diff --git a/sandbox/build.gradle b/sandbox/build.gradle
index 4a14d0a11a0d7..1ee3608a4bc10 100644
--- a/sandbox/build.gradle
+++ b/sandbox/build.gradle
@@ -41,6 +41,7 @@ def patchedCalciteVersion = "${libVersions['calcite']}-opensearch-${libVersions[
 
 subprojects {
   group = 'org.opensearch.sandbox'
+  ext.patchedCalciteVersion = patchedCalciteVersion
 
   // The patched calcite-core / calcite-linq4j live in the OpenSearch
   // snapshots Maven repo; analytics-framework advertises them as `api`,
diff --git a/sandbox/libs/analytics-api/build.gradle b/sandbox/libs/analytics-api/build.gradle
new file mode 100644
index 0000000000000..1d39a279f02b9
--- /dev/null
+++ b/sandbox/libs/analytics-api/build.gradle
@@ -0,0 +1,30 @@
+/*
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * The OpenSearch Contributors require contributions made to
+ * this file be licensed under the Apache-2.0 license or a
+ * compatible open source license.
+ */
+
+/*
+ * Analytics Engine API surface consumable from JDK 21 code paths.
+ */
+
+java { sourceCompatibility = JavaVersion.toVersion(21); targetCompatibility = JavaVersion.toVersion(21) }
+
+// no test for now, so disable
+testingConventions.enabled = false
+
+dependencies {
+  compileOnly project(':server')
+  // Declared compileOnly rather than api because analytics-api is never
+  // loaded standalone — downstream consumers should declare Calcite themselves.
+  compileOnly "org.apache.calcite:calcite-core:${patchedCalciteVersion}"
+  compileOnly "org.apache.calcite:calcite-linq4j:${patchedCalciteVersion}"
+
+  // Calcite bytecode references annotations from apiguardian (@API) and
+  // checker-framework (@EnsuresNonNullIf). compileOnlyApi propagates to
+  // consumers' compile/javadoc classpath without becoming a runtime dep.
+  compileOnlyApi 'org.apiguardian:apiguardian-api:1.1.2'
+  compileOnlyApi 'org.checkerframework:checker-qual:3.43.0'
+}
diff --git a/sandbox/libs/analytics-framework/src/main/java/org/opensearch/analytics/exec/QueryPlanExecutor.java b/sandbox/libs/analytics-api/src/main/java/org/opensearch/analytics/exec/QueryPlanExecutor.java
similarity index 100%
rename from sandbox/libs/analytics-framework/src/main/java/org/opensearch/analytics/exec/QueryPlanExecutor.java
rename to sandbox/libs/analytics-api/src/main/java/org/opensearch/analytics/exec/QueryPlanExecutor.java
diff --git a/sandbox/libs/analytics-framework/src/main/java/org/opensearch/analytics/exec/package-info.java b/sandbox/libs/analytics-api/src/main/java/org/opensearch/analytics/exec/package-info.java
similarity index 100%
rename from sandbox/libs/analytics-framework/src/main/java/org/opensearch/analytics/exec/package-info.java
rename to sandbox/libs/analytics-api/src/main/java/org/opensearch/analytics/exec/package-info.java
diff --git a/sandbox/plugins/analytics-engine/src/main/java/org/opensearch/analytics/schema/OpenSearchSchemaBuilder.java b/sandbox/libs/analytics-api/src/main/java/org/opensearch/analytics/schema/OpenSearchSchemaBuilder.java
similarity index 100%
rename from sandbox/plugins/analytics-engine/src/main/java/org/opensearch/analytics/schema/OpenSearchSchemaBuilder.java
rename to sandbox/libs/analytics-api/src/main/java/org/opensearch/analytics/schema/OpenSearchSchemaBuilder.java
diff --git a/sandbox/plugins/analytics-engine/src/main/java/org/opensearch/analytics/schema/package-info.java b/sandbox/libs/analytics-api/src/main/java/org/opensearch/analytics/schema/package-info.java
similarity index 100%
rename from sandbox/plugins/analytics-engine/src/main/java/org/opensearch/analytics/schema/package-info.java
rename to sandbox/libs/analytics-api/src/main/java/org/opensearch/analytics/schema/package-info.java
diff --git a/sandbox/libs/analytics-framework/build.gradle b/sandbox/libs/analytics-framework/build.gradle
index f22f55e23cb53..432aa4248e44c 100644
--- a/sandbox/libs/analytics-framework/build.gradle
+++ b/sandbox/libs/analytics-framework/build.gradle
@@ -16,8 +16,6 @@
 // for Janino parent CL); API surface is identical to upstream. The OpenSearch
 // Snapshots repo and the resolutionStrategy.force for this coordinate are
 // declared centrally in sandbox/build.gradle's subprojects block.
-def calciteVersion = "${versions.calcite}-opensearch-${versions.calcite_os_rev}"
-
 java { sourceCompatibility = JavaVersion.toVersion(25); targetCompatibility = JavaVersion.toVersion(25) }
 
 configurations {
@@ -39,9 +37,9 @@ dependencies {
   // interfaces declares its own runtime arrow dep (see analytics-backend-datafusion).
   compileOnly "org.apache.arrow:arrow-vector:${versions.arrow}"
   compileOnly "org.apache.arrow:arrow-memory-core:${versions.arrow}"
-  api "org.apache.calcite:calcite-core:${calciteVersion}"
+  api "org.apache.calcite:calcite-core:${patchedCalciteVersion}"
   // Calcite's expression tree and Enumerable runtime — required by calcite-core API
-  api "org.apache.calcite:calcite-linq4j:${calciteVersion}"
+  api "org.apache.calcite:calcite-linq4j:${patchedCalciteVersion}"
   // Calcite's JDBC abstraction layer — required by calcite-core internals
   runtimeOnly 'org.apache.calcite.avatica:avatica-core:1.27.0'
   // Guava — required by Calcite internally, forbidden on compile classpaths by OpenSearch policy
diff --git a/sandbox/plugins/analytics-engine/build.gradle b/sandbox/plugins/analytics-engine/build.gradle
index 5f7986c74a2cf..0058df4b6eb68 100644
--- a/sandbox/plugins/analytics-engine/build.gradle
+++ b/sandbox/plugins/analytics-engine/build.gradle
@@ -45,8 +45,9 @@ tasks.named('missingJavadoc').configure {
 }
 
 dependencies {
-  // Shared types and SPI interfaces (QueryPlanExecutor, EngineBridge, AnalyticsBackEndPlugin, etc.)
-  // Also provides calcite-core transitively via api.
+  implementation project(':sandbox:libs:analytics-api')
+
+  // Shared SPI interfaces (EngineBridge, AnalyticsBackEndPlugin, etc.) + calcite-core transitively.
   api project(':sandbox:libs:analytics-framework')
 
   // Arrow — provided at runtime by the extended arrow-flight-rpc plugin (same classloader).
diff --git a/sandbox/plugins/dsl-query-executor/build.gradle b/sandbox/plugins/dsl-query-executor/build.gradle
index 539a8e9e16b25..b4ed60fa568b7 100644
--- a/sandbox/plugins/dsl-query-executor/build.gradle
+++ b/sandbox/plugins/dsl-query-executor/build.gradle
@@ -29,6 +29,7 @@ sourceSets.test.compileClasspath += configurations.calciteCompile
 
 dependencies {
   compileOnly project(':server')
+  compileOnly project(':sandbox:libs:analytics-api')
   compileOnly project(':sandbox:libs:analytics-framework')
   compileOnly project(':sandbox:plugins:analytics-engine')
   // TODO: Consume Calcite dependency from Analytics Framework instead of declaring it separately.
diff --git a/sandbox/plugins/test-ppl-frontend/build.gradle b/sandbox/plugins/test-ppl-frontend/build.gradle
index ce908cabd515b..9c2d79c306c9c 100644
--- a/sandbox/plugins/test-ppl-frontend/build.gradle
+++ b/sandbox/plugins/test-ppl-frontend/build.gradle
@@ -52,6 +52,7 @@ sourceSets.test.compileClasspath += configurations.calciteCompile
 
 dependencies {
   // Analytics framework + Calcite provided at runtime by analytics-engine (parent classloader via extendedPlugins)
+  compileOnly project(':sandbox:libs:analytics-api')
   compileOnly project(':sandbox:libs:analytics-framework')
 
   // Guava for compilation — Calcite API exposes guava types