fix(update): compare prerelease identifiers numerically, not lexicogr…

scripts/build-version-index.mjs

@@ -3,6 +3,36 @@ import { fileURLToPath } from 'node:url'
 
 const SEMVER = /^\d+\.\d+\.\d+(?:[-+][0-9A-Za-z.-]+)?$/
 
+function comparePrerelease(a, b) {
+  if (a === b) return 0
+  if (!a) return 1
+  if (!b) return -1
+  const la = a.split('.')
+  const lb = b.split('.')
+  const length = Math.max(la.length, lb.length)
+  for (let i = 0; i < length; i += 1) {
+    const x = la[i]
+    const y = lb[i]
+    if (x === undefined) return -1
+    if (y === undefined) return 1
+    if (x === y) continue
+    const xn = /^\d+$/.test(x)
+    const yn = /^\d+$/.test(y)
+    if (xn && yn) {
+      const nx = x.replace(/^0+/, '') || '0'
+      const ny = y.replace(/^0+/, '') || '0'
+      if (nx.length !== ny.length) return nx.length < ny.length ? -1 : 1
+      if (nx !== ny) return nx < ny ? -1 : 1
+      continue
+    }
+    if (xn) return -1
+    if (yn) return 1
+    if (x < y) return -1
+    if (x > y) return 1
+  }
+  return 0
+}
+
 function compare(a, b) {
   const pa = a.split('-')[0].split('.').map(Number)
   const pb = b.split('-')[0].split('.').map(Number)
@@ -11,10 +41,7 @@ function compare(a, b) {
   }
   const preA = a.includes('-') ? a.slice(a.indexOf('-') + 1) : ''
   const preB = b.includes('-') ? b.slice(b.indexOf('-') + 1) : ''
-  if (preA === preB) return 0
-  if (!preA) return 1
-  if (!preB) return -1
-  return preA < preB ? -1 : 1
+  return comparePrerelease(preA, preB)
 }
 
 /**

src/main/update/version-catalog.ts

@@ -29,10 +29,48 @@ export function compareVersions(a: string, b: string): -1 | 0 | 1 {
     const diff = (left.nums[i] ?? 0) - (right.nums[i] ?? 0)
     if (diff !== 0) return diff < 0 ? -1 : 1
   }
-  if (left.pre === right.pre) return 0
-  if (!left.pre) return 1 // release > prerelease
-  if (!right.pre) return -1
-  return left.pre < right.pre ? -1 : 1
+  return comparePrerelease(left.pre, right.pre)
+}
+
+/**
+ * Semver-style prerelease precedence once the numeric core is equal. A release
+ * (no prerelease) sorts above any prerelease; dot-separated identifiers
+ * compare with numeric identifiers numerically and below alphanumeric ones,
+ * and fewer identifiers sort below more ("alpha" < "alpha.1"). Plain string
+ * comparison would order "rc.10" below "rc.9", mis-sorting the archive index
+ * (and the picker/downgrade split in the preload) once a prerelease counter
+ * reaches two digits.
+ */
+function comparePrerelease(left: string, right: string): -1 | 0 | 1 {
+  if (left === right) return 0
+  if (!left) return 1 // release > prerelease
+  if (!right) return -1
+  const l = left.split('.')
+  const r = right.split('.')
+  const length = Math.max(l.length, r.length)
+  for (let i = 0; i < length; i += 1) {
+    const x = l[i]
+    const y = r[i]
+    if (x === undefined) return -1 // fewer identifiers sorts below
+    if (y === undefined) return 1
+    if (x === y) continue
+    const xn = /^\d+$/.test(x)
+    const yn = /^\d+$/.test(y)
+    if (xn && yn) {
+      // Compare without Number() so leading-zero forms and large counters do
+      // not lose precision.
+      const nx = x.replace(/^0+/, '') || '0'
+      const ny = y.replace(/^0+/, '') || '0'
+      if (nx.length !== ny.length) return nx.length < ny.length ? -1 : 1
+      if (nx !== ny) return nx < ny ? -1 : 1
+      continue
+    }
+    if (xn) return -1 // numeric identifiers sort below alphanumeric ones
+    if (yn) return 1
+    if (x < y) return -1
+    if (x > y) return 1
+  }
+  return 0
 }
 
 function isRelease(value: unknown): value is AvailableRelease {

src/preload/index.ts

@@ -544,7 +544,9 @@ function skipButton(status: UpdateStatus): HTMLButtonElement {
 
 /** Compare two dotted versions; prerelease sorts below its release. Mirrors
  * `version-catalog.compareVersions` — a small duplication across the
- * main/preload boundary, kept local so the preload bundle stays standalone. */
+ * main/preload boundary, kept local so the preload bundle stays standalone.
+ * Keep the two implementations in lockstep, including the semver-style
+ * numeric prerelease comparison below ("rc.10" > "rc.9"). */
 function comparePreloadVersions(a: string, b: string): number {
   const parse = (value: string): [number[], string] => {
     const [core = '', ...pre] = value.trim().split('-')
@@ -557,10 +559,37 @@ function comparePreloadVersions(a: string, b: string): number {
   for (let i = 0; i < 3; i += 1) {
     if ((an[i] ?? 0) !== (bn[i] ?? 0)) return (an[i] ?? 0) - (bn[i] ?? 0)
   }
-  if (ap === bp) return 0
-  if (!ap) return 1
-  if (!bp) return -1
-  return ap < bp ? -1 : 1
+  return comparePrerelease(ap, bp)
+}
+
+function comparePrerelease(left: string, right: string): number {
+  if (left === right) return 0
+  if (!left) return 1
+  if (!right) return -1
+  const l = left.split('.')
+  const r = right.split('.')
+  const length = Math.max(l.length, r.length)
+  for (let i = 0; i < length; i += 1) {
+    const x = l[i]
+    const y = r[i]
+    if (x === undefined) return -1
+    if (y === undefined) return 1
+    if (x === y) continue
+    const xn = /^\d+$/.test(x)
+    const yn = /^\d+$/.test(y)
+    if (xn && yn) {
+      const nx = x.replace(/^0+/, '') || '0'
+      const ny = y.replace(/^0+/, '') || '0'
+      if (nx.length !== ny.length) return nx.length < ny.length ? -1 : 1
+      if (nx !== ny) return nx < ny ? -1 : 1
+      continue
+    }
+    if (xn) return -1
+    if (yn) return 1
+    if (x < y) return -1
+    if (x > y) return 1
+  }
+  return 0
 }
 
 function loadVersionList(onDone?: () => void): void {

test/build-version-index.test.ts

@@ -24,6 +24,21 @@ describe('buildVersionIndex', () => {
     ])
   })
 
+  it('orders prerelease counters numerically so rc.10 is newer than rc.9', () => {
+    const index = buildVersionIndex([
+      '1.2.3-rc.1',
+      '1.2.3-rc.10',
+      '1.2.3-rc.9',
+      '1.2.3-rc.2'
+    ])
+    expect(index.versions.map((v: { version: string }) => v.version)).toEqual([
+      '1.2.3-rc.10',
+      '1.2.3-rc.9',
+      '1.2.3-rc.2',
+      '1.2.3-rc.1'
+    ])
+  })
+
   it('derives tag and archiveUrl for each entry', () => {
     const [entry] = buildVersionIndex(['3.4.5']).versions
     expect(entry).toEqual({

test/version-catalog.test.ts

@@ -31,6 +31,23 @@ describe('compareVersions', () => {
     expect(compareVersions('1.2.3', '1.2.3-rc.1')).toBe(1)
     expect(compareVersions('1.2.3-rc.1', '1.2.3-rc.2')).toBe(-1)
   })
+
+  it('compares prerelease counters numerically, not lexicographically', () => {
+    // "rc.10" < "rc.9" under string comparison; semver says the reverse.
+    expect(compareVersions('1.2.3-rc.10', '1.2.3-rc.9')).toBe(1)
+    expect(compareVersions('1.2.3-rc.9', '1.2.3-rc.10')).toBe(-1)
+    expect(compareVersions('1.2.3-alpha.10', '1.2.3-alpha.9')).toBe(1)
+    expect(compareVersions('1.2.3-rc.10', '1.2.3-rc.1')).toBe(1)
+  })
+
+  it('follows semver identifier precedence', () => {
+    // fewer identifiers < more ("alpha" < "alpha.1")
+    expect(compareVersions('1.2.3-alpha', '1.2.3-alpha.1')).toBe(-1)
+    // numeric identifiers < alphanumeric ones ("1" < "alpha")
+    expect(compareVersions('1.2.3-1', '1.2.3-alpha')).toBe(-1)
+    expect(compareVersions('1.2.3-alpha', '1.2.3-beta')).toBe(-1)
+    expect(compareVersions('1.2.3-rc.10', '1.2.3-rc.10')).toBe(0)
+  })
 })
 
 describe('parseVersionIndex', () => {