fix(desktop): retry transient rcedit commit failures

Windows desktop rebuilds intermittently hit rcedit's `Fatal error: Unable
to commit changes` while a real-time file scanner holds the freshly packed
Hermes.exe; `stampExeIdentity` called rcedit exactly once, so the stamp
failed on the first lock. Retry the commit with bounded backoff before
surfacing the original error.

Trimmed from #112552: the after-pack.mjs injection seam and its test —
the hook's swallow-and-warn is pre-existing behaviour on main and needs no
change (the reporter's "Could not install the rebuilt desktop app" comes
from hermes_cli/main_desktop.py::_swap_staged_desktop_app's directory
rename, not from the stamp).

apps/desktop/scripts/set-exe-identity.mjs

@@ -42,10 +42,20 @@ import { rcedit } from 'rcedit'
 
 import { isMain } from './utils.mjs'
 
+const RCEDIT_COMMIT_RETRY_DELAYS_MS = [100, 300]
+
+function wait(delay) {
+  return new Promise(resolve => setTimeout(resolve, delay))
+}
+
 // Stamp the Hermes icon + identity onto `exe`. Resolves on success, throws on
 // failure. `desktopRoot` defaults to this script's package root so the icon and
 // the rcedit dependency resolve regardless of cwd.
-async function stampExeIdentity(exe, desktopRoot = resolve(import.meta.dirname, '..')) {
+async function stampExeIdentity(
+  exe,
+  desktopRoot = resolve(import.meta.dirname, '..'),
+  { rcedit: runRcedit = rcedit, sleep = wait } = {}
+) {
   if (!exe || !existsSync(exe)) {
     throw new Error(`target exe not found: ${exe}`)
   }
@@ -59,7 +69,7 @@ async function stampExeIdentity(exe, desktopRoot = resolve(import.meta.dirname,
   console.log(`[set-exe-identity] stamping ${exe}`)
   console.log(`[set-exe-identity] icon: ${icon}`)
 
-  await rcedit(exe, {
+  const options = {
     icon,
     'version-string': {
       ProductName: 'Hermes',
@@ -67,12 +77,26 @@ async function stampExeIdentity(exe, desktopRoot = resolve(import.meta.dirname,
       CompanyName: 'Nous Research',
       LegalCopyright: 'Copyright (c) 2026 Nous Research'
     }
-  })
+  }
+
+  for (let attempt = 0; ; attempt += 1) {
+    try {
+      await runRcedit(exe, options)
+      break
+    } catch (err) {
+      const delay = RCEDIT_COMMIT_RETRY_DELAYS_MS[attempt]
+      if (!/unable to commit changes/i.test(err?.message) || delay === undefined) {
+        throw err
+      }
+      console.warn(`[set-exe-identity] rcedit commit failed; retrying in ${delay}ms (${err.message})`)
+      await sleep(delay)
+    }
+  }
 
   console.log('[set-exe-identity] done — Hermes icon + identity stamped')
 }
 
-export { stampExeIdentity }
+export { RCEDIT_COMMIT_RETRY_DELAYS_MS, stampExeIdentity }
 
 // CLI entry point: `node scripts/set-exe-identity.mjs <exe>`.
 if (isMain(import.meta.url)) {

apps/desktop/scripts/set-exe-identity.test.mjs

@@ -0,0 +1,58 @@
+import assert from 'node:assert/strict'
+import fs from 'node:fs'
+import os from 'node:os'
+import path from 'node:path'
+import { test } from 'vitest'
+
+import { stampExeIdentity } from './set-exe-identity.mjs'
+
+function makeDesktopRoot() {
+  const root = fs.mkdtempSync(path.join(os.tmpdir(), 'hermes-exe-identity-'))
+  fs.mkdirSync(path.join(root, 'assets'))
+  fs.writeFileSync(path.join(root, 'assets', 'icon.ico'), 'icon')
+  const exe = path.join(root, 'Hermes.exe')
+  fs.writeFileSync(exe, 'exe')
+  return { exe, root }
+}
+
+test('retries transient rcedit commit failures with bounded backoff', async () => {
+  const { exe, root } = makeDesktopRoot()
+  const delays = []
+  let attempts = 0
+
+  try {
+    await stampExeIdentity(exe, root, {
+      rcedit: async () => {
+        attempts += 1
+        if (attempts < 3) throw new Error('Unable to commit changes')
+      },
+      sleep: async delay => delays.push(delay)
+    })
+
+    assert.equal(attempts, 3)
+    assert.deepEqual(delays, [100, 300])
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true })
+  }
+})
+
+test('stops retrying after the bounded rcedit retry budget is exhausted', async () => {
+  const { exe, root } = makeDesktopRoot()
+  let attempts = 0
+
+  try {
+    await assert.rejects(
+      stampExeIdentity(exe, root, {
+        rcedit: async () => {
+          attempts += 1
+          throw new Error('Unable to commit changes')
+        },
+        sleep: async () => {}
+      }),
+      /Unable to commit changes/
+    )
+    assert.equal(attempts, 3)
+  } finally {
+    fs.rmSync(root, { recursive: true, force: true })
+  }
+})