From df35836b75d46d819984fd051ff9113983183191 Mon Sep 17 00:00:00 2001
From: Rocky <rocky@veloxwarp.com>
Date: Thu, 24 Sep 2026 18:01:04 +0300
Subject: [PATCH] fix: preserve transcript generations in sidebar projection

Rocky-Actor: Hermes Rocky
Rocky-Mode: interactive
---
 api/route_session_list_cache.py               |  2 +
 .../webui-run-state-consistency-contract.md   |  4 +-
 tests/test_sidebar_generation_projection.py   | 48 +++++++++++++++++++
 3 files changed, 53 insertions(+), 1 deletion(-)
 create mode 100644 tests/test_sidebar_generation_projection.py

diff --git a/api/route_session_list_cache.py b/api/route_session_list_cache.py
index b91ba7b8..41ea7d22 100644
--- a/api/route_session_list_cache.py
+++ b/api/route_session_list_cache.py
@@ -53,6 +53,8 @@ _SIDEBAR_SESSION_RESPONSE_FIELDS = {
     "model",
     "model_provider",
     "message_count",
+    "transcript_generation",
+    "transcript_generation_baseline",
     "user_message_count",
     "created_at",
     "updated_at",
diff --git a/docs/rfcs/webui-run-state-consistency-contract.md b/docs/rfcs/webui-run-state-consistency-contract.md
index 408fd3e0..78cc89bf 100644
--- a/docs/rfcs/webui-run-state-consistency-contract.md
+++ b/docs/rfcs/webui-run-state-consistency-contract.md
@@ -171,7 +171,9 @@ writes.
 - **Viewed counts are generation-scoped.** Session mutation routes increment the
   persisted `transcript_generation` whenever edit, regenerate, retry, undo, clear,
   or truncate reduces the visible transcript, and record the retained count as
-  `transcript_generation_baseline`. A newer generation replaces an older one even
+  `transcript_generation_baseline`. Both fields survive the bounded `/api/sessions`
+  projection for visible and sidebar-reference rows, including cached responses.
+  A newer generation replaces an older one even
   when its count is lower; counts are monotonic only within one generation and
   merge by maximum there. A client first observing a newer generation acknowledges
   only that retained baseline, so messages added after the shrink remain unread
diff --git a/tests/test_sidebar_generation_projection.py b/tests/test_sidebar_generation_projection.py
new file mode 100644
index 00000000..2454481c
--- /dev/null
+++ b/tests/test_sidebar_generation_projection.py
@@ -0,0 +1,48 @@
+"""The sessions route must carry shrink metadata through to unread decisions."""
+import json
+import shutil
+
+import pytest
+
+from tests.test_issue4766_sidebar_source_pushdown import (
+    _handle_sessions,
+    _install_common_monkeypatches,
+)
+from tests.test_issue856_background_completion_unread import _run_unread_behavior
+
+
+@pytest.mark.skipif(shutil.which("node") is None, reason="node not on PATH")
+@pytest.mark.parametrize("retained", [0, 2])
+def test_sessions_route_preserves_post_shrink_unread(monkeypatch, retained):
+    import api.routes as routes
+    from api.models import Session
+    from api.session_ops import truncate_session_at_keep
+
+    session = Session(session_id="X", messages=[
+        {"role": "user", "content": str(i)} for i in range(10)
+    ])
+    truncate_session_at_keep(session, retained)
+    session.messages.append({"role": "assistant", "content": "new response"})
+    row = session.compact()
+    _install_common_monkeypatches(monkeypatch, [row])
+    routes._session_list_cache_clear()
+    try:
+        # Exercise both the initial projection and the cached response.
+        for _ in range(2):
+            response = _handle_sessions("http://example.com/api/sessions?sidebar_source=webui")
+            assert response.status == 200
+            [projected] = response.json_body()["sessions"]
+            result = _run_unread_behavior("""
+store[SESSION_VIEWED_COUNTS_KEY] = JSON.stringify({
+  X: {message_count: 10, transcript_generation: 0},
+});
+const unread = _hasUnreadForSession(""" + json.dumps(projected) + """);
+console.log(JSON.stringify({unread, viewed: JSON.parse(store[SESSION_VIEWED_COUNTS_KEY]).X}));
+""")
+            assert result == {
+                "unread": True,
+                "viewed": {"message_count": retained, "transcript_generation": 1},
+            }
+            assert "messages" not in projected
+    finally:
+        routes._session_list_cache_clear()