feat(chat): support multi file write with reject and open diff

[ctlai95]

Problem

Support workflows with multiple file writes without confirmation

Solution

• Set requiresAcceptance to false for all FsWrite executions
• Store backups of each FsWrite so we can revert the changes if needed

---

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• Your code changes must meet the guidelines in CONTRIBUTING.md.
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[github-actions]

• This pull request implements a feat or fix, so it must include a changelog entry (unless the fix is for an unreleased feature). Review the changelog guidelines.
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[Hweinstock]

why is null needed here?

[ctlai95]

undefined doesn't work because it defaults to having insert to cursor and copy buttons

[Hweinstock]

Don't fully follow here, why do we need an empty string?

[ctlai95]

This is just to make sure we create a chat message for this tool so that we can add a header to it

[Hweinstock]

Is the logic here that for backups that don't exist (i.e. writing to a new file) we return empty content and a flag to say it doesn't exist? Is this the easiest way to handle this case?

[ctlai95]

Yeah, we need some way to differentiate if the backup was a new file creation or the file existed but was empty. I think a flag works best here