2. Session override (set by sending a directive-only message).

3. Per-agent default (`agents.list[].thinkingDefault` in config).

4. Global default (`agents.defaults.thinkingDefault` in config).

5. Fallback: provider-declared default when available, `low` for other catalog models marked reasoning-capable, `off` otherwise.

5. Fallback: provider-declared default when available; otherwise reasoning-capable models resolve to `medium` or the nearest supported non-`off` level for that model, and non-reasoning models stay `off`.

## Setting a session default

- The web chat thinking selector mirrors the session's stored level from the inbound session store/config when the page loads.

- Picking another level writes the session override immediately via `sessions.patch`; it does not wait for the next send and it is not a one-shot `thinkingOnce` override.

- The first option is always `Default (<resolved level>)`, where the resolved default comes from the active session model's provider thinking profile.

- The first option is always `Default (<resolved level>)`, where the resolved default comes from the active session model's provider thinking profile plus the same fallback logic that `/status` and `session_status` use.

- The picker uses `thinkingOptions` returned by the gateway session row. The browser UI does not keep its own provider regex list; plugins own model-specific level sets.

- `/think:<level>` still works and updates the same stored session level, so chat directives and the picker stay in sync.