| Document and Entity Information | Jun. 20, 2024 |
| Document And Entity Information [Line Items] | |
| Document Type | 8-K |
| Document Period End Date | Jun. 20, 2024 |
| Entity Registrant Name | Tectonic Therapeutic, Inc. |
| Entity Incorporation State Country Code | DE |
| Entity File Number | 001-38537 |
| Entity Tax Identification Number | 81-0710585 |
| Entity Address Address Line 1 | 490 Arsenal Way |
| Entity Address Address Line 2 | Suite 210 |
| Entity Address City Or Town | Watertown |
| Entity Address State Or Province | MA |
| Entity Address Postal Zip Code | 02472 |
| City Area Code | 339 |
| Local Phone Number | 666-3320 |
| Entity Information Former Legal Or Registered Name | AVROBIO, Inc. |
| Written Communications | false |
| Soliciting Material | false |
| Pre Commencement Tender Offer | false |
| Pre Commencement Issuer Tender Offer | false |
| Security 12b Title | Common Stock, $0.0001 par value per share |
| Trading Symbol | TECX |
| Security Exchange Name | NASDAQ |
| Entity Emerging Growth Company | false |
| Current Fiscal Year End Date | --12-31 |
| Amendment Flag | false |
| Entity Central Index Key | 0001681087 |
| Former Address [Member] | |
| Document And Entity Information [Line Items] | |
| Entity Address Address Line 1 | One Broadway |
| Entity Address Address Line 2 | 14th Floor |
| Entity Address City Or Town | Cambridge |
| Entity Address State Or Province | MA |
| Entity Address Postal Zip Code | 02142 |
