Sync index format when uv add --index updates an existing index URL

crates/uv-workspace/src/pyproject_mut.rs

@@ -11,12 +11,11 @@ use toml_edit::{
 };
 
 use uv_cache_key::CanonicalUrl;
-use uv_distribution_types::Index;
-use uv_fs::PortablePath;
+use uv_distribution_types::{Index, IndexFormat, IndexUrl};
+use uv_fs::{PortablePath, is_same_file_allow_missing};
 use uv_normalize::{ExtraName, GroupName, PackageName};
 use uv_pep440::{Version, VersionParseError, VersionSpecifier, VersionSpecifiers};
 use uv_pep508::{MarkerTree, Requirement, VersionOrUrl};
-use uv_redacted::DisplaySafeUrl;
 
 use crate::pyproject::{DependencyType, Source};
 
@@ -29,6 +28,21 @@ pub struct PyProjectTomlMut {
     target: DependencyTarget,
 }
 
+fn index_locations_equal(existing: &str, incoming: &IndexUrl, root_dir: &Path) -> bool {
+    let Ok(existing) = IndexUrl::parse(existing, Some(root_dir)) else {
+        return false;
+    };
+
+    if let (IndexUrl::Path(existing), IndexUrl::Path(incoming)) = (&existing, incoming)
+        && let (Ok(existing), Ok(incoming)) = (existing.to_file_path(), incoming.to_file_path())
+        && let Some(equal) = is_same_file_allow_missing(&existing, &incoming)
+    {
+        return equal;
+    }
+
+    CanonicalUrl::new(existing.url()) == CanonicalUrl::new(incoming.url())
+}
+
 #[derive(Error, Debug)]
 pub enum Error {
     #[error("Failed to parse `pyproject.toml`")]
@@ -428,7 +442,7 @@ impl PyProjectTomlMut {
     }
 
     /// Add an [`Index`] to `tool.uv.index`.
-    pub fn add_index(&mut self, index: &Index) -> Result<(), Error> {
+    pub fn add_index(&mut self, index: &Index, root_dir: &Path) -> Result<(), Error> {
         let size = self.doc.len();
         let existing = self
             .doc
@@ -472,10 +486,7 @@ impl PyProjectTomlMut {
                 if table
                     .get("url")
                     .and_then(|item| item.as_str())
-                    .and_then(|url| DisplaySafeUrl::parse(url).ok())
-                    .is_some_and(|url| {
-                        CanonicalUrl::new(&url) == CanonicalUrl::new(index.url.url())
-                    })
+                    .is_some_and(|url| index_locations_equal(url, &index.url, root_dir))
                 {
                     return true;
                 }
@@ -504,12 +515,16 @@ impl PyProjectTomlMut {
             table.insert("name", Value::String(formatted).into());
         }
 
+        let existing_url = table.get("url").and_then(|item| item.as_str());
+
+        // Update the stored URL independently of whether the index location changed.
+        let url_needs_update =
+            existing_url.is_none_or(|url| url != index.url.without_credentials().as_str());
+        let index_location_changed =
+            existing_url.is_none_or(|url| !index_locations_equal(url, &index.url, root_dir));
+
         // If necessary, update the URL.
-        if table
-            .get("url")
-            .and_then(|item| item.as_str())
-            .is_none_or(|url| url != index.url.without_credentials().as_str())
-        {
+        if url_needs_update {
             let mut formatted = Formatted::new(index.url.without_credentials().to_string());
             if let Some(value) = table.get("url").and_then(Item::as_value) {
                 if let Some(prefix) = value.decor().prefix() {
@@ -542,6 +557,34 @@ impl PyProjectTomlMut {
             }
         }
 
+        // If the index location changed, sync the format to match the incoming index.
+        if index_location_changed {
+            match index.format {
+                IndexFormat::Flat => {
+                    if table
+                        .get("format")
+                        .and_then(Item::as_str)
+                        .is_none_or(|format| format != "flat")
+                    {
+                        let mut formatted = Formatted::new("flat".to_string());
+                        if let Some(value) = table.get("format").and_then(Item::as_value) {
+                            if let Some(prefix) = value.decor().prefix() {
+                                formatted.decor_mut().set_prefix(prefix.clone());
+                            }
+                            if let Some(suffix) = value.decor().suffix() {
+                                formatted.decor_mut().set_suffix(suffix.clone());
+                            }
+                        }
+                        table.insert("format", Value::String(formatted).into());
+                    }
+                }
+                IndexFormat::Simple => {
+                    // Remove the format key if it exists (Simple is the default).
+                    table.remove("format");
+                }
+            }
+        }
+
         // Remove any replaced tables.
         existing.retain(|table| {
             // If the index has the same name, skip it.
@@ -567,8 +610,7 @@ impl PyProjectTomlMut {
             if table
                 .get("url")
                 .and_then(|item| item.as_str())
-                .and_then(|url| DisplaySafeUrl::parse(url).ok())
-                .is_some_and(|url| CanonicalUrl::new(&url) == CanonicalUrl::new(index.url.url()))
+                .is_some_and(|url| index_locations_equal(url, &index.url, root_dir))
             {
                 return false;
             }
@@ -1829,8 +1871,10 @@ mod test {
     };
     use anyhow::Result;
     use insta::assert_snapshot;
+    use std::path::Path;
     use std::str::FromStr;
     use toml_edit::DocumentMut;
+    use uv_distribution_types::Index;
     use uv_normalize::PackageName;
     use uv_pep440::Version;
     use uv_pep508::Requirement;
@@ -2283,4 +2327,70 @@ dependencies = [
 "#
         );
     }
+
+    #[test]
+    fn add_index_syncs_format_on_url_update() {
+        let toml = r#"
+[[tool.uv.index]]
+name = "index"
+url = "https://example.com/flat/"
+format = "flat"
+"#;
+
+        let mut doc = PyProjectTomlMut::from_toml(toml, DependencyTarget::PyProjectToml).unwrap();
+
+        // The URL spelling changes, but the canonical URL does not, so format should be preserved.
+        let equivalent_index = Index::from_str("index=https://example.com/flat").unwrap();
+        doc.add_index(&equivalent_index, Path::new(".")).unwrap();
+
+        assert_snapshot!(doc.to_string(), @r#"
+
+[[tool.uv.index]]
+name = "index"
+url = "https://example.com/flat"
+format = "flat"
+"#);
+
+        let new_index = Index::from_str("index=https://pypi.org/simple").unwrap();
+        doc.add_index(&new_index, Path::new(".")).unwrap();
+
+        assert_snapshot!(doc.to_string(), @r#"
+
+[[tool.uv.index]]
+name = "index"
+url = "https://pypi.org/simple"
+"#);
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn add_index_preserves_format_when_windows_path_unchanged() -> Result<()> {
+        let toml = r#"
+[[tool.uv.index]]
+name = "index"
+url = 'C:\links'
+format = "flat"
+"#;
+
+        let mut doc = PyProjectTomlMut::from_toml(toml, DependencyTarget::PyProjectToml)?;
+
+        let new_index = Index::from_str(r"index=C:\links")?;
+        doc.add_index(&new_index, &std::env::current_dir()?)?;
+
+        let expected_url = new_index.url.without_credentials();
+        let index = doc.doc["tool"]["uv"]["index"]
+            .as_array_of_tables()
+            .and_then(|indexes| indexes.get(0))
+            .expect("index table");
+        assert_eq!(
+            index.get("url").and_then(|item| item.as_str()),
+            Some(expected_url.as_str())
+        );
+        assert_eq!(
+            index.get("format").and_then(|item| item.as_str()),
+            Some("flat")
+        );
+
+        Ok(())
+    }
 }

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

@@ -26,7 +26,7 @@ use uv_distribution_types::{
     Identifier, Index, IndexLocations, IndexName, IndexUrl, NameRequirementSpecification,
     Requirement, RequirementSource, UnresolvedRequirement,
 };
-use uv_fs::{LockedFile, LockedFileError, Simplified};
+use uv_fs::{CWD, LockedFile, LockedFileError, Simplified};
 use uv_git::store_credentials;
 use uv_normalize::{DEV_DEPENDENCIES, DefaultExtras, DefaultGroups, ExtraName, PackageName};
 use uv_pep508::{MarkerTree, VersionOrUrl};
@@ -688,11 +688,15 @@ pub(crate) async fn add(
 
     // Add any indexes that were provided on the command-line, in priority order.
     if !raw {
+        let root_dir = match &target {
+            AddTarget::Script(_, _) => CWD.as_path(),
+            AddTarget::Project(project, _) => project.root(),
+        };
         let locations = IndexLocations::new(indexes, Vec::new(), false);
         let mut indexes = locations.defined_indexes().collect::<Vec<_>>();
         indexes.reverse();
         for index in indexes {
-            toml.add_index(index)?;
+            toml.add_index(index, root_dir)?;
         }
     }
 

crates/uv/tests/project/edit.rs

@@ -11255,37 +11255,123 @@ fn add_index_without_trailing_slash() -> Result<()> {
 fn add_index_with_existing_relative_path_index() -> Result<()> {
     let context = uv_test::test_context!("3.12");
 
-    let pyproject_toml = context.temp_dir.child("pyproject.toml");
+    let project = context.temp_dir.child("project");
+    project.create_dir_all()?;
+    let pyproject_toml = project.child("pyproject.toml");
     pyproject_toml.write_str(indoc! {r#"
         [project]
         name = "project"
         version = "0.1.0"
         requires-python = ">=3.12"
         dependencies = []
+
+        [[tool.uv.index]]
+        name = "local"
+        url = "./links-alias"
+        format = "flat"
     "#})?;
 
-    // Create test-index/ subdirectory and copy our "offline" tqdm wheel there
-    let packages = context.temp_dir.child("test-index");
+    // Create a non-empty flat index.
+    let packages = project.child("test-index");
     packages.create_dir_all()?;
+    packages.child("placeholder").touch()?;
+    uv_fs::create_symlink(packages.path(), project.child("links-alias").path())?;
+
+    let index = format!("local={}", packages.path().display());
+    uv_snapshot!(context.filters(), context.add().arg("iniconfig").arg("--frozen").arg("--project").arg(project.path()).arg("--index").arg(index), @"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Using CPython 3.12.[X] interpreter at: [PYTHON-3.12]
+    ");
+
+    let pyproject_toml = fs_err::read_to_string(project.join("pyproject.toml"))?;
+
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(pyproject_toml, @r#"
+        [project]
+        name = "project"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = [
+            "iniconfig",
+        ]
+
+        [[tool.uv.index]]
+        name = "local"
+        url = "file://[TEMP_DIR]/project/test-index"
+        format = "flat"
+
+        [tool.uv.sources]
+        iniconfig = { index = "local" }
+        "#);
+    });
+
+    Ok(())
+}
+
+/// Add an index with an existing relative path to a script outside the working directory.
+#[test]
+fn add_index_with_existing_relative_path_in_script() -> Result<()> {
+    let context = uv_test::test_context!("3.12");
+
+    let scripts = context.temp_dir.child("scripts");
+    scripts.create_dir_all()?;
+    let script = scripts.child("main.py");
+    script.write_str(indoc! {r#"
+        # /// script
+        # requires-python = ">=3.12"
+        # dependencies = []
+        #
+        # [[tool.uv.index]]
+        # name = "local"
+        # url = "./links"
+        # format = "flat"
+        # ///
+    "#})?;
 
+    let packages = context.temp_dir.child("links");
+    packages.create_dir_all()?;
     let wheel_src = context
         .workspace_root
         .join("test/links/ok-1.0.0-py3-none-any.whl");
-    let wheel_dst = packages.child("ok-1.0.0-py3-none-any.whl");
-    fs_err::copy(&wheel_src, &wheel_dst)?;
+    fs_err::copy(&wheel_src, packages.child("ok-1.0.0-py3-none-any.whl"))?;
 
-    uv_snapshot!(context.filters(), context.add().arg("iniconfig").arg("--index").arg("./test-index"), @"
+    uv_snapshot!(context.filters(), context.add().arg("iniconfig").arg("--frozen").arg("--script").arg(script.path()).arg("--index").arg("local=./links"), @"
     success: true
     exit_code: 0
     ----- stdout -----
 
     ----- stderr -----
-    Resolved 2 packages in [TIME]
-    Prepared 1 package in [TIME]
-    Installed 1 package in [TIME]
-     + iniconfig==2.0.0
+    warning: `--frozen` is a no-op for Python scripts with inline metadata, which always run in isolation
     ");
 
+    let script = fs_err::read_to_string(script.path())?;
+    insta::with_settings!({
+        filters => context.filters(),
+    }, {
+        assert_snapshot!(script, @r#"
+        # /// script
+        # requires-python = ">=3.12"
+        # dependencies = [
+        #     "iniconfig",
+        # ]
+        #
+        # [[tool.uv.index]]
+        # name = "local"
+        # url = "file://[TEMP_DIR]/links"
+        # format = "flat"
+        #
+        # [tool.uv.sources]
+        # iniconfig = { index = "local" }
+        # ///
+        "#);
+    });
+
     Ok(())
 }