chore: refactoring and tests, splitting up files (#12495)

packages/app/src/pages/session/use-session-hash-scroll.test.ts

@@ -0,0 +1,16 @@
+import { describe, expect, test } from "bun:test"
+import { messageIdFromHash } from "./use-session-hash-scroll"
+
+describe("messageIdFromHash", () => {
+  test("parses hash with leading #", () => {
+    expect(messageIdFromHash("#message-abc123")).toBe("abc123")
+  })
+
+  test("parses raw hash fragment", () => {
+    expect(messageIdFromHash("message-42")).toBe("42")
+  })
+
+  test("ignores non-message anchors", () => {
+    expect(messageIdFromHash("#review-panel")).toBeUndefined()
+  })
+})