3syisgbyq: Add a reusable bottom sheet with the comments and composer sheets on the phone feed

src/components/BottomSheet.tsx

@@ -0,0 +1,90 @@
+"use client";
+
+// Bottom sheet (spec "Sheets"): slides up over a dimmed, blurred backdrop with a
+// grab handle, a serif title and a close button. Reused by the comments,
+// composer and Discover sheets. Styles live in src/styles/sheet.css.
+import { useEffect, useId, useRef, type ReactNode } from "react";
+
+const FOCUSABLE = 'button:not(:disabled), a[href], input:not(:disabled), textarea:not(:disabled), select:not(:disabled), [tabindex]:not([tabindex="-1"])';
+
+export interface BottomSheetProps {
+  title: string;
+  onClose: () => void;
+  children: ReactNode;
+  /** Extra class on the sheet, for per-sheet sizing. */
+  className?: string;
+}
+
+export function BottomSheet({ title, onClose, children, className }: BottomSheetProps) {
+  const sheet = useRef<HTMLElement | null>(null);
+  const titleId = useId();
+  const closeRef = useRef(onClose);
+  closeRef.current = onClose;
+
+  useEffect(() => {
+    const el = sheet.current;
+    if (!el) return;
+    const opener = document.activeElement as HTMLElement | null;
+    // Focus moves into the sheet: its first field, else the sheet itself.
+    const first = el.querySelector<HTMLElement>("input, textarea") ?? el.querySelector<HTMLElement>(FOCUSABLE);
+    (first ?? el).focus({ preventScroll: true });
+
+    const prevOverflow = document.body.style.overflow;
+    document.body.style.overflow = "hidden";
+
+    function onKey(e: KeyboardEvent) {
+      if (e.key === "Escape") {
+        // An open emoji popover closes first; it handles Escape itself.
+        if (el?.querySelector('[aria-haspopup="dialog"][aria-expanded="true"]')) return;
+        e.preventDefault();
+        closeRef.current();
+        return;
+      }
+      if (e.key !== "Tab" || !el) return;
+      const items = [...el.querySelectorAll<HTMLElement>(FOCUSABLE)].filter((n) => n.offsetParent !== null || n === document.activeElement);
+      if (!items.length) return;
+      const a = items[0];
+      const z = items[items.length - 1];
+      if (e.shiftKey && (document.activeElement === a || document.activeElement === el)) {
+        e.preventDefault();
+        z.focus();
+      } else if (!e.shiftKey && document.activeElement === z) {
+        e.preventDefault();
+        a.focus();
+      }
+    }
+    document.addEventListener("keydown", onKey);
+    return () => {
+      document.removeEventListener("keydown", onKey);
+      document.body.style.overflow = prevOverflow;
+      // Focus returns to the opener (when it is still on the page).
+      if (opener && opener.isConnected) opener.focus({ preventScroll: true });
+    };
+  }, []);
+
+  return (
+    <>
+      <button type="button" className="sheet-bg" aria-label="Close" tabIndex={-1} onClick={onClose} data-testid="sheet-backdrop" />
+      <section
+        ref={sheet}
+        className={`sheet${className ? ` ${className}` : ""}`}
+        role="dialog"
+        aria-modal="true"
+        aria-labelledby={titleId}
+        tabIndex={-1}
+        data-testid="bottom-sheet"
+      >
+        <span className="sheet-grab" aria-hidden="true" />
+        <div className="sheet-h">
+          <h2 id={titleId} className="type-title type-title-strong">{title}</h2>
+          <button type="button" className="sheet-x" aria-label="Close" onClick={onClose}>
+            <svg viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="1.7" strokeLinecap="round" strokeLinejoin="round" aria-hidden="true">
+              <path d="M6 6l12 12M18 6 6 18" />
+            </svg>
+          </button>
+        </div>
+        <div className="sheet-body">{children}</div>
+      </section>
+    </>
+  );
+}

src/components/MobileFeed.tsx

@@ -1,6 +1,6 @@
 "use client";
 
-import { useEffect, useRef, useState, type MouseEvent, type Ref } from "react";
+import { useCallback, useEffect, useRef, useState, type MouseEvent, type Ref } from "react";
 import { canDelete, formatDuration, isPlayableVideo, relativeTime, type CardMedia, type CardPost } from "@/lib/feed-model";
 import { GrowButton } from "./Buttons";
 import { HexAvatar } from "./HexAvatar";
@@ -8,6 +8,9 @@ import { PlayIcon, PostMenu } from "./PostCard";
 import { VideoPlayer } from "./VideoPlayer";
 import { FeaturedCarousel } from "./FeaturedCarousel";
 import { MobileDock } from "./MobileDock";
+import { BottomSheet } from "./BottomSheet";
+import { CommentsSection } from "./CommentsSection";
+import { Composer } from "./Composer";
 import type { DiscoverExpert } from "@/lib/discover";
 import type { FeedViewProps } from "./FeedView";
 
@@ -278,6 +281,17 @@ function LoadSlide({ index, current, sentinelRef }: { index: number; current: bo
 export function MobileFeed(p: FeedViewProps) {
   const reel = useRef<HTMLDivElement | null>(null);
   const [current, setCurrent] = useState(0);
+  // The open sheet: the comments of one post, the composer, or none.
+  const [sheet, setSheet] = useState<{ kind: "comments"; postId: string } | { kind: "composer" } | null>(null);
+  const closeSheet = useCallback(() => setSheet(null), []);
+  // A successful post closes the composer: publishing ends with no error and an emptied draft.
+  const wasBusy = useRef(false);
+  const composerBusy = !!p.composer?.busy;
+  const composerClear = !!p.composer && !p.composer.error && !p.composer.value && !p.composer.file;
+  useEffect(() => {
+    if (wasBusy.current && !composerBusy && composerClear) setSheet((s) => (s?.kind === "composer" ? null : s));
+    wasBusy.current = composerBusy;
+  }, [composerBusy, composerClear]);
   const onCurrentChange = p.onCurrentChange;
   const showLoad = p.status === "loading" || (p.status === "ready" && !p.loadMoreFailed && (p.loadingMore || !!p.hasMore));
   const experts = p.featuredExperts ?? [];
@@ -421,11 +435,27 @@ export function MobileFeed(p: FeedViewProps) {
           slide={{ index, kind, post: currentPost }}
           onToggleLike={p.onToggleLike}
           likeBusy={currentPost ? p.likeBusy?.has(currentPost.key) : false}
-          onOpenComments={p.onOpenComments}
-          onOpenComposer={p.onOpenComposer}
+          onOpenComments={(postId) => {
+            setSheet({ kind: "comments", postId });
+            p.onOpenComments?.(postId);
+          }}
+          onOpenComposer={() => {
+            setSheet({ kind: "composer" });
+            p.onOpenComposer?.();
+          }}
           onOpenMore={p.onOpenMore}
         />
       ) : null}
+      {sheet?.kind === "comments" ? (
+        <BottomSheet title="Comments" onClose={closeSheet} className="sheet-comments">
+          <CommentsSection postId={sheet.postId} onSignedOut={p.onSignedOut} />
+        </BottomSheet>
+      ) : null}
+      {sheet?.kind === "composer" && p.composer ? (
+        <BottomSheet title="New post" onClose={closeSheet} className="sheet-composer">
+          <Composer {...p.composer} />
+        </BottomSheet>
+      ) : null}
     </section>
   );
 }