Regression prevention and quality gates

Problem

Chart rendering defaults are fragile to code changes — a refactor to axis scaling can silently shift label positions, a color palette update can break contrast ratios, and a new chart type can inadvertently alter shared rendering utilities. Currently, there are no automated gates that catch visual regressions before they reach users. Without visual regression tests (SVG snapshot comparisons), automated accessibility checks, and CI-enforced quality thresholds on the render pipeline, every release carries the risk of degrading chart quality in ways that are invisible until users report them.

Context

• Manual review is not enough to protect visual language, chart defaults, interaction behavior, and differentiated styling once the change rate increases; regressions will keep shipping unless the highest-value checks become automatic.
• This task should identify what needs gating in CI or structured review and what evidence is sufficient to block a risky change before it reaches users.
• Expected touchpoints include dataface/core/render/chart/, chart design docs, examples, and visualization test coverage, automated tests, eval/QA checks, and any release or review scripts that can enforce the new gates.

Possible Solutions

• A - Add only a few narrow tests around current bugs: easy to land, but it rarely protects the broader behavior contract.
• B - Recommended: define a regression-gate bundle around the core behavior contract: combine focused tests, snapshots/evals, and required review evidence for risky changes.
• C - Depend on manual smoke testing before each release: better than nothing, but too inconsistent to serve as a durable gate.

Plan

1. Identify the highest-risk behavior contracts for visual language, chart defaults, interaction behavior, and differentiated styling and the types of changes that should be blocked when they regress.
2. Choose the smallest practical set of automated checks and required review evidence that covers those contracts well enough to matter.
3. Wire the new gates into the relevant test, review, or release surfaces and document when exceptions are allowed.
4. Trial the gates on a few representative changes and tighten the signal-to-noise ratio before expanding the coverage further.

Implementation Progress

Review Feedback

• [ ] Review cleared