delete messages + fix layout overflow

- DELETE /api/channels/{id}/messages/{msg_id} — soft delete, own only
- Broadcasts WsEvent::Delete to subscribers
- UI: "Del" button on hover for own messages (turns red)
- Fix layout: h-full + overflow-hidden on flex containers
- ScrollArea gets min-h-0 to properly constrain in flex
- Messages no longer push compose past viewport

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

crates/colony/src/main.rs

@@ -49,6 +49,10 @@ async fn main() {
             "/api/channels/{channel_id}/messages",
             get(routes::list_messages).post(routes::post_message),
         )
+        .route(
+            "/api/channels/{channel_id}/messages/{msg_id}",
+            axum::routing::delete(routes::delete_message),
+        )
         .route("/ws/{channel_id}", get(ws::ws_handler))
         .fallback_service(
             ServeDir::new("static").fallback(ServeFile::new("static/index.html")),

crates/colony/src/routes.rs

@@ -278,6 +278,47 @@ pub async fn post_message(
     Ok((StatusCode::CREATED, Json(message)))
 }
 
+pub async fn delete_message(
+    State(state): State<AppState>,
+    Path((channel_id, msg_id)): Path<(String, String)>,
+    Query(user_param): Query<UserParam>,
+) -> Result<impl IntoResponse> {
+    let user_id = resolve_user(&state.db, &user_param).await?;
+
+    // Verify message exists and belongs to this user
+    let row = sqlx::query_as::<_, MessageWithUserRow>(
+        "SELECT m.*, u.id as u_id, u.username, u.display_name, u.role, u.created_at as u_created_at \
+         FROM messages m JOIN users u ON m.user_id = u.id WHERE m.id = ? AND m.channel_id = ?",
+    )
+    .bind(&msg_id)
+    .bind(&channel_id)
+    .fetch_optional(&state.db)
+    .await?;
+
+    let row = match row {
+        Some(r) => r,
+        None => return Err(AppError::NotFound("Message not found".into())),
+    };
+
+    if row.user_id != user_id {
+        return Err(AppError::BadRequest("Can only delete your own messages".into()));
+    }
+
+    // Soft delete
+    sqlx::query("UPDATE messages SET deleted_at = strftime('%Y-%m-%dT%H:%M:%SZ', 'now') WHERE id = ?")
+        .bind(&msg_id)
+        .execute(&state.db)
+        .await?;
+
+    // Broadcast delete event
+    let tx = state.get_sender(&channel_id).await;
+    let _ = tx.send(WsEvent::Delete {
+        id: uuid::Uuid::parse_str(&msg_id).unwrap(),
+    });
+
+    Ok(StatusCode::NO_CONTENT)
+}
+
 // ── Joined row type for message + user ──
 
 #[derive(Debug, sqlx::FromRow)]

ui/colony/src/App.tsx

@@ -1,7 +1,7 @@
 import { useCallback, useEffect, useRef, useState } from "react";
 import type { Channel } from "@/types/Channel";
 import type { Message } from "@/types/Message";
-import { getChannels, getMessages, getCurrentUsername } from "@/api";
+import { getChannels, getMessages, getCurrentUsername, deleteMessage } from "@/api";
 import { ChannelSidebar } from "@/components/ChannelSidebar";
 import { MessageItem } from "@/components/MessageItem";
 import { ComposeBox } from "@/components/ComposeBox";
@@ -121,12 +121,12 @@ export default function App() {
   );
 
   return (
-    <div className="flex h-full">
+    <div className="flex h-full overflow-hidden">
-      <div className="hidden md:block">
+      <div className="hidden md:flex md:flex-col md:h-full">
         {sidebar}
       </div>
 
-      <div className="flex-1 flex flex-col min-w-0">
+      <div className="flex-1 flex flex-col min-w-0 h-full overflow-hidden">
         <div className="px-4 py-3 md:px-6 md:py-4 border-b-2 border-border flex items-center gap-3">
           <Sheet open={sheetOpen} onOpenChange={setSheetOpen}>
             <SheetTrigger className="md:hidden p-1 h-8 w-8 text-muted-foreground hover:text-primary font-mono font-bold text-lg">
@@ -155,7 +155,7 @@ export default function App() {
           )}
         </div>
 
-        <ScrollArea ref={scrollRef} className="flex-1">
+        <ScrollArea ref={scrollRef} className="flex-1 min-h-0">
           {loading && messages.length === 0 ? (
             <div className="p-5 space-y-4">
               {[1, 2, 3].map((i) => (
@@ -178,12 +178,21 @@ export default function App() {
                 key={msg.id}
                 message={msg}
                 replyTarget={msg.reply_to ? messagesById.get(msg.reply_to) : undefined}
+                currentUsername={getCurrentUsername()}
                 onReply={(id) => {
                   const target = messagesById.get(id);
                   if (target) {
                     setReplyTo({ id, username: target.user.display_name, content: target.content });
                   }
                 }}
+                onDelete={async (chId, msgId) => {
+                  try {
+                    await deleteMessage(chId, msgId);
+                    loadMessages();
+                  } catch {
+                    // ignore
+                  }
+                }}
               />
             ))
           )}

ui/colony/src/api.ts

@@ -74,3 +74,14 @@ export async function postMessage(
     }),
   );
 }
+
+export async function deleteMessage(
+  channelId: string,
+  msgId: string,
+): Promise<void> {
+  const res = await fetch(
+    `${BASE}/channels/${channelId}/messages/${msgId}?${userQuery()}`,
+    { method: "DELETE" },
+  );
+  if (!res.ok) throw new Error(`${res.status}: ${await res.text()}`);
+}

ui/colony/src/components/MessageItem.tsx

@@ -9,6 +9,8 @@ interface Props {
   message: Message;
   replyTarget?: Message;
   onReply: (id: string) => void;
+  onDelete: (channelId: string, msgId: string) => void;
+  currentUsername: string;
 }
 
 const TYPE_CONFIG: Record<string, { border: string; label: string; labelBg: string }> = {
@@ -53,7 +55,7 @@ function userHue(username: string): number {
   return Math.abs(hash) % 360;
 }
 
-export function MessageItem({ message, replyTarget, onReply }: Props) {
+export function MessageItem({ message, replyTarget, onReply, onDelete, currentUsername }: Props) {
   const [metaOpen, setMetaOpen] = useState(false);
   const isAgent = message.user.role === "agent";
   const isDeleted = !!message.deleted_at;
@@ -147,14 +149,25 @@ export function MessageItem({ message, replyTarget, onReply }: Props) {
             </Tooltip>
           </TooltipProvider>
 
-          {/* Reply button */}
+          {/* Actions */}
+          <div className="ml-auto flex items-center gap-1 md:opacity-0 md:group-hover:opacity-100 transition-opacity">
             <button
               type="button"
               onClick={() => onReply(message.id)}
-            className="font-sans text-[10px] font-bold uppercase tracking-wider text-muted-foreground md:opacity-0 md:group-hover:opacity-60 hover:!text-primary transition-all ml-auto min-w-[44px] min-h-[44px] md:min-w-0 md:min-h-0 flex items-center justify-end"
+              className="font-sans text-[10px] font-bold uppercase tracking-wider text-muted-foreground hover:text-primary min-w-[44px] min-h-[44px] md:min-w-0 md:min-h-0 flex items-center justify-center"
             >
               Reply
             </button>
+            {!isDeleted && message.user.username === currentUsername && (
+              <button
+                type="button"
+                onClick={() => onDelete(message.channel_id, message.id)}
+                className="font-sans text-[10px] font-bold uppercase tracking-wider text-muted-foreground hover:text-destructive min-w-[44px] min-h-[44px] md:min-w-0 md:min-h-0 flex items-center justify-center"
+              >
+                Del
+              </button>
+            )}
+          </div>
         </div>
 
         {/* Content */}