Anchor phase charts' Y axis at 0 via symlog

[bvdmitri]

What

The Time phases and Time phases across scenarios charts defaulted to a log scale whose Y axis floated (domain={["auto", "auto"]}) and did not start at 0. This anchors the Y axis at 0 in every mode.

A true log axis can't include 0 (log(0) is undefined), so the log-like view now uses symlog (symmetric / pseudo-log): log-like spacing for large values, linear near the origin, and it includes 0. Recharts v3 supports "symlog" natively as a string scale type, so no new dependency was added.

Change

Both charts render through the shared PhaseBars component, so a single edit covers them:

// before
scale={effectiveLog ? "log" : "linear"}
domain={effectiveLog ? ["auto", "auto"] : [0, "auto"]}
// after
scale={effectiveLog ? "symlog" : "linear"}
domain={[0, "auto"]}

The domain is now unconditionally [0, "auto"], so the axis starts at 0 in the log-like, linear, and stacked modes.

Tests

Adds a direct PhaseBars.test.tsx (the component had none) that mocks the Recharts primitives and asserts the YAxis gets scale="symlog" with a domain anchored at 0 by default, and stays anchored at 0 in linear and stacked modes. Written test-first per the repo's TDD rule.

• npm test — 161 passed
• npx tsc --noEmit + npm run lint — clean

Note

The toggle/caption still read "log scale" — symlog reads as a log-like scale to users. Happy to relabel to "symlog"/"pseudo-log" if preferred.

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