fix: keep extra manifest paths portable

[young5lee]

Problem

When using extraConfigPaths / extraSecretPaths, sync-push writes extra-manifest.json with absolute sourcePath values (because paths are normalized via path.resolve()/home expansion).

Across machines/OSes this causes churn (/home/... vs /Users/...) and can lead to extras being skipped on pull (allowlist mismatch), then removed on the next push.

Fix

• Store sourcePath in extra-manifest.json using a portable ~ form when the path is under the user's home directory.
• Keep the allowlist normalized/absolute for matching.
• Expand ~ when copying/stat-ing extra paths so runtime behavior stays correct.

Tests

• Added coverage for portable sourcePath behavior in src/sync/paths.test.ts.

[gemini-code-assist]

Summary of Changes

Hello @young5lee, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses an issue where extra-manifest.json stored absolute paths for extra configurations and secrets, leading to inconsistencies and potential failures across different environments. The solution introduces a mechanism to store home directory paths in a portable tilde-prefixed format within the manifest, while ensuring that these paths are correctly resolved to their absolute form during file system operations. This change improves cross-platform compatibility and reduces unnecessary churn in the manifest file.

Highlights

• Portable Path Storage: Modified the extra-manifest.json to store sourcePath values using a portable tilde (~) form when paths are located within the user's home directory. This prevents churn across different machines and operating systems.
• Runtime Path Expansion: Ensured that ~ prefixed paths are correctly expanded to their absolute form during runtime operations, such as copying files, checking path existence, and stat-ing files, to maintain correct functionality.
• Allowlist Consistency: Maintained the allowlist of extra paths in a normalized and absolute format for accurate matching, separating it from the portable storage format.
• New Test Coverage: Added new test cases to src/sync/paths.test.ts to validate the behavior of portable sourcePath storage and ensure paths outside the home directory remain absolute.

Changelog

• src/sync/apply.ts
  • Imported the expandHome utility function.
  • Updated localPath resolution to use expandHome and path.resolve for entry.sourcePath.
  • Modified file system operations (pathExists, fs.stat, copyDirRecursive, copyFileWithMode) to use the newly resolved actualSourcePath.
• src/sync/paths.test.ts
  • Added a test case to verify that extra manifest sourcePath values are stored using portable home paths (e.g., ~/.config/opencode/custom.json).
  • Added a test case to confirm that extra manifest sourcePath values remain absolute when outside the home directory (e.g., /etc/hosts).
• src/sync/paths.ts
  • Introduced a new collapseHome function to convert absolute paths under the home directory into a tilde-prefixed format.
  • Modified buildExtraPathPlan to use collapseHome when generating portablePaths for extra.entries.
  • Ensured that the allowlist continues to use normalizePath to maintain absolute paths for matching purposes.

Activity

• No specific activity (comments, reviews) has been recorded for this pull request yet.

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[gemini-code-assist]

Code Review

This pull request effectively addresses the issue of non-portable paths in extra-manifest.json by introducing a ~-based home directory representation for paths. However, a high-severity path traversal vulnerability was identified in applyExtraPaths. This vulnerability arises because the repoPath from the repository's manifest is trusted without validation, which could allow a malicious repository to exfiltrate arbitrary files from a user's machine. It is recommended to validate that all paths from the manifest are relative and stay within the expected repository boundaries. Additionally, there is one suggestion to improve code clarity in src/sync/paths.ts.

[gemini-code-assist]

The applyExtraPaths function trusts the repoPath value from the extra-manifest.json file in the repository. If this value is an absolute path or contains path traversal sequences (e.g., ../../), it can point to arbitrary files on the user's system. Since this path is used as the source for a copy operation where the destination is an allowlisted local path, an attacker who controls the repository can trick the system into copying sensitive files (like /etc/shadow or SSH keys) into the sync directory. A subsequent sync-push would then upload these sensitive files to the repository, leading to data exfiltration. Additionally, the mode property from the manifest is used in chmod without validation, allowing an attacker to change permissions of allowlisted files.

[gemini-code-assist]

For improved clarity, consider generating the allowlist directly from rawPaths. This would make the data flow more direct, as rawPaths would be the single source for both the runtime allowlist of absolute paths and the portablePaths for the manifest. This change improves readability without affecting functionality.

Suggested change

	const allowlist = portablePaths.map((entry) =>
	normalizePath(entry, locations.xdg.homeDir, platform)
	);
	const allowlist = rawPaths.map((entry) =>
	normalizePath(entry, locations.xdg.homeDir, platform)
	);