feat(app-headless-cms): headless (code-based) CMS bulk actions — phase 1

[adrians5j]

What

A code-based ("headless") admin API for Headless CMS bulk actions. Today a custom entry-list bulk action needs ~4 hand-written admin files (button component, websocket handler, createFeature, registration). This adds a CmsBulkAction DI abstraction so the whole thing is one class — implement + createImplementation, mirroring the API-side EntriesBulkAction. No hand-written React.

This is Phase 1 (the non-form path). Phase 2 adds the buildForm (FormModel) dialog path.

API

class ApplyDiscountBulkAction implements CmsBulkAction.Interface<ApplyDiscountData> {
  readonly name = "applyDiscount";
  readonly modelIds = ["product"];
  readonly icon = "discount";                 // IconRegistry key (or a React element)
  button() { return { text: "Apply -10%" }; }
  confirm(ctx) { return { title, message, loadingLabel }; }
  buildData() { return { percent: 10 }; }
  readonly notifications = { "cms.product.discountApplied": d => ({ variant, title, description }) };
}
export default CmsBulkAction.createImplementation({ implementation: ApplyDiscountBulkAction, dependencies: [] });

The framework renders the toolbar BulkActionButton, resolves the icon, computes the selection where (allSelected ? undefined : { id_in }), opens the confirm dialog, triggers BulkActionFeature (action = PascalCased name), deselects, toasts, and generates one WebsocketEventHandler per notifications key.

Changes

• CmsBulkAction abstraction → exported from webiny/admin/cms/entry/list. Form path (formTitle/buildForm) marked TODO(phase 2).
• IconRegistry DI feature + registerIcon (string key → @webiny/icons component, tree-shake-friendly; also accepts a raw element) → exported from webiny/admin.
• Generated toolbar button + registrar (resolves all registered CmsBulkAction impls into ContentEntryListConfig.Browser.BulkAction) + per-notification handler factory.
• applyDiscount demo migrated: 3 admin files → 1 class (−122 lines).
• AGENTS.md: no inline object types for params/returns — use a named interface.

Notes / decisions

• One impl = one toolbar button (single button()), not actions(): Action[].
• Registrar resolves in a post-commit useEffect (snapshot of resolveAll). Works for synchronously-registered extensions (the norm); lazy/async-registered actions after first commit would be missed — worth revisiting if lazy extensions land.
• Success ("task started") toast is a framework default — the abstraction has no field for it yet; a startToast? could be added if we want it authored.
• Admin-only; layered on 6.5.0's public BulkActionFeature/BulkActionButton/useBulkActionDialog. No API-side changes.
• Both @webiny/app-admin and @webiny/app-headless-cms build green; lint clean.

Follow-ups

• Phase 2: buildForm(form, ctx) FormModel dialog path (formTitle() for title/submit label; ctx.values from the built form) + migrate the aiContent demo (persona/project select fields).

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