diff --git a/include/ai/core.h b/include/ai/core.h
index 05fb2fc..2b8ecf8 100644
--- a/include/ai/core.h
+++ b/include/ai/core.h
@@ -31,9 +31,6 @@
 /// #include <ai/core.h>
 ///
 /// // Use core types like ai::GenerateOptions, ai::Message, etc.
-/// ai::GenerateOptions options{
-///     .model = "some-model",
-///     .prompt = "Hello world"
-/// };
+/// ai::GenerateOptions options("some-model", "Hello world");
 /// ```
 namespace ai {}
\ No newline at end of file
diff --git a/include/ai/logger.h b/include/ai/logger.h
index 6aff531..7968a2d 100644
--- a/include/ai/logger.h
+++ b/include/ai/logger.h
@@ -107,21 +107,55 @@ class ConsoleLogger final : public Logger {
 
 namespace detail {
 
+#if defined(__cpp_lib_atomic_shared_ptr)
+
+inline std::atomic<std::shared_ptr<Logger>>& logger_instance() {
+  static std::atomic<std::shared_ptr<Logger>> instance(
+      std::make_shared<ConsoleLogger>());
+  return instance;
+}
+
+inline std::shared_ptr<Logger> load_logger() {
+  return logger_instance().load();
+}
+
+inline void store_logger(std::shared_ptr<Logger> logger) {
+  logger_instance().store(std::move(logger));
+}
+
+#else
+// Fall back to the atomic shared_ptr free functions on standard libraries
+// that have not implemented std::atomic<std::shared_ptr> (notably libc++).
+
 inline std::shared_ptr<Logger>& logger_instance() {
   static std::shared_ptr<Logger> instance = std::make_shared<ConsoleLogger>();
   return instance;
 }
 
+inline std::shared_ptr<Logger> load_logger() {
+  return std::atomic_load(&logger_instance());
+}
+
+inline void store_logger(std::shared_ptr<Logger> logger) {
+  std::atomic_store(&logger_instance(), std::move(logger));
+}
+
+#endif
+
 }  // namespace detail
 
 inline void install_logger(std::shared_ptr<Logger> logger) {
   if (logger) {
-    std::atomic_store(&detail::logger_instance(), std::move(logger));
+    detail::store_logger(std::move(logger));
   }
 }
 
+/// Returns the currently installed logger. The reference stays valid until
+/// the next logger()/log_* call on the same thread; do not cache it across
+/// calls that may log.
 inline Logger& logger() {
-  auto ptr = std::atomic_load(&detail::logger_instance());
+  thread_local std::shared_ptr<Logger> ptr;
+  ptr = detail::load_logger();
   return *ptr;
 }
 
diff --git a/src/langfuse/tracer.cpp b/src/langfuse/tracer.cpp
index d0e966d..503802f 100644
--- a/src/langfuse/tracer.cpp
+++ b/src/langfuse/tracer.cpp
@@ -532,7 +532,7 @@ std::string Trace::to_iso8601(std::chrono::system_clock::time_point t) {
 #else
   gmtime_r(&tt, &tm);
 #endif
-  char buf[40];
+  char buf[80];
   std::snprintf(buf, sizeof(buf), "%04d-%02d-%02dT%02d:%02d:%02d.%03lldZ",
                 tm.tm_year + 1900, tm.tm_mon + 1, tm.tm_mday, tm.tm_hour,
                 tm.tm_min, tm.tm_sec, static_cast<long long>(ms));
diff --git a/src/providers/anthropic/anthropic_factory.cpp b/src/providers/anthropic/anthropic_factory.cpp
index bc6540c..9fae17b 100644
--- a/src/providers/anthropic/anthropic_factory.cpp
+++ b/src/providers/anthropic/anthropic_factory.cpp
@@ -2,8 +2,8 @@
 
 #include "ai/errors.h"
 #include "anthropic_client.h"
+#include "utils/env_utils.h"
 
-#include <cstdlib>
 #include <memory>
 #include <optional>
 
@@ -18,13 +18,13 @@ std::string get_api_key_or_default(const std::string& api_key) {
     return api_key;
   }
 
-  const char* env_api_key = std::getenv("ANTHROPIC_API_KEY");
+  auto env_api_key = utils::non_empty_env("ANTHROPIC_API_KEY");
   if (!env_api_key) {
     throw ConfigurationError(
         "API key not provided and ANTHROPIC_API_KEY environment variable not "
         "set");
   }
-  return env_api_key;
+  return *std::move(env_api_key);
 }
 
 std::string get_base_url_or_default(const std::string& base_url) {
@@ -48,12 +48,12 @@ Client create_client(const std::string& api_key, const std::string& base_url) {
 }
 
 std::optional<Client> try_create_client() {
-  const char* api_key = std::getenv("ANTHROPIC_API_KEY");
+  auto api_key = utils::non_empty_env("ANTHROPIC_API_KEY");
   if (!api_key) {
     return std::nullopt;
   }
-  return Client(std::make_unique<AnthropicClient>(api_key, kDefaultBaseUrl));
+  return Client(std::make_unique<AnthropicClient>(*api_key, kDefaultBaseUrl));
 }
 
 }  // namespace anthropic
-}  // namespace ai
\ No newline at end of file
+}  // namespace ai
diff --git a/src/providers/anthropic/anthropic_response_parser.cpp b/src/providers/anthropic/anthropic_response_parser.cpp
index 4789730..a78bbe1 100644
--- a/src/providers/anthropic/anthropic_response_parser.cpp
+++ b/src/providers/anthropic/anthropic_response_parser.cpp
@@ -103,7 +103,7 @@ EmbeddingResult AnthropicResponseParser::parse_success_embedding_response(
 
   // Extract choices
   if (response.contains("data") && !response["data"].empty()) {
-    result.data = std::move(response["data"]);
+    result.data = response["data"];
   }
 
   // Extract usage
@@ -150,4 +150,4 @@ FinishReason AnthropicResponseParser::parse_stop_reason(
 }
 
 }  // namespace anthropic
-}  // namespace ai
\ No newline at end of file
+}  // namespace ai
diff --git a/src/providers/base_provider_client.cpp b/src/providers/base_provider_client.cpp
index 9484724..24c16d1 100644
--- a/src/providers/base_provider_client.cpp
+++ b/src/providers/base_provider_client.cpp
@@ -140,6 +140,7 @@ GenerateResult BaseProviderClient::generate_text_single_step(
 }
 
 StreamResult BaseProviderClient::stream_text(const StreamOptions& options) {
+  (void)options;
   // This needs to be implemented with provider-specific stream implementations
   // For now, return an error
   ai::logger::log_error("Streaming not yet implemented in BaseProviderClient");
@@ -197,4 +198,4 @@ EmbeddingResult BaseProviderClient::embeddings(
 }
 
 }  // namespace providers
-}  // namespace ai
\ No newline at end of file
+}  // namespace ai
diff --git a/src/providers/openai/openai_factory.cpp b/src/providers/openai/openai_factory.cpp
index 808e841..da9eb28 100644
--- a/src/providers/openai/openai_factory.cpp
+++ b/src/providers/openai/openai_factory.cpp
@@ -2,8 +2,8 @@
 
 #include "ai/errors.h"
 #include "openai_client.h"
+#include "utils/env_utils.h"
 
-#include <cstdlib>
 #include <memory>
 #include <optional>
 
@@ -18,12 +18,12 @@ std::string get_api_key_or_default(const std::string& api_key) {
     return api_key;
   }
 
-  const char* env_api_key = std::getenv("OPENAI_API_KEY");
+  auto env_api_key = utils::non_empty_env("OPENAI_API_KEY");
   if (!env_api_key) {
     throw ConfigurationError(
         "API key not provided and OPENAI_API_KEY environment variable not set");
   }
-  return env_api_key;
+  return *std::move(env_api_key);
 }
 
 std::string get_base_url_or_default(const std::string& base_url) {
@@ -55,12 +55,12 @@ Client create_client(const std::string& api_key,
 }
 
 std::optional<Client> try_create_client() {
-  const char* api_key = std::getenv("OPENAI_API_KEY");
+  auto api_key = utils::non_empty_env("OPENAI_API_KEY");
   if (!api_key) {
     return std::nullopt;
   }
-  return Client(std::make_unique<OpenAIClient>(api_key, kDefaultBaseUrl));
+  return Client(std::make_unique<OpenAIClient>(*api_key, kDefaultBaseUrl));
 }
 
 }  // namespace openai
-}  // namespace ai
\ No newline at end of file
+}  // namespace ai
diff --git a/src/providers/openai/openai_response_parser.cpp b/src/providers/openai/openai_response_parser.cpp
index 0274956..9709706 100644
--- a/src/providers/openai/openai_response_parser.cpp
+++ b/src/providers/openai/openai_response_parser.cpp
@@ -145,7 +145,7 @@ EmbeddingResult OpenAIResponseParser::parse_success_embedding_response(
 
   // Extract choices
   if (response.contains("data") && !response["data"].empty()) {
-    result.data = std::move(response["data"]);
+    result.data = response["data"];
   }
 
   // Extract usage
@@ -192,4 +192,4 @@ FinishReason OpenAIResponseParser::parse_finish_reason(
 }
 
 }  // namespace openai
-}  // namespace ai
\ No newline at end of file
+}  // namespace ai
diff --git a/src/tools/tool_executor.cpp b/src/tools/tool_executor.cpp
index 29c1185..0d3e2cc 100644
--- a/src/tools/tool_executor.cpp
+++ b/src/tools/tool_executor.cpp
@@ -232,6 +232,7 @@ Tool create_simple_tool(const std::string& name,
                         const std::string& description,
                         const std::map<std::string, std::string>& parameters,
                         ToolExecuteFunction execute_func) {
+  (void)name;  // The ToolSet key is the canonical tool name.
   JsonValue schema = create_object_schema(parameters);
   return create_tool(description, schema, std::move(execute_func));
 }
@@ -241,6 +242,7 @@ Tool create_simple_async_tool(
     const std::string& description,
     const std::map<std::string, std::string>& parameters,
     AsyncToolExecuteFunction execute_func) {
+  (void)name;  // The ToolSet key is the canonical tool name.
   JsonValue schema = create_object_schema(parameters);
   return create_async_tool(description, schema, std::move(execute_func));
 }
@@ -280,4 +282,4 @@ std::string generate_tool_call_id() {
   return id;
 }
 
-}  // namespace ai
\ No newline at end of file
+}  // namespace ai
diff --git a/src/utils/env_utils.h b/src/utils/env_utils.h
new file mode 100644
index 0000000..29ce392
--- /dev/null
+++ b/src/utils/env_utils.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include <cstdlib>
+#include <optional>
+#include <string>
+
+namespace ai {
+namespace utils {
+
+/// Read an environment variable, treating unset and empty values as absent.
+inline std::optional<std::string> non_empty_env(const char* name) {
+  const char* value = std::getenv(name);
+  if (!value || *value == '\0') {
+    return std::nullopt;
+  }
+  return std::string(value);
+}
+
+}  // namespace utils
+}  // namespace ai