Reduce VisionKit scan memory by streaming page processing

[Codex]

Lower-end iPhones were restarting the webview due to VNDocumentCameraViewController memory spikes during multi-page scans.

• Streamed processing: process each scanned page individually with autoreleasepool, avoiding retention of all images simultaneously.
• VNDocumentCameraScan path: new finishScan(with scan:) processes VisionKit scans page-by-page via a lightweight provider.
• Simulator path: reuses the same streaming pipeline for sample images.
• Limits respected: page count capped up front via limitedPageCount; response generation unchanged but now per-page.

private func finishScan(with scan: VNDocumentCameraScan) {
    processImages(pageCount: limitedPageCount(total: scan.pageCount)) { index in
        scan.imageOfPage(at: index)
    }
}

private func makeResults(pageCount: Int, imageProvider: @escaping (Int) -> UIImage) throws -> [String] {
    var results: [String] = []
    for index in 0 ..< pageCount {
        let result = try autoreleasepool {
            try process(image: imageProvider(index), at: index)
        }
        results.append(result)
    }
    return results
}

[chatgpt-codex-connector]

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[chatgpt-codex-connector]

Route VisionKit scans through the streaming processor

The new finishScan(with scan: VNDocumentCameraScan) path is never used, so the real-device VisionKit flow still materializes all pages first in didFinishWith scan ((0..<scan.pageCount).map(...)) and then calls the [UIImage] overload. That keeps the original peak-memory behavior this commit is trying to remove, so multi-page scans on low-memory devices can still trigger webview/process restarts. The delegate should call the VNDocumentCameraScan overload directly so pages are processed one-by-one.

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[riderx]

@copilot fix the comment and mark them resolve

[Copilot]

@copilot fix the comment and mark them resolve

Fixed in d5b5d12 — the VisionKit delegate now calls finishScan(with: scan) directly instead of materializing all page images first, so the streaming processor is used on real-device scans as intended.