# Fengshui Calculator

> A verifiable calculation tool for traditional Chinese feng shui and calendar systems: BaZi four pillars, Xuan Kong flying stars, Ming Gua / Kua numbers, 24 mountains, date selection, true solar time, and terrain checks. Every result carries provenance (engine version + ruleset id + SHA-256 input digest) and is reproducible; the engine is cross-checked against the Hong Kong Observatory 1901–2100 and four open-source reference implementations (~290,000 samples). Cultural and educational use — not predictions.

- Tools run entirely in the browser (WebAssembly, zero network for calculations; birth data never leaves the device).
- Public REST API (`/v1/*`) and native MCP endpoint (`/v1/mcp`, 10 tools) are keyless and free-tier rate-limited; Pro raises the quota 10×.
- Rules are registered with their classical sources, including doubted attributions flagged rather than hidden; unreconcilable school disputes are presented side by side, never merged.

## Core calculators

- [Four-pillar chart (BaZi)](https://fengshuicalculator.com/): instant birth chart, both year conventions × both day boundaries returned side by side.
- [Flying star calculator](https://fengshuicalculator.com/flying-star-calculator/): Xuan Kong chart with pattern labels and adjudicated sitting/facing bands.
- [Kua number calculator](https://fengshuicalculator.com/kua-number-calculator/): Ming Gua with the exact Lichun instant applied.
- [Kua number by birth year](https://fengshuicalculator.com/kua-by-year/): male/female Kua for every year 1901–2100.
- [Chinese zodiac calculator](https://fengshuicalculator.com/chinese-zodiac-calculator/): Lichun-boundary animal and year pillar.
- [Zodiac by year](https://fengshuicalculator.com/zodiac/): exact Lichun and Chinese New Year instants, 1901–2100.
- [Date selection](https://fengshuicalculator.com/date-selection/): twelve day officers, month pages, two-system warnings.
- [Daily almanac](https://fengshuicalculator.com/almanac/): lunar date, day officer, yellow/black path, six officers — with calendar-basis notes.
- [24 mountains converter](https://fengshuicalculator.com/24-mountains-degrees/): degrees ↔ mountain, adjudication surfaced.
- [True solar time](https://fengshuicalculator.com/true-solar-time/): equation of time and longitude correction by city.
- [Describe what you need](https://fengshuicalculator.com/ask/): deterministic router (not an AI) to the right tool with parameters filled in.

## API and agents

- [Developer docs](https://fengshuicalculator.com/docs/): REST + MCP overview.
- [REST reference](https://fengshuicalculator.com/docs/api/): endpoints, parameters, rate limits, license tier.
- [MCP setup](https://fengshuicalculator.com/docs/mcp/): JSON-RPC endpoint for Claude Desktop / Cursor / any MCP client.
- [Fingerprint format (FIF)](https://fengshuicalculator.com/docs/fif/): JCS + SHA-256 reproduction format.
- [Skill card](https://fengshuicalculator.com/.well-known/skills/fengshui-calculator/SKILL.md): agent-facing skill definition.

## Verification and scholarship

- [Verify a chart](https://fengshuicalculator.com/verify/): replay an input digest in the browser.
- [Accuracy report v1](https://fengshuicalculator.com/audit/report-v1.html): measured accuracy, every divergence attributed.
- [Rule provenance register](https://fengshuicalculator.com/rules/): every kernel rule with its classical source and verification method (machine-readable JSON included).
- [Classical texts register](https://fengshuicalculator.com/texts/): 28 texts collated with attribution status.
- [School dispute register](https://fengshuicalculator.com/disputes/): irreconcilable rules presented side by side.
- [Errata](https://fengshuicalculator.com/errata/): public corrections log.
- [Glossary](https://fengshuicalculator.com/glossary/): 23 entries, each stating how the engine computes it.

## Optional

- [Pro pricing](https://fengshuicalculator.com/pro/): workflow tier (batch charts, exports, 10× API quota); free tier is a permanent charter.
- [Engine comparison](https://fengshuicalculator.com/compare/): three real engines side by side on the same input.