feat: product neutral guides

[bshaffer]

Submitting the DRAFT PR for early feedback

• Add Product Neutral Guide markdown files to docs/, and add them to guide_source_files
• Cleanup the copied README.md so it does not contain broken links on devsite.
• Add sample import using syntax [code-cpp[](FILENAME#SAMPLE)]
• Test remaining cpp samples by hand

[gemini-code-assist]

Summary of Changes

Hello @bshaffer, 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 establishes the foundational framework for incorporating product-neutral documentation guides into the existing DocFX build system. It introduces a new CMake module to handle the copying and structuring of these generic guides, beginning with the project's README.md as a 'Getting Started' entry. The changes also extend Doxygen's configuration capabilities to allow for more granular control over file pattern inclusion. This is a work-in-progress, laying the groundwork for future documentation expansion.

Highlights

• Enhanced Doxygen Configuration: The google_cloud_cpp_doxygen_targets_impl CMake function now supports a FILE_PATTERNS option, offering more flexibility in specifying which files Doxygen should process for documentation generation.
• Introduced Product-Neutral Guide Infrastructure: A new docfx/product-neutral-guides subdirectory and associated CMake logic have been added to manage and build documentation guides that are not specific to a single product, laying the groundwork for generic documentation.
• Initial Guide Integration: The main README.md is now copied and integrated as a 'Getting Started' guide within the DocFX build process, complete with a corresponding entry in the generated Table of Contents.

🧠 New Feature in Public Preview: You can now enable Memory to help Gemini Code Assist learn from your team's feedback. This makes future code reviews more consistent and personalized to your project's style. Click here to enable Memory in your admin console.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in pull request comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request introduces the build infrastructure for product-neutral guides. It adds a new CMake sub-project to copy guide files and generate a table of contents for docfx. The changes in GoogleCloudCppDoxygen.cmake to allow custom file patterns are well-implemented.

My review focuses on the new docfx/product-neutral-guides/CMakeLists.txt file. I've identified a potential issue with YAML generation if display names contain special characters, and a more significant build-ordering problem where the table of contents is generated at configure-time while the files it references are generated at build-time. Addressing these will make the new build logic more robust.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.95%. Comparing base (fa35817) to head (3cc3746).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #15865      +/-   ##
==========================================
- Coverage   92.96%   92.95%   -0.01%     
==========================================
  Files        2460     2460              
  Lines      228931   228931              
==========================================
- Hits       212826   212811      -15     
- Misses      16105    16120      +15     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[bshaffer]

@scotthart The kokoro job for macosx cmake-vcpkg seems to be failing with the error "module 'OpenSSL.crypto' has no attribute 'sign'":

2026-01-27T22:31:42Z (+1933s): + gsutil ls gs://cloud-cpp-kokoro-results/
module 'OpenSSL.crypto' has no attribute 'sign'
2026-01-27T22:31:50Z (+1941s): build script reported errors.
2026-01-27T22:31:50Z (+1941s): cleaning up artifacts.
rm -rf /tmpfs/src/github/google-cloud-cpp/cmake-out


[ID: 6316214] Command finished after 2063 secs, exit value: 1


Warning: Permanently added 'localhost' (ED25519) to the list of known hosts.
[14:31:52 PST] Collecting build artifacts from build VM
Build script failed with exit code: 1

I'm unsure however, as I do not think anything I did would cause this. Let me know if you have any thoughts on how I can resolve it!

[scotthart]

@scotthart The kokoro job for macosx cmake-vcpkg seems to be failing with the error "module 'OpenSSL.crypto' has no attribute 'sign'":

2026-01-27T22:31:42Z (+1933s): + gsutil ls gs://cloud-cpp-kokoro-results/
module 'OpenSSL.crypto' has no attribute 'sign'
2026-01-27T22:31:50Z (+1941s): build script reported errors.
2026-01-27T22:31:50Z (+1941s): cleaning up artifacts.
rm -rf /tmpfs/src/github/google-cloud-cpp/cmake-out


[ID: 6316214] Command finished after 2063 secs, exit value: 1


Warning: Permanently added 'localhost' (ED25519) to the list of known hosts.
[14:31:52 PST] Collecting build artifacts from build VM
Build script failed with exit code: 1

I'm unsure however, as I do not think anything I did would cause this. Let me know if you have any thoughts on how I can resolve it!

It's a known issue, unrelated to this PR.