fix(atlas): skip compaction in last-agent recovery

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-opencode)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/hooks/atlas/session-last-agent.sqlite.test.ts

@@ -0,0 +1,46 @@
+const { describe, expect, mock, test } = require("bun:test")
+
+mock.module("../../shared", () => ({
+  getMessageDir: () => null,
+  isSqliteBackend: () => true,
+  normalizeSDKResponse: <TData>(response: { data?: TData }, fallback: TData): TData => response.data ?? fallback,
+}))
+
+const { getLastAgentFromSession } = await import("./session-last-agent")
+
+function createMockClient(messages: Array<{ info?: { agent?: string } }>) {
+  return {
+    session: {
+      messages: async () => ({ data: messages }),
+    },
+  }
+}
+
+describe("getLastAgentFromSession sqlite branch", () => {
+  test("should skip compaction and return the previous real agent from sqlite messages", async () => {
+    // given
+    const client = createMockClient([
+      { info: { agent: "atlas" } },
+      { info: { agent: "compaction" } },
+    ])
+
+    // when
+    const result = await getLastAgentFromSession("ses_sqlite_compaction", client)
+
+    // then
+    expect(result).toBe("atlas")
+  })
+
+  test("should return null when sqlite history contains only compaction", async () => {
+    // given
+    const client = createMockClient([{ info: { agent: "compaction" } }])
+
+    // when
+    const result = await getLastAgentFromSession("ses_sqlite_only_compaction", client)
+
+    // then
+    expect(result).toBeNull()
+  })
+})
+
+export {}