show the model that answered instead of the bare harness string

the picker rendered the literal `claude-code` for any chat that named no
tier. that is DEFAULT_MODEL — the bare harness — and it routes correctly
(no --model is passed, so the cli picks for itself) but names no catalogue
entry, so radix matched no item and the fallback from 773f0e1c printed the
raw string's last segment.

officer cannot answer this because it deliberately did not choose. the
harness does, in its system.init `model` field, which the parser was
discarding. so: emit it as a `model:resolved` chat event, translate it to an
officer id in turn-stream, and forward it to the client only when the turn
named no tier.

that last condition is the load-bearing one. the alias map is lossy in one
direction — opus[1m] and opusplan both answer as claude-opus-5 — so
forwarding unconditionally would silently relabel a user's own choice as
plain opus.

display only, and three ways: not durable (like session:claude), never
recorded to chat_session_models, and never written into the client's
selectedModel or the reattach ref. storing it would pin a session to
whatever the cli defaulted to on its first turn, which is the freedom the
bare harness exists to preserve.

untested against a live turn — the parser and translator have unit tests,
the websocket gate does not.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/servers/sidecar/claude/turn-stream.ts

@@ -1,4 +1,5 @@
 import type { ChatEvent, TurnMessage } from '../../api/chat/types';
+import { officerModelForApiModel } from '../../api/chat/model-aliases';
 
 // Translation from a harness's ChatEvent stream to the browser-facing turn messages, moved here from the
 // main server (it was `createEventHandler` in `chat/websocket.ts`, once per harness). Both the agent and
@@ -150,6 +151,18 @@ export function createTurnStream(sessionId: string): TurnStream {
           },
         ];
 
+      case 'model:resolved': {
+        // Not durable and not flushed: it says nothing about WHERE in the conversation anything happened,
+        // only what the harness is running. `session:claude` is the same shape for the same reason.
+        //
+        // A null mapping is dropped rather than forwarded raw. `<synthetic>`, mythos and every OpenCode id
+        // resolve to null, and offering the picker a model this machine may not reach is worse than
+        // leaving it as it was.
+        const officerId = officerModelForApiModel(event.apiModel);
+        if (!officerId) return [];
+        return [{ msg: { type: 'model:resolved', model: officerId }, durable: false }];
+      }
+
       case 'plan:mode':
         // Flushed like `model:switched`, and for the same reason: the marker's job is to say WHERE in the
         // conversation the rules changed, which is worthless if it lands mid-paragraph.