The route a new session starts from was frozen into the gateway's
composition entry, so switching models in a conversation reached only that
conversation and every later session went back to the shipped default.
The gateway now owns an `api-gateway` settings section: the entry is the
base layer and the user document layers over it, so `session.selectModel`
records an accepted switch as the default for the next session. The write
is wholesale rather than a merge — switching to a model with no reasoning
effort has to clear a stored one — and a storage failure is reported
without undoing the switch, which already applies to its own session.
`targetFor` now resolves its tiers on every read instead of seeding once:
an explicit selection, else the session's own logged request header, else
the live default. That is what keeps a session that has run a turn deriving
its route from its log forever after, while a session still blank — New
Session reuses one rather than minting another — starts from a default
saved after it was created.
Steer, inject, and followup now land as durable user/message events on the
session surface; the steering/message event type and its ConversationNode
kind are removed from the client projection. Update tests, docs, generated
catalogs, and agent notes to match, and align the steering e2e fixture and
prompt inventory assertions with the durable user/message landing.
Conflict resolutions:
- `session.list`: master's projection columns fold into the PR's cancellable,
batched `listVisibleSessionSummaries`, which `session.search` shares as its
visibility baseline; master's goal helpers stay beside it.
- Client sessions face: master narrowed `ctx.sessions` to `ISessions`, so the
search verb and its protocol-constant bound are declared there and the
test-runtime double implements them (recorded, empty page unless a scenario
stubs hits).
- `WorkspaceBrowser`: master's per-row Rename wiring rides the PR's search
results view; the tree keeps the PR's query-free derivations.
- `dsh web` bin: the PR's shutdown-handlers-before-readiness order with
master's boot-time LAN address snapshot.
- `session-query-sqlite`: master's `SCHEMA_VERSION` 7 stands; the PR's bump
carried no schema change.
- Specs: master wraps assistant/steering message payloads and requires an
`application/json` carrier request, so the search fixtures and tests follow.
- Web aria goldens keep master's recording plus the PR's search placeholder;
the navigation-panes inventory keeps master's terminal-card golden next to
the PR's search-results golden.
