feat(sp25): extend useMergedTail to handle acks + ta1_acks slices

The Acks page needs two merge hooks (one per ack flavor) and both
shapes use numeric database ids rather than the string ids that
Claim/Remittance/Activity use. The generic constraint widens to
`T extends { id: string | number }` and the dedup Set normalizes
to String(id) so a base item with id=2 and a tail item with id=2
collide correctly.

Adds two switch cases that mirror the claims/remittances keyed-by-id
pattern: iterate the order array, look up the matching value in the
dict, drop undefined holes defensively.

Two tests assert the new slices order by their order arrays and dedup
against base items.

src/hooks/useMergedTail.test.ts

@@ -7,7 +7,7 @@ import { createRoot, type Root } from "react-dom/client";
 import { beforeEach, describe, expect, it } from "vitest";
 import { useMergedTail } from "./useMergedTail";
 import { useTailStore } from "@/store/tail-store";
-import type { Claim, Remittance, Activity } from "@/types";
+import type { Ack, Claim, Remittance, Activity, Ta1Ack } from "@/types";
 
 /**
  * Same `renderHook` shim used in `useClaimDetail`, `useDrawerUrlState`,
@@ -88,6 +88,34 @@ function activity(id: string, message: string): Activity {
   };
 }
 
+function ack(id: number, sourceBatchId: string): Ack {
+  return {
+    id,
+    sourceBatchId,
+    acceptedCount: 1,
+    rejectedCount: 0,
+    receivedCount: 1,
+    ackCode: "A",
+    parsedAt: "2026-07-02T12:00:00Z",
+    patientControlNumber: `PCN-${id}`,
+  };
+}
+
+function ta1Ack(id: number, controlNumber: string): Ta1Ack {
+  return {
+    id,
+    controlNumber,
+    ackCode: "A",
+    noteCode: "000",
+    interchangeDate: "2026-07-02",
+    interchangeTime: "1200",
+    senderId: "S",
+    receiverId: "R",
+    sourceBatchId: `TA1-${id}`,
+    parsedAt: "2026-07-02T12:00:00Z",
+  };
+}
+
 describe("useMergedTail", () => {
   beforeEach(() => {
     // Singleton store — clear each slice between tests so cases are
@@ -95,6 +123,8 @@ describe("useMergedTail", () => {
     useTailStore.getState().reset("claims");
     useTailStore.getState().reset("remittances");
     useTailStore.getState().reset("activity");
+    useTailStore.getState().reset("acks");
+    useTailStore.getState().reset("ta1_acks");
   });
 
   it("test_merges_base_and_tail_by_id_base_first", () => {
@@ -228,4 +258,50 @@ describe("useMergedTail", () => {
 
     unmount();
   });
+
+  // -------------------------------------------------------------------------
+  // SP25: the Acks page mounts two merge hooks — one per ack flavor.
+  // Both have numeric ids (database row ids) instead of string ids, so
+  // the dedup must compare via String(id) to keep the keyed-by-id
+  // contract intact.
+  // -------------------------------------------------------------------------
+
+  it("test_acks_resource_orders_by_ack_order_and_dedupes", () => {
+    const base = [ack(1, "BASE-A"), ack(2, "BASE-B")];
+    const { addAck } = useTailStore.getState();
+    addAck(ack(2, "REPLAY-B")); // duplicate id — must be dropped
+    addAck(ack(3, "TAIL-C"));
+    addAck(ack(4, "TAIL-D"));
+
+    const { result, unmount } = renderHook(() =>
+      useMergedTail("acks", base),
+    );
+
+    const merged = result.current ?? [];
+    // Base first, then tail in arrival order. Tail's "2" is dropped
+    // because the base already has id 2.
+    expect(merged.map((a) => a.id)).toEqual([1, 2, 3, 4]);
+    // Base version wins for id 2.
+    expect(merged[1]?.sourceBatchId).toBe("BASE-B");
+
+    unmount();
+  });
+
+  it("test_ta1_acks_resource_orders_by_ta1_ack_order_and_dedupes", () => {
+    const base = [ta1Ack(1, "000000001")];
+    const { addTa1Ack } = useTailStore.getState();
+    addTa1Ack(ta1Ack(2, "000000002"));
+    addTa1Ack(ta1Ack(3, "000000003"));
+
+    const { result, unmount } = renderHook(() =>
+      useMergedTail("ta1_acks", base),
+    );
+
+    const merged = result.current ?? [];
+    expect(merged.map((a) => a.id)).toEqual([1, 2, 3]);
+    expect(merged[0]?.controlNumber).toBe("000000001");
+    expect(merged[1]?.controlNumber).toBe("000000002");
+
+    unmount();
+  });
 });