diff --git a/.idea/modules.xml b/.idea/modules.xml
index 086a6a9cb4ad..8d131a60d490 100644
--- a/.idea/modules.xml
+++ b/.idea/modules.xml
@@ -24,6 +24,7 @@
       <module fileurl="file://$PROJECT_DIR$/fleet/ktor/network/tls/fleet.ktor.network.tls.iml" filepath="$PROJECT_DIR$/fleet/ktor/network/tls/fleet.ktor.network.tls.iml" />
       <module fileurl="file://$PROJECT_DIR$/fleet/ktor/server/cio/fleet.ktor.server.cio.iml" filepath="$PROJECT_DIR$/fleet/ktor/server/cio/fleet.ktor.server.cio.iml" />
       <module fileurl="file://$PROJECT_DIR$/fleet/lsp.protocol/fleet.lsp.protocol.iml" filepath="$PROJECT_DIR$/fleet/lsp.protocol/fleet.lsp.protocol.iml" />
+      <module fileurl="file://$PROJECT_DIR$/fleet/lsp.protocol/test/fleet.lsp.protocol.test.iml" filepath="$PROJECT_DIR$/fleet/lsp.protocol/test/fleet.lsp.protocol.test.iml" />
       <module fileurl="file://$PROJECT_DIR$/fleet/modules/api/fleet.modules.api.iml" filepath="$PROJECT_DIR$/fleet/modules/api/fleet.modules.api.iml" />
       <module fileurl="file://$PROJECT_DIR$/fleet/modules/jvm/fleet.modules.jvm.iml" filepath="$PROJECT_DIR$/fleet/modules/jvm/fleet.modules.jvm.iml" />
       <module fileurl="file://$PROJECT_DIR$/fleet/multiplatform.shims/fleet.multiplatform.shims.iml" filepath="$PROJECT_DIR$/fleet/multiplatform.shims/fleet.multiplatform.shims.iml" />
diff --git a/build/bazel-generated-file-list.txt b/build/bazel-generated-file-list.txt
index 57842044c818..41b2ce271e64 100644
--- a/build/bazel-generated-file-list.txt
+++ b/build/bazel-generated-file-list.txt
@@ -240,6 +240,7 @@ fleet/ktor/client/core
 fleet/ktor/network/tls
 fleet/ktor/server/cio
 fleet/lsp.protocol
+fleet/lsp.protocol/test
 fleet/modules/api
 fleet/modules/jvm
 fleet/multiplatform.shims
diff --git a/fleet/lsp.protocol/test/BUILD.bazel b/fleet/lsp.protocol/test/BUILD.bazel
new file mode 100644
index 000000000000..4f08dcf384e3
--- /dev/null
+++ b/fleet/lsp.protocol/test/BUILD.bazel
@@ -0,0 +1,55 @@
+### auto-generated section `build fleet.lsp.protocol.test` start
+load("//build:compiler-options.bzl", "create_kotlinc_options")
+load("@rules_jvm//:jvm.bzl", "jvm_library")
+
+create_kotlinc_options(
+  name = "custom_test",
+  opt_in = [
+    "kotlinx.coroutines.ExperimentalCoroutinesApi",
+    "kotlinx.serialization.ExperimentalSerializationApi",
+    "kotlin.concurrent.atomics.ExperimentalAtomicApi",
+  ],
+  x_consistent_data_class_copy_visibility = True,
+  x_context_parameters = True,
+  x_lambdas = "class"
+)
+
+jvm_library(
+  name = "test",
+  visibility = ["//visibility:public"],
+  srcs = glob([], allow_empty = True, exclude = ["**/module-info.java"]),
+  runtime_deps = [
+    "@lib//:kotlin-stdlib",
+    "@lib//:kotlinx-coroutines-core",
+    "@lib//:kotlinx-io-core",
+  ]
+)
+
+jvm_library(
+  name = "test_test_lib",
+  module_name = "fleet.lsp.protocol.test",
+  visibility = ["//visibility:public"],
+  srcs = glob(["src/**/*.kt", "src/**/*.java", "src/**/*.form"], allow_empty = True, exclude = ["**/module-info.java"]),
+  kotlinc_opts = ":custom_test",
+  deps = [
+    "@lib//:kotlin-stdlib",
+    "@lib//:kotlinx-coroutines-core",
+    "@lib//:kotlinx-io-core",
+    "//fleet/ktor/client/cio",
+    "//fleet/ktor/client/core",
+    "//fleet/ktor/network/tls",
+    "//fleet/lsp.protocol",
+    "//fleet/test-runtime",
+  ],
+  runtime_deps = [":test"]
+)
+### auto-generated section `build fleet.lsp.protocol.test` end
+
+### auto-generated section `test fleet.lsp.protocol.test` start
+load("@community//build:tests-options.bzl", "jps_test")
+
+jps_test(
+  name = "test_test",
+  runtime_deps = [":test_test_lib"]
+)
+### auto-generated section `test fleet.lsp.protocol.test` end
\ No newline at end of file
diff --git a/fleet/lsp.protocol/test/fleet.lsp.protocol.test.iml b/fleet/lsp.protocol/test/fleet.lsp.protocol.test.iml
new file mode 100644
index 000000000000..c54e2f4e2645
--- /dev/null
+++ b/fleet/lsp.protocol/test/fleet.lsp.protocol.test.iml
@@ -0,0 +1,35 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="FacetManager">
+    <facet type="kotlin-language" name="Kotlin">
+      <configuration version="5" platform="JVM 21" allPlatforms="JVM [21]" useProjectSettings="false">
+        <compilerSettings>
+          <option name="additionalArguments" value="-opt-in=kotlinx.coroutines.ExperimentalCoroutinesApi -Xlambdas=class -Xconsistent-data-class-copy-visibility -opt-in=kotlinx.serialization.ExperimentalSerializationApi -Xcontext-parameters -Xjvm-default=all -XXLanguage:+AllowEagerSupertypeAccessibilityChecks -opt-in=kotlin.concurrent.atomics.ExperimentalAtomicApi -progressive" />
+        </compilerSettings>
+        <compilerArguments>
+          <stringArguments>
+            <stringArg name="jvmTarget" arg="21" />
+            <stringArg name="apiVersion" arg="2.3" />
+            <stringArg name="languageVersion" arg="2.3" />
+          </stringArguments>
+        </compilerArguments>
+      </configuration>
+    </facet>
+  </component>
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="true" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+    <orderEntry type="library" name="kotlin-stdlib" level="project" />
+    <orderEntry type="library" name="kotlinx-coroutines-core" level="project" />
+    <orderEntry type="library" name="kotlinx-io-core" level="project" />
+    <orderEntry type="module" module-name="fleet.ktor.client.cio" scope="TEST" />
+    <orderEntry type="module" module-name="fleet.ktor.client.core" scope="TEST" />
+    <orderEntry type="module" module-name="fleet.ktor.network.tls" scope="TEST" />
+    <orderEntry type="module" module-name="fleet.lsp.protocol" scope="TEST" />
+    <orderEntry type="module" module-name="fleet.test.runtime" scope="TEST" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/fleet/lsp.protocol/test/gradlebuild/build.gradle.kts b/fleet/lsp.protocol/test/gradlebuild/build.gradle.kts
new file mode 100644
index 000000000000..aca461499cf1
--- /dev/null
+++ b/fleet/lsp.protocol/test/gradlebuild/build.gradle.kts
@@ -0,0 +1,72 @@
+// IMPORT__MARKER_START
+import fleet.buildtool.conventions.configureAtMostOneJvmTargetOrThrow
+import fleet.buildtool.conventions.withJavaSourceSet
+// IMPORT__MARKER_END
+plugins {
+  alias(libs.plugins.kotlin.multiplatform)
+  id("fleet.project-module-conventions")
+  id("fleet.toolchain-conventions")
+  id("fleet.module-publishing-conventions")
+  id("fleet.sdk-repositories-publishing-conventions")
+  id("fleet.open-source-module-conventions")
+  alias(libs.plugins.dokka)
+  // GRADLE_PLUGINS__MARKER_START
+  id("fleet-module")
+  // GRADLE_PLUGINS__MARKER_END
+}
+
+fleetModule {
+  module {
+    name = "fleet.lsp.protocol.test"
+    importedFromJps {}
+    test {}
+  }
+}
+
+@OptIn(org.jetbrains.kotlin.gradle.ExperimentalWasmDsl::class)
+kotlin {
+  // KOTLIN__MARKER_START
+  compilerOptions.freeCompilerArgs = listOf(
+    "-opt-in=kotlinx.coroutines.ExperimentalCoroutinesApi",
+    "-Xlambdas=class",
+    "-Xconsistent-data-class-copy-visibility",
+    "-opt-in=kotlinx.serialization.ExperimentalSerializationApi",
+    "-Xcontext-parameters",
+    "-Xjvm-default=all",
+    "-XXLanguage:+AllowEagerSupertypeAccessibilityChecks",
+    "-opt-in=kotlin.concurrent.atomics.ExperimentalAtomicApi",
+    "-progressive",
+  )
+  jvm {}
+  sourceSets.jvmTest.configure { kotlin.srcDir(layout.projectDirectory.dir("../src")) }
+  configureAtMostOneJvmTargetOrThrow { compilations.named("test") { withJavaSourceSet { javaSourceSet -> javaSourceSet.java.srcDir(layout.projectDirectory.dir("../src")) } } }
+  sourceSets.commonMain.configure { kotlin.srcDir(layout.projectDirectory.dir("../srcCommonMain")) }
+  sourceSets.commonMain.configure { resources.srcDir(layout.projectDirectory.dir("../resourcesCommonMain")) }
+  sourceSets.commonTest.configure { kotlin.srcDir(layout.projectDirectory.dir("../srcCommonTest")) }
+  sourceSets.commonTest.configure { resources.srcDir(layout.projectDirectory.dir("../resourcesCommonTest")) }
+  sourceSets.jvmMain.configure { kotlin.srcDir(layout.projectDirectory.dir("../srcJvmMain")) }
+  configureAtMostOneJvmTargetOrThrow { compilations.named("main") { withJavaSourceSet { javaSourceSet -> javaSourceSet.java.srcDir(layout.projectDirectory.dir("../srcJvmMain")) } } }
+  sourceSets.jvmMain.configure { resources.srcDir(layout.projectDirectory.dir("../resourcesJvmMain")) }
+  sourceSets.jvmTest.configure { kotlin.srcDir(layout.projectDirectory.dir("../srcJvmTest")) }
+  configureAtMostOneJvmTargetOrThrow { compilations.named("test") { withJavaSourceSet { javaSourceSet -> javaSourceSet.java.srcDir(layout.projectDirectory.dir("../srcJvmTest")) } } }
+  sourceSets.jvmTest.configure { resources.srcDir(layout.projectDirectory.dir("../resourcesJvmTest")) }
+  sourceSets.commonMain.dependencies {
+    implementation(jps.org.jetbrains.kotlin.kotlin.stdlib1993400674.get().let { "${it.group}:${it.name}:${it.version}" }) {
+      exclude(group = "org.jetbrains", module = "annotations")
+    }
+    implementation(jps.org.jetbrains.intellij.deps.kotlinx.kotlinx.coroutines.core.jvm930800474.get().let { "${it.group}:kotlinx-coroutines-core:${it.version}" }) {
+      isTransitive = false
+    }
+    implementation(jps.org.jetbrains.kotlinx.kotlinx.io.core.jvm479158162.get().let { "${it.group}:kotlinx-io-core:${it.version}" }) {
+      exclude(group = "org.jetbrains.kotlin", module = "kotlin-stdlib")
+    }
+  }
+  sourceSets.commonTest.dependencies {
+    implementation(project(":fleet.ktor.client.cio"))
+    implementation(project(":fleet.ktor.client.core"))
+    implementation(project(":fleet.ktor.network.tls"))
+    implementation(project(":fleet.lsp.protocol"))
+    implementation(project(":fleet.test.runtime"))
+  }
+  // KOTLIN__MARKER_END
+}
\ No newline at end of file
diff --git a/fleet/lsp.protocol/test/src/com/jetbrains/lsp/test/ByteReaderTest.kt b/fleet/lsp.protocol/test/src/com/jetbrains/lsp/test/ByteReaderTest.kt
new file mode 100644
index 000000000000..187387c461c7
--- /dev/null
+++ b/fleet/lsp.protocol/test/src/com/jetbrains/lsp/test/ByteReaderTest.kt
@@ -0,0 +1,129 @@
+package com.jetbrains.lsp.test
+
+import com.jetbrains.lsp.implementation.ByteReader
+import com.jetbrains.lsp.implementation.readUTF8Line
+import io.ktor.utils.io.*
+import kotlinx.coroutines.async
+import kotlinx.coroutines.flow.flow
+import kotlinx.coroutines.flow.withIndex
+import kotlinx.coroutines.runBlocking
+import kotlinx.io.Source
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+private const val LF = 0x0A.toByte()
+private const val CR = 0x0D.toByte()
+
+class ByteReaderTest {
+
+  @Test
+  fun `readUTF8Line reads an LF-terminated line`() {
+    runBlocking {
+      val message = "Hello, world!"
+      val channel = ByteChannel()
+      val reader = ByteChannelReader(channel)
+
+      val line = async { reader.readUTF8Line() }
+      channel.writeLine(message, LF)
+      channel.flushAndClose()
+
+      assertEquals(message, line.await())
+    }
+  }
+
+  @Test
+  fun `readUTF8Line reads an LF-terminated line sent byte by byte`() {
+    runBlocking {
+      val message = "Hello, world!"
+      val channel = ByteChannel()
+      val reader = ByteChannelReader(channel)
+
+      val line = async { reader.readUTF8Line() }
+      message.toByteArray(Charsets.UTF_8).forEach { byte ->
+        channel.writeByte(byte)
+        channel.flush()
+      }
+      channel.writeByte(LF)
+      channel.flushAndClose()
+
+      assertEquals(message, line.await())
+    }
+  }
+
+  @Test
+  fun `readUTF8Line reads a CRLF-terminated line sent byte by byte`() {
+    runBlocking {
+      val message = "Hello, world!"
+      val channel = ByteChannel()
+      val reader = ByteChannelReader(channel)
+
+      val line = async { reader.readUTF8Line() }
+      message.toByteArray(Charsets.UTF_8).forEach { byte ->
+        channel.writeByte(byte)
+        channel.flush()
+      }
+      channel.writeBytes(CR, LF)
+      channel.flushAndClose()
+
+      assertEquals(message, line.await())
+    }
+  }
+
+  @Test
+  fun `readUTF8Line reads several LF-terminated lines`() {
+    runBlocking {
+      val messages = listOf(
+        "Hello", "world", "how", "are", "you", "doing"
+      )
+      val channel = ByteChannel()
+      val reader = ByteChannelReader(channel)
+
+      val lines = flow {
+        while (!reader.isClosedForRead) {
+          emit(reader.readUTF8Line())
+        }
+      }
+
+      for (message in messages) {
+        channel.writeLine(message, LF)
+        channel.flush()
+      }
+      channel.close()
+
+      lines.withIndex().collect { (i, line) ->
+        assertEquals(messages[i], line)
+      }
+    }
+  }
+
+  private suspend fun ByteWriteChannel.writeBytes(vararg bytes: Byte) {
+    for (byte in bytes) {
+      writeByte(byte)
+    }
+  }
+
+  private suspend fun ByteWriteChannel.writeLine(s: String, vararg terminators: Byte = byteArrayOf(LF)) {
+    writeStringUtf8(s)
+    for (terminator in terminators) {
+      writeByte(terminator)
+    }
+  }
+}
+
+@OptIn(InternalAPI::class)
+internal class ByteChannelReader(val underlying: ByteChannel) : ByteReader {
+  override val closedCause: Throwable?
+    get() = underlying.closedCause
+  override val isClosedForRead: Boolean
+    get() = underlying.isClosedForRead
+  override val readBuffer: Source
+    get() = underlying.readBuffer
+
+  override suspend fun awaitContent(min: Int): Boolean {
+    return underlying.awaitContent()
+  }
+
+  override fun cancel(cause: Throwable?) {
+    underlying.cancel(cause)
+  }
+}
\ No newline at end of file