diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..2f7896d
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+target/
diff --git a/resolution.nu b/resolution.nu
new file mode 100644
index 0000000..6b64fe0
--- /dev/null
+++ b/resolution.nu
@@ -0,0 +1,91 @@
+const PACKAGE_FILE = "package.nuon"
+
+# NOTE: just to wait for 0.88 and `std null-device`
+def null-device []: nothing -> path {
+    "/dev/null"
+}
+
+# TODO: just to wait for 0.88 and built-in `mktemp`
+def mktemp [pattern: string, --tmpdir, --directory] {
+    ^mktemp -t -d $pattern
+}
+
+export def build [package: path, --target-directory: path = "target/"] {
+    let pkg_file = $package | path join $PACKAGE_FILE
+    if not ($pkg_file | path exists) {
+        error make {
+            msg: $"(ansi red_bold)not_a_package(ansi reset)",
+            label: {
+                text: "does not appear to be a package",
+                span: (metadata $package).span,
+            },
+            help: $"does not contain a `($PACKAGE_FILE)` file",
+        }
+    }
+
+    let pkg = open $pkg_file | get name
+    let target_directory = $target_directory | path expand
+
+    let head = mktemp --tmpdir --directory nupm_install_XXXXXXX
+    ^git worktree add --detach $head HEAD out+err> (null-device)
+    rm --recursive ($head | path join ".git")
+    ^git worktree prune out+err> (null-device)
+
+    let target = $target_directory | path join $pkg (^git rev-parse HEAD)
+    if ($target | path exists) {
+        rm --recursive $target
+    }
+    mkdir $target
+
+    let package_files = $head | path join $package $pkg
+    cp --recursive $package_files ($target | path join "pkg")
+
+    let activation = $"export-env {
+        $env.NU_LIB_DIRS = \($env.NU_LIB_DIRS? | default [] | prepend ($target)\)
+    }"
+    $activation | save --force ($target | path join "activate.nu")
+}
+
+export def run [package: path, --target-directory: path = "target/"] {
+    let pkg_file = $package | path join $PACKAGE_FILE
+    if not ($pkg_file | path exists) {
+        error make {
+            msg: $"(ansi red_bold)not_a_package(ansi reset)",
+            label: {
+                text: "does not appear to be a package",
+                span: (metadata $package).span,
+            },
+            help: $"does not contain a `($PACKAGE_FILE)` file",
+        }
+    }
+
+    let pkg = open $pkg_file | get name
+    let target_directory = $target_directory | path expand
+
+    let config_file = $nu.temp-path | path join config.nu
+    let env_file = $nu.temp-path | path join env.nu
+
+    let activation_file = $target_directory | path join $pkg (^git rev-parse HEAD) "activate.nu"
+    if not ($activation_file | path exists) {
+        error make {
+            msg: $"(ansi red_bold)package_not_built(ansi reset)",
+            label: {
+                text: "does not appear to be built",
+                span: (metadata $package).span,
+            },
+            help: $"could not find `($activation_file)`",
+        }
+    }
+
+    $"overlay use ($activation_file)" | save --force $env_file
+    "$env.config.show_banner = false" | save --force $config_file
+
+    ^$nu.current-exe [
+        --config $config_file
+        --env-config $env_file
+        --execute $"
+            $env.PROMPT_COMMAND = '($pkg)'
+            use ($package | path join $pkg)
+        "
+    ]
+}
diff --git a/tests/packages/spam_resolution/package.nuon b/tests/packages/spam_resolution/package.nuon
new file mode 100644
index 0000000..6b96569
--- /dev/null
+++ b/tests/packages/spam_resolution/package.nuon
@@ -0,0 +1,3 @@
+{
+    name: "spam_resolution"
+}
diff --git a/tests/packages/spam_resolution/spam_resolution/lib/bar.nu b/tests/packages/spam_resolution/spam_resolution/lib/bar.nu
new file mode 100644
index 0000000..7365572
--- /dev/null
+++ b/tests/packages/spam_resolution/spam_resolution/lib/bar.nu
@@ -0,0 +1,6 @@
+use lib
+
+export def main [] {
+    print "this is bar"
+    lib
+}
diff --git a/tests/packages/spam_resolution/spam_resolution/lib/internal.nu b/tests/packages/spam_resolution/spam_resolution/lib/internal.nu
new file mode 100644
index 0000000..e5914b0
--- /dev/null
+++ b/tests/packages/spam_resolution/spam_resolution/lib/internal.nu
@@ -0,0 +1,3 @@
+export def yeah [] {
+    print "this is yeah"
+}
diff --git a/tests/packages/spam_resolution/spam_resolution/lib/lib.nu b/tests/packages/spam_resolution/spam_resolution/lib/lib.nu
new file mode 100644
index 0000000..a401f96
--- /dev/null
+++ b/tests/packages/spam_resolution/spam_resolution/lib/lib.nu
@@ -0,0 +1,3 @@
+export def main [] {
+    print "this is lib"
+}
diff --git a/tests/packages/spam_resolution/spam_resolution/mod.nu b/tests/packages/spam_resolution/spam_resolution/mod.nu
new file mode 100644
index 0000000..660c5a2
--- /dev/null
+++ b/tests/packages/spam_resolution/spam_resolution/mod.nu
@@ -0,0 +1,10 @@
+module pkg/lib/lib.nu                # allow to `use lib` in the whole module
+export module pkg/lib/bar.nu         # re-export a submodule named `bar`
+export use pkg/lib/internal.nu yeah  # re-export an internal command named `yeah`
+
+use lib
+
+export def main [] {
+    print "this is foo"
+    lib
+}