Add velocity-backend-redis: the sliding hot-path reference backend

settings.gradle.kts

@@ -59,7 +59,7 @@ include("velocity-testkit")  // in-memory velocity-spi impl, conformance TCK sce
 
 // Phase 2 — v1 reference backends (tumbling + sliding), the service tier, and the generated client.
 include("velocity-backend-jdbi")   // Postgres/JDBI backend — v1 tumbling reference
-// include("velocity-backend-redis")  // Redis/Lettuce backend — v1 sliding / hot-path reference
+include("velocity-backend-redis")  // Redis/Lettuce backend — v1 sliding / hot-path reference
 // include("velocity-dropwizard")     // Dropwizard bundle, Jersey resources, Dagger wiring, API-key auth
 // include("velocity-client-java")    // Java client generated from OpenAPI via openapi-generator
 // include("examples:dropwizard-demo")// runnable reference service (not published)

velocity-backend-redis/build.gradle.kts

@@ -0,0 +1,46 @@
+plugins {
+    id("velocity.library-conventions")
+    id("velocity.test-conventions")
+    id("velocity.publish-conventions")
+}
+
+description =
+    "velocity-backend-redis: the v1 Redis/Lettuce sliding hot-path reference backend — an exact," +
+        " atomic, read-your-write VelocityBackend (COUNT/SUM/DISTINCT over true sliding windows via" +
+        " sorted sets + Lua) that passes the velocity-testkit conformance TCK against real Redis."
+
+// Lettuce ships as an automatic module and pulls Reactor/Netty (also automatic modules); the
+// baseline -Xlint:all makes their `requires` a warning, which -Werror (library-conventions) turns
+// fatal. Silence just the automatic-module lints on both the main and test compiles (mirrors the
+// jdbi module).
+tasks.named<JavaCompile>("compileJava") {
+    options.compilerArgs.addAll(
+        listOf("-Xlint:-requires-automatic", "-Xlint:-requires-transitive-automatic"),
+    )
+}
+tasks.named<JavaCompile>("compileTestJava") {
+    options.compilerArgs.addAll(
+        listOf("-Xlint:-requires-automatic", "-Xlint:-requires-transitive-automatic"),
+    )
+}
+
+dependencies {
+    // The frozen contract this backend implements is on the api surface.
+    api(project(":velocity-spi"))
+    api(libs.jspecify)
+
+    implementation(libs.lettuce.core)
+    implementation(libs.slf4j.api)
+
+    // Reactor's class files reference com.google.errorprone.annotations.*; without errorprone
+    // annotations on the compile classpath javac emits an annotation-not-found warning that -Werror
+    // turns fatal. compileOnly so it is not broadcast as a runtime dependency.
+    compileOnly(libs.build.errorprone.annotations)
+    testCompileOnly(libs.build.errorprone.annotations)
+
+    // The testkit drives the conformance TCK (*Scenarios) + MutableClock against this backend.
+    testImplementation(project(":velocity-testkit"))
+    testImplementation(libs.testcontainers.core)
+    testImplementation(libs.testcontainers.junit.jupiter)
+    testRuntimeOnly(libs.logback.classic)
+}