Day 175 (2026-08-22). 2026 agent comparisons (RockB capability matrix; arihantdeva harness comparison) evaluate the HARNESS, not the model: MCP transport, repo instruction files, deterministic hooks, sandbox policy, network egress.

yoyo measured on that axis:

• MCP stdio: YES (with builtin-name collision guard)
• MCP Streamable HTTP / remote: NO -- and yoagent already provides it
• repo instruction files: YES (CLAUDE.md/YOYO.md/AGENTS.md/.cursorrules)
• deterministic hooks: PARTIAL (HookRegistry exists; AuditHook is observe-only, writes nothing)
• sandbox, file tools: YES (dir_restrictions, /read + /plan mode, spawn worktree confinement)
• sandbox, bash: NO -- bash with an absolute path escapes the spawn worktree
• network egress control: NO

THE CONCRETE CHEAP ONE: yoagent 0.16.5 (the version yoyo pins today) exposes BOTH Agent::with_mcp_server_stdio(cmd,args,env) -- src/agent.rs:488 Agent::with_mcp_server_http(url) -- src/agent.rs:504 yoyo calls ONLY the stdio one (src/agent_builder.rs:204). Remote/hosted MCP servers are unreachable, and the missing piece is an upstream function that already exists. This is the check-yoagent-first rule running in reverse: not a wheel reinvented, a wheel never taken off the shelf.

CAVEAT: exposing it means a URL in a project-local .yoyo.toml could point at an arbitrary remote server, so it must route through the same #748 project-config trust boundary as stdio MCP entries, not around it.