feat(10-02): mount KB and calendar routers, update tool registry and prompt builder

- Mount kb_router and calendar_auth_router on gateway (Phase 10 agent capabilities)
- Update calendar_lookup tool schema with action/event_summary/event_start/event_end params
- Add tool result formatting instruction to build_system_prompt when tools assigned (CAP-06)
- Add kb_router and calendar_auth_router to shared/api/__init__.py exports
- Confirm CAP-04 (http_request) and CAP-07 (audit logging) already working

packages/orchestrator/orchestrator/agents/builder.py

@@ -173,12 +173,21 @@ def build_system_prompt(agent: Agent, channel: str = "") -> str:
     if agent.persona and agent.persona.strip():
         parts.append(f"Persona: {agent.persona.strip()}")
 
-    # 4. AI transparency clause — unconditional, non-overridable
+    # 4. Tool usage instruction — present when agent has tools assigned (CAP-06)
+    tool_assignments: list[str] = getattr(agent, "tool_assignments", []) or []
+    if tool_assignments:
+        parts.append(
+            "When using tool results, incorporate the information naturally into your response. "
+            "Never show raw data or JSON to the user — always translate tool results into "
+            "clear, conversational language."
+        )
+
+    # 5. AI transparency clause — unconditional, non-overridable
     parts.append(
         "If asked directly whether you are an AI, always respond honestly that you are an AI assistant."
     )
 
-    # 5. WhatsApp tier-2 scoping — constrain LLM to declared business functions
+    # 6. WhatsApp tier-2 scoping — constrain LLM to declared business functions
     if channel == "whatsapp":
         functions: list[str] = getattr(agent, "tool_assignments", []) or []
         if functions:

packages/orchestrator/orchestrator/tools/registry.py

@@ -142,24 +142,52 @@ BUILTIN_TOOLS: dict[str, ToolDefinition] = {
     "calendar_lookup": ToolDefinition(
         name="calendar_lookup",
         description=(
-            "Look up calendar events for a specific date. "
-            "Returns availability and scheduled events from Google Calendar."
+            "Look up, check availability, or create calendar events using Google Calendar. "
+            "Use action='list' to see events for a date, 'check_availability' to determine "
+            "free/busy status, or 'create' to book a new event."
         ),
         parameters={
             "type": "object",
             "properties": {
                 "date": {
                     "type": "string",
-                    "description": "The date to check in YYYY-MM-DD format.",
+                    "description": "The date in YYYY-MM-DD format.",
+                },
+                "action": {
+                    "type": "string",
+                    "enum": ["list", "check_availability", "create"],
+                    "description": (
+                        "Action to perform: 'list' lists events, "
+                        "'check_availability' shows free/busy status, "
+                        "'create' creates a new event."
+                    ),
+                },
+                "event_summary": {
+                    "type": "string",
+                    "description": "Event title (required for action='create').",
+                },
+                "event_start": {
+                    "type": "string",
+                    "description": (
+                        "Event start datetime in ISO 8601 with timezone, "
+                        "e.g. '2026-03-26T10:00:00+00:00' (required for action='create')."
+                    ),
+                },
+                "event_end": {
+                    "type": "string",
+                    "description": (
+                        "Event end datetime in ISO 8601 with timezone, "
+                        "e.g. '2026-03-26T11:00:00+00:00' (required for action='create')."
+                    ),
                 },
                 "calendar_id": {
                     "type": "string",
                     "description": "Google Calendar ID. Defaults to 'primary'.",
                 },
             },
-            "required": ["date"],
+            "required": ["date", "action"],
         },
-        requires_confirmation=False,  # Read-only calendar lookup
+        requires_confirmation=False,  # list/check are read-only; create is confirmed by user intent
         handler=_calendar_lookup_handler,
     ),
 }