From 0fcd327795aed0195b1061dc4c50ee3c18b6cfd6 Mon Sep 17 00:00:00 2001
From: Pybsama <294532706+Pybsama@users.noreply.github.com>
Date: Wed, 29 Jul 2026 13:02:08 +0800
Subject: [PATCH 1/2] fix: honor year precision for elapsed durations

---
 src/duration.ts       |  3 ++-
 test/duration.ts      | 12 ++++++++++++
 test/relative-time.js | 12 ++++++++++++
 3 files changed, 26 insertions(+), 1 deletion(-)

diff --git a/src/duration.ts b/src/duration.ts
index eb41a53c..2329918c 100644
--- a/src/duration.ts
+++ b/src/duration.ts
@@ -156,7 +156,8 @@ export function elapsedTime(date: Date, precision: Unit = 'second', now = Date.n
   const day = Math.floor(hr / 24)
   const month = Math.floor(day / 30)
   const year = Math.floor(month / 12)
-  const i = unitNames.indexOf(precision) || unitNames.length
+  const precisionIndex = unitNames.indexOf(precision)
+  const i = precisionIndex === -1 ? unitNames.length : precisionIndex
   return new Duration(
     i >= 0 ? year * sign : 0,
     i >= 1 ? (month - year * 12) * sign : 0,
diff --git a/test/duration.ts b/test/duration.ts
index 95968531..8fab295f 100644
--- a/test/duration.ts
+++ b/test/duration.ts
@@ -224,6 +224,18 @@ suite('duration', function () {
         input: '2023-03-21T16:03:00.000Z',
         expected: '-P1DT20H',
       },
+      {
+        now: '2022-10-24T14:46:00.000Z',
+        input: '2024-10-24T14:46:00.000Z',
+        precision: 'year',
+        expected: 'P2Y',
+      },
+      {
+        now: '2022-10-24T14:46:00.000Z',
+        input: '2020-10-24T14:46:00.000Z',
+        precision: 'year',
+        expected: '-P2Y',
+      },
     ])
     for (const {input, now, precision = 'millisecond', expected} of elapsed) {
       test(`${input} is ${expected} elapsed from ${now} (precision ${precision})`, () => {
diff --git a/test/relative-time.js b/test/relative-time.js
index 307ba594..59b658b4 100644
--- a/test/relative-time.js
+++ b/test/relative-time.js
@@ -1561,6 +1561,12 @@ suite('relative-time', function () {
         format: 'duration',
         expected: '2 years, 11 days',
       },
+      {
+        datetime: '2024-10-24T14:46:00.000Z',
+        format: 'duration',
+        precision: 'year',
+        expected: '2 years',
+      },
       {
         datetime: '2024-10-24T14:46:00.000Z',
         format: 'duration',
@@ -2680,6 +2686,12 @@ suite('relative-time', function () {
         format: 'elapsed',
         expected: '1y',
       },
+      {
+        datetime: '2020-10-24T14:46:00.000Z',
+        format: 'elapsed',
+        precision: 'year',
+        expected: '2y',
+      },
 
       // Dates in the past
       {

From 0a350cb171a688932186d84be3a1741666899ad2 Mon Sep 17 00:00:00 2001
From: Pybsama <294532706+Pybsama@users.noreply.github.com>
Date: Wed, 29 Jul 2026 13:07:47 +0800
Subject: [PATCH 2/2] fix: preserve unknown precision behavior

---
 src/duration.ts  | 3 +--
 test/duration.ts | 7 +++++++
 2 files changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/duration.ts b/src/duration.ts
index 2329918c..0195fc20 100644
--- a/src/duration.ts
+++ b/src/duration.ts
@@ -156,8 +156,7 @@ export function elapsedTime(date: Date, precision: Unit = 'second', now = Date.n
   const day = Math.floor(hr / 24)
   const month = Math.floor(day / 30)
   const year = Math.floor(month / 12)
-  const precisionIndex = unitNames.indexOf(precision)
-  const i = precisionIndex === -1 ? unitNames.length : precisionIndex
+  const i = unitNames.indexOf(precision)
   return new Duration(
     i >= 0 ? year * sign : 0,
     i >= 1 ? (month - year * 12) * sign : 0,
diff --git a/test/duration.ts b/test/duration.ts
index 8fab295f..87707de1 100644
--- a/test/duration.ts
+++ b/test/duration.ts
@@ -1,5 +1,6 @@
 import {assert} from '@open-wc/testing'
 import {applyDuration, Duration, elapsedTime, getRelativeTimeUnit, roundToSingleUnit} from '../src/duration.ts'
+import type {Unit} from '../src/duration.ts'
 import type {DurationFormatOptions} from '../src/duration-format-ponyfill.ts'
 import {Temporal} from '@js-temporal/polyfill'
 
@@ -236,6 +237,12 @@ suite('duration', function () {
         precision: 'year',
         expected: '-P2Y',
       },
+      {
+        now: '2022-10-24T14:46:00.000Z',
+        input: '2024-10-24T14:46:00.000Z',
+        precision: 'unknown' as Unit,
+        expected: 'PT0S',
+      },
     ])
     for (const {input, now, precision = 'millisecond', expected} of elapsed) {
       test(`${input} is ${expected} elapsed from ${now} (precision ${precision})`, () => {