I agree with the core of what you're saying, but I think the real split isn't "Anthropic trustworthy or not" — it's: what's proprietary vs what's open in the stuff you're actually building on. Routines, Projects, Artifacts, Skills — that's vendor-specific, disposable by definition. MCP, CLAUDE.md, markdown in your repo — that's portable. If Anthropic pivots or nerfs the thing tomorrow, you just rewire your MCP tools onto another harness in 10 minutes. Personally I build my agent workflows as scripts + MCP tools — called by Claude Code today, callable by whatever harness replaces it tomorrow. The building block is "a set of MCP tools + one CLAUDE.md", not "a Routine defined in Anthropic's console". Functionally the same, zero lock-in. Routines are fine for quick-wins, but the moment you start stacking them into a real workflow you're just moving your tech debt into a proprietary format. At that point you might as well externalize to scripts from the start.