As the Model Context Protocol (MCP) standardizes agent connectivity, the industry is shifting toward persistent, collaborative "Co-Work" agents. However, building production-grade runtimes for these agents requires solving infrastructure challenges that the protocol doesn't define. This session shares battle-tested patterns from a high-density, multi-tenant MCP runtime implementation. We explore four critical pillars: 1) Recursive MCP Bootstrapping: Enabling agents to programmatically manufacture, test, and hot-plug new MCP servers into their own lifecycle at runtime. This shifts from static toolsets to evolving capabilities. 2) Event-Streamed State: Using Redis Streams to maintain agent persistence and handle multi-client synchronization, a requirement for collaborative environments like Claude Co-Work where state must persist across sessions. 3) Git-Backed Sandboxing: Leveraging lightweight filesystem isolation (Git worktrees) to process massive datasets locally via MCP-native primitives without context window bloat. 4) Auth Orchestration: Implementing dynamic OAuth discovery and exchange within the JSON-RPC layer to navigate enterprise boundaries securely.