braintrustdata · Andrew Kent (realark) · Oct 23, 2025 · Oct 21, 2025 · Oct 22, 2025 · Oct 23, 2025
diff --git a/README.md b/README.md
@@ -31,8 +31,8 @@ dependencies {
 ### Evals
 
 ```java
-var config = BraintrustConfig.fromEnvironment();
-var openTelemetry = BraintrustTracing.of(config, true);
+var braintrust = Braintrust.get();
+var openTelemetry = braintrust.openTelemetryCreate();
 var openAIClient = BraintrustOpenAI.wrapOpenAI(openTelemetry, OpenAIOkHttpClient.fromEnv());
 
 Function<String, String> getFoodType =
@@ -49,11 +49,8 @@ Function<String, String> getFoodType =
             return response.choices().get(0).message().content().orElse("").toLowerCase();
         };
 
-var eval =
-        Eval.<String, String>builder()
+var eval = braintrust.<String, String>evalBuilder()
                 .name("java-eval-x-" + System.currentTimeMillis())
-                .tracer(BraintrustTracing.getTracer(openTelemetry))
-                .config(config)
                 .cases(
                         EvalCase.of("asparagus", "vegetable"),
                         EvalCase.of("banana", "fruit"))
@@ -73,8 +70,8 @@ System.out.println("\n\n" + result.createReportString());
 ### OpenAI Tracing
 
 ```java
-var braintrustConfig = BraintrustConfig.fromEnvironment();
-var openTelemetry = BraintrustTracing.of(braintrustConfig, true);
+var braintrust = Braintrust.get();
+var openTelemetry = braintrust.openTelemetryCreate();
 OpenAIClient openAIClient = BraintrustOpenAI.wrapOpenAI(openTelemetry, OpenAIOkHttpClient.fromEnv());
 
 var request =

diff --git a/build.gradle b/build.gradle
@@ -66,6 +66,8 @@ dependencies {
   implementation 'org.apache.commons:commons-lang3:3.14.0'
   implementation 'com.google.code.findbugs:jsr305:3.0.2' // for @Nullable annotations
 
+  implementation "com.github.spullara.mustache.java:compiler:0.9.14"
+
   testImplementation "org.slf4j:slf4j-simple:${slf4jVersion}"
   testImplementation "io.opentelemetry:opentelemetry-sdk-testing:${otelVersion}"
   testImplementation "org.junit.jupiter:junit-jupiter:${junitVersion}"
@@ -219,7 +221,7 @@ jar {
       'Implementation-Title': 'Braintrust Java SDK',
       'Implementation-Version': version,
       'Implementation-Vendor': 'Braintrust',
-      'Main-Class': 'dev.braintrust.trace.SDKMain'
+      'Main-Class': 'dev.braintrust.SDKMain'
     )
   }
 }

diff --git a/examples/src/main/java/dev/braintrust/examples/AnthropicInstrumentationExample.java b/examples/src/main/java/dev/braintrust/examples/AnthropicInstrumentationExample.java
@@ -4,9 +4,8 @@
 import com.anthropic.client.okhttp.AnthropicOkHttpClient;
 import com.anthropic.models.messages.MessageCreateParams;
 import com.anthropic.models.messages.Model;
-import dev.braintrust.config.BraintrustConfig;
+import dev.braintrust.Braintrust;
 import dev.braintrust.instrumentation.anthropic.BraintrustAnthropic;
-import dev.braintrust.trace.BraintrustTracing;
 
 /** Basic OTel + Anthropic instrumentation example */
 public class AnthropicInstrumentationExample {
@@ -18,9 +17,9 @@ public static void main(String[] args) throws Exception {
                             + " fail.\n");
         }
 
-        var braintrustConfig = BraintrustConfig.fromEnvironment();
-        var openTelemetry = BraintrustTracing.of(braintrustConfig, true);
-        var tracer = BraintrustTracing.getTracer(openTelemetry);
+        var braintrust = Braintrust.get();
+        var openTelemetry = braintrust.openTelemetryCreate();
+        var tracer = openTelemetry.getTracer("my-instrumentation");
 
         // Wrap Anthropic client with Braintrust instrumentation
         AnthropicClient anthropicClient =
@@ -35,7 +34,7 @@ public static void main(String[] args) throws Exception {
         }
 
         var url =
-                braintrustConfig.fetchProjectURI()
+                braintrust.projectUri()
                         + "/logs?r=%s&s=%s"
                                 .formatted(
                                         rootSpan.getSpanContext().getTraceId(),

diff --git a/examples/src/main/java/dev/braintrust/examples/CustomOpenTelemetryExample.java b/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.trace.BraintrustTracing;
+import dev.braintrust.Braintrust;
 import io.opentelemetry.api.GlobalOpenTelemetry;
 import io.opentelemetry.exporter.otlp.http.logs.OtlpHttpLogRecordExporter;
 import io.opentelemetry.exporter.otlp.http.metrics.OtlpHttpMetricExporter;
@@ -51,8 +50,8 @@ public static void main(String[] args) throws Exception {
         // NOTE: there are many ways to set up otel builders, etc.
         // The important line is here: call enable with your otel builders and braintrust will
         // export open telemetry data in addition to your existing setup
-        var braintrustConfig = BraintrustConfig.fromEnvironment();
-        BraintrustTracing.enable(braintrustConfig, tracerBuilder, loggerBuilder, meterBuilder);
+        var braintrust = Braintrust.get();
+        braintrust.openTelemetryEnable(tracerBuilder, loggerBuilder, meterBuilder);
 
         var openTelemetry =
                 OpenTelemetrySdk.builder()
@@ -74,7 +73,7 @@ public static void main(String[] args) throws Exception {
             span.end();
         }
         var url =
-                braintrustConfig.fetchProjectURI()
+                braintrust.projectUri()
                         + "/logs?r=%s&s=%s"
                                 .formatted(
                                         span.getSpanContext().getTraceId(),

diff --git a/examples/src/main/java/dev/braintrust/examples/ExperimentExample.java b/examples/src/main/java/dev/braintrust/examples/ExperimentExample.java
@@ -3,18 +3,16 @@
 import com.openai.client.okhttp.OpenAIOkHttpClient;
 import com.openai.models.ChatModel;
 import com.openai.models.chat.completions.ChatCompletionCreateParams;
-import dev.braintrust.config.BraintrustConfig;
-import dev.braintrust.eval.Eval;
+import dev.braintrust.Braintrust;
 import dev.braintrust.eval.EvalCase;
 import dev.braintrust.eval.Scorer;
 import dev.braintrust.instrumentation.openai.BraintrustOpenAI;
-import dev.braintrust.trace.BraintrustTracing;
 import java.util.function.Function;
 
 public class ExperimentExample {
     public static void main(String[] args) throws Exception {
-        var config = BraintrustConfig.fromEnvironment();
-        var openTelemetry = BraintrustTracing.of(config, true);
+        var braintrust = Braintrust.get();
+        var openTelemetry = braintrust.openTelemetryCreate();
         var openAIClient = BraintrustOpenAI.wrapOpenAI(openTelemetry, OpenAIOkHttpClient.fromEnv());
 
         Function<String, String> getFoodType =
@@ -32,13 +30,12 @@ public static void main(String[] args) throws Exception {
                 };
 
         var eval =
-                Eval.<String, String>builder()
+                braintrust
+                        .<String, String>evalBuilder()
                         .name("java-eval-x-" + System.currentTimeMillis()) // NOTE: if you use a
                         // constant, additional runs
                         // will append new cases to
                         // the same experiment
-                        .tracer(BraintrustTracing.getTracer(openTelemetry))
-                        .config(config)
                         .cases(
                                 EvalCase.of("strawberry", "fruit"),
                                 EvalCase.of("asparagus", "vegetable"),

diff --git a/examples/src/main/java/dev/braintrust/examples/OpenAIInstrumentationExample.java b/examples/src/main/java/dev/braintrust/examples/OpenAIInstrumentationExample.java
@@ -5,31 +5,34 @@
 import com.openai.models.ChatModel;
 import com.openai.models.chat.completions.ChatCompletionCreateParams;
 import com.openai.models.chat.completions.ChatCompletionStreamOptions;
-import dev.braintrust.config.BraintrustConfig;
+import dev.braintrust.Braintrust;
 import dev.braintrust.instrumentation.openai.BraintrustOpenAI;
-import dev.braintrust.trace.BraintrustTracing;
 
 /** Basic OTel + OpenAI instrumentation example */
 public class OpenAIInstrumentationExample {
+
     public static void main(String[] args) throws Exception {
         if (null == System.getenv("OPENAI_API_KEY")) {
             System.err.println(
                     "\nWARNING envar OPEN_AI_API_KEY not found. This example will likely fail.\n");
         }
-        var braintrustConfig = BraintrustConfig.fromEnvironment();
-        var openTelemetry = BraintrustTracing.of(braintrustConfig, true);
-        var tracer = BraintrustTracing.getTracer(openTelemetry);
+        var braintrust = Braintrust.get();
+        var openTelemetry = braintrust.openTelemetryCreate();
         OpenAIClient openAIClient =
                 BraintrustOpenAI.wrapOpenAI(openTelemetry, OpenAIOkHttpClient.fromEnv());
-        var rootSpan = tracer.spanBuilder("openai-java-instrumentation-example").startSpan();
+        var rootSpan =
+                openTelemetry
+                        .getTracer("my-instrumentation")
+                        .spanBuilder("openai-java-instrumentation-example")
+                        .startSpan();
         try (var ignored = rootSpan.makeCurrent()) {
             chatCompletionsExample(openAIClient);
             // chatCompletionsStreamingExample(openAIClient);
         } finally {
             rootSpan.end();
         }
         var url =
-                braintrustConfig.fetchProjectURI()
+                braintrust.projectUri()
                         + "/logs?r=%s&s=%s"
                                 .formatted(
                                         rootSpan.getSpanContext().getTraceId(),

diff --git a/examples/src/main/java/dev/braintrust/examples/PromptFetchingExample.java b/examples/src/main/java/dev/braintrust/examples/PromptFetchingExample.java
@@ -0,0 +1,59 @@
+package dev.braintrust.examples;
+
+import static dev.braintrust.instrumentation.openai.BraintrustOpenAI.buildChatCompletionsPrompt;
+import static dev.braintrust.instrumentation.openai.BraintrustOpenAI.wrapOpenAI;
+
+import com.openai.client.OpenAIClient;
+import com.openai.client.okhttp.OpenAIOkHttpClient;
+import dev.braintrust.Braintrust;
+import dev.braintrust.prompt.BraintrustPromptLoader.PromptLoadRequest;
+import java.util.Map;
+
+public class PromptFetchingExample {
+    public static void main(String... args) {
+        if (null == System.getenv("OPENAI_API_KEY")) {
+            System.err.println(
+                    "\nWARNING envar OPEN_AI_API_KEY not found. This example will likely fail.\n");
+        }
+        var braintrust = Braintrust.get();
+        var openTelemetry = braintrust.openTelemetryCreate();
+
+        OpenAIClient openAIClient = wrapOpenAI(openTelemetry, OpenAIOkHttpClient.fromEnv());
+
+        { // simple example
+            var prompt = braintrust.promptLoader().load("kind-greeter-69d2");
+            var response =
+                    openAIClient
+                            .chat()
+                            .completions()
+                            .create(
+                                    buildChatCompletionsPrompt(
+                                            prompt, Map.of("name", "Sam Malone")));
+            System.out.println("got response: %s".formatted(response.choices().get(0).message()));
+        }
+        { // more complex prompt options
+            var prompt =
+                    braintrust
+                            .promptLoader()
+                            .load(
+                                    PromptLoadRequest.builder()
+                                            .projectName("andrew-misc")
+                                            .promptSlug("unkind-greeter-fd4c")
+                                            .version("cbbc711da9f7d445")
+                                            .defaults("model", "gpt-3.5-turbo")
+                                            .build());
+            var response =
+                    openAIClient
+                            .chat()
+                            .completions()
+                            .create(
+                                    buildChatCompletionsPrompt(
+                                            prompt, Map.of("name", "Frasier Crane")));
+            System.out.println("got response: %s".formatted(response));
+        }
+
+        System.out.println(
+                "\n\n  Example complete! View your data in Braintrust: %s\n"
+                        .formatted(braintrust.projectUri() + "/logs"));
+    }
+}
diff --git a/examples/src/main/java/dev/braintrust/examples/SimpleOpenTelemetryExample.java b/examples/src/main/java/dev/braintrust/examples/SimpleOpenTelemetryExample.java
@@ -1,13 +1,12 @@
 package dev.braintrust.examples;
 
-import dev.braintrust.config.BraintrustConfig;
-import dev.braintrust.trace.BraintrustTracing;
+import dev.braintrust.Braintrust;
 
 public class SimpleOpenTelemetryExample {
     public static void main(String[] args) throws Exception {
-        var braintrustConfig = BraintrustConfig.fromEnvironment();
-        var openTelemetry = BraintrustTracing.quickstart();
-        var tracer = BraintrustTracing.getTracer(openTelemetry);
+        var braintrust = Braintrust.get();
+        var openTelemetry = braintrust.openTelemetryCreate();
+        var tracer = openTelemetry.getTracer("my-instrumentation");
 
         var span = tracer.spanBuilder("hello-java").startSpan();
         try (var ignored = span.makeCurrent()) {
@@ -18,7 +17,7 @@ public static void main(String[] args) throws Exception {
             span.end();
         }
         var url =
-                braintrustConfig.fetchProjectURI()
+                braintrust.projectUri()
                         + "/logs?r=%s&s=%s"
                                 .formatted(
                                         span.getSpanContext().getTraceId(),