Net Loss Per Share - Schedule of Potentially Dilutive Common Stock Equivalents Excluded From Computation of Diluted Net Loss Per Share (Details) - shares shares in Thousands	6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	64,750	59,273
Common stock warrants
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	41,918	36,783
Legacy GCT
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	20,000	20,000
Unvested restricted stock units
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	1,430	1,071
Sponsor Earnout Shares
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	571	571
Convertible promissory notes
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	500	500
Options issued and outstanding
Net Loss Per Share
Potentially dilutive common stock equivalents that were excluded from the computation of diluted net loss per common share (in shares)	331	348