diff --git a/src/shared/lib/ai.ts b/src/shared/lib/ai.ts
index ec88e0a..9a1b26b 100644
--- a/src/shared/lib/ai.ts
+++ b/src/shared/lib/ai.ts
@@ -1,247 +1,11 @@
-import "server-only"
-
-import { createCipheriv, createDecipheriv, createHash, randomBytes } from "node:crypto"
-import OpenAI from "openai"
-import type { ChatCompletionMessageParam } from "openai/resources/chat/completions"
-
-import { env } from "@/env.mjs"
-import { db } from "@/shared/db"
-import { aiProviders } from "@/shared/db/schema"
-import { desc, eq } from "drizzle-orm"
-
-type ChatRole = "system" | "user" | "assistant"
-
-type ChatMessage = {
-  role: ChatRole
-  content: string
-}
-
-type AiChatRequest = {
-  messages: ChatCompletionMessageParam[]
-  model: string
-  temperature: number
-  maxTokens?: number
-  thinking?: Record<string, unknown>
-  providerId?: string
-}
-
-const isRecord = (v: unknown): v is Record<string, unknown> => typeof v === "object" && v !== null
-
-const isChatMessage = (v: unknown): v is ChatMessage => {
-  if (!isRecord(v)) return false
-  const role = String(v.role ?? "")
-  if (role !== "system" && role !== "user" && role !== "assistant") return false
-  const content = String(v.content ?? "")
-  return content.trim().length > 0
-}
-
-const extractText = (value: unknown): string => {
-  if (typeof value === "string") return value.trim()
-  if (Array.isArray(value)) {
-    const joined = value.map((item) => extractText(item)).filter(Boolean).join("\n")
-    return joined.trim()
-  }
-  if (isRecord(value)) {
-    const candidates = ["text", "content", "output_text", "reasoning", "reasoning_content", "thinking"]
-    for (const key of candidates) {
-      const text = extractText(value[key])
-      if (text) return text
-    }
-  }
-  return ""
-}
-
-const extractMessageContent = (message: unknown): string => {
-  if (!isRecord(message)) return ""
-  const direct = extractText(message.content)
-  if (direct) return direct
-  const candidates = ["reasoning", "reasoning_content", "thinking", "output", "text"]
-  for (const key of candidates) {
-    const text = extractText(message[key])
-    if (text) return text
-  }
-  for (const value of Object.values(message)) {
-    const text = extractText(value)
-    if (text) return text
-  }
-  return ""
-}
-
-export const parseAiChatPayload = (body: unknown): AiChatRequest => {
-  if (!isRecord(body)) throw new Error("Invalid payload")
-
-  const rawMessages = Array.isArray(body.messages) ? body.messages : []
-  const messages = rawMessages
-    .filter(isChatMessage)
-    .map((m) => ({ role: m.role, content: m.content })) as ChatCompletionMessageParam[]
-
-  if (messages.length === 0) throw new Error("Messages are required")
-
-  const model = String(body.model ?? env.AI_MODEL ?? "gpt-4o-mini").trim()
-  const temperatureRaw = Number(body.temperature ?? 0.2)
-  const temperature = Number.isFinite(temperatureRaw) ? Math.min(Math.max(temperatureRaw, 0), 2) : 0.2
-  const maxTokensRaw = Number(body.max_tokens ?? body.maxTokens ?? 0)
-  const maxTokens = Number.isFinite(maxTokensRaw) && maxTokensRaw > 0 ? Math.floor(maxTokensRaw) : undefined
-  const thinking = isRecord(body.thinking) ? body.thinking : undefined
-  const providerId = typeof body.providerId === "string" ? body.providerId.trim() : undefined
-
-  return {
-    messages,
-    model,
-    temperature,
-    maxTokens,
-    thinking,
-    providerId: providerId && providerId.length > 0 ? providerId : undefined,
-  }
-}
-
-const getEncryptionKey = () => {
-  const secret = String(env.NEXTAUTH_SECRET ?? "").trim()
-  if (!secret) throw new Error("AI encryption secret missing")
-  return createHash("sha256").update(secret).digest()
-}
-
-export const encryptAiApiKey = (value: string) => {
-  const iv = randomBytes(12)
-  const key = getEncryptionKey()
-  const cipher = createCipheriv("aes-256-gcm", key, iv)
-  const encrypted = Buffer.concat([cipher.update(value, "utf8"), cipher.final()])
-  const tag = cipher.getAuthTag()
-  return Buffer.concat([iv, tag, encrypted]).toString("base64")
-}
-
-export const decryptAiApiKey = (value: string) => {
-  const raw = Buffer.from(value, "base64")
-  if (raw.length < 28) throw new Error("Invalid API key payload")
-  const iv = raw.subarray(0, 12)
-  const tag = raw.subarray(12, 28)
-  const encrypted = raw.subarray(28)
-  const key = getEncryptionKey()
-  const decipher = createDecipheriv("aes-256-gcm", key, iv)
-  decipher.setAuthTag(tag)
-  const decrypted = Buffer.concat([decipher.update(encrypted), decipher.final()])
-  return decrypted.toString("utf8")
-}
-
-const getAiProviderConfig = async (providerId?: string) => {
-  if (providerId) {
-    const [selected] = await db
-      .select({
-        apiKeyEncrypted: aiProviders.apiKeyEncrypted,
-        baseUrl: aiProviders.baseUrl,
-        model: aiProviders.model,
-      })
-      .from(aiProviders)
-      .where(eq(aiProviders.id, providerId))
-      .limit(1)
-    if (!selected) throw new Error("AI provider not configured")
-    return {
-      apiKey: decryptAiApiKey(selected.apiKeyEncrypted),
-      baseUrl: selected.baseUrl ?? undefined,
-      model: selected.model,
-    }
-  }
-
-  const [active] = await db
-    .select({
-      apiKeyEncrypted: aiProviders.apiKeyEncrypted,
-      baseUrl: aiProviders.baseUrl,
-      model: aiProviders.model,
-    })
-    .from(aiProviders)
-    .where(eq(aiProviders.isDefault, true))
-    .orderBy(desc(aiProviders.updatedAt))
-    .limit(1)
-  if (active) {
-    return {
-      apiKey: decryptAiApiKey(active.apiKeyEncrypted),
-      baseUrl: active.baseUrl ?? undefined,
-      model: active.model,
-    }
-  }
-
-  const [fallback] = await db
-    .select({
-      apiKeyEncrypted: aiProviders.apiKeyEncrypted,
-      baseUrl: aiProviders.baseUrl,
-      model: aiProviders.model,
-    })
-    .from(aiProviders)
-    .orderBy(desc(aiProviders.updatedAt))
-    .limit(1)
-  if (!fallback) throw new Error("AI provider not configured")
-
-  return {
-    apiKey: decryptAiApiKey(fallback.apiKeyEncrypted),
-    baseUrl: fallback.baseUrl ?? undefined,
-    model: fallback.model,
-  }
-}
-
-const getAiClient = async (config: { apiKey: string; baseUrl?: string }) => {
-  const baseUrl = String(config.baseUrl ?? "https://api.openai.com").replace(/\/+$/, "")
-  return new OpenAI({
-    apiKey: config.apiKey,
-    baseURL: baseUrl.length ? baseUrl : undefined,
-  })
-}
-
-export const testAiProviderConfig = async (input: { apiKey: string; baseUrl?: string; model: string }) => {
-  const client = await getAiClient({ apiKey: input.apiKey, baseUrl: input.baseUrl })
-  const result = await client.chat.completions.create({
-    model: input.model,
-    messages: [{ role: "user", content: "ping" }],
-    temperature: 0,
-    max_tokens: 1,
-  } as Parameters<typeof client.chat.completions.create>[0])
-  const hasChoices = "choices" in result && Array.isArray(result.choices) && result.choices.length > 0
-  if (!hasChoices) throw new Error("Empty response from provider. Check API URL, model, and API key.")
-  return true
-}
-
-export const testAiProviderById = async (
-  providerId: string,
-  overrides?: { baseUrl?: string; model?: string }
-) => {
-  const config = await getAiProviderConfig(providerId)
-  const client = await getAiClient({ apiKey: config.apiKey, baseUrl: overrides?.baseUrl ?? config.baseUrl })
-  const result = await client.chat.completions.create({
-    model: overrides?.model ?? config.model,
-    messages: [{ role: "user", content: "ping" }],
-    temperature: 0,
-    max_tokens: 1,
-  } as Parameters<typeof client.chat.completions.create>[0])
-  const hasChoices = "choices" in result && Array.isArray(result.choices) && result.choices.length > 0
-  if (!hasChoices) throw new Error("Empty response from provider. Check API URL, model, and API key.")
-  return true
-}
-
-export const createAiChatCompletion = async (input: AiChatRequest) => {
-  const config = await getAiProviderConfig(input.providerId)
-  const client = await getAiClient(config)
-  const result = (await client.chat.completions.create({
-    model: config.model || input.model,
-    messages: input.messages,
-    temperature: input.temperature,
-    ...(typeof input.maxTokens === "number" ? { max_tokens: input.maxTokens } : {}),
-    ...(input.thinking ? { thinking: input.thinking } : {}),
-  } as Parameters<typeof client.chat.completions.create>[0])) as Awaited<
-    ReturnType<typeof client.chat.completions.create>
-  >
-
-  const hasChoices = "choices" in result && Array.isArray(result.choices) && result.choices.length > 0
-  if (!hasChoices) throw new Error("Empty response from provider. Check API URL, model, and API key.")
-
-  const content = extractMessageContent(result.choices?.[0]?.message)
-  if (!content.trim()) throw new Error("Empty response content. Check model output settings.")
-
-  const usage = "usage" in result ? result.usage ?? null : null
-  return { content, usage }
-}
-
-export const getAiErrorMessage = (v: unknown) => {
-  if (v instanceof Error) return v.message
-  if (!isRecord(v)) return "AI request failed"
-  const message = String(v.message ?? "")
-  return message.trim().length ? message : "AI request failed"
-}
+// 此文件为向后兼容的重导出入口，实际实现已按职责拆分到 ./ai/ 目录：
+// - payload-parser.ts   请求负载解析
+// - api-key-crypto.ts   API Key 加密/解密
+// - provider-config.ts  Provider 配置查询
+// - client.ts           AI 客户端创建与调用
+// - errors.ts           错误格式化
+export { encryptAiApiKey, decryptAiApiKey } from "./ai/api-key-crypto"
+export { createAiChatCompletion, testAiProviderById, testAiProviderConfig } from "./ai/client"
+export { getAiErrorMessage } from "./ai/errors"
+export { parseAiChatPayload, isRecord } from "./ai/payload-parser"
+export type { AiChatRequest, ChatMessage, ChatRole } from "./ai/payload-parser"
diff --git a/src/shared/lib/ai/api-key-crypto.ts b/src/shared/lib/ai/api-key-crypto.ts
new file mode 100644
index 0000000..c5066e0
--- /dev/null
+++ b/src/shared/lib/ai/api-key-crypto.ts
@@ -0,0 +1,33 @@
+import "server-only"
+
+import { createCipheriv, createDecipheriv, createHash, randomBytes } from "node:crypto"
+
+import { env } from "@/env.mjs"
+
+const getEncryptionKey = () => {
+  const secret = String(env.NEXTAUTH_SECRET ?? "").trim()
+  if (!secret) throw new Error("AI encryption secret missing")
+  return createHash("sha256").update(secret).digest()
+}
+
+export const encryptAiApiKey = (value: string) => {
+  const iv = randomBytes(12)
+  const key = getEncryptionKey()
+  const cipher = createCipheriv("aes-256-gcm", key, iv)
+  const encrypted = Buffer.concat([cipher.update(value, "utf8"), cipher.final()])
+  const tag = cipher.getAuthTag()
+  return Buffer.concat([iv, tag, encrypted]).toString("base64")
+}
+
+export const decryptAiApiKey = (value: string) => {
+  const raw = Buffer.from(value, "base64")
+  if (raw.length < 28) throw new Error("Invalid API key payload")
+  const iv = raw.subarray(0, 12)
+  const tag = raw.subarray(12, 28)
+  const encrypted = raw.subarray(28)
+  const key = getEncryptionKey()
+  const decipher = createDecipheriv("aes-256-gcm", key, iv)
+  decipher.setAuthTag(tag)
+  const decrypted = Buffer.concat([decipher.update(encrypted), decipher.final()])
+  return decrypted.toString("utf8")
+}
diff --git a/src/shared/lib/ai/client.ts b/src/shared/lib/ai/client.ts
new file mode 100644
index 0000000..184c871
--- /dev/null
+++ b/src/shared/lib/ai/client.ts
@@ -0,0 +1,67 @@
+import "server-only"
+
+import OpenAI from "openai"
+
+import { extractMessageContent, type AiChatRequest } from "./payload-parser"
+import { getAiProviderConfig } from "./provider-config"
+
+const getAiClient = async (config: { apiKey: string; baseUrl?: string }) => {
+  const baseUrl = String(config.baseUrl ?? "https://api.openai.com").replace(/\/+$/, "")
+  return new OpenAI({
+    apiKey: config.apiKey,
+    baseURL: baseUrl.length ? baseUrl : undefined,
+  })
+}
+
+export const testAiProviderConfig = async (input: { apiKey: string; baseUrl?: string; model: string }) => {
+  const client = await getAiClient({ apiKey: input.apiKey, baseUrl: input.baseUrl })
+  const result = await client.chat.completions.create({
+    model: input.model,
+    messages: [{ role: "user", content: "ping" }],
+    temperature: 0,
+    max_tokens: 1,
+  } as Parameters<typeof client.chat.completions.create>[0])
+  const hasChoices = "choices" in result && Array.isArray(result.choices) && result.choices.length > 0
+  if (!hasChoices) throw new Error("Empty response from provider. Check API URL, model, and API key.")
+  return true
+}
+
+export const testAiProviderById = async (
+  providerId: string,
+  overrides?: { baseUrl?: string; model?: string }
+) => {
+  const config = await getAiProviderConfig(providerId)
+  const client = await getAiClient({ apiKey: config.apiKey, baseUrl: overrides?.baseUrl ?? config.baseUrl })
+  const result = await client.chat.completions.create({
+    model: overrides?.model ?? config.model,
+    messages: [{ role: "user", content: "ping" }],
+    temperature: 0,
+    max_tokens: 1,
+  } as Parameters<typeof client.chat.completions.create>[0])
+  const hasChoices = "choices" in result && Array.isArray(result.choices) && result.choices.length > 0
+  if (!hasChoices) throw new Error("Empty response from provider. Check API URL, model, and API key.")
+  return true
+}
+
+export const createAiChatCompletion = async (input: AiChatRequest) => {
+  const config = await getAiProviderConfig(input.providerId)
+  const client = await getAiClient(config)
+  const result = (await client.chat.completions.create({
+    model: config.model || input.model,
+    messages: input.messages,
+    temperature: input.temperature,
+    ...(typeof input.maxTokens === "number" ? { max_tokens: input.maxTokens } : {}),
+    ...(input.thinking ? { thinking: input.thinking } : {}),
+  } as Parameters<typeof client.chat.completions.create>[0])) as Awaited<
+    ReturnType<typeof client.chat.completions.create>
+  >
+
+  const hasChoices = "choices" in result && Array.isArray(result.choices) && result.choices.length > 0
+  if (!hasChoices) throw new Error("Empty response from provider. Check API URL, model, and API key.")
+
+  const content = extractMessageContent(result.choices?.[0]?.message)
+  if (!content.trim()) throw new Error("Empty response content. Check model output settings.")
+
+  const usage = "usage" in result ? result.usage ?? null : null
+  return { content, usage }
+}
diff --git a/src/shared/lib/ai/errors.ts b/src/shared/lib/ai/errors.ts
new file mode 100644
index 0000000..e9f0633
--- /dev/null
+++ b/src/shared/lib/ai/errors.ts
@@ -0,0 +1,10 @@
+import "server-only"
+
+import { isRecord } from "./payload-parser"
+
+export const getAiErrorMessage = (v: unknown) => {
+  if (v instanceof Error) return v.message
+  if (!isRecord(v)) return "AI request failed"
+  const message = String(v.message ?? "")
+  return message.trim().length ? message : "AI request failed"
+}
diff --git a/src/shared/lib/ai/index.ts b/src/shared/lib/ai/index.ts
new file mode 100644
index 0000000..8acd4e7
--- /dev/null
+++ b/src/shared/lib/ai/index.ts
@@ -0,0 +1,5 @@
+export { encryptAiApiKey, decryptAiApiKey } from "./api-key-crypto"
+export { createAiChatCompletion, testAiProviderById, testAiProviderConfig } from "./client"
+export { getAiErrorMessage } from "./errors"
+export { parseAiChatPayload, isRecord } from "./payload-parser"
+export type { AiChatRequest, ChatMessage, ChatRole } from "./payload-parser"
diff --git a/src/shared/lib/ai/payload-parser.ts b/src/shared/lib/ai/payload-parser.ts
new file mode 100644
index 0000000..1027bc0
--- /dev/null
+++ b/src/shared/lib/ai/payload-parser.ts
@@ -0,0 +1,93 @@
+import "server-only"
+
+import type { ChatCompletionMessageParam } from "openai/resources/chat/completions"
+
+import { env } from "@/env.mjs"
+
+export type ChatRole = "system" | "user" | "assistant"
+
+export type ChatMessage = {
+  role: ChatRole
+  content: string
+}
+
+export type AiChatRequest = {
+  messages: ChatCompletionMessageParam[]
+  model: string
+  temperature: number
+  maxTokens?: number
+  thinking?: Record<string, unknown>
+  providerId?: string
+}
+
+export const isRecord = (v: unknown): v is Record<string, unknown> => typeof v === "object" && v !== null
+
+const isChatMessage = (v: unknown): v is ChatMessage => {
+  if (!isRecord(v)) return false
+  const role = String(v.role ?? "")
+  if (role !== "system" && role !== "user" && role !== "assistant") return false
+  const content = String(v.content ?? "")
+  return content.trim().length > 0
+}
+
+const extractText = (value: unknown): string => {
+  if (typeof value === "string") return value.trim()
+  if (Array.isArray(value)) {
+    const joined = value.map((item) => extractText(item)).filter(Boolean).join("\n")
+    return joined.trim()
+  }
+  if (isRecord(value)) {
+    const candidates = ["text", "content", "output_text", "reasoning", "reasoning_content", "thinking"]
+    for (const key of candidates) {
+      const text = extractText(value[key])
+      if (text) return text
+    }
+  }
+  return ""
+}
+
+const extractMessageContent = (message: unknown): string => {
+  if (!isRecord(message)) return ""
+  const direct = extractText(message.content)
+  if (direct) return direct
+  const candidates = ["reasoning", "reasoning_content", "thinking", "output", "text"]
+  for (const key of candidates) {
+    const text = extractText(message[key])
+    if (text) return text
+  }
+  for (const value of Object.values(message)) {
+    const text = extractText(value)
+    if (text) return text
+  }
+  return ""
+}
+
+export const parseAiChatPayload = (body: unknown): AiChatRequest => {
+  if (!isRecord(body)) throw new Error("Invalid payload")
+
+  const rawMessages = Array.isArray(body.messages) ? body.messages : []
+  const messages = rawMessages
+    .filter(isChatMessage)
+    .map((m) => ({ role: m.role, content: m.content })) as ChatCompletionMessageParam[]
+
+  if (messages.length === 0) throw new Error("Messages are required")
+
+  const model = String(body.model ?? env.AI_MODEL ?? "gpt-4o-mini").trim()
+  const temperatureRaw = Number(body.temperature ?? 0.2)
+  const temperature = Number.isFinite(temperatureRaw) ? Math.min(Math.max(temperatureRaw, 0), 2) : 0.2
+  const maxTokensRaw = Number(body.max_tokens ?? body.maxTokens ?? 0)
+  const maxTokens = Number.isFinite(maxTokensRaw) && maxTokensRaw > 0 ? Math.floor(maxTokensRaw) : undefined
+  const thinking = isRecord(body.thinking) ? body.thinking : undefined
+  const providerId = typeof body.providerId === "string" ? body.providerId.trim() : undefined
+
+  return {
+    messages,
+    model,
+    temperature,
+    maxTokens,
+    thinking,
+    providerId: providerId && providerId.length > 0 ? providerId : undefined,
+  }
+}
+
+export { extractMessageContent }
diff --git a/src/shared/lib/ai/provider-config.ts b/src/shared/lib/ai/provider-config.ts
new file mode 100644
index 0000000..16192f7
--- /dev/null
+++ b/src/shared/lib/ai/provider-config.ts
@@ -0,0 +1,69 @@
+import "server-only"
+
+import { desc, eq } from "drizzle-orm"
+
+import { db } from "@/shared/db"
+import { aiProviders } from "@/shared/db/schema"
+
+import { decryptAiApiKey } from "./api-key-crypto"
+
+export type AiProviderConfig = {
+  apiKey: string
+  baseUrl?: string
+  model: string
+}
+
+export const getAiProviderConfig = async (providerId?: string): Promise<AiProviderConfig> => {
+  if (providerId) {
+    const [selected] = await db
+      .select({
+        apiKeyEncrypted: aiProviders.apiKeyEncrypted,
+        baseUrl: aiProviders.baseUrl,
+        model: aiProviders.model,
+      })
+      .from(aiProviders)
+      .where(eq(aiProviders.id, providerId))
+      .limit(1)
+    if (!selected) throw new Error("AI provider not configured")
+    return {
+      apiKey: decryptAiApiKey(selected.apiKeyEncrypted),
+      baseUrl: selected.baseUrl ?? undefined,
+      model: selected.model,
+    }
+  }
+
+  const [active] = await db
+    .select({
+      apiKeyEncrypted: aiProviders.apiKeyEncrypted,
+      baseUrl: aiProviders.baseUrl,
+      model: aiProviders.model,
+    })
+    .from(aiProviders)
+    .where(eq(aiProviders.isDefault, true))
+    .orderBy(desc(aiProviders.updatedAt))
+    .limit(1)
+  if (active) {
+    return {
+      apiKey: decryptAiApiKey(active.apiKeyEncrypted),
+      baseUrl: active.baseUrl ?? undefined,
+      model: active.model,
+    }
+  }
+
+  const [fallback] = await db
+    .select({
+      apiKeyEncrypted: aiProviders.apiKeyEncrypted,
+      baseUrl: aiProviders.baseUrl,
+      model: aiProviders.model,
+    })
+    .from(aiProviders)
+    .orderBy(desc(aiProviders.updatedAt))
+    .limit(1)
+  if (!fallback) throw new Error("AI provider not configured")
+
+  return {
+    apiKey: decryptAiApiKey(fallback.apiKeyEncrypted),
+    baseUrl: fallback.baseUrl ?? undefined,
+    model: fallback.model,
+  }
+}