From a7c44e9ededd7c445897be4afa48de209bd5c7cd Mon Sep 17 00:00:00 2001
From: kshitijk4poor <82637225+kshitijk4poor@users.noreply.github.com>
Date: Thu, 24 Sep 2026 19:50:47 +0530
Subject: [PATCH] docs(gateway): say the sub-floor segment-break preamble is
 dropped, not accumulated
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The #99026 guard returns True at a tool-boundary finalize, so _end_segment
treats the segment as delivered and resets it: a 1-3 char preamble ("Ok")
is discarded on non-cumulative transports. Carrying it into the next
segment is not done here: the authoritative finish(final_text) adoption
replaces the carried buffer wholesale, and coalesced 'Ok'×N crosses the
floor and lands as its own message anyway. Record the tradeoff.
---
 gateway/stream_consumer_transport.py | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gateway/stream_consumer_transport.py b/gateway/stream_consumer_transport.py
index c111d322f5..773099436b 100644
--- a/gateway/stream_consumer_transport.py
+++ b/gateway/stream_consumer_transport.py
@@ -334,10 +334,13 @@ class StreamTransportMixin:
         # A segment-break finalize never carries the cursor, so gate it too or a 1-2 token
         # preamble lands durably at every tool boundary and resets the progress anchor
         # (#99026).  Turn finals are exempt: a short complete answer must be delivered.
+        # Tradeoff: on non-cumulative transports the held preamble is DROPPED, not
+        # carried — _end_segment sees update_visible=True and resets the segment.
         preamble_finalize = finalize and not is_turn_final
         if (self._message_id is None and len(visible_stripped) < self._MIN_NEW_MSG_CHARS
                 and (preamble_finalize or (self.cfg.cursor and self.cfg.cursor in text))):
-            return True  # too short for a standalone message — accumulate more
+            # Mid-stream: accumulate more.  Segment-break finalize: dropped (see above).
+            return True
 
         # A failed native/draft transport disables itself and falls through so the
         # accumulated text still reaches the user via edit/send.