refactor: reorganize providers into directory, add tests and error types

- Move provider.cppm, openai.cppm, anthropic.cppm into src/providers/
- Add ApiError and ConnectionError in src/errors.cppm
- Add live API tests (OpenAI, Anthropic), tool calling, structured output, embeddings tests
- Add integration test verifying concepts and type system
- Update examples to new Client<Provider> API
- Clean up xmake.lua (global c++23/modules policy)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: Sunrisepeak

examples/basic.cpp

@@ -1,68 +1,51 @@
 // Basic usage example - demonstrates both streaming and non-streaming modes
-import std;
 import mcpplibs.llmapi;
+import std;
 
-using namespace mcpplibs;
+using namespace mcpplibs::llmapi;
 
 int main() {
-    auto api_key = std::getenv("OPENAI_API_KEY");
-    if (!api_key) {
+    auto apiKey = std::getenv("OPENAI_API_KEY");
+    if (!apiKey) {
         std::println("Error: OPENAI_API_KEY not set");
         return 1;
     }
 
-    llmapi::Client client(api_key, llmapi::URL::Poe);
-    client.model("gpt-5").system("You are a helpful assistant.");
+    auto client = Client(openai::OpenAI({
+        .apiKey = apiKey,
+        .model = "gpt-4o-mini",
+    }));
+    client.system("You are a helpful assistant.");
 
     std::println("=== llmapi Basic Usage Demo ===\n");
 
     try {
         // Example 1: Non-streaming request
         std::println("[Example 1] Non-streaming mode:");
         std::println("Question: What is the capital of China?\n");
-        
-        client.user("What is the capital of China?");
-        client.request();
-        
-        std::println("Answer: {}\n", client.getAnswer());
+
+        auto resp = client.chat("What is the capital of China?");
+        std::println("Answer: {}\n", resp.text());
 
         // Example 2: Streaming request
         std::println("[Example 2] Streaming mode:");
         std::println("Question: Convince me to use modern C++ (100 words)\n");
 
-        client.user("Convince me to use modern C++ (100 words)");
+        client.clear();
+        client.system("You are a helpful assistant.");
         std::print("Answer: ");
-
-        client.request([](std::string_view chunk) {
-            std::print("{}", chunk);
-            std::cout.flush();
-        });
-        
+        auto resp2 = client.chat_stream("Convince me to use modern C++ (100 words)",
+            [](std::string_view chunk) {
+                std::print("{}", chunk);
+            });
         std::println("\n");
+        std::println("[Verification] Answer length: {} chars\n", resp2.text().size());
 
-        // Verify auto-save: get the last answer
-        auto last_answer = client.getAnswer();
-        std::println("[Verification] Last answer length: {} chars\n", last_answer.size());
-
-        // Example 3: Translate the story to Chinese
-        std::println("[Example 3] Translation (streaming):");
-        std::println("Question: 请把上个回答翻译成中文。\n");
-        
-        client.user("请把上面的故事翻译成中文。");
-        std::print("Answer: ");
-        
-        client.request([](std::string_view chunk) {
-            std::print("{}", chunk);
-            std::cout.flush();
-        });
-        
-        std::println("\n");
-        
     } catch (const std::exception& e) {
         std::println("\nError: {}\n", e.what());
         return 1;
     }
 
     std::println("=== Demo Complete ===");
     return 0;
-}
+}

examples/chat.cpp

@@ -1,18 +1,21 @@
 // Simple and elegant AI chat CLI tool using streaming
-import std;
 import mcpplibs.llmapi;
+import std;
 
-using namespace mcpplibs;
+using namespace mcpplibs::llmapi;
 
 int main() {
-    auto api_key = std::getenv("OPENAI_API_KEY");
-    if (!api_key) {
+    auto apiKey = std::getenv("OPENAI_API_KEY");
+    if (!apiKey) {
         std::println("Error: OPENAI_API_KEY not set");
         return 1;
     }
 
-    llmapi::Client client(api_key, llmapi::URL::Poe);
-    client.model("gpt-5").system("You are a helpful assistant.");
+    auto client = Client(openai::OpenAI({
+        .apiKey = apiKey,
+        .model = "gpt-4o-mini",
+    }));
+    client.system("You are a helpful assistant.");
 
     std::println("AI Chat CLI - Type 'quit' to exit\n");
 
@@ -29,20 +32,16 @@ int main() {
         if (input.empty()) continue;
 
         try {
-            client.user(input);
             std::print("\nAI: ");
-            
-            client.request([](std::string_view chunk) {
+            client.chat_stream(input, [](std::string_view chunk) {
                 std::print("{}", chunk);
-                std::cout.flush();
             });
-            
             std::println("\n");
-            
+
         } catch (const std::exception& e) {
             std::println("\nError: {}\n", e.what());
         }
     }
 
     return 0;
-}
+}

examples/hello_mcpp.cpp

@@ -1,19 +1,23 @@
 // Minimal example - simplest way to use llmapi
-import std;
 import mcpplibs.llmapi;
+import std;
+
+using namespace mcpplibs::llmapi;
 
 int main() {
-    using namespace mcpplibs;
-    
-    llmapi::Client client(std::getenv("OPENAI_API_KEY"), llmapi::URL::Poe);
+    auto apiKey = std::getenv("OPENAI_API_KEY");
+    if (!apiKey) {
+        std::println("Error: OPENAI_API_KEY not set");
+        return 1;
+    }
+
+    auto client = Client(openai::OpenAI({
+        .apiKey = apiKey,
+        .model = "gpt-4o-mini",
+    }));
 
-    client.model("gpt-5")
-          .system("You are a helpful assistant.")
-          .user("In one sentence, introduce modern C++. 并给出中文翻译")
-          .request([](std::string_view chunk) {
-                std::print("{}", chunk);
-                std::cout.flush();
-          });
+    auto resp = client.chat("Hello! In one sentence, introduce modern C++.");
+    std::println("{}", resp.text());
 
     return 0;
-}
+}

src/errors.cppm

@@ -0,0 +1,28 @@
+export module mcpplibs.llmapi:errors;
+
+import std;
+
+export namespace mcpplibs::llmapi {
+
+// Base API error with HTTP status and structured error info
+class ApiError : public std::runtime_error {
+public:
+    int statusCode;
+    std::string type;
+    std::string body;
+
+    ApiError(int status, std::string errorType, std::string errorBody, const std::string& message)
+        : std::runtime_error(message)
+        , statusCode(status)
+        , type(std::move(errorType))
+        , body(std::move(errorBody))
+    {}
+};
+
+// Network/connection errors (DNS, TLS, timeout)
+class ConnectionError : public std::runtime_error {
+public:
+    using std::runtime_error::runtime_error;
+};
+
+} // namespace mcpplibs::llmapi

src/llmapi.cppm

@@ -7,6 +7,7 @@ export import :provider;
 export import :client;
 export import :openai;
 export import :anthropic;
+export import :errors;
 
 import std;
 

src/anthropic.cppm src/providers/anthropic.cppmsrc/anthropic.cppm renamed to src/providers/anthropic.cppm

@@ -0,0 +1,44 @@
+import mcpplibs.llmapi;
+import std;
+
+#include <cassert>
+
+using namespace mcpplibs::llmapi;
+
+int main() {
+    auto apiKey = std::getenv("ANTHROPIC_API_KEY");
+    if (!apiKey) {
+        std::println("ANTHROPIC_API_KEY not set, skipping live test");
+        return 0;
+    }
+
+    auto client = Client(anthropic::Anthropic({
+        .apiKey = apiKey,
+        .model = "claude-haiku-4-5-20251001",
+    }));
+
+    // Test 1: basic chat
+    auto resp = client.chat("Say exactly: HELLO_TEST_OK");
+    std::println("Response: {}", resp.text());
+    assert(!resp.text().empty());
+    assert(resp.usage.inputTokens > 0);
+
+    // Test 2: system message
+    client.clear();
+    client.system("Always respond with exactly one word.");
+    auto resp2 = client.chat("What color is the sky?");
+    std::println("System test: {}", resp2.text());
+
+    // Test 3: streaming
+    client.clear();
+    std::string streamed;
+    auto resp3 = client.chat_stream("Say exactly: STREAM_OK", [&](std::string_view chunk) {
+        streamed += chunk;
+        std::print("{}", chunk);
+    });
+    std::println("");
+    assert(!streamed.empty());
+
+    std::println("test_anthropic_live: ALL PASSED");
+    return 0;
+}

src/openai.cppm src/providers/openai.cppmsrc/openai.cppm renamed to src/providers/openai.cppm

@@ -0,0 +1,32 @@
+import mcpplibs.llmapi;
+import std;
+
+#include <cassert>
+
+using namespace mcpplibs::llmapi;
+
+int main() {
+    auto apiKey = std::getenv("OPENAI_API_KEY");
+    if (!apiKey) {
+        std::println("OPENAI_API_KEY not set, skipping");
+        return 0;
+    }
+
+    auto provider = openai::OpenAI({
+        .apiKey = apiKey,
+        .model = "gpt-4o-mini",
+    });
+
+    auto resp = provider.embed(
+        {"Hello world", "How are you"},
+        "text-embedding-3-small"
+    );
+
+    assert(resp.embeddings.size() == 2);
+    assert(!resp.embeddings[0].empty());
+    assert(resp.usage.inputTokens > 0);
+    std::println("Embedding dim: {}", resp.embeddings[0].size());
+
+    std::println("test_embeddings: ALL PASSED");
+    return 0;
+}