diff --git a/src/renderer/src/aiCore/legacy/clients/BaseApiClient.ts b/src/renderer/src/aiCore/legacy/clients/BaseApiClient.ts
index 92f24b4abe..5d435b9074 100644
--- a/src/renderer/src/aiCore/legacy/clients/BaseApiClient.ts
+++ b/src/renderer/src/aiCore/legacy/clients/BaseApiClient.ts
@@ -2,9 +2,10 @@ import { loggerService } from '@logger'
 import {
   getModelSupportedVerbosity,
   isFunctionCallingModel,
-  isNotSupportTemperatureAndTopP,
   isOpenAIModel,
-  isSupportFlexServiceTierModel
+  isSupportFlexServiceTierModel,
+  isSupportTemperatureModel,
+  isSupportTopPModel
 } from '@renderer/config/models'
 import { REFERENCE_PROMPT } from '@renderer/config/prompts'
 import { getLMStudioKeepAliveTime } from '@renderer/hooks/useLMStudio'
@@ -200,7 +201,7 @@ export abstract class BaseApiClient<
   }
 
   public getTemperature(assistant: Assistant, model: Model): number | undefined {
-    if (isNotSupportTemperatureAndTopP(model)) {
+    if (!isSupportTemperatureModel(model)) {
       return undefined
     }
     const assistantSettings = getAssistantSettings(assistant)
@@ -208,7 +209,7 @@ export abstract class BaseApiClient<
   }
 
   public getTopP(assistant: Assistant, model: Model): number | undefined {
-    if (isNotSupportTemperatureAndTopP(model)) {
+    if (!isSupportTopPModel(model)) {
       return undefined
     }
     const assistantSettings = getAssistantSettings(assistant)
diff --git a/src/renderer/src/aiCore/prepareParams/modelParameters.ts b/src/renderer/src/aiCore/prepareParams/modelParameters.ts
index 8a1d53a754..34c3418287 100644
--- a/src/renderer/src/aiCore/prepareParams/modelParameters.ts
+++ b/src/renderer/src/aiCore/prepareParams/modelParameters.ts
@@ -4,60 +4,81 @@
  */
 
 import {
-  isClaude45ReasoningModel,
   isClaudeReasoningModel,
   isMaxTemperatureOneModel,
-  isNotSupportTemperatureAndTopP,
   isSupportedFlexServiceTier,
-  isSupportedThinkingTokenClaudeModel
+  isSupportedThinkingTokenClaudeModel,
+  isSupportTemperatureModel,
+  isSupportTopPModel,
+  isTemperatureTopPMutuallyExclusiveModel
 } from '@renderer/config/models'
-import { getAssistantSettings, getProviderByModel } from '@renderer/services/AssistantService'
+import {
+  DEFAULT_ASSISTANT_SETTINGS,
+  getAssistantSettings,
+  getProviderByModel
+} from '@renderer/services/AssistantService'
 import type { Assistant, Model } from '@renderer/types'
 import { defaultTimeout } from '@shared/config/constant'
 
 import { getAnthropicThinkingBudget } from '../utils/reasoning'
 
 /**
- * Claude 4.5 推理模型:
- * - 只启用 temperature → 使用 temperature
- * - 只启用 top_p → 使用 top_p
- * - 同时启用 → temperature 生效,top_p 被忽略
- * - 都不启用 → 都不使用
- * 获取温度参数
+ * Retrieves the temperature parameter, adapting it based on assistant.settings and model capabilities.
+ * - Disabled for Claude reasoning models when reasoning effort is set.
+ * - Disabled for models that do not support temperature.
+ * - Disabled for Claude 4.5 reasoning models when TopP is enabled and temperature is disabled.
+ * Otherwise, returns the temperature value if the assistant has temperature enabled.
  */
 export function getTemperature(assistant: Assistant, model: Model): number | undefined {
   if (assistant.settings?.reasoning_effort && isClaudeReasoningModel(model)) {
     return undefined
   }
+
+  if (!isSupportTemperatureModel(model)) {
+    return undefined
+  }
+
   if (
-    isNotSupportTemperatureAndTopP(model) ||
-    (isClaude45ReasoningModel(model) && assistant.settings?.enableTopP && !assistant.settings?.enableTemperature)
+    isTemperatureTopPMutuallyExclusiveModel(model) &&
+    assistant.settings?.enableTopP &&
+    !assistant.settings?.enableTemperature
   ) {
     return undefined
   }
+
   const assistantSettings = getAssistantSettings(assistant)
   let temperature = assistantSettings?.temperature
   if (temperature && isMaxTemperatureOneModel(model)) {
     temperature = Math.min(1, temperature)
   }
-  return assistantSettings?.enableTemperature ? temperature : undefined
+
+  // FIXME: assistant.settings.enableTemperature should be always a boolean value.
+  const enableTemperature = assistantSettings?.enableTemperature ?? DEFAULT_ASSISTANT_SETTINGS.enableTemperature
+  return enableTemperature ? temperature : undefined
 }
 
 /**
- * 获取 TopP 参数
+ * Retrieves the TopP parameter, adapting it based on assistant.settings and model capabilities.
+ * - Disabled for Claude reasoning models when reasoning effort is set.
+ * - Disabled for models that do not support TopP.
+ * - Disabled for Claude 4.5 reasoning models when temperature is explicitly enabled.
+ * Otherwise, returns the TopP value if the assistant has TopP enabled.
  */
 export function getTopP(assistant: Assistant, model: Model): number | undefined {
   if (assistant.settings?.reasoning_effort && isClaudeReasoningModel(model)) {
     return undefined
   }
-  if (
-    isNotSupportTemperatureAndTopP(model) ||
-    (isClaude45ReasoningModel(model) && assistant.settings?.enableTemperature)
-  ) {
+  if (!isSupportTopPModel(model)) {
     return undefined
   }
+  if (isTemperatureTopPMutuallyExclusiveModel(model) && assistant.settings?.enableTemperature) {
+    return undefined
+  }
+
   const assistantSettings = getAssistantSettings(assistant)
-  return assistantSettings?.enableTopP ? assistantSettings?.topP : undefined
+  // FIXME: assistant.settings.enableTopP should be always a boolean value.
+  const enableTopP = assistantSettings.enableTopP ?? DEFAULT_ASSISTANT_SETTINGS.enableTopP
+  return enableTopP ? assistantSettings?.topP : undefined
 }
 
 /**
diff --git a/src/renderer/src/config/models/__tests__/utils.test.ts b/src/renderer/src/config/models/__tests__/utils.test.ts
index ae4e33875c..042673b75d 100644
--- a/src/renderer/src/config/models/__tests__/utils.test.ts
+++ b/src/renderer/src/config/models/__tests__/utils.test.ts
@@ -25,11 +25,13 @@ import {
   isGenerateImageModels,
   isMaxTemperatureOneModel,
   isNotSupportSystemMessageModel,
-  isNotSupportTemperatureAndTopP,
   isNotSupportTextDeltaModel,
   isSupportedFlexServiceTier,
   isSupportedModel,
   isSupportFlexServiceTierModel,
+  isSupportTemperatureModel,
+  isSupportTopPModel,
+  isTemperatureTopPMutuallyExclusiveModel,
   isVisionModels,
   isZhipuModel
 } from '../utils'
@@ -273,27 +275,104 @@ describe('model utils', () => {
   })
 
   describe('Temperature and top-p support', () => {
-    describe('isNotSupportTemperatureAndTopP', () => {
-      it('returns true for reasoning models', () => {
+    describe('isSupportTemperatureModel', () => {
+      it('returns false for reasoning models (non-open weight)', () => {
         const model = createModel({ id: 'o1' })
         reasoningMock.mockReturnValue(true)
-        expect(isNotSupportTemperatureAndTopP(model)).toBe(true)
+        expect(isSupportTemperatureModel(model)).toBe(false)
       })
 
-      it('returns false for open weight models', () => {
+      it('returns true for open weight models', () => {
         const openWeight = createModel({ id: 'gpt-oss-debug' })
-        expect(isNotSupportTemperatureAndTopP(openWeight)).toBe(false)
+        expect(isSupportTemperatureModel(openWeight)).toBe(true)
       })
 
-      it('returns true for chat-only models without reasoning', () => {
+      it('returns false for chat-only models', () => {
         const chatOnly = createModel({ id: 'o1-preview' })
-        reasoningMock.mockReturnValue(false)
-        expect(isNotSupportTemperatureAndTopP(chatOnly)).toBe(true)
+        expect(isSupportTemperatureModel(chatOnly)).toBe(false)
       })
 
-      it('returns true for Qwen MT models', () => {
+      it('returns false for Qwen MT models', () => {
         const qwenMt = createModel({ id: 'qwen-mt-large', provider: 'aliyun' })
-        expect(isNotSupportTemperatureAndTopP(qwenMt)).toBe(true)
+        expect(isSupportTemperatureModel(qwenMt)).toBe(false)
+      })
+
+      it('returns false for null/undefined models', () => {
+        expect(isSupportTemperatureModel(null)).toBe(false)
+        expect(isSupportTemperatureModel(undefined)).toBe(false)
+      })
+
+      it('returns true for regular GPT models', () => {
+        const model = createModel({ id: 'gpt-4' })
+        expect(isSupportTemperatureModel(model)).toBe(true)
+      })
+    })
+
+    describe('isSupportTopPModel', () => {
+      it('returns false for reasoning models (non-open weight)', () => {
+        const model = createModel({ id: 'o1' })
+        reasoningMock.mockReturnValue(true)
+        expect(isSupportTopPModel(model)).toBe(false)
+      })
+
+      it('returns true for open weight models', () => {
+        const openWeight = createModel({ id: 'gpt-oss-debug' })
+        expect(isSupportTopPModel(openWeight)).toBe(true)
+      })
+
+      it('returns false for chat-only models', () => {
+        const chatOnly = createModel({ id: 'o1-preview' })
+        expect(isSupportTopPModel(chatOnly)).toBe(false)
+      })
+
+      it('returns false for Qwen MT models', () => {
+        const qwenMt = createModel({ id: 'qwen-mt-large', provider: 'aliyun' })
+        expect(isSupportTopPModel(qwenMt)).toBe(false)
+      })
+
+      it('returns false for null/undefined models', () => {
+        expect(isSupportTopPModel(null)).toBe(false)
+        expect(isSupportTopPModel(undefined)).toBe(false)
+      })
+
+      it('returns true for regular GPT models', () => {
+        const model = createModel({ id: 'gpt-4' })
+        expect(isSupportTopPModel(model)).toBe(true)
+      })
+    })
+
+    describe('isTemperatureTopPMutuallyExclusiveModel', () => {
+      it('returns true for Claude 4.5 reasoning models', () => {
+        const claude45Sonnet = createModel({ id: 'claude-sonnet-4.5-20250514' })
+        expect(isTemperatureTopPMutuallyExclusiveModel(claude45Sonnet)).toBe(true)
+
+        const claude45Opus = createModel({ id: 'claude-opus-4.5-20250514' })
+        expect(isTemperatureTopPMutuallyExclusiveModel(claude45Opus)).toBe(true)
+      })
+
+      it('returns false for Claude 4 models', () => {
+        const claude4Sonnet = createModel({ id: 'claude-sonnet-4-20250514' })
+        expect(isTemperatureTopPMutuallyExclusiveModel(claude4Sonnet)).toBe(false)
+      })
+
+      it('returns false for Claude 3.x models', () => {
+        const claude35Sonnet = createModel({ id: 'claude-3-5-sonnet-20241022' })
+        expect(isTemperatureTopPMutuallyExclusiveModel(claude35Sonnet)).toBe(false)
+
+        const claude3Opus = createModel({ id: 'claude-3-opus-20240229' })
+        expect(isTemperatureTopPMutuallyExclusiveModel(claude3Opus)).toBe(false)
+      })
+
+      it('returns false for other AI models', () => {
+        expect(isTemperatureTopPMutuallyExclusiveModel(createModel({ id: 'gpt-4o' }))).toBe(false)
+        expect(isTemperatureTopPMutuallyExclusiveModel(createModel({ id: 'o1' }))).toBe(false)
+        expect(isTemperatureTopPMutuallyExclusiveModel(createModel({ id: 'gemini-2.0-flash' }))).toBe(false)
+        expect(isTemperatureTopPMutuallyExclusiveModel(createModel({ id: 'qwen-max' }))).toBe(false)
+      })
+
+      it('returns false for null/undefined models', () => {
+        expect(isTemperatureTopPMutuallyExclusiveModel(null)).toBe(false)
+        expect(isTemperatureTopPMutuallyExclusiveModel(undefined)).toBe(false)
       })
     })
   })
diff --git a/src/renderer/src/config/models/utils.ts b/src/renderer/src/config/models/utils.ts
index 625a5b5c63..9ae8defa7a 100644
--- a/src/renderer/src/config/models/utils.ts
+++ b/src/renderer/src/config/models/utils.ts
@@ -14,6 +14,7 @@ import {
   isSupportVerbosityModel
 } from './openai'
 import { isQwenMTModel } from './qwen'
+import { isClaude45ReasoningModel } from './reasoning'
 import { isGenerateImageModel, isTextToImageModel, isVisionModel } from './vision'
 export const NOT_SUPPORTED_REGEX = /(?:^tts|whisper|speech)/i
 export const GEMINI_FLASH_MODEL_REGEX = new RegExp('gemini.*-flash.*$', 'i')
@@ -42,20 +43,71 @@ export function isSupportedModel(model: OpenAI.Models.Model): boolean {
   return !NOT_SUPPORTED_REGEX.test(modelId)
 }
 
-export function isNotSupportTemperatureAndTopP(model: Model): boolean {
+/**
+ * Check if the model supports temperature parameter
+ * @param model - The model to check
+ * @returns true if the model supports temperature parameter
+ */
+export function isSupportTemperatureModel(model: Model | undefined | null): boolean {
   if (!model) {
-    return true
+    return false
   }
 
-  if (
-    (isOpenAIReasoningModel(model) && !isOpenAIOpenWeightModel(model)) ||
-    isOpenAIChatCompletionOnlyModel(model) ||
-    isQwenMTModel(model)
-  ) {
-    return true
+  // OpenAI reasoning models (except open weight) don't support temperature
+  if (isOpenAIReasoningModel(model) && !isOpenAIOpenWeightModel(model)) {
+    return false
   }
 
-  return false
+  // OpenAI chat completion only models don't support temperature
+  if (isOpenAIChatCompletionOnlyModel(model)) {
+    return false
+  }
+
+  // Qwen MT models don't support temperature
+  if (isQwenMTModel(model)) {
+    return false
+  }
+
+  return true
+}
+
+/**
+ * Check if the model supports top_p parameter
+ * @param model - The model to check
+ * @returns true if the model supports top_p parameter
+ */
+export function isSupportTopPModel(model: Model | undefined | null): boolean {
+  if (!model) {
+    return false
+  }
+
+  // OpenAI reasoning models (except open weight) don't support top_p
+  if (isOpenAIReasoningModel(model) && !isOpenAIOpenWeightModel(model)) {
+    return false
+  }
+
+  // OpenAI chat completion only models don't support top_p
+  if (isOpenAIChatCompletionOnlyModel(model)) {
+    return false
+  }
+
+  // Qwen MT models don't support top_p
+  if (isQwenMTModel(model)) {
+    return false
+  }
+
+  return true
+}
+
+/**
+ * Check if the model enforces mutual exclusivity between temperature and top_p parameters.
+ * Currently only Claude 4.5 reasoning models require this constraint.
+ * @param model - The model to check
+ * @returns true if temperature and top_p are mutually exclusive for this model
+ */
+export function isTemperatureTopPMutuallyExclusiveModel(model: Model | undefined | null): boolean {
+  if (!model) return false
+  return isClaude45ReasoningModel(model)
 }
 
 export function isGemmaModel(model?: Model): boolean {
diff --git a/src/renderer/src/services/AssistantService.ts b/src/renderer/src/services/AssistantService.ts
index 96881c56b6..589fd7b6c8 100644
--- a/src/renderer/src/services/AssistantService.ts
+++ b/src/renderer/src/services/AssistantService.ts
@@ -27,7 +27,7 @@ import { uuid } from '@renderer/utils'
 
 const logger = loggerService.withContext('AssistantService')
 
-export const DEFAULT_ASSISTANT_SETTINGS: AssistantSettings = {
+export const DEFAULT_ASSISTANT_SETTINGS = {
   temperature: DEFAULT_TEMPERATURE,
   enableTemperature: true,
   contextCount: DEFAULT_CONTEXTCOUNT,
@@ -39,7 +39,7 @@ export const DEFAULT_ASSISTANT_SETTINGS: AssistantSettings = {
   // It would gracefully fallback to prompt if not supported by model.
   toolUseMode: 'function',
   customParameters: []
-} as const
+} as const satisfies AssistantSettings
 
 export function getDefaultAssistant(): Assistant {
   return {