refactor(build): eliminate dedicated output directories

.gitignore

@@ -1,6 +1,5 @@
 # MoonBit build artifacts
 _build/
-target/
 .mooncakes/
 .repos/
 dist/

AGENTS.md

@@ -65,8 +65,8 @@ developer must perform them.
   aligned with the actual examples.
 - `proton/prebuilt/<platform>/`: shipped Proton-only native artifacts. Do not
   put CEF runtime files here.
-- `lib/`, `build/`, `_build/`, `target/`, `native/build*`, `native/dist/`:
-  generated or vendored artifacts.
+- `lib/`, `build/`, `_build/`, `native/build*`, `native/dist/`: generated or
+  vendored artifacts. Packaged application artifacts are written to `dist/`.
 - `.proton/`: generated project runtime cache created by `proton_cli cef setup`.
 
 ## Build And Test

README.md

@@ -414,7 +414,7 @@ default targets and output directory:
         "role": "Editor"
       }
     ],
-    "output": "target/proton-dist"
+    "output": "dist"
   }
 }
 ```
@@ -439,7 +439,7 @@ proton_cli package --release
 
 The package command performs a debug build by default. Pass `--release` to use
 MoonBit's release build mode, or `--no-build` to reuse an existing build from
-the selected mode. Package output is written to `target/proton-dist` by default.
+the selected mode. Package output is written to `dist` by default.
 Icons, resources, output targets, signing, notarization, custom URL schemes, and
 macOS document types are configured through `proton.project.json` and package command
 options.

cli/build_cmd/build_wbtest.mbt

@@ -25,9 +25,6 @@ async fn[T] expect_build_config_error(
 
 ///|
 fn ensure_build_test_dir(path : String) -> Unit {
-  @mbfs.create_dir("target") catch {
-    _ => ()
-  }
   @mbfs.create_dir(path) catch {
     _ => ()
   }
@@ -101,9 +98,9 @@ test "parse build args package and config" {
 ///|
 test "parse build args accepts an isolated Moon target directory" {
   let raw = parse_build_args([
-    "--package", "app", "--moon-target-dir", "target/build-app",
+    "--package", "app", "--moon-target-dir", "custom-build",
   ])
-  @debug.assert_eq(raw.moon_target_dir, Some("target/build-app"))
+  @debug.assert_eq(raw.moon_target_dir, Some("custom-build"))
 }
 
 ///|
@@ -146,19 +143,18 @@ test "moon build args prepend an isolated target directory" {
     moon_build_args_with_target_dir(
       "app",
       ["--diagnostic-limit", "80"],
-      Some("target/build-app"),
+      Some("custom-build"),
     ),
     [
-      "--target-dir", "target/build-app", "build", "app", "--diagnostic-limit", "80",
+      "--target-dir", "custom-build", "build", "app", "--diagnostic-limit", "80",
       "--target", "native",
     ],
   )
 }
 
 ///|
 async test "frontend path validation reports missing directory" {
-  let root = "target/proton-build-cwd"
-  ensure_build_test_dir(root)
+  let root = @async_fs.tmpdir(prefix="proton-build-cwd-")
   let error = try
     resolve_frontend_path(root, Some("missing"), "npm run build")
   catch {
@@ -172,8 +168,7 @@ async test "frontend path validation reports missing directory" {
 
 ///|
 async test "backend path supports nested directories with spaces" {
-  let root = "target/proton build backend"
-  ensure_build_test_dir(root)
+  let root = @async_fs.tmpdir(prefix="proton-build-backend-")
   ensure_build_test_dir(@fsutil.path_join(root, "nested"))
   ensure_build_test_dir(@fsutil.path_join(root, "nested/backend app"))
   let path = resolve_backend_path(root, Some("nested/backend app"))
@@ -182,8 +177,7 @@ async test "backend path supports nested directories with spaces" {
 
 ///|
 async test "build config discovery prefers package-local proton.project.json" {
-  let root = "target/proton-build-package-config"
-  ensure_build_test_dir(root)
+  let root = @async_fs.tmpdir(prefix="proton-build-config-")
   ensure_build_test_dir(@fsutil.path_join(root, "desktop"))
   let package_config = @fsutil.path_join(
     @fsutil.path_join(root, "desktop"),
@@ -201,9 +195,8 @@ async test "build config discovery prefers package-local proton.project.json" {
 ///|
 async test "resolve path accepts Windows backslash relative input" {
   if @path.sep == '\\' {
-    let dir = "target/proton-build-path"
-    ensure_build_test_dir(dir)
-    let resolved = @fsutil.resolve_path(".", "target\\proton-build-path")
+    let dir = @async_fs.tmpdir(prefix="proton-build-path-")
+    let resolved = @fsutil.resolve_path(".", dir.replace_all(old="/", new="\\"))
     assert_true(resolved.contains(":/") || resolved.contains(":\\"))
     assert_true(@fsutil.path_exists(resolved))
     let absolute = resolved.replace_all(old="/", new="\\")
@@ -213,8 +206,7 @@ async test "resolve path accepts Windows backslash relative input" {
 
 ///|
 async test "project config validation rejects unknown top-level fields" {
-  let dir = "target/proton-build-config"
-  ensure_build_test_dir(dir)
+  let dir = @async_fs.tmpdir(prefix="proton-build-config-")
   let path = @fsutil.path_join(dir, "unknown.proton.project.json")
   write_build_test_file(path, build_config_with("legacy_runtime", true))
   let error = expect_build_config_error(() => read_project_config(path))
@@ -231,8 +223,7 @@ async test "project config validation rejects unknown top-level fields" {
 
 ///|
 async test "project config validation requires window" {
-  let dir = "target/proton-build-config"
-  ensure_build_test_dir(dir)
+  let dir = @async_fs.tmpdir(prefix="proton-build-config-")
   let path = @fsutil.path_join(dir, "missing-window.proton.project.json")
   write_build_test_file(
     path,
@@ -259,8 +250,7 @@ async test "project config validation requires window" {
 
 ///|
 async test "project config validation rejects unsupported size_hint" {
-  let dir = "target/proton-build-config"
-  ensure_build_test_dir(dir)
+  let dir = @async_fs.tmpdir(prefix="proton-build-config-")
   let path = @fsutil.path_join(dir, "bad-size-hint.proton.project.json")
   write_build_test_file(
     path,
@@ -294,18 +284,18 @@ async test "project config validation rejects unsupported size_hint" {
 
 ///|
 async test "project config parsing keeps active bundle metadata out of build validation" {
-  let dir = "target/proton-build-config"
-  ensure_build_test_dir(dir)
+  let dir = @async_fs.tmpdir(prefix="proton-build-config-")
   let path = @fsutil.path_join(dir, "active-bundle.proton.project.json")
   write_build_test_file(path, build_config_with("bundle", { "active": true }))
   ignore(read_project_config(path))
 }
 
 ///|
 async test "production entry validation requires file-backed entry" {
+  let dir = @async_fs.tmpdir(prefix="proton-build-entry-")
   let error = try
     validate_production_entry_file(
-      @proton_config.ProjectEntry::Asset("target/proton-build-missing.html"),
+      @proton_config.ProjectEntry::Asset(@fsutil.path_join(dir, "missing.html")),
     )
   catch {
     BuildPathError::Missing(..) as error => error.message()
@@ -314,8 +304,6 @@ async test "production entry validation requires file-backed entry" {
     _ => fail("expected build error")
   }
   assert_true(error.contains("production entry does not exist"))
-  let dir = "target/proton-build-entry"
-  ensure_build_test_dir(dir)
   let file = @fsutil.path_join(dir, "index.html")
   @mbfs.write_string_to_file(file, "<!doctype html>", encoding="utf8") catch {
     err => abort(@debug.render(Repr(err)))
@@ -325,8 +313,7 @@ async test "production entry validation requires file-backed entry" {
 
 ///|
 async test "release validation checks secondary window entry files" {
-  let dir = "target/proton-build-secondary-entry"
-  ensure_build_test_dir(dir)
+  let dir = @async_fs.tmpdir(prefix="proton-build-secondary-")
   let main = @fsutil.path_join(dir, "main.html")
   let missing = @fsutil.path_join(dir, "secondary/missing.html")
   write_build_test_file(main, "<!doctype html>")
@@ -354,7 +341,7 @@ async test "release validation checks secondary window entry files" {
 test "frontend release rejects url production entry" {
   let frontend = Some(
     @proton_config.ProjectFrontendConfig::new(
-      dist=Some("target/proton-build-entry"),
+      dist=Some("fixtures/frontend-dist"),
     ),
   )
   let error = expect_build_error_message(() => {
@@ -374,7 +361,7 @@ test "frontend release config preflight rejects url entry" {
     backend: None,
     frontend: Some(
       @proton_config.ProjectFrontendConfig::new(
-        dist=Some("target/proton-build-entry"),
+        dist=Some("fixtures/frontend-dist"),
       ),
     ),
   }
@@ -387,7 +374,7 @@ test "frontend release requires dist" {
   let config = BuildProjectConfig::{
     base_dir: ".",
     entries: [
-      @proton_config.ProjectEntry::Asset("target/proton-build-entry/index.html"),
+      @proton_config.ProjectEntry::Asset("fixtures/frontend-dist/index.html"),
     ],
     backend: None,
     frontend: Some(
@@ -402,8 +389,7 @@ test "frontend release requires dist" {
 
 ///|
 async test "production entry validation rejects directories" {
-  let dir = "target/proton-build-entry-dir"
-  ensure_build_test_dir(dir)
+  let dir = @async_fs.tmpdir(prefix="proton-build-entry-dir-")
   let error = try
     validate_production_entry_file(@proton_config.ProjectEntry::Asset(dir))
   catch {

cli/cef/cef_platform_wbtest.mbt

@@ -75,7 +75,7 @@ test "runtime manifests separate portable and active metadata" {
 
 ///|
 test "CEF cache paths are absolute and scoped by platform and archive" {
-  let project_root = @fsutil.resolve_path(".", "target/proton-cache-project")
+  let project_root = @fsutil.resolve_path(".", "fixtures/proton-cache-project")
   let home = @fsutil.resolve_path(project_root, "../proton-cache-home")
   let cache_root = resolve_global_cef_cache_root(
     project_root~,
@@ -97,7 +97,7 @@ test "CEF cache paths are absolute and scoped by platform and archive" {
 
 ///|
 test "relative CEF cache overrides resolve from the project root" {
-  let project_root = @fsutil.resolve_path(".", "target/proton-cache-project")
+  let project_root = @fsutil.resolve_path(".", "fixtures/proton-cache-project")
   let actual = resolve_global_cef_cache_root(
     project_root~,
     configured_root=Some("../shared-cef"),
@@ -116,10 +116,9 @@ test "relative CEF cache overrides resolve from the project root" {
 
 ///|
 async test "runtime metadata does not persist the active CEF cache path" {
-  let root = @fsutil.resolve_path(".", "target/proton-runtime-manifest")
+  let root = @async_fs.tmpdir(prefix="proton-runtime-manifest-")
   let proton_dir = @fsutil.path_join(root, ".proton")
   let runtime_dir = @fsutil.path_join(proton_dir, "runtime")
-  remove_tree(root)
   ensure_dir(runtime_dir)
   let cef_root = @fsutil.resolve_path(
     root, "../shared-cef/darwin-arm64/cef-test",
@@ -306,8 +305,8 @@ test "generated runtime directories must stay under the project root" {
 
 ///|
 test "CEF installation never removes a project boundary or filesystem root" {
-  let root = @fsutil.resolve_path(".", "target/proton-cef-project")
-  let cache = @fsutil.resolve_path(".", "target/proton-cef-cache/runtime")
+  let root = @fsutil.resolve_path(".", "fixtures/proton-cef-project")
+  let cache = @fsutil.resolve_path(".", "fixtures/proton-cef-cache/runtime")
   assert_safe_install_dir(cache, root)
   let parent = @fsutil.path_parent(root)
   let mut filesystem_root = root

cli/dev/dev_wbtest.mbt

@@ -5,9 +5,6 @@ fn parse_dev_args(args : Array[String]) -> RawDevOptions raise {
 
 ///|
 fn ensure_dev_test_dir(path : String) -> Unit {
-  @mbfs.create_dir("target") catch {
-    _ => ()
-  }
   @mbfs.create_dir(path) catch {
     _ => ()
   }
@@ -79,15 +76,14 @@ test "parse dev args package and frontend overrides" {
 ///|
 test "parse dev args accepts an isolated Moon target directory" {
   let raw = parse_dev_args([
-    "--package", "desktop", "--moon-target-dir", "target/dev-app",
+    "--package", "desktop", "--moon-target-dir", "custom-dev-build",
   ])
-  @debug.assert_eq(raw.moon_target_dir, Some("target/dev-app"))
+  @debug.assert_eq(raw.moon_target_dir, Some("custom-dev-build"))
 }
 
 ///|
 async test "read dev project config extracts module paths" {
-  let dir = "target/proton-dev-config"
-  ensure_dev_test_dir(dir)
+  let dir = @async_fs.tmpdir(prefix="proton-dev-config-")
   let path = @fsutil.path_join(dir, "proton.project.json")
   @mbfs.write_string_to_file(
     path,
@@ -129,8 +125,7 @@ async test "read dev project config extracts module paths" {
 
 ///|
 async test "read dev frontend config validates full project config" {
-  let dir = "target/proton-dev-config"
-  ensure_dev_test_dir(dir)
+  let dir = @async_fs.tmpdir(prefix="proton-dev-config-")
   let path = @fsutil.path_join(dir, "bad-size-hint.proton.project.json")
   @mbfs.write_string_to_file(
     path,
@@ -171,8 +166,7 @@ async test "read dev frontend config validates full project config" {
 
 ///|
 async test "frontend path is validated only when frontend starts" {
-  let root = "target/proton-dev-cwd"
-  ensure_dev_test_dir(root)
+  let root = @async_fs.tmpdir(prefix="proton-dev-cwd-")
   ensure_dev_test_dir(@fsutil.path_join(root, "frontend"))
   let resolved = resolve_frontend_path(
     root,
@@ -206,8 +200,7 @@ async test "frontend path is validated only when frontend starts" {
 
 ///|
 async test "dev config discovery prefers package-local proton.project.json" {
-  let root = "target/proton-dev-package-config"
-  ensure_dev_test_dir(root)
+  let root = @async_fs.tmpdir(prefix="proton-dev-config-")
   ensure_dev_test_dir(@fsutil.path_join(root, "desktop"))
   let package_config = @fsutil.path_join(
     @fsutil.path_join(root, "desktop"),
@@ -226,9 +219,8 @@ async test "dev config discovery prefers package-local proton.project.json" {
 
 ///|
 async test "backend path supports nested directories with spaces" {
-  let root = "target/proton dev backend"
+  let root = @async_fs.tmpdir(prefix="proton-dev-backend-")
   let backend = @fsutil.path_join(root, "modules/backend app")
-  ensure_dev_test_dir(root)
   ensure_dev_test_dir(@fsutil.path_join(root, "modules"))
   ensure_dev_test_dir(backend)
   let resolved = resolve_backend_path(root, Some("modules/backend app"))
@@ -237,7 +229,7 @@ async test "backend path supports nested directories with spaces" {
 
 ///|
 async test "dev runtime layout validates helper" {
-  let root = "target/proton-dev-runtime-layout"
+  let root = @async_fs.tmpdir(prefix="proton-dev-runtime-")
   let runtime = create_fake_dev_runtime(root)
   let loaded = dev_runtime_from_root(
     @fsutil.resolve_path(".", runtime),
@@ -277,7 +269,7 @@ async test "dev runtime layout validates helper" {
 
 ///|
 async test "dev process preloads an indirect Linux CEF runtime" {
-  let root = "target/proton-dev-runtime-preload"
+  let root = @async_fs.tmpdir(prefix="proton-dev-preload-")
   let runtime_path = create_fake_dev_runtime(root)
   let runtime = dev_runtime_from_root(
     @fsutil.resolve_path(".", runtime_path),
@@ -377,7 +369,7 @@ test "dev app spawn env replaces inherited Windows variable spellings" {
 
 ///|
 async test "read dev runtime honors PROTON_NATIVE_DIST override" {
-  let root = "target/proton-dev-runtime-env"
+  let root = @async_fs.tmpdir(prefix="proton-dev-runtime-env-")
   let runtime = create_fake_dev_runtime(root)
   let previous = @env.get_env_var("PROTON_NATIVE_DIST")
   defer (match previous {
@@ -396,7 +388,7 @@ async test "read dev runtime honors PROTON_NATIVE_DIST override" {
       @fsutil.path_join(loaded.bin_dir, helper_executable_name()),
     ),
   )
-  let bad_root = "target/proton-dev-runtime-bad-env"
+  let bad_root = @fsutil.path_join(root, "bad")
   ensure_dev_test_dir(bad_root)
   @env.set_env_var("PROTON_NATIVE_DIST", "missing-runtime")
   try ensure_dev_runtime(@fsutil.resolve_path(".", bad_root), true) catch {
@@ -413,9 +405,8 @@ async test "read dev runtime honors PROTON_NATIVE_DIST override" {
 ///|
 async test "resolve path accepts Windows backslash relative input" {
   if @path.sep == '\\' {
-    let dir = "target/proton-dev-path"
-    ensure_dev_test_dir(dir)
-    let resolved = @fsutil.resolve_path(".", "target\\proton-dev-path")
+    let dir = @async_fs.tmpdir(prefix="proton-dev-path-")
+    let resolved = @fsutil.resolve_path(".", dir.replace_all(old="/", new="\\"))
     assert_true(resolved.contains(":/") || resolved.contains(":\\"))
     assert_true(@fsutil.path_exists(resolved))
     let absolute = resolved.replace_all(old="/", new="\\")
@@ -510,8 +501,7 @@ async test "ready path validates curl probe availability" {
 ///|
 #cfg(not(platform="windows"))
 async test "frontend cancellation terminates child processes" {
-  let dir = "target/proton-dev-cancel-tree"
-  ensure_dev_test_dir(dir)
+  let dir = @async_fs.tmpdir(prefix="proton-dev-cancel-")
   let pid_path = @fsutil.path_join(dir, "child.pid")
   @mbfs.remove_file(pid_path) catch {
     _ => ()