diff --git a/chat/services/scene_summarize.py b/chat/services/scene_summarize.py
index 386cf51..49fb375 100644
--- a/chat/services/scene_summarize.py
+++ b/chat/services/scene_summarize.py
@@ -213,7 +213,11 @@ async def _summarize_and_apply_for_witness(
             # Empty default -> skip the memory rewrite; the seeded
             # per-turn pov_summary stays in place.
             continue
-        new_value = pov.summary + key_quotes_suffix
+        # T80.1: a prior close may have already appended a Key quotes
+        # suffix to this row's pov_summary. Strip it here so the fresh
+        # rewrite replaces the existing suffix rather than stacking a
+        # second one on top.
+        new_value = _strip_key_quotes_suffix(pov.summary) + key_quotes_suffix
         append_and_apply(
             conn,
             kind="manual_edit",
@@ -263,6 +267,31 @@ async def _summarize_and_apply_for_witness(
     return pov
 
 
+# T80.1: header marker shared by the suffix builder and the
+# witness-write strip step. Any text starting with this marker is treated
+# as a previously-appended Key quotes suffix and stripped before reuse so
+# repeated scene closes don't compose recursive bloat.
+_KEY_QUOTES_HEADER = "\n\nKey quotes:\n"
+
+
+def _strip_key_quotes_suffix(text: str) -> str:
+    """Remove a previously-appended Key quotes suffix from ``text``.
+
+    Returns ``text`` unchanged when the marker is absent, or the prefix
+    up to (but not including) the marker when present. Used in two
+    places: (1) when sourcing quote text from a memory row that may
+    already carry the suffix from a prior close, and (2) when computing
+    the per-POV rewrite's prior_value so the new write replaces — rather
+    than stacks on — the old suffix.
+    """
+    if not text:
+        return text
+    idx = text.find(_KEY_QUOTES_HEADER)
+    if idx >= 0:
+        return text[:idx]
+    return text
+
+
 def _build_key_quotes_suffix(conn: Connection, scene_id: int) -> str:
     """If the scene's max-turn-significance is >= 2, build the
     "Key quotes:" suffix from the top-3 highest-significance memory rows
@@ -274,6 +303,10 @@ def _build_key_quotes_suffix(conn: Connection, scene_id: int) -> str:
     per-turn narrative seeded by T21, since this helper is called BEFORE
     the per-POV rewrite. Texts are truncated to 200 chars to bound
     memory row growth across many witnesses.
+
+    T80.1: candidate text is run through :func:`_strip_key_quotes_suffix`
+    first so a re-close (whose source memories already carry a suffix from
+    the prior close) doesn't quote a quote.
     """
     row = conn.execute(
         "SELECT MAX(significance) FROM memories WHERE scene_id = ?",
@@ -288,7 +321,7 @@ def _build_key_quotes_suffix(conn: Connection, scene_id: int) -> str:
         (scene_id,),
     )
     quotes = [
-        (r[0] or "")[:200]
+        _strip_key_quotes_suffix(r[0] or "")[:200]
         for r in cur.fetchall()
     ]
     if not quotes:
diff --git a/tests/test_per_pov_summary.py b/tests/test_per_pov_summary.py
index 6984b5c..9be3db1 100644
--- a/tests/test_per_pov_summary.py
+++ b/tests/test_per_pov_summary.py
@@ -1418,3 +1418,75 @@ def test_consumed_digest_does_not_render_again(tmp_path):
         body2 = msgs2[0].content
         assert "Meanwhile while you were away:" not in body2
         assert digest_text not in body2
+
+
+# ---------------------------------------------------------------------------
+# T80: scene_summarize polish bundle.
+# ---------------------------------------------------------------------------
+
+
+@pytest.mark.asyncio
+async def test_scene_close_re_run_does_not_double_suffix(tmp_path):
+    """T80.1: re-running ``apply_scene_close_summary`` on the same scene
+    must NOT stack a second "Key quotes:" suffix on each pov_summary. The
+    builder strips any existing suffix from candidate text before
+    composing the new one, and the per-POV write replaces (not appends
+    to) the existing suffix.
+    """
+    db = tmp_path / "t.db"
+    apply_migrations(db)
+    canned = json.dumps(
+        {
+            "summary": "BotA had a heavy talk with you.",
+            "knowledge_facts": [],
+            "relationship_summary": "Things shifted.",
+        }
+    )
+    no_threads = json.dumps({"candidates": []})
+    with open_db(db) as conn:
+        _seed_single_bot_scene_no_memory(conn)
+        # Significance >= 2 triggers the Key quotes suffix path.
+        _seed_memory(conn, pov_summary="Maya quote one", significance=3)
+        _seed_memory(conn, pov_summary="Maya quote two", significance=2)
+        project(conn)
+
+        # First close.
+        client = MockLLMClient(canned=[canned, no_threads])
+        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 pov_summary FROM memories WHERE scene_id = 1"
+        ).fetchall()
+        assert rows
+        for (pov,) in rows:
+            assert pov.count("Key quotes:") == 1
+
+        # Second close on the same scene with fresh canned responses.
+        client2 = MockLLMClient(canned=[canned, no_threads])
+        await apply_scene_close_summary(
+            conn,
+            client2,
+            classifier_model="x",
+            chat_id="chat_bot_a",
+            scene_id=1,
+            host_bot_id="bot_a",
+        )
+
+        rows2 = conn.execute(
+            "SELECT pov_summary FROM memories WHERE scene_id = 1"
+        ).fetchall()
+        assert rows2
+        for (pov,) in rows2:
+            # Still exactly ONE "Key quotes:" suffix — no recursive bloat.
+            assert pov.count("Key quotes:") == 1
+            # And no nested-quote artifacts (the suffix wasn't sourced
+            # from a row whose text already contained the suffix).
+            inner_count = pov.count("Key quotes:")
+            assert inner_count == 1