feat: allow writes to /tmp by default without permission prompt

[remorses]

Add Filesystem.isAllowedPath() helper that allows access to project directory, os.tmpdir(), and /tmp without prompting for external directory permission.

Fixes #5386
Fixes #4743

[Copilot]

Pull request overview

This PR introduces a new helper function Filesystem.isAllowedPath() to enable file operations in temporary directories (os.tmpdir() and /tmp) without prompting users for external directory permissions. This addresses issues #5386 and #4743 by allowing AI agents to write to temp directories by default, which is a common and safe operation.

Key changes:

• Added isAllowedPath() helper that checks if a path is within the project directory, system temp directory, or /tmp
• Replaced all Filesystem.contains() calls with Filesystem.isAllowedPath() across file operation tools (read, write, edit, patch) and bash command execution

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
packages/opencode/src/util/filesystem.ts	Added new isAllowedPath() function that allows access to project directory and temp directories
packages/opencode/src/tool/write.ts	Updated to use isAllowedPath() instead of contains() for permission checking
packages/opencode/src/tool/read.ts	Updated to use isAllowedPath() instead of contains() for permission checking
packages/opencode/src/tool/patch.ts	Updated to use isAllowedPath() instead of contains() for permission checking
packages/opencode/src/tool/edit.ts	Updated to use isAllowedPath() instead of contains() for permission checking
packages/opencode/src/tool/bash.ts	Updated to use isAllowedPath() instead of contains() in external directory validation

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[rekram1-node]

/review

[jiyeol-lee]

Can we make it optional for this from the configuration like the following?

"permission": {
  "external_directory": {
    "env:$TMPDIR/test": "allow",
    "*": "deny",
  }
}

[rekram1-node]

yeah that's prolly fine

[remorses]

@jiyeol-lee Why would you like to make it optional? Do you want to prevent the LLM to write to /tmp?

[rekram1-node]

that's what I was wondering too but letting people override that perm in general makes sense, best done in separate pr tho

[jiyeol-lee]

@jiyeol-lee Why would you like to make it optional? Do you want to prevent the LLM to write to /tmp?

@remorses @rekram1-node Yes, I don't want LLM to write, especially read /tmp. I usually have multiple credentials in there temporary and I don't want LLM read things that I didn't expect to do. It would be amazing if we make it configurable by the individual user unless it's a project directory.