diff --git a/shared/tests/turn.bulkadd.test.js b/shared/tests/turn.bulkadd.test.js
new file mode 100644
index 0000000..9ed4a3d
--- /dev/null
+++ b/shared/tests/turn.bulkadd.test.js
@@ -0,0 +1,49 @@
+// addParticipants (bulk) must slot by initiative, not append.
+const shared = require('@ttrpg/shared');
+const { mockCtx } = require('./_helpers');
+const { buildCharacterParticipant, buildMonsterParticipant, addParticipants, makeParticipant } = shared;
+
+function enc(ps = []) {
+  return { name:'t', participants: ps, isStarted: false, isPaused: false,
+    round: 0, currentTurnParticipantId: null, turnOrderIds: [] };
+}
+function p(id, init) {
+  return makeParticipant({ id, name: id, type: 'monster', initiative: init, maxHp: 10, currentHp: 10 });
+}
+
+describe('addParticipants slot order', () => {
+  test('bulk add slots by initiative desc', async () => {
+    const { ctx } = mockCtx();
+    let e = enc([]);
+    e = await addParticipants(e, [p('a', 5), p('b', 20), p('c', 10)], ctx);
+    expect(e.participants.map(x => x.id)).toEqual(['b', 'c', 'a']);
+  });
+
+  test('bulk add preserves existing order + slots new', async () => {
+    const { ctx } = mockCtx();
+    let e = enc([p('a', 20), p('b', 5)]);
+    e = await addParticipants(e, [p('c', 10)], ctx);
+    expect(e.participants.map(x => x.id)).toEqual(['a', 'c', 'b']);
+  });
+
+  test('bulk add same-init appends after existing (stable tie)', async () => {
+    const { ctx } = mockCtx();
+    let e = enc([p('a', 10)]);
+    e = await addParticipants(e, [p('b', 10), p('c', 10)], ctx);
+    expect(e.participants.map(x => x.id)).toEqual(['a', 'b', 'c']);
+  });
+
+  test('bulk add mixed inits into existing list', async () => {
+    const { ctx } = mockCtx();
+    let e = enc([p('a', 15), p('b', 5)]);
+    e = await addParticipants(e, [p('c', 20), p('d', 10), p('e', 15)], ctx);
+    expect(e.participants.map(x => x.id)).toEqual(['c', 'a', 'e', 'd', 'b']);
+  });
+
+  test('bulk add updates turnOrderIds to match', async () => {
+    const { ctx } = mockCtx();
+    let e = enc([]);
+    e = await addParticipants(e, [p('a', 5), p('b', 20)], ctx);
+    expect(e.turnOrderIds).toEqual(['b', 'a']);
+  });
+});
diff --git a/shared/turn.js b/shared/turn.js
index 0aa485a..ea17394 100644
--- a/shared/turn.js
+++ b/shared/turn.js
@@ -479,14 +479,20 @@ async function addParticipant(encounter, participant, ctx) {
 }
 
 async function addParticipants(encounter, newParticipants, ctx) {
-  const updatedParticipants = [...(encounter.participants || []), ...newParticipants];
+  // Slot each new participant into list by initiative (desc), preserve
+  // existing order + drag-established ties. Matches addParticipant semantics.
+  let base = [...(encounter.participants || [])];
+  for (const np of newParticipants) {
+    const idx = slotIndexForInit(base, np.initiative);
+    base.splice(idx, 0, np);
+  }
   const names = newParticipants.map(p => p.name).join(', ');
-  const patch = { participants: updatedParticipants };
+  const patch = { participants: base, ...syncTurnOrder(base) };
   const log = {
     type: 'add_participants',
     message: `Added ${newParticipants.length} participant${newParticipants.length === 1 ? '' : 's'}: ${names}`,
     delta: { count: newParticipants.length },
-    undo: { participants: newParticipants },
+    undo: { participants: newParticipants, newTurnOrderIds: patch.turnOrderIds },
   };
   return commit(encounter, patch, log, ctx);
 }