name: bazi-pillars-from-datetime description: Deterministic four-pillar (bazi) calculation from datetime.

Scope

This skill defines a deterministic, reproducible calculation contract for four pillars (year/month/day/hour) from a Gregorian datetime. It must not generate user-facing prose or interpretations.

Inputs (JSON)

{ "datetime": "YYYY-MM-DDTHH:MM:SS", "timezone": "IANA/Timezone", "location": { "name": "City/Region", "longitude": 0.0, "latitude": 0.0, "lookup_mode": "auto|local|online", "lookup_provider": "nominatim|amap|tencent", "lookup_key": "optional-api-key", "lookup_path": "/path/to/cities.json", "cache_path": "/path/to/city_cache.json", "lookup_timeout": 6 }, "gender": "female|male|other", "rules": { "year_boundary": "lichun", "month_rule": "solar_terms", "day_boundary": "00:00", "time_correction": "mean_solar_time", "require_dayun": false }, "flows": { "datetime": "YYYY-MM-DDTHH:MM:SS", "timezone": "IANA/Timezone" }, "mode": "strict" }

Notes

• datetime has no offset; interpret it in timezone.
• timezone is required; if defaulted by the caller, record it in notes.
• location is required when time_correction=mean_solar_time or true_solar_time. Prefer longitude/latitude. If only name is provided, the skill will resolve it by:
  • local map (lookup_path) when lookup_mode is local or auto
  • online geocoding when lookup_mode is online or auto
• lookup_provider defaults to nominatim. For amap/tencent, provide lookup_key (or set env BAZI_GEOCODE_KEY).
• lookup_path defaults to ./cities.json next to main.py.
• cache_path defaults to ./city_cache.json next to main.py.
• You can override defaults via env:
  • BAZI_CITY_MAP_PATH, BAZI_CITY_CACHE_PATH
  • BAZI_GEOCODE_PROVIDER, BAZI_GEOCODE_KEY, BAZI_GEOCODE_TIMEOUT
• gender is required when requesting dayun (大运) calculation. If require_dayun=true and gender is missing, return MISSING_GENDER.
• rules is optional; defaults are fixed as above.
• flows is optional. When provided, the skill returns 流年/流月/流日 based on the given datetime. If omitted, flow data is not returned.
• mode defaults to strict.
• Lunar calendar is not used.

Outputs (success)

{ "ok": true, "bazi": { "year": { "tg": "...", "dz": "..." }, "month": { "tg": "...", "dz": "..." }, "day": { "tg": "...", "dz": "..." }, "hour": { "tg": "...", "dz": "..." } }, "dayun": { "direction": "forward|backward", "start_age_years": 0.0, "start_age_months": 0.0, "start_datetime": "YYYY-MM-DDTHH:MM:SS", "cycles": [ { "index": 1, "tg": "...", "dz": "...", "gz": "...", "start_age_years": 0.0, "start_datetime": "YYYY-MM-DDTHH:MM:SS", "end_datetime": "YYYY-MM-DDTHH:MM:SS" } ] }, "flows": { "datetime": "YYYY-MM-DDTHH:MM:SS", "year": { "tg": "...", "dz": "...", "gz": "..." }, "month": { "tg": "...", "dz": "...", "gz": "..." }, "day": { "tg": "...", "dz": "...", "gz": "..." } }, "solar_terms": { "prev": { "name": "...", "datetime": "..." }, "next": { "name": "...", "datetime": "..." } }, "meta": { "timezone": "IANA/Timezone", "rules_used": { "year_boundary": "lichun", "month_rule": "solar_terms", "day_boundary": "00:00" }, "true_solar_time": { "method": "mean_solar_time|true_solar_time", "datetime": "...", "delta_minutes": 0.0, "equation_of_time_minutes": 0.0, "longitude_correction_minutes": 0.0 }, "confidence": "high|medium|low", "notes": [] } }

Outputs (failure)

{ "ok": false, "error": { "code": "INVALID_DATETIME|INVALID_TIMEZONE|INVALID_LOCATION|MISSING_DATE|MISSING_TIME|MISSING_LOCATION|MISSING_GENDER", "missing": ["date|time|timezone|location|gender"], "message": "Human-readable error for agent use" } }

Fixed rules

• Year boundary: lichun
• Month boundary: split by solar terms
• Day boundary: 00:00
• Time correction:
  • mean_solar_time (default): longitude correction only
  • true_solar_time: longitude correction + equation of time
• require_dayun: false (set true only when user requests dayun)
• Day pillar base: 1984-02-02 is 丙寅日 (used as reference)

Missing time handling

• strict mode: return MISSING_TIME if hour is missing or ambiguous.
• lenient mode (not default): return candidates and set confidence=low.

Tests (minimum)

• Before/after lichun (year boundary)
• Around solar term boundaries (month boundary)
• Day boundary at 00:00
• Timezone shifts (same UTC, different local date)
• Missing time (strict error)

Implementation

Entry point: main.py (reads JSON from stdin, prints JSON). Example:

echo '{"datetime":"1998-08-12T15:30:00","timezone":"Asia/Shanghai","location":{"name":"广州"},"rules":{"time_correction":"true_solar_time"}}' | python3 main.py