fix(update): resume deferred Windows desktop updates

scripts/desktop-update/retry-policy.ps1

@@ -0,0 +1,15 @@
+function Test-HermesUpdateShouldRetry {
+    param(
+        [int]$ExitCode,
+        [string]$InstallRoot
+    )
+
+    if ($ExitCode -eq 0) { return $false }
+    if ($ExitCode -ne 2) { return $true }
+
+    # Exit 2 is shared by non-retryable safety refusals and the self-lock
+    # deferral. Only the latter writes this marker, which a fresh Python
+    # process consumes before importing native modules.
+    $deferredInstallMarker = Join-Path $InstallRoot ".update-incomplete"
+    return Test-Path -LiteralPath $deferredInstallMarker
+}

scripts/desktop-update/windows.ps1

@@ -1498,10 +1498,13 @@ try {
     $res = Invoke-HermesStep $pythonExe $updateArgs "update"
     Write-HandoffLog "hermes update exit code: $($res.Code)"
 
-    if ($res.Code -ne 0 -and $res.Code -ne 2) {
-        # One retry for the update-boundary class (fresh code on disk, stale
-        # code in memory). Exit 2 ("close all Hermes windows") is not retryable.
-        Write-HandoffLog "first attempt failed; retrying once (freshly pulled fix loads on the second run)"
+    . (Join-Path $PSScriptRoot "retry-policy.ps1")
+    if (Test-HermesUpdateShouldRetry -ExitCode $res.Code -InstallRoot $InstallRoot) {
+        # One retry for update-boundary failures. Most exit-2 safety refusals
+        # remain terminal, but self-lock deferral also uses exit 2 and writes
+        # .update-incomplete after the code swap. A fresh process consumes that
+        # marker before native imports, then resumes the full update pipeline.
+        Write-HandoffLog "first attempt left retryable update state; retrying once in a fresh process"
         Publish-UiProgress "Retrying update"
         $res = Invoke-HermesStep $pythonExe $updateArgs "update"
         Write-HandoffLog "retry exit code: $($res.Code)"

tests/test_desktop_update_windows_retry_policy.py

@@ -0,0 +1,56 @@
+"""Windows Desktop handoff retry policy behavior."""
+
+from __future__ import annotations
+
+import json
+import subprocess
+from pathlib import Path
+
+import pytest
+
+
+REPO_ROOT = Path(__file__).resolve().parent.parent
+RETRY_POLICY = REPO_ROOT / "scripts" / "desktop-update" / "retry-policy.ps1"
+
+
+@pytest.mark.windows_only
+def test_retry_policy_distinguishes_self_lock_deferral(tmp_path: Path) -> None:
+    install_root = tmp_path / "hermes-agent"
+    install_root.mkdir()
+    marker = install_root / ".update-incomplete"
+
+    policy = str(RETRY_POLICY).replace("'", "''")
+    root = str(install_root).replace("'", "''")
+    command = f"""
+        . '{policy}'
+        $withoutMarker = @(
+            (Test-HermesUpdateShouldRetry -ExitCode 0 -InstallRoot '{root}'),
+            (Test-HermesUpdateShouldRetry -ExitCode 1 -InstallRoot '{root}'),
+            (Test-HermesUpdateShouldRetry -ExitCode 2 -InstallRoot '{root}')
+        )
+        New-Item -ItemType File -Path (Join-Path '{root}' '.update-incomplete') | Out-Null
+        $withMarker = Test-HermesUpdateShouldRetry -ExitCode 2 -InstallRoot '{root}'
+        @{{ withoutMarker = $withoutMarker; withMarker = $withMarker }} |
+            ConvertTo-Json -Compress
+    """
+    result = subprocess.run(
+        [
+            "powershell",
+            "-NoProfile",
+            "-ExecutionPolicy",
+            "Bypass",
+            "-Command",
+            command,
+        ],
+        check=False,
+        capture_output=True,
+        text=True,
+        timeout=30,
+    )
+
+    assert result.returncode == 0, result.stdout + result.stderr
+    assert json.loads(result.stdout) == {
+        "withoutMarker": [False, True, False],
+        "withMarker": True,
+    }
+    assert marker.exists()