Replace BraintrustLogger with slf4j

build.gradle

@@ -21,47 +21,37 @@ repositories {
 }
 
 ext {
-  otelVersion = '1.36.0'
+  otelVersion = '1.54.1'
   jacksonVersion = '2.16.1'
-  junitVersion = '5.10.1'
-  assertjVersion = '3.25.1'
-  mockitoVersion = '5.8.0'
-  slf4jVersion = '2.0.9'
+  junitVersion = '5.11.4'
+  slf4jVersion = '2.0.17'
 }
 
 dependencies {
-  // OpenTelemetry
   api "io.opentelemetry:opentelemetry-api:${otelVersion}"
   api "io.opentelemetry:opentelemetry-sdk:${otelVersion}"
   api "io.opentelemetry:opentelemetry-sdk-trace:${otelVersion}"
   api "io.opentelemetry:opentelemetry-sdk-logs:${otelVersion}"
   implementation "io.opentelemetry:opentelemetry-exporter-otlp:${otelVersion}"
   implementation "io.opentelemetry:opentelemetry-exporter-logging:${otelVersion}"
   implementation "io.opentelemetry:opentelemetry-sdk-testing:${otelVersion}"
-  implementation "io.opentelemetry:opentelemetry-semconv:1.25.0-alpha"
+  implementation "io.opentelemetry:opentelemetry-semconv:1.30.1-alpha"
 
-  // HTTP Client (Java 11+)
-  implementation 'com.fasterxml.jackson.core:jackson-databind:' + jacksonVersion
-  implementation 'com.fasterxml.jackson.datatype:jackson-datatype-jsr310:' + jacksonVersion
-  implementation 'com.fasterxml.jackson.datatype:jackson-datatype-jdk8:' + jacksonVersion
+  implementation "com.fasterxml.jackson.core:jackson-databind:${jacksonVersion}"
+  implementation "com.fasterxml.jackson.datatype:jackson-datatype-jsr310:${jacksonVersion}"
+  implementation "com.fasterxml.jackson.datatype:jackson-datatype-jdk8:${jacksonVersion}"
 
-  // Logging
   implementation "org.slf4j:slf4j-api:${slf4jVersion}"
   runtimeOnly "org.slf4j:slf4j-simple:${slf4jVersion}"
 
-  // Utilities
-  implementation 'com.google.code.findbugs:jsr305:3.0.2' // @Nullable annotations
   implementation 'org.apache.commons:commons-lang3:3.14.0'
+  implementation 'com.google.code.findbugs:jsr305:3.0.2' // for @Nullable annotations
 
-  // AI SDKs (optional dependencies)
-  compileOnly 'com.openai:openai-java:2.8.1' // Official OpenAI SDK
+  compileOnly 'com.openai:openai-java:2.8.1'
   implementation "io.opentelemetry.instrumentation:opentelemetry-openai-java-1.1:2.19.0-alpha"
-  // compileOnly 'com.anthropic:anthropic-java:0.1.0' // Not yet available
 
-  // Testing
   testImplementation "org.junit.jupiter:junit-jupiter:${junitVersion}"
   testImplementation "org.junit.jupiter:junit-jupiter-params:${junitVersion}"
-  testImplementation "org.assertj:assertj-core:${assertjVersion}"
 }
 
 test {

examples/build.gradle

@@ -12,6 +12,8 @@ repositories {
   mavenCentral()
 }
 
+def braintrustLogLevel = System.getenv('BRAINTRUST_LOG_LEVEL') ?: 'info'
+
 dependencies {
   implementation project(':')
   // TODO: not sure why I have to do this. I would have expected this to come over in the project root transitive deps
@@ -33,20 +35,23 @@ task runSimpleOpenTelemetry(type: JavaExec) {
   description = 'Run the simple OpenTelemetry example'
   classpath = sourceSets.main.runtimeClasspath
   mainClass = 'dev.braintrust.examples.SimpleOpenTelemetryExample'
+  systemProperty 'org.slf4j.simpleLogger.log.dev.braintrust', braintrustLogLevel
 }
 
 task runCustomOpenTelemetry(type: JavaExec) {
   group = 'Braintrust SDK Examples'
   description = 'Run the custom OpenTelemetry example'
   classpath = sourceSets.main.runtimeClasspath
   mainClass = 'dev.braintrust.examples.CustomOpenTelemetryExample'
+  systemProperty 'org.slf4j.simpleLogger.log.dev.braintrust', braintrustLogLevel
 }
 
 task runOpenAIInstrumentation(type: JavaExec) {
   group = 'Braintrust SDK Examples'
   description = 'Run the OpenAI instrumentation example. NOTE: this requires OPENAI_API_KEY to be exported and will make a small call to openai, using your tokens'
   classpath = sourceSets.main.runtimeClasspath
   mainClass = 'dev.braintrust.examples.OpenAIInstrumentationExample'
+  systemProperty 'org.slf4j.simpleLogger.log.dev.braintrust', braintrustLogLevel
   debugOptions {
     enabled = true
     port = 5566
@@ -60,6 +65,7 @@ task runExperiment(type: JavaExec) {
   description = 'Run the experiment example'
   classpath = sourceSets.main.runtimeClasspath
   mainClass = 'dev.braintrust.examples.ExperimentExample'
+  systemProperty 'org.slf4j.simpleLogger.log.dev.braintrust', braintrustLogLevel
   debugOptions {
     enabled = true
     port = 5566

examples/src/main/java/dev/braintrust/examples/CustomOpenTelemetryExample.java

@@ -1,7 +1,6 @@
 package dev.braintrust.examples;
 
 import dev.braintrust.config.BraintrustConfig;
-import dev.braintrust.log.BraintrustLogger;
 import dev.braintrust.trace.BraintrustTracing;
 import io.opentelemetry.api.GlobalOpenTelemetry;
 import io.opentelemetry.exporter.otlp.http.logs.OtlpHttpLogRecordExporter;
@@ -88,7 +87,7 @@ private static void registerShutdownHook(OpenTelemetrySdk otel) {
                 .addShutdownHook(
                         new Thread(
                                 () -> {
-                                    BraintrustLogger.debug(
+                                    System.out.println(
                                             "Shutting down. Force-Flushing all otel data.");
                                     var result =
                                             CompletableResultCode.ofAll(
@@ -108,7 +107,7 @@ private static void registerShutdownHook(OpenTelemetrySdk otel) {
                                                                                     TimeUnit
                                                                                             .SECONDS))
                                                             .toList());
-                                    BraintrustLogger.debug(
+                                    System.out.println(
                                             "otel shutdown complete. Flush done: %s, Flush successful: %s"
                                                     .formatted(
                                                             result.isDone(), result.isSuccess()));

examples/src/main/java/dev/braintrust/examples/ExperimentExample.java

@@ -54,8 +54,6 @@ public static void main(String[] args) throws Exception {
                                         result -> "vegetable".equals(result) ? 1.0 : 0.0))
                         .build();
         var result = eval.run();
-        System.out.println(
-                "\n\n Example complete! View your data in Braintrust: "
-                        + result.createReportString());
+        System.out.println("\n\n" + result.createReportString());
     }
 }

src/main/java/dev/braintrust/api/BraintrustApiClient.java

@@ -6,7 +6,6 @@
 import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
 import com.fasterxml.jackson.datatype.jsr310.JavaTimeModule;
 import dev.braintrust.config.BraintrustConfig;
-import dev.braintrust.log.BraintrustLogger;
 import java.io.IOException;
 import java.net.URI;
 import java.net.http.HttpClient;
@@ -18,6 +17,7 @@
 import java.util.concurrent.CompletionException;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.ExecutionException;
+import lombok.extern.slf4j.Slf4j;
 
 public interface BraintrustApiClient {
     /** Creates or gets a project by name. */
@@ -39,6 +39,7 @@ static BraintrustApiClient of(BraintrustConfig config) {
         return new HttpImpl(config);
     }
 
+    @Slf4j
     class HttpImpl implements BraintrustApiClient {
         private final BraintrustConfig config;
         private final HttpClient httpClient;
@@ -170,25 +171,25 @@ private <T> CompletableFuture<T> postAsync(
         }
 
         private <T> CompletableFuture<T> sendAsync(HttpRequest request, Class<T> responseType) {
-            BraintrustLogger.debug("API Request: {} {}", request.method(), request.uri());
+            log.debug("API Request: {} {}", request.method(), request.uri());
 
             return httpClient
                     .sendAsync(request, HttpResponse.BodyHandlers.ofString())
                     .thenApply(response -> handleResponse(response, responseType));
         }
 
         private <T> T handleResponse(HttpResponse<String> response, Class<T> responseType) {
-            BraintrustLogger.debug("API Response: {} - {}", response.statusCode(), response.body());
+            log.debug("API Response: {} - {}", response.statusCode(), response.body());
 
             if (response.statusCode() >= 200 && response.statusCode() < 300) {
                 try {
                     return objectMapper.readValue(response.body(), responseType);
                 } catch (IOException e) {
-                    BraintrustLogger.warn("Failed to parse response body", e);
+                    log.warn("Failed to parse response body", e);
                     throw new ApiException("Failed to parse response body", e);
                 }
             } else {
-                BraintrustLogger.warn(
+                log.warn(
                         "API request failed with status {}: {}",
                         response.statusCode(),
                         response.body());
@@ -225,6 +226,7 @@ private static ObjectMapper createObjectMapper() {
     }
 
     /** Implementation for test doubling */
+    @Slf4j
     class InMemoryImpl implements BraintrustApiClient {
         private final List<OrganizationAndProjectInfo> organizationAndProjectInfos;
         private final Set<Experiment> experiments =

src/main/java/dev/braintrust/config/BraintrustConfig.java

@@ -31,8 +31,8 @@ public final class BraintrustConfig extends BaseConfig {
             Duration.ofSeconds(getConfig("BRAINTRUST_REQUEST_TIMEOUT", 30));
 
     /** Setting for unit testing. Do not use in production. */
-    private final boolean unitTetJavaExportSpansInMemory =
-            getConfig("BRAINTRUST_TEST_JAVA_EXPORT_SPANS_IN_MEMORY", false);
+    private final boolean exportSpansInMemoryForUnitTest =
+            getConfig("BRAINTRUST_JAVA_EXPORT_SPANS_IN_MEMORY_FOR_UNIT_TEST", false);
 
     public static BraintrustConfig fromEnvironment() {
         return of();

src/main/java/dev/braintrust/instrumentation/openai/otel/ChatCompletionEventsHelper.java

@@ -20,7 +20,6 @@
 import com.openai.models.chat.completions.ChatCompletionSystemMessageParam;
 import com.openai.models.chat.completions.ChatCompletionToolMessageParam;
 import com.openai.models.chat.completions.ChatCompletionUserMessageParam;
-import dev.braintrust.log.BraintrustLogger;
 import io.opentelemetry.api.common.AttributeKey;
 import io.opentelemetry.api.common.Value;
 import io.opentelemetry.api.logs.LogRecordBuilder;
@@ -37,7 +36,9 @@
 import java.util.Optional;
 import java.util.stream.Collectors;
 import javax.annotation.Nullable;
+import lombok.extern.slf4j.Slf4j;
 
+@Slf4j
 final class ChatCompletionEventsHelper {
 
     private static final AttributeKey<String> EVENT_NAME = stringKey("event.name");
@@ -76,7 +77,7 @@ public static void emitPromptLogEvents(
                                         "braintrust.input_json",
                                         JSON_MAPPER.writeValueAsString(content));
                     } catch (JsonProcessingException e) {
-                        BraintrustLogger.error("Error mapping json", e);
+                        log.error("Error mapping json", e);
                     }
                     body.put("content", Value.of(content));
                 }
@@ -200,7 +201,7 @@ public static void emitCompletionLogEvents(
             var completionJson = JSON_MAPPER.writeValueAsString(completion);
             Span.current().setAttribute("braintrust.output_json", completionJson);
         } catch (JsonProcessingException e) {
-            BraintrustLogger.error("Error mapping completion json", e);
+            log.error("Error mapping completion json", e);
         }
         for (ChatCompletion.Choice choice : completion.choices()) {
             ChatCompletionMessage choiceMsg = choice.message();