fix(channels): tag-filter row folds overflow into "+N", keeps "…" pinned

The channel manager's tag-filter row wrapped the trailing "…" catalog-actions
menu onto a second line once the chips + Clear outgrew the width. Rework it as
one non-wrapping row: the TAGS editor trigger (left), a single-line chip lane
that collapses overflow into a "+N" pill whose popover holds the rest (still
toggleable), then Clear and the "…" menu pinned right — so "…" always stays on
the first line.

New TagFilterChips reuses the shared measure core (useChipOverflowFit +
fitChipsWithPill), the same compression the feed's applied-filter row uses.

frontend/src/components/Channels.tsx

@@ -18,7 +18,8 @@ import { useChannelTagActions } from "../lib/useChannelTagActions";
 import { useChannelPriority } from "../lib/useChannelPriority";
 import ViewSwitcher, { type ViewOption } from "./ViewSwitcher";
 import ColumnSortControl from "./ColumnSortControl";
-import FilterChipGroup, { filterChipClass } from "./FilterChipGroup";
+import FilterChipGroup from "./FilterChipGroup";
+import TagFilterChips, { type FilterChip } from "./TagFilterChips";
 import ActionMenu, { type ActionMenuItem } from "./ActionMenu";
 import ChannelStatsPopover from "./ChannelStatsPopover";
 import Pager from "./Pager";
@@ -229,6 +230,22 @@ export default function Channels() {
   const noTagOn = tagFilter.includes(NO_TAG_SENTINEL);
   const toggleNoTagFilter = () =>
     setFilters({ ...filters, tags: noTagOn ? [] : [NO_TAG_SENTINEL] });
+  // The tag-filter chips (user tags + the "No tag" sentinel), fed to TagFilterChips which folds any
+  // overflow into a "+N" pill so the row stays one line and the trailing "…" actions can't wrap.
+  const tagFilterChips: FilterChip[] = [
+    ...userTags.map((tg) => ({
+      key: `t${tg.id}`,
+      label: tg.name,
+      active: tagFilter.includes(String(tg.id)),
+      onToggle: () => toggleTagFilter(tg.id),
+    })),
+    {
+      key: NO_TAG_SENTINEL,
+      label: t("channels.tags.noTag"),
+      active: noTagOn,
+      onToggle: toggleNoTagFilter,
+    },
+  ];
   // A focus-channel intent (header "without full history" / tag manager) seeds the search box.
   useEffect(() => {
     if (focusChannelName) setSearch(focusChannelName);
@@ -433,48 +450,31 @@ export default function Channels() {
         {tabs}
         {view === "subscribed" && (
           <div className="px-4 pt-2 pb-2 max-w-384 mx-auto">
-            {/* Your tags (left) share one row with the two catalog-wide actions (right); the channel-name
-          search lives in the shared top SearchBar, tag create/delete in the manager. */}
-            <div className="flex items-center justify-between gap-4 flex-wrap">
-              <div className="flex flex-wrap items-center gap-1.5">
-                {/* The "TAGS" label IS the tags-editor trigger (pencil), replacing the separate
-                    "Manage tags" button; the tooltip explains what tags are + that it's clickable. */}
-                <Tooltip hint={t("channels.tags.yourTagsHint")}>
-                  <button
-                    onClick={() => setTagManagerOpen(true)}
-                    className="mr-1 inline-flex items-center gap-1.5 rounded-lg border border-border px-2 py-1 text-xs uppercase tracking-wide text-muted transition hover:border-accent hover:text-accent"
-                  >
-                    <Pencil className="h-3 w-3" />
-                    {t("channels.tags.label")}
-                  </button>
-                </Tooltip>
-                {userTags.map((tg) => (
-                  <button
-                    key={tg.id}
-                    onClick={() => toggleTagFilter(tg.id)}
-                    aria-pressed={tagFilter.includes(String(tg.id))}
-                    className={filterChipClass}
-                  >
-                    {tg.name}
-                  </button>
-                ))}
+            {/* One non-wrapping row: the TAGS editor trigger (left) + the tag-filter chip lane (folds
+          overflow into "+N") + Clear, then the catalog "…" actions pinned right. It never wraps, so the
+          "…" menu always stays on the first line. Channel-name search lives in the shared top SearchBar. */}
+            <div className="flex items-center gap-2 min-w-0">
+              {/* The "TAGS" label IS the tags-editor trigger (pencil), replacing the separate
+                  "Manage tags" button; the tooltip explains what tags are + that it's clickable. */}
+              <Tooltip hint={t("channels.tags.yourTagsHint")}>
                 <button
-                  onClick={toggleNoTagFilter}
-                  aria-pressed={noTagOn}
-                  className={filterChipClass}
+                  onClick={() => setTagManagerOpen(true)}
+                  className="shrink-0 inline-flex items-center gap-1.5 rounded-lg border border-border px-2 py-1 text-xs uppercase tracking-wide text-muted transition hover:border-accent hover:text-accent"
                 >
-                  {t("channels.tags.noTag")}
+                  <Pencil className="h-3 w-3" />
+                  {t("channels.tags.label")}
                 </button>
-                {tagFilter.length > 0 && (
-                  <button
-                    onClick={() => setFilters({ ...filters, tags: [] })}
-                    className="text-xs px-2 py-1 text-muted hover:text-accent transition"
-                  >
-                    {t("datatable.clear")}
-                  </button>
-                )}
-              </div>
-              {actionButtons}
+              </Tooltip>
+              <TagFilterChips chips={tagFilterChips} className="flex-1" />
+              {tagFilter.length > 0 && (
+                <button
+                  onClick={() => setFilters({ ...filters, tags: [] })}
+                  className="shrink-0 text-xs px-2 py-1 text-muted hover:text-accent transition"
+                >
+                  {t("datatable.clear")}
+                </button>
+              )}
+              <div className="shrink-0">{actionButtons}</div>
             </div>
           </div>
         )}

frontend/src/components/TagFilterChips.tsx

@@ -0,0 +1,128 @@
+import { useEffect, useRef, useState } from "react";
+import { useTranslation } from "react-i18next";
+import { fitChipsWithPill } from "../lib/chipOverflow";
+import { useChipOverflowFit } from "../lib/useChipOverflowFit";
+import { filterChipClass } from "./FilterChipGroup";
+import { useAnchoredPopover, PopoverSurface } from "./AnchoredPopover";
+
+// A single-line row of toggle filter chips that collapses its overflow into a trailing "+N" pill whose
+// popover holds the rest (still toggleable) — the same compression the feed's applied-filter row uses
+// (ActiveFilterChips), sharing the same measure core (useChipOverflowFit + fitChipsWithPill). Used by
+// the channel manager's tag-filter row so it never wraps to a second line and the trailing "…" actions
+// stay pinned on the first line. Any fixed leading (the TAGS editor trigger) / trailing (Clear, the "…"
+// menu) chrome lives OUTSIDE this lane in the caller, so only the chips themselves fold into "+N".
+
+export interface FilterChip {
+  key: string;
+  label: string;
+  active: boolean;
+  onToggle: () => void;
+}
+
+function Chip({ chip, extra }: { chip: FilterChip; extra?: string }) {
+  return (
+    <button
+      type="button"
+      onClick={chip.onToggle}
+      aria-pressed={chip.active}
+      className={`${filterChipClass}${extra ? ` ${extra}` : ""}`}
+    >
+      {chip.label}
+    </button>
+  );
+}
+
+export default function TagFilterChips({
+  chips,
+  className,
+}: {
+  chips: FilterChip[];
+  className?: string;
+}) {
+  const { t } = useTranslation();
+  const rowRef = useRef<HTMLDivElement | null>(null);
+  const chipRefs = useRef<Array<HTMLElement | null>>([]);
+  const pillRef = useRef<HTMLSpanElement | null>(null);
+  // Re-fit when the set, the labels, OR the pressed state change (the pressed paint can change a chip's
+  // width via the `.pill` recipe, so an aria-pressed flip must re-measure too).
+  const key = chips.map((c) => `${c.key}:${c.label}:${c.active ? 1 : 0}`).join("|");
+
+  const visible = useChipOverflowFit<number>({
+    rowRef,
+    chipsRef: chipRefs,
+    pillRef,
+    deps: key,
+    initial: chips.length,
+    decide: (g) =>
+      fitChipsWithPill({ chipRights: g.chipRights, pillW: g.pillW, avail: g.avail, gap: g.gap }),
+  });
+
+  const hidden = chips.length - visible;
+  const [open, setOpen] = useState(false);
+  const pop = useAnchoredPopover({
+    open,
+    onOpenChange: setOpen,
+    mode: "menu",
+    placement: "bottom-end",
+  });
+  // If nothing overflows anymore, the "+N" trigger unmounts — force the popover closed so it can't
+  // linger against a gone reference.
+  useEffect(() => {
+    if (hidden === 0 && open) setOpen(false);
+  }, [hidden, open]);
+
+  const moreLabel = t("channels.tags.moreCount", { count: hidden });
+
+  return (
+    <div className={`relative flex items-center gap-1.5 min-w-0 ${className ?? ""}`}>
+      {/* Hidden measurer: all chips + a sample "+N" pill at natural widths, so the shared fit core can
+          read each chip's right edge, the rem gap and the pill width off real boxes. */}
+      <div
+        aria-hidden
+        className="pointer-events-none invisible absolute left-0 top-0 flex items-center gap-1.5 whitespace-nowrap"
+      >
+        {chips.map((c, i) => (
+          <span
+            key={c.key}
+            ref={(el) => {
+              chipRefs.current[i] = el;
+            }}
+            className="inline-flex"
+          >
+            <span className={filterChipClass}>{c.label}</span>
+          </span>
+        ))}
+        <span ref={pillRef} className={filterChipClass}>
+          +{chips.length}
+        </span>
+      </div>
+
+      <div ref={rowRef} className="flex items-center gap-1.5 min-w-0 flex-1 overflow-hidden">
+        {chips.slice(0, visible).map((c) => (
+          <Chip key={c.key} chip={c} extra="shrink-0" />
+        ))}
+        {hidden > 0 && (
+          <button
+            ref={pop.refs.setReference}
+            type="button"
+            aria-label={moreLabel}
+            className={`${filterChipClass} shrink-0 ${open ? "border-accent text-accent" : ""}`}
+            {...pop.getReferenceProps()}
+          >
+            +{hidden}
+          </button>
+        )}
+      </div>
+
+      <PopoverSurface
+        popover={pop}
+        ariaLabel={moreLabel}
+        className="glass-menu flex max-w-[22rem] flex-wrap items-center gap-1.5 rounded-xl p-2 shadow-lg animate-[popIn_0.16s_ease]"
+      >
+        {chips.slice(visible).map((c) => (
+          <Chip key={c.key} chip={c} />
+        ))}
+      </PopoverSurface>
+    </div>
+  );
+}