diff --git a/.travis.yml b/.travis.yml
index f330307..28ad4ae 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,7 @@ jdk:
 scala:
   - 2.11.8
 
-script: sbt ++$TRAVIS_SCALA_VERSION clean compile
+script: sbt ++$TRAVIS_SCALA_VERSION clean coverageTest
 
 cache:
   directories:
@@ -14,6 +14,8 @@ cache:
   - $HOME/.sbt/boot/
   - $HOME/.zinc
 
+after_success: sbt ++$TRAVIS_SCALA_VERSION travis-report
+
 before_cache:
   # Tricks to avoid unnecessary cache updates
   - find $HOME/.ivy2 -name "ivydata-*.properties" -delete
diff --git a/README.md b/README.md
index 25997f4..6cf5789 100644
--- a/README.md
+++ b/README.md
@@ -1,5 +1,17 @@
 # spark-commands
 
-[![Maven Central](https://img.shields.io/maven-central/v/org.hammerlab/spark-commands_2.11.svg?maxAge=600)](http://search.maven.org/#search%7Cga%7C1%7Cspark-commands)
+[![Build Status](https://travis-ci.org/hammerlab/spark-commands.svg?branch=master)](https://travis-ci.org/hammerlab/spark-commands)
+[![Coverage Status](https://coveralls.io/repos/github/hammerlab/spark-commands/badge.svg)](https://coveralls.io/github/hammerlab/spark-commands)
+
+Interfaces for creating CLI-runnable and testable commands/apps, with [Spark](http://spark.apache.org/)-based and non-Spark flavors.
+
+## args4j
+[![Maven Central](https://img.shields.io/maven-central/v/org.hammerlab.cli/args4j_2.11.svg?maxAge=600)](http://search.maven.org/#search%7Cga%7C1%7Chammerlab%20args4j)
+
+
+## case-app
+[![Maven Central](https://img.shields.io/maven-central/v/org.hammerlab.cli/case-app_2.11.svg?maxAge=600)](http://search.maven.org/#search%7Cga%7C1%7Chammerlab%20case-app)
+
+
+
 
-Interfaces for creating CLI-runnable and testable Spark commands/apps.
diff --git a/src/main/scala/org/hammerlab/commands/Args.scala b/args4j/src/main/scala/org/hammerlab/cli/args4j/Args.scala
similarity index 65%
rename from src/main/scala/org/hammerlab/commands/Args.scala
rename to args4j/src/main/scala/org/hammerlab/cli/args4j/Args.scala
index 3ed8ec8..722e5ea 100644
--- a/src/main/scala/org/hammerlab/commands/Args.scala
+++ b/args4j/src/main/scala/org/hammerlab/cli/args4j/Args.scala
@@ -1,8 +1,9 @@
-package org.hammerlab.commands
+package org.hammerlab.cli.args4j
 
 import org.apache.spark.SparkContext
 import org.bdgenomics.utils.cli.Args4jBase
 
-trait Args extends Args4jBase {
+trait Args
+  extends Args4jBase {
   def validate(sc: SparkContext): Unit = {}
 }
diff --git a/src/main/scala/org/hammerlab/commands/Command.scala b/args4j/src/main/scala/org/hammerlab/cli/args4j/Command.scala
similarity index 80%
rename from src/main/scala/org/hammerlab/commands/Command.scala
rename to args4j/src/main/scala/org/hammerlab/cli/args4j/Command.scala
index c588b41..0e8fddf 100644
--- a/src/main/scala/org/hammerlab/commands/Command.scala
+++ b/args4j/src/main/scala/org/hammerlab/cli/args4j/Command.scala
@@ -1,4 +1,4 @@
-package org.hammerlab.commands
+package org.hammerlab.cli.args4j
 
 import grizzled.slf4j.Logging
 import org.bdgenomics.utils.cli.Args4j
@@ -21,7 +21,12 @@ abstract class Command[T <: Args: Manifest]
    *
    * @param args the command line arguments.
    */
-  def run(args: Array[String]): Unit = run(Args4j[T](args))
+  def run(args: Array[String]): Unit =
+    Args4j[T](args) match {
+      case Left(args) ⇒ run(args)
+      case _ ⇒
+    }
+
   def run(args: String*): Unit = run(args.toArray)
 
   def run(args: T): Unit
diff --git a/args4j/src/main/scala/org/hammerlab/cli/args4j/SparkCommand.scala b/args4j/src/main/scala/org/hammerlab/cli/args4j/SparkCommand.scala
new file mode 100644
index 0000000..e2684ca
--- /dev/null
+++ b/args4j/src/main/scala/org/hammerlab/cli/args4j/SparkCommand.scala
@@ -0,0 +1,39 @@
+package org.hammerlab.cli.args4j
+
+import org.apache.spark.SparkContext
+import org.hammerlab.spark.{ SparkConfBase, confs }
+
+abstract class SparkCommand[T <: Args: Manifest]
+  extends Command[T]
+    with SparkConfBase
+    with confs.Kryo {
+
+  override def run(args: T): Unit = {
+    val sc = createSparkContext()
+    try {
+      args.validate(sc)
+      run(args, sc)
+    } finally {
+      sc.stop()
+    }
+  }
+
+  def run(args: T, sc: SparkContext): Unit
+
+  /**
+   * Return a spark context.
+   *
+   * Typically, most properties are set through config file / cmd-line.
+   * @return
+   */
+  private def createSparkContext(): SparkContext = {
+    val conf = makeSparkConf
+
+    conf.getOption("spark.app.name") match {
+      case Some(cmdLineName) => conf.setAppName(s"$cmdLineName: $name")
+      case _ => conf.setAppName(name)
+    }
+
+    new SparkContext(conf)
+  }
+}
diff --git a/args4j/src/test/scala/org/hammerlab/cli/args4j/SparkCommandTest.scala b/args4j/src/test/scala/org/hammerlab/cli/args4j/SparkCommandTest.scala
new file mode 100644
index 0000000..943e40e
--- /dev/null
+++ b/args4j/src/test/scala/org/hammerlab/cli/args4j/SparkCommandTest.scala
@@ -0,0 +1,67 @@
+package org.hammerlab.cli.args4j
+
+import com.esotericsoftware.kryo.Kryo
+import org.apache.spark.SparkContext
+import org.apache.spark.serializer.KryoRegistrator
+import org.hammerlab.paths.Path
+import org.hammerlab.test.Suite
+import org.kohsuke.args4j.Argument
+
+class SparkCommandTest
+  extends Suite {
+  test("command") {
+    val outFile = tmpPath()
+
+    TestCommand.main(
+      Array(
+        outFile.toString
+      )
+    )
+
+    outFile
+      .lines
+      .toList should be(
+      List(
+        "8mb",
+        "org.hammerlab.cli.args4j.TestRegistrar"
+      )
+    )
+  }
+}
+
+class TestArgs
+  extends Args {
+  @Argument(required = true)
+  var outFile: String = _
+}
+
+class TestRegistrar
+  extends KryoRegistrator {
+  override def registerClasses(kryo: Kryo): Unit = {}
+}
+
+import org.hammerlab.spark.test.suite.TestConfs
+
+object TestCommand
+  extends SparkCommand[TestArgs]
+    with TestConfs {
+
+  override def name: String = "test"
+  override def description: String = "test command"
+
+  sparkConf(
+    "spark.kryoserializer.buffer" → "8mb"
+  )
+
+  override def registrar = classOf[TestRegistrar]
+
+  override def run(args: TestArgs, sc: SparkContext): Unit = {
+    val conf = sc.getConf
+    Path(args.outFile).writeLines(
+      List(
+        conf.get("spark.kryoserializer.buffer"),
+        conf.get("spark.kryo.registrator")
+      )
+    )
+  }
+}
diff --git a/build.sbt b/build.sbt
index 95da9be..aad3982 100644
--- a/build.sbt
+++ b/build.sbt
@@ -1,9 +1,33 @@
-name := "spark-commands"
-version := "1.0.4"
 
-providedDeps += spark.value
+val defaults = Seq(
+  organization := "org.hammerlab.cli",
+  deps ++= Seq(
+    slf4j,
+    spark_util % "1.3.0"
+  )
+) ++ addSparkDeps
 
-deps ++= Seq(
-  libs.value('bdg_utils_cli),
-  libs.value('slf4j)
+lazy val args4j = project.settings(
+  defaults,
+  version := "1.1.0-SNAPSHOT",
+  deps += bdg_utils_cli % "0.3.0",
+  testDeps += Parent.autoImport.args4j
 )
+
+lazy val case_app = project.settings(
+  defaults,
+  name := "case-app",
+  version := "1.0.0-SNAPSHOT",
+  deps ++= Seq(
+    Parent.autoImport.case_app,
+    io % "1.2.0",
+    paths % "1.2.0"
+  )
+)
+
+lazy val cli_root =
+  rootProject(
+    "cli-root",
+    args4j,
+    case_app
+  )
diff --git a/case_app/src/main/scala/org/hammerlab/cli/app/App.scala b/case_app/src/main/scala/org/hammerlab/cli/app/App.scala
new file mode 100644
index 0000000..d723355
--- /dev/null
+++ b/case_app/src/main/scala/org/hammerlab/cli/app/App.scala
@@ -0,0 +1,34 @@
+package org.hammerlab.cli.app
+
+import caseapp.core.Messages
+import caseapp.{ CaseApp, Parser, RemainingArgs }
+import grizzled.slf4j.Logging
+
+abstract class App[Args : Parser : Messages]
+  extends CaseApp[Args]
+    with Logging {
+
+  final override def run(options: Args, remainingArgs: RemainingArgs): Unit =
+    remainingArgs match {
+      case RemainingArgs(args, Nil) ⇒
+        run(
+          options,
+          args
+        )
+      case RemainingArgs(args, unparsed) ⇒
+        throw new IllegalArgumentException(
+          s"Unparsed arguments: ${unparsed.mkString(" ")}"
+        )
+    }
+
+  def done(): Unit = {}
+
+  final def run(options: Args, remainingArgs: Seq[String]): Unit =
+    try {
+      _run(options, remainingArgs)
+    } finally {
+      done()
+    }
+
+  protected def _run(options: Args, remainingArgs: Seq[String]): Unit
+}
diff --git a/case_app/src/main/scala/org/hammerlab/cli/app/IndexingApp.scala b/case_app/src/main/scala/org/hammerlab/cli/app/IndexingApp.scala
new file mode 100644
index 0000000..e6256cf
--- /dev/null
+++ b/case_app/src/main/scala/org/hammerlab/cli/app/IndexingApp.scala
@@ -0,0 +1,36 @@
+package org.hammerlab.cli.app
+
+import caseapp.Parser
+import caseapp.core.Messages
+import org.hammerlab.io.Printer
+import org.hammerlab.paths.Path
+
+trait OutPathArgs {
+  def out: Option[Path]
+}
+
+/**
+ * Interface for apps that take a [[Path]] and "index" it in some way, generating an output file that is by default
+ * named by appending an extension to the input path.
+ *
+ * @param defaultSuffix if [[OutPathArgs.out]] is empty, construct an output path by appending this string to the argument
+ *                      value [[PathApp.path]].
+ */
+abstract class IndexingApp[Args <: OutPathArgs : Parser : Messages](defaultSuffix: String)
+  extends PathApp[Args] {
+  implicit var printer: Printer = _
+
+  override def init(options: Args): Unit = {
+    printer =
+      Printer(
+        options
+          .out
+          .getOrElse(
+            path + defaultSuffix
+          )
+      )
+  }
+
+  override def close(): Unit =
+    printer.close()
+}
diff --git a/case_app/src/main/scala/org/hammerlab/cli/app/PathApp.scala b/case_app/src/main/scala/org/hammerlab/cli/app/PathApp.scala
new file mode 100644
index 0000000..ac5816d
--- /dev/null
+++ b/case_app/src/main/scala/org/hammerlab/cli/app/PathApp.scala
@@ -0,0 +1,33 @@
+package org.hammerlab.cli.app
+
+import java.io.Closeable
+
+import caseapp.Parser
+import caseapp.core.Messages
+import org.hammerlab.paths.Path
+
+abstract class PathApp[Args : Parser : Messages]
+  extends App[Args]
+    with Closeable {
+
+  @transient implicit var path: Path = _
+
+  def init(options: Args): Unit = {}
+  def close(): Unit = {}
+
+  final protected override def _run(options: Args, args: Seq[String]): Unit = {
+    if (args.size != 1) {
+      throw new IllegalArgumentException(
+        s"Exactly one argument (a BAM file path) is required"
+      )
+    }
+
+    path = Path(args.head)
+
+    init(options)
+    run(options)
+    close()
+  }
+
+  protected def run(options: Args): Unit
+}
diff --git a/case_app/src/main/scala/org/hammerlab/cli/app/SparkPathApp.scala b/case_app/src/main/scala/org/hammerlab/cli/app/SparkPathApp.scala
new file mode 100644
index 0000000..e20cbe0
--- /dev/null
+++ b/case_app/src/main/scala/org/hammerlab/cli/app/SparkPathApp.scala
@@ -0,0 +1,81 @@
+package org.hammerlab.cli.app
+
+import caseapp.Parser
+import caseapp.core.Messages
+import grizzled.slf4j.Logging
+import org.apache.spark.SparkContext
+import org.apache.spark.serializer.KryoRegistrator
+import org.hammerlab.cli.args.OutputArgs
+import org.hammerlab.hadoop.Configuration
+import org.hammerlab.io.{ Printer, SampleSize }
+import org.hammerlab.paths.Path
+import org.hammerlab.spark.{ SparkConfBase, confs }
+
+trait SparkPathAppArgs {
+  def output: OutputArgs
+}
+
+trait HasSparkConf
+  extends SparkConfBase
+    with confs.Kryo
+    with confs.DynamicAllocation
+    with confs.EventLog
+    with confs.Speculation
+
+trait SparkApp[Args]
+  extends HasSparkConf {
+
+  self: App[Args] with Logging ⇒
+
+  @transient private var _sc: SparkContext = _
+
+  implicit def sc: SparkContext = {
+    if (_sc == null) {
+      info("Creating SparkContext")
+      val conf = makeSparkConf
+      if (
+        conf.get("spark.eventLog.enabled", "true") == "true" &&
+          conf.get("spark.eventLog.dir", "") == "" &&
+          !Path("/tmp/spark-events").exists) {
+        conf.set("spark.eventLog.enabled", "false")
+        warn("Disabling event-logging because default destination /tmp/spark-events doesn't exist")
+      }
+      _sc = new SparkContext(conf)
+    }
+    _sc
+  }
+
+  implicit def conf: Configuration = sc.hadoopConfiguration
+
+  override def done(): Unit = {
+    if (_sc != null && !_sc.isStopped) {
+      info("Stopping SparkContext")
+      _sc.stop()
+    }
+    _sc = null
+  }
+}
+
+/**
+ * [[SparkApp]] that takes an input path and prints some information to stdout or a path, with optional truncation of
+ * such output.
+ */
+abstract class SparkPathApp[Args <: SparkPathAppArgs : Parser : Messages](override val registrar: Class[_ <: KryoRegistrator] = null)
+  extends PathApp[Args]
+    with SparkApp[Args] {
+
+  @transient implicit var printer: Printer = _
+  @transient implicit var printLimit: SampleSize = _
+
+  override def init(options: Args): Unit = {
+    val OutputArgs(printLim, path, overwrite) = options.output
+
+    if (path.exists(_.exists) && !overwrite)
+      throw new IllegalArgumentException(
+        s"Output path $path exists and overwrite (-f) not set"
+      )
+
+    printer = Printer(path)
+    printLimit = printLim
+  }
+}
diff --git a/case_app/src/main/scala/org/hammerlab/cli/args/OutputArgs.scala b/case_app/src/main/scala/org/hammerlab/cli/args/OutputArgs.scala
new file mode 100644
index 0000000..0034d0d
--- /dev/null
+++ b/case_app/src/main/scala/org/hammerlab/cli/args/OutputArgs.scala
@@ -0,0 +1,21 @@
+package org.hammerlab.cli.args
+
+import caseapp.{ ValueDescription, ExtraName ⇒ O, HelpMessage ⇒ M }
+import org.hammerlab.io.SampleSize
+import org.hammerlab.paths.Path
+
+case class OutputArgs(
+  @O("l")
+  @ValueDescription("num=1000000")
+  @M("When collecting samples of records/results for displaying to the user, limit to this many to avoid overloading the driver")
+  printLimit: SampleSize = SampleSize(1000000),
+
+  @O("o")
+  @ValueDescription("path")
+  @M("Print output to this file, otherwise to stdout")
+  outputPath: Option[Path] = None,
+
+  @O("f")
+  @M("Whether to overwrite the output file, if it already exists")
+  overwrite: Boolean = false
+)
diff --git a/case_app/src/test/resources/numbers b/case_app/src/test/resources/numbers
new file mode 100644
index 0000000..f00c965
--- /dev/null
+++ b/case_app/src/test/resources/numbers
@@ -0,0 +1,10 @@
+1
+2
+3
+4
+5
+6
+7
+8
+9
+10
diff --git a/case_app/src/test/scala/org/hammerlab/cli/app/IndexingAppTest.scala b/case_app/src/test/scala/org/hammerlab/cli/app/IndexingAppTest.scala
new file mode 100644
index 0000000..a4e9a61
--- /dev/null
+++ b/case_app/src/test/scala/org/hammerlab/cli/app/IndexingAppTest.scala
@@ -0,0 +1,36 @@
+package org.hammerlab.cli.app
+
+import caseapp.{ AppName, ExtraName ⇒ O }
+import org.hammerlab.paths.Path
+import org.hammerlab.test.Suite
+
+class IndexingAppTest
+  extends Suite {
+  test("SumNumbers") {
+    val in = fileCopy(path("numbers"), tmpPath())
+    SumNumbers.main(
+      Array(
+        in.toString()
+      )
+    )
+    (in + ".sum").read should be("55\n")
+  }
+}
+
+@AppName("Add up numbers from an input file, write result to a sibling file with extension '.sum'")
+case class Args(@O("o") out: Option[Path] = None)
+  extends OutPathArgs
+
+object SumNumbers
+  extends IndexingApp[Args](".sum") {
+  override protected def run(options: Args): Unit = {
+    import org.hammerlab.io.Printer._
+    import cats.implicits.catsStdShowForInt
+    echo(
+      path
+        .lines
+        .map(_.toInt)
+        .sum
+    )
+  }
+}
diff --git a/case_app/src/test/scala/org/hammerlab/cli/app/SparkPathAppTest.scala b/case_app/src/test/scala/org/hammerlab/cli/app/SparkPathAppTest.scala
new file mode 100644
index 0000000..d7f76c1
--- /dev/null
+++ b/case_app/src/test/scala/org/hammerlab/cli/app/SparkPathAppTest.scala
@@ -0,0 +1,37 @@
+package org.hammerlab.cli.app
+
+import caseapp.Recurse
+import org.hammerlab.cli.args.OutputArgs
+import org.hammerlab.spark.test.suite.MainSuite
+import org.hammerlab.test.Suite
+
+class SparkPathAppTest
+  extends MainSuite {
+  test("SumNumbersSpark") {
+    val out = tmpPath()
+    SumNumbersSpark.main(
+      Array(
+        path("numbers").toString,
+        "-o", out.toString
+      )
+    )
+    out.read should be("55\n")
+  }
+}
+
+case class SparkArgs(@Recurse output: OutputArgs)
+  extends SparkPathAppArgs
+
+object SumNumbersSpark
+  extends SparkPathApp[SparkArgs] {
+  override protected def run(options: SparkArgs): Unit = {
+    import org.hammerlab.io.Printer._
+    import cats.implicits.catsStdShowForInt
+    echo(
+      sc
+        .textFile(path.toString)
+        .map(_.toInt)
+        .reduce(_ + _)
+    )
+  }
+}
diff --git a/project/plugins.sbt b/project/plugins.sbt
index 1dd7897..c67154a 100644
--- a/project/plugins.sbt
+++ b/project/plugins.sbt
@@ -1 +1 @@
-addSbtPlugin("org.hammerlab" % "sbt-parent" % "2.0.1")
+addSbtPlugin("org.hammerlab" % "sbt-parent" % "3.2.0")
diff --git a/src/main/scala/org/hammerlab/commands/SparkCommand.scala b/src/main/scala/org/hammerlab/commands/SparkCommand.scala
deleted file mode 100644
index 78e184f..0000000
--- a/src/main/scala/org/hammerlab/commands/SparkCommand.scala
+++ /dev/null
@@ -1,77 +0,0 @@
-package org.hammerlab.commands
-
-import org.apache.spark.{SparkConf, SparkContext}
-
-import scala.collection.mutable
-
-abstract class SparkCommand[T <: Args: Manifest]
-  extends Command[T] {
-
-  override def run(args: T): Unit = {
-    val sc = createSparkContext()
-    try {
-      args.validate(sc)
-      run(args, sc)
-    } finally {
-      sc.stop()
-    }
-  }
-
-  def run(args: T, sc: SparkContext): Unit
-
-  private val defaultConfs = mutable.HashMap[String, String]()
-  def setDefaultConf(key: String, value: String): Unit = {
-    defaultConfs.update(key, value)
-  }
-
-  def defaultRegistrar: String = ""
-
-  /**
-   * Return a spark context.
-   *
-   * Typically, most properties are set through config file / cmd-line.
-   * @return
-   */
-  private def createSparkContext(): SparkContext = {
-    val config: SparkConf = new SparkConf()
-
-    config.getOption("spark.app.name") match {
-      case Some(cmdLineName) => config.setAppName(s"$cmdLineName: $name")
-      case _ => config.setAppName(name)
-    }
-
-    if (config.getOption("spark.master").isEmpty) {
-      val numProcessors = Runtime.getRuntime.availableProcessors()
-      config.setMaster(s"local[$numProcessors]")
-      info(s"Running in local mode with $numProcessors 'executors'")
-    }
-
-    if (config.getOption("spark.serializer").isEmpty) {
-      config.set("spark.serializer", "org.apache.spark.serializer.KryoSerializer")
-    }
-
-    if (config.getOption("spark.kryo.registrator").isEmpty && defaultRegistrar.nonEmpty) {
-      config.set("spark.kryo.registrator", defaultRegistrar)
-    }
-
-    if (config.getOption("spark.kryoserializer.buffer").isEmpty) {
-      config.set("spark.kryoserializer.buffer", "4mb")
-    }
-
-    if (config.getOption("spark.kryo.referenceTracking").isEmpty) {
-      config.set("spark.kryo.referenceTracking", "true")
-    }
-
-    if (config.getOption("spark.kryo.registrationRequired").isEmpty) {
-      config.set("spark.kryo.registrationRequired", "true")
-    }
-
-    for {
-      (k, v) <- defaultConfs
-    } {
-      config.set(k, v)
-    }
-
-    new SparkContext(config)
-  }
-}