diff --git a/chat/services/scene_summarize.py b/chat/services/scene_summarize.py
index d72ae9b..7551f8b 100644
--- a/chat/services/scene_summarize.py
+++ b/chat/services/scene_summarize.py
@@ -624,12 +624,20 @@ async def apply_scene_close_summary(
                 },
             )
         elif cand.action == "close" and cand.existing_thread_id:
+            # T80.4: chat-clock time, not wall clock — the rest of the
+            # close pipeline (memories, edges, scene_closed payloads)
+            # uses chat["time"] so threads must agree. Falls back to
+            # UTC now only when the chat row has no clock yet (defensive
+            # — chat_state always seeds "time" via chat_created).
+            chat_clock_at = chat.get("time") or datetime.now(
+                timezone.utc
+            ).isoformat()
             append_and_apply(
                 conn,
                 kind="thread_closed",
                 payload={
                     "thread_id": cand.existing_thread_id,
-                    "closed_at": datetime.now(timezone.utc).isoformat(),
+                    "closed_at": chat_clock_at,
                 },
             )
 
diff --git a/tests/test_per_pov_summary.py b/tests/test_per_pov_summary.py
index ae4d35d..a6e7a69 100644
--- a/tests/test_per_pov_summary.py
+++ b/tests/test_per_pov_summary.py
@@ -1673,3 +1673,79 @@ async def test_detect_threads_failure_is_logged(tmp_path, monkeypatch, caplog):
             and "test-detect-threads-boom" in rec.message
             for rec in caplog.records
         ), [r.message for r in caplog.records]
+
+
+@pytest.mark.asyncio
+async def test_thread_closed_uses_chat_clock_time(tmp_path, monkeypatch):
+    """T80.4: emitted ``thread_closed`` events stamp ``closed_at`` with
+    the chat-clock time (chat["time"]), not the host's wall clock. The
+    rest of the close pipeline already does this; threads must agree
+    so timeline reconstruction stays consistent."""
+    from chat.services import thread_detection as td_mod
+
+    canned = json.dumps(
+        {
+            "summary": "BotA had a quick chat.",
+            "knowledge_facts": [],
+            "relationship_summary": "Steady.",
+        }
+    )
+
+    async def fake_detect_threads(client, **kwargs):
+        return td_mod.ThreadDetectionResult(
+            candidates=[
+                td_mod.ThreadCandidate(
+                    action="close",
+                    existing_thread_id="thr_x",
+                    summary="resolved",
+                ),
+            ]
+        )
+
+    monkeypatch.setattr(td_mod, "detect_threads", fake_detect_threads)
+
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    with open_db(db) as conn:
+        _seed_single_bot_scene(conn)
+        # Pre-seed an open thread so the "close" candidate has something
+        # real to close, and pin the chat clock to a known value.
+        from chat.eventlog.log import append_and_apply
+        import chat.state.threads  # noqa: F401
+
+        append_and_apply(
+            conn,
+            kind="thread_opened",
+            payload={
+                "thread_id": "thr_x",
+                "chat_id": "chat_bot_a",
+                "title": "Lingering question",
+                "summary": "What did Maya hide?",
+            },
+        )
+        project(conn)
+        # UPDATE chat_state AFTER project so the re-projection doesn't
+        # overwrite the pinned clock value.
+        chat_clock = "2026-04-26T10:00:00+00:00"
+        conn.execute(
+            "UPDATE chat_state SET time = ? WHERE chat_id = ?",
+            (chat_clock, "chat_bot_a"),
+        )
+
+        client = MockLLMClient(canned=[canned])
+        await apply_scene_close_summary(
+            conn,
+            client,
+            classifier_model="x",
+            chat_id="chat_bot_a",
+            scene_id=1,
+            host_bot_id="bot_a",
+        )
+
+        rows = conn.execute(
+            "SELECT payload_json FROM event_log WHERE kind = 'thread_closed'"
+        ).fetchall()
+        assert len(rows) == 1
+        payload = json.loads(rows[0][0])
+        assert payload["thread_id"] == "thr_x"
+        assert payload["closed_at"] == chat_clock