1 files changed, 49 insertions, 0 deletions
diff --git a/src/features/views/logic/panels.ts b/src/features/views/logic/panels.ts
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+++ b/src/features/views/logic/panels.ts
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+/**
+ * Pure reducer for the view sidebar's panel stack.
+ *
+ * A "view" is the RESERVED Dispatch sidebar affordance (see GLOSSARY): the user
+ * stacks panels, each showing one view KIND chosen from a dropdown, and adds
+ * more with a `+` button. This module is the pure model — zero DOM, zero Svelte.
+ * The component (`ViewSidebar.svelte`) is a thin runes wrapper over it.
+ *
+ * `id` is a per-session stable key for `{#each}` only; it is never persisted.
+ */
+
+export interface ViewPanel {
+  readonly id: number;
+  /** Selected view-kind id, or `null` while the panel still reads "Select a view". */
+  readonly kind: string | null;
+}
+
+export interface PanelsState {
+  readonly panels: readonly ViewPanel[];
+  readonly nextId: number;
+}
+
+/**
+ * Seed state. Each entry becomes one panel in order; pass `["surfaces"]` to open
+ * a single preset panel, or `[null]` for one empty "Select a view" panel.
+ */
+export function initialPanels(kinds: readonly (string | null)[] = [null]): PanelsState {
+  let nextId = 0;
+  const panels = kinds.map((kind) => ({ id: nextId++, kind }));
+  return { panels, nextId };
+}
+
+export function addPanel(state: PanelsState, kind: string | null = null): PanelsState {
+  return {
+    panels: [...state.panels, { id: state.nextId, kind }],
+    nextId: state.nextId + 1,
+  };
+}
+
+export function removePanel(state: PanelsState, id: number): PanelsState {
+  return { ...state, panels: state.panels.filter((p) => p.id !== id) };
+}
+
+export function selectKind(state: PanelsState, id: number, kind: string | null): PanelsState {
+  return {
+    ...state,
+    panels: state.panels.map((p) => (p.id === id ? { ...p, kind } : p)),
+  };
+}