[Bug] Agent reports failed patch job (context canceled) during Windows postPatchReboot despite successful installation

We are managing a fleet of Windows Server instances across roughly 17 different GCP projects. Starting around the April 2026 patching cycle, we've started seeing random "false negative" failures across various instances.

`Error running postPatchReboot: error reporting state REBOOTING: error calling ReportTaskProgress: code: "Canceled", message: "context canceled", details: []`

The Windows cumulative updates are installing successfully, but the OS Config patch job reports as failed. It looks like a race condition during the reboot phase: the agent attempts to report the REBOOTING state via ReportTaskProgress, but the Windows restart sequence tears down the network stack before the gRPC call can complete.

The issue identifies the Windows postPatchReboot flow and its ReportTaskProgress call; start by tracing that reboot-state reporting path and reproducing cancellation during restart. Done means a successfully installed update is not reported as a failed patch job when the network disappears during reboot; no specific file or test is named.

Written by the indexing model from the issue text.