1 files changed, 69 insertions, 0 deletions
diff --git a/packages/app/src/context/layout.test.ts b/packages/app/src/context/layout.test.ts
new file mode 100644
index 000000000..582d5edbd
--- /dev/null
+++ b/packages/app/src/context/layout.test.ts
@@ -0,0 +1,69 @@
+import { describe, expect, test } from "bun:test"
+import { createRoot, createSignal } from "solid-js"
+import { createSessionKeyReader, ensureSessionKey, pruneSessionKeys } from "./layout"
+
+describe("layout session-key helpers", () => {
+  test("couples touch and scroll seed in order", () => {
+    const calls: string[] = []
+    const result = ensureSessionKey(
+      "dir/a",
+      (key) => calls.push(`touch:${key}`),
+      (key) => calls.push(`seed:${key}`),
+    )
+
+    expect(result).toBe("dir/a")
+    expect(calls).toEqual(["touch:dir/a", "seed:dir/a"])
+  })
+
+  test("reads dynamic accessor keys lazily", () => {
+    const seen: string[] = []
+
+    createRoot((dispose) => {
+      const [key, setKey] = createSignal("dir/one")
+      const read = createSessionKeyReader(key, (value) => seen.push(value))
+
+      expect(read()).toBe("dir/one")
+      setKey("dir/two")
+      expect(read()).toBe("dir/two")
+
+      dispose()
+    })
+
+    expect(seen).toEqual(["dir/one", "dir/two"])
+  })
+})
+
+describe("pruneSessionKeys", () => {
+  test("keeps active key and drops lowest-used keys", () => {
+    const drop = pruneSessionKeys({
+      keep: "k4",
+      max: 3,
+      used: new Map([
+        ["k1", 1],
+        ["k2", 2],
+        ["k3", 3],
+        ["k4", 4],
+      ]),
+      view: ["k1", "k2", "k4"],
+      tabs: ["k1", "k3", "k4"],
+    })
+
+    expect(drop).toEqual(["k1"])
+    expect(drop.includes("k4")).toBe(false)
+  })
+
+  test("does not prune without keep key", () => {
+    const drop = pruneSessionKeys({
+      keep: undefined,
+      max: 1,
+      used: new Map([
+        ["k1", 1],
+        ["k2", 2],
+      ]),
+      view: ["k1"],
+      tabs: ["k2"],
+    })
+
+    expect(drop).toEqual([])
+  })
+})