feat: dynamic timeouts — scale with image size, respect PROCESSING_TIMEOUT_S

Create timeout.ts utility for dynamic timeout computation.
Replace hardcoded timeouts across the stack:
- tool-factory worker: 30s → dynamic based on megapixels
- Python bridge default: 300s → 600s (or env override)
- background-removal: fixed → dynamic based on image size
- OCR: fixed 600s → dynamic based on image size
- seam-carving: 120s → dynamic based on image size
- ExifTool: 30s → 60s
- HEIC converter: 30s → 120s
- SQLite busy_timeout: 5s → 10s

packages/ai/src/background-removal.ts

@@ -2,6 +2,7 @@ import { randomUUID } from "node:crypto";
 import { readFile, unlink, writeFile } from "node:fs/promises";
 import { tmpdir } from "node:os";
 import { join } from "node:path";
+import sharp from "sharp";
 import { type ProgressCallback, parseStdoutJson, runPythonWithProgress } from "./bridge.js";
 
 export interface RemoveBackgroundOptions {
@@ -21,8 +22,10 @@ export async function removeBackground(
 
   await writeFile(inputPath, inputBuffer);
   try {
-    // BiRefNet models need longer timeout (up to 10 min for first load)
-    const timeout = options.model?.startsWith("birefnet") ? 600000 : 300000;
+    const meta = await sharp(inputBuffer).metadata();
+    const megapixels = ((meta.width ?? 0) * (meta.height ?? 0)) / 1_000_000;
+    const baseTimeout = options.model?.startsWith("birefnet") ? 600000 : 300000;
+    const timeout = Math.max(baseTimeout, megapixels * 30 * 1000);
     const { stdout } = await runPythonWithProgress(
       "remove_bg.py",
       [inputPath, outputPath, JSON.stringify(options)],

packages/ai/src/bridge.ts

@@ -218,7 +218,11 @@ function dispatcherRun(
   if (!proc || !proc.stdin || !dispatcherReady) return null;
 
   const id = randomUUID();
-  const timeout = options.timeout ?? 300000;
+  const timeout =
+    options.timeout ??
+    (process.env.PROCESSING_TIMEOUT_S && parseInt(process.env.PROCESSING_TIMEOUT_S, 10) > 0
+      ? parseInt(process.env.PROCESSING_TIMEOUT_S, 10) * 1000
+      : 600000);
 
   return new Promise((resolvePromise, rejectPromise) => {
     const timer = setTimeout(() => {
@@ -278,7 +282,11 @@ function runPythonPerRequest(
   } = {},
 ): Promise<{ stdout: string; stderr: string }> {
   const scriptPath = resolve(PYTHON_DIR, scriptName);
-  const timeout = options.timeout ?? 300000;
+  const timeout =
+    options.timeout ??
+    (process.env.PROCESSING_TIMEOUT_S && parseInt(process.env.PROCESSING_TIMEOUT_S, 10) > 0
+      ? parseInt(process.env.PROCESSING_TIMEOUT_S, 10) * 1000
+      : 600000);
 
   return new Promise((resolvePromise, rejectPromise) => {
     const trySpawn = (pythonBin: string, isFallback: boolean) => {

packages/ai/src/ocr.ts

@@ -31,9 +31,13 @@ export async function extractText(
   const pngBuffer = await sharp(inputBuffer).png().toBuffer();
   await writeFile(inputPath, pngBuffer);
 
+  const meta = await sharp(inputBuffer).metadata();
+  const megapixels = ((meta.width ?? 0) * (meta.height ?? 0)) / 1_000_000;
+  const timeout = Math.max(600_000, megapixels * 30 * 1000);
+
   const { stdout } = await runPythonWithProgress("ocr.py", [inputPath, JSON.stringify(options)], {
     onProgress,
-    timeout: 600_000, // 10 min timeout for VLM on CPU
+    timeout,
   });
 
   const result = parseStdoutJson(stdout);

packages/ai/src/seam-carving.ts

@@ -122,7 +122,9 @@ export async function seamCarve(
     if (options.blurRadius !== undefined) args.push("-blur", String(options.blurRadius));
     if (options.sobelThreshold !== undefined) args.push("-sobel", String(options.sobelThreshold));
 
-    await execFileAsync(cairePath, args, { timeout: 120_000 });
+    const megapixels = (origWidth * origHeight) / 1_000_000;
+    const timeoutMs = Math.max(120_000, megapixels * 10 * 1000);
+    await execFileAsync(cairePath, args, { timeout: timeoutMs });
 
     const buffer = await readFile(outputPath);
     const outMeta = await sharp(buffer).metadata();