Use a no-op timestamp for exclude-newer in lockfiles when a relative value is configured

crates/uv-resolver/src/exclude_newer.rs

@@ -545,7 +545,9 @@ impl ExcludeNewer {
         match (&self.global, &other.global) {
             (Some(self_global), Some(other_global)) => {
                 if let Some(change) = compare_exclude_newer_value(self_global, other_global) {
-                    return Some(ExcludeNewerChange::GlobalChanged(change));
+                    if !change.is_relative_timestamp_change() {
+                        return Some(ExcludeNewerChange::GlobalChanged(change));
+                    }
                 }
             }
             (None, Some(global)) => {

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

@@ -1161,10 +1161,18 @@ impl Lock {
             if !exclude_newer.is_empty() {
                 // Always serialize global exclude-newer as a string
                 if let Some(global) = &exclude_newer.global {
-                    options_table.insert("exclude-newer", value(global.to_string()));
-                    // Serialize the original span if present
                     if let Some(span) = global.span() {
+                        // When a relative span is present, write a no-op timestamp
+                        // for backwards compatibility with older versions of uv that
+                        // don't understand `exclude-newer-span`.
+                        let mut noop = value("0001-01-01T00:00:00Z");
+                        if let Item::Value(ref mut v) = noop {
+                            v.decor_mut().set_suffix(" # This has no effect and is included for backwards compatibility when using relative exclude-newer values.");
+                        }
+                        options_table.insert("exclude-newer", noop);
                         options_table.insert("exclude-newer-span", value(span.to_string()));
+                    } else {
+                        options_table.insert("exclude-newer", value(global.to_string()));
                     }
                 }
 
@@ -2349,10 +2357,13 @@ struct ExcludeNewerWire {
 
 impl From<ExcludeNewerWire> for ExcludeNewer {
     fn from(wire: ExcludeNewerWire) -> Self {
+        let global = match (wire.exclude_newer, wire.exclude_newer_span) {
+            (Some(timestamp), span) => Some(ExcludeNewerValue::new(timestamp, span)),
+            (None, Some(span)) => Some(ExcludeNewerValue::new(Timestamp::UNIX_EPOCH, Some(span))),
+            (None, None) => None,
+        };
         Self {
-            global: wire
-                .exclude_newer
-                .map(|timestamp| ExcludeNewerValue::new(timestamp, wire.exclude_newer_span)),
+            global,
             package: wire.exclude_newer_package,
         }
     }

crates/uv/tests/it/lock_exclude_newer_relative.rs

@@ -48,7 +48,7 @@ fn lock_exclude_newer_relative() -> Result<()> {
     requires-python = ">=3.12"
 
     [options]
-    exclude-newer = "2024-04-10T00:00:00Z"
+    exclude-newer = "0001-01-01T00:00:00Z" # This has no effect and is included for backwards compatibility when using relative exclude-newer values.
     exclude-newer-span = "P3W"
 
     [[package]]
@@ -116,7 +116,7 @@ fn lock_exclude_newer_relative() -> Result<()> {
     requires-python = ">=3.12"
 
     [options]
-    exclude-newer = "2024-04-17T00:00:00Z"
+    exclude-newer = "0001-01-01T00:00:00Z" # This has no effect and is included for backwards compatibility when using relative exclude-newer values.
     exclude-newer-span = "P2W"
 
     [[package]]
@@ -165,7 +165,7 @@ fn lock_exclude_newer_relative() -> Result<()> {
     requires-python = ">=3.12"
 
     [options]
-    exclude-newer = "2024-05-18T00:00:00Z"
+    exclude-newer = "0001-01-01T00:00:00Z" # This has no effect and is included for backwards compatibility when using relative exclude-newer values.
     exclude-newer-span = "P2W"
 
     [[package]]
@@ -560,7 +560,7 @@ fn lock_exclude_newer_relative_pyproject() -> Result<()> {
     requires-python = ">=3.12"
 
     [options]
-    exclude-newer = "2024-04-10T00:00:00Z"
+    exclude-newer = "0001-01-01T00:00:00Z" # This has no effect and is included for backwards compatibility when using relative exclude-newer values.
     exclude-newer-span = "P3W"
 
     [[package]]
@@ -714,7 +714,7 @@ fn lock_exclude_newer_relative_global_and_package() -> Result<()> {
     requires-python = ">=3.12"
 
     [options]
-    exclude-newer = "2024-04-10T00:00:00Z"
+    exclude-newer = "0001-01-01T00:00:00Z" # This has no effect and is included for backwards compatibility when using relative exclude-newer values.
     exclude-newer-span = "P3W"
 
     [options.exclude-newer-package]
@@ -907,7 +907,7 @@ fn lock_exclude_newer_relative_global_and_package() -> Result<()> {
     requires-python = ">=3.12"
 
     [options]
-    exclude-newer = "2024-04-10T00:00:00Z"
+    exclude-newer = "0001-01-01T00:00:00Z" # This has no effect and is included for backwards compatibility when using relative exclude-newer values.
     exclude-newer-span = "P3W"
 
     [options.exclude-newer-package]
@@ -1235,7 +1235,7 @@ fn lock_exclude_newer_relative_no_timestamp_in_lockfile() -> Result<()> {
     requires-python = ">=3.12"
 
     [options]
-    exclude-newer = "2024-04-10T00:00:00Z"
+    exclude-newer = "0001-01-01T00:00:00Z" # This has no effect and is included for backwards compatibility when using relative exclude-newer values.
     exclude-newer-span = "P3W"
 
     [[package]]
@@ -1260,7 +1260,7 @@ fn lock_exclude_newer_relative_no_timestamp_in_lockfile() -> Result<()> {
     "#);
 
     // Manually remove the exclude-newer timestamp from the lockfile, leaving the span.
-    let lock = lock.replace("exclude-newer = \"2024-04-10T00:00:00Z\"\n", "");
+    let lock = lock.replace("exclude-newer = \"0001-01-01T00:00:00Z\" # This has no effect and is included for backwards compatibility when using relative exclude-newer values.\n", "");
     context.temp_dir.child("uv.lock").write_str(&lock)?;
 
     // The lockfile now has no exclude-newer, but `pyproject.toml` still configures one,
@@ -1274,19 +1274,17 @@ fn lock_exclude_newer_relative_no_timestamp_in_lockfile() -> Result<()> {
     ----- stdout -----
 
     ----- stderr -----
-    Resolving despite existing lockfile due to addition of global exclude newer 2024-04-10T00:00:00Z
     Resolved 2 packages in [TIME]
     ");
 
-    // The lockfile should have exclude-newer restored.
+    // The lockfile retains the span but no timestamp since no re-resolution occurred.
     let lock = context.read("uv.lock");
     assert_snapshot!(lock, @r#"
     version = 1
     revision = 3
     requires-python = ">=3.12"
 
     [options]
-    exclude-newer = "2024-04-10T00:00:00Z"
     exclude-newer-span = "P3W"
 
     [[package]]