diff --git a/summarize/runner.py b/summarize/runner.py
index e3a3801..fc08627 100644
--- a/summarize/runner.py
+++ b/summarize/runner.py
@@ -437,21 +437,38 @@ def _progress(i: int, n: int, t0: float, c: dict) -> None:
     print(f"  [{i}/{n}] {state}  {elapsed:.0f}s 경과, 약 {eta:.0f}s 남음", file=sys.stderr, flush=True)
 
 
-def _run_calls_parallel(llm, calls: list[dict], concurrency: int) -> None:
-    """calls 각 원소의 'prompt' 를 호출하고 결과를 그 자리에 채운다 (in-place)."""
+def _run_calls_parallel(llm, calls: list[dict], concurrency: int, on_done=None) -> None:
+    """calls 각 원소의 'prompt' 를 호출하고 결과를 그 자리에 채운다 (in-place).
+
+    on_done(call) 은 호출 하나가 끝날 때마다 **메인 스레드에서** 불린다 — 여기서 DB 에 저장하면
+    중간에 끊어도 그때까지 끝난 unit 은 남는다 (고객사 요청 2026-09-21). Ctrl+C 는 남은 호출을
+    취소하고 바로 올라간다 (진행 중인 호출은 응답 상한까지 기다릴 수 있다).
+    """
     if not calls:
         return
     t0 = time.time()
-    if concurrency <= 1 or len(calls) == 1:
+    n = len(calls)
+    if concurrency <= 1 or n == 1:
         for i, c in enumerate(calls, 1):
             c.update(_llm_call(llm, SYSTEM_PROMPT, c["prompt"]))
-            _progress(i, len(calls), t0, c)
+            _progress(i, n, t0, c)
+            if on_done:
+                on_done(c)
         return
-    with ThreadPoolExecutor(max_workers=min(concurrency, len(calls))) as ex:
+    ex = ThreadPoolExecutor(max_workers=min(concurrency, n))
+    try:
         futures = {ex.submit(_llm_call, llm, SYSTEM_PROMPT, c["prompt"]): c for c in calls}
         for i, fut in enumerate(as_completed(futures), 1):
-            futures[fut].update(fut.result())
-            _progress(i, len(futures), t0, futures[fut])
+            c = futures[fut]
+            c.update(fut.result())
+            _progress(i, n, t0, c)
+            if on_done:
+                on_done(c)
+    except KeyboardInterrupt:
+        print("\n중단 요청 — 남은 호출을 취소한다 (이미 끝난 unit 은 저장됨)", file=sys.stderr, flush=True)
+        ex.shutdown(wait=False, cancel_futures=True)
+        raise
+    ex.shutdown(wait=True)
 
 
 def _dedupe_plan(con: sqlite3.Connection, pending: list[sqlite3.Row]) -> tuple[list[sqlite3.Row], dict]:
@@ -581,13 +598,12 @@ def summarize_units(program: str | None, limit: int | None, fake: bool = False,
                 jobs.append((u, [dict(x) for x in prompts]))
 
             # 2) LLM 호출 (병렬, DB 접근 없음) — 수정사항 10번
+            #    + 3) 검증·저장: unit 의 호출이 모두 끝나는 즉시 메인 스레드에서 저장 (중간에 끊어도 보존)
             all_calls = [c for _, calls in jobs for c in calls]
             print(f"[{p['name']}] unit {len(units)}건 → LLM 호출 {len(all_calls)}건 (동시 {conc})",
                   file=sys.stderr, flush=True)
-            _run_calls_parallel(llm, all_calls, conc)
 
-            # 3) 검증·저장 (DB 쓰기, 메인 스레드)
-            for u, calls in jobs:
+            def _save_unit(u: sqlite3.Row, calls: list[dict]) -> None:
                 lines = lines_by_inc.get(u["include"], [])
                 try:
                     r = finish_unit(con, u, calls, lines, text_symbols)
@@ -598,15 +614,26 @@ def summarize_units(program: str | None, limit: int | None, fake: bool = False,
                     con.commit()
                     stats["failed"] += 1
                     print(f"[FAIL] {u['unit_id']}: {err}")
-                    continue
+                    return
                 if r["status"] == "pending":
                     stats["awaiting_response"] += 1
-                    continue
+                    return
                 stats["done"] += 1
                 stats["chunks"] += r["chunks"]
                 stats["dropped"] += r["dropped"]
                 con.commit()
 
+            owner = {id(c): (u, calls) for u, calls in jobs for c in calls}
+            remaining = {u["unit_id"]: len(calls) for u, calls in jobs}
+
+            def _on_call_done(c: dict) -> None:
+                u, calls = owner[id(c)]
+                remaining[u["unit_id"]] -= 1
+                if remaining[u["unit_id"]] == 0:      # 창이 여러 개인 unit 은 마지막 창까지 기다린다
+                    _save_unit(u, calls)
+
+            _run_calls_parallel(llm, all_calls, conc, on_done=_on_call_done)
+
             if run_id is not None:
                 _update_run(con, run_id, stats, llm, t0, status="running")
 
diff --git a/tests/test_summarize_runner.py b/tests/test_summarize_runner.py
index 1fc512e..aa5daf8 100644
--- a/tests/test_summarize_runner.py
+++ b/tests/test_summarize_runner.py
@@ -204,3 +204,26 @@ def test_reload_keeps_chunks_for_unchanged_units(ingested, monkeypatch):
         assert con.execute("SELECT summary_status FROM program WHERE name='ZRUNNER_T1'").fetchone()[0] == "stale"
     finally:
         con.close()
+
+
+
+def test_run_calls_parallel_saves_each_call_on_main_thread_as_it_finishes():
+    """on_done 은 호출이 끝나는 대로, 메인 스레드에서 불린다 (중간 저장의 전제)."""
+    import threading
+    import time as _t
+    from summarize import runner
+
+    class SlowLLM:
+        usage = {}
+        def complete_json(self, system, user):
+            _t.sleep(0.3 if user == "slow" else 0.01)
+            return {"unit_purpose_ko": user, "chunks": []}
+
+    calls = [{"prompt": "slow"}, {"prompt": "a"}, {"prompt": "b"}]
+    seen = []
+    main = threading.get_ident()
+    runner._run_calls_parallel(SlowLLM(), calls, 3, on_done=lambda c: seen.append((c["prompt"], threading.get_ident())))
+    assert [p for p, _ in seen][-1] == "slow"                 # 느린 호출이 끝나기 전에 빠른 것들이 먼저 저장된다
+    assert {p for p, _ in seen} == {"slow", "a", "b"}
+    assert all(tid == main for _, tid in seen)
+    assert all("raw" in c for c in calls)