feat(claude_code): APIRequest.mcp_config + disable CLI built-ins (2.0.5)

[CocoRoF]

Summary

Phase-I foundation for MCP-wrapped tools on claude_code_cli sessions. Surfaces the host's tool registry to the CLI's LLM without breaking the Stage 6 → Stage 10 → Stage 16 pipeline interface.

The problem

Stage 6 with provider claude_code_cli was the lone outlier in the otherwise provider-symmetric surface: every SDK client (anthropic / openai / google / vllm) accepts APIRequest.tools and passes schemas natively to the LLM. The CLI client dropped them — the LLM saw only the CLI's built-in palette (Bash / Read / Write / Glob / ToolSearch / …) and hallucinated against it whenever the host's intent referenced a Geny custom tool. Symptom on prod: "Tool execution complete: 32 calls, 29 errors".

What this PR ships (executor side)

• APIRequest.mcp_config: Optional[Dict[str, Any]] — per-request MCP server configuration. CLI-based backends serialize to --mcp-config <json>; SDK-based backends ignore it.
• claude_code_argv reads request.mcp_config (precedence over the per-client kwarg). When ANY MCP config is supplied, also emits:
  • --tools "" — disable CLI's built-in tool palette so the LLM cannot hallucinate against tools the host has no executor for. Skipped when caller explicitly passed allow_tools (mixed surface support).
  • --strict-mcp-config — ignore user-level / project-level MCP config sources so the per-session bridge is the sole surface.
• Legacy callers without any MCP config keep today's behaviour exactly.

A companion Geny PR will ship the actual MCP bridge (stdio script) + HTTP endpoint that consume this wire.

Stage interface preservation

The Stage 6 → Stage 10 → Stage 16 interface is preserved. When the CLI uses MCP to call a host tool, the call is dispatched inside the CLI's agentic loop (via the bridge → host HTTP endpoint) and the final APIResponse carries only the assistant message — no tool_use blocks for Stage 10 to dispatch. Stage 10 sees no tool_use → naturally no-ops. Stage 16 sees no pending state → naturally finishes. Memory / persona / persistence stages run identically because the canonical APIResponse shape is the same.

Anthropic API path keeps the per-iteration tool-dispatch loop; the CLI path collapses it inside one CLI invocation. Both produce identical canonical outputs.

Test plan

• 4 new argv tests (request_mcp_config_overrides_kwarg / host_mcp_disables_cli_builtins_and_strict / host_mcp_with_explicit_allow_tools_keeps_builtins / no_mcp_no_tools_flag)
• Full tests/llm_client/ 193/193 pass
• Manual smoke once Geny consumer PR lands

Release

2.0.5. Migration: none — purely additive. Legacy callers' argv is byte-identical.