Improve resolver error messages when --offline is used

crates/uv-resolver/src/pubgrub/report.rs

@@ -827,7 +827,7 @@ impl std::fmt::Display for PubGrubHint {
             Self::Offline => {
                 write!(
                     f,
-                    "{}{} Packages were unavailable because the network was disabled",
+                    "{}{} Packages were unavailable because the network was disabled. When the network is disabled, registry packages may only be read from the cache.",
                     "hint".bold().cyan(),
                     ":".bold(),
                 )

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

@@ -52,9 +52,7 @@ impl Display for UnavailableVersion {
             UnavailableVersion::InvalidMetadata => f.write_str("has invalid metadata"),
             UnavailableVersion::InconsistentMetadata => f.write_str("has inconsistent metadata"),
             UnavailableVersion::InvalidStructure => f.write_str("has an invalid package format"),
-            UnavailableVersion::Offline => f.write_str(
-                "network connectivity is disabled, but the metadata wasn't found in the cache",
-            ),
+            UnavailableVersion::Offline => f.write_str("needs to be downloaded from a registry"),
         }
     }
 }

crates/uv/tests/cache_prune.rs

@@ -248,12 +248,12 @@ fn prune_unzipped() -> Result<()> {
               iniconfig==1.1.0
               iniconfig==1.1.1
               iniconfig==2.0.0
-          network connectivity is disabled, but the metadata wasn't found in the cache, we can conclude that iniconfig<1.0.0 cannot be used.
+          needs to be downloaded from a registry, we can conclude that iniconfig<1.0.0 cannot be used.
           And because you require iniconfig, we can conclude that your requirements are unsatisfiable.
 
           hint: Pre-releases are available for iniconfig in the requested range (e.g., 0.2.dev0), but pre-releases weren't enabled (try: `--prerelease=allow`)
 
-          hint: Packages were unavailable because the network was disabled
+          hint: Packages were unavailable because the network was disabled. When the network is disabled, registry packages may only be read from the cache.
     "###);
 
     Ok(())

crates/uv/tests/lock.rs

@@ -8602,7 +8602,7 @@ fn lock_add_member() -> Result<()> {
       ╰─▶ Because anyio was not found in the cache and leaf depends on anyio>3, we can conclude that leaf's requirements are unsatisfiable.
           And because your workspace requires leaf, we can conclude that your workspace's requirements are unsatisfiable.
 
-          hint: Packages were unavailable because the network was disabled
+          hint: Packages were unavailable because the network was disabled. When the network is disabled, registry packages may only be read from the cache.
     "###);
 
     // Re-run without `--locked`.

crates/uv/tests/pip_compile.rs

@@ -5513,7 +5513,7 @@ fn offline_registry() -> Result<()> {
       × No solution found when resolving dependencies:
       ╰─▶ Because black was not found in the cache and you require black==23.10.1, we can conclude that your requirements are unsatisfiable.
 
-          hint: Packages were unavailable because the network was disabled
+          hint: Packages were unavailable because the network was disabled. When the network is disabled, registry packages may only be read from the cache.
     "###
     );
 
@@ -5644,7 +5644,7 @@ fn offline_find_links() -> Result<()> {
       × No solution found when resolving dependencies:
       ╰─▶ Because tqdm was not found in the cache and you require tqdm, we can conclude that your requirements are unsatisfiable.
 
-          hint: Packages were unavailable because the network was disabled
+          hint: Packages were unavailable because the network was disabled. When the network is disabled, registry packages may only be read from the cache.
     "###
     );
 
@@ -5663,7 +5663,7 @@ fn offline_find_links() -> Result<()> {
       × No solution found when resolving dependencies:
       ╰─▶ Because tqdm was not found in the cache and you require tqdm, we can conclude that your requirements are unsatisfiable.
 
-          hint: Packages were unavailable because the network was disabled
+          hint: Packages were unavailable because the network was disabled. When the network is disabled, registry packages may only be read from the cache.
     "###
     );
 

crates/uv/tests/pip_sync.rs

@@ -2789,7 +2789,7 @@ fn find_links_offline_no_match() -> Result<()> {
       × No solution found when resolving dependencies:
       ╰─▶ Because numpy was not found in the cache and you require numpy, we can conclude that your requirements are unsatisfiable.
 
-          hint: Packages were unavailable because the network was disabled
+          hint: Packages were unavailable because the network was disabled. When the network is disabled, registry packages may only be read from the cache.
     "###
     );
 
@@ -2916,7 +2916,7 @@ fn offline() -> Result<()> {
       × No solution found when resolving dependencies:
       ╰─▶ Because black was not found in the cache and you require black==23.10.1, we can conclude that your requirements are unsatisfiable.
 
-          hint: Packages were unavailable because the network was disabled
+          hint: Packages were unavailable because the network was disabled. When the network is disabled, registry packages may only be read from the cache.
     "###
     );
 

crates/uv/tests/workspace.rs

@@ -1011,7 +1011,7 @@ fn workspace_inherit_sources() -> Result<()> {
       ╰─▶ Because library was not found in the cache and leaf depends on library, we can conclude that leaf's requirements are unsatisfiable.
           And because your workspace requires leaf, we can conclude that your workspace's requirements are unsatisfiable.
 
-          hint: Packages were unavailable because the network was disabled
+          hint: Packages were unavailable because the network was disabled. When the network is disabled, registry packages may only be read from the cache.
     "###
     );