fix(mongodb): support find explain commands

Closes #5619

crates/dbx-web/src/main.rs

@@ -623,6 +623,7 @@ async fn main() {
         .route("/document-store/delete-document", post(routes::document_store::delete_document))
         .route("/mongo/find-documents", post(routes::mongo::find_documents))
         .route("/mongo/parse-shell-command", post(routes::mongo::parse_shell_command))
+        .route("/mongo/explain-find", post(routes::mongo::explain_find))
         .route("/mongo/find-one", post(routes::mongo::find_one))
         .route("/mongo/count-documents", post(routes::mongo::count_documents))
         .route("/mongo/server-version", post(routes::mongo::server_version))

crates/dbx-web/src/routes/mongo.rs

@@ -101,6 +101,22 @@ pub struct MongoFindRequest {
     pub execution_id: Option<String>,
 }
 
+#[derive(Deserialize)]
+#[serde(rename_all = "camelCase")]
+pub struct MongoFindExplainRequest {
+    pub connection_id: String,
+    pub database: String,
+    pub collection: String,
+    pub skip: Option<u64>,
+    pub limit: Option<i64>,
+    pub filter: Option<String>,
+    pub projection: Option<String>,
+    pub sort: Option<String>,
+    pub collation: Option<String>,
+    pub verbosity: Option<String>,
+    pub execution_id: Option<String>,
+}
+
 #[derive(Deserialize)]
 #[serde(rename_all = "camelCase")]
 pub struct MongoFindOneRequest {
@@ -409,6 +425,34 @@ pub async fn find_documents(
     Ok(Json(serde_json::to_value(result).map_err(|e| AppError::from(e.to_string()))?))
 }
 
+pub async fn explain_find(
+    State(state): State<Arc<WebState>>,
+    headers: HeaderMap,
+    Json(req): Json<MongoFindExplainRequest>,
+) -> Result<Json<serde_json::Value>, AppError> {
+    super::mcp_policy::ensure_scope(&state, &headers, &req.connection_id).await?;
+    let verbosity = req.verbosity.as_deref().unwrap_or("queryPlanner");
+    let result = run_cancellable(
+        &state,
+        req.execution_id.clone(),
+        dbx_core::mongo_ops::mongo_explain_find_core(
+            &state.app,
+            &req.connection_id,
+            &req.database,
+            &req.collection,
+            req.skip.unwrap_or(0),
+            req.limit.unwrap_or(100),
+            req.filter.as_deref(),
+            req.projection.as_deref(),
+            req.sort.as_deref(),
+            req.collation.as_deref(),
+            verbosity,
+        ),
+    )
+    .await?;
+    Ok(Json(result))
+}
+
 pub async fn find_one(
     State(state): State<Arc<WebState>>,
     Json(req): Json<MongoFindOneRequest>,