profiles: restricted profiles for ordinary users, and a role gate that holds ...

`is_admin_only` was checked in one place out of nine and was not read from
config.json at all, so all seven profiles were reachable by every account with
role `user`. The flag now lives in config.json — the file is the baseline, a
`profile_overrides` row still wins on top of it — and one predicate,
`admin_only_blocked`, is the single place the rule is expressed. The nine
surfaces that list, switch to, spawn or resolve a profile all consult it:
`POST /sessions`, the WebSocket, switch_profile, list_profiles, the system
prompt's "Available profiles" block, spawn_agent and the Synapse reaction
runner. The prompt cache is now keyed by (profile, role), so a user's prompt
can never be served an admin's profile list.

The seven existing profiles (developer, discuss, dispatcher, modeler_3d,
navi_code, secretary, server_admin) are marked admin-only. Three new ones take
their place for ordinary users: assistant, designer_3d and coder. They share one
native tool set — ssh_exec, peer, reload_tools, create_mcp_server, test_mcp_tool,
image_view and gmail are withheld — and differ only in system prompt, model and
MCP groups. navi-web's raw `request` group, and the whole of gnexus-creds and
tgclient, are withheld too.

MCP per-user keys gain the missing half of the rule: a server that declares a
`user_key` slot is refused to anyone but an admin who has no personal key, and
is left out of their tool list entirely, instead of quietly falling back to the
owner's credential and appearing as a tool that cannot work. The refusal names
the server and points at Settings.

Also closes `GET /agents/prompts`, which served every profile's system prompt to
anyone, with no user dependency at all.

The accepted residual risk is written down in docs/profiles.md: the working
directory is a convention, not a sandbox.

startup, llm, profiles, todo: five more the prod logs gave up ...

The same 5-day sweep of prod's journal as 5e51f87, continued. Every one of
these failed silently: no error in the UI, just a line in the log or a hole
in the database.

complete()/embed() retry a connection error before falling back.
stream_complete has always given its first chunk two attempts, but the
non-streaming path made exactly one per (server, model), and with a single
configured server (ollama.com) one ReadTimeout raised "All backends
exhausted: ReadTimeout" outright. That is the whole story of 2026-10-08,
when 27 calls died that way in a day — 23 of them memory summarisation, the
rest planning. Attempts now come from settings.llm_complete_retries (2) with
llm_retry_backoff_sec (2.0) between them; a missing model is still not
retried (a 404 is an answer, not a hiccup), and a lone server is still never
blacklisted — blacklisting it would block the next request for _TTL.

Startup waits for Postgres. create_container() opens the pool eagerly and
the retry loop for the DDL tables sits below it, so a host that comes up
before docker takes the whole lifespan with it. On 2026-10-07 15:19:40 the
agent ran `sudo reboot` on itself at the user's request ("Перезагрузи
себя"); the host booted 15:20:03, navi started at 15:20:18, hit
ConnectionRefusedError on the pool and logged "Application startup failed.
Exiting." Connection errors now retry for ~30s; a genuinely broken config
(a missing DATABASE_URL) still fails fast.

The profile loader reports its tally. A profile dropped by an unreadable
config.json is skipped by design so it cannot take the server down, but on
that same 15:20 boot four of them — modeler_3d, navi_code, secretary,
server_admin — were dropped with `Extra data: line 125 column 1`, and the
only trace was one error line each: the UI simply showed four profiles
fewer.

todo recovers a dropped `op`. Of the 3385 todo calls stored on prod, 73
arrived with the discriminator flattened away ({"index": 1, "status":
"in_progress"}, {"action": "view"}, {"": "add", "tasks": [...]}) and got a
bare "Unknown op: None" — a wasted round trip for an intent the remaining
arguments state plainly. The error message now names the five ops and what
each needs.

Message.created_at is stamped at creation. It defaulted to None and only
some construction sites filled it, so 85% of stored rows had no timestamp at
all (every tool message, 14 168 of 14 168) and no query could slice history
by time or measure a pause. Loading a row passes the column through
explicitly, so NULL rows stay NULL instead of being restamped with "now".

Every new test was checked to fail with its fix reverted. Full suite green
(1466 passed, 1 skipped). No frontend or dependency change, so the deploy is
a pull and a restart.