M1 consistent category color mapping across charts

Problem

Investigate and design a top-level category color mapping system so repeated semantic values such as Accessories, Electronics, and Tools keep the same colors across every chart. Explore API shapes including a top-level color underscore map attribute that accepts either an ordered value list from a query or inline values, plus an explicit value-to-color map. Define how ordering and manual color assignment should interact, how mappings apply automatically across chart types, and how the renderer should resolve colors consistently when charts share categorical domains.

Context

• Cross-chart category colors are currently resolved locally, which weakens dashboard-level semantic consistency.
• The solution needs to work across chart families without turning palette logic into ad hoc overrides everywhere.
• This sits near palette research, theme defaults, and dashboard-level visual coherence work.

Possible Solutions

• A - Let each chart assign colors independently and accept drift between repeated categories: simplest, but preserves the problem.
• B - Require authors to hardcode value-to-color mappings in every chart: explicit, but repetitive and error-prone.
• C - Recommended: define a top-level categorical mapping system with shared domain order, optional explicit overrides, and automatic reuse across charts.

Plan

1. Catalog the current color-assignment behavior and the real failure cases on dashboards.
2. Propose the authored API for shared category mapping, ordering, and manual overrides.
3. Define renderer resolution rules across chart types and missing-domain situations.
4. Add representative examples and tests that prove cross-chart consistency.

Implementation Progress

Review Feedback

• [ ] Review cleared

2026-03-22 Triage Decision

• Status set to planned (active backlog, not obsolete): no implementation or PR exists yet; requirement still aligns with current graph-library direction for cross-chart visual consistency.