/claim #7724

Summary

Re-submit of the stale SSH key synchronization fix for intermittent Permission denied (publickey,password) failures.

This patch makes validateSshKey() actively repair missing/stale key files before command execution by comparing key fingerprints (DB vs disk), then resets the current server mux file if a re-sync occurs.

Why this is targeted

• Existing logic only ensured key file existence.
• Sporadic auth failures are consistent with stale/corrupted per-node key material and stale mux sessions.
• Fingerprint comparison avoids brittle raw-content assumptions and keeps blast radius local to the active server context.

Changes

• app/Helpers/SshMultiplexingHelper.php
  • validateSshKey(PrivateKey $privateKey, ?Server $server = null)
  • detect stale/missing key file using fingerprint mismatch
  • re-store DB key material to disk when mismatch found
  • invalidate current server mux file when sync happens
• tests/Unit/SshKeyFileSyncTest.php
  • missing key file is recreated
  • corrupted key file is repaired

Verification

• Unit test coverage added for both missing-file and corrupted-file repair paths.
• Local CI-style PHP test execution is environment-constrained in this workspace, but patch is scoped, deterministic, and covered by focused unit tests for maintainer CI.