Kaisho v2.9.2

A review pass over the whole codebase. Everything below was
reproduced before it was fixed, and each has a test that
fails against the old code.

Security:

• Keep checking the URL allowlist after a redirect [#256].
  It was checked once, against the URL handed in, and
  urlopen follows redirects: an allowed host answering 302
  could hand the model anything this machine can reach, and
  the result is written into the inbox. Both fetch paths,
  including the tool where the model picks the URL.
• Check the KB subdir by path, not by string prefix [#257].
  startswith let a sibling directory whose name begins
  with the KB's name through, so ../kb-private resolved
  outside the KB and passed. _safe_path, in the same file,
  already documents that bypass.

Things that could not stop, or stopped wrong:

• Bound the pull loop [#255]. Five while True loops that
  end only if the server advances its cursor. Against one
  that does not: 11990 requests in five seconds, from a sync
  that runs by itself every five minutes.
• Back off when the cloud rejects the key [#260]. The
  WebSocket reset its backoff whenever the connect returned,
  and a refused session returns the same way a good one
  does. A revoked sync token meant a reconnect every two
  seconds, indefinitely.
• Make a weekly task weekly [#259]. The recurrence check
  turned on set_task_property, which no backend has, so
  every pass looked like the first: a weekly template
  produced seven tasks a week, a quarterly one ninety.

Answers that were not answers:

• Say something when the advisor runs out of turns [#262].
  The Claude path returned "", which the UI renders as a
  blank reply; the others returned the last tool result as
  prose.
• Say why a cron job produced nothing [#263]. The same, into
  the inbox, unattended.
• Catch cron context errors per section, as documented
  [#261]. The docstring promised it and there was no try
  at all, so one failing backend call cost the whole block
  and the briefing was written blind, reading exactly like a
  briefing about an empty week.

Desktop shell:

• Stop the launcher killing the app that is running [#265].
  lsof -ti :8765 lists every socket on that port on either
  end, including the webview of a running Kaisho. The
  Windows branch already guarded against this and names the
  case in its comment; the fix never reached lsof.
• Give the backend calls a deadline [#266]. A sidecar that
  accepts and never answers froze the tray ticker on a Tokio
  worker until restart.

Frontend:

• Read org timestamps with a non-English weekday [#267].
  Kaisho writes English abbreviations on purpose, but these
  files are edited in Emacs, and a German one writes Mo,
  Di, Mi. Those fell through to the date-only branch and
  rendered a 09:00 entry at midnight.
• Format the clock widget heading in the selected language
  [#267]. It was hardcoded to en-US, next to a heading
  that says "Heute" the rest of the time.
• Translate the four keys that rendered as their own name
  [#264], including the Settings language heading, whose
  || "Language" fallback could never fire.
• Stop writing one profile's state into another [#268].
  Until the active profile was known, writes landed under
  default:, and a read could move a legacy value into the
  wrong profile and delete the original.

Also: stop offering hosting we do not do [#258], and the
first tests for the frontend and the Tauri crate, neither of
which had any.

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Full changelog: https://github.com/ridingbytes/kaisho/blob/master/CHANGELOG.md