ticket: split mcp stdio roadmap

.yoi/tickets/00001KVHR3WRY/item.md

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+---
+title: 'MCP: implement stdio JSON-RPC lifecycle client'
+state: 'ready'
+created_at: '2026-06-20T05:30:04Z'
+updated_at: '2026-06-20T05:33:03Z'
+assignee: null
+readiness: 'implementation_ready'
+risk_flags: ['mcp', 'stdio', 'json-rpc', 'process-lifecycle', 'diagnostics']
+---
+
+## Background
+
+After MCP local stdio server config exists, Yoi needs a lifecycle client that can start a configured server, speak newline-delimited JSON-RPC over stdio, perform MCP initialize/capability negotiation, and shut down safely.
+
+This Ticket creates the protocol/lifecycle foundation only. It does not expose MCP tools/resources/prompts to the model-visible ToolRegistry.
+
+## Requirements
+
+- Spawn configured local stdio MCP servers from explicit config only.
+- Use stdin/stdout newline-delimited JSON-RPC.
+- Treat stdout as protocol messages.
+- Treat stderr as bounded diagnostics/logging, not automatic protocol failure.
+- Implement initialize, capability negotiation, and notifications/initialized.
+- Track server name and startup phase in diagnostics.
+- Implement graceful shutdown, terminate, and kill fallback.
+- Handle process exit/disconnect/startup failure with bounded diagnostics.
+- Do not declare sampling or elicitation client capabilities initially.
+- Add local mock MCP server tests.
+
+## Acceptance criteria
+
+- Mock local stdio MCP server initializes successfully.
+- Initialize failure reports server name and phase.
+- stderr is bounded and redacted where needed.
+- Shutdown is safe and deterministic.
+- Sampling/elicitation are not advertised and fail closed if requested.
+- No tools/resources/prompts are registered by this Ticket.
+
+## Non-goals
+
+- tools/list ToolRegistry registration.
+- tools/call execution.
+- resources/prompts operations.
+- Streamable HTTP/OAuth/remote MCP.
+
+## Related work
+
+- Depends on `00001KVHR3WRF`.
+- Objective: `00001KTR80WMN`.