Use it before answering anything about past sessions, earlier decisions or the user's
    preferences, and before brain_remember to avoid writing a duplicate. Not for health
    checks (brain_status) and not for reading a file you already know the path of.

    Read-only. Partial results are normal: `stores` lists hits per store and names any store
    that was unreachable instead of failing the call. A value a `⚠ Fact changed` banner
    superseded is returned but ranked below the banner.

    Use it the moment the user states a fact, decision, correction, preference or
    relationship worth keeping across sessions; one call per item. Not for whole documents
    or web pages (brain_distill) and not for the end-of-session summary (brain_session).

    Never deletes. A near-duplicate fact returns `status: duplicate` with the existing entry
    and writes nothing. A changed value is appended under a `⚠ Fact changed` banner with the
    old line kept, reported as `contradiction`. `layers` reports each store as
    written|exists|pending|failed|refused, so a dead store is visible, never silent. Text
    that looks like a secret is refused.

    start returns the whole context block: the cron daily brief with a stale flag,
    executive state (objective, missions, pending decisions), the configured Hindsight
    mental models, a recall per top mission, the staged-inbox count, and `recovery` when
    the previous session never closed.

    end drains the Hindsight queue, appends a close line to today's session archive,
    replaces executive_state, session_critique and the cross-agent sync file with the
    bodies you pass (or a stub built from this session's brain_remember calls), reports
    which trait signals moved, and writes the clean-close marker. A second end overwrites
    the first.

    Use it for a web page (defuddle with a stdlib fallback), a GitHub repo README, YouTube
    subtitles via yt-dlp, a PDF saved as bytes, a local file, or pasted text. Not for short
    facts (brain_remember).

    Fetches over the network for URLs. The same source or body a second time returns
    `status: exists` and writes nothing. A `note` flags a thin capture (JS-only or paywalled
    page) so you can read it in a browser and call again with `text`.

    Use it when a store seems down, before maintenance, or when the user asks how the
    memory is doing. Not a search (brain_recall). `ok` is false when any store is down or
    lint found issues; `stores` names the failing one.