message grouping + date separators + linkified URLs

- Consecutive same-sender messages within 5min collapse (compact mode)
- Compact: no avatar/name/badges, aligned to content area, minimal padding
- Date separators with horizontal lines between days
- URLs auto-linkified in orange with underline
- Links open in new tab, stopPropagation to not trigger select

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

ui/colony/src/App.tsx

@@ -206,32 +206,53 @@ export default function App() {
               no messages yet — start typing below
             </div>
           ) : (
-            messages.map((msg) => (
-              <MessageItem
-                key={msg.id}
-                message={msg}
-                replyTarget={msg.reply_to ? messagesById.get(msg.reply_to) : undefined}
-                currentUsername={getCurrentUsername()}
-                selected={selectedMessages.some((s) => s.id === msg.id)}
-                onSelect={(id) => {
-                  setSelectedMessages((prev) => {
-                    const exists = prev.find((s) => s.id === id);
-                    if (exists) return prev.filter((s) => s.id !== id);
-                    const target = messagesById.get(id);
-                    if (!target) return prev;
-                    return [...prev, { id, username: target.user.display_name, content: target.content }];
-                  });
-                }}
-                onDelete={async (chId, msgId) => {
-                  try {
-                    await deleteMessage(chId, msgId);
-                    loadMessages();
-                  } catch {
-                    // ignore
-                  }
-                }}
-              />
-            ))
+            messages.map((msg, i) => {
+              const prev = i > 0 ? messages[i - 1] : null;
+              const sameSender = prev && prev.user.username === msg.user.username;
+              const withinWindow = prev && (new Date(msg.created_at).getTime() - new Date(prev.created_at).getTime()) < 5 * 60 * 1000;
+              const compact = !!(sameSender && withinWindow && !msg.reply_to);
+              const prevDate = prev ? new Date(prev.created_at).toDateString() : null;
+              const thisDate = new Date(msg.created_at).toDateString();
+              const showDate = prevDate !== thisDate;
+
+              return (
+                <div key={msg.id}>
+                  {showDate && (
+                    <div className="flex items-center gap-3 px-5 py-3">
+                      <div className="flex-1 h-px bg-border" />
+                      <span className="text-[10px] font-mono text-muted-foreground uppercase tracking-widest">
+                        {new Date(msg.created_at).toLocaleDateString("en-US", { weekday: "short", month: "short", day: "numeric" })}
+                      </span>
+                      <div className="flex-1 h-px bg-border" />
+                    </div>
+                  )}
+                  <MessageItem
+                    message={msg}
+                    compact={compact}
+                    replyTarget={msg.reply_to ? messagesById.get(msg.reply_to) : undefined}
+                    currentUsername={getCurrentUsername()}
+                    selected={selectedMessages.some((s) => s.id === msg.id)}
+                    onSelect={(id) => {
+                      setSelectedMessages((prevSel) => {
+                        const exists = prevSel.find((s) => s.id === id);
+                        if (exists) return prevSel.filter((s) => s.id !== id);
+                        const target = messagesById.get(id);
+                        if (!target) return prevSel;
+                        return [...prevSel, { id, username: target.user.display_name, content: target.content }];
+                      });
+                    }}
+                    onDelete={async (chId, msgId) => {
+                      try {
+                        await deleteMessage(chId, msgId);
+                        loadMessages();
+                      } catch {
+                        // ignore
+                      }
+                    }}
+                  />
+                </div>
+              );
+            })
           )}
         </ScrollArea>
 

ui/colony/src/components/MessageItem.tsx

@@ -7,6 +7,7 @@ import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "@/comp
 
 interface Props {
   message: Message;
+  compact?: boolean;
   replyTarget?: Message;
   onSelect: (id: string) => void;
   onDelete: (channelId: string, msgId: string) => void;
@@ -33,8 +34,8 @@ function timeAgo(dateStr: string): string {
 }
 
 function renderContent(text: string) {
-  // Split on @mentions and render them as highlighted spans
-  const parts = text.split(/(@[\w-]+)/g);
+  // Split on @mentions and URLs
+  const parts = text.split(/((?:https?:\/\/)[^\s]+|@[\w-]+)/g);
   return parts.map((part, i) => {
     if (part.startsWith("@")) {
       return (
@@ -43,6 +44,20 @@ function renderContent(text: string) {
         </span>
       );
     }
+    if (part.startsWith("http://") || part.startsWith("https://")) {
+      return (
+        <a
+          key={i}
+          href={part}
+          target="_blank"
+          rel="noopener noreferrer"
+          onClick={(e) => e.stopPropagation()}
+          className="text-primary underline underline-offset-2 hover:text-primary/80"
+        >
+          {part}
+        </a>
+      );
+    }
     return part;
   });
 }
@@ -56,7 +71,7 @@ function userHue(username: string): number {
   return Math.abs(hash) % 360;
 }
 
-export function MessageItem({ message, replyTarget, onSelect, onDelete, currentUsername, selected }: Props) {
+export function MessageItem({ message, compact, replyTarget, onSelect, onDelete, currentUsername, selected }: Props) {
   const [metaOpen, setMetaOpen] = useState(false);
   const isAgent = message.user.role === "agent";
   const isDeleted = !!message.deleted_at;
@@ -77,7 +92,8 @@ export function MessageItem({ message, replyTarget, onSelect, onDelete, currentU
       id={`msg-${message.id}`}
       onClick={() => onSelect(message.id)}
       className={cn(
-        "group relative border-b border-border/50 border-l-4 transition-all duration-300 cursor-pointer",
+        "group relative border-l-4 transition-all duration-300 cursor-pointer",
+        compact ? "" : "border-b border-border/50",
         cfg.border,
         selected ? "!border-l-primary bg-primary/5" : isAgent ? "bg-card" : "bg-background",
         "hover:bg-muted/30",
@@ -96,9 +112,9 @@ export function MessageItem({ message, replyTarget, onSelect, onDelete, currentU
         </button>
       )}
 
-      <div className="px-4 py-3 md:px-5 md:py-4">
-        {/* Header */}
-        <div className="flex items-center gap-2.5 text-[11px] flex-wrap">
+      <div className={cn("px-4 md:px-5", compact ? "py-0.5 pl-[52px] md:pl-[56px]" : "py-3 md:py-4")}>
+        {/* Header — hidden in compact mode */}
+        {!compact && <div className="flex items-center gap-2.5 text-[11px] flex-wrap">
           {/* Avatar — ape emoji with OKLCH color, agents get first letter */}
           <Avatar size="sm" className="rounded-none">
             <AvatarFallback
@@ -151,7 +167,7 @@ export function MessageItem({ message, replyTarget, onSelect, onDelete, currentU
             </Tooltip>
           </TooltipProvider>
 
-        </div>
+        </div>}
 
         {/* Floating action pill — top-right, appears on hover */}
         <div className="absolute -top-3 right-3 md:opacity-0 md:translate-y-1 md:group-hover:opacity-100 md:group-hover:translate-y-0 transition-all duration-150 flex border-2 border-border bg-card shadow-lg z-10">