f"[oauth2] {line}", flush=True)
+                if "google.com/device" in line or "youtube.com/device" in line:
+                    url_m = re.search(r"(https://[^\s]+)", line)
+                    code_m = re.search(r"code[:\s]+([A-Z0-9]{4}-[A-Z0-9]{4}|[A-Z0-9-]{6,})", line, re.IGNORECASE)
+                    with _oauth2_state_lock:
+                        _oauth2_state["device_url"] = (url_m.group(1) if url_m else "https://www.google.com/device")
+                        _oauth2_state["code"] = code_m.group(1) if code_m else None
+            process.wait()
+            with _oauth2_state_lock:
+                if process.returncode == 0:
+                    _oauth2_state["status"] = "complete"
+                else:
+                    _oauth2_state["status"] = "error"
+                    _oauth2_state["error"] = f"yt-dlp exited with code {process.returncode}"
+        except Exception as exc:
+            with _oauth2_state_lock:
+                _oauth2_state["status"] = "error"
+                _oauth2_state["error"] = str(exc)
+
+    threading.Thread(target=_run_flow, daemon=True).start()
+
+    # Wait up to 10 s for the device URL to appear in stderr
+    import time as _time
+    for _ in range(100):
+        with _oauth2_state_lock:
+            if _oauth2_state["device_url"] or _oauth2_state["status"] in ("complete", "error"):
+                break
+        _time.sleep(0.1)
+
+    with _oauth2_state_lock:
+        return dict(_oauth2_state)
+
+
 def start_download(
     video_id: str,
     download_id: int,

frontend/src/api/index.js

@@ -107,6 +107,11 @@ export const uploadCookiesFile = (file) => {
   return api.post("/settings/cookies-file", form);
 };
 export const deleteCookiesFile = () => api.delete("/settings/cookies-file");
+export const initOAuth2 = () => api.post("/settings/oauth2-init");
+export const getOAuth2Status = () => api.get("/settings/oauth2-status");
+export const enableOAuth2 = () => api.post("/settings/oauth2-enable");
+export const disableOAuth2 = () => api.post("/settings/oauth2-disable");
+export const testYtdlp = () => api.get("/settings/ytdlp-test");
 
 // Discovery
 export const getDiscovery = (offset = 0, limit = 50) =>

frontend/src/pages/Settings.jsx

@@ -1,6 +1,6 @@
-import { useState, useRef } from "react";
+import { useState, useRef, useEffect } from "react";
 import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
-import { getSettings, updateSettings, exportData, uploadCookiesFile, deleteCookiesFile, getAdminUsers, deleteAdminUser, getAdminConfig, updateAdminConfig } from "../api";
+import { getSettings, updateSettings, exportData, uploadCookiesFile, deleteCookiesFile, getAdminUsers, deleteAdminUser, getAdminConfig, updateAdminConfig, initOAuth2, getOAuth2Status, enableOAuth2, disableOAuth2, testYtdlp } from "../api";
 import { useAuth } from "../hooks/useAuth";
 
 const REGION_OPTIONS = [
@@ -295,6 +295,155 @@ function CookiesSection({ s, qc, set }) {
   );
 }
 
+function OAuth2Section({ s, qc }) {
+  const [flowState, setFlowState] = useState(null); // null | {status, device_url, code}
+  const [polling, setPolling] = useState(false);
+
+  const isEnabled = s?.use_oauth2 ?? false;
+
+  const initMut = useMutation({
+    mutationFn: initOAuth2,
+    onSuccess: (res) => {
+      setFlowState(res.data);
+      if (res.data.status === "pending") setPolling(true);
+    },
+  });
+
+  const enableMut = useMutation({
+    mutationFn: enableOAuth2,
+    onSuccess: (res) => qc.setQueryData(["settings"], res.data),
+  });
+
+  const disableMut = useMutation({
+    mutationFn: disableOAuth2,
+    onSuccess: (res) => { qc.setQueryData(["settings"], res.data); setFlowState(null); },
+  });
+
+  // Poll for completion when a flow is running
+  useEffect(() => {
+    if (!polling) return;
+    const id = setInterval(async () => {
+      try {
+        const res = await getOAuth2Status();
+        const st = res.data;
+        setFlowState(st);
+        if (st.status === "complete") {
+          setPolling(false);
+          enableMut.mutate();
+        } else if (st.status === "error") {
+          setPolling(false);
+        }
+      } catch {}
+    }, 2000);
+    return () => clearInterval(id);
+  }, [polling]);
+
+  return (
+    <Section title="Google OAuth2 (advanced)">
+      <div className="px-5 py-4 flex flex-col gap-3">
+        <p className="text-xs text-zinc-500">
+          OAuth2 lets yt-dlp authenticate directly with your Google account — useful if cookies keep expiring.
+          You'll need to visit a URL on any device to approve access. The token is cached on the server.
+        </p>
+
+        {isEnabled && !flowState && (
+          <div className="flex items-center justify-between bg-zinc-800 rounded-xl px-4 py-3">
+            <div className="flex items-center gap-2">
+              <svg className="w-4 h-4 text-green-400 shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M5 13l4 4L19 7" />
+              </svg>
+              <span className="text-xs text-zinc-300">OAuth2 active</span>
+            </div>
+            <div className="flex items-center gap-3">
+              <button
+                onClick={() => initMut.mutate()}
+                disabled={initMut.isPending}
+                className="text-xs text-zinc-400 hover:text-zinc-200 transition-colors"
+              >
+                reauthorize
+              </button>
+              <button
+                onClick={() => disableMut.mutate()}
+                className="text-xs text-red-400 hover:text-red-300 transition-colors"
+              >
+                disable
+              </button>
+            </div>
+          </div>
+        )}
+
+        {!isEnabled && !flowState && (
+          <button
+            onClick={() => initMut.mutate()}
+            disabled={initMut.isPending}
+            className="flex items-center justify-center gap-2 px-4 py-2.5 rounded-xl bg-zinc-800 hover:bg-zinc-700 text-sm text-zinc-300 transition-colors disabled:opacity-50"
+          >
+            {initMut.isPending ? (
+              <div className="w-4 h-4 border-2 border-accent border-t-transparent rounded-full animate-spin" />
+            ) : (
+              <svg className="w-4 h-4" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M13 10V3L4 14h7v7l9-11h-7z" />
+              </svg>
+            )}
+            {initMut.isPending ? "Starting…" : "Connect with Google OAuth2"}
+          </button>
+        )}
+
+        {flowState && flowState.status === "pending" && (
+          <div className="flex flex-col gap-3 bg-zinc-800 rounded-xl px-4 py-4">
+            <div className="flex items-center gap-2">
+              <div className="w-3 h-3 border-2 border-accent border-t-transparent rounded-full animate-spin shrink-0" />
+              <p className="text-xs text-zinc-300 font-medium">Waiting for authorization…</p>
+            </div>
+            {flowState.device_url && (
+              <div className="flex flex-col gap-1">
+                <p className="text-xs text-zinc-500">
+                  Open this URL on any device and sign into your Google account:
+                </p>
+                <a
+                  href={flowState.device_url}
+                  target="_blank"
+                  rel="noopener noreferrer"
+                  className="text-xs text-accent font-mono break-all hover:underline"
+                >
+                  {flowState.device_url}
+                </a>
+                {flowState.code && (
+                  <p className="text-xs text-zinc-400 mt-1">
+                    Code: <span className="font-mono text-zinc-200 font-semibold">{flowState.code}</span>
+                  </p>
+                )}
+              </div>
+            )}
+          </div>
+        )}
+
+        {flowState && flowState.status === "complete" && (
+          <div className="flex items-center gap-2 bg-green-950/40 rounded-xl px-4 py-3">
+            <svg className="w-4 h-4 text-green-400 shrink-0" fill="none" stroke="currentColor" viewBox="0 0 24 24">
+              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M5 13l4 4L19 7" />
+            </svg>
+            <p className="text-xs text-green-400">Authorized! OAuth2 is now active.</p>
+          </div>
+        )}
+
+        {flowState && flowState.status === "error" && (
+          <div className="flex flex-col gap-1 bg-red-950/40 rounded-xl px-4 py-3">
+            <p className="text-xs text-red-400">OAuth2 flow failed.</p>
+            {flowState.error && <p className="text-[11px] text-red-500 font-mono">{flowState.error}</p>}
+            <button
+              onClick={() => { setFlowState(null); initMut.mutate(); }}
+              className="text-xs text-zinc-400 hover:text-zinc-200 mt-1 text-left"
+            >
+              Try again
+            </button>
+          </div>
+        )}
+      </div>
+    </Section>
+  );
+}
+
 export default function SettingsPage() {
   const { user } = useAuth();
   const qc = useQueryClient();
@@ -341,6 +490,7 @@ export default function SettingsPage() {
 
       {/* YouTube authentication */}
       <CookiesSection s={s} qc={qc} set={set} />
+      <OAuth2Section s={s} qc={qc} />
 
       {/* Download quality */}
       <Section title="Download quality">