Greptile Summary

This PR correctly fixes issue #37309 by inverting the precedence in merge mode so that config values take priority when non-empty.

The fix:

• mergeWithExistingProviderSecrets now checks whether the incoming config provides non-empty apiKey/baseUrl before deciding whether to preserve the agent state value
• Config values win when explicitly set to non-empty strings, enabling config changes to take effect on restart
• Agent values are only preserved when config omits the field or provides an empty string, maintaining backward compatibility

Testing:

• Renamed test now validates config-wins behavior (fixes [Bug]: Cannot update vLLM base URL; agent caches old config in hidden models.json #37309)
• New test explicitly validates backward compatibility when config provides empty strings
• Existing test validates agent values take effect when config is empty
• All 71 tests pass

Documentation:

• Help text updated to clearly explain the new merge behavior and the precedence rules

The change is minimal, surgical, and safe to merge.

Confidence Score: 5/5

• This PR is safe to merge; it's a targeted behavioral fix with no risk of regressions to unrelated code paths.
• The change is minimal and surgical — two additional boolean guards in a single private function. Both the bug-fix case (config wins) and the backward-compatibility case (agent preserved when config empty) are covered by explicit tests. The logic cleanly captures "config provides a non-empty value" and the merge mode behavior is properly documented. All 71 tests pass.
• No files require special attention.

_{Last reviewed commit: 25bbfcc}

@gumadeiras can help me review this pr,thanks

Closing this PR because the author has more than 10 active PRs in this repo. Please reduce the active PR queue and reopen or resubmit once it is back under the limit. You can close your own PRs to get back under the limit.