Use when the user refers to THEIR portfolio(s) or holdings — e.g. "my portfolios", "what portfolios do I have", "how are my investments doing", "show my holdings", "my account". Lists the signed-in Bullrun user's virtual portfolios with computed summaries: name, base currency, total value (USD), day change, cost basis and total return, plus position counts. Start here when a portfolio question doesn't name a specific portfolio, then pass a portfolioId to get_portfolio_context or get_portfolio_analytics. Requires connecting this server to a Bullrun account (OAuth, read:portfolios scope) — it returns that user's own data only. privacyMode defaults to "full" (includes absolute $ amounts); pass "weights_only" to hide absolute money and return only relative figures (returns %, counts). Read-only.