What's New in P4 Code Review 2026.4

Released: October 2026

For a complete list of what’s new and bug fixes in this release, see the release notes.

Bring Your Own Key (BYOK) for AI vendors

Users can now configure and manage their own AI vendor API keys in My Profile. This Bring Your Own Key (BYOK) capability allows users to authenticate with supported AI providers using personal credentials, while administrators retain control over feature availability through the Allow personal AI vendor keys setting. When enabled, users can securely manage their own AI vendor access without requiring administrator-managed credentials. To learn more, see Personal AI vendors.

Flexible AI vendor selection

Users can now configure and manage their own AI vendor API keys in My Profile. Personal AI vendors supplement administrator-managed AI vendors rather than replace them, allowing users to select from both sets of vendors when using AI-powered features. Administrators retain control over whether personal AI vendors are available.

File tree view for review files

The review page now includes a file tree view that displays changed files in their folder hierarchy. This makes it easier to navigate large reviews and locate files within complex directory structures. To learn more, see Files and diffs.

Always-visible review version selector

The review version selector is now always visible on the review page, allowing reviewers to switch between review versions more easily while maintaining their place within the review.

Sticky review actions

Common review actions remain accessible as you navigate the review page. This includes actions such as changing the review state, reducing the need to scroll back to the top of the page.

Enhanced comment discussions

Comment discussions now use a flat layout that maintains parent-child relationships using quote belts rather than nested indentation. This improves readability for large review discussions and removes the horizontal space constraints associated with deeply nested comment hierarchies. Comment threads can continue growing without depth limitations while still allowing users to identify and navigate reply relationships.

Review page improvements

Several improvements and fixes have been made to the review experience, including:

  • Files are collapsed by default when a review is opened.

  • Whitespace difference indicators now display correctly.

  • Resolved a syntax-highlighting issue affecting collapsed diff regions.

  • Improved image diff scaling and background rendering.

  • Diff view preferences, such as line wrapping and display mode, now persist across sessions.

  • Fixed issues affecting side-by-side diffs, unchanged content detection, sidebar positioning, and approval workflows for reviews containing binary files.

  • The review page has been refreshed with updated diff colors, improved typography, and a number of usability improvements and fixes.

Documentation for API request rate limiting

Added documentation describing how to configure rate limiting for API requests using supported web server technologies. This guidance can help protect P4 Code Review deployments from excessive or abusive traffic. To learn more, see Rate limiting API requests.

Prevent state changes after approval and commit

Administrators can now prevent review state changes after a review has been approved and committed by enabling the disable_state_change_after_commit configurable. When enabled, approved and committed reviews are locked and cannot be moved to another review state. To learn more, see Disable state change after commit.

Reliability and security improvements

P4 Code Review 2026.4 includes several reliability, performance, and security enhancements:

  • Improved WebSocket gateway reliability, connection management, and client validation. Added support for trusted proxy configuration through the TRUSTED_PROXIES environment variable, improving client IP handling when P4 Code Review is deployed behind load balancers, reverse proxies, and CDNs.

  • Enhanced internal locking to prevent rare concurrency issues during simultaneous updates.

  • Hardening of trigger script processing and validation.

  • Additional security controls for ImageMagick in Docker deployments.

  • Improved validation and security controls for LibreOffice document previews, including conversion timeouts and restricted execution settings.

  • Added the max_scan_rows configurable to limit fallback file search scanning and improve performance on large deployments. To learn more, see Search.

For more information, see the release notes.

Added support for Ubuntu 26.04

P4 Code Review now supports Ubuntu 26.04. To learn more, see Install and configure P4 Code Review on Ubuntu.