WebShell Qwen 3.8 reasoning controls

Goal

Expose Thinking and effort controls for the exact qwen3.8-max model in the WebShell model popover. Acknowledged changes apply to subsequent live-session requests.

Design

A small agent-side model manifest declares that qwen3.8-max supports Thinking and the native effort values low, medium, and xhigh, with xhigh as its display default. The manifest is matched by exact model id and does not apply to preview, dated, aliased, or runtime models.

The agent projects that entry through ACP's existing reasoning_effort configuration option. For this model only, the option contains none plus the three manifest values. WebShell renders none as Thinking off and renders the remaining values as effort choices. No second effort configuration id is introduced.

WebShell retains PR #8675's interaction design: the current reasoning state is shown as a suffix on the model chip, reasoning options occupy the first model popover, and model search is opened from its Model submenu.

Selecting none writes reasoning: false to the current session's live generator configuration. Selecting an effort writes that effort and enables reasoning. Reading the manifest does not inject a default into generation configuration, so sessions that never use the controls retain main's existing wire behavior.

If the live session already carries a generic effort outside the manifest (high or max), ACP preserves that value through its existing generic option and WebShell hides the model-specific controls. This avoids displaying an inaccurate tier or changing live configuration merely by opening the popover.

The daemon exposes one owner-routed config-option mutation. Its public route is restricted to reasoning_effort; the response carries fresh configOptions, which becomes the caller's authoritative UI state. No observer or broadcast is added.

Scope

Included:

• exact stable qwen3.8-max only;
• the current WebShell conversation;
• Thinking on/off and low, medium, xhigh effort;
• one browser smoke covering the rendered controls and real request payload.

Excluded:

• persistence across sessions or restarts;
• TUI, channel, provider, auth-refresh, and runtime-snapshot behavior;
• persisted/default-model semantics;
• preview, aliases, and future reasoning-control shapes;
• capability flags and cross-client model/config sync.

Compatibility

Older daemons do not advertise an option containing none, so WebShell hides the controls. Non-target models keep the existing generic ACP effort option, and clients that do not consume this option remain compatible.