fix(desktop): model chip updates after a switch (session.info republish)

[agentforce314]

The bug

Selecting a different provider/model left the composer chip showing the old model — the picker marked the new one, the chip disagreed (screenshot: picker ✓ on GPT-5.6-luna, chip still "Deepseek V4 Pro").

Why

The chip reads the live session's model (PRIMARY_SESSION_VIEW.$model = primaryField(state.model, $currentModel)), not the composer draft. The renderer's own comment states the backend "stamps model/provider on EVERY session.info" and that a switch "publishes session.info when it lands, and that is what re-syncs every surface" — but serve only emitted session.info at system/init, so the session state kept its spawn-time model forever. The optimistic $currentModel paint was shadowed by that stale session state.

The picker/chip disagreement had a second cause: _init_session_info never sent provider, and currentPickerSelection only prefers the session's selection when both model and provider are set — so the picker fell back to the catalog's (correct) current while the chip showed the session's (stale) model.

Fixes

• _init_session_info now includes provider.
• New DesktopSession.publish_session_info() — re-reads get_settings and broadcasts a full session.info (model/provider/effort/approval_mode). Awaited after config.set of model/provider/effort, so chip, picker and settings reconcile to the real post-switch state — including a cross-provider switch that lands elsewhere, or fails outright (no false "switched" display).
• Turn end schedules the same refresh. Scheduled, never awaited from the pump: the control response is routed by the pump, so awaiting there would deadlock until the 30s timeout. Tasks are tracked and cancelled on shutdown.

Verified live (real session, real backend)

• Chip goes "Deepseek V4 Flash" → "Deepseek Chat" on switch. ✓
• A failed cross-provider switch (your expired Claude OAuth) correctly keeps showing the real model instead of lying. ✓
• A full turn completes with the refresh scheduled — no deadlock, zero control timeouts. ✓

4 new pytest cases (provider in init info, switch publishes session.info, turn-end republish + explicit no-deadlock assertion); 69 desktop tests green.

🤖 Generated with Claude Code