A manual composer pick stays sticky across new chats (intended), but if that
model later disappears from the provider/config, every new chat kept trying the
dead model and 404'd. Fall back to the profile default in that one case only.
refreshCurrentModel now consults the model-options cache the composer already
populates (no extra fetch): a manual pick is preserved unless manualPickRemoved()
proves it's gone — provider present, non-empty catalog, model absent. An
unknown/absent provider, an empty (re-auth/unconfigured) list, or a not-yet-loaded
catalog all preserve the pick, so a still-valid selection is never clobbered.
Both Desktop picker surfaces (status-bar model menu, settings/onboarding
dialog) only asked the connected gateway's model.options once a session
existed; before that they fell back to the Desktop REST/global options, which
can't see virtual providers a remote gateway exposes — including the MoA
presets from #53817. Centralize the fetch rule in requestModelOptions(): prefer
the connected gateway whenever one exists (no session_id needed — the RPC
resolves disk config), REST only when no gateway is connected.
The status-bar MoA preset section now renders from the same model.options
payload (the virtual `moa` provider row) instead of the local /api/model/moa
REST config, so remote presets appear correctly; the row is filtered out of
the main provider groups so presets don't list twice. Preset selection keeps
the persistent switchTo path from #56417 and drops the vestigial session gate —
like regular model rows, a pre-session pick ships on the next session.create.
Fixes#53817.
Rebased and reconciled with #56417 (persistent MoA selection), which landed
after this PR was opened and covered its one-shot-/moa half.
