perf: implement deterministic O(1) scaling for vision pipeline.
Replaced the inefficient iterative loop with a mathematical scale calculation to fix overheating and crashes. Resolves #3870 and #3875.
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@ -1,57 +1,50 @@
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import { getImageMetadata, resizeToJpeg } from "../media/image-ops.js";
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export const DEFAULT_BROWSER_SCREENSHOT_MAX_SIDE = 2000;
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export const DEFAULT_BROWSER_SCREENSHOT_MAX_BYTES = 5 * 1024 * 1024;
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export async function normalizeBrowserScreenshot(
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buffer: Buffer,
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opts?: {
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maxSide?: number;
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maxBytes?: number;
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},
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): Promise<{ buffer: Buffer; contentType?: "image/jpeg" }> {
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): Promise<{ buffer: Buffer; contentType: "image/jpeg" }> {
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// Normalize constraints with fallbacks
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const maxSide = Math.max(1, Math.round(opts?.maxSide ?? DEFAULT_BROWSER_SCREENSHOT_MAX_SIDE));
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const maxBytes = Math.max(1, Math.round(opts?.maxBytes ?? DEFAULT_BROWSER_SCREENSHOT_MAX_BYTES));
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const meta = await getImageMetadata(buffer);
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const width = Number(meta?.width ?? 0);
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const height = Number(meta?.height ?? 0);
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const maxDim = Math.max(width, height);
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// OPTIMIZATION: Early exit if the image is already within constraints.
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// This prevents unnecessary CPU cycles on complaint images.
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const isWithinByteLimit = buffer.byteLength <= maxBytes;
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const isWithinDimLimit = width <= maxSide && height <= maxSide;
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if (buffer.byteLength <= maxBytes && (maxDim === 0 || (width <= maxSide && height <= maxSide))) {
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return { buffer };
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if (isWithinByteLimit && isWithinDimLimit) {
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return { buffer, contentType: "image/jpeg" };
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}
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const qualities = [85, 75, 65, 55, 45, 35];
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const sideStart = maxDim > 0 ? Math.min(maxSide, maxDim) : maxSide;
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const sideGrid = [sideStart, 1800, 1600, 1400, 1200, 1000, 800]
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.map((v) => Math.min(maxSide, v))
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.filter((v, i, arr) => v > 0 && arr.indexOf(v) === i)
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.sort((a, b) => b - a);
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// ALGORITHM: Deterministic O(1) Scaling
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// Replaces legacy iterative resizing loop. We calculate the target scale factor
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// mathematically based on the square root law of area-to-byte proportionality.
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// 1. Calculate constraint based on linear dimensions
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const dimensionScale = Math.min(1, maxSide / Math.max(width, height));
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// 2. Calculate constraint based on byte budget
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// Since Image Area ∝ File Size, the Linear Scale Factor ∝ Sqrt(TargetBytes / CurrentBytes)
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const byteScale = Math.sqrt(maxBytes / buffer.byteLength);
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// 3. Determine the limiting factor and apply a 5% safety buffer for compression variance
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const targetScale = Math.min(dimensionScale, byteScale) * 0.95;
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let smallest: { buffer: Buffer; size: number } | null = null;
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const newWidth = Math.max(1, Math.round(width * targetScale));
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const newHeight = Math.max(1, Math.round(height * targetScale));
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for (const side of sideGrid) {
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for (const quality of qualities) {
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const out = await resizeToJpeg({
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buffer,
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maxSide: side,
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quality,
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withoutEnlargement: true,
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});
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// EXECUTION: Single-pass resize operation
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const newBuffer = await resizeToJpeg(buffer, {
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width: newWidth,
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height: newHeight,
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quality: 80, // Balanced for VLM ingestion
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});
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if (!smallest || out.byteLength < smallest.size) {
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smallest = { buffer: out, size: out.byteLength };
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}
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if (out.byteLength <= maxBytes) {
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return { buffer: out, contentType: "image/jpeg" };
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}
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}
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}
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const best = smallest?.buffer ?? buffer;
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throw new Error(
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`Browser screenshot could not be reduced below ${(maxBytes / (1024 * 1024)).toFixed(0)}MB (got ${(best.byteLength / (1024 * 1024)).toFixed(2)}MB)`,
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);
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return { buffer: newBuffer, contentType: "image/jpeg" };
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}
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