feat: execute slash commands immediately on autocomplete selection

When selecting a slash command from the autocomplete menu, the action
now executes immediately and clears the input, providing a more
streamlined UX.

Changes:
- Added onCommandExecute prop to MentionEditor
- Modified slash command suggestion to call onCommandExecute on selection
- Clears editor content immediately after selection
- Added handleCommandExecute callback in ChatViewer
- Executes action and shows toast notifications

Before: Type "/" → select "/join" → press Enter → executes
After: Type "/" → select "/join" → executes immediately

This matches the expected behavior for command selection - when you
choose a command from autocomplete, you want to execute it, not just
insert it into the text field.

Tests: All 804 tests passing
Build: Successful
Lint: No new errors

src/components/ChatViewer.tsx

@@ -18,6 +18,7 @@ import { Nip29Adapter } from "@/lib/chat/adapters/nip-29-adapter";
 import { Nip53Adapter } from "@/lib/chat/adapters/nip-53-adapter";
 import type { ChatProtocolAdapter } from "@/lib/chat/adapters/base-adapter";
 import type { Message } from "@/types/chat";
+import type { ChatAction } from "@/types/chat-actions";
 import { parseSlashCommand } from "@/lib/chat/slash-command-parser";
 import { UserName } from "./nostr/UserName";
 import { RichText } from "./nostr/RichText";
@@ -497,6 +498,36 @@ export function ChatViewer({
     }
   };
 
+  // Handle command execution from autocomplete
+  const handleCommandExecute = useCallback(
+    async (action: ChatAction) => {
+      if (!conversation || !hasActiveAccount || isSending) return;
+
+      setIsSending(true);
+      try {
+        const result = await adapter.executeAction(action.name, {
+          activePubkey: activeAccount.pubkey,
+          activeSigner: activeAccount.signer,
+          conversation,
+        });
+
+        if (result.success) {
+          toast.success(result.message || "Action completed");
+        } else {
+          toast.error(result.message || "Action failed");
+        }
+      } catch (error) {
+        console.error("[Chat] Failed to execute action:", error);
+        const errorMessage =
+          error instanceof Error ? error.message : "Action failed";
+        toast.error(errorMessage);
+      } finally {
+        setIsSending(false);
+      }
+    },
+    [conversation, hasActiveAccount, isSending, adapter, activeAccount],
+  );
+
   // Handle reply button click
   const handleReply = useCallback((messageId: string) => {
     setReplyTo(messageId);
@@ -813,6 +844,7 @@ export function ChatViewer({
               searchProfiles={searchProfiles}
               searchEmojis={searchEmojis}
               searchCommands={searchCommands}
+              onCommandExecute={handleCommandExecute}
               onSubmit={(content, emojiTags) => {
                 if (content.trim()) {
                   handleSend(content, replyTo, emojiTags);

src/components/editor/MentionEditor.tsx

@@ -56,6 +56,7 @@ export interface MentionEditorProps {
   searchProfiles: (query: string) => Promise<ProfileSearchResult[]>;
   searchEmojis?: (query: string) => Promise<EmojiSearchResult[]>;
   searchCommands?: (query: string) => Promise<ChatAction[]>;
+  onCommandExecute?: (action: ChatAction) => Promise<void>;
   autoFocus?: boolean;
   className?: string;
 }
@@ -159,6 +160,7 @@ export const MentionEditor = forwardRef<
       searchProfiles,
       searchEmojis,
       searchCommands,
+      onCommandExecute,
       autoFocus = false,
       className = "",
     },
@@ -620,15 +622,17 @@ export const MentionEditor = forwardRef<
               ...slashCommandSuggestion,
               command: ({ editor, props }: any) => {
                 // props is the ChatAction
-                // Replace the entire content with just the command
-                editor
-                  .chain()
-                  .focus()
-                  .deleteRange({ from: 0, to: editor.state.doc.content.size })
-                  .insertContentAt(0, [
-                    { type: "text", text: `/${props.name}` },
-                  ])
-                  .run();
+                // Execute the command immediately and clear the editor
+                editor.commands.clearContent();
+                if (onCommandExecute) {
+                  // Execute action asynchronously
+                  onCommandExecute(props).catch((error) => {
+                    console.error(
+                      "[MentionEditor] Command execution failed:",
+                      error,
+                    );
+                  });
+                }
               },
             },
             renderLabel({ node }) {
@@ -643,6 +647,7 @@ export const MentionEditor = forwardRef<
       mentionSuggestion,
       emojiSuggestion,
       slashCommandSuggestion,
+      onCommandExecute,
       placeholder,
     ]);