Accuracy
Chart Accuracy Changelog
A computed chart can be wrong — which is exactly why it can be checked and corrected. This is every correction we've made to the engine, in the open.
Ask a general chatbot for a Zi Wei chart and it will produce one confidently, with no way for you to tell which parts it invented. That version of the chart has no changelog — not because it never errs, but because nothing about it is checkable.
July 29, 2026
Transformations landing on auxiliary stars were being dropped
When one of the Four Transformations fell on an auxiliary star (Left Assistant, Right Guardian, Literary Arts, Literary Talent) rather than a major star, it was silently omitted from the chart. Four of the ten heavenly stems place at least one transformation on an auxiliary star, so this affected a meaningful share of charts. They now show.
July 29, 2026
Era-level transformations could inherit the wrong stem
The decade (Era) layer sometimes carried the transformations of the layer above it instead of resolving from its own palace stem. The wheel and the written reading now both read from a single layered source, so what you see on the chart and what the reading describes can no longer disagree.
July 29, 2026
Year boundaries now fall at 立春, not January 1
The Chinese solar year begins at 立春 (start of spring, around February 4) — not at New Year. Selecting a year or a decade in January or early February could render the previous year’s transformations. Every path into a year view — the selector, the Now button, the Reset button — now resolves to the correct 干支 year.
July 29, 2026
Readings now receive the chart in classical terms
The written reading is translated from the computed chart. Stars and transformations are now passed to that step in the classical vocabulary, with the natal and Era layers explicitly separated — closing the gap where a reading could blur which layer a transformation belonged to.
July 19, 2026
Charts cast before signing in are no longer lost
If you cast a chart while logged out and then signed in, your birth details were not always saved to the account, and the chart had to be re-entered. Both the sign-in and the checkout round trip now return you to the exact chart you were looking at.
Chart accuracy comes before everything else here. If something in your chart looks wrong, tell us — team@purpletome.com. Interpretation is a separate matter: classical schools genuinely differ on some points, and we follow one consistently.