diff --git a/electron/main/ai/llm/index.ts b/electron/main/ai/llm/index.ts
index 69755ba5..4ce77802 100644
--- a/electron/main/ai/llm/index.ts
+++ b/electron/main/ai/llm/index.ts
@@ -13,7 +13,7 @@ import { aiLogger } from '../logger'
 import { resolveApiKey, writeAuthProfile } from '@openchatlab/config'
 import { buildChatLabUserAgentHeaders } from '../../utils/httpHeaders'
 import { t } from '../../i18n'
-import { completeSimple, type PiModel, type PiApi } from '@openchatlab/node-runtime'
+import { completeSimple, buildPiModel as buildPiModelCore, type PiModel, type PiApi } from '@openchatlab/node-runtime'
 
 // 新模型系统导出
 export { BUILTIN_PROVIDERS, getBuiltinProviderById } from './provider-registry'
@@ -424,106 +424,13 @@ export function getProviderInfo(provider: LLMProvider): ProviderInfo | null {
 
 // ==================== pi-ai Model 构建 ====================
 
-/**
- * 规范化 Anthropic baseUrl：Anthropic SDK 内部会拼接 /v1/messages，
- * 因此 baseUrl 不应包含 /v1 后缀，否则会导致 /v1/v1/messages 双重路径。
- */
-function normalizeAnthropicBaseUrl(url: string): string {
-  return url.replace(/\/v1\/?$/, '')
-}
-
-/**
- * 规范化 OpenAI Compatible baseUrl：
- * 用户经常忘记在域名后加 /v1，OpenAI SDK 不会自动补全。
- * 如果 URL 没有以 /v1 结尾且路径部分为空或仅有 /，自动补上。
- * 已有具体路径（如 /api/v1、/proxy）的不做修改。
- */
-function normalizeOpenAICompatibleBaseUrl(url: string): string {
-  if (!url) return url
-  const trimmed = url.replace(/\/+$/, '')
-  if (trimmed.endsWith('/v1')) return trimmed
-  try {
-    const parsed = new URL(trimmed)
-    // 仅当路径为空或 "/" 时补全 /v1，避免破坏已有的自定义路径
-    if (parsed.pathname === '/' || parsed.pathname === '') {
-      return trimmed + '/v1'
-    }
-  } catch {
-    // URL 解析失败，不做处理
-  }
-  return trimmed
-}
-
-const DEFAULT_CONTEXT_WINDOW = 128000
-
 export function buildPiModel(config: AIServiceConfig): PiModel<PiApi> {
-  const providerDef = getBuiltinProviderById(config.provider)
-  const providerInfo = getProviderInfo(config.provider)
-  const baseUrl = config.baseUrl || providerDef?.defaultBaseUrl || providerInfo?.defaultBaseUrl || ''
-  const modelId = config.model || providerInfo?.models?.[0]?.id || ''
+  validateProviderBaseUrl(config.provider, config.baseUrl)
 
-  validateProviderBaseUrl(config.provider, baseUrl)
-
-  const modelDef = findModelDefinition(config.provider, modelId)
-  const contextWindow = modelDef?.contextWindow ?? DEFAULT_CONTEXT_WINDOW
-
-  const BUILTIN_PROVIDER_API: Record<string, PiApi> = {
-    gemini: 'google-generative-ai',
-    anthropic: 'anthropic-messages',
-  }
-
-  const apiFormat: PiApi = (config.apiFormat as PiApi) || BUILTIN_PROVIDER_API[config.provider] || 'openai-completions'
-
-  if (apiFormat === 'google-generative-ai') {
-    return {
-      id: modelId,
-      name: modelId,
-      api: 'google-generative-ai',
-      provider: 'google',
-      baseUrl,
-      reasoning: false,
-      input: ['text'],
-      cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
-      contextWindow,
-      maxTokens: config.maxTokens ?? 8192,
-    }
-  }
-
-  if (apiFormat === 'anthropic-messages') {
-    return {
-      id: modelId,
-      name: modelId,
-      api: 'anthropic-messages',
-      provider: 'anthropic',
-      baseUrl: normalizeAnthropicBaseUrl(baseUrl),
-      reasoning: false,
-      input: ['text'],
-      cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
-      contextWindow,
-      maxTokens: config.maxTokens ?? 8192,
-    }
-  }
-
-  // openai-compatible + openai-completions/openai-responses：自动补全 /v1（用户经常忘记）
-  const resolvedBaseUrl =
-    config.provider === 'openai-compatible' && (apiFormat === 'openai-completions' || apiFormat === 'openai-responses')
-      ? normalizeOpenAICompatibleBaseUrl(baseUrl)
-      : baseUrl
-
-  return {
-    id: modelId,
-    name: modelId,
-    api: apiFormat,
-    provider: config.provider,
-    baseUrl: resolvedBaseUrl,
+  return buildPiModelCore(config, {
+    findModelFn: findModelDefinition,
     headers: config.provider === 'openai-compatible' ? buildChatLabUserAgentHeaders() : undefined,
-    reasoning: config.isReasoningModel ?? false,
-    input: ['text'],
-    cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
-    contextWindow,
-    maxTokens: config.maxTokens ?? 4096,
-    compat: config.disableThinking ? { thinkingFormat: 'qwen' } : undefined,
-  }
+  })
 }
 
 // ==================== 远程模型列表获取 ====================
diff --git a/packages/node-runtime/src/ai/__tests__/llm-builder.test.ts b/packages/node-runtime/src/ai/__tests__/llm-builder.test.ts
new file mode 100644
index 00000000..b64d29fe
--- /dev/null
+++ b/packages/node-runtime/src/ai/__tests__/llm-builder.test.ts
@@ -0,0 +1,129 @@
+import assert from 'node:assert/strict'
+import { describe, it } from 'node:test'
+import { buildPiModel, normalizeAnthropicBaseUrl, normalizeOpenAICompatibleBaseUrl } from '../llm-builder'
+
+describe('normalizeAnthropicBaseUrl', () => {
+  it('strips trailing /v1', () => {
+    assert.equal(normalizeAnthropicBaseUrl('https://api.anthropic.com/v1'), 'https://api.anthropic.com')
+  })
+
+  it('strips trailing /v1/', () => {
+    assert.equal(normalizeAnthropicBaseUrl('https://api.anthropic.com/v1/'), 'https://api.anthropic.com')
+  })
+
+  it('leaves URL without /v1 unchanged', () => {
+    assert.equal(normalizeAnthropicBaseUrl('https://api.anthropic.com'), 'https://api.anthropic.com')
+  })
+})
+
+describe('normalizeOpenAICompatibleBaseUrl', () => {
+  it('appends /v1 when path is empty', () => {
+    assert.equal(normalizeOpenAICompatibleBaseUrl('https://api.example.com'), 'https://api.example.com/v1')
+  })
+
+  it('appends /v1 when path is /', () => {
+    assert.equal(normalizeOpenAICompatibleBaseUrl('https://api.example.com/'), 'https://api.example.com/v1')
+  })
+
+  it('does not append when already ends with /v1', () => {
+    assert.equal(normalizeOpenAICompatibleBaseUrl('https://api.example.com/v1'), 'https://api.example.com/v1')
+  })
+
+  it('does not modify URLs with custom paths', () => {
+    assert.equal(normalizeOpenAICompatibleBaseUrl('https://api.example.com/proxy'), 'https://api.example.com/proxy')
+  })
+
+  it('returns empty string for empty input', () => {
+    assert.equal(normalizeOpenAICompatibleBaseUrl(''), '')
+  })
+})
+
+describe('buildPiModel', () => {
+  it('builds a Google Generative AI model', () => {
+    const model = buildPiModel({
+      provider: 'gemini',
+      model: 'gemini-2.0-flash',
+      baseUrl: 'https://generativelanguage.googleapis.com',
+    })
+    assert.equal(model.api, 'google-generative-ai')
+    assert.equal(model.provider, 'google')
+    assert.equal(model.id, 'gemini-2.0-flash')
+  })
+
+  it('builds an Anthropic model with normalized URL', () => {
+    const model = buildPiModel({
+      provider: 'anthropic',
+      model: 'claude-sonnet-4-20250514',
+      baseUrl: 'https://api.anthropic.com/v1',
+    })
+    assert.equal(model.api, 'anthropic-messages')
+    assert.equal(model.baseUrl, 'https://api.anthropic.com')
+  })
+
+  it('builds an OpenAI model with default apiFormat', () => {
+    const model = buildPiModel({
+      provider: 'openai',
+      model: 'gpt-4o',
+      baseUrl: 'https://api.openai.com/v1',
+    })
+    assert.equal(model.api, 'openai-completions')
+  })
+
+  it('normalizes openai-compatible URLs', () => {
+    const model = buildPiModel({
+      provider: 'openai-compatible',
+      model: 'custom-model',
+      baseUrl: 'https://my-gateway.example.com',
+      apiFormat: 'openai-completions',
+    })
+    assert.equal(model.baseUrl, 'https://my-gateway.example.com/v1')
+  })
+
+  it('passes custom headers via options', () => {
+    const model = buildPiModel(
+      { provider: 'openai-compatible', model: 'test', baseUrl: 'https://test.com/v1' },
+      { headers: { 'X-Custom': 'value' } }
+    )
+    assert.deepEqual(model.headers, { 'X-Custom': 'value' })
+  })
+
+  it('sets compat.thinkingFormat when disableThinking is true', () => {
+    const model = buildPiModel({
+      provider: 'openai',
+      model: 'test',
+      baseUrl: 'https://api.openai.com/v1',
+      disableThinking: true,
+    })
+    assert.deepEqual(model.compat, { thinkingFormat: 'qwen' })
+  })
+
+  it('sets reasoning flag from isReasoningModel', () => {
+    const model = buildPiModel({
+      provider: 'openai',
+      model: 'o1',
+      baseUrl: 'https://api.openai.com/v1',
+      isReasoningModel: true,
+    })
+    assert.equal(model.reasoning, true)
+  })
+
+  it('uses custom findModelFn for context window', () => {
+    const model = buildPiModel(
+      { provider: 'openai', model: 'custom', baseUrl: 'https://api.openai.com/v1' },
+      {
+        findModelFn: (_providerId, _modelId) => ({
+          id: 'custom',
+          providerId: 'openai',
+          name: 'Custom',
+          contextWindow: 32000,
+          capabilities: ['chat'] as const,
+          recommendedFor: ['chat'] as const,
+          status: 'stable' as const,
+          builtin: false,
+          editable: true,
+        }),
+      }
+    )
+    assert.equal(model.contextWindow, 32000)
+  })
+})
diff --git a/packages/node-runtime/src/ai/index.ts b/packages/node-runtime/src/ai/index.ts
index 0172b2fe..540b3178 100644
--- a/packages/node-runtime/src/ai/index.ts
+++ b/packages/node-runtime/src/ai/index.ts
@@ -62,6 +62,10 @@ export type { PreprocessingPipelineOptions, PreprocessingPipelineResult } from '
 export type { AgentCoreOptions, AgentCoreEvent, AgentCoreResult, AgentTokenUsage, SimpleHistoryMessage } from './agent'
 export { runAgentCore } from './agent'
 
+// LLM Model Builder
+export { buildPiModel, normalizeAnthropicBaseUrl, normalizeOpenAICompatibleBaseUrl } from './llm-builder'
+export type { PiModelConfig, BuildPiModelOptions } from './llm-builder'
+
 // Re-exports from @mariozechner/pi-agent-core
 export type { AgentTool, AgentToolResult } from '@mariozechner/pi-agent-core'
 
diff --git a/packages/node-runtime/src/ai/llm-builder.ts b/packages/node-runtime/src/ai/llm-builder.ts
new file mode 100644
index 00000000..d6e91338
--- /dev/null
+++ b/packages/node-runtime/src/ai/llm-builder.ts
@@ -0,0 +1,128 @@
+/**
+ * Shared PiModel builder — translates an AIServiceConfig-like
+ * object into a PiModel instance for @mariozechner/pi-ai.
+ *
+ * Used by both Electron and Server to eliminate duplicated
+ * URL normalization, apiFormat mapping, and model construction.
+ */
+
+import { BUILTIN_PROVIDERS, getBuiltinModelsByProvider, BUILTIN_MODELS, type ModelDefinition } from '@openchatlab/core'
+import type { Model as PiModel, Api as PiApi } from '@mariozechner/pi-ai'
+
+export interface PiModelConfig {
+  provider: string
+  model?: string
+  baseUrl?: string
+  maxTokens?: number
+  apiFormat?: string
+  disableThinking?: boolean
+  isReasoningModel?: boolean
+}
+
+export interface BuildPiModelOptions {
+  /** Override model definition lookup (e.g. to include custom models). */
+  findModelFn?: (providerId: string, modelId: string) => ModelDefinition | null
+  /** Extra headers injected into the PiModel (e.g. User-Agent). */
+  headers?: Record<string, string>
+}
+
+/**
+ * Strip /v1 suffix from Anthropic baseUrl because the SDK
+ * internally appends /v1/messages.
+ */
+export function normalizeAnthropicBaseUrl(url: string): string {
+  return url.replace(/\/v1\/?$/, '')
+}
+
+/**
+ * Auto-append /v1 to OpenAI-compatible URLs when the path is empty
+ * (users frequently forget this).
+ */
+export function normalizeOpenAICompatibleBaseUrl(url: string): string {
+  if (!url) return url
+  const trimmed = url.replace(/\/+$/, '')
+  if (trimmed.endsWith('/v1')) return trimmed
+  try {
+    const parsed = new URL(trimmed)
+    if (parsed.pathname === '/' || parsed.pathname === '') {
+      return trimmed + '/v1'
+    }
+  } catch {
+    // URL parse failure — return as-is
+  }
+  return trimmed
+}
+
+const DEFAULT_CONTEXT_WINDOW = 128000
+
+function defaultFindModel(providerId: string, modelId: string): ModelDefinition | null {
+  const forProvider = getBuiltinModelsByProvider(providerId)
+  return forProvider.find((m) => m.id === modelId) || BUILTIN_MODELS.find((m) => m.id === modelId) || null
+}
+
+const BUILTIN_PROVIDER_API: Record<string, PiApi> = {
+  gemini: 'google-generative-ai',
+  anthropic: 'anthropic-messages',
+}
+
+export function buildPiModel(config: PiModelConfig, options?: BuildPiModelOptions): PiModel<PiApi> {
+  const providerDef = BUILTIN_PROVIDERS.find((p) => p.id === config.provider)
+  const baseUrl = config.baseUrl || providerDef?.defaultBaseUrl || ''
+  const modelId = config.model || ''
+
+  const findModel = options?.findModelFn ?? defaultFindModel
+  const modelDef = findModel(config.provider, modelId)
+  const contextWindow = modelDef?.contextWindow ?? DEFAULT_CONTEXT_WINDOW
+
+  const apiFormat: PiApi = (config.apiFormat as PiApi) || BUILTIN_PROVIDER_API[config.provider] || 'openai-completions'
+
+  if (apiFormat === 'google-generative-ai') {
+    return {
+      id: modelId,
+      name: modelId,
+      api: 'google-generative-ai',
+      provider: 'google',
+      baseUrl,
+      reasoning: false,
+      input: ['text'],
+      cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+      contextWindow,
+      maxTokens: config.maxTokens ?? 8192,
+    }
+  }
+
+  if (apiFormat === 'anthropic-messages') {
+    return {
+      id: modelId,
+      name: modelId,
+      api: 'anthropic-messages',
+      provider: 'anthropic',
+      baseUrl: normalizeAnthropicBaseUrl(baseUrl),
+      reasoning: false,
+      input: ['text'],
+      cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+      contextWindow,
+      maxTokens: config.maxTokens ?? 8192,
+    }
+  }
+
+  const resolvedBaseUrl =
+    config.provider === 'openai-compatible' && (apiFormat === 'openai-completions' || apiFormat === 'openai-responses')
+      ? normalizeOpenAICompatibleBaseUrl(baseUrl)
+      : baseUrl
+
+  return {
+    id: modelId,
+    name: modelId,
+    api: apiFormat,
+    provider: config.provider,
+    baseUrl: resolvedBaseUrl,
+    headers: options?.headers,
+    reasoning: config.isReasoningModel ?? false,
+    input: ['text'],
+    cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
+    contextWindow,
+    maxTokens: config.maxTokens ?? 4096,
+    compat: config.disableThinking ? { thinkingFormat: 'qwen' } : undefined,
+  }
+}
diff --git a/packages/node-runtime/src/index.ts b/packages/node-runtime/src/index.ts
index 413bb8fd..55cf7f19 100644
--- a/packages/node-runtime/src/index.ts
+++ b/packages/node-runtime/src/index.ts
@@ -86,6 +86,10 @@ export type {
 export type { AgentCoreOptions, AgentCoreEvent, AgentCoreResult, AgentTokenUsage, SimpleHistoryMessage } from './ai'
 export { runAgentCore } from './ai'
 
+// LLM Model Builder
+export { buildPiModel, normalizeAnthropicBaseUrl, normalizeOpenAICompatibleBaseUrl } from './ai'
+export type { PiModelConfig, BuildPiModelOptions } from './ai'
+
 // Re-exports: @mariozechner/pi-agent-core & @mariozechner/pi-ai
 export type { AgentTool, AgentToolResult } from './ai'
 export { Type, completeSimple, streamSimple } from './ai'
diff --git a/packages/server/src/ai/llm-config.ts b/packages/server/src/ai/llm-config.ts
index e884b167..0f23a038 100644
--- a/packages/server/src/ai/llm-config.ts
+++ b/packages/server/src/ai/llm-config.ts
@@ -10,8 +10,7 @@
 import * as fs from 'fs'
 import * as path from 'path'
 import type { PiModel, PiApi } from '@openchatlab/node-runtime'
-import { BUILTIN_PROVIDERS, getBuiltinModelsByProvider, BUILTIN_MODELS } from '@openchatlab/core'
-import type { ModelDefinition } from '@openchatlab/core'
+import { buildPiModel as buildPiModelCore, type PiModelConfig } from '@openchatlab/node-runtime'
 import { resolveApiKey, writeAuthProfile } from '@openchatlab/config'
 import { randomUUID } from 'crypto'
 
@@ -253,93 +252,6 @@ function loadRawConfigStore(aiDataDir: string): AIConfigStore {
 
 // ==================== PiModel Builder ====================
 
-const DEFAULT_CONTEXT_WINDOW = 128000
-
-function findModelDefinition(providerId: string, modelId: string): ModelDefinition | null {
-  const builtinForProvider = getBuiltinModelsByProvider(providerId)
-  return builtinForProvider.find((m) => m.id === modelId) || BUILTIN_MODELS.find((m) => m.id === modelId) || null
-}
-
-function normalizeAnthropicBaseUrl(url: string): string {
-  return url.replace(/\/v1\/?$/, '')
-}
-
-function normalizeOpenAICompatibleBaseUrl(url: string): string {
-  if (!url) return url
-  const trimmed = url.replace(/\/+$/, '')
-  if (trimmed.endsWith('/v1')) return trimmed
-  try {
-    const parsed = new URL(trimmed)
-    if (parsed.pathname === '/' || parsed.pathname === '') {
-      return trimmed + '/v1'
-    }
-  } catch {
-    // ignore
-  }
-  return trimmed
-}
-
 export function buildPiModel(config: AIServiceConfig): PiModel<PiApi> {
-  const providerDef = BUILTIN_PROVIDERS.find((p) => p.id === config.provider)
-  const baseUrl = config.baseUrl || providerDef?.defaultBaseUrl || ''
-  const modelId = config.model || ''
-
-  const modelDef = findModelDefinition(config.provider, modelId)
-  const contextWindow = modelDef?.contextWindow ?? DEFAULT_CONTEXT_WINDOW
-
-  const BUILTIN_PROVIDER_API: Record<string, PiApi> = {
-    gemini: 'google-generative-ai',
-    anthropic: 'anthropic-messages',
-  }
-
-  const apiFormat: PiApi = (config.apiFormat as PiApi) || BUILTIN_PROVIDER_API[config.provider] || 'openai-completions'
-
-  if (apiFormat === 'google-generative-ai') {
-    return {
-      id: modelId,
-      name: modelId,
-      api: 'google-generative-ai',
-      provider: 'google',
-      baseUrl,
-      reasoning: false,
-      input: ['text'],
-      cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
-      contextWindow,
-      maxTokens: config.maxTokens ?? 8192,
-    }
-  }
-
-  if (apiFormat === 'anthropic-messages') {
-    return {
-      id: modelId,
-      name: modelId,
-      api: 'anthropic-messages',
-      provider: 'anthropic',
-      baseUrl: normalizeAnthropicBaseUrl(baseUrl),
-      reasoning: false,
-      input: ['text'],
-      cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
-      contextWindow,
-      maxTokens: config.maxTokens ?? 8192,
-    }
-  }
-
-  const resolvedBaseUrl =
-    config.provider === 'openai-compatible' && (apiFormat === 'openai-completions' || apiFormat === 'openai-responses')
-      ? normalizeOpenAICompatibleBaseUrl(baseUrl)
-      : baseUrl
-
-  return {
-    id: modelId,
-    name: modelId,
-    api: apiFormat,
-    provider: config.provider,
-    baseUrl: resolvedBaseUrl,
-    reasoning: config.isReasoningModel ?? false,
-    input: ['text'],
-    cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0 },
-    contextWindow,
-    maxTokens: config.maxTokens ?? 4096,
-    compat: config.disableThinking ? { thinkingFormat: 'qwen' } : undefined,
-  }
+  return buildPiModelCore(config as PiModelConfig)
 }