diff --git a/README.md b/README.md
index 940070f..ac2e7bc 100644
--- a/README.md
+++ b/README.md
@@ -17,7 +17,7 @@ to it)
 *   **`Client Layer`**: 
     *   `OllamaClient`: Handles the actual communication with an Ollama-compatible API server via HTTP (using `libcurl`).
     *   `DebugClient`: A CLI-friendly mock client that reads a mock JSON response from `stdin`, allowing for deterministic testing of harness logic without relying on an external LLM.
-*   **State Management**: Conversations are serialized to and deserialized from JSON files. This includes the full message history (`history`), the active tool registry (`tools`), and harness configuration (`config`).
+*   **State Management**: Conversations are serialized to and deserialized from JSON files. This includes the full message history (`history`), the active tool registry (`tools`), and harness configuration (`config` including `base_url`, `model`, `max_tool_iterations`, `verbose`, and `depth`).
 
 ## 🛠️ How to Build
 
diff --git a/include/json_types.hpp b/include/json_types.hpp
index d9c87b8..0f051ed 100644
--- a/include/json_types.hpp
+++ b/include/json_types.hpp
@@ -362,8 +362,10 @@ struct HarnessConfig {
     size_t max_tool_iterations = 16;
     bool   verbose             = false;
     size_t depth               = 0;
+    std::string base_url       = "https://192.168.8.63/ollama";
+    std::string model          = "qwen3.6:35b-a3b-128k";
 };
-DRH_DEFINE_TYPE_OPTIONAL(HarnessConfig, max_tool_iterations, verbose, depth)
+DRH_DEFINE_TYPE_OPTIONAL(HarnessConfig, max_tool_iterations, verbose, depth, base_url, model)
 
 struct FunctionCall {
     std::string name = "";
diff --git a/include/ollama_client.hpp b/include/ollama_client.hpp
index 648061e..c63880c 100644
--- a/include/ollama_client.hpp
+++ b/include/ollama_client.hpp
@@ -9,15 +9,13 @@
 using http_req_cb_t = std::function<std::string(std::string const& old, std::string const& new_str)>;
 
 struct OllamaConfig {
-    std::string base_url = "https://192.168.8.63/ollama";
-    std::string model    = "qwen3.6:35b-a3b-128k";
     std::string auth_token = "";
     int         timeout_s = 60*10;
 };
 
 class OllamaClient : public Client {
 public:
-    explicit OllamaClient(OllamaConfig config = {});
+    explicit OllamaClient(std::string base_url, std::string model, OllamaConfig config = {});
     ~OllamaClient() override;
 
     std::expected<Message, std::string> chat(const std::vector<Message>& messages,
@@ -26,6 +24,8 @@ public:
     std::expected<std::vector<std::string>, std::string> list_models() const override;
 
 private:
+    std::string base_url_;
+    std::string model_;
     OllamaConfig config_;
     nlohmann::json build_body(const std::vector<Message>& messages,
                               const std::vector<Tool>& tools) const;
diff --git a/src/main.cpp b/src/main.cpp
index e33902a..63f86df 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -97,10 +97,11 @@ static HarnessState read_harness_state_or_exit(const char* file_path) {
 }
 
 int main(int argc, char** argv) {
-    OllamaConfig cfg;
+    HarnessConfig cfg;
+    OllamaConfig ollama_cfg;
     if (const char* m = std::getenv("OLLAMA_MODEL")) cfg.model    = m;
     if (const char* u = std::getenv("OLLAMA_URL"))   cfg.base_url = u;
-    if (const char* a = std::getenv("OLLAMA_AUTHORIZATION_TOKEN")) cfg.auth_token = a;
+    if (const char* a = std::getenv("OLLAMA_AUTHORIZATION_TOKEN")) ollama_cfg.auth_token = a;
 
     bool use_debug = false;
     bool debug_paths = false;
@@ -417,7 +418,7 @@ int main(int argc, char** argv) {
     auto create_client = [&](bool debug) -> std::unique_ptr<Client> {
         if (debug)
             return std::make_unique<DebugClient>();
-        return std::make_unique<OllamaClient>(cfg);
+        return std::make_unique<OllamaClient>(cfg.base_url, cfg.model, ollama_cfg);
     };
 
     // Scan for skills
@@ -647,7 +648,12 @@ int main(int argc, char** argv) {
         }
     }
 
-    Harness harness(create_client(use_debug), agent_tools, {.max_tool_iterations = 1000, .verbose = true});
+    Harness harness(create_client(use_debug), agent_tools, HarnessConfig{
+        .max_tool_iterations = 1000,
+        .verbose             = true,
+        .base_url            = cfg.base_url,
+        .model               = cfg.model
+    });
 
     if (!start_new)
     {
diff --git a/src/ollama_client.cpp b/src/ollama_client.cpp
index 1e2761b..e355dd8 100644
--- a/src/ollama_client.cpp
+++ b/src/ollama_client.cpp
@@ -7,7 +7,8 @@
 
 static int ollama_clients = 0;
 
-OllamaClient::OllamaClient(OllamaConfig config) : config_(std::move(config)) {
+OllamaClient::OllamaClient(std::string base_url, std::string model, OllamaConfig config) 
+    : base_url_(std::move(base_url)), model_(std::move(model)), config_(std::move(config)) {
     if (ollama_clients == 0)
         curl_global_init(CURL_GLOBAL_DEFAULT);
 
@@ -98,7 +99,7 @@ std::expected<std::string, std::string> OllamaClient::http_request(const std::st
 nlohmann::json OllamaClient::build_body(const std::vector<Message>& messages,
                                         const std::vector<Tool>& tools) const {
     nlohmann::json body = {
-        {"model",    config_.model},
+        {"model",    model_},
         {"stream",   true},
         {"messages", messages},
         {"stream_options", {
@@ -119,7 +120,7 @@ std::expected<Message, std::string> OllamaClient::chat(const std::vector<Message
                                 const std::vector<Tool>& tools) const {
     nlohmann::json body = build_body(messages, tools);
     std::string body_str = body.dump();
-    std::string url = config_.base_url + "/v1/chat/completions";
+    std::string url = base_url_ + "/v1/chat/completions";
 
     Message total{};
     Usage usage{};
@@ -227,7 +228,7 @@ std::expected<Message, std::string> OllamaClient::chat(const std::vector<Message
 }
 
 std::expected<std::vector<std::string>, std::string> OllamaClient::list_models() const {
-    std::string url = config_.base_url + "/api/tags";
+    std::string url = base_url_ + "/api/tags";
     auto response_result = http_request(url, "GET", "");
     if (!response_result) {
         return std::unexpected(response_result.error());
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
index 2b1686e..9040e5a 100644
--- a/tests/CMakeLists.txt
+++ b/tests/CMakeLists.txt
@@ -160,3 +160,6 @@ add_dr_test(test_print_history_multimodal)
 
 # Add encoding tests
 add_dr_test(test_encoding)
+
+# Add harness config tests (base_url and model in HarnessConfig)
+add_dr_test(test_harness_config)
diff --git a/tests/test_harness_config.sh b/tests/test_harness_config.sh
new file mode 100755
index 0000000..246eba9
--- /dev/null
+++ b/tests/test_harness_config.sh
@@ -0,0 +1,61 @@
+#!/bin/bash
+# test_harness_config.sh - Tests for HarnessConfig with base_url and model fields
+
+# Test 1: Verify config is saved with base_url and model in new conversations
+echo '{"choices":[{"delta":{"content":"Response","role":"assistant"},"finish_reason":"stop"}],"usage":{"completion_tokens":10,"prompt_tokens":5,"total_tokens":15}}' | "${DRHARNESS}" \
+    -F "${TEST_TEMP_DIR}/chat.json" \
+    -n \
+    -d \
+    -m "test" 2>/dev/null
+
+# Verify config contains base_url and model
+BASE_URL=$(cat "${TEST_TEMP_DIR}/chat.json" | jq -r '.config.base_url')
+MODEL=$(cat "${TEST_TEMP_DIR}/chat.json" | jq -r '.config.model')
+
+if [ -z "$BASE_URL" ] || [ "$BASE_URL" = "null" ]; then
+    echo "FAIL: Expected config.base_url to be set"
+    exit 1
+fi
+
+if [ -z "$MODEL" ] || [ "$MODEL" = "null" ]; then
+    echo "FAIL: Expected config.model to be set"
+    exit 1
+fi
+
+# Test 2: Verify -M flag sets model in config
+echo '{"choices":[{"delta":{"content":"Response","role":"assistant"},"finish_reason":"stop"}],"usage":{"completion_tokens":10,"prompt_tokens":5,"total_tokens":15}}' | "${DRHARNESS}" \
+    -F "${TEST_TEMP_DIR}/chat2.json" \
+    -n \
+    -d \
+    -M "custom-model" \
+    -m "test" 2>/dev/null
+
+MODEL2=$(cat "${TEST_TEMP_DIR}/chat2.json" | jq -r '.config.model')
+if [ "$MODEL2" != "custom-model" ]; then
+    echo "FAIL: Expected config.model to be 'custom-model', got '${MODEL2}'"
+    exit 1
+fi
+
+# Test 3: Verify backward compatibility - loading file without base_url and model
+echo '{"history":[{"role":"user","content":"hello"}],"tools":[],"config":{"max_tool_iterations":16,"verbose":false,"depth":0}}' > "${TEST_TEMP_DIR}/old_format.json"
+
+echo '{"choices":[{"delta":{"content":"Response","role":"assistant"},"finish_reason":"stop"}],"usage":{"completion_tokens":10,"prompt_tokens":5,"total_tokens":15}}' | "${DRHARNESS}" \
+    -F "${TEST_TEMP_DIR}/old_format.json" \
+    -d \
+    -m "test" 2>/dev/null
+
+# Verify the saved file now has base_url and model with defaults
+SAVED_BASE_URL=$(cat "${TEST_TEMP_DIR}/old_format.json" | jq -r '.config.base_url')
+SAVED_MODEL=$(cat "${TEST_TEMP_DIR}/old_format.json" | jq -r '.config.model')
+
+if [ -z "$SAVED_BASE_URL" ] || [ "$SAVED_BASE_URL" = "null" ]; then
+    echo "FAIL: Expected saved config.base_url to be set"
+    exit 1
+fi
+
+if [ -z "$SAVED_MODEL" ] || [ "$SAVED_MODEL" = "null" ]; then
+    echo "FAIL: Expected saved config.model to be set"
+    exit 1
+fi
+
+echo "All harness config tests passed"
diff --git a/tools/agent_tool.cpp b/tools/agent_tool.cpp
index adff7f1..150f3e0 100644
--- a/tools/agent_tool.cpp
+++ b/tools/agent_tool.cpp
@@ -48,14 +48,14 @@ Tool make_agent_tool(const AgentProfile& profile,
             }
             ToolRegistry sub_registry = std::move(sub_reg_result.value());
 
-            Harness harness(std::make_unique<OllamaClient>(OllamaConfig{
-                .base_url  = base_url,
-                .model     = profile.model,
+            Harness harness(std::make_unique<OllamaClient>(base_url, profile.model, OllamaConfig{
                 .timeout_s = 120
-            }), sub_registry, {
+            }), sub_registry, HarnessConfig{
                 .max_tool_iterations = 16,
                 .verbose             = true,
-                .depth               = depth
+                .depth               = depth,
+                .base_url            = base_url,
+                .model               = profile.model
             });
 
             auto result = harness.chat(task);