Bug Description

After changing agents.defaults.model.primary to anthropic/claude-sonnet-4-5, the gateway continues to use anthropic/claude-opus-4-5 even after restart and /new session.

Steps to Reproduce

1. Set agents.defaults.model.primary to anthropic/claude-sonnet-4-5 via config.patch or direct file edit
2. Restart gateway
3. Start new session with /new
4. Check session_status - still shows old model
   Evidence

Config (verified via gateway config.get):
"primary": "anthropic/claude-sonnet-4-5"
Runtime: model=anthropic/claude-opus-4-5

Environment

• Clawdbot: 2026.1.24-3
• Runtime: Cloudflare Cloudchamber