Bug type

Behavior bug (incorrect state without crash)

Summary

When a session-level model override is set via /model, it persists in the session store across gateway restarts. After changing the default model in openclaw.json and restarting, existing (and even /new-ed) sessions still use the stale override instead of the updated config default.

Steps to reproduce

1. In a DM session, pin a model: /model newapi/gpt-5.4
2. Verify with /status — shows newapi/gpt-5.4
3. Edit openclaw.json, change agents.defaults.model.primary (or agent-level model) to openrouter/xiaomi/mimo-v2-pro
4. Restart gateway (openclaw gateway restart)
5. In the same DM session, run /status — still shows newapi/gpt-5.4 (stale override)
6. Run /new — the new session also inherits or retains the old override instead of the new config default

Expected behavior

After changing the default model in config and restarting gateway:

• Existing sessions should either respect the new default OR clearly indicate they have a session-level override
• /new should create a fresh session with no override, picking up the new config default
• At minimum, there should be a way to clear all session model overrides

Actual behavior

modelOverride in ~/.openclaw/agents/main/sessions/sessions.json persists across restarts with highest precedence. The config default change is effectively invisible to any session that was ever touched by /model.

Root cause

Session-level modelOverride is stored in the session store and survives gateway restarts. Model resolution order gives session override higher precedence than config defaults, with no mechanism to clear stale overrides after config changes.

Impact

• Users changing their default model in config expect the change to take effect, but it silently doesn't for existing sessions
• No CLI or chat command to bulk-clear session model overrides
• Related to Cron isolated jobs ignore payload.model and keep stale session model override #33577 (cron case) but affects all regular sessions too

Suggested fix

1. On /new: always start fresh without inheriting modelOverride from the previous session
2. Model resolution precedence: consider making config-specified model higher priority than stale session overrides, or add an explicit "clear override" mechanism
3. Visibility: /status should clearly distinguish between "using config default" and "using session override" so users can tell when an override is active
4. Bulk reset: add a command like /model reset or /model inherit to clear session-level override and fall back to config

Related issues

• Cron isolated jobs ignore payload.model and keep stale session model override #33577 (cron isolated jobs keep stale session model override)
• Model override in cron agentTurn payload is ignored — falls back to default model #47381 (model override in cron agentTurn payload ignored)
• [Bug]: Control UI model switcher sends wrong provider prefix for cross-provider model switching #50050 (Control UI model switcher wrong provider prefix)