fix(ai): preserve host rendering and metadata in grouped tools

ai/transcript.ml

@@ -230,6 +230,20 @@ let tool_card cfg (item_s : item Signal.signal) : t =
       ~accessibility_identifier:"lui-ai-tool"
       [ tool_detail cfg item_s ])
 
+let rendered_body cfg fallback item_s =
+  match cfg.render_item item_s with
+  | Some view -> view
+  | None -> fallback item_s
+
+let grouped_item cfg (item_s : item Signal.signal) : t =
+  scoped (fun _context ->
+    let item = sample item_s in
+    column ~key:item.id ~cross:`stretch
+      ~accessibility_identifier:("lui-ai-item:" ^ item.id)
+      ?style_class:(match cfg.item_class item with "" -> None | value -> Some value)
+      ~data_attrs:(reactive cfg.item_data_attrs item_s)
+      [ rendered_body cfg (tool_card cfg) item_s ])
+
 (* Collapsible section around a run of Tool_call items. Auto-expands
    while any member is active; user toggles persist in row scope. *)
 let tool_group cfg (row_s : row Signal.signal) : t =
@@ -278,7 +292,7 @@ let tool_group cfg (row_s : row Signal.signal) : t =
       ~accessibility_identifier:"lui-ai-tool-group"
       [ column ~cross:`stretch ~gap:6
           [ keyed ~source:items_s ~key:(fun (i : item) -> i.id)
-              ~cmp:String.compare ~mount:(tool_card cfg) ] ])
+              ~cmp:String.compare ~mount:(grouped_item cfg) ] ])
 
 let builtin_body cfg context (item_s : item Signal.signal) : t =
   ignore context;
@@ -295,17 +309,12 @@ let builtin_body cfg context (item_s : item Signal.signal) : t =
 
 let item_row_of cfg context (item_s : item Signal.signal) : t =
   let item = sample item_s in
-  let body =
-    match cfg.render_item item_s with
-    | Some view -> view
-    | None -> builtin_body cfg context item_s
-  in
+  let body = rendered_body cfg (builtin_body cfg context) item_s in
   list_item ~key:item.id ~separator:`hidden
     ~accessibility_identifier:("lui-ai-item:" ^ item.id)
     ?style_class:
       (match cfg.item_class item with "" -> None | s -> Some s)
-    ?data_attrs:
-      (match cfg.item_data_attrs item with [] -> None | l -> Some l)
+    ~data_attrs:(reactive cfg.item_data_attrs item_s)
     [ row ~main:`center ~grow:1.0
         [ column ~grow:1.0 ~max_width:cfg.content_width ~cross:`stretch
             ~padding_horizontal:8 ~padding_vertical:4 [ body ] ] ]

ai/transcript.mli

@@ -63,6 +63,10 @@ val transcript :
       steps" / "Worked through N steps" section ([group_tools], default
       [true]); the section auto-expands while any call is active and
       stays user-toggleable, keyed by the first member's id.
+    - [render_item] is consulted for both single items and grouped tool
+      children. Returning [None] uses the built-in body. Group children keep
+      their item identity and use non-interactive containers, so host tool
+      accordions and controls are not nested inside list-item buttons.
     - [on_retry] adds a resend control on [`uncertain] items (labelled
       [retry_label], default ["Retry same message"]); [item_actions]
       mounts host actions per row (copy, etc.) and receives the borrowed
@@ -74,7 +78,9 @@ val transcript :
       visible (history paging).
     - [container_class]/[container_data_attrs] land on the scroll
       container itself (list or virtual_list) for host CSS/locators;
-      [item_class]/[item_data_attrs] land on each row. *)
+      [item_class]/[item_data_attrs] land on each item, including grouped
+      children. Data attributes update from the current item signal without
+      remounting its body. *)
 
 val item_row : Model.item -> t
 (** A single message row mounted outside [transcript] (previews). *)

docs/agent-guide/proposed/bugfix/2026-10-19-grouped-tool-host-renderer.md

@@ -0,0 +1,71 @@
+# Grouped tool host renderer
+
+## Problem
+
+Transcript single rows use the host item renderer, metadata and styles, but
+grouped tool children call the built-in tool card directly. Enabling work
+grouping therefore loses host-specific tool details and identity attributes.
+
+## Proposal
+
+Route grouped children through a shared host-aware tool rendering helper while
+retaining the built-in card when the host returns None. Preserve keyed child
+identity, borrowed signal ownership, live metadata and the group disclosure
+state. Use an ordinary non-interactive wrapper so tool accordions do not become
+nested buttons. Keep the public API stable and update its documentation.
+
+This is an upstream LUI change, published as a PR before Mapre changes its
+installed package pin. Do not copy library source into the consumer. The user's
+clean composer and full conversation scrolling milestones are now deployed;
+this repair resumes the remaining grouped activity work.
+
+## Alternatives considered
+
+### Replace the consumer transcript
+
+Rejected because it duplicates the library's grouping and lifecycle ownership
+and conflicts with the requested reusable LUI AI integration.
+
+## Acceptance criteria
+
+- Actual mounted component tests reproduce missing host rendering before the
+  fix. Cover custom rendering, default fallback, updated tool content and
+  metadata, keyed child retention, disclosure and disposal without disposing
+  caller-owned signals. Keep pure grouping/order tests intact.
+- Compile native and Melange targets and run the existing relevant test suites.
+  Validate actual browser behavior through the consumer after installation.
+- Keep source functions at most 64 formatted lines. Do not modify Dune files,
+  disable warnings or use unsafe casts. Commit and push, then create the LUI PR.
+- Update Mapre only after upstream review/acceptance and prove its tool details,
+  identities, grouped summaries and scroll behavior in an actual browser.
+
+## Risks
+
+- Grouping can remount children or accidentally dispose their borrowed signals.
+  A native protocol-tree check alone does not establish browser semantics.
+
+## Questions
+
+None. The user explicitly requests grouped work in the UI reference, reuse of
+LUI components, an upstream PR first and no vendoring.
+
+## Verification
+
+Four mounted component regressions fail against the original implementation:
+grouped host rendering, grouped live metadata/callbacks, ordinary live metadata,
+and keyed host lifetime. The shared host-aware body selection and a plain
+group-child column make all four pass. Default tool fallback and output updates
+remain covered; inserting/removing tools preserves child identity and the user's
+disclosure choice. Removed host children dispose once while the caller message
+stream continues to accept changes.
+
+The focused 24-case lui_ai cohort and the complete 147-case test_lui native
+target pass. Melange compilation through @web passes, as does the OCaml AST
+64-line check on the changed source/test modules. No Dune file, warning setting
+or unsafe cast changed. Actual consumer browser acceptance follows publication
+and installed-package review; it is not established by the native checks alone.
+
+The new decision passes its individual check. The repository-wide document check
+still reports two existing legacy paths, 001-implementation-review_report.md
+and 002-review-fixes.md; this change does not rename unrelated historical files
+or claim that repository-wide check passed.

test/test_lui_ai.ml

@@ -186,6 +186,111 @@ let test_tool_group_rendering () =
     (List.exists (( = ) "Worked through 2 steps") (text_nodes s));
   drive_dispose s
 
+let host_attrs (item : M.item) =
+  [ "data-event-id", item.id; "data-current-text", item.text ]
+
+let host_tool ?(on_press = fun _ -> ()) item_s =
+  if (Lui_elements.sample item_s).M.id <> "host" then None
+  else
+    Some
+      (Lui_elements.button ~text:"Host tool details"
+         ~accessibility_identifier:"host-tool-details"
+         ~on_press:(fun _ -> on_press (Lui_elements.get item_s)) [])
+
+let host_transcript ?(group_tools = true) ?on_press () _ctx source _send =
+  Lui_ai.Transcript.transcript ~messages:source ~group_tools
+    ~render_item:(host_tool ?on_press) ~item_data_attrs:host_attrs
+    ~item_class:(fun _ -> "host-item") ()
+
+let test_grouped_host_renderer () =
+  let initial = [ tool_item "host" `in_progress; tool_item "fallback" `pending ] in
+  let s = drive_mount ~initial ~view:(host_transcript ()) in
+  Alcotest.(check bool) "host renderer is used inside the group" true
+    (List.mem "Host tool details" (text_nodes s));
+  Alcotest.(check bool) "default tool renderer remains available" true
+    (List.exists (fun text -> has_sub text "Run fallback") (text_nodes s));
+  let host = find_by_prop s "accessibility-identifier"
+      (StringValue "lui-ai-item:host") in
+  Alcotest.(check string) "group member is a noninteractive container" "column"
+    host.Drive.Model.kind;
+  Alcotest.(check (option string)) "host row class is preserved" (Some "host-item")
+    (match node_prop host "style-class" with Some (StringValue x) -> Some x | _ -> None);
+  Alcotest.(check bool) "host row metadata is preserved" true
+    (match node_prop host "data-attrs" with
+     | Some (StringValue x) -> has_sub x "data-event-id" && has_sub x "host"
+     | _ -> false);
+  drive_dispose s
+
+let test_grouped_host_updates () =
+  let clicked = ref "" in
+  let initial = [ tool_item "host" `in_progress; tool_item "fallback" `in_progress ] in
+  let view = host_transcript ~on_press:(fun item -> clicked := item.M.text) () in
+  let s = drive_mount ~initial ~view in
+  let host () = find_by_prop s "accessibility-identifier"
+      (StringValue "lui-ai-item:host") in
+  let before = (host ()).Drive.Model.id in
+  drive_send_model s (fun items -> M.append_text items "host" "fresh host content");
+  drive_send_model s (fun items ->
+      M.update_tool items (update "fallback" ~output:"fresh default output" ()));
+  Alcotest.(check int) "streaming retains grouped row identity" before (host ()).id;
+  Alcotest.(check bool) "grouped metadata follows the current item" true
+    (match node_prop (host ()) "data-attrs" with
+     | Some (StringValue x) -> has_sub x "fresh host content" | _ -> false);
+  Drive.Session.press s
+    (find_by_prop s "accessibility-identifier" (StringValue "host-tool-details")).id;
+  Alcotest.(check string) "host callback reads current borrowed item"
+    "fresh host content" !clicked;
+  Alcotest.(check bool) "default grouped tool content still updates" true
+    (List.mem "fresh default output" (text_nodes s));
+  drive_dispose s
+
+let test_single_host_metadata_updates () =
+  let initial = [ tool_item "host" `in_progress ] in
+  let s = drive_mount ~initial ~view:(host_transcript ~group_tools:false ()) in
+  let host () = find_by_prop s "accessibility-identifier"
+      (StringValue "lui-ai-item:host") in
+  let before = (host ()).Drive.Model.id in
+  drive_send_model s (fun items -> M.append_text items "host" "new single metadata");
+  Alcotest.(check int) "single row keeps identity" before (host ()).id;
+  Alcotest.(check bool) "single metadata follows the same item contract" true
+    (match node_prop (host ()) "data-attrs" with
+     | Some (StringValue x) -> has_sub x "new single metadata" | _ -> false);
+  drive_dispose s
+
+let test_grouped_host_lifetime () =
+  let mounted = ref 0 and disposed = ref [] in
+  let renderer source =
+    let id = (Lui_elements.sample source).M.id in
+    Some (Lui_elements.scoped (fun context ->
+        incr mounted;
+        Signal.on_dispose context.Lui_ui.ui_scope (fun () -> disposed := id :: !disposed);
+        Lui_elements.button ~text:id ~accessibility_identifier:("host:" ^ id) [])) in
+  let view _ctx source _send =
+    Lui_ai.Transcript.transcript ~messages:source ~render_item:renderer () in
+  let t1 = tool_item "t1" `in_progress and t2 = tool_item "t2" `pending in
+  let s = drive_mount ~initial:[t1;t2] ~view in
+  let group = find_by_prop s "accessibility-identifier"
+      (StringValue "lui-ai-tool-group") in
+  let t2_node = find_by_prop s "accessibility-identifier" (StringValue "host:t2") in
+  Drive.Session.toggle s group.id false;
+  drive_send_model s (fun _ -> [t1;tool_item "t3" `in_progress;t2]);
+  Alcotest.(check int) "group insertion retains custom tool" t2_node.id
+    (find_by_prop s "accessibility-identifier" (StringValue "host:t2")).id;
+  Alcotest.(check bool) "user disclosure survives active updates" true
+    (node_prop group "selected" = Some (BoolValue false));
+  Alcotest.(check int) "only the added custom child mounts" 3 !mounted;
+  drive_send_model s (fun items -> List.filter (fun item -> item.M.id <> "t2") items);
+  Alcotest.(check (list string)) "removed child is disposed once" ["t2"] !disposed;
+  drive_send_model s (fun _ -> []);
+  Alcotest.(check (list string)) "all group children are disposed" ["t1";"t2";"t3"]
+    (List.sort String.compare !disposed);
+  drive_send_model s (fun _ -> [assistant "after" "caller stream remains alive"]);
+  Alcotest.(check bool) "group disposal does not dispose caller source" true
+    (List.mem "after" (text_nodes s));
+  drive_dispose s;
+  Alcotest.(check int) "each mounted host view is disposed exactly once" 4
+    (List.length !disposed)
+
 (* {1 Anchored follow (virtual_list by default)} *)
 
 let test_autoscroll_follow () =
@@ -555,6 +660,10 @@ let tests =
         Alcotest.test_case "reorder/dup identity" `Quick
           test_keyed_reorder_dup;
         Alcotest.test_case "tool group" `Quick test_tool_group_rendering;
+        Alcotest.test_case "grouped host renderer" `Quick test_grouped_host_renderer;
+        Alcotest.test_case "grouped host updates" `Quick test_grouped_host_updates;
+        Alcotest.test_case "single host metadata updates" `Quick test_single_host_metadata_updates;
+        Alcotest.test_case "grouped host lifetime" `Quick test_grouped_host_lifetime;
         Alcotest.test_case "autoscroll follow" `Quick test_autoscroll_follow;
         Alcotest.test_case "reach-top hook" `Quick test_reach_top_hook;
         Alcotest.test_case "host-driven viewport" `Quick