diff --git a/dd-trace-core/src/main/java/datadog/trace/core/CoreTracer.java b/dd-trace-core/src/main/java/datadog/trace/core/CoreTracer.java
index 28f9e39c710..ba88574b375 100644
--- a/dd-trace-core/src/main/java/datadog/trace/core/CoreTracer.java
+++ b/dd-trace-core/src/main/java/datadog/trace/core/CoreTracer.java
@@ -72,6 +72,7 @@
 import datadog.trace.bootstrap.instrumentation.api.ProfilingContextIntegration;
 import datadog.trace.bootstrap.instrumentation.api.SpanAttributes;
 import datadog.trace.bootstrap.instrumentation.api.SpanLink;
+import datadog.trace.bootstrap.instrumentation.api.SpanPrototype;
 import datadog.trace.bootstrap.instrumentation.api.TagContext;
 import datadog.trace.bootstrap.instrumentation.api.Tags;
 import datadog.trace.civisibility.interceptor.CiVisibilityApmProtocolInterceptor;
@@ -1038,6 +1039,24 @@ public CoreSpanBuilder buildSpan(
     return createMultiSpanBuilder(instrumentationName, operationName);
   }
 
+  /**
+   * Seeds identity (instrumentation name, operation, span type) and tags from a prototype.
+   *
+   * <p>TODO(follow-up): eager-sets identity from the proto today, which is fine while
+   * {@code buildSpan(proto)} is the only proto entry point. When a builder value and a proto value
+   * can coexist, resolve via helpers (builder-explicit wins, proto is the fallback) in the build
+   * path and make this carry-only — no reach-in to {@code builder.spanType}/{@code spanPrototype}.
+   */
+  public CoreSpanBuilder buildSpan(final SpanPrototype prototype) {
+    CoreSpanBuilder builder =
+        createMultiSpanBuilder(prototype.instrumentationName(), prototype.operationName());
+    builder.spanPrototype = prototype;
+    if (prototype.spanType() != null) {
+      builder.spanType = prototype.spanType();
+    }
+    return builder;
+  }
+
   MultiSpanBuilder createMultiSpanBuilder(
       final String instrumentationName, final CharSequence operationName) {
     return new MultiSpanBuilder(this, instrumentationName, operationName);
@@ -1583,6 +1602,7 @@ public abstract static class CoreSpanBuilder implements AgentTracer.SpanBuilder
     // Builder attributes
     // Make sure any fields added here are also reset properly in ReusableSingleSpanBuilder.reset
     protected TagMap.Ledger tagLedger;
+    protected SpanPrototype spanPrototype = SpanPrototype.NONE;
     protected long timestampMicro;
     protected AgentSpanContext parent;
     protected String serviceName;
@@ -1621,6 +1641,7 @@ protected static final DDSpan buildSpan(
         boolean errorFlag,
         CharSequence spanType,
         TagMap.Ledger tagLedger,
+        SpanPrototype spanPrototype,
         List<AgentSpanLink> links,
         Object builderRequestContextDataAppSec,
         Object builderRequestContextDataIast,
@@ -1640,6 +1661,7 @@ protected static final DDSpan buildSpan(
               errorFlag,
               spanType,
               tagLedger,
+              spanPrototype,
               links,
               builderRequestContextDataAppSec,
               builderRequestContextDataIast,
@@ -1725,6 +1747,7 @@ protected AgentSpan startImpl() {
           this.errorFlag,
           this.spanType,
           this.tagLedger,
+          this.spanPrototype,
           this.links,
           this.builderRequestContextDataAppSec,
           this.builderRequestContextDataIast,
@@ -1751,6 +1774,7 @@ protected static final AgentSpan startSpan(
           false /* errorFlag */,
           null /* spanType */,
           null /* tagLedger */,
+          SpanPrototype.NONE /* spanPrototype */,
           null /* links */,
           null /* appSec */,
           null /* iast */,
@@ -1770,6 +1794,7 @@ protected static final AgentSpan startSpan(
         boolean errorFlag,
         CharSequence spanType,
         TagMap.Ledger tagLedger,
+        SpanPrototype spanPrototype,
         List<AgentSpanLink> links,
         Object builderRequestContextDataAppSec,
         Object builderRequestContextDataIast,
@@ -1820,6 +1845,7 @@ protected static final AgentSpan startSpan(
           errorFlag,
           spanType,
           tagLedger,
+          spanPrototype,
           links,
           builderRequestContextDataAppSec,
           builderRequestContextDataIast,
@@ -1958,6 +1984,7 @@ protected static final DDSpanContext buildSpanContext(
         boolean errorFlag,
         CharSequence spanType,
         TagMap.Ledger tagLedger,
+        SpanPrototype spanPrototype,
         List<AgentSpanLink> links,
         Object builderRequestContextDataAppSec,
         Object builderRequestContextDataIast,
@@ -2196,6 +2223,9 @@ protected static final DDSpanContext buildSpanContext(
       // the builder. This is the order that the tags were added previously, but maybe the `tags`
       // set in the builder should come last, so that they override other tags.
       context.setAllTags(mergedTracerTags, mergedTracerTagsNeedsIntercept);
+      if (spanPrototype != SpanPrototype.NONE) {
+        context.setAllTags(spanPrototype.tags());
+      }
       context.setAllTags(tagLedger);
       context.setAllTags(coreTags, coreTagsNeedsIntercept);
       context.setAllTags(rootSpanTags, rootSpanTagsNeedsIntercept);
@@ -2276,6 +2306,7 @@ final boolean reset(String instrumentationName, CharSequence operationName) {
       this.operationName = operationName;
 
       if (this.tagLedger != null) this.tagLedger.reset();
+      this.spanPrototype = SpanPrototype.NONE;
       this.timestampMicro = 0L;
       this.parent = null;
       this.serviceName = null;