diff --git a/pkg/universe.dagger.io/examples/changelog.com/orig/main.cue b/pkg/universe.dagger.io/examples/changelog.com/_prototypes/0.1/main.cue
similarity index 99%
rename from pkg/universe.dagger.io/examples/changelog.com/orig/main.cue
rename to pkg/universe.dagger.io/examples/changelog.com/_prototypes/0.1/main.cue
index ee334997..64a4649f 100644
--- a/pkg/universe.dagger.io/examples/changelog.com/orig/main.cue
+++ b/pkg/universe.dagger.io/examples/changelog.com/_prototypes/0.1/main.cue
@@ -40,7 +40,7 @@ test_db_container_name: "changelog_test_postgres"
 //    - caching is buildkit layers
 //
 // 3. Open Telemetry integration out-of-the-box
-//    - visualize all steps in Jaeger UI
+//    - visualise all steps in Jaeger UI
 
 // PIPELINE OVERVIEW ###########################################################
 //
diff --git a/pkg/universe.dagger.io/examples/changelog.com/lowlevel/README.md b/pkg/universe.dagger.io/examples/changelog.com/_prototypes/joel/README.md
similarity index 100%
rename from pkg/universe.dagger.io/examples/changelog.com/lowlevel/README.md
rename to pkg/universe.dagger.io/examples/changelog.com/_prototypes/joel/README.md
diff --git a/pkg/universe.dagger.io/examples/changelog.com/lowlevel/main.cue b/pkg/universe.dagger.io/examples/changelog.com/_prototypes/joel/main.cue
similarity index 100%
rename from pkg/universe.dagger.io/examples/changelog.com/lowlevel/main.cue
rename to pkg/universe.dagger.io/examples/changelog.com/_prototypes/joel/main.cue
diff --git a/pkg/universe.dagger.io/examples/changelog.com/commented.cue b/pkg/universe.dagger.io/examples/changelog.com/commented.cue
new file mode 100644
index 00000000..22227a07
--- /dev/null
+++ b/pkg/universe.dagger.io/examples/changelog.com/commented.cue
@@ -0,0 +1,101 @@
+package changelog
+
+actions: {
+	// Reuse in all mix commands
+
+	// prod: assets: docker.#Build & {
+	//  steps: [
+	//   // 1. Start from dev assets :)
+	//   dev.assets,
+	//   // 2. Mix magical command
+	//   mix.#Run & {
+	//    script: "mix phx.digest"
+	//    mix: {
+	//     env:        "prod"
+	//     app:        _appName
+	//     depsCache:  "private"
+	//     buildCache: "private"
+	//    }
+	//    workdir: _
+	//    // FIXME: remove copy-pasta
+	//    mounts: nodeModules: {
+	//     contents: engine.#CacheDir & {
+	//      // FIXME: do we need an ID here?
+	//      id: "\(mix.app)_assets_node_modules"
+	//      // FIXME: does this command need write access to node_modules cache?
+	//      concurrency: "private"
+	//     }
+	//     dest: "\(workdir)/node_modules"
+	//    }
+	//   },
+	//  ]
+	// }
+
+	// dev: {
+	// compile: mix.#Compile & {
+	//  env:    "dev"
+	//  app:    "thechangelog"
+	//  base:   inputs.params.runtimeImage
+	//  source: inputs.directories.app.contents
+	// }
+
+	// assets: docker.#Build & {
+	//  steps: [
+	//   // 1. Start from dev runtime build
+	//   {
+	//    output: build.output
+	//   },
+	//   // 2. Build web assets
+	//   mix.#Run & {
+	//    mix: {
+	//     env:        "dev"
+	//     app:        _appName
+	//     depsCache:  "private"
+	//     buildCache: "private"
+	//    }
+	//    // FIXME: move this to a reusable def (yarn package? or private?)
+	//    mounts: nodeModules: {
+	//     contents: engine.#CacheDir & {
+	//      // FIXME: do we need an ID here?
+	//      id: "\(mix.app)_assets_node_modules"
+	//      // FIXME: will there be multiple writers?
+	//      concurrency: "locked"
+	//     }
+	//     dest: "\(workdir)/node_modules"
+	//    }
+	//    // FIXME: run 'yarn install' and 'yarn run compile' separately, with different caching?
+	//    // FIXME: can we reuse universe.dagger.io/yarn ???? 0:-)
+	//    script:  "yarn install --frozen-lockfile && yarn run compile"
+	//    workdir: "/app/assets"
+	//   },
+	//  ]
+	// }
+	// }
+	// test: {
+	//  build: mix.#Build & {
+	//   env:    "test"
+	//   app:    _appName
+	//   base:   inputs.params.runtimeImage
+	//   source: inputs.directories.app.contents
+	//  }
+
+	//  // Run tests
+	//  run: docker.#Run & {
+	//   image:  build.output
+	//   script: "mix test"
+	//  }
+
+	//  db: {
+	//   // Pull test DB image
+	//   pull: docker.#Pull & {
+	//    source: inputs.params.test_db_image
+	//   }
+
+	//   // Run test DB
+	//   // FIXME: kill once no longer needed (when tests are done running)
+	//   run: docker.#Run & {
+	//    image: pull.output
+	//   }
+	//  }
+	// }
+}
diff --git a/pkg/universe.dagger.io/examples/changelog.com/elixir/mix/mix.cue b/pkg/universe.dagger.io/examples/changelog.com/elixir/mix/mix.cue
new file mode 100644
index 00000000..bd0b4358
--- /dev/null
+++ b/pkg/universe.dagger.io/examples/changelog.com/elixir/mix/mix.cue
@@ -0,0 +1,88 @@
+package mix
+
+import (
+	"dagger.io/dagger"
+	"dagger.io/dagger/engine"
+
+	"universe.dagger.io/docker"
+)
+
+#Get: #Run & {
+	// Applies to all environments
+	env: null
+	cache: {
+		build: null
+		deps:  "locked"
+	}
+	container: command: {
+		name: "sh"
+		flags: "-c": "mix do deps.compile, compile"
+	}
+}
+
+// Compile Elixir dependencies, including the app
+#Compile: #Run & {
+	cache: {
+		build: "locked"
+		deps:  "locked"
+	}
+	container: command: {
+		name: "sh"
+		flags: "-c": "mix do deps.compile, compile"
+	}
+}
+
+// Run mix task with all necessary mounts so compiled artefacts get cached
+// FIXME: add default image to hexpm/elixir:1.13.2-erlang-23.3.4.11-debian-bullseye-20210902
+#Run: {
+	app: {
+		// Application name
+		name: string
+
+		// Application source code
+		source: dagger.#FS
+	}
+
+	// Mix environment
+	env: string | null
+
+	// Configure mix caching
+	// FIXME: simpler interface, eg. "ro" | "rw"
+	cache: {
+		// Dependencies cache
+		deps: null | "locked"
+
+		// Build cache
+		build: null | "locked"
+	}
+
+	// Run mix in a docker container
+	container: docker.#Run & {
+		if env != null {
+			"env": MIX_ENV: env
+		}
+		workdir: mounts.app.dest
+		mounts: "app": {
+			contents: app.source
+			dest:     "/mix/app"
+		}
+		if cache.deps != null {
+			mounts: deps: {
+				contents: engine.#CacheDir & {
+					id:          "\(app.name)_deps"
+					concurrency: cache.deps
+				}
+				dest: "\(mounts.app.dest)/deps"
+			}
+		}
+		if cache.build != null {
+			mounts: buildCache: {
+				contents: engine.#CacheDir & {
+					id:          "\(app.name)_build_\(env)"
+					concurrency: cache.build
+				}
+				dest: "\(mounts.app.dest)/_build/\(env)"
+			}
+		}
+	}
+}
diff --git a/pkg/universe.dagger.io/examples/changelog.com/gerhard/gerhard.cue b/pkg/universe.dagger.io/examples/changelog.com/gerhard/gerhard.cue
new file mode 100644
index 00000000..466784d5
--- /dev/null
+++ b/pkg/universe.dagger.io/examples/changelog.com/gerhard/gerhard.cue
@@ -0,0 +1,9 @@
+package changelog
+
+import (
+	"dagger.io/dagger"
+)
+
+dagger.#Plan & {
+	inputs: directories: app: path: "/Users/gerhard/github.com/thechangelog/changelog.com/"
+}
diff --git a/pkg/universe.dagger.io/examples/changelog.com/highlevel/ci.cue b/pkg/universe.dagger.io/examples/changelog.com/highlevel/ci.cue
deleted file mode 100644
index 027b0b40..00000000
--- a/pkg/universe.dagger.io/examples/changelog.com/highlevel/ci.cue
+++ /dev/null
@@ -1,147 +0,0 @@
-package ci
-
-import (
-	"dagger.io/dagger"
-	"dagger.io/dagger/engine"
-
-	"universe.dagger.io/docker"
-	"universe.dagger.io/examples/changelog.com/highlevel/elixir/mix"
-)
-
-dagger.#Plan & {
-	// Receive things from client
-	inputs: {
-		directories: {
-			// App source code
-			app: _
-		}
-		secrets: {
-			// Docker ID password
-			docker: _
-		}
-		params: {
-			// Which Elixir base image to download
-			runtime_image: docker.#Ref | *"thechangelog/runtime:2021-05-29T10.17.12Z"
-			// Which test DB image to download
-			test_db_image: docker.#Ref | *"circleci/postgres:12.6"
-		}
-	}
-
-	// Do things
-	actions: {
-		// Reuse in all mix commands
-		_appName: "changelog"
-
-		prod: assets: docker.#Build & {
-			steps: [
-				// 1. Start from dev assets :)
-				dev.assets,
-				// 2. Mix magical command
-				mix.#Run & {
-					command: {
-						name: "mix"
-						args: ["phx.digest"]
-					}
-					mix: {
-						env:        "prod"
-						app:        _appName
-						depsCache:  "private"
-						buildCache: "private"
-					}
-					workdir: _
-					// FIXME: remove copy-pasta
-					mounts: nodeModules: {
-						contents: engine.#CacheDir & {
-							// FIXME: do we need an ID here?
-							id: "\(mix.app)_assets_node_modules"
-							// FIXME: does this command need write access to node_modules cache?
-							concurrency: "private"
-						}
-						dest: "\(workdir)/node_modules"
-					}
-				},
-			]
-		}
-
-		dev: {
-			build: mix.#Build & {
-				env:    "dev"
-				app:    "thechangelog"
-				base:   inputs.params.runtime_image
-				source: inputs.directories.app.contents
-			}
-
-			assets: docker.#Build & {
-				steps: [
-					// 1. Start from dev runtime build
-					{
-						output: build.output
-					},
-					// 2. Build web assets
-					mix.#Run & {
-						mix: {
-							env:        "dev"
-							app:        _appName
-							depsCache:  "private"
-							buildCache: "private"
-						}
-						// FIXME: move this to a reusable def (yarn package? or private?)
-						mounts: nodeModules: {
-							contents: engine.#CacheDir & {
-								// FIXME: do we need an ID here?
-								id: "\(mix.app)_assets_node_modules"
-								// FIXME: will there be multiple writers?
-								concurrency: "locked"
-							}
-							dest: "\(workdir)/node_modules"
-						}
-						// FIXME: run 'yarn install' and 'yarn run compile' separately, with different caching?
-						// FIXME: can we reuse universe.dagger.io/yarn ???? 0:-)
-						command: {
-							name: "sh"
-							flags: "-c": """
-								yarn install --frozen-lockfile && yarn run compile"
-								"""
-						}
-						workdir: "/app/assets"
-					},
-				]
-			}
-		}
-		test: {
-			build: mix.#Build & {
-				env:    "test"
-				app:    _appName
-				base:   inputs.params.runtime_image
-				source: inputs.directories.app.contents
-			}
-
-			// Run tests
-			run: docker.#Run & {
-				image: build.output
-				command: {
-					name: "mix"
-					args: ["test"]
-				}
-				// Don't cache running tests
-				// Just because we've tested a version before, doesn't mean we don't
-				// want to test it again.
-				// FIXME: make this configurable
-				always: true
-			}
-
-			db: {
-				// Pull test DB image
-				pull: docker.#Pull & {
-					source: inputs.params.test_db_image
-				}
-
-				// Run test DB
-				// FIXME: kill once no longer needed (when tests are done running)
-				run: docker.#Run & {
-					image: pull.output
-				}
-			}
-		}
-	}
-}
diff --git a/pkg/universe.dagger.io/examples/changelog.com/highlevel/elixir/mix/mix.cue b/pkg/universe.dagger.io/examples/changelog.com/highlevel/elixir/mix/mix.cue
deleted file mode 100644
index 81239de2..00000000
--- a/pkg/universe.dagger.io/examples/changelog.com/highlevel/elixir/mix/mix.cue
+++ /dev/null
@@ -1,101 +0,0 @@
-package mix
-
-import (
-	"dagger.io/dagger"
-	"dagger.io/dagger/engine"
-
-	"universe.dagger.io/docker"
-)
-
-// Build an Elixir application with Mix
-#Build: {
-	// Ref to base image
-	// FIXME: spin out docker.#Build for max flexibility
-	//   Perhaps implement as a custom docker.#Build step?
-	base: docker.#Ref
-
-	// App name (for cache scoping)
-	app: string
-
-	// Mix environment
-	env: string
-
-	// Application source code
-	source: dagger.#FS
-
-	docker.#Build & {
-		steps: [
-			// 1. Pull base image
-			docker.#Pull & {
-				source: base
-			},
-			// 2. Copy app source
-			docker.#Copy & {
-				contents: source
-				dest:     "/app"
-			},
-			// 3. Download dependencies into deps cache
-			#Run & {
-				mix: {
-					"env":     env
-					"app":     app
-					depsCache: "locked"
-				}
-				workdir: "/app"
-				command: {
-					name: "mix"
-					args: ["deps.get"]
-				}
-			},
-			// 4. Build!
-			// FIXME: step 5 is to add image data, see issue 1339
-			#Run & {
-				mix: {
-					"env":      env
-					"app":      app
-					depsCache:  "private"
-					buildCache: "locked"
-				}
-				workdir: "/app"
-				command: {
-					name: "mix"
-					args: ["do", "deps.compile,compile"]
-				}
-			},
-		]
-	}
-}
-
-// Run mix correctly in a container
-#Run: {
-	mix: {
-		app: string
-		env: string
-		// FIXME: "ro" | "rw"
-		depsCache?:  "private" | "locked"
-		buildCache?: "private" | "locked"
-	}
-	docker.#Run
-	env: MIX_ENV: mix.env
-	workdir: string
-	{
-		mix: depsCache: string
-		mounts: depsCache: {
-			contents: engine.#CacheDir & {
-				id:          "\(mix.app)_deps"
-				concurrency: mix.depsCache
-			}
-			dest: "\(workdir)/deps"
-		}
-	} | {}
-	{
-		mix: buildCache: string
-		mounts: buildCache: {
-			contents: engine.#CacheDir & {
-				id:          "\(mix.app)_deps"
-				concurrency: mix.buildCache
-			}
-			dest: "\(workdir)/deps"
-		}
-	} | {}
-}
diff --git a/pkg/universe.dagger.io/examples/changelog.com/highlevel/gerhard/config.cue b/pkg/universe.dagger.io/examples/changelog.com/highlevel/gerhard/config.cue
deleted file mode 100644
index edef63f7..00000000
--- a/pkg/universe.dagger.io/examples/changelog.com/highlevel/gerhard/config.cue
+++ /dev/null
@@ -1,3 +0,0 @@
-package ci
-
-inputs: directories: app: path: "/Users/gerhard/github.com/thechangelog/changelog.com/"
diff --git a/pkg/universe.dagger.io/examples/changelog.com/main.cue b/pkg/universe.dagger.io/examples/changelog.com/main.cue
new file mode 100644
index 00000000..bdcb4cfe
--- /dev/null
+++ b/pkg/universe.dagger.io/examples/changelog.com/main.cue
@@ -0,0 +1,83 @@
+package changelog
+
+import (
+	"dagger.io/dagger"
+
+	"universe.dagger.io/docker"
+	"universe.dagger.io/git"
+	"universe.dagger.io/examples/changelog.com/elixir/mix"
+)
+
+dagger.#Plan & {
+	// Receive things from client
+	inputs: {
+		directories: {
+			// App source code
+			app?: _
+		}
+		secrets: {
+			// Docker ID password
+			docker: _
+		}
+		params: {
+			app: {
+				// App name
+				name: string | *"changelog"
+
+				// Address of app base image
+				image: docker.#Ref | *"thechangelog/runtime:2021-05-29T10.17.12Z"
+			}
+
+			test: {
+				// Address of test db image
+				db: image: docker.#Ref | *"circleci/postgres:12.6"
+			}
+
+		}
+	}
+
+	// Do things
+	actions: {
+		app: {
+			name: inputs.params.app.name
+
+			// changelog.com source code
+			source: dagger.#FS
+			if inputs.directories.app != _|_ {
+				source: inputs.directories.app.contents
+			}
+			if inputs.directories.app == _|_ {
+				fetch: git.#Pull & {
+					remote: "https://github.com/thechangelog/changelog.com"
+					ref:    "master"
+				}
+				source: fetch.output
+			}
+
+			// Assemble base image
+			_pull: docker.#Pull & {
+				source: inputs.params.app.image
+			}
+			image: _pull.output
+
+			// Download Elixir dependencies
+			deps: mix.#Get & {
+				app: {
+					"name":   name
+					"source": source
+				}
+				container: "image": image
+			}
+
+			// Compile dev environment
+			dev: mix.#Compile & {
+				env: "dev"
+				app: {
+					"name":   name
+					"source": source
+				}
+				container: "image": image
+			}
+		}
+	}
+}