perf(multi-agent): add kb_context_projection timing log

surfsense_backend/app/agents/multi_agent_chat/middleware/shared/kb_context_projection.py

@@ -2,6 +2,7 @@
 
 from __future__ import annotations
 
+import time
 from typing import Any
 
 from langchain.agents.middleware import AgentMiddleware, AgentState
@@ -10,6 +11,9 @@ from langgraph.runtime import Runtime
 
 from app.agents.new_chat.filesystem_state import SurfSenseFilesystemState
 from app.agents.new_chat.middleware.knowledge_search import _render_priority_message
+from app.utils.perf import get_perf_logger
+
+_perf_log = get_perf_logger()
 
 
 class KbContextProjectionMiddleware(AgentMiddleware):  # type: ignore[type-arg]
@@ -30,17 +34,34 @@ class KbContextProjectionMiddleware(AgentMiddleware):  # type: ignore[type-arg]
         runtime: Runtime[Any],
     ) -> dict[str, Any] | None:
         del runtime
+        start = time.perf_counter()
         tree_text = state.get("workspace_tree_text")
         priority = state.get("kb_priority")
         if not tree_text and not priority:
+            _perf_log.info(
+                "[kb_context_projection] tree=0 priority=0 elapsed=%.3fs",
+                time.perf_counter() - start,
+            )
             return None
 
         messages = list(state.get("messages") or [])
         insert_at = max(len(messages) - 1, 0)
+        tree_chars = 0
         if tree_text:
+            tree_chars = len(tree_text)
             messages.insert(insert_at, SystemMessage(content=tree_text))
+        priority_count = 0
         if priority:
+            priority_count = (
+                len(priority) if hasattr(priority, "__len__") else 1
+            )
             messages.insert(insert_at, _render_priority_message(priority))
+        _perf_log.info(
+            "[kb_context_projection] tree_chars=%d priority_items=%d elapsed=%.3fs",
+            tree_chars,
+            priority_count,
+            time.perf_counter() - start,
+        )
         return {"messages": messages}