Fix uv sync --no-sources not switching from editable to registry installations

crates/uv-dispatch/src/lib.rs

@@ -28,7 +28,7 @@ use uv_distribution_types::{
     PackageConfigSettings, Requirement, Resolution, SourceDist, VersionOrUrlRef,
 };
 use uv_git::GitResolver;
-use uv_installer::{Installer, Plan, Planner, Preparer, SitePackages};
+use uv_installer::{InstallationStrategy, Installer, Plan, Planner, Preparer, SitePackages};
 use uv_preview::Preview;
 use uv_pypi_types::Conflicts;
 use uv_python::{Interpreter, PythonEnvironment};
@@ -316,6 +316,7 @@ impl BuildContext for BuildDispatch<'_> {
             extraneous: _,
         } = Planner::new(resolution).build(
             site_packages,
+            InstallationStrategy::Permissive,
             &Reinstall::default(),
             self.build_options,
             self.hasher,

crates/uv-installer/src/lib.rs

@@ -2,7 +2,9 @@ pub use compile::{CompileError, compile_tree};
 pub use installer::{Installer, Reporter as InstallReporter};
 pub use plan::{Plan, Planner};
 pub use preparer::{Error as PrepareError, Preparer, Reporter as PrepareReporter};
-pub use site_packages::{SatisfiesResult, SitePackages, SitePackagesDiagnostic};
+pub use site_packages::{
+    InstallationStrategy, SatisfiesResult, SitePackages, SitePackagesDiagnostic,
+};
 pub use uninstall::{UninstallError, uninstall};
 
 mod compile;

crates/uv-installer/src/plan.rs

@@ -23,8 +23,8 @@ use uv_pypi_types::VerbatimParsedUrl;
 use uv_python::PythonEnvironment;
 use uv_types::HashStrategy;
 
-use crate::SitePackages;
 use crate::satisfies::RequirementSatisfaction;
+use crate::{InstallationStrategy, SitePackages};
 
 /// A planner to generate an [`Plan`] based on a set of requirements.
 #[derive(Debug)]
@@ -52,6 +52,7 @@ impl<'a> Planner<'a> {
     pub fn build(
         self,
         mut site_packages: SitePackages,
+        installation: InstallationStrategy,
         reinstall: &Reinstall,
         build_options: &BuildOptions,
         hasher: &HashStrategy,
@@ -125,6 +126,7 @@ impl<'a> Planner<'a> {
                             dist.name(),
                             installed,
                             &source,
+                            installation,
                             tags,
                             config_settings,
                             config_settings_package,

crates/uv-installer/src/satisfies.rs

@@ -19,6 +19,8 @@ use uv_normalize::PackageName;
 use uv_platform_tags::{IncompatibleTag, TagCompatibility, Tags};
 use uv_pypi_types::{DirInfo, DirectUrl, VcsInfo, VcsKind};
 
+use crate::InstallationStrategy;
+
 #[derive(Debug, Copy, Clone)]
 pub(crate) enum RequirementSatisfaction {
     Mismatch,
@@ -35,6 +37,7 @@ impl RequirementSatisfaction {
         name: &PackageName,
         distribution: &InstalledDist,
         source: &RequirementSource,
+        installation: InstallationStrategy,
         tags: &Tags,
         config_settings: &ConfigSettings,
         config_settings_package: &PackageConfigSettings,
@@ -67,6 +70,26 @@ impl RequirementSatisfaction {
         match source {
             // If the requirement comes from a registry, check by name.
             RequirementSource::Registry { specifier, .. } => {
+                // If the installed distribution is _not_ from a registry, reject it if and only if
+                // we're in a stateless install.
+                //
+                // For example: the `uv pip` CLI is stateful, in that it "respects"
+                // already-installed packages in the virtual environment. So if you run `uv pip
+                // install ./path/to/idna`, and then `uv pip install anyio` (which depends on
+                // `idna`), we'll "accept" the already-installed `idna` even though it is implicitly
+                // being "required" as a registry package.
+                //
+                // The `uv sync` CLI is stateless, in that all requirements must be defined
+                // declaratively ahead-of-time. So if you `uv sync` to install `./path/to/idna` and
+                // later `uv sync` to install `anyio`, we'll know (during that second sync) if the
+                // already-installed `idna` should come from the registry or not.
+                if installation == InstallationStrategy::Strict {
+                    if !matches!(distribution.kind, InstalledDistKind::Registry { .. }) {
+                        debug!("Distribution type mismatch for {name}: {distribution:?}");
+                        return Self::Mismatch;
+                    }
+                }
+
                 if !specifier.contains(distribution.version()) {
                     return Self::Mismatch;
                 }

crates/uv-installer/src/site_packages.rs

@@ -314,6 +314,7 @@ impl SitePackages {
         requirements: &[UnresolvedRequirementSpecification],
         constraints: &[NameRequirementSpecification],
         overrides: &[UnresolvedRequirementSpecification],
+        installation: InstallationStrategy,
         markers: &ResolverMarkerEnvironment,
         tags: &Tags,
         config_settings: &ConfigSettings,
@@ -404,6 +405,7 @@ impl SitePackages {
             requirements.iter().map(Cow::as_ref),
             constraints.iter().map(|constraint| &constraint.requirement),
             overrides.iter().map(Cow::as_ref),
+            installation,
             markers,
             tags,
             config_settings,
@@ -419,6 +421,7 @@ impl SitePackages {
         requirements: impl ExactSizeIterator<Item = &'a Requirement>,
         constraints: impl Iterator<Item = &'a Requirement>,
         overrides: impl Iterator<Item = &'a Requirement>,
+        installation: InstallationStrategy,
         markers: &ResolverMarkerEnvironment,
         tags: &Tags,
         config_settings: &ConfigSettings,
@@ -482,6 +485,7 @@ impl SitePackages {
                             name,
                             distribution,
                             &requirement.source,
+                            installation,
                             tags,
                             config_settings,
                             config_settings_package,
@@ -504,6 +508,7 @@ impl SitePackages {
                                 name,
                                 distribution,
                                 &constraint.source,
+                                installation,
                                 tags,
                                 config_settings,
                                 config_settings_package,
@@ -560,6 +565,27 @@ impl SitePackages {
     }
 }
 
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum InstallationStrategy {
+    /// A permissive installation strategy, which accepts existing installations even if the source
+    /// type differs, as in the `pip` and `uv pip` CLIs.
+    ///
+    /// In this strategy, packages that are already installed in the environment may be reused if
+    /// they implicitly match the requirements. For example, if the user installs `./path/to/idna`,
+    /// then runs `uv pip install anyio` (which depends on `idna`), the existing `idna` installation
+    /// will be reused if its version matches the requirement, even though it was installed from a
+    /// path and is being implicitly requested from a registry.
+    Permissive,
+
+    /// A strict installation strategy, which requires that existing installations match the source
+    /// type, as in the `uv sync` CLI.
+    ///
+    /// This strategy enforces that the installation source must match the requirement source.
+    /// It prevents reusing packages that were installed from different sources, ensuring
+    /// declarative and reproducible environments.
+    Strict,
+}
+
 /// We check if all requirements are already satisfied, recursing through the requirements tree.
 #[derive(Debug)]
 pub enum SatisfiesResult {

crates/uv-resolver/src/candidate_selector.rs

@@ -6,8 +6,10 @@ use pubgrub::Range;
 use smallvec::SmallVec;
 use tracing::{debug, trace};
 
-use uv_configuration::IndexStrategy;
-use uv_distribution_types::{CompatibleDist, IncompatibleDist, IncompatibleSource, IndexUrl};
+use uv_configuration::{IndexStrategy, SourceStrategy};
+use uv_distribution_types::{
+    CompatibleDist, IncompatibleDist, IncompatibleSource, IndexUrl, InstalledDistKind,
+};
 use uv_distribution_types::{DistributionMetadata, IncompatibleWheel, Name, PrioritizedDist};
 use uv_normalize::PackageName;
 use uv_pep440::Version;
@@ -26,6 +28,7 @@ pub(crate) struct CandidateSelector {
     resolution_strategy: ResolutionStrategy,
     prerelease_strategy: PrereleaseStrategy,
     index_strategy: IndexStrategy,
+    source_strategy: SourceStrategy,
 }
 
 impl CandidateSelector {
@@ -34,6 +37,7 @@ impl CandidateSelector {
         options: &Options,
         manifest: &Manifest,
         env: &ResolverEnvironment,
+        source_strategy: SourceStrategy,
     ) -> Self {
         Self {
             resolution_strategy: ResolutionStrategy::from_mode(
@@ -49,6 +53,7 @@ impl CandidateSelector {
                 options.dependency_mode,
             ),
             index_strategy: options.index_strategy,
+            source_strategy,
         }
     }
 
@@ -119,7 +124,13 @@ impl CandidateSelector {
         let installed = if reinstall {
             None
         } else {
-            Self::get_installed(package_name, range, installed_packages, tags)
+            Self::get_installed(
+                package_name,
+                range,
+                installed_packages,
+                tags,
+                self.source_strategy,
+            )
         };
 
         // If we're not upgrading, we should prefer the already-installed distribution.
@@ -369,6 +380,7 @@ impl CandidateSelector {
         range: &Range<Version>,
         installed_packages: &'a InstalledPackages,
         tags: Option<&'a Tags>,
+        source_strategy: SourceStrategy,
     ) -> Option<Candidate<'a>> {
         let installed_dists = installed_packages.get_packages(package_name);
         match installed_dists.as_slice() {
@@ -381,6 +393,16 @@ impl CandidateSelector {
                     return None;
                 }
 
+                // When sources are disabled, only allow registry installations to be reused
+                if matches!(source_strategy, SourceStrategy::Disabled) {
+                    if !matches!(dist.kind, InstalledDistKind::Registry(_)) {
+                        debug!(
+                            "Source strategy is disabled, rejecting non-registry installed distribution: {dist}"
+                        );
+                        return None;
+                    }
+                }
+
                 // Verify that the installed distribution is compatible with the environment.
                 if tags.is_some_and(|tags| {
                     let Ok(Some(wheel_tags)) = dist.read_tags() else {

crates/uv-resolver/src/resolver/mod.rs

@@ -20,7 +20,7 @@ use tokio::sync::oneshot;
 use tokio_stream::wrappers::ReceiverStream;
 use tracing::{Level, debug, info, instrument, trace, warn};
 
-use uv_configuration::{Constraints, Overrides};
+use uv_configuration::{Constraints, Overrides, SourceStrategy};
 use uv_distribution::{ArchiveMetadata, DistributionDatabase};
 use uv_distribution_types::{
     BuiltDist, CompatibleDist, DerivationChain, Dist, DistErrorKind, DistributionMetadata,
@@ -36,6 +36,7 @@ use uv_pep508::{
 };
 use uv_platform_tags::Tags;
 use uv_pypi_types::{ConflictItem, ConflictItemRef, ConflictKindRef, Conflicts, VerbatimParsedUrl};
+use uv_torch::TorchStrategy;
 use uv_types::{BuildContext, HashStrategy, InstalledPackagesProvider};
 use uv_warnings::warn_user_once;
 
@@ -82,7 +83,6 @@ use crate::{
     marker,
 };
 pub(crate) use provider::MetadataUnavailable;
-use uv_torch::TorchStrategy;
 
 mod availability;
 mod batch_prefetch;
@@ -201,6 +201,7 @@ impl<'a, Context: BuildContext, InstalledPackages: InstalledPackagesProvider>
             build_context.git(),
             build_context.capabilities(),
             build_context.locations(),
+            build_context.sources(),
             provider,
             installed_packages,
         )
@@ -224,14 +225,15 @@ impl<Provider: ResolverProvider, InstalledPackages: InstalledPackagesProvider>
         git: &GitResolver,
         capabilities: &IndexCapabilities,
         locations: &IndexLocations,
+        source_strategy: SourceStrategy,
         provider: Provider,
         installed_packages: InstalledPackages,
     ) -> Result<Self, ResolveError> {
         let state = ResolverState {
             index: index.clone(),
             git: git.clone(),
             capabilities: capabilities.clone(),
-            selector: CandidateSelector::for_resolution(&options, &manifest, &env),
+            selector: CandidateSelector::for_resolution(&options, &manifest, &env, source_strategy),
             dependency_mode: options.dependency_mode,
             urls: Urls::from_manifest(&manifest, &env, git, options.dependency_mode),
             indexes: Indexes::from_manifest(&manifest, &env, options.dependency_mode),

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

@@ -22,7 +22,7 @@ use uv_distribution_types::{
 };
 use uv_fs::Simplified;
 use uv_install_wheel::LinkMode;
-use uv_installer::{SatisfiesResult, SitePackages};
+use uv_installer::{InstallationStrategy, SatisfiesResult, SitePackages};
 use uv_normalize::{DefaultExtras, DefaultGroups};
 use uv_preview::{Preview, PreviewFeatures};
 use uv_pypi_types::Conflicts;
@@ -289,6 +289,7 @@ pub(crate) async fn pip_install(
             &requirements,
             &constraints,
             &overrides,
+            InstallationStrategy::Permissive,
             &marker_env,
             &tags,
             config_settings,
@@ -602,6 +603,7 @@ pub(crate) async fn pip_install(
     match operations::install(
         &resolution,
         site_packages,
+        InstallationStrategy::Permissive,
         modifications,
         &reinstall,
         &build_options,

crates/uv/src/commands/pip/operations.rs

@@ -25,7 +25,7 @@ use uv_distribution_types::{
 use uv_distribution_types::{DistributionMetadata, InstalledMetadata, Name, Resolution};
 use uv_fs::Simplified;
 use uv_install_wheel::LinkMode;
-use uv_installer::{Plan, Planner, Preparer, SitePackages};
+use uv_installer::{InstallationStrategy, Plan, Planner, Preparer, SitePackages};
 use uv_normalize::PackageName;
 use uv_pep508::{MarkerEnvironment, RequirementOrigin};
 use uv_platform_tags::Tags;
@@ -436,6 +436,7 @@ impl Changelog {
 pub(crate) async fn install(
     resolution: &Resolution,
     site_packages: SitePackages,
+    installation: InstallationStrategy,
     modifications: Modifications,
     reinstall: &Reinstall,
     build_options: &BuildOptions,
@@ -462,6 +463,7 @@ pub(crate) async fn install(
     let plan = Planner::new(resolution)
         .build(
             site_packages,
+            installation,
             reinstall,
             build_options,
             hasher,

crates/uv/src/commands/pip/sync.rs

@@ -20,7 +20,7 @@ use uv_distribution_types::{
 };
 use uv_fs::Simplified;
 use uv_install_wheel::LinkMode;
-use uv_installer::SitePackages;
+use uv_installer::{InstallationStrategy, SitePackages};
 use uv_normalize::{DefaultExtras, DefaultGroups};
 use uv_preview::{Preview, PreviewFeatures};
 use uv_pypi_types::Conflicts;
@@ -533,6 +533,7 @@ pub(crate) async fn pip_sync(
     match operations::install(
         &resolution,
         site_packages,
+        InstallationStrategy::Permissive,
         Modifications::Exact,
         &reinstall,
         &build_options,

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

@@ -23,7 +23,7 @@ use uv_distribution_types::{
 };
 use uv_fs::{CWD, LockedFile, Simplified};
 use uv_git::ResolvedRepositoryReference;
-use uv_installer::{SatisfiesResult, SitePackages};
+use uv_installer::{InstallationStrategy, SatisfiesResult, SitePackages};
 use uv_normalize::{DEV_DEPENDENCIES, DefaultGroups, ExtraName, GroupName, PackageName};
 use uv_pep440::{TildeVersionSpecifier, Version, VersionSpecifiers};
 use uv_pep508::MarkerTreeContents;
@@ -2124,6 +2124,7 @@ pub(crate) async fn sync_environment(
     pip::operations::install(
         resolution,
         site_packages,
+        InstallationStrategy::Permissive,
         modifications,
         reinstall,
         build_options,
@@ -2243,6 +2244,7 @@ pub(crate) async fn update_environment(
             &requirements,
             &constraints,
             &overrides,
+            InstallationStrategy::Permissive,
             &marker_env,
             &tags,
             config_setting,
@@ -2388,6 +2390,7 @@ pub(crate) async fn update_environment(
     let changelog = pip::operations::install(
         &resolution,
         site_packages,
+        InstallationStrategy::Permissive,
         modifications,
         reinstall,
         build_options,