CUSTOM custom views (React + classic) — phase 4 (tracking)

[AlexKirkouski]

Tracking issue for the next wave of work on custom form views — both the React custom container (a container whose custom attribute is a component name, e.g. custom = 'OrderApp') and the classic group-object CUSTOM view.

Today the React custom view receives property values only, while the classic view already surfaces much presentation through its controller getters — so the two paths have diverged. This phase brings the React projection up to full fidelity, adds capabilities both paths lack, and re-aligns the React and classic controllers.

All items below extend the same custom-view surface and are tracked together here. They can land incrementally and largely independently.

Subtasks

• CUSTOM REACT: expose per-cell loading and form/action pending state (reactively, via data) #1669 — Per-cell loading/pending (+ global in-flight indicator via a hook, not a prop)
• CUSTOM REACT: project the full property presentation (captions, read-only, colors, classes, images, sums) #1670 — Full property presentation in the React projection (captions, read-only, colors, classes, images, sums)
• CUSTOM custom views: localization access for custom components #1671 — Localization access for custom components
• CUSTOM custom views: support tree (hierarchical) group objects #1672 — Tree (hierarchical) group objects
• CUSTOM custom views: container collapse/active state, and correct data for collapsed/inactive-tab views #1673 — Container collapse/active state + correct data for collapsed/inactive-tab views
• CUSTOM REACT: embed native lsFusion components inside a React container #1674 — Embed native lsFusion components inside a React container
• CUSTOM custom views: expand and align the controller API (filters, orders, totals, reports/export, expand, view mode) #1675 — Expand and align the controller API (filters, orders, totals, reports/export, expand, view mode)
• CUSTOM REACT: support column-group properties in the projection #1676 — Column-group properties in the React projection
• CUSTOM REACT: incremental large-list rendering in window.lsfusion.List (stable keys + per-row subscription) #1677 — Incremental large-list rendering in window.lsfusion.List (stable keys + per-row subscription, no app-level memo; not solvable by React Compiler)

Notes

• Loading + presentation (CUSTOM REACT: expose per-cell loading and form/action pending state (reactively, via data) #1669, CUSTOM REACT: project the full property presentation (captions, read-only, colors, classes, images, sums) #1670) share a common data-channel decision (kept open until those are implemented).
• A recurring goal across items: the React and classic custom controllers should converge so a component is portable between them.

[AlexKirkouski]

Scope note: the async-state surface should land as one unit here — both the form-level pending / busy indicator (whether the form has in-flight requests) and per-property/cell loading state (which specific cells are awaiting a server value). A React component needs both to faithfully reflect async activity: a global busy indicator plus per-cell loading placeholders. So pending and loading belong together as part of this issue.

[AlexKirkouski]

Update: the form-level pending indicator has since been removed from the initial surface entirely (it was briefly exposed through a hook). The initial customReact contract is now strictly values-only: the component receives the projected property values (plus the row key / current-row flag) and the mutation controller — no async state at all.

So this issue now owns the whole async-state surface from scratch: form-level pending (in-flight requests) together with per-property/cell loading, designed as one unit. One design constraint learned from the interim implementation: the pending indicator must not be delivered as a root component prop — it changes on every request start/finish independently of the data, which forces a full re-render of the component tree on each request; it belongs in the subscription/selector surface alongside loading.