From ac4175c2d9830dbb08a23a25497062c41d266295 Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Fri, 12 May 2023 12:09:34 -0400
Subject: [PATCH 01/15] Experimental IOLocalContextStorage

---
 .../otel4s/java/IOLocalContextStorage.scala   | 36 ++++++++++++++++
 .../otel4s/java/ContextStorageSuite.scala     | 43 +++++++++++++++++++
 2 files changed, 79 insertions(+)
 create mode 100644 java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
 create mode 100644 java/common/src/test/scala/org/typelevel/otel4s/java/ContextStorageSuite.scala

diff --git a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
new file mode 100644
index 000000000..b4cf1f6b2
--- /dev/null
+++ b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
@@ -0,0 +1,36 @@
+package org.typelevel.otel4s.java
+
+import cats.effect.IOLocal
+import cats.effect.LiftIO
+import cats.effect.std.Dispatcher
+import io.opentelemetry.context.Context
+import io.opentelemetry.context.ContextStorage
+import io.opentelemetry.context.Scope
+
+class IOLocalContextStorage[F[_]: LiftIO](
+    dispatcher: Dispatcher[F],
+    ioLocal: IOLocal[Context]
+) extends ContextStorage {
+
+  override def attach(toAttach: Context): Scope =
+    dispatcher.unsafeRunSync(
+      currentOrRoot
+        .flatMap { old =>
+          ioLocal
+            .set(toAttach)
+            .as(new Scope {
+              def close() = dispatcher.unsafeRunSync(ioLocal.set(old).to[F])
+            })
+        }
+        .to[F]
+    )
+
+  override def current(): Context = {
+    dispatcher.unsafeRunSync(currentOrRoot.to[F])
+  }
+
+  private def currentOrRoot = ioLocal.get.map {
+    case null => Context.root()
+    case ctx  => ctx
+  }
+}
diff --git a/java/common/src/test/scala/org/typelevel/otel4s/java/ContextStorageSuite.scala b/java/common/src/test/scala/org/typelevel/otel4s/java/ContextStorageSuite.scala
new file mode 100644
index 000000000..7c71b26e1
--- /dev/null
+++ b/java/common/src/test/scala/org/typelevel/otel4s/java/ContextStorageSuite.scala
@@ -0,0 +1,43 @@
+package org.typelevel.otel4s.java
+
+import cats.effect.IO
+import cats.effect.IOLocal
+import cats.effect.Resource
+import cats.effect.std.Dispatcher
+import io.opentelemetry.context.Context
+import io.opentelemetry.context.ContextKey
+import io.opentelemetry.context.ContextStorage
+import java.util.logging._
+
+object Run extends cats.effect.IOApp.Simple {
+
+  val key = ContextKey.named[String]("test")
+
+  def run =
+    Dispatcher.parallel[IO].use { dispatcher =>
+      for {
+        _ <- IO {
+          val rootLog = Logger.getLogger("")
+          rootLog.setLevel(Level.FINE)
+          rootLog.getHandlers().head.setLevel(Level.FINE)
+        }
+        ioLocal <- IOLocal(null: Context)
+        storage = new IOLocalContextStorage(dispatcher, ioLocal)
+        _ <- IO(ContextStorage.addWrapper(_ => storage))
+        _ <- ioLocal.set(null)
+        _ <- IO.println(ContextStorage.get().getClass)
+        ctx = Context.root()
+        _ <- Resource
+          .make(IO(ctx.`with`(key, "hello").makeCurrent()))(scope =>
+            IO(scope.close())
+          )
+          .surround {
+            for {
+              key <- IO(Context.current())
+              _ <- IO.println(key)
+            } yield ()
+          }
+        _ <- IO(Option(Context.current().get(key))).flatMap(v => IO.println(v))
+      } yield ()
+    }
+}

From 682abb65818c5a353fa1041429737e64d4458cee Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Wed, 17 May 2023 23:04:39 -0400
Subject: [PATCH 02/15] Try typelevel/cats-effect#3636

---
 build.sbt                                     |  5 ++-
 .../main/scala/ContextStorageExample.scala    | 38 ++++++++++++++++
 .../otel4s/java/IOLocalContextStorage.scala   | 34 +++++----------
 .../otel4s/java/ContextStorageSuite.scala     | 43 -------------------
 4 files changed, 52 insertions(+), 68 deletions(-)
 create mode 100644 examples/src/main/scala/ContextStorageExample.scala
 delete mode 100644 java/common/src/test/scala/org/typelevel/otel4s/java/ContextStorageSuite.scala

diff --git a/build.sbt b/build.sbt
index f9c78feb2..f185752e1 100644
--- a/build.sbt
+++ b/build.sbt
@@ -26,7 +26,7 @@ ThisBuild / crossScalaVersions := Seq(Scala213, "3.2.2")
 ThisBuild / scalaVersion := Scala213 // the default Scala
 
 val CatsVersion = "2.9.0"
-val CatsEffectVersion = "3.5.0"
+val CatsEffectVersion = "3.5.0-30-0a69caf"
 val CatsMtlVersion = "1.3.1"
 val FS2Version = "3.6.1"
 val MUnitVersion = "1.0.0-M7"
@@ -154,7 +154,7 @@ lazy val `java-common` = project
   .settings(
     name := "otel4s-java-common",
     libraryDependencies ++= Seq(
-      "org.typelevel" %%% "cats-effect-kernel" % CatsEffectVersion,
+      "org.typelevel" %%% "cats-effect" % CatsEffectVersion,
       "org.typelevel" %%% "cats-mtl" % CatsMtlVersion,
       "io.opentelemetry" % "opentelemetry-sdk" % OpenTelemetryVersion,
       "org.scalameta" %%% "munit" % MUnitVersion % Test
@@ -241,6 +241,7 @@ lazy val examples = project
     ),
     run / fork := true,
     javaOptions += "-Dotel.java.global-autoconfigure.enabled=true",
+    javaOptions += "-Dcats.effect.tracing.dumpLocals",
     envVars ++= Map(
       "OTEL_PROPAGATORS" -> "b3multi",
       "OTEL_SERVICE_NAME" -> "Trace Example"
diff --git a/examples/src/main/scala/ContextStorageExample.scala b/examples/src/main/scala/ContextStorageExample.scala
new file mode 100644
index 000000000..5f786edfc
--- /dev/null
+++ b/examples/src/main/scala/ContextStorageExample.scala
@@ -0,0 +1,38 @@
+import cats.effect.IO
+import cats.effect.IOApp
+import cats.effect.IOLocal
+import cats.effect.Resource
+import cats.effect.unsafe.IOLocals
+import io.opentelemetry.context.Context
+import io.opentelemetry.context.ContextKey
+import io.opentelemetry.context.ContextStorage
+import org.typelevel.otel4s.java.IOLocalContextStorage
+import java.util.logging._
+
+object ContextStorageExample extends IOApp.Simple {
+
+  val key = ContextKey.named[String]("test")
+
+  val printKey =
+    IO(Option(Context.current().get(key))).flatMap(v => IO.println(v))
+
+  def run =
+    for {
+      _ <- IO {
+        val rootLog = Logger.getLogger("")
+        rootLog.setLevel(Level.FINE)
+        rootLog.getHandlers().head.setLevel(Level.FINE)
+      }
+      ioLocal <- IOLocal(null: Context)
+      storage = new IOLocalContextStorage(ioLocal)
+      _ <- IO(ContextStorage.addWrapper(_ => storage))
+      ctx = Context.root()
+      _ = IOLocals.set(ioLocal, Context.root())
+      _ <- Resource
+        .make(IO(ctx.`with`(key, "hello").makeCurrent()))(scope =>
+          IO(scope.close())
+        )
+        .surround(printKey)
+      _ <- printKey
+    } yield ()
+}
diff --git a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
index b4cf1f6b2..77adcf39a 100644
--- a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
+++ b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
@@ -1,36 +1,24 @@
 package org.typelevel.otel4s.java
 
 import cats.effect.IOLocal
-import cats.effect.LiftIO
-import cats.effect.std.Dispatcher
+import cats.effect.unsafe.IOLocals
 import io.opentelemetry.context.Context
 import io.opentelemetry.context.ContextStorage
 import io.opentelemetry.context.Scope
 
-class IOLocalContextStorage[F[_]: LiftIO](
-    dispatcher: Dispatcher[F],
+class IOLocalContextStorage(
     ioLocal: IOLocal[Context]
 ) extends ContextStorage {
 
-  override def attach(toAttach: Context): Scope =
-    dispatcher.unsafeRunSync(
-      currentOrRoot
-        .flatMap { old =>
-          ioLocal
-            .set(toAttach)
-            .as(new Scope {
-              def close() = dispatcher.unsafeRunSync(ioLocal.set(old).to[F])
-            })
-        }
-        .to[F]
-    )
-
-  override def current(): Context = {
-    dispatcher.unsafeRunSync(currentOrRoot.to[F])
+  override def attach(toAttach: Context): Scope = {
+    val previous = current()
+    IOLocals.set(ioLocal, toAttach)
+    new Scope {
+      def close() = IOLocals.set(ioLocal, previous)
+    }
   }
 
-  private def currentOrRoot = ioLocal.get.map {
-    case null => Context.root()
-    case ctx  => ctx
-  }
+  override def current(): Context =
+    IOLocals.get(ioLocal)
+
 }
diff --git a/java/common/src/test/scala/org/typelevel/otel4s/java/ContextStorageSuite.scala b/java/common/src/test/scala/org/typelevel/otel4s/java/ContextStorageSuite.scala
deleted file mode 100644
index 7c71b26e1..000000000
--- a/java/common/src/test/scala/org/typelevel/otel4s/java/ContextStorageSuite.scala
+++ /dev/null
@@ -1,43 +0,0 @@
-package org.typelevel.otel4s.java
-
-import cats.effect.IO
-import cats.effect.IOLocal
-import cats.effect.Resource
-import cats.effect.std.Dispatcher
-import io.opentelemetry.context.Context
-import io.opentelemetry.context.ContextKey
-import io.opentelemetry.context.ContextStorage
-import java.util.logging._
-
-object Run extends cats.effect.IOApp.Simple {
-
-  val key = ContextKey.named[String]("test")
-
-  def run =
-    Dispatcher.parallel[IO].use { dispatcher =>
-      for {
-        _ <- IO {
-          val rootLog = Logger.getLogger("")
-          rootLog.setLevel(Level.FINE)
-          rootLog.getHandlers().head.setLevel(Level.FINE)
-        }
-        ioLocal <- IOLocal(null: Context)
-        storage = new IOLocalContextStorage(dispatcher, ioLocal)
-        _ <- IO(ContextStorage.addWrapper(_ => storage))
-        _ <- ioLocal.set(null)
-        _ <- IO.println(ContextStorage.get().getClass)
-        ctx = Context.root()
-        _ <- Resource
-          .make(IO(ctx.`with`(key, "hello").makeCurrent()))(scope =>
-            IO(scope.close())
-          )
-          .surround {
-            for {
-              key <- IO(Context.current())
-              _ <- IO.println(key)
-            } yield ()
-          }
-        _ <- IO(Option(Context.current().get(key))).flatMap(v => IO.println(v))
-      } yield ()
-    }
-}

From 5f460eec0f5c88f5ba552ef5a4b6ab19d25b8b24 Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Thu, 18 May 2023 17:45:21 -0400
Subject: [PATCH 03/15] Apply suggestions from code review

Co-authored-by: Arman Bilge <armanbilge@gmail.com>
---
 build.sbt                                           | 2 +-
 examples/src/main/scala/ContextStorageExample.scala | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/build.sbt b/build.sbt
index f185752e1..b6ce8cbb6 100644
--- a/build.sbt
+++ b/build.sbt
@@ -241,7 +241,7 @@ lazy val examples = project
     ),
     run / fork := true,
     javaOptions += "-Dotel.java.global-autoconfigure.enabled=true",
-    javaOptions += "-Dcats.effect.tracing.dumpLocals",
+    javaOptions += "-Dcats.effect.tracing.dumpLocals=true",
     envVars ++= Map(
       "OTEL_PROPAGATORS" -> "b3multi",
       "OTEL_SERVICE_NAME" -> "Trace Example"
diff --git a/examples/src/main/scala/ContextStorageExample.scala b/examples/src/main/scala/ContextStorageExample.scala
index 5f786edfc..8967b49c8 100644
--- a/examples/src/main/scala/ContextStorageExample.scala
+++ b/examples/src/main/scala/ContextStorageExample.scala
@@ -27,7 +27,7 @@ object ContextStorageExample extends IOApp.Simple {
       storage = new IOLocalContextStorage(ioLocal)
       _ <- IO(ContextStorage.addWrapper(_ => storage))
       ctx = Context.root()
-      _ = IOLocals.set(ioLocal, Context.root())
+      _ <- ioLocal.set(Context.root())
       _ <- Resource
         .make(IO(ctx.`with`(key, "hello").makeCurrent()))(scope =>
           IO(scope.close())

From e522ac8117230cc909c7b24d51c984f29557d811 Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Thu, 18 May 2023 17:46:48 -0400
Subject: [PATCH 04/15] Get latest cats-effect branch

---
 build.sbt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/build.sbt b/build.sbt
index b6ce8cbb6..f3222e416 100644
--- a/build.sbt
+++ b/build.sbt
@@ -26,7 +26,7 @@ ThisBuild / crossScalaVersions := Seq(Scala213, "3.2.2")
 ThisBuild / scalaVersion := Scala213 // the default Scala
 
 val CatsVersion = "2.9.0"
-val CatsEffectVersion = "3.5.0-30-0a69caf"
+val CatsEffectVersion = "3.5.0-31-2775064"
 val CatsMtlVersion = "1.3.1"
 val FS2Version = "3.6.1"
 val MUnitVersion = "1.0.0-M7"

From d9a1079206b82ba6f8c4ae8a8072cbfb2776d49c Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Thu, 18 May 2023 17:49:17 -0400
Subject: [PATCH 05/15] Fine, have your headers

---
 .../src/main/scala/ContextStorageExample.scala   | 16 ++++++++++++++++
 .../otel4s/java/IOLocalContextStorage.scala      | 16 ++++++++++++++++
 2 files changed, 32 insertions(+)

diff --git a/examples/src/main/scala/ContextStorageExample.scala b/examples/src/main/scala/ContextStorageExample.scala
index 8967b49c8..f141ed0f0 100644
--- a/examples/src/main/scala/ContextStorageExample.scala
+++ b/examples/src/main/scala/ContextStorageExample.scala
@@ -1,3 +1,19 @@
+/*
+ * Copyright 2022 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 import cats.effect.IO
 import cats.effect.IOApp
 import cats.effect.IOLocal
diff --git a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
index 77adcf39a..a2c46f9cf 100644
--- a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
+++ b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
@@ -1,3 +1,19 @@
+/*
+ * Copyright 2022 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package org.typelevel.otel4s.java
 
 import cats.effect.IOLocal

From c4410ab7a53c98c7fb53e42f9c346eab2f44398b Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Thu, 18 May 2023 23:33:51 -0400
Subject: [PATCH 06/15] Unused import

---
 examples/src/main/scala/ContextStorageExample.scala | 1 -
 1 file changed, 1 deletion(-)

diff --git a/examples/src/main/scala/ContextStorageExample.scala b/examples/src/main/scala/ContextStorageExample.scala
index f141ed0f0..3e6ab0ff9 100644
--- a/examples/src/main/scala/ContextStorageExample.scala
+++ b/examples/src/main/scala/ContextStorageExample.scala
@@ -18,7 +18,6 @@ import cats.effect.IO
 import cats.effect.IOApp
 import cats.effect.IOLocal
 import cats.effect.Resource
-import cats.effect.unsafe.IOLocals
 import io.opentelemetry.context.Context
 import io.opentelemetry.context.ContextKey
 import io.opentelemetry.context.ContextStorage

From 6b542aaeecae0e7fb49af7fbe303c933d96c774d Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Fri, 19 May 2023 00:09:01 -0400
Subject: [PATCH 07/15] Get testkit out of main dependenecies

---
 build.sbt | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/build.sbt b/build.sbt
index f3222e416..2f79c0f78 100644
--- a/build.sbt
+++ b/build.sbt
@@ -150,7 +150,7 @@ lazy val testkit = crossProject(JVMPlatform)
 lazy val `java-common` = project
   .in(file("java/common"))
   .enablePlugins(BuildInfoPlugin)
-  .dependsOn(`core-common`.jvm, `testkit-common`.jvm)
+  .dependsOn(`core-common`.jvm, `testkit-common`.jvm % Test)
   .settings(
     name := "otel4s-java-common",
     libraryDependencies ++= Seq(
@@ -168,7 +168,7 @@ lazy val `java-common` = project
 
 lazy val `java-metrics` = project
   .in(file("java/metrics"))
-  .dependsOn(`java-common`, `core-metrics`.jvm, `testkit-metrics`.jvm)
+  .dependsOn(`java-common`, `core-metrics`.jvm, `testkit-metrics`.jvm % Test)
   .settings(munitDependencies)
   .settings(
     name := "otel4s-java-metrics",
@@ -222,7 +222,7 @@ lazy val benchmarks = project
   .enablePlugins(NoPublishPlugin)
   .enablePlugins(JmhPlugin)
   .in(file("benchmarks"))
-  .dependsOn(core.jvm, java)
+  .dependsOn(core.jvm, java, `testkit-metrics`.jvm)
   .settings(
     name := "otel4s-benchmarks"
   )

From b6a75a010de68e1218d2b03fa513e9e7349eb2f3 Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Fri, 19 May 2023 00:09:22 -0400
Subject: [PATCH 08/15] Attmept at a ContextStorageProvider SPI

---
 .../main/scala/ContextStorageExample.scala    | 13 +++----
 ...entelemetry.context.ContextStorageProvider |  1 +
 .../otel4s/java/IOLocalContextStorage.scala   |  9 ++---
 .../java/IOLocalContextStorageProvider.scala  | 36 +++++++++++++++++++
 4 files changed, 47 insertions(+), 12 deletions(-)
 create mode 100644 java/common/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider
 create mode 100644 java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala

diff --git a/examples/src/main/scala/ContextStorageExample.scala b/examples/src/main/scala/ContextStorageExample.scala
index 3e6ab0ff9..5c905dca4 100644
--- a/examples/src/main/scala/ContextStorageExample.scala
+++ b/examples/src/main/scala/ContextStorageExample.scala
@@ -16,12 +16,12 @@
 
 import cats.effect.IO
 import cats.effect.IOApp
-import cats.effect.IOLocal
 import cats.effect.Resource
 import io.opentelemetry.context.Context
 import io.opentelemetry.context.ContextKey
 import io.opentelemetry.context.ContextStorage
-import org.typelevel.otel4s.java.IOLocalContextStorage
+import org.typelevel.otel4s.java.IOLocalContextStorageProvider
+
 import java.util.logging._
 
 object ContextStorageExample extends IOApp.Simple {
@@ -38,13 +38,10 @@ object ContextStorageExample extends IOApp.Simple {
         rootLog.setLevel(Level.FINE)
         rootLog.getHandlers().head.setLevel(Level.FINE)
       }
-      ioLocal <- IOLocal(null: Context)
-      storage = new IOLocalContextStorage(ioLocal)
-      _ <- IO(ContextStorage.addWrapper(_ => storage))
-      ctx = Context.root()
-      _ <- ioLocal.set(Context.root())
+      _ <- IOLocalContextStorageProvider.localContext.set(Context.root())
+      _ <- IO.println(ContextStorage.get.getClass())
       _ <- Resource
-        .make(IO(ctx.`with`(key, "hello").makeCurrent()))(scope =>
+        .make(IO(Context.root().`with`(key, "hello").makeCurrent()))(scope =>
           IO(scope.close())
         )
         .surround(printKey)
diff --git a/java/common/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider b/java/common/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider
new file mode 100644
index 000000000..aeea4e705
--- /dev/null
+++ b/java/common/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider
@@ -0,0 +1 @@
+org.typelevel.otel4s.java.IOLocalContextStorageProvider
\ No newline at end of file
diff --git a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
index a2c46f9cf..0096ae32a 100644
--- a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
+++ b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
@@ -16,6 +16,7 @@
 
 package org.typelevel.otel4s.java
 
+import cats.Eval
 import cats.effect.IOLocal
 import cats.effect.unsafe.IOLocals
 import io.opentelemetry.context.Context
@@ -23,18 +24,18 @@ import io.opentelemetry.context.ContextStorage
 import io.opentelemetry.context.Scope
 
 class IOLocalContextStorage(
-    ioLocal: IOLocal[Context]
+    ioLocal: Eval[IOLocal[Context]]
 ) extends ContextStorage {
 
   override def attach(toAttach: Context): Scope = {
     val previous = current()
-    IOLocals.set(ioLocal, toAttach)
+    IOLocals.set(ioLocal.value, toAttach)
     new Scope {
-      def close() = IOLocals.set(ioLocal, previous)
+      def close() = IOLocals.set(ioLocal.value, previous)
     }
   }
 
   override def current(): Context =
-    IOLocals.get(ioLocal)
+    IOLocals.get(ioLocal.value)
 
 }
diff --git a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
new file mode 100644
index 000000000..6d1ecf678
--- /dev/null
+++ b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
@@ -0,0 +1,36 @@
+/*
+ * Copyright 2022 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.otel4s.java
+
+import cats.Eval
+import cats.effect.IOLocal
+import cats.effect.unsafe.implicits.global
+import io.opentelemetry.context.Context
+import io.opentelemetry.context.ContextStorage
+import io.opentelemetry.context.ContextStorageProvider
+
+object IOLocalContextStorageProvider {
+  val localContext: IOLocal[Context] =
+    IOLocal[Context](Context.root()).unsafeRunSync()
+}
+
+class IOLocalContextStorageProvider extends ContextStorageProvider {
+  def get(): ContextStorage =
+    new IOLocalContextStorage(
+      Eval.later(IOLocalContextStorageProvider.localContext)
+    )
+}

From 978ccefc2a6a10a681a22cb57f35694bc5eaba6c Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Fri, 19 May 2023 09:20:37 -0400
Subject: [PATCH 09/15] Use syncStep to initialize the local context

---
 .../java/IOLocalContextStorageProvider.scala       | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
index 6d1ecf678..062b2e116 100644
--- a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
+++ b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
@@ -18,14 +18,24 @@ package org.typelevel.otel4s.java
 
 import cats.Eval
 import cats.effect.IOLocal
-import cats.effect.unsafe.implicits.global
+import cats.effect.SyncIO
+import cats.syntax.all._
 import io.opentelemetry.context.Context
 import io.opentelemetry.context.ContextStorage
 import io.opentelemetry.context.ContextStorageProvider
 
 object IOLocalContextStorageProvider {
   val localContext: IOLocal[Context] =
-    IOLocal[Context](Context.root()).unsafeRunSync()
+    IOLocal[Context](Context.root())
+      .syncStep(100)
+      .flatMap(
+        _.leftMap(_ =>
+          new Error(
+            "Failed to initialize the local context of the IOLocalContextStorageProvider."
+          )
+        ).liftTo[SyncIO]
+      )
+      .unsafeRunSync()
 }
 
 class IOLocalContextStorageProvider extends ContextStorageProvider {

From 99137043b59ea1febca24f2058b0344481b9fde1 Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Mon, 22 May 2023 12:02:25 -0400
Subject: [PATCH 10/15] Update Cats Effect snapshot

---
 build.sbt | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/build.sbt b/build.sbt
index 2f79c0f78..560756117 100644
--- a/build.sbt
+++ b/build.sbt
@@ -26,7 +26,7 @@ ThisBuild / crossScalaVersions := Seq(Scala213, "3.2.2")
 ThisBuild / scalaVersion := Scala213 // the default Scala
 
 val CatsVersion = "2.9.0"
-val CatsEffectVersion = "3.5.0-31-2775064"
+val CatsEffectVersion = "3.5.0-34-2cf72a5"
 val CatsMtlVersion = "1.3.1"
 val FS2Version = "3.6.1"
 val MUnitVersion = "1.0.0-M7"

From b6c2b0ff31727e530b3f4675376964f12b7e04a3 Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Mon, 22 May 2023 12:03:20 -0400
Subject: [PATCH 11/15] Remove direct reference to
 IOLocalContextStorageProvider

---
 examples/src/main/scala/ContextStorageExample.scala | 2 --
 1 file changed, 2 deletions(-)

diff --git a/examples/src/main/scala/ContextStorageExample.scala b/examples/src/main/scala/ContextStorageExample.scala
index 5c905dca4..de155209f 100644
--- a/examples/src/main/scala/ContextStorageExample.scala
+++ b/examples/src/main/scala/ContextStorageExample.scala
@@ -20,7 +20,6 @@ import cats.effect.Resource
 import io.opentelemetry.context.Context
 import io.opentelemetry.context.ContextKey
 import io.opentelemetry.context.ContextStorage
-import org.typelevel.otel4s.java.IOLocalContextStorageProvider
 
 import java.util.logging._
 
@@ -38,7 +37,6 @@ object ContextStorageExample extends IOApp.Simple {
         rootLog.setLevel(Level.FINE)
         rootLog.getHandlers().head.setLevel(Level.FINE)
       }
-      _ <- IOLocalContextStorageProvider.localContext.set(Context.root())
       _ <- IO.println(ContextStorage.get.getClass())
       _ <- Resource
         .make(IO(Context.root().`with`(key, "hello").makeCurrent()))(scope =>

From 8c311369895f7e674444418b76ab23ada46d0cb0 Mon Sep 17 00:00:00 2001
From: "Ross A. Baker" <ross@rossabaker.com>
Date: Mon, 22 May 2023 23:29:22 -0400
Subject: [PATCH 12/15] Unbox IOLocal

Co-authored-by: Arman Bilge <armanbilge@gmail.com>
---
 .../org/typelevel/otel4s/java/IOLocalContextStorage.scala     | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
index 0096ae32a..ea346bf7d 100644
--- a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
+++ b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
@@ -24,9 +24,9 @@ import io.opentelemetry.context.ContextStorage
 import io.opentelemetry.context.Scope
 
 class IOLocalContextStorage(
-    ioLocal: Eval[IOLocal[Context]]
+    _ioLocal: => IOLocal[Context]
 ) extends ContextStorage {
-
+  private[this] lazy val ioLocal = _ioLocal
   override def attach(toAttach: Context): Scope = {
     val previous = current()
     IOLocals.set(ioLocal.value, toAttach)

From fe7259e6dc3f2af3019912b8d786ba484b052692 Mon Sep 17 00:00:00 2001
From: Arman Bilge <armanbilge@gmail.com>
Date: Wed, 28 Jun 2023 22:28:32 +0000
Subject: [PATCH 13/15] Fix compile, update to CE snapshot

---
 build.sbt                                                  | 4 ++--
 .../org/typelevel/otel4s/java/IOLocalContextStorage.scala  | 7 +++----
 .../otel4s/java/IOLocalContextStorageProvider.scala        | 5 +----
 3 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/build.sbt b/build.sbt
index c4954329c..07ef6dec3 100644
--- a/build.sbt
+++ b/build.sbt
@@ -26,7 +26,7 @@ ThisBuild / crossScalaVersions := Seq(Scala213, "3.3.0")
 ThisBuild / scalaVersion := Scala213 // the default Scala
 
 val CatsVersion = "2.9.0"
-val CatsEffectVersion = "3.5.0-34-2cf72a5"
+val CatsEffectVersion = "3.6-02a43a6"
 val CatsMtlVersion = "1.3.1"
 val DisciplineMUnitVersion = "2.0.0-M3"
 val FS2Version = "3.7.0"
@@ -265,7 +265,7 @@ lazy val examples = project
     ),
     run / fork := true,
     javaOptions += "-Dotel.java.global-autoconfigure.enabled=true",
-    javaOptions += "-Dcats.effect.tracing.dumpLocals=true",
+    javaOptions += "-Dcats.effect.ioLocalPropagation=true",
     envVars ++= Map(
       "OTEL_PROPAGATORS" -> "b3multi",
       "OTEL_SERVICE_NAME" -> "Trace Example"
diff --git a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
index ea346bf7d..e18a80b38 100644
--- a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
+++ b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
@@ -16,7 +16,6 @@
 
 package org.typelevel.otel4s.java
 
-import cats.Eval
 import cats.effect.IOLocal
 import cats.effect.unsafe.IOLocals
 import io.opentelemetry.context.Context
@@ -29,13 +28,13 @@ class IOLocalContextStorage(
   private[this] lazy val ioLocal = _ioLocal
   override def attach(toAttach: Context): Scope = {
     val previous = current()
-    IOLocals.set(ioLocal.value, toAttach)
+    IOLocals.set(ioLocal, toAttach)
     new Scope {
-      def close() = IOLocals.set(ioLocal.value, previous)
+      def close() = IOLocals.set(ioLocal, previous)
     }
   }
 
   override def current(): Context =
-    IOLocals.get(ioLocal.value)
+    IOLocals.get(ioLocal)
 
 }
diff --git a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
index 062b2e116..d328674d2 100644
--- a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
+++ b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
@@ -16,7 +16,6 @@
 
 package org.typelevel.otel4s.java
 
-import cats.Eval
 import cats.effect.IOLocal
 import cats.effect.SyncIO
 import cats.syntax.all._
@@ -40,7 +39,5 @@ object IOLocalContextStorageProvider {
 
 class IOLocalContextStorageProvider extends ContextStorageProvider {
   def get(): ContextStorage =
-    new IOLocalContextStorage(
-      Eval.later(IOLocalContextStorageProvider.localContext)
-    )
+    new IOLocalContextStorage(IOLocalContextStorageProvider.localContext)
 }

From e60f79316b3afa46378b83cc15e4d933439f494f Mon Sep 17 00:00:00 2001
From: Marissa <dev@princess.lgbt>
Date: Thu, 31 Aug 2023 06:17:51 -0400
Subject: [PATCH 14/15] Finish implementing `IOLocalContextStorage`

Finish implementing `IOLocalContextStorage` and
`IOLocalContextStorageProvider` for sharing context modifications
between Java and Scala instrumentation.
---
 .github/workflows/ci.yml                      |   4 +-
 build.sbt                                     |  21 +-
 ...entelemetry.context.ContextStorageProvider |   1 -
 .../otel4s/java/IOLocalContextStorage.scala   |  40 ---
 .../otel4s/java/context/Context.scala         |   2 +-
 ...entelemetry.context.ContextStorageProvider |   1 +
 .../otel4s/java/IOLocalContextStorage.scala   |  92 ++++++
 .../java/IOLocalContextStorageProvider.scala  |   9 +-
 .../java/IOLocalContextStorageSuite.scala     | 264 ++++++++++++++++++
 9 files changed, 385 insertions(+), 49 deletions(-)
 delete mode 100644 java/common/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider
 delete mode 100644 java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
 create mode 100644 java/context-storage/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider
 create mode 100644 java/context-storage/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
 rename java/{common => context-storage}/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala (81%)
 create mode 100644 java/context-storage/src/test/scala/org/typelevel/otel4s/java/IOLocalContextStorageSuite.scala

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 14b53176b..4113c48f9 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -84,11 +84,11 @@ jobs:
 
       - name: Make target directories
         if: github.event_name != 'pull_request' && (startsWith(github.ref, 'refs/tags/v') || github.ref == 'refs/heads/main')
-        run: mkdir -p testkit/metrics/jvm/target java/metrics/target testkit/common/jvm/target core/trace/.js/target semconv/.jvm/target core/common/.jvm/target java/trace/target unidocs/target core/metrics/.native/target core/all/.native/target core/metrics/.jvm/target core/all/.js/target java/all/target java/common/target core/metrics/.js/target core/all/.jvm/target core/trace/.native/target semconv/.js/target core/trace/.jvm/target core/common/.native/target core/common/.js/target semconv/.native/target testkit/all/jvm/target project/target
+        run: mkdir -p testkit/metrics/jvm/target java/metrics/target testkit/common/jvm/target core/trace/.js/target semconv/.jvm/target core/common/.jvm/target java/trace/target unidocs/target core/metrics/.native/target core/all/.native/target core/metrics/.jvm/target java/context-storage/target core/all/.js/target java/all/target java/common/target core/metrics/.js/target core/all/.jvm/target core/trace/.native/target semconv/.js/target core/trace/.jvm/target core/common/.native/target core/common/.js/target semconv/.native/target testkit/all/jvm/target project/target
 
       - name: Compress target directories
         if: github.event_name != 'pull_request' && (startsWith(github.ref, 'refs/tags/v') || github.ref == 'refs/heads/main')
-        run: tar cf targets.tar testkit/metrics/jvm/target java/metrics/target testkit/common/jvm/target core/trace/.js/target semconv/.jvm/target core/common/.jvm/target java/trace/target unidocs/target core/metrics/.native/target core/all/.native/target core/metrics/.jvm/target core/all/.js/target java/all/target java/common/target core/metrics/.js/target core/all/.jvm/target core/trace/.native/target semconv/.js/target core/trace/.jvm/target core/common/.native/target core/common/.js/target semconv/.native/target testkit/all/jvm/target project/target
+        run: tar cf targets.tar testkit/metrics/jvm/target java/metrics/target testkit/common/jvm/target core/trace/.js/target semconv/.jvm/target core/common/.jvm/target java/trace/target unidocs/target core/metrics/.native/target core/all/.native/target core/metrics/.jvm/target java/context-storage/target core/all/.js/target java/all/target java/common/target core/metrics/.js/target core/all/.jvm/target core/trace/.native/target semconv/.js/target core/trace/.jvm/target core/common/.native/target core/common/.js/target semconv/.native/target testkit/all/jvm/target project/target
 
       - name: Upload target directories
         if: github.event_name != 'pull_request' && (startsWith(github.ref, 'refs/tags/v') || github.ref == 'refs/heads/main')
diff --git a/build.sbt b/build.sbt
index 547448ab7..a08b8887a 100644
--- a/build.sbt
+++ b/build.sbt
@@ -67,6 +67,7 @@ lazy val root = tlCrossRootProject
     `testkit-metrics`,
     testkit,
     `java-common`,
+    `java-context-storage`,
     `java-metrics`,
     `java-trace`,
     java,
@@ -288,9 +289,27 @@ lazy val `java-trace` = project
   )
   .settings(scalafixSettings)
 
+lazy val `java-context-storage` = project
+  .in(file("java/context-storage"))
+  .dependsOn(`java-common`)
+  .settings(munitDependencies)
+  .settings(
+    name := "otel4s-java-context-storage",
+    libraryDependencies ++= Seq(
+      "org.typelevel" %%% "cats-effect" % CatsEffectVersion,
+      "org.typelevel" %%% "cats-effect-testkit" % CatsEffectVersion % Test,
+    ),
+    Test / javaOptions ++= Seq(
+      "-Dotel.java.global-autoconfigure.enabled=true",
+      "-Dcats.effect.ioLocalPropagation=true",
+    ),
+    Test / fork := true,
+  )
+  .settings(scalafixSettings)
+
 lazy val java = project
   .in(file("java/all"))
-  .dependsOn(core.jvm, `java-metrics`, `java-trace`)
+  .dependsOn(core.jvm, `java-metrics`, `java-trace`, `java-context-storage`)
   .settings(
     name := "otel4s-java",
     libraryDependencies ++= Seq(
diff --git a/java/common/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider b/java/common/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider
deleted file mode 100644
index aeea4e705..000000000
--- a/java/common/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider
+++ /dev/null
@@ -1 +0,0 @@
-org.typelevel.otel4s.java.IOLocalContextStorageProvider
\ No newline at end of file
diff --git a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala b/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
deleted file mode 100644
index e18a80b38..000000000
--- a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
+++ /dev/null
@@ -1,40 +0,0 @@
-/*
- * Copyright 2022 Typelevel
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *     http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.typelevel.otel4s.java
-
-import cats.effect.IOLocal
-import cats.effect.unsafe.IOLocals
-import io.opentelemetry.context.Context
-import io.opentelemetry.context.ContextStorage
-import io.opentelemetry.context.Scope
-
-class IOLocalContextStorage(
-    _ioLocal: => IOLocal[Context]
-) extends ContextStorage {
-  private[this] lazy val ioLocal = _ioLocal
-  override def attach(toAttach: Context): Scope = {
-    val previous = current()
-    IOLocals.set(ioLocal, toAttach)
-    new Scope {
-      def close() = IOLocals.set(ioLocal, previous)
-    }
-  }
-
-  override def current(): Context =
-    IOLocals.get(ioLocal)
-
-}
diff --git a/java/common/src/main/scala/org/typelevel/otel4s/java/context/Context.scala b/java/common/src/main/scala/org/typelevel/otel4s/java/context/Context.scala
index 6c224b1f2..d3996fb76 100644
--- a/java/common/src/main/scala/org/typelevel/otel4s/java/context/Context.scala
+++ b/java/common/src/main/scala/org/typelevel/otel4s/java/context/Context.scala
@@ -95,7 +95,7 @@ object Context {
   }
 
   /** The root [[`Context`]], from which all other contexts are derived. */
-  val root: Context = wrap(JContext.root())
+  lazy val root: Context = wrap(JContext.root())
 
   implicit object Contextual extends context.Contextual[Context] {
     type Key[A] = Context.Key[A]
diff --git a/java/context-storage/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider b/java/context-storage/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider
new file mode 100644
index 000000000..6b56f5271
--- /dev/null
+++ b/java/context-storage/src/main/resources/META-INF/services/io.opentelemetry.context.ContextStorageProvider
@@ -0,0 +1 @@
+org.typelevel.otel4s.java.IOLocalContextStorageProvider
diff --git a/java/context-storage/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala b/java/context-storage/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
new file mode 100644
index 000000000..ed767622e
--- /dev/null
+++ b/java/context-storage/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
@@ -0,0 +1,92 @@
+/*
+ * Copyright 2022 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.otel4s.java
+
+import cats.effect.IOLocal
+import cats.effect.LiftIO
+import cats.effect.MonadCancelThrow
+import cats.effect.unsafe.IOLocals
+import io.opentelemetry.context.{Context => JContext}
+import io.opentelemetry.context.ContextStorage
+import io.opentelemetry.context.Scope
+import org.typelevel.otel4s.java.context.Context
+import org.typelevel.otel4s.java.context.LocalContext
+import org.typelevel.otel4s.java.instances._
+
+/** A `ContextStorage` backed by an [[cats.effect.IOLocal `IOLocal`]] of a
+  * [[`Context`]] that also provides [[cats.mtl.Local `Local`]] instances that
+  * reflect the state of the backing `IOLocal`. Usage of `Local` and
+  * `ContextStorage` methods will be consistent and stay in sync as long as
+  * effects are threaded properly.
+  */
+class IOLocalContextStorage(_ioLocal: () => IOLocal[Context])
+    extends ContextStorage {
+  private[this] implicit lazy val ioLocal: IOLocal[Context] = _ioLocal()
+
+  @inline private[this] def unsafeCurrent: Context =
+    IOLocals.get(ioLocal)
+
+  override def attach(toAttach: JContext): Scope = {
+    val previous = unsafeCurrent
+    IOLocals.set(ioLocal, Context.wrap(toAttach))
+    () => IOLocals.set(ioLocal, previous)
+  }
+
+  override def current(): JContext =
+    unsafeCurrent.underlying
+
+  /** @return
+    *   a [[cats.mtl.Local `Local`]] of a [[`Context`]] that reflects the state
+    *   of the backing `IOLocal`
+    */
+  def local[F[_]: MonadCancelThrow: LiftIO]: LocalContext[F] = implicitly
+}
+
+object IOLocalContextStorage {
+
+  /** Returns a [[cats.mtl.Local `Local`]] of a [[`Context`]] if an
+    * [[`IOLocalContextStorage`]] is configured to be used as the
+    * `ContextStorage` for the Java otel library.
+    *
+    * Raises an exception if an [[`IOLocalContextStorage`]] is __not__
+    * configured to be used as the `ContextStorage` for the Java otel library,
+    * or if [[cats.effect.IOLocal `IOLocal`]] propagation is not enabled.
+    */
+  def providedLocal[F[_]: LiftIO](implicit
+      F: MonadCancelThrow[F]
+  ): F[LocalContext[F]] =
+    ContextStorage.get() match {
+      case storage: IOLocalContextStorage =>
+        // TODO: check `IOLocals.arePropagating` instead once our dependencies
+        //       are updated
+        if (java.lang.Boolean.getBoolean("cats.effect.ioLocalPropagation")) {
+          F.pure(storage.local)
+        } else {
+          F.raiseError(
+            new IllegalStateException(
+              "IOLocal propagation must be enabled with: -Dcats.effect.ioLocalPropagation=true"
+            )
+          )
+        }
+      case _ =>
+        F.raiseError(
+          new IllegalStateException(
+            "IOLocalContextStorage is not configured for use as the ContextStorageProvider"
+          )
+        )
+    }
+}
diff --git a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala b/java/context-storage/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
similarity index 81%
rename from java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
rename to java/context-storage/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
index d328674d2..0c578051b 100644
--- a/java/common/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
+++ b/java/context-storage/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorageProvider.scala
@@ -19,13 +19,13 @@ package org.typelevel.otel4s.java
 import cats.effect.IOLocal
 import cats.effect.SyncIO
 import cats.syntax.all._
-import io.opentelemetry.context.Context
 import io.opentelemetry.context.ContextStorage
 import io.opentelemetry.context.ContextStorageProvider
+import org.typelevel.otel4s.java.context.Context
 
 object IOLocalContextStorageProvider {
-  val localContext: IOLocal[Context] =
-    IOLocal[Context](Context.root())
+  private lazy val localContext: IOLocal[Context] =
+    IOLocal[Context](Context.root)
       .syncStep(100)
       .flatMap(
         _.leftMap(_ =>
@@ -37,7 +37,8 @@ object IOLocalContextStorageProvider {
       .unsafeRunSync()
 }
 
+/** SPI implementation for [[`IOLocalContextStorage`]]. */
 class IOLocalContextStorageProvider extends ContextStorageProvider {
   def get(): ContextStorage =
-    new IOLocalContextStorage(IOLocalContextStorageProvider.localContext)
+    new IOLocalContextStorage(() => IOLocalContextStorageProvider.localContext)
 }
diff --git a/java/context-storage/src/test/scala/org/typelevel/otel4s/java/IOLocalContextStorageSuite.scala b/java/context-storage/src/test/scala/org/typelevel/otel4s/java/IOLocalContextStorageSuite.scala
new file mode 100644
index 000000000..b7611887e
--- /dev/null
+++ b/java/context-storage/src/test/scala/org/typelevel/otel4s/java/IOLocalContextStorageSuite.scala
@@ -0,0 +1,264 @@
+/*
+ * Copyright 2022 Typelevel
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.typelevel.otel4s.java
+
+import cats.effect.IO
+import cats.effect.SyncIO
+import io.opentelemetry.context.{Context => JContext}
+import io.opentelemetry.context.ContextStorage
+import munit.CatsEffectSuite
+import munit.Location
+import org.typelevel.otel4s.context.Key
+import org.typelevel.otel4s.java.context.Context
+import org.typelevel.otel4s.java.context.LocalContext
+
+import scala.util.Using
+
+class IOLocalContextStorageSuite extends CatsEffectSuite {
+  import IOLocalContextStorageSuite._
+
+  private val localF: IO[LocalContext[IO]] =
+    IOLocalContextStorage.providedLocal
+
+  private def sCurrent[F[_]](implicit L: LocalContext[F]): F[Context] =
+    L.ask[Context]
+  private def jCurrent: JContext = JContext.current()
+
+  private def usingModifiedCtx[A](f: JContext => JContext)(body: => A): A =
+    Using.resource(f(jCurrent).makeCurrent())(_ => body)
+
+  private def localTest(
+      name: String
+  )(body: LocalContext[IO] => IO[Any])(implicit loc: Location): Unit =
+    test(name) {
+      for {
+        local <- localF
+        _ <- body(local)
+      } yield ()
+    }
+
+  // if this fails, the rest will almost certainly fail,
+  // and will be meaningless regardless
+  localTest("correctly configured") { implicit L =>
+    for {
+      sCtx <- sCurrent
+      jCtx <- IO(jCurrent)
+    } yield {
+      // correct ContextStorage is configured
+      assertEquals(
+        ContextStorage.get().getClass: Any,
+        classOf[IOLocalContextStorage]: Any
+      )
+
+      // current is root
+      assertEquals(JContext.root(), Context.root.underlying)
+      assertEquals(jCtx, sCtx.underlying)
+      assertEquals(sCtx, Context.root)
+      assertEquals(jCtx, JContext.root())
+
+      // root is empty
+      assertEquals(sCtx.get(key1), None)
+      assertEquals(sCtx.get(key2), None)
+      assertEquals(Option(jCtx.get(key1)), None)
+      assertEquals(Option(jCtx.get(key2)), None)
+    }
+  }
+
+  test("works as a Java-only ContextStorage") {
+    usingModifiedCtx(_.`with`(key1, "1")) {
+      assertEquals(Option(jCurrent.get(key1)), Some("1"))
+      assertEquals(Option(jCurrent.get(key2)), None)
+
+      usingModifiedCtx(_.`with`(key2, 2)) {
+        assertEquals(Option(jCurrent.get(key1)), Some("1"))
+        assertEquals(Option(jCurrent.get(key2)), Some(2))
+
+        usingModifiedCtx(_ => JContext.root()) {
+          assertEquals(Option(jCurrent.get(key1)), None)
+          assertEquals(Option(jCurrent.get(key2)), None)
+        }
+      }
+    }
+  }
+
+  localTest("works as a Scala-only Local") { implicit L =>
+    doLocally(_.updated(key1, "1")) {
+      for {
+        _ <- doLocally(_.updated(key2, 2)) {
+          for {
+            _ <- doScoped(Context.root) {
+              for (ctx <- sCurrent)
+                yield {
+                  assertEquals(ctx.get(key1), None)
+                  assertEquals(ctx.get(key2), None)
+                }
+            }
+            ctx <- sCurrent
+          } yield {
+            assertEquals(ctx.get(key1), Some("1"))
+            assertEquals(ctx.get(key2), Some(2))
+          }
+        }
+        ctx <- sCurrent
+      } yield {
+        assertEquals(ctx.get(key1), Some("1"))
+        assertEquals(ctx.get(key2), None)
+      }
+    }
+  }
+
+  localTest("Scala with Java nested inside it") { implicit L =>
+    doLocally(_.updated(key1, "1")) {
+      for {
+        _ <- IO {
+          usingModifiedCtx(_.`with`(key2, 2)) {
+            val sCtx = sCurrent.unsafeRunSync()
+            val jCtx = jCurrent
+            assertEquals(jCtx, sCtx.underlying)
+            assertEquals(sCtx.get(key1), Some("1"))
+            assertEquals(sCtx.get(key2), Some(2))
+            assertEquals(Option(jCtx.get(key1)), Some("1"))
+            assertEquals(Option(jCtx.get(key2)), Some(2))
+          }
+        }
+        sCtx <- sCurrent
+        jCtx <- IO(jCurrent)
+      } yield {
+        assertEquals(jCtx, sCtx.underlying)
+        assertEquals(sCtx.get(key1), Some("1"))
+        assertEquals(sCtx.get(key2), None)
+        assertEquals(Option(jCtx.get(key1)), Some("1"))
+        assertEquals(Option(jCtx.get(key2)), None)
+      }
+    }
+  }
+
+  localTest("Java with Scala nested inside it") { implicit L =>
+    IO {
+      usingModifiedCtx(_.`with`(key1, "1")) {
+        val sCtx = locally {
+          for {
+            _ <- doLocally(_.updated(key2, 2)) {
+              for {
+                sCtx <- sCurrent
+                jCtx <- IO(jCurrent)
+              } yield {
+                assertEquals(jCtx, sCtx.underlying)
+                assertEquals(sCtx.get(key1), Some("1"))
+                assertEquals(sCtx.get(key2), Some(2))
+                assertEquals(Option(jCtx.get(key1)), Some("1"))
+                assertEquals(Option(jCtx.get(key2)), Some(2))
+              }
+            }
+            ctx <- sCurrent
+          } yield ctx
+        }.unsafeRunSync()
+        val jCtx = jCurrent
+        assertEquals(jCtx, sCtx.underlying)
+        assertEquals(sCtx.get(key1), Some("1"))
+        assertEquals(sCtx.get(key2), None)
+        assertEquals(Option(jCtx.get(key1)), Some("1"))
+        assertEquals(Option(jCtx.get(key2)), None)
+      }
+    }
+  }
+
+  localTest("lots of nesting") { implicit L =>
+    doLocally(_.updated(key1, "1")) {
+      for {
+        _ <- IO {
+          usingModifiedCtx(_.`with`(key2, 2)) {
+            usingModifiedCtx(_.`with`(key1, "3")) {
+              val sCtx = locally {
+                for {
+                  _ <- doLocally(_.updated(key2, 4)) {
+                    for {
+                      sCtx <- sCurrent
+                      jCtx <- IO(jCurrent)
+                    } yield {
+                      assertEquals(jCtx, sCtx.underlying)
+                      assertEquals(sCtx.get(key1), Some("3"))
+                      assertEquals(sCtx.get(key2), Some(4))
+                      assertEquals(Option(jCtx.get(key1)), Some("3"))
+                      assertEquals(Option(jCtx.get(key2)), Some(4))
+                    }
+                  }
+                  ctx <- sCurrent
+                } yield ctx
+              }.unsafeRunSync()
+              val jCtx = jCurrent
+              assertEquals(jCtx, sCtx.underlying)
+              assertEquals(sCtx.get(key1), Some("3"))
+              assertEquals(sCtx.get(key2), Some(2))
+              assertEquals(Option(jCtx.get(key1)), Some("3"))
+              assertEquals(Option(jCtx.get(key2)), Some(2))
+            }
+            val sCtx = locally {
+              for {
+                _ <- doScoped(Context.root) {
+                  for {
+                    sCtx <- sCurrent
+                    jCtx <- IO(jCurrent)
+                  } yield {
+                    assertEquals(jCtx, sCtx.underlying)
+                    assertEquals(sCtx.get(key1), None)
+                    assertEquals(sCtx.get(key2), None)
+                    assertEquals(Option(jCtx.get(key1)), None)
+                    assertEquals(Option(jCtx.get(key2)), None)
+                  }
+                }
+                ctx <- sCurrent
+              } yield ctx
+            }.unsafeRunSync()
+            val jCtx = jCurrent
+            assertEquals(jCtx, sCtx.underlying)
+            assertEquals(sCtx.get(key1), Some("1"))
+            assertEquals(sCtx.get(key2), Some(2))
+            assertEquals(Option(jCtx.get(key1)), Some("1"))
+            assertEquals(Option(jCtx.get(key2)), Some(2))
+          }
+        }
+        sCtx <- sCurrent
+        jCtx <- IO(jCurrent)
+      } yield {
+        assertEquals(jCtx, sCtx.underlying)
+        assertEquals(sCtx.get(key1), Some("1"))
+        assertEquals(sCtx.get(key2), None)
+        assertEquals(Option(jCtx.get(key1)), Some("1"))
+        assertEquals(Option(jCtx.get(key2)), None)
+      }
+    }
+  }
+}
+
+object IOLocalContextStorageSuite {
+  private val keyProvider = Key.Provider[SyncIO, Context.Key]
+  val key1: Context.Key[String] =
+    keyProvider.uniqueKey[String]("key1").unsafeRunSync()
+  val key2: Context.Key[Int] =
+    keyProvider.uniqueKey[Int]("key2").unsafeRunSync()
+
+  // `Local`'s methods have their argument lists in the an annoying order
+  def doLocally[F[_], A](f: Context => Context)(fa: F[A])(implicit
+      L: LocalContext[F]
+  ): F[A] =
+    L.local(fa)(f)
+  def doScoped[F[_], A](e: Context)(fa: F[A])(implicit
+      L: LocalContext[F]
+  ): F[A] =
+    L.scope(fa)(e)
+}

From 39ba75452b89226b6e07f655a84b3d81ee258ff0 Mon Sep 17 00:00:00 2001
From: Marissa <dev@princess.lgbt>
Date: Wed, 4 Oct 2023 15:00:23 -0400
Subject: [PATCH 15/15] fixup! Finish implementing `IOLocalContextStorage`

fix docs
---
 .../otel4s/java/IOLocalContextStorage.scala      | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/java/context-storage/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala b/java/context-storage/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
index ed767622e..3e0edc1c6 100644
--- a/java/context-storage/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
+++ b/java/context-storage/src/main/scala/org/typelevel/otel4s/java/IOLocalContextStorage.scala
@@ -28,10 +28,10 @@ import org.typelevel.otel4s.java.context.LocalContext
 import org.typelevel.otel4s.java.instances._
 
 /** A `ContextStorage` backed by an [[cats.effect.IOLocal `IOLocal`]] of a
-  * [[`Context`]] that also provides [[cats.mtl.Local `Local`]] instances that
-  * reflect the state of the backing `IOLocal`. Usage of `Local` and
-  * `ContextStorage` methods will be consistent and stay in sync as long as
-  * effects are threaded properly.
+  * [[org.typelevel.otel4s.java.context.Context `Context`]] that also provides
+  * [[cats.mtl.Local `Local`]] instances that reflect the state of the backing
+  * `IOLocal`. Usage of `Local` and `ContextStorage` methods will be consistent
+  * and stay in sync as long as effects are threaded properly.
   */
 class IOLocalContextStorage(_ioLocal: () => IOLocal[Context])
     extends ContextStorage {
@@ -50,15 +50,17 @@ class IOLocalContextStorage(_ioLocal: () => IOLocal[Context])
     unsafeCurrent.underlying
 
   /** @return
-    *   a [[cats.mtl.Local `Local`]] of a [[`Context`]] that reflects the state
-    *   of the backing `IOLocal`
+    *   a [[cats.mtl.Local `Local`]] of a
+    *   [[org.typelevel.otel4s.java.context.Context `Context`]] that reflects
+    *   the state of the backing `IOLocal`
     */
   def local[F[_]: MonadCancelThrow: LiftIO]: LocalContext[F] = implicitly
 }
 
 object IOLocalContextStorage {
 
-  /** Returns a [[cats.mtl.Local `Local`]] of a [[`Context`]] if an
+  /** Returns a [[cats.mtl.Local `Local`]] of a
+    * [[org.typelevel.otel4s.java.context.Context `Context`]] if an
     * [[`IOLocalContextStorage`]] is configured to be used as the
     * `ContextStorage` for the Java otel library.
     *