Add PEP 723 support to uv run (#4656)

Closes #3096 

## Summary

Enables `uv run foo.py` to execute PEP 723-compatible scripts.

For example, given:

```python
# /// script
# requires-python = ">=3.11"
# dependencies = [
#   "requests<3",
#   "rich",
# ]
# ///

import requests
from rich.pretty import pprint

resp = requests.get("https://peps.python.org/api/peps.json")
data = resp.json()
pprint([(k, v["title"]) for k, v in data.items()][:10])
```

![Screenshot 2024-06-29 at 7 23
52 PM](c60f2415-4874-4b15-b9f5-dd8c8c35382e)

Cargo.lock

@@ -2074,9 +2074,9 @@ dependencies = [
 
 [[package]]
 name = "memchr"
-version = "2.7.2"
+version = "2.7.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6c8640c5d730cb13ebd907d8d04b52f55ac9a2eec55b440c8892f40d56c76c1d"
+checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
 
 [[package]]
 name = "memmap2"
@@ -4486,6 +4486,7 @@ dependencies = [
  "uv-normalize",
  "uv-requirements",
  "uv-resolver",
+ "uv-scripts",
  "uv-settings",
  "uv-tool",
  "uv-toolchain",
@@ -4979,6 +4980,22 @@ dependencies = [
  "uv-warnings",
 ]
 
+[[package]]
+name = "uv-scripts"
+version = "0.0.1"
+dependencies = [
+ "fs-err",
+ "indoc",
+ "memchr",
+ "once_cell",
+ "pep440_rs",
+ "pep508_rs",
+ "pypi-types",
+ "serde",
+ "thiserror",
+ "toml",
+]
+
 [[package]]
 name = "uv-settings"
 version = "0.0.1"

Cargo.toml

@@ -43,6 +43,7 @@ uv-macros = { path = "crates/uv-macros" }
 uv-normalize = { path = "crates/uv-normalize" }
 uv-requirements = { path = "crates/uv-requirements" }
 uv-resolver = { path = "crates/uv-resolver" }
+uv-scripts = { path = "crates/uv-scripts" }
 uv-settings = { path = "crates/uv-settings" }
 uv-state = { path = "crates/uv-state" }
 uv-tool = { path = "crates/uv-tool" }
@@ -94,6 +95,7 @@ itertools = { version = "0.13.0" }
 junction = { version = "1.0.0" }
 mailparse = { version = "0.15.0" }
 md-5 = { version = "0.10.6" }
+memchr = { version = "2.7.4" }
 miette = { version = "7.2.0" }
 nanoid = { version = "0.4.0" }
 once_cell = { version = "1.19.0" }

crates/uv-requirements/src/specification.rs

@@ -321,4 +321,15 @@ impl RequirementsSpecification {
     ) -> Result<Self> {
         Self::from_sources(requirements, &[], &[], client_builder).await
     }
+
+    /// Initialize a [`RequirementsSpecification`] from a list of [`Requirement`].
+    pub fn from_requirements(requirements: Vec<Requirement>) -> Self {
+        Self {
+            requirements: requirements
+                .into_iter()
+                .map(UnresolvedRequirementSpecification::from)
+                .collect(),
+            ..Self::default()
+        }
+    }
 }

crates/uv-scripts/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name = "uv-scripts"
+version = "0.0.1"
+edition = "2021"
+description = "Parse PEP 723-style Python scripts."
+
+[lints]
+workspace = true
+
+[dependencies]
+pep440_rs = { workspace = true }
+pep508_rs = { workspace = true }
+pypi-types = { workspace = true }
+
+fs-err = { workspace = true, features = ["tokio"] }
+memchr = { workspace = true }
+once_cell = { workspace = true }
+serde = { workspace = true, features = ["derive"] }
+thiserror = { workspace = true }
+toml = { workspace = true }
+
+[dev-dependencies]
+indoc = { workspace = true }

crates/uv-scripts/src/lib.rs

@@ -0,0 +1,283 @@
+use std::io;
+use std::path::Path;
+
+use memchr::memmem::Finder;
+use once_cell::sync::Lazy;
+use pypi_types::VerbatimParsedUrl;
+use serde::{Deserialize, Serialize};
+use thiserror::Error;
+
+static FINDER: Lazy<Finder> = Lazy::new(|| Finder::new(b"# /// script"));
+
+/// PEP 723 metadata as parsed from a `script` comment block.
+///
+/// See: <https://peps.python.org/pep-0723/>
+#[derive(Debug, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub struct Pep723Metadata {
+    pub dependencies: Vec<pep508_rs::Requirement<VerbatimParsedUrl>>,
+    pub requires_python: Option<pep440_rs::VersionSpecifiers>,
+}
+
+#[derive(Debug, Error)]
+pub enum Pep723Error {
+    #[error(transparent)]
+    Io(#[from] io::Error),
+    #[error(transparent)]
+    Utf8(#[from] std::str::Utf8Error),
+    #[error(transparent)]
+    Toml(#[from] toml::de::Error),
+}
+
+/// Read the PEP 723 `script` metadata from a Python file, if it exists.
+///
+/// See: <https://peps.python.org/pep-0723/>
+pub async fn read_pep723_metadata(
+    file: impl AsRef<Path>,
+) -> Result<Option<Pep723Metadata>, Pep723Error> {
+    let contents = match fs_err::tokio::read(file).await {
+        Ok(contents) => contents,
+        Err(err) if err.kind() == io::ErrorKind::NotFound => return Ok(None),
+        Err(err) => return Err(err.into()),
+    };
+
+    // Extract the `script` tag.
+    let Some(contents) = extract_script_tag(&contents)? else {
+        return Ok(None);
+    };
+
+    // Parse the metadata.
+    let metadata = toml::from_str(&contents)?;
+
+    Ok(Some(metadata))
+}
+
+/// Given the contents of a Python file, extract the `script` metadata block, with leading comment
+/// hashes removed.
+///
+/// See: <https://peps.python.org/pep-0723/>
+fn extract_script_tag(contents: &[u8]) -> Result<Option<String>, Pep723Error> {
+    // Identify the opening pragma.
+    let Some(index) = FINDER.find(contents) else {
+        return Ok(None);
+    };
+
+    // The opening pragma must be the first line, or immediately preceded by a newline.
+    if !(index == 0 || matches!(contents[index - 1], b'\r' | b'\n')) {
+        return Ok(None);
+    }
+
+    // Decode as UTF-8.
+    let contents = &contents[index..];
+    let contents = std::str::from_utf8(contents)?;
+
+    let mut lines = contents.lines();
+
+    // Ensure that the first line is exactly `# /// script`.
+    if !lines.next().is_some_and(|line| line == "# /// script") {
+        return Ok(None);
+    }
+
+    // > Every line between these two lines (# /// TYPE and # ///) MUST be a comment starting
+    // > with #. If there are characters after the # then the first character MUST be a space. The
+    // > embedded content is formed by taking away the first two characters of each line if the
+    // > second character is a space, otherwise just the first character (which means the line
+    // > consists of only a single #).
+    let mut toml = vec![];
+    for line in lines {
+        // Remove the leading `#`.
+        let Some(line) = line.strip_prefix('#') else {
+            break;
+        };
+
+        // If the line is empty, continue.
+        if line.is_empty() {
+            toml.push("");
+            continue;
+        }
+
+        // Otherwise, the line _must_ start with ` `.
+        let Some(line) = line.strip_prefix(' ') else {
+            break;
+        };
+        toml.push(line);
+    }
+
+    // Find the closing `# ///`. The precedence is such that we need to identify the _last_ such
+    // line.
+    //
+    // For example, given:
+    // ```python
+    // # /// script
+    // #
+    // # ///
+    // #
+    // # ///
+    // ```
+    //
+    // The latter `///` is the closing pragma
+    let Some(index) = toml.iter().rev().position(|line| *line == "///") else {
+        return Ok(None);
+    };
+    let index = toml.len() - index;
+
+    // Discard any lines after the closing `# ///`.
+    //
+    // For example, given:
+    // ```python
+    // # /// script
+    // #
+    // # ///
+    // #
+    // #
+    // ```
+    //
+    // We need to discard the last two lines.
+    toml.truncate(index - 1);
+
+    // Join the lines into a single string.
+    let toml = toml.join("\n") + "\n";
+
+    Ok(Some(toml))
+}
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn missing_space() {
+        let contents = indoc::indoc! {r"
+            # /// script
+            #requires-python = '>=3.11'
+            # ///
+        "};
+
+        assert_eq!(
+            super::extract_script_tag(contents.as_bytes()).unwrap(),
+            None
+        );
+    }
+
+    #[test]
+    fn no_closing_pragma() {
+        let contents = indoc::indoc! {r"
+            # /// script
+            # requires-python = '>=3.11'
+            # dependencies = [
+            #   'requests<3',
+            #   'rich',
+            # ]
+        "};
+
+        assert_eq!(
+            super::extract_script_tag(contents.as_bytes()).unwrap(),
+            None
+        );
+    }
+
+    #[test]
+    fn leading_content() {
+        let contents = indoc::indoc! {r"
+            pass # /// script
+            # requires-python = '>=3.11'
+            # dependencies = [
+            #   'requests<3',
+            #   'rich',
+            # ]
+            # ///
+            #
+            #
+        "};
+
+        assert_eq!(
+            super::extract_script_tag(contents.as_bytes()).unwrap(),
+            None
+        );
+    }
+
+    #[test]
+    fn simple() {
+        let contents = indoc::indoc! {r"
+            # /// script
+            # requires-python = '>=3.11'
+            # dependencies = [
+            #   'requests<3',
+            #   'rich',
+            # ]
+            # ///
+        "};
+
+        let expected = indoc::indoc! {r"
+            requires-python = '>=3.11'
+            dependencies = [
+              'requests<3',
+              'rich',
+            ]
+        "};
+
+        let actual = super::extract_script_tag(contents.as_bytes())
+            .unwrap()
+            .unwrap();
+
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn embedded_comment() {
+        let contents = indoc::indoc! {r"
+            # /// script
+            # embedded-csharp = '''
+            # /// <summary>
+            # /// text
+            # ///
+            # /// </summary>
+            # public class MyClass { }
+            # '''
+            # ///
+        "};
+
+        let expected = indoc::indoc! {r"
+            embedded-csharp = '''
+            /// <summary>
+            /// text
+            ///
+            /// </summary>
+            public class MyClass { }
+            '''
+        "};
+
+        let actual = super::extract_script_tag(contents.as_bytes())
+            .unwrap()
+            .unwrap();
+
+        assert_eq!(actual, expected);
+    }
+
+    #[test]
+    fn trailing_lines() {
+        let contents = indoc::indoc! {r"
+            # /// script
+            # requires-python = '>=3.11'
+            # dependencies = [
+            #   'requests<3',
+            #   'rich',
+            # ]
+            # ///
+            #
+            #
+        "};
+
+        let expected = indoc::indoc! {r"
+            requires-python = '>=3.11'
+            dependencies = [
+              'requests<3',
+              'rich',
+            ]
+        "};
+
+        let actual = super::extract_script_tag(contents.as_bytes())
+            .unwrap()
+            .unwrap();
+
+        assert_eq!(actual, expected);
+    }
+}

crates/uv/Cargo.toml

@@ -33,9 +33,10 @@ uv-installer = { workspace = true }
 uv-normalize = { workspace = true }
 uv-requirements = { workspace = true }
 uv-resolver = { workspace = true }
+uv-scripts = { workspace = true }
 uv-settings = { workspace = true, features = ["schemars"] }
-uv-toolchain = { workspace = true, features = ["schemars"]}
 uv-tool = { workspace = true }
+uv-toolchain = { workspace = true, features = ["schemars"]}
 uv-types = { workspace = true }
 uv-virtualenv = { workspace = true }
 uv-warnings = { workspace = true }

crates/uv/src/commands/project/mod.rs

@@ -15,7 +15,7 @@ use uv_distribution::Workspace;
 use uv_fs::Simplified;
 use uv_git::GitResolver;
 use uv_installer::{SatisfiesResult, SitePackages};
-use uv_requirements::{RequirementsSource, RequirementsSpecification};
+use uv_requirements::RequirementsSpecification;
 use uv_resolver::{FlatIndex, InMemoryIndex, OptionsBuilder, PythonRequirement, RequiresPython};
 use uv_toolchain::{
     request_from_version_file, EnvironmentPreference, Interpreter, PythonEnvironment, Toolchain,
@@ -280,7 +280,7 @@ pub(crate) async fn init_environment(
 /// Update a [`PythonEnvironment`] to satisfy a set of [`RequirementsSource`]s.
 pub(crate) async fn update_environment(
     venv: PythonEnvironment,
-    requirements: &[RequirementsSource],
+    spec: RequirementsSpecification,
     settings: &ResolverInstallerSettings,
     preview: PreviewMode,
     connectivity: Connectivity,
@@ -305,17 +305,6 @@ pub(crate) async fn update_environment(
         build_options,
     } = settings;
 
-    let client_builder = BaseClientBuilder::new()
-        .connectivity(connectivity)
-        .native_tls(native_tls)
-        .keyring(*keyring_provider);
-
-    // Read all requirements from the provided sources.
-    // TODO(zanieb): Consider allowing constraints and extras
-    // TODO(zanieb): Allow specifying extras somehow
-    let spec =
-        RequirementsSpecification::from_sources(requirements, &[], &[], &client_builder).await?;
-
     // Check if the current environment satisfies the requirements
     let site_packages = SitePackages::from_environment(&venv)?;
     if spec.source_trees.is_empty() && reinstall.is_none() {

crates/uv/src/commands/project/run.rs

@@ -6,16 +6,17 @@ use anyhow::{Context, Result};
 use tokio::process::Command;
 use tracing::debug;
 
+use pypi_types::Requirement;
 use uv_cache::Cache;
 use uv_cli::ExternalCommand;
 use uv_client::{BaseClientBuilder, Connectivity};
 use uv_configuration::{Concurrency, ExtrasSpecification, PreviewMode};
 use uv_distribution::{VirtualProject, Workspace, WorkspaceError};
 use uv_normalize::PackageName;
-use uv_requirements::RequirementsSource;
+use uv_requirements::{RequirementsSource, RequirementsSpecification};
 use uv_toolchain::{
-    EnvironmentPreference, Interpreter, PythonEnvironment, Toolchain, ToolchainPreference,
-    ToolchainRequest,
+    request_from_version_file, EnvironmentPreference, Interpreter, PythonEnvironment, Toolchain,
+    ToolchainPreference, ToolchainRequest, VersionRequest,
 };
 use uv_warnings::warn_user_once;
 
@@ -49,8 +50,83 @@ pub(crate) async fn run(
     // Parse the input command.
     let command = RunCommand::from(command);
 
+    // Determine whether the command to execute is a PEP 723 script.
+    let temp_dir;
+    let script_interpreter = if let RunCommand::Python(target, _) = &command {
+        if let Some(metadata) = uv_scripts::read_pep723_metadata(&target).await? {
+            debug!("Found PEP 723 script at: {}", target.display());
+
+            let spec = RequirementsSpecification::from_requirements(
+                metadata
+                    .dependencies
+                    .into_iter()
+                    .map(Requirement::from)
+                    .collect(),
+            );
+
+            // (1) Explicit request from user
+            let python_request = if let Some(request) = python.as_deref() {
+                Some(ToolchainRequest::parse(request))
+                // (2) Request from `.python-version`
+            } else if let Some(request) = request_from_version_file().await? {
+                Some(request)
+                // (3) `Requires-Python` in `pyproject.toml`
+            } else {
+                metadata.requires_python.map(|requires_python| {
+                    ToolchainRequest::Version(VersionRequest::Range(requires_python))
+                })
+            };
+
+            let client_builder = BaseClientBuilder::new()
+                .connectivity(connectivity)
+                .native_tls(native_tls);
+
+            let interpreter = Toolchain::find_or_fetch(
+                python_request,
+                EnvironmentPreference::Any,
+                toolchain_preference,
+                client_builder,
+                cache,
+            )
+            .await?
+            .into_interpreter();
+
+            // Create a virtual environment
+            temp_dir = cache.environment()?;
+            let venv = uv_virtualenv::create_venv(
+                temp_dir.path(),
+                interpreter,
+                uv_virtualenv::Prompt::None,
+                false,
+                false,
+            )?;
+
+            // Install the script requirements.
+            let environment = project::update_environment(
+                venv,
+                spec,
+                &settings,
+                preview,
+                connectivity,
+                concurrency,
+                native_tls,
+                cache,
+                printer,
+            )
+            .await?;
+
+            Some(environment.into_interpreter())
+        } else {
+            None
+        }
+    } else {
+        None
+    };
+
     // Discover and sync the base environment.
-    let base_interpreter = if isolated {
+    let base_interpreter = if let Some(script_interpreter) = script_interpreter {
+        Some(script_interpreter)
+    } else if isolated {
         // package is `None`, isolated and package are marked as conflicting in clap.
         None
     } else {
@@ -199,11 +275,18 @@ pub(crate) async fn run(
             false,
         )?;
 
+        let client_builder = BaseClientBuilder::new()
+            .connectivity(connectivity)
+            .native_tls(native_tls);
+
+        let spec =
+            RequirementsSpecification::from_simple_sources(&requirements, &client_builder).await?;
+
         // Install the ephemeral requirements.
         Some(
             project::update_environment(
                 venv,
-                &requirements,
+                spec,
                 &settings,
                 preview,
                 connectivity,
@@ -316,8 +399,8 @@ impl std::fmt::Display for RunCommand {
                 }
                 Ok(())
             }
-            Self::External(command, args) => {
-                write!(f, "{}", command.to_string_lossy())?;
+            Self::External(executable, args) => {
+                write!(f, "{}", executable.to_string_lossy())?;
                 for arg in args {
                     write!(f, " {}", arg.to_string_lossy())?;
                 }

crates/uv/src/commands/tool/install.rs

@@ -7,7 +7,6 @@ use anyhow::{bail, Context, Result};
 use distribution_types::Name;
 use itertools::Itertools;
 
-use pep508_rs::Requirement;
 use pypi_types::VerbatimParsedUrl;
 use tracing::debug;
 use uv_cache::Cache;
@@ -17,7 +16,7 @@ use uv_configuration::{Concurrency, PreviewMode, Reinstall};
 use uv_fs::replace_symlink;
 use uv_fs::Simplified;
 use uv_installer::SitePackages;
-use uv_requirements::RequirementsSource;
+use uv_requirements::RequirementsSpecification;
 use uv_tool::{entrypoint_paths, find_executable_directory, InstalledTools, Tool, ToolEntrypoint};
 use uv_toolchain::{EnvironmentPreference, Toolchain, ToolchainPreference, ToolchainRequest};
 use uv_warnings::warn_user_once;
@@ -48,11 +47,12 @@ pub(crate) async fn install(
     }
 
     let from = if let Some(from) = from {
-        let from_requirement = Requirement::<VerbatimParsedUrl>::from_str(&from)?;
+        let from_requirement = pep508_rs::Requirement::<VerbatimParsedUrl>::from_str(&from)?;
         // Check if the user provided more than just a name positionally or if that name conflicts with `--from`
         if from_requirement.name.to_string() != package {
             // Determine if its an entirely different package or a conflicting specification
-            let package_requirement = Requirement::<VerbatimParsedUrl>::from_str(&package)?;
+            let package_requirement =
+                pep508_rs::Requirement::<VerbatimParsedUrl>::from_str(&package)?;
             if from_requirement.name == package_requirement.name {
                 bail!(
                     "Package requirement `{}` provided with `--from` conflicts with install request `{}`",
@@ -68,7 +68,7 @@ pub(crate) async fn install(
         }
         from_requirement
     } else {
-        Requirement::<VerbatimParsedUrl>::from_str(&package)?
+        pep508_rs::Requirement::<VerbatimParsedUrl>::from_str(&package)?
     };
 
     let name = from.name.to_string();
@@ -102,14 +102,19 @@ pub(crate) async fn install(
 
     let requirements = [Ok(from.clone())]
         .into_iter()
-        .chain(with.iter().map(|name| Requirement::from_str(name)))
-        .collect::<Result<Vec<Requirement<VerbatimParsedUrl>>, _>>()?;
+        .chain(
+            with.iter()
+                .map(|name| pep508_rs::Requirement::from_str(name)),
+        )
+        .collect::<Result<Vec<pep508_rs::Requirement<VerbatimParsedUrl>>, _>>()?;
 
-    // TODO(zanieb): Duplicative with the above parsing but needed for `update_environment`
-    let requirements_sources = [RequirementsSource::from_package(from.to_string())]
-        .into_iter()
-        .chain(with.into_iter().map(RequirementsSource::from_package))
-        .collect::<Vec<_>>();
+    let spec = RequirementsSpecification::from_requirements(
+        requirements
+            .iter()
+            .cloned()
+            .map(pypi_types::Requirement::from)
+            .collect(),
+    );
 
     let Some(from) = requirements.first().cloned() else {
         bail!("Expected at least one requirement")
@@ -139,7 +144,7 @@ pub(crate) async fn install(
     // Install the ephemeral requirements.
     let environment = update_environment(
         environment,
-        &requirements_sources,
+        spec,
         &settings,
         preview,
         connectivity,

crates/uv/src/commands/tool/run.rs

@@ -11,9 +11,9 @@ use tracing::debug;
 
 use uv_cache::Cache;
 use uv_cli::ExternalCommand;
-use uv_client::Connectivity;
+use uv_client::{BaseClientBuilder, Connectivity};
 use uv_configuration::{Concurrency, PreviewMode};
-use uv_requirements::RequirementsSource;
+use uv_requirements::{RequirementsSource, RequirementsSpecification};
 use uv_toolchain::{
     EnvironmentPreference, PythonEnvironment, Toolchain, ToolchainPreference, ToolchainRequest,
 };
@@ -60,6 +60,13 @@ pub(crate) async fn run(
         .chain(with.into_iter().map(RequirementsSource::from_package))
         .collect::<Vec<_>>();
 
+    let client_builder = BaseClientBuilder::new()
+        .connectivity(connectivity)
+        .native_tls(native_tls);
+
+    let spec =
+        RequirementsSpecification::from_simple_sources(&requirements, &client_builder).await?;
+
     // TODO(zanieb): When implementing project-level tools, discover the project and check if it has the tool.
     // TODO(zanieb): Determine if we should layer on top of the project environment if it is present.
 
@@ -93,7 +100,7 @@ pub(crate) async fn run(
     let ephemeral_env = Some(
         update_environment(
             venv,
-            &requirements,
+            spec,
             &settings,
             preview,
             connectivity,

crates/uv/tests/run.rs

@@ -171,3 +171,95 @@ fn run_args() -> Result<()> {
 
     Ok(())
 }
+
+/// Run a PEP 723-compatible script. The script should take precedence over the workspace
+/// dependencies.
+#[test]
+fn run_script() -> Result<()> {
+    let context = TestContext::new("3.12");
+
+    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    pyproject_toml.write_str(indoc! { r#"
+        [project]
+        name = "foo"
+        version = "1.0.0"
+        requires-python = ">=3.8"
+        dependencies = ["anyio"]
+        "#
+    })?;
+
+    // If the script contains a PEP 723 tag, we should install its requirements.
+    let test_script = context.temp_dir.child("main.py");
+    test_script.write_str(indoc! { r#"
+        # /// script
+        # requires-python = ">=3.11"
+        # dependencies = [
+        #   "iniconfig",
+        # ]
+        # ///
+
+        import iniconfig
+       "#
+    })?;
+
+    uv_snapshot!(context.filters(), context.run().arg("--preview").arg("main.py"), @r###"
+        success: true
+        exit_code: 0
+        ----- stdout -----
+
+        ----- stderr -----
+        Resolved 1 package in [TIME]
+        Prepared 1 package in [TIME]
+        Installed 1 package in [TIME]
+         + iniconfig==2.0.0
+        "###);
+
+    // Otherwise, the script requirements should _not_ be available, but the project requirements
+    // should.
+    let test_non_script = context.temp_dir.child("main.py");
+    test_non_script.write_str(indoc! { r"
+        import iniconfig
+       "
+    })?;
+
+    uv_snapshot!(context.filters(), context.run().arg("--preview").arg("main.py"), @r###"
+    success: false
+    exit_code: 1
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 6 packages in [TIME]
+    Prepared 4 packages in [TIME]
+    Installed 4 packages in [TIME]
+     + anyio==4.3.0
+     + foo==1.0.0 (from file://[TEMP_DIR]/)
+     + idna==3.6
+     + sniffio==1.3.1
+    Traceback (most recent call last):
+      File "[TEMP_DIR]/main.py", line 1, in <module>
+        import iniconfig
+    ModuleNotFoundError: No module named 'iniconfig'
+    "###);
+
+    // But the script should be runnable.
+    let test_non_script = context.temp_dir.child("main.py");
+    test_non_script.write_str(indoc! { r#"
+        import idna
+
+        print("Hello, world!")
+       "#
+    })?;
+
+    uv_snapshot!(context.filters(), context.run().arg("--preview").arg("main.py"), @r###"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+    Hello, world!
+
+    ----- stderr -----
+    Resolved 6 packages in [TIME]
+    Audited 4 packages in [TIME]
+    "###);
+
+    Ok(())
+}