Primary fields

Field	Type	Description
bpm	float | null	Detected BPM (tempo)
bpm_confidence	float | null	BPM confidence [0..1]
key	string | null	Musical key (e.g. "A minor")
key_confidence	float | null	Key confidence [0..1]
hz	float | null	A4 tuning frequency in Hz
hz_confidence	float | null	Hz confidence [0..1]
analysis_time	float	Analysis time in seconds
cached	bool	Whether the result was served from cache
analyzer_version	string	Analyzer engine version
source_url	string | null	Normalized source URL (for URL analysis)