fix(web): auto-enable default thinking effort when switching to an effort-capable model

apps/kimi-web/src/composables/client/useModelProviderState.ts

@@ -9,7 +9,7 @@ import { ref, type ComputedRef } from 'vue';
 import { getKimiWebApi } from '../../api';
 import type { AppMessage, AppModel, AppProvider, AppSession, AppSkill, ThinkingLevel } from '../../api/types';
 import { safeGetString, safeSetString, STORAGE_KEYS } from '../../lib/storage';
-import { coerceThinkingForModel } from '../../lib/modelThinking';
+import { coerceThinkingForModel, thinkingLevelForModelSwitch } from '../../lib/modelThinking';
 import type { ActivityState } from '../../types';
 import type { ExtendedState } from '../useKimiWebClient';
 
@@ -170,8 +170,11 @@ export function useModelProviderState(
    */
   async function setModel(modelId: string): Promise<void> {
     const sid = rawState.activeSessionId;
-    const nextThinking = coerceThinkingForModel(modelById(modelId), rawState.thinking);
+    const targetModel = modelById(modelId);
     const prevThinking = rawState.thinking;
+    const prevModel = sid === undefined ? undefined : rawState.sessions.find((s) => s.id === sid)?.model;
+    const isSwitch = prevModel !== modelId;
+    const nextThinking = thinkingLevelForModelSwitch(targetModel, prevThinking, isSwitch);
     if (!sid) {
       // New-session draft (onboarding composer): no backend session to update.
       // Remember the pick — startSessionAndSendPrompt applies it at create time.
@@ -181,7 +184,6 @@ export function useModelProviderState(
     }
     // Optimistic: show the chosen model immediately, but remember the previous
     // one so we can roll back if the switch never reaches the daemon.
-    const prevModel = rawState.sessions.find((s) => s.id === sid)?.model;
     updateSession(sid, (s) => ({ ...s, model: modelId }));
     if (nextThinking !== prevThinking) {
       rawState.thinking = nextThinking;

apps/kimi-web/src/lib/modelThinking.test.ts

@@ -0,0 +1,186 @@
+import { describe, expect, it } from 'vitest';
+import {
+  coerceThinkingForModel,
+  commitLevel,
+  defaultThinkingLevelFor,
+  effortLabel,
+  isThinkingOn,
+  modelThinkingAvailability,
+  segmentsFor,
+  thinkingLevelForModelSwitch,
+} from './modelThinking';
+import type { ModelThinkingInfo } from './modelThinking';
+
+function model(partial: ModelThinkingInfo): ModelThinkingInfo {
+  return partial;
+}
+
+describe('modelThinking', () => {
+  describe('modelThinkingAvailability', () => {
+    it('defaults to toggle when model is unknown', () => {
+      expect(modelThinkingAvailability(undefined)).toBe('toggle');
+    });
+
+    it('detects always_thinking capability', () => {
+      expect(modelThinkingAvailability(model({ capabilities: ['always_thinking'] }))).toBe('always-on');
+    });
+
+    it('detects thinking capability', () => {
+      expect(modelThinkingAvailability(model({ capabilities: ['thinking'] }))).toBe('toggle');
+    });
+
+    it('detects adaptive thinking', () => {
+      expect(modelThinkingAvailability(model({ adaptiveThinking: true }))).toBe('toggle');
+    });
+
+    it('marks models without thinking support as unsupported', () => {
+      expect(modelThinkingAvailability(model({ capabilities: ['vision'] }))).toBe('unsupported');
+    });
+  });
+
+  describe('defaultThinkingLevelFor', () => {
+    it('returns off for unsupported models', () => {
+      expect(defaultThinkingLevelFor(model({ capabilities: [] }))).toBe('off');
+    });
+
+    it('returns the declared default effort for effort models', () => {
+      expect(defaultThinkingLevelFor(model({ capabilities: ['thinking'], supportEfforts: ['low', 'high', 'max'], defaultEffort: 'high' }))).toBe('high');
+    });
+
+    it('falls back to the middle effort when no default is declared', () => {
+      expect(defaultThinkingLevelFor(model({ capabilities: ['thinking'], supportEfforts: ['low', 'high', 'max'] }))).toBe('high');
+      expect(defaultThinkingLevelFor(model({ capabilities: ['thinking'], supportEfforts: ['low', 'high'] }))).toBe('high');
+    });
+
+    it('returns on for boolean thinking models', () => {
+      expect(defaultThinkingLevelFor(model({ capabilities: ['thinking'] }))).toBe('on');
+    });
+  });
+
+  describe('segmentsFor', () => {
+    it('shows off/on for boolean toggle models', () => {
+      expect(segmentsFor(model({ capabilities: ['thinking'] }))).toEqual(['on', 'off']);
+    });
+
+    it('shows only on for always-on models', () => {
+      expect(segmentsFor(model({ capabilities: ['always_thinking'] }))).toEqual(['on']);
+    });
+
+    it('shows only off for unsupported models', () => {
+      expect(segmentsFor(model({ capabilities: [] }))).toEqual(['off']);
+    });
+
+    it('prefixes off to effort lists for toggle effort models', () => {
+      expect(segmentsFor(model({ capabilities: ['thinking'], supportEfforts: ['low', 'high', 'max'] }))).toEqual(['off', 'low', 'high', 'max']);
+    });
+
+    it('omits off for always-on effort models', () => {
+      expect(segmentsFor(model({ capabilities: ['always_thinking'], supportEfforts: ['low', 'high'] }))).toEqual(['low', 'high']);
+    });
+  });
+
+  describe('coerceThinkingForModel', () => {
+    it('keeps the requested level before models are loaded', () => {
+      expect(coerceThinkingForModel(undefined, 'high')).toBe('high');
+    });
+
+    it('forces unsupported models to off', () => {
+      expect(coerceThinkingForModel(model({ capabilities: [] }), 'on')).toBe('off');
+    });
+
+    it('forces always-on models to their default level', () => {
+      expect(coerceThinkingForModel(model({ capabilities: ['always_thinking'] }), 'off')).toBe('on');
+    });
+
+    it('keeps off for boolean toggle models', () => {
+      expect(coerceThinkingForModel(model({ capabilities: ['thinking'] }), 'off')).toBe('off');
+    });
+
+    it('normalizes non-off levels to on for boolean toggle models', () => {
+      expect(coerceThinkingForModel(model({ capabilities: ['thinking'] }), 'high')).toBe('on');
+    });
+
+    it('keeps declared effort levels', () => {
+      expect(coerceThinkingForModel(model({ capabilities: ['thinking'], supportEfforts: ['low', 'high', 'max'] }), 'high')).toBe('high');
+    });
+
+    it('falls back to default effort for undeclared effort levels', () => {
+      expect(coerceThinkingForModel(model({ capabilities: ['thinking'], supportEfforts: ['low', 'high', 'max'] }), 'medium')).toBe('high');
+    });
+
+    it('keeps off for effort models by default', () => {
+      expect(coerceThinkingForModel(model({ capabilities: ['thinking'], supportEfforts: ['low', 'high', 'max'] }), 'off')).toBe('off');
+    });
+  });
+
+  const effortModel = model({ capabilities: ['thinking'], supportEfforts: ['low', 'high', 'max'], defaultEffort: 'high' });
+  const booleanModel = model({ capabilities: ['thinking'] });
+  const alwaysOnModel = model({ capabilities: ['always_thinking'] });
+  const unsupportedModel = model({ capabilities: [] });
+
+  describe('thinkingLevelForModelSwitch', () => {
+
+    it('auto-enables default effort when switching onto an effort model from off', () => {
+      expect(thinkingLevelForModelSwitch(effortModel, 'off', true)).toBe('high');
+    });
+
+    it('keeps off when re-selecting the current effort model', () => {
+      expect(thinkingLevelForModelSwitch(effortModel, 'off', false)).toBe('off');
+    });
+
+    it('coerces carried-over levels for effort models during a switch', () => {
+      expect(thinkingLevelForModelSwitch(effortModel, 'high', true)).toBe('high');
+      expect(thinkingLevelForModelSwitch(effortModel, 'medium', true)).toBe('high');
+    });
+
+    it('does not auto-enable for boolean models', () => {
+      expect(thinkingLevelForModelSwitch(booleanModel, 'off', true)).toBe('off');
+    });
+
+    it('still coerces boolean models to on when carried level is non-off', () => {
+      expect(thinkingLevelForModelSwitch(booleanModel, 'high', true)).toBe('on');
+    });
+
+    it('forces always-on models on even during re-selection', () => {
+      expect(thinkingLevelForModelSwitch(alwaysOnModel, 'off', false)).toBe('on');
+    });
+
+    it('forces unsupported models off during a switch', () => {
+      expect(thinkingLevelForModelSwitch(unsupportedModel, 'high', true)).toBe('off');
+    });
+  });
+
+  describe('effortLabel', () => {
+    it('capitalizes effort names', () => {
+      expect(effortLabel('off')).toBe('Off');
+      expect(effortLabel('high')).toBe('High');
+      expect(effortLabel('max')).toBe('Max');
+    });
+
+    it('returns empty string as-is', () => {
+      expect(effortLabel('')).toBe('');
+    });
+  });
+
+  describe('isThinkingOn', () => {
+    it('returns false for off only', () => {
+      expect(isThinkingOn('off')).toBe(false);
+      expect(isThinkingOn('on')).toBe(true);
+      expect(isThinkingOn('high')).toBe(true);
+    });
+  });
+
+  describe('commitLevel', () => {
+    it('keeps off', () => {
+      expect(commitLevel(effortModel, 'off')).toBe('off');
+    });
+
+    it('resolves on to the model default', () => {
+      expect(commitLevel(effortModel, 'on')).toBe('high');
+    });
+
+    it('passes concrete efforts through', () => {
+      expect(commitLevel(effortModel, 'max')).toBe('max');
+    });
+  });
+});

apps/kimi-web/src/lib/modelThinking.ts

@@ -112,3 +112,21 @@ export function commitLevel(
   if (draft === 'on') return defaultThinkingLevelFor(model);
   return draft;
 }
+
+/**
+ * Thinking level to use when the user picks a model in the switcher.
+ * Mirrors the TUI model picker: switching onto a different effort-capable
+ * model from 'off' pre-selects the model's default effort, so the user sees
+ * the effort control immediately; re-selecting the current model or moving
+ * to a boolean/unsupported model just coerces the carried-over level.
+ */
+export function thinkingLevelForModelSwitch(
+  model: ModelThinkingInfo | undefined,
+  currentLevel: ThinkingLevel,
+  isSwitch: boolean,
+): ThinkingLevel {
+  if (isSwitch && currentLevel === 'off' && (model?.supportEfforts?.length ?? 0) > 0) {
+    return defaultThinkingLevelFor(model);
+  }
+  return coerceThinkingForModel(model, currentLevel);
+}