fix(inbox): reliable unread reset + sidebar green-dot indicator

Two issues:

1. Unread count didn't always clear when opening / viewing a
   conversation. The reset effect keyed off conversationId only, so
   a new inbound message arriving while the thread was already open
   would get the server to bump unread_count to 1, but the reset
   effect wouldn't re-fire. Split the fetch and unread-reset effects:
   fetch stays keyed on conversationId (no unnecessary refetches on
   every new message), and a second effect keyed on [conversationId,
   hasUnread] flips unread back to 0 whenever it surfaces on the
   active conversation. The hasUnread gate still prevents the
   reset→update→realtime→re-run loop.

2. No indicator elsewhere in the app when new messages arrive. Added
   useTotalUnread() hook — one-time query + realtime subscription on
   the conversations table — and a pulsing green dot on the sidebar
   Inbox entry when totalUnread > 0. Dot is hidden while on /inbox
   itself (redundant with the per-conversation badges there).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/components/inbox/message-thread.tsx

@@ -114,6 +114,10 @@ export function MessageThread({
   const conversationId = conversation?.id;
   const hasUnread = (conversation?.unread_count ?? 0) > 0;
 
+  // Fetch messages whenever the selected conversation changes. Kept
+  // separate from the unread-reset effect so that incoming messages
+  // arriving while the thread is open don't trigger a full refetch —
+  // they only flip hasUnread, which only the reset effect listens to.
   useEffect(() => {
     if (!conversationId) return;
 
@@ -137,29 +141,35 @@ export function MessageThread({
         onMessagesLoadedRef.current(data ?? []);
       }
 
-      // Only issue the unread_count reset when there's actually something
-      // to reset. Unconditional updates fire a realtime UPDATE event every
-      // time, which — combined with the parent's conversation-event handler
-      // — used to retrigger this effect in a loop.
-      if (hasUnread) {
-        await supabase
-          .from("conversations")
-          .update({ unread_count: 0 })
-          .eq("id", conversationId);
-      }
-
       if (!cancelled) setLoading(false);
     })();
 
     return () => {
       cancelled = true;
     };
-    // Re-fetch only when the selected conversation changes. `hasUnread`
-    // is used inside but is a boolean derived from conversation; the
-    // conversationId dep is the real trigger.
-    // eslint-disable-next-line react-hooks/exhaustive-deps
   }, [conversationId]);
 
+  // Reset the server-side unread_count to 0 whenever an unread count
+  // surfaces on the active conversation — covers both (a) opening a
+  // conversation that had unread messages and (b) new messages arriving
+  // while the user is already viewing the thread (webhook server-bumps
+  // unread_count to N+1; the realtime UPDATE propagates it into the
+  // client, which re-runs this effect and flips it back to 0).
+  //
+  // Guarding on hasUnread prevents the eq-update loop: once unread_count
+  // is 0 the condition is false, so no further UPDATE is issued.
+  useEffect(() => {
+    if (!conversationId || !hasUnread) return;
+    const supabase = createClient();
+    supabase
+      .from("conversations")
+      .update({ unread_count: 0 })
+      .eq("id", conversationId)
+      .then(({ error }) => {
+        if (error) console.error("Failed to reset unread_count:", error);
+      });
+  }, [conversationId, hasUnread]);
+
   // Auto-scroll to bottom on new messages
   useEffect(() => {
     if (scrollRef.current) {

src/components/layout/sidebar.tsx

@@ -4,6 +4,7 @@ import Link from "next/link";
 import { usePathname } from "next/navigation";
 import { cn } from "@/lib/utils";
 import { useAuth } from "@/hooks/use-auth";
+import { useTotalUnread } from "@/hooks/use-total-unread";
 import {
   LayoutDashboard,
   MessageSquare,
@@ -31,6 +32,7 @@ const bottomNavItems = [
 export function Sidebar() {
   const pathname = usePathname();
   const { profile, signOut } = useAuth();
+  const totalUnread = useTotalUnread();
 
   return (
     <aside className="flex h-screen w-60 flex-col border-r border-slate-800 bg-slate-900">
@@ -50,6 +52,13 @@ export function Sidebar() {
               pathname === item.href ||
               (item.href !== "/dashboard" && pathname.startsWith(item.href));
 
+            // Green dot on the Inbox entry when there are unread
+            // conversations AND the user isn't currently in /inbox (they'd
+            // be seeing the unread badges on the conversation list there,
+            // so the sidebar dot would be redundant).
+            const showUnreadDot =
+              item.href === "/inbox" && totalUnread > 0 && !isActive;
+
             return (
               <li key={item.href}>
                 <Link
@@ -62,7 +71,16 @@ export function Sidebar() {
                   )}
                 >
                   <item.icon className="h-4 w-4" />
-                  {item.label}
+                  <span className="flex-1">{item.label}</span>
+                  {showUnreadDot && (
+                    <span
+                      aria-label={`${totalUnread} unread conversation${totalUnread === 1 ? "" : "s"}`}
+                      className="relative flex h-2 w-2"
+                    >
+                      <span className="absolute inline-flex h-full w-full animate-ping rounded-full bg-emerald-400 opacity-75" />
+                      <span className="relative inline-flex h-2 w-2 rounded-full bg-emerald-500" />
+                    </span>
+                  )}
                 </Link>
               </li>
             );

src/hooks/use-total-unread.ts

@@ -0,0 +1,74 @@
+"use client";
+
+import { useEffect, useRef, useState } from "react";
+import { createClient } from "@/lib/supabase/client";
+import type { Conversation } from "@/types";
+
+/**
+ * Count of conversations with at least one unread inbound message for
+ * the current user. Used by the sidebar to surface a green dot on the
+ * Inbox nav entry when the user is elsewhere in the app.
+ *
+ * Lives on its own realtime channel (distinct from the inbox page's
+ * "inbox-realtime") so both can coexist without sharing state.
+ */
+export function useTotalUnread(): number {
+  const [total, setTotal] = useState(0);
+
+  // Keep a live local mirror of {id: unread_count} so INSERT/UPDATE/DELETE
+  // events can adjust the total in O(1) without refetching.
+  const countsRef = useRef<Map<string, number>>(new Map());
+
+  useEffect(() => {
+    const supabase = createClient();
+    let cancelled = false;
+
+    // Initial load. RLS scopes this to the signed-in user automatically —
+    // no explicit user_id filter needed here.
+    (async () => {
+      const { data, error } = await supabase
+        .from("conversations")
+        .select("id, unread_count");
+      if (cancelled || error || !data) return;
+
+      const map = new Map<string, number>();
+      let sum = 0;
+      for (const row of data as { id: string; unread_count: number }[]) {
+        const n = row.unread_count ?? 0;
+        map.set(row.id, n);
+        if (n > 0) sum += 1;
+      }
+      countsRef.current = map;
+      setTotal(sum);
+    })();
+
+    const channel = supabase
+      .channel("total-unread-realtime")
+      .on(
+        "postgres_changes",
+        { event: "*", schema: "public", table: "conversations" },
+        (payload) => {
+          const map = countsRef.current;
+          if (payload.eventType === "DELETE") {
+            const oldRow = payload.old as Partial<Conversation>;
+            if (oldRow.id) map.delete(oldRow.id);
+          } else {
+            const row = payload.new as Conversation;
+            map.set(row.id, row.unread_count ?? 0);
+          }
+          // Recompute — cheap, conversations per user stay small.
+          let sum = 0;
+          for (const n of map.values()) if (n > 0) sum += 1;
+          setTotal(sum);
+        },
+      )
+      .subscribe();
+
+    return () => {
+      cancelled = true;
+      supabase.removeChannel(channel);
+    };
+  }, []);
+
+  return total;
+}