fix(desktop): show summarizing indicator during auto-compaction

Auto-compression rewrites history mid-turn, which made long threads look
like they reset. Re-tag the gateway lifecycle status as compacting and
surface it in the desktop thread loading indicators.

agent/conversation_compression.py

@@ -40,6 +40,16 @@ from agent.model_metadata import estimate_request_tokens_rough
 
 logger = logging.getLogger(__name__)
 
+# Stable marker the gateway matches on to re-tag the auto-compaction lifecycle
+# status as ``kind="compacting"`` (tui_gateway/server.py::_status_update), so
+# drivers like the desktop app can show an explicit "Summarizing…" indicator
+# instead of the transcript appearing to silently reset. Keep the marker phrase
+# intact if you reword COMPACTION_STATUS.
+COMPACTION_STATUS_MARKER = "Compacting context"
+COMPACTION_STATUS = (
+    f"🗜️ {COMPACTION_STATUS_MARKER} — summarizing earlier conversation so I can continue..."
+)
+
 
 def _compression_lock_holder(agent: Any) -> str:
     """Build a unique holder id for the lock: pid:tid:agent-instance:uuid.
@@ -324,9 +334,7 @@ def compress_context(
         f"{approx_tokens:,}" if approx_tokens else "unknown", agent.model,
         focus_topic,
     )
-    agent._emit_status(
-        "🗜️ Compacting context — summarizing earlier conversation so I can continue..."
-    )
+    agent._emit_status(COMPACTION_STATUS)
 
     # ── Compression lock ────────────────────────────────────────────────
     # Atomic, state.db-backed lock per session_id.  Without this, two
@@ -799,6 +807,8 @@ def try_shrink_image_parts_in_messages(
 
 
 __all__ = [
+    "COMPACTION_STATUS",
+    "COMPACTION_STATUS_MARKER",
     "check_compression_model_feasibility",
     "replay_compression_warning",
     "compress_context",