M13: harden MCP trust boundary

backend/app/api/routers/mcp_integrations.py

@@ -3,11 +3,11 @@ from __future__ import annotations
 import uuid
 from datetime import date
 
-from fastapi import APIRouter, Depends, Header, Query
+from fastapi import APIRouter, Depends, Header, Query, Response
 from sqlalchemy import select
 from sqlalchemy.orm import Session
 
-from app.api.deps import get_db, require_mcp_service_token
+from app.api.deps import McpClientContext, get_db, require_mcp_service_token
 from app.core.config import get_settings
 from app.core.errors import AppError
 from app.models.booking import Booking
@@ -42,7 +42,8 @@ def get_correlation_id(
 
 
 def _audit_service_request(
-    db: Session, *, client_id: str, tool: str, status_label: str, correlation_id: str
+    db: Session, *, client_id: str, tool: str, status_label: str, correlation_id: str,
+    metadata: dict[str, object] | None = None,
 ) -> None:
     record_audit_event(
         db,
@@ -51,43 +52,53 @@ def _audit_service_request(
         action="mcp_tool_request",
         entity_type="mcp_tool",
         correlation_id=uuid.UUID(correlation_id),
-        metadata={"tool": tool, "status": status_label},
+        metadata={"tool": tool, "status": status_label, **(metadata or {})},
     )
     db.commit()
 
 
+def _set_trace_headers(response: Response, correlation_id: str, tenant: str) -> None:
+    response.headers["X-Correlation-Id"] = correlation_id
+    response.headers["X-Tenant-Id"] = tenant
+    response.headers["Cache-Control"] = "no-store"
+
+
 @router.get("/operations-summary", response_model=OperationsSummaryOut)
 def operations_summary(
+    response: Response,
     db: Session = Depends(get_db),
-    client_id: str = Depends(require_mcp_service_token),
+    client: McpClientContext = Depends(require_mcp_service_token),
     correlation_id: str = Depends(get_correlation_id),
 ) -> OperationsSummaryOut:
     metrics = compute_metrics(db)
+    _set_trace_headers(response, correlation_id, client.tenant)
     _audit_service_request(
         db,
-        client_id=client_id,
+        client_id=client.client_id,
         tool="fleet_ops_get_operations_summary",
         status_label="ok",
         correlation_id=correlation_id,
     )
-    return OperationsSummaryOut(tenant=settings.ragcore_tenant, metrics=metrics)
+    return OperationsSummaryOut(tenant=client.tenant, metrics=metrics)
 
 
 @router.get("/attention-vehicles", response_model=list[AttentionVehicleOut])
 def attention_vehicles(
+    response: Response,
     minimum_severity: str = Query(default="medium", pattern="^(low|medium|high)$"),
     date_filter: date | None = Query(default=None, alias="date"),
     limit: int = Query(default=20, ge=1, le=50),
     db: Session = Depends(get_db),
-    client_id: str = Depends(require_mcp_service_token),
+    client: McpClientContext = Depends(require_mcp_service_token),
     correlation_id: str = Depends(get_correlation_id),
 ) -> list[AttentionVehicleOut]:
     results = list_attention_vehicles(
         db, minimum_severity=minimum_severity, on_or_before=date_filter, limit=limit
     )
+    _set_trace_headers(response, correlation_id, client.tenant)
     _audit_service_request(
         db,
-        client_id=client_id,
+        client_id=client.client_id,
         tool="fleet_ops_list_attention_vehicles",
         status_label="ok",
         correlation_id=correlation_id,
@@ -98,15 +109,17 @@ def attention_vehicles(
 @router.get("/vehicles/{vehicle_ref}", response_model=McpVehicleDetailOut)
 def vehicle_details(
     vehicle_ref: str,
+    response: Response,
     db: Session = Depends(get_db),
-    client_id: str = Depends(require_mcp_service_token),
+    client: McpClientContext = Depends(require_mcp_service_token),
     correlation_id: str = Depends(get_correlation_id),
 ) -> McpVehicleDetailOut:
+    _set_trace_headers(response, correlation_id, client.tenant)
     vehicle = db.scalar(select(Vehicle).where(Vehicle.public_ref == vehicle_ref))
     if vehicle is None:
         _audit_service_request(
             db,
-            client_id=client_id,
+            client_id=client.client_id,
             tool="fleet_ops_get_vehicle_details",
             status_label="not_found",
             correlation_id=correlation_id,
@@ -128,7 +141,7 @@ def vehicle_details(
 
     _audit_service_request(
         db,
-        client_id=client_id,
+        client_id=client.client_id,
         tool="fleet_ops_get_vehicle_details",
         status_label="ok",
         correlation_id=correlation_id,
@@ -150,18 +163,29 @@ def vehicle_details(
 @router.post("/search-knowledge", response_model=GroundedAnswer)
 def search_knowledge(
     body: McpKnowledgeSearchRequest,
+    response: Response,
     db: Session = Depends(get_db),
-    client_id: str = Depends(require_mcp_service_token),
+    client: McpClientContext = Depends(require_mcp_service_token),
     correlation_id: str = Depends(get_correlation_id),
 ) -> GroundedAnswer:
     provider = get_knowledge_provider()
     answer = provider.ask(body.question, correlation_id, language=body.locale)
+    source_count_available = len(answer.sources)
     answer.sources = answer.sources[: body.max_sources]
+    _set_trace_headers(response, correlation_id, client.tenant)
+    response.headers["X-Sources-Available"] = str(source_count_available)
+    response.headers["X-Sources-Returned"] = str(len(answer.sources))
     _audit_service_request(
         db,
-        client_id=client_id,
+        client_id=client.client_id,
         tool="fleet_ops_search_knowledge",
         status_label=answer.evidence_state,
         correlation_id=correlation_id,
+        metadata={
+            "tenant": client.tenant,
+            "locale": body.locale,
+            "sources_available": source_count_available,
+            "sources_returned": len(answer.sources),
+        },
     )
     return answer