// playwright/packages/playwright-core/src/server/dom.ts

async setInputFiles(metadata: CallMetadata, params: channels.ElementHandleSetInputFilesParams) {
    const inputFileItems = await prepareFilesForUpload(this._frame, params);
    // ...
}

// playwright/packages/playwright-core/src/server/fileUploadUtils.ts

// Keep in sync with the client.
export const fileUploadSizeLimit = 50 * 1024 * 1024; // 50M 核心限制

async function filesExceedUploadLimit(files: string[]) {
  const sizes = await Promise.all(files.map(async file => (await fs.promises.stat(file)).size));
  return sizes.reduce((total, size) => total + size, 0) >= fileUploadSizeLimit;
}

// ...

if (await filesExceedUploadLimit(localPaths)) // 判断文件是否超过 50MB。
    throw new Error('Cannot transfer files larger than 50Mb to a browser not co-located with the server');

protected async setInputFiles(options: {
        selector: string
        context: BrowserContext,
        filepath: string,
    }): Promise<void> {
        try {
            if (!await file.exists(options.filepath)) {
                throw new Error('setInputFiles not found.');
            }
            const [page] = options.context.pages()
            const filesize = await file.size(options.filepath);
            logger.info('setInputFiles: %s MB', filesize)
            if (filesize < 50) { // skip transfer 50M limit!
                return await page.setInputFiles(options.selector, options.filepath)
            }
            const cdp = await options.context.newCDPSession(page)
            await cdp.send('DOM.enable')
            const {root} = await cdp.send('DOM.getDocument')
            let rootId = root.nodeId

            // shadowRoot (playwright 支持 >> 直接穿透，CDP session 不行)
            if (options.selector.includes(">>")) {
                const selector = options.selector.split(" >> ")
                const {nodeId: hostNodeId} = await cdp.send('DOM.querySelector', {
                    nodeId: rootId,
                    selector: selector[0]
                })
                const shadows = await cdp.send('DOM.describeNode', {
                    nodeId: hostNodeId
                });
                const shadowRootNodeId = shadows.node.shadowRoots?.[0]?.nodeId ?? 0
                if (shadowRootNodeId === 0) {
                    return Promise.reject({status: State.FAILED, message: 'setInputFiles node not found.'})
                }
                rootId = shadowRootNodeId // transform to shadowRoot
                options.selector = selector[1]
                logger.info('setInputFiles: shadowRootsId: %s selector: %s', rootId, options.selector)
            }

            const {nodeId} = await cdp.send('DOM.querySelector', {
                nodeId: rootId,
                selector: options.selector
            })
            await cdp.send('DOM.setFileInputFiles', {
                nodeId,
                files: [options.filepath]
            })
        } catch (reason) {
            throw new Error('setInputFiles failed')
        }
    }