refactor: 清理 AI 客户端死代码并统一错误处理

- 删除未使用的 OpenAiCompatibleClient，DTO 抽离到 ai_contracts.cs
- 新增 AiHttpResponseGuard 统一 LLM/VLM 的 HTTP 错误处理：
  错误响应带响应体（截断 2000 字符）、空响应与无效 JSON 显式抛 InvalidDataException
- 空 catch 补全精确异常类型（IOException/UnauthorizedAccessException/JsonException）
- 修正 Program.cs 数据库初始化注释
- 新增 AI 客户端错误处理单元测试

backend/src/Health.Infrastructure/AI/ai_clients.cs

@@ -40,7 +40,7 @@ public sealed class DeepSeekClient(HttpClient http, IConfiguration config)
         httpRequest.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("text/event-stream"));
 
         using var response = await _http.SendAsync(httpRequest, HttpCompletionOption.ResponseHeadersRead, ct);
-        response.EnsureSuccessStatusCode();
+        await AiHttpResponseGuard.ThrowIfFailedAsync(response, "DeepSeek", ct);
 
         using var stream = await response.Content.ReadAsStreamAsync(ct);
         using var reader = new StreamReader(stream);
@@ -76,11 +76,9 @@ public sealed class DeepSeekClient(HttpClient http, IConfiguration config)
         var json = JsonSerializer.Serialize(request, _jsonOptions);
         var content = new StringContent(json, Encoding.UTF8, "application/json");
 
-        var response = await _http.PostAsync("chat/completions", content, ct);
-        response.EnsureSuccessStatusCode();
-
-        var body = await response.Content.ReadAsStringAsync(ct);
-        return JsonSerializer.Deserialize<ChatCompletionResponse>(body, _jsonOptions)!;
+        using var response = await _http.PostAsync("chat/completions", content, ct);
+        var body = await AiHttpResponseGuard.ReadSuccessBodyAsync(response, "DeepSeek", ct);
+        return AiHttpResponseGuard.DeserializeRequired<ChatCompletionResponse>(body, _jsonOptions, "DeepSeek");
     }
 }
 
@@ -125,13 +123,45 @@ public sealed class VisionClient(HttpClient http, IConfiguration config)
 
         var json = JsonSerializer.Serialize(request, _jsonOptions);
         var content = new StringContent(json, Encoding.UTF8, "application/json");
-        var response = await _http.PostAsync("chat/completions", content, ct);
-        if (!response.IsSuccessStatusCode)
-        {
-            var errorBody = await response.Content.ReadAsStringAsync(ct);
-            throw new HttpRequestException($"VLM API {response.StatusCode}: {errorBody}");
-        }
-        var body = await response.Content.ReadAsStringAsync(ct);
-        return JsonSerializer.Deserialize<ChatCompletionResponse>(body, _jsonOptions)!;
+        using var response = await _http.PostAsync("chat/completions", content, ct);
+        var body = await AiHttpResponseGuard.ReadSuccessBodyAsync(response, "VLM", ct);
+        return AiHttpResponseGuard.DeserializeRequired<ChatCompletionResponse>(body, _jsonOptions, "VLM");
     }
 }
+
+internal static class AiHttpResponseGuard
+{
+    private const int MaxErrorBodyLength = 2000;
+
+    public static async Task ThrowIfFailedAsync(HttpResponseMessage response, string provider, CancellationToken ct)
+    {
+        if (response.IsSuccessStatusCode) return;
+        var body = await response.Content.ReadAsStringAsync(ct);
+        throw new HttpRequestException($"{provider} API {(int)response.StatusCode} ({response.StatusCode}): {Truncate(body)}");
+    }
+
+    public static async Task<string> ReadSuccessBodyAsync(HttpResponseMessage response, string provider, CancellationToken ct)
+    {
+        await ThrowIfFailedAsync(response, provider, ct);
+        var body = await response.Content.ReadAsStringAsync(ct);
+        if (string.IsNullOrWhiteSpace(body))
+            throw new InvalidDataException($"{provider} API返回了空响应");
+        return body;
+    }
+
+    public static T DeserializeRequired<T>(string body, JsonSerializerOptions options, string provider)
+    {
+        try
+        {
+            return JsonSerializer.Deserialize<T>(body, options)
+                ?? throw new InvalidDataException($"{provider} API响应内容为空");
+        }
+        catch (JsonException ex)
+        {
+            throw new InvalidDataException($"{provider} API响应格式无效", ex);
+        }
+    }
+
+    private static string Truncate(string value) =>
+        value.Length <= MaxErrorBodyLength ? value : value[..MaxErrorBodyLength] + "...";
+}

backend/src/Health.Infrastructure/AI/ai_contracts.cs

@@ -0,0 +1,81 @@
+namespace Health.Infrastructure.AI;
+
+public sealed class ChatCompletionRequest
+{
+    public string Model { get; set; } = string.Empty;
+    public List<ChatMessage> Messages { get; set; } = [];
+    public bool Stream { get; set; }
+    public int MaxTokens { get; set; } = 2048;
+    public float Temperature { get; set; } = 0.7f;
+    public float? TopP { get; set; }
+    public List<ToolDefinition>? Tools { get; set; }
+    public string? ToolChoice { get; set; }
+
+    [System.Text.Json.Serialization.JsonPropertyName("vl_high_resolution_images")]
+    public bool VlHighResolutionImages { get; set; }
+}
+
+public sealed class ChatMessage
+{
+    public string Role { get; set; } = string.Empty;
+    public object? Content { get; set; } = string.Empty;
+
+    [System.Text.Json.Serialization.JsonIgnore(Condition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull)]
+    public string? ToolCallId { get; set; }
+
+    [System.Text.Json.Serialization.JsonIgnore(Condition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull)]
+    public List<ToolCall>? ToolCalls { get; set; }
+}
+
+public sealed class ToolDefinition
+{
+    public string Type { get; set; } = "function";
+    public ToolFunction Function { get; set; } = new();
+}
+
+public sealed class ToolFunction
+{
+    public string Name { get; set; } = string.Empty;
+    public string Description { get; set; } = string.Empty;
+    public object Parameters { get; set; } = new();
+}
+
+public sealed class ToolCall
+{
+    public string Id { get; set; } = string.Empty;
+    public string Type { get; set; } = "function";
+    public ToolCallFunction Function { get; set; } = new();
+}
+
+public sealed class ToolCallFunction
+{
+    public string Name { get; set; } = string.Empty;
+    public string Arguments { get; set; } = string.Empty;
+}
+
+public sealed class ChatCompletionResponse
+{
+    public string Id { get; set; } = string.Empty;
+    public List<Choice> Choices { get; set; } = [];
+}
+
+public sealed class Choice
+{
+    public int Index { get; set; }
+    public ResponseMessage? Message { get; set; }
+    public ResponseDelta? Delta { get; set; }
+    public string? FinishReason { get; set; }
+}
+
+public sealed class ResponseMessage
+{
+    public string Role { get; set; } = string.Empty;
+    public string? Content { get; set; }
+    public List<ToolCall>? ToolCalls { get; set; }
+}
+
+public sealed class ResponseDelta
+{
+    public string? Content { get; set; }
+    public string? Role { get; set; }
+}

backend/src/Health.Infrastructure/AI/open_ai_compatible_client.cs

@@ -1,237 +0,0 @@
-using System.Net.Http.Headers;
-
-namespace Health.Infrastructure.AI;
-
-/// <summary>
-/// OpenAI 兼容协议 HTTP 客户端，统一调用 DeepSeek / 千问 VL
-/// </summary>
-public sealed class OpenAiCompatibleClient(string baseUrl, string apiKey, string model)
-{
-    private readonly HttpClient _http = CreateHttpClient(baseUrl, apiKey);
-    private readonly string _model = model;
-    private readonly JsonSerializerOptions _jsonOptions = new()
-    {
-        PropertyNamingPolicy = JsonNamingPolicy.SnakeCaseLower,
-        PropertyNameCaseInsensitive = true
-    };
-
-    private static HttpClient CreateHttpClient(string baseUrl, string apiKey)
-    {
-        var client = new HttpClient
-        {
-            BaseAddress = new Uri(baseUrl.TrimEnd('/') + "/"),
-            Timeout = TimeSpan.FromSeconds(60)
-        };
-        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", apiKey);
-        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
-        return client;
-    }
-
-    /// <summary>
-    /// 流式 Chat Completions（SSE）
-    /// </summary>
-    public async IAsyncEnumerable<string> ChatStreamAsync(
-        List<ChatMessage> messages,
-        List<ToolDefinition>? tools = null,
-        int maxTokens = 2048,
-        float temperature = 0.7f)
-    {
-        var request = new ChatCompletionRequest
-        {
-            Model = _model,
-            Messages = messages,
-            Stream = true,
-            MaxTokens = maxTokens,
-            Temperature = temperature,
-            Tools = tools,
-        };
-
-        if (tools?.Count > 0)
-            request.ToolChoice = "auto";
-
-        var json = JsonSerializer.Serialize(request, _jsonOptions);
-        var content = new StringContent(json, Encoding.UTF8, "application/json");
-
-        var httpRequest = new HttpRequestMessage(HttpMethod.Post, "chat/completions")
-        {
-            Content = content
-        };
-        httpRequest.Headers.Accept.Add(new MediaTypeWithQualityHeaderValue("text/event-stream"));
-
-        var response = await _http.SendAsync(httpRequest, HttpCompletionOption.ResponseHeadersRead);
-        response.EnsureSuccessStatusCode();
-
-        using var stream = await response.Content.ReadAsStreamAsync();
-        using var reader = new StreamReader(stream);
-
-        string? line;
-        while ((line = await reader.ReadLineAsync()) != null)
-        {
-            if (string.IsNullOrWhiteSpace(line)) continue;
-            if (!line.StartsWith("data: ")) continue;
-
-            var data = line["data: ".Length..];
-            if (data == "[DONE]") break;
-
-            yield return data;
-        }
-    }
-
-    /// <summary>
-    /// 非流式 Chat Completions
-    /// </summary>
-    public async Task<ChatCompletionResponse> ChatAsync(
-        List<ChatMessage> messages,
-        List<ToolDefinition>? tools = null,
-        int maxTokens = 2048,
-        float temperature = 0.7f)
-    {
-        var request = new ChatCompletionRequest
-        {
-            Model = _model,
-            Messages = messages,
-            Stream = false,
-            MaxTokens = maxTokens,
-            Temperature = temperature,
-            Tools = tools,
-        };
-
-        if (tools?.Count > 0)
-            request.ToolChoice = "auto";
-
-        var json = JsonSerializer.Serialize(request, _jsonOptions);
-        var content = new StringContent(json, Encoding.UTF8, "application/json");
-
-        var response = await _http.PostAsync("chat/completions", content);
-        response.EnsureSuccessStatusCode();
-
-        var body = await response.Content.ReadAsStringAsync();
-        return JsonSerializer.Deserialize<ChatCompletionResponse>(body, _jsonOptions)!;
-    }
-
-    /// <summary>
-    /// Vision 图片理解（非流式）
-    /// </summary>
-    public async Task<ChatCompletionResponse> VisionAsync(
-        string systemPrompt,
-        List<string> imageUrls,
-        string? userText = null,
-        int maxTokens = 2048)
-    {
-        var messages = new List<ChatMessage>();
-
-        if (!string.IsNullOrEmpty(systemPrompt))
-            messages.Add(new ChatMessage { Role = "system", Content = systemPrompt });
-
-        // 构建多模态消息内容
-        var contentParts = new List<object>();
-        foreach (var url in imageUrls)
-            contentParts.Add(new { type = "image_url", image_url = new { url } });
-        if (!string.IsNullOrEmpty(userText))
-            contentParts.Add(new { type = "text", text = userText });
-
-        var userMessage = new ChatMessage
-        {
-            Role = "user",
-            Content = contentParts  // 数组格式，让 JSON 序列化时保持为数组而非字符串
-        };
-
-        messages.Add(userMessage);
-
-        var request = new ChatCompletionRequest
-        {
-            Model = _model,
-            Messages = messages,
-            MaxTokens = maxTokens,
-            Stream = false,
-        };
-
-        var json = JsonSerializer.Serialize(request, _jsonOptions);
-        var content = new StringContent(json, Encoding.UTF8, "application/json");
-        var response = await _http.PostAsync("chat/completions", content);
-        response.EnsureSuccessStatusCode();
-        var body = await response.Content.ReadAsStringAsync();
-        return JsonSerializer.Deserialize<ChatCompletionResponse>(body, _jsonOptions)!;
-    }
-}
-
-#region 请求/响应模型
-
-public sealed class ChatCompletionRequest
-{
-    public string Model { get; set; } = string.Empty;
-    public List<ChatMessage> Messages { get; set; } = [];
-    public bool Stream { get; set; }
-    public int MaxTokens { get; set; } = 2048;
-    public float Temperature { get; set; } = 0.7f;
-    public float? TopP { get; set; }
-    public List<ToolDefinition>? Tools { get; set; }
-    public string? ToolChoice { get; set; }
-    [System.Text.Json.Serialization.JsonPropertyName("vl_high_resolution_images")]
-    public bool VlHighResolutionImages { get; set; }
-}
-
-public sealed class ChatMessage
-{
-    public string Role { get; set; } = string.Empty;
-    public object? Content { get; set; } = string.Empty;
-    [System.Text.Json.Serialization.JsonIgnore(Condition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull)]
-    public string? ToolCallId { get; set; }
-    [System.Text.Json.Serialization.JsonIgnore(Condition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull)]
-    public List<ToolCall>? ToolCalls { get; set; }
-}
-
-public sealed class ToolDefinition
-{
-    public string Type { get; set; } = "function";
-    public ToolFunction Function { get; set; } = new();
-}
-
-public sealed class ToolFunction
-{
-    public string Name { get; set; } = string.Empty;
-    public string Description { get; set; } = string.Empty;
-    public object Parameters { get; set; } = new();
-}
-
-public sealed class ToolCall
-{
-    public string Id { get; set; } = string.Empty;
-    public string Type { get; set; } = "function";
-    public ToolCallFunction Function { get; set; } = new();
-}
-
-public sealed class ToolCallFunction
-{
-    public string Name { get; set; } = string.Empty;
-    public string Arguments { get; set; } = string.Empty;
-}
-
-public sealed class ChatCompletionResponse
-{
-    public string Id { get; set; } = string.Empty;
-    public List<Choice> Choices { get; set; } = [];
-}
-
-public sealed class Choice
-{
-    public int Index { get; set; }
-    public ResponseMessage? Message { get; set; }
-    public ResponseDelta? Delta { get; set; }
-    public string? FinishReason { get; set; }
-}
-
-public sealed class ResponseMessage
-{
-    public string Role { get; set; } = string.Empty;
-    public string? Content { get; set; }
-    public List<ToolCall>? ToolCalls { get; set; }
-}
-
-public sealed class ResponseDelta
-{
-    public string? Content { get; set; }
-    public string? Role { get; set; }
-}
-
-#endregion

backend/src/Health.Infrastructure/Diets/DietImageAnalysisCoordinator.cs

@@ -50,7 +50,8 @@ public sealed class DietImageAnalysisCoordinator(IDietImageAnalysisQueue queue)
                 foreach (var path in paths)
                 {
                     try { if (File.Exists(path)) File.Delete(path); }
-                    catch { }
+                    catch (IOException) { }
+                    catch (UnauthorizedAccessException) { }
                 }
             }
             throw;

backend/src/Health.Infrastructure/Reports/ReportAnalysisService.cs

@@ -160,6 +160,6 @@ public sealed class ReportAnalysisService(
 
         content = content.Trim();
         try { return JsonDocument.Parse(content).RootElement; }
-        catch { return null; }
+        catch (JsonException) { return null; }
     }
 }

backend/src/Health.WebApi/BackgroundServices/diet_image_analysis_worker.cs

@@ -67,7 +67,8 @@ public sealed class DietImageAnalysisWorker(
         foreach (var path in paths)
         {
             try { if (File.Exists(path)) File.Delete(path); }
-            catch { }
+            catch (IOException) { }
+            catch (UnauthorizedAccessException) { }
         }
     }
 }

backend/src/Health.WebApi/Endpoints/ai_chat_endpoints.cs

@@ -521,7 +521,7 @@ public static class AiChatEndpoints
                 var json = JsonSerializer.Serialize(toolResult, JsonOpts);
                 resultDict = JsonSerializer.Deserialize<Dictionary<string, object>>(json, JsonOpts);
             }
-            catch { resultDict = new Dictionary<string, object>(); }
+            catch (JsonException) { resultDict = new Dictionary<string, object>(); }
         }
 
         var isPendingConfirmation = resultDict != null

backend/src/Health.WebApi/Program.cs

@@ -202,7 +202,7 @@ app.UseStaticFiles(new StaticFileOptions
 if (app.Environment.IsDevelopment())
     app.MapOpenApi();
 
-// ---- 初始化数据库（开发环境：每次重建）----
+// ---- 初始化数据库：创建空库，并用版本化补丁更新已有本地结构 ----
 using (var scope = app.Services.CreateScope())
 {
     var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();

backend/tests/Health.Tests/ai_client_error_tests.cs

@@ -0,0 +1,50 @@
+using System.Net;
+using Health.Infrastructure.AI;
+using Microsoft.Extensions.Configuration;
+
+namespace Health.Tests;
+
+public sealed class AiClientErrorTests
+{
+    [Fact]
+    public async Task DeepSeek_ErrorResponse_IncludesStatusAndBody()
+    {
+        var client = CreateClient(HttpStatusCode.TooManyRequests, "{\"error\":\"rate limit\"}");
+
+        var error = await Assert.ThrowsAsync<HttpRequestException>(() => client.ChatAsync([]));
+
+        Assert.Contains("429", error.Message);
+        Assert.Contains("rate limit", error.Message);
+    }
+
+    [Fact]
+    public async Task DeepSeek_NullJsonResponse_ThrowsClearDataError()
+    {
+        var client = CreateClient(HttpStatusCode.OK, "null");
+
+        var error = await Assert.ThrowsAsync<InvalidDataException>(() => client.ChatAsync([]));
+
+        Assert.Contains("响应内容为空", error.Message);
+    }
+
+    private static DeepSeekClient CreateClient(HttpStatusCode statusCode, string body)
+    {
+        var http = new HttpClient(new StubHandler(statusCode, body))
+        {
+            BaseAddress = new Uri("https://example.test/"),
+        };
+        var config = new ConfigurationBuilder().AddInMemoryCollection(
+            new Dictionary<string, string?> { ["DEEPSEEK_MODEL"] = "test-model" }).Build();
+        return new DeepSeekClient(http, config);
+    }
+
+    private sealed class StubHandler(HttpStatusCode statusCode, string body) : HttpMessageHandler
+    {
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken) =>
+            Task.FromResult(new HttpResponseMessage(statusCode)
+            {
+                Content = new StringContent(body),
+                RequestMessage = request,
+            });
+    }
+}