feat(hub): the mail state is a panel section, and a ceiling falling is an event

The figure was a line beside the settings form, which is where it is changed
and not where it is watched. It sits with the other live figures under
Statistics now — four cards and, above them, a banner saying which of the two
ceilings has fallen. The two states are not the same to whoever is reading:
one means newcomers are turned away, the other means somebody locked out of
their account cannot get back in. The settings block keeps a line pointing at
it.

And an operator no longer has to be looking. When a global ceiling is reached
the administrators are notified — in `mail.py`, in its own session, never
raising, because this runs while a request is being refused and an alert that
fails must not turn a refusal into a 500. Once per hour, keyed on a row
rather than a flag in memory: a flood is what spends the budget, so one alert
per refusal would bury the message under its own cause, and a hub that is
refusing mail is a hub somebody is about to restart.

`/v1/admin/mail` gains `general_exhausted` and `all_exhausted` rather than
leaving the panel to compare two numbers.

Labels in all ten catalogues; `.warn-msg` for the middle state, on the
`--warn` token both themes already define.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T4YmK41VsEURWFdop4EEeT

1 files changed, 2 insertions, 1 deletions

diff --git a/docs/MESHBAY_DESIGN.md b/docs/MESHBAY_DESIGN.md
index be74e64..577612d 100644
--- a/docs/MESHBAY_DESIGN.md
+++ b/docs/MESHBAY_DESIGN.md
@@ -2531,7 +2531,8 @@ had already been asked.
 | **AV11** | **A namespace a client writes into is closed, and its rows are capped.** The preference key space is an allow-list plus `default_tab:<group_id>` checked as a group id, the value is length-bounded, and the row count per account is bounded |
 | **AV12** | **Every list has an upper bound on `limit` and a floor under `offset`.** Including the ones that take no authentication at all — the public group directory and the content blocklist |
 | **AV16** | **A bound the operator can see and change, and that a restart does not forget.** The mail allowance lives in `mail_quota`, not in a module dict — a deploy used to hand out a fresh budget, and the hub is deployed often. The values are settings with defaults in `hub.toml` and a block in the admin panel, because the hour a budget runs out is not when anyone wants to edit a file and restart; `/v1/admin/mail` says how much of the hour is left, which was previously visible only as an absence of mail |
-| **AV17** | **The hub runs on exactly one worker, and says so at startup.** `_connected_nodes`, `_node_groups`, `_webrtc_answers` and the relay registry are per-process: a second worker makes a node intermittently unreachable for half its members, which is a symptom that describes something else entirely |
+| **AV17** | **A global ceiling being reached is an event, not an absence.** When the hourly budget runs out the administrators are notified — once per hour, because a flood is what spends it and one alert per refusal buries the message under its own cause — and the panel says which of the two ceilings fell: newcomers turned away, or somebody locked out of their account unable to get back in |
+| **AV18** | **The hub runs on exactly one worker, and says so at startup.** `_connected_nodes`, `_node_groups`, `_webrtc_answers` and the relay registry are per-process: a second worker makes a node intermittently unreachable for half its members, which is a symptom that describes something else entirely |
 | **AV14** | **MHP binds its audience, and the hub reads its own identity at call time.** A token is minted for one peer and accepted by that peer only. `federation.py` bound `_hub_id` and `_hub_sk_pem` at import, which is before `load_hub_keypair` runs, so it signed with `None` and called itself `meshbay.org` whatever the instance was named — and the verifier named no audience for the `aud` the issuer sets, which PyJWT refuses outright. MHP could not complete one authenticated request between two hubs |
 | **AV15** | **A hash is checked for shape before it is a key lookup**, on the unauthenticated blocklist endpoints a node consults |