Agent's follow up changes reverts the previous changes and causes endless loop

**Describe the bug**
When using agent mode, if the agent needs to make changes in steps, the first set of changes gets reverted by the second set of changes, which causes the agent to attempt to fix it by redoing the first changes, which reverts the second set of changes, and it gets into an endless loop of trying to fix this.

**Versions**
- Copilot for Xcode: 0.40.0
- Xcode: 16.4
- macOS: 15.5

**Steps to reproduce**
1. Use agent mode to request changes to a single file. The agent needs to make changes in multiple steps. For example, adding a property first, then changing a function to use that property.
2. Observe the agent making the first change successfully.
3. When the agent then makes the second change, it reverts the first change when applying the second.
4. The agent then realizes the first change isn't there, and so it decides to fix this.
5. When re-applying the first change, it ends up reverting the second change.
6. The agent then realizes this too, and attempts to fix it, which puts it into an endless loop.

**Screenshots**

**Logs**
[github-copilot-for-xcode.log](https://github.com/user-attachments/files/21413399/github-copilot-for-xcode.log)

**Additional context**