replace send_file_dm with open_dm resolver (per review)

hive-matrix-mcp/src/handlers.rs

@@ -185,7 +185,7 @@ pub async fn send_message(client: &Client, room_ref: &str, body: &str) -> Daemon
 }
 
 /// Find the existing DM room with `user_id` or create one. Shared by
-/// `send_dm` and `send_file_dm`. `direct_targets()` (cached state) is
+/// `send_dm` and `open_dm`. `direct_targets()` (cached state) is
 /// used rather than the async `is_direct()`.
 async fn resolve_or_create_dm(
     client: &Client,
@@ -304,20 +304,19 @@ pub async fn send_file(
     upload_attachment(&room, path, caption).await
 }
 
-pub async fn send_file_dm(
-    client: &Client,
-    user_id: &str,
-    path: &str,
-    caption: Option<&str>,
-) -> DaemonResponse {
+/// Resolve (find-or-create) the DM room with `user_id` and return its
+/// room id without sending anything. The caller then uses the room-based
+/// tools (`send_file`, `send_message`, …) against that id — so there is
+/// no per-tool `_dm` variant.
+pub async fn open_dm(client: &Client, user_id: &str) -> DaemonResponse {
     let room = match resolve_or_create_dm(client, user_id).await {
         Ok(r) => r,
         Err(e) => return e,
     };
-    if let Some(reject) = unread_guard(&room) {
-        return reject;
-    }
-    upload_attachment(&room, path, caption).await
+    DaemonResponse::ok(&serde_json::json!({
+        "room_id": room.room_id().to_string(),
+        "user_id": user_id,
+    }))
 }
 
 pub async fn send_reaction(