fix(output): write JSON-wrapped base64 attachment payloads with --output

[jeevan6996]

Summary

• make --output handle JSON responses that contain base64url binary payloads in a data field (for example gmail.users.messages.attachments.get)
• decode and write bytes to the requested file path instead of silently succeeding without creating a file
• return a clear validation error when --output is used with JSON responses that do not contain a decodable data payload
• add regression tests for decoding behavior and output handling, plus a changeset

Fixes #714

Validation

• could not run local Rust tests in this environment because cargo is not installed (command not found)

[changeset-bot]

🦋 Changeset detected

Latest commit: 5750dc8

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@googleworkspace/cli	Patch

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[gemini-code-assist]

Summary of Changes

Hello, 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 enhances the CLI's handling of JSON responses that contain binary attachments, specifically targeting APIs like Gmail. It ensures that when a user specifies an output file, the CLI correctly identifies, decodes, and persists the binary data rather than ignoring it. The changes also introduce necessary validation to prevent conflicting flag usage and include robust testing to ensure future stability.

Highlights

• Base64 Decoding Support: Implemented logic to detect and decode base64url-encoded binary payloads found within JSON 'data' fields.
• File Output Handling: Updated the --output flag to correctly write decoded binary data to the specified file path instead of failing silently.
• Validation Improvements: Added validation to prevent the use of --output in conjunction with --page-all, and ensured clear error messages for invalid payloads.
• Regression Testing: Added comprehensive unit and integration tests to verify decoding behavior and file writing operations.

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[gemini-code-assist]

Code Review

This pull request enables the --output flag to decode JSON-wrapped base64url payloads and write the binary data to disk. Review feedback identifies a compilation error in the added tests due to an undefined function and suggests that the implementation should fall back to writing raw JSON when no base64 payload is detected to avoid regressions in CLI behavior.

[jeevan6996]

I intentionally kept the behaviour fail-loud for --output when JSON does not contain a decodable base64url data field, because the issue here is silent success with no file written. Returning a clear validation error makes the failure visible and prevents data-loss-style false positives in automation flows. Happy to adjust to a different fallback if maintainers prefer (for example, explicit opt-in to write raw JSON).

[jeevan6996]

Addressed the scope/compile concern: removed the unrelated Tasks warning tests from this PR so it stays focused on issue #714 output decoding behavior. Pushed in 5750dc8.

[googleworkspace-bot]

/gemini review

[gemini-code-assist]

Code Review

This pull request enables the --output flag to decode and save JSON-wrapped base64url payloads, such as Gmail attachments, directly to disk. It introduces a new helper function for base64url decoding, adds validation to prevent the use of --output with --page-all for JSON responses, and includes unit tests to verify the decoding and file-writing logic. I have no feedback to provide as there were no review comments.