Allow workspace root sources to override member non-workspace sources for workspace members

When a workspace member (e.g., `app-a`) declares a non-workspace source (Git, path, etc.)
for another workspace member (e.g., `lib-x`) in its `tool.uv.sources`, but the workspace
root declares `lib-x = { workspace = true }`, fall back to the workspace root's source
instead of raising a `NonWorkspaceSource` error.

This supports the pattern where members declare Git sources for standalone use outside
the workspace, while the workspace root overrides them as workspace sources when
developing within the monorepo.

The regression was introduced in v0.9.3 when commit b151e0e fixed workspace member
glob normalization for `./` prefixed paths. Before that fix, workspaces using
`members = ["./packages/..."]` didn't properly discover members from child directories,
so the workspace member source check didn't fire.

Fixes #18232

https://claude.ai/code/session_01XBDgKsN3dyqoucYic8YNGn

Author: claude

crates/uv-distribution/src/metadata/lowering.rs

@@ -56,6 +56,34 @@ impl LoweredRequirement {
             (None, RequirementOrigin::Project)
         };
 
+        // If the project declares a non-workspace source for a workspace member (e.g., a Git
+        // source for standalone use), but the workspace root declares it as a workspace source,
+        // prefer the workspace root's source.
+        let (sources, origin) = if matches!(origin, RequirementOrigin::Project)
+            && workspace.packages().contains_key(&requirement.name)
+            && sources.is_some_and(|s| s.iter().any(|s| !matches!(s, Source::Workspace { .. })))
+        {
+            if let Some(workspace_source) = workspace.sources().get(&requirement.name) {
+                if workspace_source.iter().any(|s| {
+                    matches!(
+                        s,
+                        Source::Workspace {
+                            workspace: true,
+                            ..
+                        }
+                    )
+                }) {
+                    (Some(workspace_source), RequirementOrigin::Workspace)
+                } else {
+                    (sources, origin)
+                }
+            } else {
+                (sources, origin)
+            }
+        } else {
+            (sources, origin)
+        };
+
         // If the source only applies to a given extra or dependency group, filter it out.
         let sources = sources.map(|sources| {
             sources

crates/uv/tests/it/lock.rs

@@ -9726,6 +9726,86 @@ fn lock_no_workspace_source() -> Result<()> {
     Ok(())
 }
 
+/// When a workspace member declares a non-workspace source (e.g., Git, path) for another workspace
+/// member, but the workspace root declares `workspace = true` for that same member, the workspace
+/// root's source should take precedence. This supports the pattern where members declare
+/// non-workspace sources (e.g., Git, path) for standalone use, while the workspace root overrides
+/// them as workspace sources.
+///
+/// See: <https://github.com/astral-sh/uv/issues/18232>
+#[test]
+fn lock_member_non_workspace_source_with_root_workspace_source() -> Result<()> {
+    let context = uv_test::test_context!("3.12");
+
+    let root_pyproject = context.temp_dir.child("pyproject.toml");
+    root_pyproject.write_str(
+        r#"
+        [project]
+        name = "monorepo"
+        version = "1.0.0"
+        requires-python = ">=3.12"
+        dependencies = ["app-a", "lib-x"]
+
+        [tool.uv.sources]
+        app-a = { workspace = true }
+        lib-x = { workspace = true }
+
+        [tool.uv.workspace]
+        members = ["packages/app-a", "packages/lib-x"]
+        "#,
+    )?;
+
+    let app_a = context.temp_dir.child("packages").child("app-a");
+    fs_err::create_dir_all(&app_a)?;
+
+    let app_a_pyproject = app_a.child("pyproject.toml");
+    app_a_pyproject.write_str(
+        r#"
+        [project]
+        name = "app-a"
+        version = "0.1.0"
+        requires-python = ">=3.12"
+        dependencies = ["lib-x"]
+
+        [tool.uv.sources]
+        lib-x = { path = "../../packages/lib-x", editable = false }
+
+        [build-system]
+        requires = ["uv_build>=0.7,<10000"]
+        build-backend = "uv_build"
+        "#,
+    )?;
+
+    let lib_x = context.temp_dir.child("packages").child("lib-x");
+    fs_err::create_dir_all(&lib_x)?;
+
+    let lib_x_pyproject = lib_x.child("pyproject.toml");
+    lib_x_pyproject.write_str(
+        r#"
+        [project]
+        name = "lib-x"
+        version = "1.0.0"
+        requires-python = ">=3.12"
+        dependencies = []
+
+        [build-system]
+        requires = ["uv_build>=0.7,<10000"]
+        build-backend = "uv_build"
+        "#,
+    )?;
+
+    uv_snapshot!(context.filters(), context.lock(), @r"
+    success: true
+    exit_code: 0
+    ----- stdout -----
+
+    ----- stderr -----
+    Resolved 3 packages in [TIME]
+    ");
+
+    Ok(())
+}
+
 /// Lock a workspace with a member that's a peer to the root.
 #[test]
 fn lock_peer_member() -> Result<()> {