memory+llm: three failures the prod logs gave up ...

All three came out of a survey of the last days of journalctl on prod,
and each one silently destroyed something the user had already paid for.

memory_facts: the no-embedding INSERT bound $13 while its column list
had 12 entries, so every fact written while the embedding backend was
down died on PostgresSyntaxError and the extraction was lost — 47
embed failures in three days, most of them landing in this branch.

Embedding input now gets clipped instead of 400'd away. A 400 takes the
whole embedding with it and recall drops to ILIKE over everything; a
reaction-session prompt (a full event envelope inlined) did that 41
times. settings.embedding_max_chars (6000, 0 disables) caps the input
at the model's window, so recall still works on the head of the text.

Message strips NUL bytes at the model boundary. PostgreSQL text cannot
hold one, and a NUL arriving in a tool result (reading a binary file)
made the whole session_messages INSERT fail with
CharacterNotInRepertoireError — the turn died and the user lost it.
Three times on 2026-10-07. As a Message validator it covers every
writer downstream: session store, kv store, memory extraction.

Each new test was checked to fail with its fix reverted.

tui: show the currently-served model in the status panel ...

The status panel's Model line was fed the global ollama_default_model, not the
session/profile model, and the server never told the client which model
actually served a call. Now:

- Backends stamp the resolved model onto LLMChunk (first chunk) / LLMResponse.
  The fallback backend reports the model that survived its server+model
  priority list (may differ from the profile's first choice).
- New ModelInfo event ({"type":"model_info","model":...}) emitted once per
  turn from agent._consume_stream, re-emitted only when the model changes
  across iterations. Additive WS event — old clients ignore it.
- TUI: attach_session/switch fetch the profile's configured model (first of
  profile.model) via api.get_profile_model so the panel shows a value before
  the first request; model_info then refines it to the actually-served model.
  Not forwarded to the chat panel. raw CLI prints "[model] ...".

Co-Authored-By: Claude <noreply@anthropic.com>

FallbackOllamaBackend: do not blacklist single server, empty file fallback ...

- When only one Ollama server is configured, LLMConnectionError no longer
  adds it to the dead-server blacklist. This fixes the bug where a
  transient failure permanently blocked all requests until server restart.
- LLMModelNotFoundError on a single server is also not blacklisted.
- _discover_backends now falls back to settings.ollama_host when the
  ollama_backends_file is empty, missing, or returns no valid servers.
- Added unit tests covering single-server no-blacklist, multi-server
  blacklist, model-not-found no-blacklist, and empty-file fallback.

400 passed, 1 skipped

Make Settings immutable (frozen=True) and fix all test mutations ...

- Add frozen=True to SettingsConfigDict in navi/config.py
- Convert model_validator to mode="before" since mode="after" cannot mutate frozen instances
- Replace all field-level monkeypatches in tests with whole-Settings object replacement
- Ensure cross-module settings consistency (content_store, session_files, share_file, content_publish, filesystem)

392 passed, 1 skipped

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Fix ollama_backends / FallbackOllamaBackend issues ...

- registry.py: always use FallbackOllamaBackend (unified backend).
  Enables model priority lists in all deployments, not just multi-server.
- agent.py: add missing think=profile.think_enabled to run() (REST endpoint).
- compressor.py: fix model param type (str → list[str] | str | None).
- fallback.py: harden load_servers_from_file against missing/bad JSON files
  and entries without host. Add clear_blacklists() for manual reset.
- admin.py: add POST /admin/ollama/clear-blacklists endpoint.
- tech_debt_review: document dead stream() methods.
- tests: add tests for single-server fallback, bad file handling,
  missing host skipping, and blacklist clearing.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Improve content publishing UX

Add regression tests for content publishing and LLM timeouts

Align Ollama HTTP timeout with LLM timeouts