diff --git a/app/src/components/layout/NotesDock.test.tsx b/app/src/components/layout/NotesDock.test.tsx
index d825eb3..ceaee6d 100644
--- a/app/src/components/layout/NotesDock.test.tsx
+++ b/app/src/components/layout/NotesDock.test.tsx
@@ -95,4 +95,19 @@ describe("NotesDock", () => {
     fireEvent.keyDown(handle, { key: "ArrowLeft" });
     expect(state.setNotesDockWidth).toHaveBeenCalled();
   });
+
+  it("widens on ArrowLeft and narrows on ArrowRight, by the exact step", () => {
+    // The dock sits on the right edge, so dragging or pressing left grows it
+    // and right shrinks it. Asserting only "was called" would pass even if
+    // the branches were swapped or the sign inverted.
+    state.activeTabKey = "home:p1";
+    render(<NotesDock />);
+    const handle = screen.getByRole("separator", { name: /resize notes/i });
+
+    fireEvent.keyDown(handle, { key: "ArrowLeft" });
+    expect(state.setNotesDockWidth).toHaveBeenLastCalledWith(368);
+
+    fireEvent.keyDown(handle, { key: "ArrowRight" });
+    expect(state.setNotesDockWidth).toHaveBeenLastCalledWith(336);
+  });
 });
diff --git a/app/src/store/dockWidth.test.ts b/app/src/store/dockWidth.test.ts
index 9bb0361..1a0e066 100644
--- a/app/src/store/dockWidth.test.ts
+++ b/app/src/store/dockWidth.test.ts
@@ -1,4 +1,4 @@
-import { describe, it, expect } from "vitest";
+import { describe, it, expect, afterEach, vi } from "vitest";
 import {
   clampDockWidth,
   NOTES_DOCK_MIN_WIDTH,
@@ -29,3 +29,34 @@ describe("clampDockWidth", () => {
     expect(clampDockWidth(400.6)).toBe(401);
   });
 });
+
+// The pure function above is only half the contract: the brief calls out that
+// the clamp must guard the *read* path too, because localStorage can carry
+// anything a previous version, a hand edit, or a different screen left
+// behind. These tests exercise the real store initialization — seeding
+// localStorage, then re-importing the module fresh so its top-level
+// `loadNotesDockWidth()` call runs against the seeded value — rather than a
+// function pulled out just to make this testable. A future refactor that
+// dropped the clamp from the load path while keeping it on the write path
+// would fail these.
+describe("notesDockWidth store initialization", () => {
+  const WIDTH_KEY = "triple-c.notes.dock.width";
+
+  afterEach(() => {
+    localStorage.removeItem(WIDTH_KEY);
+  });
+
+  it("clamps an out-of-range stored value on load", async () => {
+    localStorage.setItem(WIDTH_KEY, "99999");
+    vi.resetModules();
+    const { useAppState } = await import("./appState");
+    expect(useAppState.getState().notesDockWidth).toBe(NOTES_DOCK_MAX_WIDTH);
+  });
+
+  it("falls back to the default for a non-numeric stored value on load", async () => {
+    localStorage.setItem(WIDTH_KEY, "banana");
+    vi.resetModules();
+    const { useAppState } = await import("./appState");
+    expect(useAppState.getState().notesDockWidth).toBe(NOTES_DOCK_DEFAULT_WIDTH);
+  });
+});