code-review-workflow

name	code-review-workflow
description	Provides guidance and best practices on Gerrit submission labeling, CI builder execution, Python code formatting/linting, commit metadata standardization, and testing strategy in git-repo.

Code Review Workflow Engineering Guide

Executive Summary

Welcome to the authoritative engineering guide for the Code Review Workflow. This living repository exists to capture critical folk knowledge, prevent the recurrence of historical failure modes, and enforce strict architectural and procedural boundaries across our integration pipeline. By standardizing these protocols, we ensure high development velocity while maintaining rock-solid codebase stability and traceability.

This guide covers the complete lifecycle of a change list (CL) from local development to automated submission. It defines the strict Gerrit labeling mechanisms required to trigger the Commit-Queue, mandates comprehensive CI builder environment checks, and enforces centralized Python static analysis. Furthermore, it outlines uncompromising standards for atomic commit metadata and pragmatic testing state isolation to guarantee that every integration is fully bisectable and verifiable.

For incoming engineers, adherence to these mandates eliminates the friction of stalled pipelines, unreviewable monolithic changes, and silent CI regressions. Treat this guide as your primary roadmap for navigating the repository's strict submission requirements, enabling seamless transitions from peer approval to successfully integrated code.

Summary

Chapter Theme / Title	Scope & Objective
**Gerrit Submission and Labeling	Dictates strict access controls, review
: Workflow** : enforcement protocols, and Gerrit :
: : labeling mechanisms required to advance :
: : changes through the CI pipeline, ensuring :
: : seamless transitions to automated :
: : integration via the Commit-Queue. :
**CI Builder Environment and	Defines guidelines for ensuring build
: Execution Integrity** : script resilience against missing :
: : dependencies and managing process :
: : execution contexts within LUCI and local :
: : testing environments to prevent silent :
: : builder failures. :
**Python Code Formatting and	Governs the automated enforcement of
: Linting** : Python style guidelines, mandating strict :
: : PEP-8 compliance, import sorting, and :
: : consistent string quoting to ensure :
: : codebase uniformity and prevent CI :
: : regressions. :
**Commit Metadata and History	Establishes the structural composition
: Standardization** : and metadata formatting of change lists :
: : (CLs) to ensure precise issue tracker :
: : integration, reliable CI/CD parsing, and :
: : an atomic, bisectable repository history. :
**Testing Strategy and State	Outlines test implementation boundaries,
: Isolation** : emphasizing pragmatic mocking limits to :
: : prevent false positives and detailing :
: : acceptable workflows for deferred test :
: : coverage while maintaining verification :
: : integrity. :

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Chapter: Gerrit Submission and Labeling Workflow

Context: This domain dictates the strict access controls, review enforcement protocols, and specific Gerrit labeling mechanisms required to advance changes through the CI pipeline. Adherence ensures seamless transitions from peer approval to automated integration via the Commit-Queue.

Summary

| Rule ID | Principle / Constraint | Priority | Primary Symptom / | : : : : Trap : | :-------- | :------------------------------ | :------- | :----------------- | | T1-01 | Explicit Labeling for Gerrit | High | Leaving a change | : : Automated Submission : : idle after : : : : : addressing : : : : : comments or : : : : : receiving a : : : : : reviewer's LGTM, : : : : : expecting the : : : : : reviewer to merge : : : : : it. : | T1-02 | Automated Submission via | Medium | Requesting a | : : Commit-Queue (CQ) : : manual push or : : : : : direct submit from : : : : : repository : : : : : maintainers after : : : : : receiving code : : : : : review approval. : | T1-03 | Gerrit Trusted Contributor | Medium | Relying on a | : : Review Enforcement Verification : : standard +2 vote : : : : : from a non-trusted : : : : : contributor to : : : : : fulfill strict : : : : : Review-Enforcement : : : : : requirements. : | T1-04 | Mandatory Gerrit Labels for | High | Acknowledging an | : : Automated Submission : : approval but : : : : : failing to apply : : : : : the appropriate : : : : : Gerrit labels to : : : : : initiate the merge : : : : : pipeline. : | T1-05 | Gerrit Automated Submission | Medium | Leaving an | : : Triggers : : approved patchset : : : : : idle and waiting : : : : : for maintainers to : : : : : manually merge it. : | T1-06 | Active Reviewer Rerouting for | Medium | Waiting weeks or | : : Stalled Changes : : months for an : : : : : inactive or OOO : : : : : reviewer to : : : : : respond to a : : : : : patchset update. :

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Rules

T1-01: Explicit Labeling for Gerrit Automated Submission

Rule: Always apply Verified+1 and Commit-Queue+2 explicitly to trigger the final submission phase. Never assume a code approval automatically initiates the pipeline.

What: Changes are not merged automatically upon receiving approval; contributors must explicitly set the Verified+1 and Commit-Queue+2 labels to trigger the final submission phase.

Applies To: Gerrit review UI and change submission pipeline as defined in CONTRIBUTING.md.

Why: Contributors often mistakenly assume an LGTM implies an immediate merge, leading to stalled changes. The project relies on explicitly triggering the Commit-Queue to finalize CI checks and perform the merge. Failing to adhere to this typically results in Stalled Submission Pipeline.

Trap 1: Leaving a change idle after addressing comments or receiving a reviewer's LGTM, expecting the reviewer to merge it.

Don't:

• Waiting indefinitely after reviewer posts 'LGTM'.

Do:

• Vote Verified+1 and Commit-Queue+2 manually to submit the change to the automated queue.

Exceptions: Contributors lacking trusted permissions must ping a repository maintainer to apply the final Commit-Queue+2 vote.

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T1-02: Automated Submission via Commit-Queue (CQ)

Rule: Must utilize the Gerrit Commit-Queue (CQ) labeling system to merge code. Maintainers must never perform direct manual submissions.

What: Merging code must be triggered via the Gerrit Commit-Queue (CQ) labeling system rather than relying on direct manual submission by maintainers.

Applies To: Gerrit code review UI and CI/CD submission workflow.

Why: Contributors would request maintainers to directly merge patches once approved, bypassing the automated commit-queue pipeline, which guarantees that final integration tests pass before pushing to the target branch. Failing to adhere to this typically results in Bypassed CI / Direct Submit.

Trap 1: Requesting a manual push or direct submit from repository maintainers after receiving code review approval.

Don't:

• Leaving a comment: "I believe everything is ready for integrating this. So if either of you can submit it, it would be appreciated."

Do:

• Applying the Commit-Queue+2 (CQ+2) label in Gerrit, which delegates testing and the final merge operation to the automated bot.

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T1-03: Gerrit Trusted Contributor Review Enforcement Verification

Rule: Verify review enforcement requirements are satisfied by contributors within the explicitly configured trusted group. Never cast misleading +2 votes if you lack valid trusted group privileges.

What: Gerrit submission requirements may mandate specific approval levels (e.g., two trusted contributors). Votes from users with +2 access who are not in the designated 'trusted' group do not satisfy the 'Review-Enforcement' submit requirement.

Applies To: Gerrit repository administration and code review voting workflows.

Why: Non-trusted contributors with +2 rights were casting +2 votes on changes. These votes did not fulfill the 'Two trusted contributors' Review-Enforcement requirement, leading to stalled submissions and confusion regarding why the UI showed a +2 but blocked submission. Failing to adhere to this typically results in Blocked Submission / Silent Requirement Failure.

Trap 1: Relying on a standard +2 vote from a non-trusted contributor to fulfill strict Review-Enforcement requirements.

Don't:

• Leaving a +2 vote on a change as a non-trusted contributor, creating the false appearance that the Review-Enforcement requirement has been partially or fully met.

Do:

• Verifying the reviewer is in the explicitly configured trusted group for the repository. If not, the reviewer should manually downgrade their invalid +2 vote to a +1 to clearly indicate that their vote does not count toward the enforcement threshold.

Exceptions: Repositories where specific non-employee groups have been explicitly added to the trusted administrators list.

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T1-04: Mandatory Gerrit Labels for Automated Submission

Rule: Always apply Verified+1 and Commit-Queue+2 labels to initiate the CI merge process. Never leave an approved CL in a technically unlabeled state.

What: A code change must receive explicit Verified+1 and Commit-Queue+2 labels by the author or reviewer to trigger the automated CI merge process.

Applies To: Gerrit workflow / Merge execution phase.

Why: Historically, leaving a Change List (CL) in an approved but unlabeled state causes the integration pipeline to stall indefinitely, requiring manual intervention or reviewer pinging to trigger the CI queue. Failing to adhere to this typically results in Merge Pipeline Stall.

Trap 1: Acknowledging an approval but failing to apply the appropriate Gerrit labels to initiate the merge pipeline.

Don't:

• Leaving the CL in an approved state and waiting for auto-submission without applying the Verified+1 or Commit-Queue+2 labels.

Do:

• Explicitly applying Verified+1 (and Commit-Queue+2 if ready) once reviewers have approved the logic, to instruct the automation to merge the code.

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T1-05: Gerrit Automated Submission Triggers

Rule: Must actively signal patch readiness to Gerrit systems using proper label thresholds. Avoid leaving patchsets idle assuming upstream maintainer action.

What: A patchset requires specific label thresholds ('Verified+1' and 'Commit-Queue+2') to trigger automated submission in the Gerrit workflow.

Applies To: Gerrit review UI and automated CI/CD submission process for the git-repo codebase.

Why: Contributors frequently asked how to integrate changes after receiving an approval, leading to stalled patches because the automated pipeline was not explicitly triggered. Failing to adhere to this typically results in Stalled Patch Integration.

Trap 1: Leaving an approved patchset idle and waiting for maintainers to manually merge it.

Don't:

• Waiting indefinitely after receiving an 'LGTM' without setting workflow labels.

Do:

• The patch author manually sets the 'Verified' flag (if locally tested) and applies the 'Commit-Queue+2' vote to signal readiness for automated merge.