Copilot chat saving only saves the initial prompt.

[t-rad679]

• Disable all other plugins besides Copilot (required)
• Log file generated via "Copilot: Create Log File" command or Settings -> Advanced -> Create Log File (required)
• Screenshot of note + Copilot chat pane + dev console added (optional)

Copilot version: 3.1.3
Model used: gemini-2.5-pro
OS: Arch Linux

(Bug reports missing the required items above will be closed)

Description of Failure
The only content that is ever saved to my Copilot chat conversation notes is the initial prompt. No later user input or AI responses are saved to the note. A toast pops up saying that there was an error saving the note and to check the Dev Console, but no error shows up in the Dev Console unless debug mode is enabled. The error message is "file already exists" so it seems that the problem is Copilot trying to create the note file instead of appending to it.

Describe how to reproduce

1. On Linux, start a new Copilot chat with the setting enabled to automatically save chats to the vault.
2. After the AI responds, notice that the note only contains the initial prompt and that the toast pops up. If you have debug mode enabled, you can also check the dev console for the error message.

Expected behavior
The chat content should always be saved to the conversation note.

Screenshots
Add screenshots to help explain your problem. Please turn on debug mode in Copilot settings, turn off other plugins to leave only Copilot dev messages as necessary.

Additional context
copilot.log

Note this does not happen on MacOS, so it has something to do with which system calls are being made on Linux specifically.