Chart builder: data-aware defaults, one-click hint fixes, canvas preview, fullscreen modal

src/app/modals/modal-registry.ts

@@ -42,6 +42,12 @@ export interface ModalConfig {
   getState?: () => Record<string, unknown> | null;
   /** Whether the modal is reflected in the URL hash (navigable). */
   isUrlNavigable?: boolean;
+  /**
+   * Whether a backdrop (click-outside) closes the modal. Defaults to `true`. Set
+   * `false` for modals holding in-progress work an accidental click shouldn't
+   * discard (the Chart Builder) — Escape and the close button still dismiss.
+   */
+  dismissOnBackdrop?: boolean;
 }
 
 export const MODAL_REGISTRY: Partial<Record<ModalName, ModalConfig>> = {
@@ -71,11 +77,14 @@ export const MODAL_REGISTRY: Partial<Record<ModalName, ModalConfig>> = {
   // Opened from a selected dataset's "Build Chart" action; `arg` is its id. Loads
   // the dataset and pre-populates a smart default config (§06). Applies on Create
   // (a new snippet), so there is nothing transient to lose on close — no getState.
+  // Backdrop dismissal is off: the config is real in-progress work, and a stray
+  // click outside this large surface shouldn't throw it away (Escape/× still close).
   chartBuilder: {
     name: 'chartBuilder',
     title: 'Chart Builder',
     component: ChartBuilderModal,
     isUrlNavigable: true,
+    dismissOnBackdrop: false,
     init: (datasetId) => useChartBuilderStore.getState().init(datasetId ? Number(datasetId) : null),
   },