perf(prompt): cache kanban worker guidance at session init (#24402)

agent/agent_init.py

@@ -828,15 +828,25 @@ def init_agent(
         tool_names = sorted(agent.valid_tool_names)
         if not agent.quiet_mode:
             print(f"🛠️  Loaded {len(agent.tools)} tools: {', '.join(tool_names)}")
-
             # Show filtering info if applied
             if enabled_toolsets:
                 print(f"   ✅ Enabled toolsets: {', '.join(enabled_toolsets)}")
             if disabled_toolsets:
                 print(f"   ❌ Disabled toolsets: {', '.join(disabled_toolsets)}")
     elif not agent.quiet_mode:
         print("🛠️  No tools loaded (all tools filtered out or unavailable)")
-
+
+    # Kanban worker/orchestrator lifecycle guidance is session-static:
+    # the dispatcher decides at spawn time whether this process is a kanban
+    # worker (kanban_show tool is present iff HERMES_KANBAN_TASK is set).
+    # Resolving the ~835-token block once here avoids re-running the
+    # membership test + reference on every system-prompt rebuild
+    # (init + each context compression).
+    from agent.prompt_builder import KANBAN_GUIDANCE
+    agent._kanban_worker_guidance = (
+        KANBAN_GUIDANCE if "kanban_show" in agent.valid_tool_names else ""
+    )
+
     # Check tool requirements
     if agent.tools and not agent.quiet_mode:
         requirements = _ra().check_toolset_requirements()

agent/system_prompt.py

@@ -111,8 +111,12 @@ def build_system_prompt_parts(agent: Any, system_message: Optional[str] = None)
     # Kanban worker/orchestrator lifecycle — only present when the
     # dispatcher spawned this process (kanban_show check_fn gates on
     # HERMES_KANBAN_TASK env var). Normal chat sessions never see
-    # this block.
-    if "kanban_show" in agent.valid_tool_names:
+    # this block. Resolved once at __init__ (see _kanban_worker_guidance).
+    _kanban_guidance = getattr(agent, "_kanban_worker_guidance", None)
+    if _kanban_guidance:
+        tool_guidance.append(_kanban_guidance)
+    elif _kanban_guidance is None and "kanban_show" in agent.valid_tool_names:
+        # Fallback for code paths that bypass agent_init (rare).
         tool_guidance.append(KANBAN_GUIDANCE)
     if tool_guidance:
         stable_parts.append(" ".join(tool_guidance))