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Stockholders Deficit and Redeemable Convertible Preferred Stock - Schedule of Redeemable Convertible Preferred Stock (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands | Sep. 30, 2025 | Dec. 31, 2024
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Redeemable convertible preferred stock |  |
Class of Stock [Line Items] |  |
Temporary equity, shares authorized (in shares) |  | 51,033
Temporary equity, Shares issued |  | 41,588
Temporary equity, Shares outstanding |  | 41,588
Temporary equity, Carrying value |  | $ 759,582
Series Seed Preferred Stock | Redeemable convertible preferred stock |  |
Class of Stock [Line Items] |  |
Temporary equity, par or stated value per share |  | $ 0.0001
Temporary equity, shares authorized (in shares) |  | 2,023
Temporary equity, Shares issued |  | 2,023
Temporary equity, Shares outstanding |  | 2,023
Temporary equity, Carrying value |  | $ 2,950
Series Seed-1 Preferred Stock | Redeemable convertible preferred stock |  |
Class of Stock [Line Items] |  |
Temporary equity, par or stated value per share |  | $ 0.0001
Temporary equity, shares authorized (in shares) |  | 3,273
Temporary equity, Shares issued |  | 3,273
Temporary equity, Shares outstanding |  | 3,273
Temporary equity, Carrying value |  | $ 204,454
Series A Preferred Stock | Redeemable convertible preferred stock |  |
Class of Stock [Line Items] |  |
Temporary equity, par or stated value per share |  | $ 0.0001
Temporary equity, shares authorized (in shares) |  | 6,005
Temporary equity, Shares issued |  | 6,005
Temporary equity, Shares outstanding |  | 6,005
Temporary equity, Carrying value |  | $ 74,913
Series B Preferred Stock | Redeemable convertible preferred stock |  |
Class of Stock [Line Items] |  |
Temporary equity, par or stated value per share |  | $ 0.0001
Temporary equity, shares authorized (in shares) |  | 5,869
Temporary equity, Shares issued |  | 5,869
Temporary equity, Shares outstanding |  | 5,869
Temporary equity, Carrying value |  | $ 72,096
Series C Preferred Stock | Redeemable convertible preferred stock |  |
Class of Stock [Line Items] |  |
Temporary equity, par or stated value per share |  | $ 0.0001
Temporary equity, shares authorized (in shares) |  | 11,159
Temporary equity, Shares issued |  | 11,159
Temporary equity, Shares outstanding |  | 11,159
Temporary equity, Carrying value |  | $ 213,871
Series M Preferred Stock | Redeemable convertible preferred stock |  |
Class of Stock [Line Items] |  |
Temporary equity, par or stated value per share |  | $ 0.0001
Temporary equity, shares authorized (in shares) |  | 2,812
Temporary equity, Shares issued |  | 2,812
Temporary equity, Shares outstanding |  | 2,812
Temporary equity, Carrying value |  | $ 10,990
Series J Preferred Stock | Redeemable convertible preferred stock |  |
Class of Stock [Line Items] |  |
Temporary equity, par or stated value per share |  | $ 0.0001
Temporary equity, shares authorized (in shares) |  | 922
Temporary equity, Shares issued |  | 0
Temporary equity, Shares outstanding |  | 0
Temporary equity, Carrying value |  | $ 0
Series D-1 Preferred Stock | Redeemable convertible preferred stock |  |
Class of Stock [Line Items] |  |
Temporary equity, par or stated value per share |  | $ 0.0001
Temporary equity, shares authorized (in shares) |  | 17,729
Temporary equity, Shares issued |  | 10,447
Temporary equity, Shares outstanding |  | 10,447
Temporary equity, Carrying value |  | $ 180,308
Series D-2 Preferred Stock | Redeemable convertible preferred stock |  |
Class of Stock [Line Items] |  |
Temporary equity, par or stated value per share |  | $ 0.0001
Temporary equity, shares authorized (in shares) |  | 1,241
Temporary equity, Shares issued |  | 0
Temporary equity, Shares outstanding |  | 0
Temporary equity, Carrying value |  | $ 0
Redeemable Convertible Preferred Stock |  |
Class of Stock [Line Items] |  |
Temporary equity, par or stated value per share | $ 0.0001 | $ 0.0001
Temporary equity, shares authorized (in shares) | 100,000 | 51,033
Temporary equity, Shares issued | 0 | 41,588
Temporary equity, Shares outstanding | 0 | 41,588

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