Complete MCP SLVP Surface

The current MCP closeout proves the ChatGPT Slack evidence path: search can show bounded evidence, readrecordfield can return an inline field window, and projected fetch avoids file materialization for ordinary messages.

SLVP here means Stripe, Linear, Vercel, and Plaid-level product and protocol quality: the surface is obvious, hard to misuse, honest under failure, and verified as a journey rather than as isolated payload fields.

The MCP adapter SHALL expose an evidence ladder in model-visible output: compact discovery, bounded visible evidence, explicit bounded field/window read, and full fetch or export only when needed.