1 files changed, 55 insertions, 0 deletions
diff --git a/src/features/views/logic/panels.test.ts b/src/features/views/logic/panels.test.ts
new file mode 100644
index 0000000..aadbf5e
--- /dev/null
+++ b/src/features/views/logic/panels.test.ts
@@ -0,0 +1,55 @@
+import { describe, expect, it } from "vitest";
+import { addPanel, initialPanels, removePanel, selectKind } from "./panels";
+
+describe("view panels reducer", () => {
+  it("seeds one empty panel by default", () => {
+    const s = initialPanels();
+    expect(s.panels).toHaveLength(1);
+    expect(s.panels[0]?.kind).toBeNull();
+  });
+
+  it("seeds a panel per provided kind, in order, with unique ids", () => {
+    const s = initialPanels(["surfaces", null]);
+    expect(s.panels.map((p) => p.kind)).toEqual(["surfaces", null]);
+    expect(new Set(s.panels.map((p) => p.id)).size).toBe(2);
+  });
+
+  it("addPanel appends an empty panel with a fresh id", () => {
+    const seed = initialPanels(["surfaces"]);
+    const s = addPanel(seed);
+    expect(s.panels).toHaveLength(2);
+    expect(s.panels[1]?.kind).toBeNull();
+    expect(s.panels[1]?.id).not.toBe(s.panels[0]?.id);
+  });
+
+  it("addPanel can seed a kind", () => {
+    const s = addPanel(initialPanels([null]), "surfaces");
+    expect(s.panels[1]?.kind).toBe("surfaces");
+  });
+
+  it("removePanel drops the matching id only", () => {
+    const seed = initialPanels(["surfaces", null]);
+    const firstId = seed.panels[0]?.id ?? -1;
+    const s = removePanel(seed, firstId);
+    expect(s.panels).toHaveLength(1);
+    expect(s.panels[0]?.kind).toBeNull();
+  });
+
+  it("selectKind updates only the targeted panel", () => {
+    const seed = initialPanels([null, null]);
+    const targetId = seed.panels[1]?.id ?? -1;
+    const s = selectKind(seed, targetId, "surfaces");
+    expect(s.panels[0]?.kind).toBeNull();
+    expect(s.panels[1]?.kind).toBe("surfaces");
+  });
+
+  it("is pure — never mutates the input state", () => {
+    const seed = initialPanels(["surfaces"]);
+    const snapshot = JSON.stringify(seed);
+    const id = seed.panels[0]?.id ?? -1;
+    addPanel(seed);
+    removePanel(seed, id);
+    selectKind(seed, id, null);
+    expect(JSON.stringify(seed)).toBe(snapshot);
+  });
+});