feat: port MCP retrieval and write hardening

- align os MCP/runtime/docs with ra-h contract
- add safe direct node lookup and context-optional flows
- gate edge and context writes behind confirmation

app/api/nodes/direct-search/route.ts

@@ -0,0 +1,43 @@
+import { NextRequest, NextResponse } from 'next/server';
+import { directNodeLookup } from '@/services/retrieval/directNodeLookup';
+
+export const runtime = 'nodejs';
+
+export async function POST(request: NextRequest) {
+  try {
+    const body = await request.json();
+    const query = typeof body.query === 'string' ? body.query : '';
+
+    if (!query.trim()) {
+      return NextResponse.json({
+        success: false,
+        error: 'Missing required field: query',
+      }, { status: 400 });
+    }
+
+    const result = await directNodeLookup({
+      search: query,
+      limit: typeof body.limit === 'number' ? body.limit : undefined,
+      context_name: typeof body.context_name === 'string' ? body.context_name : undefined,
+      contextId: typeof body.contextId === 'number' ? body.contextId : undefined,
+      createdAfter: typeof body.createdAfter === 'string' ? body.createdAfter : undefined,
+      createdBefore: typeof body.createdBefore === 'string' ? body.createdBefore : undefined,
+      eventAfter: typeof body.eventAfter === 'string' ? body.eventAfter : undefined,
+      eventBefore: typeof body.eventBefore === 'string' ? body.eventBefore : undefined,
+    });
+
+    return NextResponse.json({
+      success: true,
+      data: {
+        count: result.count,
+        nodes: result.nodes,
+        filters_applied: result.filtersApplied,
+      },
+    });
+  } catch (error) {
+    return NextResponse.json({
+      success: false,
+      error: error instanceof Error ? error.message : 'Failed to run direct node lookup',
+    }, { status: 500 });
+  }
+}