From 49bb084a4c166c1b565f8ab4951596426f0fda9b Mon Sep 17 00:00:00 2001
From: Pete Hayes <pete@hayes.id.au>
Date: Fri, 12 Jun 2026 11:24:35 +1000
Subject: [PATCH 1/2] Add From<Duration> conversion for Instant

---
 src/time/instant.rs | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/time/instant.rs b/src/time/instant.rs
index 0c041d4..10d08ba 100644
--- a/src/time/instant.rs
+++ b/src/time/instant.rs
@@ -123,6 +123,12 @@ impl Instant {
 	}
 }
 
+impl From<Duration> for Instant {
+	fn from(duration: Duration) -> Self {
+		Self(duration)
+	}
+}
+
 impl Add<Duration> for Instant {
 	type Output = Self;
 

From a9f56e9d3346d76361f7462fc67b059de3313671 Mon Sep 17 00:00:00 2001
From: Pete Hayes <pete@hayes.id.au>
Date: Wed, 8 Jul 2026 11:40:32 +1000
Subject: [PATCH 2/2] Move patch to web.rs

---
 src/time/instant.rs |  8 +-------
 src/web.rs          | 44 +++++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 44 insertions(+), 8 deletions(-)

diff --git a/src/time/instant.rs b/src/time/instant.rs
index 10d08ba..08a07e6 100644
--- a/src/time/instant.rs
+++ b/src/time/instant.rs
@@ -21,7 +21,7 @@ use super::js::TIME_ORIGIN;
 	doc = "[`std::time::Instant`]: https://doc.rust-lang.org/std/time/struct.Instant.html"
 )]
 #[derive(Clone, Copy, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
-pub struct Instant(Duration);
+pub struct Instant(pub(crate) Duration);
 
 impl Instant {
 	/// See [`std::time::Instant::now()`].
@@ -123,12 +123,6 @@ impl Instant {
 	}
 }
 
-impl From<Duration> for Instant {
-	fn from(duration: Duration) -> Self {
-		Self(duration)
-	}
-}
-
 impl Add<Duration> for Instant {
 	type Output = Self;
 
diff --git a/src/web.rs b/src/web.rs
index d79d6a0..ce419f0 100644
--- a/src/web.rs
+++ b/src/web.rs
@@ -2,9 +2,10 @@
 
 #![allow(clippy::absolute_paths)]
 
+use core::time::Duration;
 use std::time::SystemTime as StdSystemTime;
 
-use crate::SystemTime;
+use crate::{Instant, SystemTime};
 
 #[cfg(all(
 	target_arch = "wasm32",
@@ -79,3 +80,44 @@ impl SystemTimeExt for SystemTime {
 				.expect("found `SystemTime` earlier than unix epoch")
 	}
 }
+
+/// Web-specific extension to [`web_time::Instant`](crate::Instant).
+pub trait InstantExt {
+	/// Create a [`web_time::Instant`](crate::Instant) from a [`Duration`]
+	/// representing the monotonic time elapsed since an arbitrary, fixed
+	/// origin.
+	///
+	/// # Note
+	///
+	/// The resulting [`Instant`](crate::Instant) is only meaningful relative to
+	/// other [`Instant`](crate::Instant)s that share the same origin (whether
+	/// obtained via [`Instant::now()`](crate::Instant::now) or this method).
+	/// Mixing timestamps from different origins will yield nonsensical
+	/// [`Duration`]s.
+	///
+	/// [`Performance.now()`]: https://developer.mozilla.org/en-US/docs/Web/API/Performance/now
+	/// [`Performance.timeOrigin`]: https://developer.mozilla.org/en-US/docs/Web/API/Performance/timeOrigin
+	#[must_use]
+	fn from_duration(duration: Duration) -> Self;
+
+	/// Returns the [`Duration`] backing this [`Instant`](crate::Instant), i.e.
+	/// the monotonic time elapsed since the origin it was created from.
+	///
+	/// # Note
+	///
+	/// Like [`InstantExt::from_duration`], the returned [`Duration`] is only
+	/// meaningful relative to other [`Instant`](crate::Instant)s sharing the
+	/// same origin.
+	#[must_use]
+	fn as_duration(&self) -> Duration;
+}
+
+impl InstantExt for Instant {
+	fn from_duration(duration: Duration) -> Self {
+		Self(duration)
+	}
+
+	fn as_duration(&self) -> Duration {
+		self.0
+	}
+}