fix subcommands in json model

bin/main.ml

@@ -364,7 +364,7 @@ let help_resolve_par ?(timeout=200) cmd rest name =
                else
                  let at_limit = q_depth >= 5 in
                  let subs = if at_limit then [] else r.subcommands in
-                 Some ({ r with subcommands = [] }, subs)) in
+                 Some (r, subs)) in
         let oc = Unix.out_channel_of_descr wr in
         Marshal.to_channel oc (result : (help_result * subcommand list) option) [];
         close_out oc;
@@ -613,10 +613,13 @@ let cmd_complete spans user_dir system_dirs =
        if String.starts_with ~prefix:"-" partial then
          candidates := flag_completions partial r.entries
        else begin
+         let subs = match r.subcommands with
+           | _ :: _ -> r.subcommands
+           | [] -> subcommands_of dirs _matched_name in
          List.iter (fun (sc : subcommand) ->
            if partial = "" || String.starts_with ~prefix:partial sc.name then
              candidates := completion_json sc.name sc.desc :: !candidates
-         ) r.subcommands;
+         ) subs;
          candidates := List.rev !candidates;
          if partial = "" || !candidates = [] then
            candidates := !candidates @ flag_completions partial r.entries

lib/store.ml

@@ -308,6 +308,34 @@ let lookup_raw dirs command =
 let has_command dirs command =
   find_file dirs command <> None
 
+let subcommands_of dirs command =
+  let prefix = filename_of_command command ^ "_" in
+  let plen = String.length prefix in
+  let module SMap = Map.Make(String) in
+  let subs = ref SMap.empty in
+  List.iter (fun dir ->
+    if Sys.file_exists dir && Sys.is_directory dir then
+      Array.iter (fun f ->
+        if String.starts_with ~prefix f then
+          let base =
+            if Filename.check_suffix f ".json" then
+              Some (Filename.chop_suffix f ".json")
+            else if Filename.check_suffix f ".nu" then
+              Some (Filename.chop_suffix f ".nu")
+            else None in
+          match base with
+          | Some b ->
+            let rest = String.sub b plen (String.length b - plen) in
+            (* Only direct children: no further underscores *)
+            if not (String.contains rest '_') && String.length rest > 0 then
+              let name = rest in
+              if not (SMap.mem name !subs) then
+                subs := SMap.add name { name; desc = "" } !subs
+          | None -> ()
+      ) (Sys.readdir dir)
+  ) dirs;
+  SMap.fold (fun _ sc acc -> sc :: acc) !subs [] |> List.rev
+
 let all_commands dirs =
   let module SSet = Set.Make(String) in
   let cmds = ref SSet.empty in