switch to jiff from chrono (#6205)

This PR migrates uv's use of `chrono` to `jiff`. I did most of this work a while back as one of my tests to ensure Jiff could actually be used in a real world project. I decided to revive this because I noticed that `reqwest-retry` dropped its Chrono dependency, which is I believe the only other thing requiring Chrono in uv. (Although, we use a fork of `reqwest-middleware` at present, and that hasn't been updated to latest upstream yet. I wasn't quite sure of the process we have for that.) In course of doing this, I actually made two changes to uv: First is that the lock file now writes an RFC 3339 timestamp for `exclude-newer`. Previously, we were using Chrono's `Display` implementation for this which is a non-standard but "human readable" format. I think the right thing to do here is an RFC 3339 timestamp. Second is that, in addition to an RFC 3339 timestamp, `--exclude-newer` used to accept a "UTC date." But this PR changes it to a "local date." That is, a date in the user's system configured time zone. I think this makes more sense than a UTC date, but one alternative is to drop support for a date and just rely on an RFC 3339 timestamp. The main motivation here is that automatically assuming UTC is often somewhat confusing, since just writing an unqualified date like `2024-08-19` is often assumed to be interpreted relative to the writer's "local" time.
2025-11-01 20:31:12 +00:00 · 2024-08-19 10:36:00 -07:00 · 2024-08-19 10:36:00 -07:00 · 33480d61eb
commit 33480d61eb
parent c8f27a3978
38 changed files with 285 additions and 213 deletions
--- a/Cargo.lock
+++ b/Cargo.lock
@ -388,12 +388,12 @@ name = "bench"
 version = "0.0.0"
 dependencies = [
 "anyhow",
- "chrono",
 "codspeed-criterion-compat",
 "criterion",
 "distribution-filename",
 "distribution-types",
 "install-wheel-rs",
+ "jiff",
 "pep440_rs",
 "pep508_rs",
 "platform-tags",
@ -656,10 +656,8 @@ checksum = "a21f936df1771bf62b77f047b726c4625ff2e8aa607c01ec06e5a05bd8463401"
 dependencies = [
 "android-tzdata",
 "iana-time-zone",
- "js-sys",
 "num-traits",
 "serde",
- "wasm-bindgen",
 "windows-targets 0.52.6",
 ]

@ -1105,6 +1103,7 @@ dependencies = [
 "distribution-filename",
 "fs-err",
 "itertools 0.13.0",
+ "jiff",
 "pep440_rs",
 "pep508_rs",
 "platform-tags",
@ -1926,6 +1925,32 @@ version = "1.0.11"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "49f1f14873335454500d59611f1cf4a4b0f786f9ac11f4312a78e4cf2566695b"

+[[package]]
+name = "jiff"
+version = "0.1.7"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94fda28c0e0f7e5ac1e40c34a06393ae6ecf4c9ce6b6421a2217a32680bb8038"
+dependencies = [
+ "jiff-tzdb-platform",
+ "serde",
+ "windows-sys 0.59.0",
+]
+
+[[package]]
+name = "jiff-tzdb"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "05fac328b3df1c0f18a3c2ab6cb7e06e4e549f366017d796e3e66b6d6889abe6"
+
+[[package]]
+name = "jiff-tzdb-platform"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f8da387d5feaf355954c2c122c194d6df9c57d865125a67984bb453db5336940"
+dependencies = [
+ "jiff-tzdb",
+]
+
 [[package]]
 name = "jobserver"
 version = "0.1.32"
@ -2829,10 +2854,10 @@ name = "pypi-types"
 version = "0.0.1"
 dependencies = [
 "anyhow",
- "chrono",
 "distribution-filename",
 "indexmap",
 "itertools 0.13.0",
+ "jiff",
 "mailparse",
 "pep440_rs",
 "pep508_rs",
@ -4472,7 +4497,6 @@ dependencies = [
 "base64 0.22.1",
 "byteorder",
 "cache-key",
- "chrono",
 "clap",
 "distribution-types",
 "filetime",
@ -4486,6 +4510,7 @@ dependencies = [
 "insta",
 "install-wheel-rs",
 "itertools 0.13.0",
+ "jiff",
 "miette",
 "mimalloc",
 "owo-colors",
@ -4648,7 +4673,6 @@ dependencies = [
 "async_http_range_reader",
 "async_zip",
 "cache-key",
- "chrono",
 "distribution-filename",
 "distribution-types",
 "fs-err",
@ -4661,6 +4685,7 @@ dependencies = [
 "insta",
 "install-wheel-rs",
 "itertools 0.13.0",
+ "jiff",
 "pep440_rs",
 "pep508_rs",
 "platform-tags",
@ -5052,7 +5077,6 @@ version = "0.0.1"
 dependencies = [
 "anyhow",
 "cache-key",
- "chrono",
 "clap",
 "dashmap",
 "derivative",
@ -5064,6 +5088,7 @@ dependencies = [
 "insta",
 "install-wheel-rs",
 "itertools 0.13.0",
+ "jiff",
 "once-map",
 "owo-colors",
 "pep440_rs",
--- a/Cargo.toml
+++ b/Cargo.toml
@ -70,7 +70,6 @@ base64 = { version = "0.22.0" }
 boxcar = { version = "0.2.5" }
 cachedir = { version = "0.3.1" }
 cargo-util = { version = "0.2.8" }
-chrono = { version = "0.4.31" }
 clap = { version = "4.5.9" }
 clap_complete_command = { version = "0.6.0" }
 configparser = { version = "3.0.4" }
@ -98,6 +97,7 @@ indexmap = { version = "2.2.5" }
 indicatif = { version = "0.17.7" }
 indoc = { version = "2.0.4" }
 itertools = { version = "0.13.0" }
+jiff = { version = "0.1.6", features = ["serde"] }
 junction = { version = "1.0.0" }
 mailparse = { version = "0.15.0" }
 md-5 = { version = "0.10.6" }
--- a/README.md
+++ b/README.md
@ -491,7 +491,8 @@ cases, but may lose fidelity for complex package and platform combinations._
 uv supports an `--exclude-newer` option to limit resolution to distributions published before a
 specific date, allowing reproduction of installations regardless of new package releases. The date
 may be specified as an [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamp (e.g.,
-`2006-12-02T02:07:43Z`) or UTC date in the same format (e.g., `2006-12-02`).
+`2006-12-02T02:07:43Z`) or a local date in the same format (e.g., `2006-12-02`) in your system's
+configured time zone.

 Note the package index must support the `upload-time` field as specified in
 [`PEP 700`](https://peps.python.org/pep-0700/). If the field is not present for a given
--- a/crates/bench/Cargo.toml
+++ b/crates/bench/Cargo.toml
@ -46,9 +46,9 @@ uv-resolver = { workspace = true }
 uv-types = { workspace = true }

 anyhow = { workspace = true }
-chrono = { workspace = true }
 codspeed-criterion-compat = { version = "2.6.0", default-features = false, optional = true }
 criterion = { version = "0.5.1", default-features = false, features = ["async_tokio"] }
+jiff = { workspace = true }
 tokio = { workspace = true }

 [features]
--- a/crates/bench/benches/uv.rs
+++ b/crates/bench/benches/uv.rs
@ -82,7 +82,6 @@ mod resolver {
    use std::sync::LazyLock;

    use anyhow::Result;
-    use chrono::NaiveDate;

    use distribution_types::IndexLocations;
    use install_wheel_rs::linker::LinkMode;
@ -144,11 +143,10 @@ mod resolver {
        let concurrency = Concurrency::default();
        let config_settings = ConfigSettings::default();
        let exclude_newer = Some(
-            NaiveDate::from_ymd_opt(2024, 8, 8)
+            jiff::civil::date(2024, 8, 8)
+                .to_zoned(jiff::tz::TimeZone::UTC)
                .unwrap()
-                .and_hms_opt(0, 0, 0)
-                .unwrap()
-                .and_utc()
+                .timestamp()
                .into(),
        );
        let flat_index = FlatIndex::default();
--- a/crates/distribution-types/Cargo.toml
+++ b/crates/distribution-types/Cargo.toml
@ -26,6 +26,7 @@ uv-normalize = { workspace = true }
 anyhow = { workspace = true }
 fs-err = { workspace = true }
 itertools = { workspace = true }
+jiff = { workspace = true }
 rkyv = { workspace = true }
 schemars = { workspace = true, optional = true }
 serde = { workspace = true, features = ["derive"] }
--- a/crates/distribution-types/src/file.rs
+++ b/crates/distribution-types/src/file.rs
@ -3,6 +3,7 @@ use std::fmt::{self, Display, Formatter};
 use std::path::PathBuf;
 use std::str::FromStr;

+use jiff::Timestamp;
 use serde::{Deserialize, Serialize};
 use url::Url;

@ -31,7 +32,7 @@ pub struct File {
    pub hashes: Vec<HashDigest>,
    pub requires_python: Option<VersionSpecifiers>,
    pub size: Option<u64>,
-    // N.B. We don't use a chrono DateTime<Utc> here because it's a little
+    // N.B. We don't use a Jiff timestamp here because it's a little
    // annoying to do so with rkyv. Since we only use this field for doing
    // comparisons in testing, we just store it as a UTC timestamp in
    // milliseconds.
@ -57,7 +58,7 @@ impl File {
                .transpose()
                .map_err(|err| FileConversionError::RequiresPython(err.line().clone(), err))?,
            size: file.size,
-            upload_time_utc_ms: file.upload_time.map(|dt| dt.timestamp_millis()),
+            upload_time_utc_ms: file.upload_time.map(Timestamp::as_millisecond),
            url: match Url::parse(&file.url) {
                Ok(url) => FileLocation::AbsoluteUrl(url.into()),
                Err(_) => FileLocation::RelativeUrl(base.to_string(), file.url),
--- a/crates/pypi-types/Cargo.toml
+++ b/crates/pypi-types/Cargo.toml
@ -20,9 +20,9 @@ uv-fs = { workspace = true, features = ["serde"] }
 uv-git = { workspace = true }
 uv-normalize = { workspace = true }

-chrono = { workspace = true, features = ["serde"] }
 indexmap = { workspace = true, features = ["serde"] }
 itertools = { workspace = true }
+jiff = { workspace = true, features = ["serde"] }
 mailparse = { workspace = true }
 regex = { workspace = true }
 rkyv = { workspace = true }
--- a/crates/pypi-types/src/simple_json.rs
+++ b/crates/pypi-types/src/simple_json.rs
@ -1,6 +1,6 @@
 use std::str::FromStr;

-use chrono::{DateTime, Utc};
+use jiff::Timestamp;
 use serde::{Deserialize, Deserializer, Serialize};

 use pep440_rs::{VersionSpecifiers, VersionSpecifiersParseError};
@ -51,7 +51,7 @@ pub struct File {
    #[serde(default, deserialize_with = "deserialize_version_specifiers_lenient")]
    pub requires_python: Option<Result<VersionSpecifiers, VersionSpecifiersParseError>>,
    pub size: Option<u64>,
-    pub upload_time: Option<DateTime<Utc>>,
+    pub upload_time: Option<Timestamp>,
    pub url: String,
    pub yanked: Option<Yanked>,
 }
--- a/crates/uv-cli/src/lib.rs
+++ b/crates/uv-cli/src/lib.rs
@ -2009,8 +2009,8 @@ pub struct VenvArgs {

    /// Limit candidate packages to those that were uploaded prior to the given date.
    ///
-    /// Accepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and UTC dates in the same
-    /// format (e.g., `2006-12-02`).
+    /// Accepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and local dates in the same
+    /// format (e.g., `2006-12-02`) in your system's configured time zone.
    #[arg(long, env = "UV_EXCLUDE_NEWER")]
    pub exclude_newer: Option<ExcludeNewer>,

@ -3314,8 +3314,8 @@ pub struct InstallerArgs {

    /// Limit candidate packages to those that were uploaded prior to the given date.
    ///
-    /// Accepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and UTC dates in the same
-    /// format (e.g., `2006-12-02`).
+    /// Accepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and local dates in the same
+    /// format (e.g., `2006-12-02`) in your system's configured time zone.
    #[arg(long, env = "UV_EXCLUDE_NEWER", help_heading = "Resolver options")]
    pub exclude_newer: Option<ExcludeNewer>,

@ -3488,8 +3488,8 @@ pub struct ResolverArgs {

    /// Limit candidate packages to those that were uploaded prior to the given date.
    ///
-    /// Accepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and UTC dates in the same
-    /// format (e.g., `2006-12-02`).
+    /// Accepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and local dates in the same
+    /// format (e.g., `2006-12-02`) in your system's configured time zone.
    #[arg(long, env = "UV_EXCLUDE_NEWER", help_heading = "Resolver options")]
    pub exclude_newer: Option<ExcludeNewer>,

@ -3660,8 +3660,8 @@ pub struct ResolverInstallerArgs {

    /// Limit candidate packages to those that were uploaded prior to the given date.
    ///
-    /// Accepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and UTC dates in the same
-    /// format (e.g., `2006-12-02`).
+    /// Accepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and local dates in the same
+    /// format (e.g., `2006-12-02`) in your system's configured time zone.
    #[arg(long, env = "UV_EXCLUDE_NEWER", help_heading = "Resolver options")]
    pub exclude_newer: Option<ExcludeNewer>,

--- a/crates/uv-client/Cargo.toml
+++ b/crates/uv-client/Cargo.toml
@ -27,12 +27,12 @@ anyhow = { workspace = true }
 async-trait = { workspace = true }
 async_http_range_reader = { workspace = true }
 async_zip = { workspace = true, features = ["tokio"] }
-chrono = { workspace = true }
 fs-err = { workspace = true, features = ["tokio"] }
 futures = { workspace = true }
 html-escape = { workspace = true }
 http = { workspace = true }
 itertools = { workspace = true }
+jiff = { workspace = true }
 reqwest = { workspace = true }
 reqwest-middleware = { workspace = true }
 reqwest-retry = { workspace = true }
--- a/crates/uv-client/src/httpcache/mod.rs
+++ b/crates/uv-client/src/httpcache/mod.rs
@ -1363,13 +1363,13 @@ fn unix_timestamp(time: SystemTime) -> u64 {
 }

 fn rfc2822_to_unix_timestamp(s: &str) -> Option<u64> {
-    rfc2822_to_datetime(s).and_then(|dt| u64::try_from(dt.timestamp()).ok())
+    rfc2822_to_datetime(s).and_then(|timestamp| u64::try_from(timestamp.as_second()).ok())
 }

-fn rfc2822_to_datetime(s: &str) -> Option<chrono::DateTime<chrono::Utc>> {
-    chrono::DateTime::parse_from_rfc2822(s)
+fn rfc2822_to_datetime(s: &str) -> Option<jiff::Timestamp> {
+    jiff::fmt::rfc2822::DateTimeParser::new()
+        .parse_timestamp(s)
        .ok()
-        .map(|dt| dt.to_utc())
 }

 fn unix_timestamp_to_header(seconds: u64) -> Option<HeaderValue> {
@ -1377,11 +1377,19 @@ fn unix_timestamp_to_header(seconds: u64) -> Option<HeaderValue> {
 }

 fn unix_timestamp_to_rfc2822(seconds: u64) -> Option<String> {
-    unix_timestamp_to_datetime(seconds).map(|dt| dt.to_rfc2822())
+    use jiff::fmt::rfc2822::DateTimePrinter;
+
+    unix_timestamp_to_datetime(seconds).and_then(|timestamp| {
+        let mut buf = String::new();
+        DateTimePrinter::new()
+            .print_timestamp(&timestamp, &mut buf)
+            .ok()?;
+        Some(buf)
+    })
 }

-fn unix_timestamp_to_datetime(seconds: u64) -> Option<chrono::DateTime<chrono::Utc>> {
-    chrono::DateTime::from_timestamp(i64::try_from(seconds).ok()?, 0)
+fn unix_timestamp_to_datetime(seconds: u64) -> Option<jiff::Timestamp> {
+    jiff::Timestamp::from_second(i64::try_from(seconds).ok()?).ok()
 }

 fn parse_seconds(value: &[u8]) -> Option<u64> {
--- a/crates/uv-resolver/Cargo.toml
+++ b/crates/uv-resolver/Cargo.toml
@ -36,7 +36,6 @@ uv-warnings = { workspace = true }
 uv-workspace = { workspace = true }

 anyhow = { workspace = true }
-chrono = { workspace = true }
 clap = { workspace = true, features = ["derive"], optional = true }
 dashmap = { workspace = true }
 derivative = { workspace = true }
@ -44,6 +43,7 @@ either = { workspace = true }
 futures = { workspace = true }
 indexmap = { workspace = true }
 itertools = { workspace = true }
+jiff = { workspace = true, features = ["serde"] }
 owo-colors = { workspace = true }
 petgraph = { workspace = true }
 pubgrub = { workspace = true }
--- a/crates/uv-resolver/src/exclude_newer.rs
+++ b/crates/uv-resolver/src/exclude_newer.rs
@ -1,21 +1,21 @@
 use std::str::FromStr;

-use chrono::{DateTime, Days, NaiveDate, NaiveTime, Utc};
+use jiff::{tz::TimeZone, Timestamp, ToSpan};

 /// A timestamp that excludes files newer than it.
 #[derive(Debug, Copy, Clone, PartialEq, Eq, serde::Deserialize, serde::Serialize)]
-pub struct ExcludeNewer(DateTime<Utc>);
+pub struct ExcludeNewer(Timestamp);

 impl ExcludeNewer {
    /// Returns the timestamp in milliseconds.
    pub fn timestamp_millis(&self) -> i64 {
-        self.0.timestamp_millis()
+        self.0.as_millisecond()
    }
 }

-impl From<DateTime<Utc>> for ExcludeNewer {
-    fn from(datetime: DateTime<Utc>) -> Self {
-        Self(datetime)
+impl From<Timestamp> for ExcludeNewer {
+    fn from(timestamp: Timestamp) -> Self {
+        Self(timestamp)
    }
 }

@ -24,25 +24,38 @@ impl FromStr for ExcludeNewer {

    /// Parse an [`ExcludeNewer`] from a string.
    ///
-    /// Accepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and UTC dates in the same
+    /// Accepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and local dates in the same
    /// format (e.g., `2006-12-02`).
    fn from_str(input: &str) -> Result<Self, Self::Err> {
-        let date_err = match NaiveDate::from_str(input) {
-            Ok(date) => {
-                // Midnight that day is 00:00:00 the next day
-                return Ok(Self(
-                    (date + Days::new(1)).and_time(NaiveTime::MIN).and_utc(),
-                ));
-            }
-            Err(err) => err,
-        };
-        let datetime_err = match DateTime::parse_from_rfc3339(input) {
-            Ok(datetime) => return Ok(Self(datetime.with_timezone(&Utc))),
-            Err(err) => err,
-        };
-        Err(format!(
-            "`{input}` is neither a valid date ({date_err}) nor a valid datetime ({datetime_err})"
-        ))
+        // NOTE(burntsushi): Previously, when using Chrono, we tried
+        // to parse as a date first, then a timestamp, and if both
+        // failed, we combined both of the errors into one message.
+        // But in Jiff, if an RFC 3339 timestamp could be parsed, then
+        // it must necessarily be the case that a date can also be
+        // parsed. So we can collapse the error cases here. That is,
+        // if we fail to parse a timestamp and a date, then it should
+        // be sufficient to just report the error from parsing the date.
+        // If someone tried to write a timestamp but committed an error
+        // in the non-date portion, the date parsing below will still
+        // report a holistic error that will make sense to the user.
+        // (I added a snapshot test for that case.)
+        if let Ok(timestamp) = input.parse::<Timestamp>() {
+            return Ok(Self(timestamp));
+        }
+        let date = input
+            .parse::<jiff::civil::Date>()
+            .map_err(|err| format!("`{input}` could not be parsed as a valid date: {err}"))?;
+        let timestamp = date
+            .checked_add(1.day())
+            .and_then(|date| date.to_zoned(TimeZone::system()))
+            .map(|zdt| zdt.timestamp())
+            .map_err(|err| {
+                format!(
+                    "`{input}` parsed to date `{date}`, but could not \
+                     be converted to a timestamp: {err}",
+                )
+            })?;
+        Ok(Self(timestamp))
    }
 }

@ -68,7 +81,7 @@ impl schemars::JsonSchema for ExcludeNewer {
                ..schemars::schema::StringValidation::default()
            })),
            metadata: Some(Box::new(schemars::schema::Metadata {
-                description: Some("Exclude distributions uploaded after the given timestamp.\n\nAccepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and UTC dates in the same format (e.g., `2006-12-02`).".to_string()),
+                description: Some("Exclude distributions uploaded after the given timestamp.\n\nAccepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and local dates in the same format (e.g., `2006-12-02`).".to_string()),
              ..schemars::schema::Metadata::default()
            })),
            ..schemars::schema::SchemaObject::default()
--- a/crates/uv-settings/src/settings.rs
+++ b/crates/uv-settings/src/settings.rs
@ -383,7 +383,8 @@ pub struct ResolverInstallerOptions {
    /// Limit candidate packages to those that were uploaded prior to the given date.
    ///
    /// Accepts both [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamps (e.g.,
-    /// `2006-12-02T02:07:43Z`) and UTC dates in the same format (e.g., `2006-12-02`).
+    /// `2006-12-02T02:07:43Z`) and local dates in the same format (e.g., `2006-12-02`) in your
+    /// system's configured time zone.
    #[option(
        default = "None",
        value_type = "str",
@ -978,7 +979,8 @@ pub struct PipOptions {
    /// Limit candidate packages to those that were uploaded prior to the given date.
    ///
    /// Accepts both [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamps (e.g.,
-    /// `2006-12-02T02:07:43Z`) and UTC dates in the same format (e.g., `2006-12-02`).
+    /// `2006-12-02T02:07:43Z`) and local dates in the same format (e.g., `2006-12-02`) in your
+    /// system's configured time zone.
    #[option(
        default = "None",
        value_type = "str",
--- a/crates/uv/Cargo.toml
+++ b/crates/uv/Cargo.toml
@ -47,7 +47,6 @@ uv-workspace = { workspace = true }
 anstream = { workspace = true }
 anyhow = { workspace = true }
 axoupdater = { workspace = true, features = ["github_releases", "tokio"], optional = true }
-chrono = { workspace = true }
 clap = { workspace = true, features = ["derive", "string", "wrap_help"] }
 flate2 = { workspace = true, default-features = false }
 fs-err = { workspace = true, features = ["tokio"] }
@ -56,6 +55,7 @@ indexmap = { workspace = true }
 indicatif = { workspace = true }
 indoc = { workspace = true }
 itertools = { workspace = true }
+jiff = { workspace = true }
 miette = { workspace = true, features = ["fancy"] }
 owo-colors = { workspace = true }
 rayon = { workspace = true }
--- a/crates/uv/src/logging.rs
+++ b/crates/uv/src/logging.rs
@ -3,7 +3,7 @@ use std::str::FromStr;

 use anstream::ColorChoice;
 use anyhow::Context;
-use chrono::Utc;
+use jiff::Timestamp;
 use owo_colors::OwoColorize;
 use tracing::{Event, Subscriber};
 #[cfg(feature = "tracing-durations-export")]
@ -54,9 +54,9 @@ where

        if self.display_timestamp {
            if ansi {
-                write!(writer, "{} ", Utc::now().dimmed())?;
+                write!(writer, "{} ", Timestamp::now().dimmed())?;
            } else {
-                write!(writer, "{} ", Utc::now())?;
+                write!(writer, "{} ", Timestamp::now())?;
            }
        }

--- a/crates/uv/tests/branching_urls.rs
+++ b/crates/uv/tests/branching_urls.rs
@ -214,7 +214,7 @@ fn root_package_splits_transitive_too() -> Result<()> {
    ]

    [options]
-    exclude-newer = "2024-03-25 00:00:00 UTC"
+    exclude-newer = "2024-03-25T00:00:00Z"

    [[package]]
    name = "a"
@ -409,7 +409,7 @@ fn root_package_splits_other_dependencies_too() -> Result<()> {
    ]

    [options]
-    exclude-newer = "2024-03-25 00:00:00 UTC"
+    exclude-newer = "2024-03-25T00:00:00Z"

    [[package]]
    name = "a"
@ -570,7 +570,7 @@ fn branching_between_registry_and_direct_url() -> Result<()> {
    ]

    [options]
-    exclude-newer = "2024-03-25 00:00:00 UTC"
+    exclude-newer = "2024-03-25T00:00:00Z"

    [[package]]
    name = "a"
@ -655,7 +655,7 @@ fn branching_urls_of_different_sources_disjoint() -> Result<()> {
    ]

    [options]
-    exclude-newer = "2024-03-25 00:00:00 UTC"
+    exclude-newer = "2024-03-25T00:00:00Z"

    [[package]]
    name = "a"
@ -778,7 +778,7 @@ fn dont_pre_visit_url_packages() -> Result<()> {
    requires-python = ">=3.11, <3.13"

    [options]
-    exclude-newer = "2024-03-25 00:00:00 UTC"
+    exclude-newer = "2024-03-25T00:00:00Z"

    [[package]]
    name = "a"
--- a/crates/uv/tests/edit.rs
+++ b/crates/uv/tests/edit.rs
@ -71,7 +71,7 @@ fn add_registry() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -229,7 +229,7 @@ fn add_git() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -361,7 +361,7 @@ fn add_git_private_source() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -460,7 +460,7 @@ fn add_git_private_raw() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -639,7 +639,7 @@ fn add_git_raw() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -861,7 +861,7 @@ fn add_unnamed() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -959,7 +959,7 @@ fn add_remove_dev() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -1081,7 +1081,7 @@ fn add_remove_dev() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -1168,7 +1168,7 @@ fn add_remove_optional() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -1289,7 +1289,7 @@ fn add_remove_optional() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -1415,7 +1415,7 @@ fn add_remove_workspace() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        members = [
@ -1498,7 +1498,7 @@ fn add_remove_workspace() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        members = [
@ -1615,7 +1615,7 @@ fn add_workspace_editable() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        members = [
@ -1821,7 +1821,7 @@ fn update() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "certifi"
@ -2326,7 +2326,7 @@ fn add_no_clean() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -2462,7 +2462,7 @@ fn remove_registry() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -3082,7 +3082,7 @@ fn add_lower_bound_optional() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -3294,7 +3294,7 @@ fn add_virtual() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
--- a/crates/uv/tests/lock.rs
+++ b/crates/uv/tests/lock.rs
@ -52,7 +52,7 @@ fn lock_wheel_registry() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -267,7 +267,7 @@ fn lock_sdist_git() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -364,7 +364,7 @@ fn lock_sdist_git() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -422,7 +422,7 @@ fn lock_sdist_git() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -480,7 +480,7 @@ fn lock_sdist_git() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -542,7 +542,7 @@ fn lock_sdist_git_subdirectory() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "example-pkg-a"
@ -629,7 +629,7 @@ fn lock_sdist_git_pep508() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -694,7 +694,7 @@ fn lock_sdist_git_pep508() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -748,7 +748,7 @@ fn lock_sdist_git_pep508() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -802,7 +802,7 @@ fn lock_sdist_git_pep508() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -863,7 +863,7 @@ fn lock_wheel_url() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -1010,7 +1010,7 @@ fn lock_sdist_url() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -1146,7 +1146,7 @@ fn lock_project_extra() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -1411,7 +1411,7 @@ fn lock_dependency_extra() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "blinker"
@ -1616,7 +1616,7 @@ fn lock_conditional_dependency_extra() -> Result<()> {
        ]

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "certifi"
@ -1898,7 +1898,7 @@ fn lock_dependency_non_existent_extra() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "blinker"
@ -2082,7 +2082,7 @@ fn lock_upgrade_log() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -2165,7 +2165,7 @@ fn lock_upgrade_log() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "markupsafe"
@ -2257,7 +2257,7 @@ fn lock_upgrade_log_multi_version() -> Result<()> {
        ]

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "markupsafe"
@ -2340,7 +2340,7 @@ fn lock_upgrade_log_multi_version() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "markupsafe"
@ -2414,7 +2414,7 @@ fn lock_preference() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -2474,7 +2474,7 @@ fn lock_preference() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -2521,7 +2521,7 @@ fn lock_preference() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -2575,7 +2575,7 @@ fn lock_git_sha() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -2626,7 +2626,7 @@ fn lock_git_sha() -> Result<()> {
        ----- stderr -----
        warning: `uv lock` is experimental and may change without warning
        Resolved 2 packages in [TIME]
-        "###);
+    "###);

    let lock = fs_err::read_to_string(context.temp_dir.join("uv.lock")).unwrap();

@ -2641,7 +2641,7 @@ fn lock_git_sha() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -2740,7 +2740,7 @@ fn lock_requires_python() -> Result<()> {
        requires-python = ">=3.7"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "attrs"
@ -2892,7 +2892,7 @@ fn lock_requires_python() -> Result<()> {
        requires-python = ">=3.7.9"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "attrs"
@ -3034,7 +3034,7 @@ fn lock_requires_python() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "attrs"
@ -3178,7 +3178,7 @@ fn lock_requires_python_wheels() -> Result<()> {
        requires-python = "==3.12.*"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "frozenlist"
@ -3263,7 +3263,7 @@ fn lock_requires_python_wheels() -> Result<()> {
        requires-python = "==3.11.*"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "frozenlist"
@ -3373,7 +3373,7 @@ fn lock_requires_python_star() -> Result<()> {
        requires-python = "==3.11.*"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "attrs"
@ -3497,7 +3497,7 @@ fn lock_requires_python_pre() -> Result<()> {
        requires-python = ">=3.11"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "attrs"
@ -3620,7 +3620,7 @@ fn lock_requires_python_unbounded() -> Result<()> {
        requires-python = "<=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -3718,7 +3718,7 @@ fn lock_python_version_marker_complement() -> Result<()> {
        ]

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "attrs"
@ -3824,7 +3824,7 @@ fn lock_dev() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -3942,7 +3942,7 @@ fn lock_conditional_unconditional() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -4021,7 +4021,7 @@ fn lock_multiple_markers() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -4140,7 +4140,7 @@ fn lock_relative_and_absolute_paths() -> Result<()> {
        requires-python = ">=3.11, <3.13"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "a"
@ -4222,7 +4222,7 @@ fn lock_cycles() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "argparse"
@ -4427,7 +4427,7 @@ fn lock_new_extras() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "certifi"
@ -4552,7 +4552,7 @@ fn lock_new_extras() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "certifi"
@ -4799,7 +4799,7 @@ fn lock_resolution_mode() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -4882,7 +4882,7 @@ fn lock_resolution_mode() -> Result<()> {

        [options]
        resolution-mode = "lowest-direct"
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -5047,7 +5047,7 @@ fn lock_same_version_multiple_urls() -> Result<()> {
        ]

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -5264,7 +5264,7 @@ fn lock_exclusion() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "child"
@ -5383,7 +5383,7 @@ fn lock_dev_transitive() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        members = [
@ -5506,7 +5506,7 @@ fn lock_redact_https() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "foo"
@ -5657,7 +5657,7 @@ fn lock_redact_git() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "foo"
@ -5746,7 +5746,7 @@ fn lock_relative_index() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "foo"
@ -5854,7 +5854,7 @@ fn lock_no_sources() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -5928,7 +5928,7 @@ fn lock_no_sources() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -6013,7 +6013,7 @@ fn lock_migrate() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[distribution-term-we-dont-know]]
        name = "anyio"
@ -6081,7 +6081,7 @@ fn lock_migrate() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -6181,7 +6181,7 @@ fn lock_upgrade_package() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -6278,7 +6278,7 @@ fn lock_upgrade_package() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -6363,7 +6363,7 @@ fn lock_upgrade_package() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -6528,7 +6528,7 @@ fn lock_find_links_local_wheel() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -6620,7 +6620,7 @@ fn lock_find_links_local_sdist() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -6711,7 +6711,7 @@ fn lock_find_links_http_wheel() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "packaging"
@ -6805,7 +6805,7 @@ fn lock_find_links_http_sdist() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "packaging"
@ -7021,7 +7021,7 @@ fn lock_sources_url() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -7160,7 +7160,7 @@ fn lock_sources_archive() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -7314,7 +7314,7 @@ fn lock_sources_source_tree() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -7447,7 +7447,7 @@ fn lock_editable() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        members = [
@ -7530,7 +7530,7 @@ fn lock_editable() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        members = [
@ -7691,7 +7691,7 @@ fn lock_mixed_extras() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        members = [
@ -7887,7 +7887,7 @@ fn lock_transitive_extra() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        members = [
@ -8083,7 +8083,7 @@ fn lock_mismatched_versions() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -8204,7 +8204,7 @@ fn lock_change_index() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -8251,7 +8251,7 @@ fn lock_change_index() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -8347,7 +8347,7 @@ fn lock_remove_member() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        members = [
@ -8472,7 +8472,7 @@ fn lock_remove_member() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -8530,7 +8530,7 @@ fn lock_add_member() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "project"
@ -8641,7 +8641,7 @@ fn lock_add_member() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        members = [
@ -8745,7 +8745,7 @@ fn lock_redundant_add_member() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -8852,7 +8852,7 @@ fn lock_redundant_add_member() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -8944,7 +8944,7 @@ fn lock_new_constraints() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -9053,7 +9053,7 @@ fn lock_new_constraints() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        constraints = [{ name = "anyio", specifier = "<4.3" }]
@ -9154,7 +9154,7 @@ fn lock_remove_member_virtual() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        members = [
@ -9263,7 +9263,7 @@ fn lock_remove_member_virtual() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"
        "###
        );
    });
@ -9310,7 +9310,7 @@ fn lock_rename_project() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -9393,7 +9393,7 @@ fn lock_rename_project() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "iniconfig"
@ -9445,7 +9445,7 @@ fn lock_missing_metadata() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -9496,7 +9496,7 @@ fn lock_missing_metadata() -> Result<()> {
        ----- stderr -----
        warning: `uv lock` is experimental and may change without warning
        Resolved 4 packages in [TIME]
-        "###);
+    "###);

    let lock = fs_err::read_to_string(context.temp_dir.join("uv.lock")).unwrap();

@ -9509,7 +9509,7 @@ fn lock_missing_metadata() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -9597,7 +9597,7 @@ fn lock_reorder() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
@ -9750,7 +9750,7 @@ fn lock_narrowed_python_version() -> Result<()> {
        ]

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "dependency"
@ -9854,7 +9854,7 @@ fn lock_exclude_unnecessary_python_forks() -> Result<()> {
        ]

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [[package]]
        name = "anyio"
--- a/crates/uv/tests/pip_compile.rs
+++ b/crates/uv/tests/pip_compile.rs
@ -2559,7 +2559,27 @@ fn compile_exclude_newer() -> Result<()> {
    ----- stdout -----

    ----- stderr -----
-    error: invalid value '2022-04-04+02:00' for '--exclude-newer <EXCLUDE_NEWER>': `2022-04-04+02:00` is neither a valid date (trailing input) nor a valid datetime (input contains invalid characters)
+    error: invalid value '2022-04-04+02:00' for '--exclude-newer <EXCLUDE_NEWER>': `2022-04-04+02:00` could not be parsed as a valid date: parsed value '2022-04-04', but unparsed input "+02:00" remains (expected no unparsed input)
+
+    For more information, try '--help'.
+    "###
+    );
+
+    // Check the error message for the case of
+    // an invalid timestamp that still has a
+    // valid date.
+    uv_snapshot!(context
+        .pip_compile()
+        .env_remove("UV_EXCLUDE_NEWER")
+        .arg("requirements.in")
+        .arg("--exclude-newer")
+        .arg("2022-04-04T26:00:00+00"), @r###"
+    success: false
+    exit_code: 2
+    ----- stdout -----
+
+    ----- stderr -----
+    error: invalid value '2022-04-04T26:00:00+00' for '--exclude-newer <EXCLUDE_NEWER>': `2022-04-04T26:00:00+00` could not be parsed as a valid date: failed to parse hour in time "26:00:00+00": hour is not valid: parameter 'hour' with value 26 is not in the required range of 0..=23

    For more information, try '--help'.
    "###
--- a/crates/uv/tests/snapshots/ecosystem__black-lock-file.snap
+++ b/crates/uv/tests/snapshots/ecosystem__black-lock-file.snap
@ -10,7 +10,7 @@ resolution-markers = [
 ]

 [options]
-exclude-newer = "2024-08-08 00:00:00 UTC"
+exclude-newer = "2024-08-08T00:00:00Z"

 [[package]]
 name = "aiohappyeyeballs"
--- a/crates/uv/tests/snapshots/ecosystem__github-wikidata-bot-lock-file.snap
+++ b/crates/uv/tests/snapshots/ecosystem__github-wikidata-bot-lock-file.snap
@ -10,7 +10,7 @@ resolution-markers = [
 ]

 [options]
-exclude-newer = "2024-08-08 00:00:00 UTC"
+exclude-newer = "2024-08-08T00:00:00Z"

 [[package]]
 name = "annotated-types"
--- a/crates/uv/tests/snapshots/ecosystem__home-assistant-core-lock-file.snap
+++ b/crates/uv/tests/snapshots/ecosystem__home-assistant-core-lock-file.snap
@ -6,7 +6,7 @@ version = 1
 requires-python = ">=3.12.[X]"

 [options]
-exclude-newer = "2024-08-08 00:00:00 UTC"
+exclude-newer = "2024-08-08T00:00:00Z"

 [[package]]
 name = "acme"
--- a/crates/uv/tests/snapshots/ecosystem__packse-lock-file.snap
+++ b/crates/uv/tests/snapshots/ecosystem__packse-lock-file.snap
@ -6,7 +6,7 @@ version = 1
 requires-python = ">=3.12"

 [options]
-exclude-newer = "2024-08-08 00:00:00 UTC"
+exclude-newer = "2024-08-08T00:00:00Z"

 [[package]]
 name = "anyio"
--- a/crates/uv/tests/snapshots/ecosystem__transformers-lock-file.snap
+++ b/crates/uv/tests/snapshots/ecosystem__transformers-lock-file.snap
@ -23,7 +23,7 @@ resolution-markers = [
 ]

 [options]
-exclude-newer = "2024-08-08 00:00:00 UTC"
+exclude-newer = "2024-08-08T00:00:00Z"

 [[package]]
 name = "absl-py"
--- a/crates/uv/tests/snapshots/ecosystem__warehouse-lock-file.snap
+++ b/crates/uv/tests/snapshots/ecosystem__warehouse-lock-file.snap
@ -12,7 +12,7 @@ resolution-markers = [
 ]

 [options]
-exclude-newer = "2024-08-08 00:00:00 UTC"
+exclude-newer = "2024-08-08T00:00:00Z"

 [[package]]
 name = "alabaster"
--- a/crates/uv/tests/snapshots/workflow__jax_instability-2.snap
+++ b/crates/uv/tests/snapshots/workflow__jax_instability-2.snap
@ -12,7 +12,7 @@ resolution-markers = [
 ]

 [options]
-exclude-newer = "2024-03-25 00:00:00 UTC"
+exclude-newer = "2024-03-25T00:00:00Z"

 [[package]]
 name = "importlib-metadata"
--- a/crates/uv/tests/snapshots/workflow__packse_add_remove_existing_package_noop-2.snap
+++ b/crates/uv/tests/snapshots/workflow__packse_add_remove_existing_package_noop-2.snap
@ -6,7 +6,7 @@ version = 1
 requires-python = ">=3.12"

 [options]
-exclude-newer = "2024-03-25 00:00:00 UTC"
+exclude-newer = "2024-03-25T00:00:00Z"

 [[package]]
 name = "anyio"
--- a/crates/uv/tests/snapshots/workflow__packse_add_remove_one_package-2.snap
+++ b/crates/uv/tests/snapshots/workflow__packse_add_remove_one_package-2.snap
@ -6,7 +6,7 @@ version = 1
 requires-python = ">=3.12"

 [options]
-exclude-newer = "2024-03-25 00:00:00 UTC"
+exclude-newer = "2024-03-25T00:00:00Z"

 [[package]]
 name = "anyio"
--- a/crates/uv/tests/snapshots/workflow__packse_promote_transitive_to_direct_then_remove-2.snap
+++ b/crates/uv/tests/snapshots/workflow__packse_promote_transitive_to_direct_then_remove-2.snap
@ -6,7 +6,7 @@ version = 1
 requires-python = ">=3.12"

 [options]
-exclude-newer = "2024-03-25 00:00:00 UTC"
+exclude-newer = "2024-03-25T00:00:00Z"

 [[package]]
 name = "anyio"
--- a/crates/uv/tests/sync.rs
+++ b/crates/uv/tests/sync.rs
@ -740,7 +740,7 @@ fn sync_relative_wheel() -> Result<()> {
            requires-python = ">=3.12"

            [options]
-            exclude-newer = "2024-03-25 00:00:00 UTC"
+            exclude-newer = "2024-03-25T00:00:00Z"

            [[package]]
            name = "ok"
--- a/crates/uv/tests/workflow.rs
+++ b/crates/uv/tests/workflow.rs
@ -429,7 +429,7 @@ fn jax_instability() -> Result<()> {
         ]

         [options]
-         exclude-newer = "2024-03-25 00:00:00 UTC"
+         exclude-newer = "2024-03-25T00:00:00Z"

         [[package]]
         name = "importlib-metadata"
@ -566,7 +566,7 @@ fn jax_instability() -> Result<()> {
         ]

         [options]
-         exclude-newer = "2024-03-25 00:00:00 UTC"
+         exclude-newer = "2024-03-25T00:00:00Z"

         [[package]]
         name = "importlib-metadata"
--- a/crates/uv/tests/workspace.rs
+++ b/crates/uv/tests/workspace.rs
@ -1086,7 +1086,7 @@ fn workspace_inherit_sources() -> Result<()> {
        requires-python = ">=3.12"

        [options]
-        exclude-newer = "2024-03-25 00:00:00 UTC"
+        exclude-newer = "2024-03-25T00:00:00Z"

        [manifest]
        members = [
--- a/docs/concepts/resolution.md
+++ b/docs/concepts/resolution.md
@ -263,7 +263,8 @@ unconditionally when using overrides — it does not matter if the marker evalua
 uv supports an `--exclude-newer` option to limit resolution to distributions published before a
 specific date, allowing reproduction of installations regardless of new package releases. The date
 may be specified as an [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamp (e.g.,
-`2006-12-02T02:07:43Z`) or UTC date in the same format (e.g., `2006-12-02`).
+`2006-12-02T02:07:43Z`) or a local date in the same format (e.g., `2006-12-02`) in your system's
+configured time zone.

 Note the package index must support the `upload-time` field as specified in
 [`PEP 700`](https://peps.python.org/pep-0700/). If the field is not present for a given
--- a/docs/reference/cli.md
+++ b/docs/reference/cli.md
@ -100,7 +100,7 @@ uv run [OPTIONS] <COMMAND>

 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra</code> <i>extra</i></dt><dd><p>Include optional dependencies from the extra group name.</p>

@ -513,7 +513,7 @@ uv add [OPTIONS] <PACKAGES|--requirements <REQUIREMENTS>>

 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra</code> <i>extra</i></dt><dd><p>Extras to enable for the dependency.</p>

@ -797,7 +797,7 @@ uv remove [OPTIONS] <PACKAGES>...

 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra-index-url</code> <i>extra-index-url</i></dt><dd><p>Extra URLs of package indexes to use, in addition to <code>--index-url</code>.</p>

@ -1049,7 +1049,7 @@ uv sync [OPTIONS]

 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra</code> <i>extra</i></dt><dd><p>Include optional dependencies from the extra group name.</p>

@ -1299,7 +1299,7 @@ uv lock [OPTIONS]

 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra-index-url</code> <i>extra-index-url</i></dt><dd><p>Extra URLs of package indexes to use, in addition to <code>--index-url</code>.</p>

@ -1526,7 +1526,7 @@ uv tree [OPTIONS]
 <p>[default: 255]</p>
 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra-index-url</code> <i>extra-index-url</i></dt><dd><p>Extra URLs of package indexes to use, in addition to <code>--index-url</code>.</p>

@ -1855,7 +1855,7 @@ uv tool run [OPTIONS] [COMMAND]

 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra-index-url</code> <i>extra-index-url</i></dt><dd><p>Extra URLs of package indexes to use, in addition to <code>--index-url</code>.</p>

@ -2097,7 +2097,7 @@ uv tool install [OPTIONS] <PACKAGE>

 </dd><dt><code>--editable</code>, <code>-e</code></dt><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra-index-url</code> <i>extra-index-url</i></dt><dd><p>Extra URLs of package indexes to use, in addition to <code>--index-url</code>.</p>

@ -2339,7 +2339,7 @@ uv tool upgrade [OPTIONS] <NAME>

 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra-index-url</code> <i>extra-index-url</i></dt><dd><p>Extra URLs of package indexes to use, in addition to <code>--index-url</code>.</p>

@ -3625,7 +3625,7 @@ uv pip compile [OPTIONS] <SRC_FILE>...

 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra</code> <i>extra</i></dt><dd><p>Include optional dependencies from the extra group name; may be provided more than once.</p>

@ -3974,7 +3974,7 @@ uv pip sync [OPTIONS] <SRC_FILE>...

 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra-index-url</code> <i>extra-index-url</i></dt><dd><p>Extra URLs of package indexes to use, in addition to <code>--index-url</code>.</p>

@ -4269,7 +4269,7 @@ uv pip install [OPTIONS] <PACKAGE|--requirement <REQUIREMENT>|--editable <EDITAB

 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra</code> <i>extra</i></dt><dd><p>Include optional dependencies from the extra group name; may be provided more than once.</p>

@ -5238,7 +5238,7 @@ uv venv [OPTIONS] [NAME]

 </dd><dt><code>--exclude-newer</code> <i>exclude-newer</i></dt><dd><p>Limit candidate packages to those that were uploaded prior to the given date.</p>

-<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and UTC dates in the same format (e.g., <code>2006-12-02</code>).</p>
+<p>Accepts both RFC 3339 timestamps (e.g., <code>2006-12-02T02:07:43Z</code>) and local dates in the same format (e.g., <code>2006-12-02</code>) in your system&#8217;s configured time zone.</p>

 </dd><dt><code>--extra-index-url</code> <i>extra-index-url</i></dt><dd><p>Extra URLs of package indexes to use, in addition to <code>--index-url</code>.</p>

--- a/docs/reference/settings.md
+++ b/docs/reference/settings.md
@ -149,7 +149,8 @@ unsatisfiable branches in the solution space.
 Limit candidate packages to those that were uploaded prior to the given date.

 Accepts both [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamps (e.g.,
-`2006-12-02T02:07:43Z`) and UTC dates in the same format (e.g., `2006-12-02`).
+`2006-12-02T02:07:43Z`) and local dates in the same format (e.g., `2006-12-02`) in your
+system's configured time zone.

 **Default value**: `None`

@ -1385,7 +1386,8 @@ be correct.
 Limit candidate packages to those that were uploaded prior to the given date.

 Accepts both [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamps (e.g.,
-`2006-12-02T02:07:43Z`) and UTC dates in the same format (e.g., `2006-12-02`).
+`2006-12-02T02:07:43Z`) and local dates in the same format (e.g., `2006-12-02`) in your
+system's configured time zone.

 **Default value**: `None`

--- a/uv.schema.json
+++ b/uv.schema.json
@ -59,7 +59,7 @@
      }
    },
    "exclude-newer": {
-      "description": "Limit candidate packages to those that were uploaded prior to the given date.\n\nAccepts both [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamps (e.g., `2006-12-02T02:07:43Z`) and UTC dates in the same format (e.g., `2006-12-02`).",
+      "description": "Limit candidate packages to those that were uploaded prior to the given date.\n\nAccepts both [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamps (e.g., `2006-12-02T02:07:43Z`) and local dates in the same format (e.g., `2006-12-02`) in your system's configured time zone.",
      "anyOf": [
        {
          "$ref": "#/definitions/ExcludeNewer"
@ -414,7 +414,7 @@
      }
    },
    "ExcludeNewer": {
-      "description": "Exclude distributions uploaded after the given timestamp.\n\nAccepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and UTC dates in the same format (e.g., `2006-12-02`).",
+      "description": "Exclude distributions uploaded after the given timestamp.\n\nAccepts both RFC 3339 timestamps (e.g., `2006-12-02T02:07:43Z`) and local dates in the same format (e.g., `2006-12-02`).",
      "type": "string",
      "pattern": "^\\d{4}-\\d{2}-\\d{2}(T\\d{2}:\\d{2}:\\d{2}(Z|[+-]\\d{2}:\\d{2}))?$"
    },
@ -641,7 +641,7 @@
          ]
        },
        "exclude-newer": {
-          "description": "Limit candidate packages to those that were uploaded prior to the given date.\n\nAccepts both [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamps (e.g., `2006-12-02T02:07:43Z`) and UTC dates in the same format (e.g., `2006-12-02`).",
+          "description": "Limit candidate packages to those that were uploaded prior to the given date.\n\nAccepts both [RFC 3339](https://www.rfc-editor.org/rfc/rfc3339.html) timestamps (e.g., `2006-12-02T02:07:43Z`) and local dates in the same format (e.g., `2006-12-02`) in your system's configured time zone.",
          "anyOf": [
            {
              "$ref": "#/definitions/ExcludeNewer"