refactor(ui): useDismiss hook for outside-click/Escape close

lib/useDismiss.ts replaces the identical mousedown-outside + Escape effect that
DataTable (filter popover), Channels (tag picker) and AddToPlaylist each hand-rolled.
Positioning stays with each caller (it genuinely varies); AddToPlaylist keeps its
own resize/scroll reposition effect.

frontend/src/components/AddToPlaylist.tsx

@@ -4,6 +4,7 @@ import { useTranslation } from "react-i18next";
 import { useQuery, useQueryClient } from "@tanstack/react-query";
 import { Check, ListPlus, Plus, Youtube } from "lucide-react";
 import { api, type Playlist } from "../lib/api";
+import { useDismiss } from "../lib/useDismiss";
 
 // A small popover (portaled to body, so the feed grid can't clip it) for toggling a
 // video's membership in the user's playlists, with inline "new playlist" creation.
@@ -59,25 +60,13 @@ export default function AddToPlaylist({
     setOpen((o) => !o);
   }
 
+  useDismiss(open, () => setOpen(false), [panelRef, triggerRef]);
+  // Keep the panel anchored to the trigger as the page resizes/scrolls while open.
   useEffect(() => {
     if (!open) return;
-    function onDoc(e: MouseEvent) {
-      if (
-        !panelRef.current?.contains(e.target as Node) &&
-        !triggerRef.current?.contains(e.target as Node)
-      )
-        setOpen(false);
-    }
-    function onKey(e: KeyboardEvent) {
-      if (e.key === "Escape") setOpen(false);
-    }
-    document.addEventListener("mousedown", onDoc);
-    document.addEventListener("keydown", onKey);
     window.addEventListener("resize", place);
     window.addEventListener("scroll", place, true);
     return () => {
-      document.removeEventListener("mousedown", onDoc);
-      document.removeEventListener("keydown", onKey);
       window.removeEventListener("resize", place);
       window.removeEventListener("scroll", place, true);
     };

frontend/src/components/Channels.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useRef, useState } from "react";
+import { useRef, useState } from "react";
 import { Trans, useTranslation } from "react-i18next";
 import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
 import {
@@ -14,6 +14,7 @@ import {
   UserMinus,
 } from "lucide-react";
 import { api, HttpError, type ManagedChannel, type Tag } from "../lib/api";
+import { useDismiss } from "../lib/useDismiss";
 import { formatEta, formatViews, relativeTime } from "../lib/format";
 import { notify } from "../lib/notifications";
 import Tooltip from "./Tooltip";
@@ -616,19 +617,7 @@ function TagsCell({
   const { t } = useTranslation();
   const [open, setOpen] = useState(false);
   const ref = useRef<HTMLDivElement | null>(null);
-  useEffect(() => {
-    if (!open) return;
-    const onDown = (e: MouseEvent) => {
-      if (!ref.current?.contains(e.target as Node)) setOpen(false);
-    };
-    const onKey = (e: KeyboardEvent) => e.key === "Escape" && setOpen(false);
-    document.addEventListener("mousedown", onDown);
-    document.addEventListener("keydown", onKey);
-    return () => {
-      document.removeEventListener("mousedown", onDown);
-      document.removeEventListener("keydown", onKey);
-    };
-  }, [open]);
+  useDismiss(open, () => setOpen(false), ref);
   if (userTags.length === 0) return null;
   // Show only the tags actually attached to this channel; the “+” opens a per-channel
   // picker to attach/detach (kept the convenient "kirakás" without listing every tag

frontend/src/components/DataTable.tsx

@@ -1,6 +1,7 @@
 import { useEffect, useRef, useState, type ReactNode } from "react";
 import { useTranslation } from "react-i18next";
 import { ArrowDown, ArrowUp, ChevronLeft, ChevronRight, ListFilter, X } from "lucide-react";
+import { useDismiss } from "../lib/useDismiss";
 
 // A reusable, client-side data table: per-column sort + filter (in the header) + pagination,
 // with its sort/filter/page state optionally persisted to localStorage so a reload (F5) keeps
@@ -121,21 +122,7 @@ export default function DataTable<T>({
     setPage(0);
   }, [resetFiltersToken]);
 
-  useEffect(() => {
-    if (!openFilter) return;
-    function onDown(e: MouseEvent) {
-      if (!popRef.current?.contains(e.target as Node)) setOpenFilter(null);
-    }
-    function onKey(e: KeyboardEvent) {
-      if (e.key === "Escape") setOpenFilter(null);
-    }
-    document.addEventListener("mousedown", onDown);
-    document.addEventListener("keydown", onKey);
-    return () => {
-      document.removeEventListener("mousedown", onDown);
-      document.removeEventListener("keydown", onKey);
-    };
-  }, [openFilter]);
+  useDismiss(!!openFilter, () => setOpenFilter(null), popRef);
 
   const filtered = rows.filter((row) =>
     columns.every((col) => {

frontend/src/lib/useDismiss.ts

@@ -0,0 +1,32 @@
+import { useEffect, type RefObject } from "react";
+
+/** While `active`, close (call `onClose`) on Escape or a mousedown outside ALL of the given
+ * element(s). The reusable half of the popover/dropdown pattern that several components each
+ * hand-rolled; positioning stays with the caller (it varies per popover). Pass the panel ref
+ * (and optionally a trigger ref so clicking the trigger doesn't immediately re-close). */
+export function useDismiss(
+  active: boolean,
+  onClose: () => void,
+  refs: RefObject<HTMLElement | null> | RefObject<HTMLElement | null>[],
+): void {
+  useEffect(() => {
+    if (!active) return;
+    const list = Array.isArray(refs) ? refs : [refs];
+    const onDown = (e: MouseEvent) => {
+      const target = e.target as Node;
+      if (!list.some((r) => r.current?.contains(target))) onClose();
+    };
+    const onKey = (e: KeyboardEvent) => {
+      if (e.key === "Escape") onClose();
+    };
+    document.addEventListener("mousedown", onDown);
+    document.addEventListener("keydown", onKey);
+    return () => {
+      document.removeEventListener("mousedown", onDown);
+      document.removeEventListener("keydown", onKey);
+    };
+    // Matches the original effects: (re)subscribe only when open/closed toggles. Refs are
+    // stable and onClose is read fresh from this run's closure.
+    // eslint-disable-next-line react-hooks/exhaustive-deps
+  }, [active]);
+}