Upload a local file into a page's file input inside a remote Browserbase session

Documented steps

1. Create a session (POST https://api.browserbase.com/v1/sessions, header X-BB-API-Key) and connect Playwright or Puppeteer to its connectUrl.
2. For the standard case use Playwright's setInputFiles, which streams the file from your machine to the remote browser: Node const input = page.locator("#fileUpload"); await input.setInputFiles("logo.png"); Python file_input.set_input_files("logo.png"). Reference: https://docs.browserbase.com/platform/browser/files/uploads
3. For larger files, stage the file onto the session first via the SDK: await bb.sessions.uploads.create(session.id, { file: fileStream }).
4. Direct API equivalent: POST https://api.browserbase.com/v1/sessions/{id}/uploads with headers X-BB-API-Key and Content-Type: multipart/form-data, and the binary in the form field named file. Reference: https://docs.browserbase.com/reference/api/create-session-uploads
5. Expect HTTP 200 with the body { "message": "string" } - no file id or metadata is returned, so record the filename you sent.
6. CDP-only alternative: call DOM.setFileInputFiles with { files: [remotePath], nodeId: inputNode.nodeId }, where remotePath is a file already staged inside the container at /tmp/.uploads/{fileName}.
7. Do not mix the two path conventions: setInputFiles resolves paths on your local machine, while DOM.setFileInputFiles requires a path that exists inside the remote container.
8. Confirm success by reading the input's value or the application's own upload confirmation in the page, since the uploads endpoint returns no verifiable handle.
9. Wait for the site's upload request to complete (e.g. Playwright's waitForResponse on the upload endpoint) before navigating away.