xint-phased-credential-activation-model

xint unlocks in three discrete phases tied to credential availability: Phase 1 (xAI API key only — 8 commands including analyze, ai-search, report, article, collections), Phase 2 (+ X Bearer Token — 11 commands: search, profile, tweet, thread, trends, watch, stream, media, users, reposts, watchlist), Phase 2b (+ OAuth 2.0 Client ID — 17 command families: engagement, analytics, growth, moderation, bookmark KB). MCP server policy tier must be upgraded from read_only to engagement when Phase 2b credentials are added.