fix: allow SVG files in the convert tool

SVG files were rejected by the convert endpoint because
validateImageBuffer only recognized raster magic bytes. This adds
text-based SVG detection, sanitization in the tool factory, and
proper Sharp density handling so SVG-to-raster conversion works
through the standard convert route.

apps/api/src/lib/file-validation.ts

@@ -1,8 +1,18 @@
 import sharp from "sharp";
 import { env } from "../config.js";
+import { isSvgBuffer } from "./svg-sanitize.js";
 
 /** Formats we accept as input. */
-const SUPPORTED_INPUT_FORMATS = new Set(["jpeg", "png", "webp", "gif", "tiff", "bmp", "avif"]);
+const SUPPORTED_INPUT_FORMATS = new Set([
+  "jpeg",
+  "png",
+  "webp",
+  "gif",
+  "tiff",
+  "bmp",
+  "avif",
+  "svg",
+]);
 
 interface MagicEntry {
   bytes: number[];
@@ -56,8 +66,8 @@ export async function validateImageBuffer(
     return { valid: false, reason: "File contains no image data" };
   }
 
-  // 2. Magic byte detection
-  const detectedFormat = detectMagicBytes(buffer);
+  // 2. Format detection (magic bytes for raster, text check for SVG)
+  const detectedFormat = detectMagicBytes(buffer) || (isSvgBuffer(buffer) ? "svg" : null);
   if (!detectedFormat) {
     return { valid: false, reason: "Unrecognized image format" };
   }
@@ -72,7 +82,8 @@ export async function validateImageBuffer(
 
   // 4. Dimensions check via sharp metadata
   try {
-    const metadata = await sharp(buffer).metadata();
+    const sharpOpts = detectedFormat === "svg" ? { density: 72 } : undefined;
+    const metadata = await sharp(buffer, sharpOpts).metadata();
     const width = metadata.width ?? 0;
     const height = metadata.height ?? 0;
     const megapixels = (width * height) / 1_000_000;

apps/api/src/lib/image-worker.ts

@@ -13,6 +13,7 @@ export interface WorkerInput {
   inputBuffer: Buffer;
   settings: unknown;
   filename: string;
+  inputFormat?: string;
 }
 
 export interface WorkerOutput {
@@ -50,7 +51,8 @@ export default async function processInWorker(input: WorkerInput): Promise<Worke
     throw new Error(`Tool "${input.toolId}" not found in worker registry`);
   }
 
-  const oriented = await autoOrient(Buffer.from(input.inputBuffer));
+  const buf = Buffer.from(input.inputBuffer);
+  const oriented = input.inputFormat === "svg" ? buf : await autoOrient(buf);
   const result = await config.process(oriented, input.settings, input.filename);
 
   return {

apps/api/src/lib/svg-sanitize.ts

@@ -0,0 +1,45 @@
+const MAX_SVG_SIZE = 10 * 1024 * 1024; // 10MB
+
+/**
+ * Sanitize an SVG buffer to prevent XXE, SSRF, and script injection.
+ * Throws if the SVG exceeds the maximum allowed size.
+ */
+export function sanitizeSvg(buffer: Buffer): Buffer {
+  if (buffer.length > MAX_SVG_SIZE) {
+    throw new Error(`SVG exceeds maximum size of ${MAX_SVG_SIZE / 1024 / 1024}MB`);
+  }
+  let svg = buffer.toString("utf-8");
+  // Remove DOCTYPE (XXE prevention, including internal subsets)
+  svg = svg.replace(/<!DOCTYPE[^>[]*(?:\[[^\]]*\])?>/gi, "");
+  // Remove XML processing instructions except <?xml version...?>
+  svg = svg.replace(/<\?(?!xml\s)[^?]*\?>/gi, "");
+  // Remove XInclude elements and namespace declarations
+  svg = svg.replace(/<[^>]*xi:include[^>]*\/?>/gi, "");
+  svg = svg.replace(/xmlns:xi\s*=\s*["'][^"']*["']/gi, "");
+  // Remove script tags
+  svg = svg.replace(/<script[\s\S]*?<\/script>/gi, "");
+  // Remove foreignObject elements (can embed arbitrary HTML)
+  svg = svg.replace(/<foreignObject[\s\S]*?<\/foreignObject>/gi, "");
+  svg = svg.replace(/<foreignObject[^>]*\/>/gi, "");
+  // Remove event handlers (onload, onclick, onerror, etc.)
+  svg = svg.replace(/\bon\w+\s*=/gi, "data-removed=");
+  // Block dangerous URI schemes in href attributes
+  svg = svg.replace(/xlink:href\s*=\s*["']https?:\/\//gi, 'xlink:href="data:,');
+  svg = svg.replace(/href\s*=\s*["']https?:\/\//gi, 'href="data:,');
+  svg = svg.replace(/href\s*=\s*["']javascript:/gi, 'href="data:,');
+  svg = svg.replace(/href\s*=\s*["']data:text\/html/gi, 'href="data:,');
+  svg = svg.replace(/href\s*=\s*["']file:/gi, 'href="data:,');
+  // Block use elements referencing external resources
+  svg = svg.replace(/url\s*\(\s*["']?https?:\/\//gi, 'url("data:,');
+  svg = svg.replace(/url\s*\(\s*["']?file:/gi, 'url("data:,');
+  return Buffer.from(svg, "utf-8");
+}
+
+/**
+ * Check whether a buffer looks like SVG content.
+ * Examines the first 4KB for an <svg tag.
+ */
+export function isSvgBuffer(buffer: Buffer): boolean {
+  const head = buffer.subarray(0, 4096).toString("utf-8").trim();
+  return head.startsWith("<svg") || (head.startsWith("<?xml") && head.includes("<svg"));
+}

apps/api/src/routes/tool-factory.ts

@@ -10,6 +10,7 @@ import { autoOrient } from "../lib/auto-orient.js";
 import { validateImageBuffer } from "../lib/file-validation.js";
 import { sanitizeFilename } from "../lib/filename.js";
 import type { WorkerInput, WorkerOutput } from "../lib/image-worker.js";
+import { sanitizeSvg } from "../lib/svg-sanitize.js";
 import { getWorkerPool } from "../lib/worker-pool.js";
 import { createWorkspace } from "../lib/workspace.js";
 
@@ -144,6 +145,18 @@ export function createToolRoute<T>(app: FastifyInstance, config: ToolRouteConfig
         return reply.status(400).send({ error: `Invalid image: ${validation.reason}` });
       }
 
+      // Sanitize SVG input to prevent XXE, SSRF, and script injection
+      const isSvg = validation.format === "svg";
+      if (isSvg) {
+        try {
+          fileBuffer = sanitizeSvg(fileBuffer);
+        } catch (err) {
+          return reply.status(400).send({
+            error: err instanceof Error ? err.message : "Invalid SVG",
+          });
+        }
+      }
+
       // Parse and validate settings
       let settings: T;
       try {
@@ -179,6 +192,7 @@ export function createToolRoute<T>(app: FastifyInstance, config: ToolRouteConfig
               inputBuffer: fileBuffer,
               settings,
               filename,
+              inputFormat: validation.format,
             };
             const workerResult: WorkerOutput = await pool.run(workerInput);
             result = {
@@ -192,12 +206,12 @@ export function createToolRoute<T>(app: FastifyInstance, config: ToolRouteConfig
               { workerErr, toolId: config.toolId },
               "Worker processing failed, falling back to main thread",
             );
-            const processBuffer = await autoOrient(fileBuffer);
+            const processBuffer = isSvg ? fileBuffer : await autoOrient(fileBuffer);
             result = await config.process(processBuffer, settings, filename);
           }
         } else {
           // AI tools: always main thread (they use Python bridge)
-          const processBuffer = await autoOrient(fileBuffer);
+          const processBuffer = isSvg ? fileBuffer : await autoOrient(fileBuffer);
           result = await config.process(processBuffer, settings, filename);
         }
 

apps/api/src/routes/tools/convert.ts

@@ -3,6 +3,7 @@ import { convert } from "@stirling-image/image-engine";
 import type { FastifyInstance } from "fastify";
 import sharp from "sharp";
 import { z } from "zod";
+import { isSvgBuffer } from "../../lib/svg-sanitize.js";
 import { createToolRoute } from "../tool-factory.js";
 
 const FORMAT_CONTENT_TYPES: Record<string, string> = {
@@ -24,7 +25,8 @@ export function registerConvert(app: FastifyInstance) {
     toolId: "convert",
     settingsSchema,
     process: async (inputBuffer, settings, filename) => {
-      const image = sharp(inputBuffer);
+      const sharpOpts = isSvgBuffer(inputBuffer) ? { density: 300 } : undefined;
+      const image = sharp(inputBuffer, sharpOpts);
       const result = await convert(image, settings);
       const buffer = await result.toBuffer();
 

apps/api/src/routes/tools/svg-to-raster.ts

@@ -4,6 +4,7 @@ import { basename, join } from "node:path";
 import type { FastifyInstance } from "fastify";
 import sharp from "sharp";
 import { z } from "zod";
+import { sanitizeSvg } from "../../lib/svg-sanitize.js";
 import { createWorkspace } from "../../lib/workspace.js";
 
 const settingsSchema = z.object({
@@ -16,39 +17,6 @@ const settingsSchema = z.object({
   outputFormat: z.enum(["png", "jpg", "webp"]).default("png"),
 });
 
-const MAX_SVG_SIZE = 10 * 1024 * 1024; // 10MB
-
-function sanitizeSvg(buffer: Buffer): Buffer {
-  if (buffer.length > MAX_SVG_SIZE) {
-    throw new Error(`SVG exceeds maximum size of ${MAX_SVG_SIZE / 1024 / 1024}MB`);
-  }
-  let svg = buffer.toString("utf-8");
-  // Remove DOCTYPE (XXE prevention, including internal subsets)
-  svg = svg.replace(/<!DOCTYPE[^>[]*(?:\[[^\]]*\])?>/gi, "");
-  // Remove XML processing instructions except <?xml version...?>
-  svg = svg.replace(/<\?(?!xml\s)[^?]*\?>/gi, "");
-  // Remove XInclude elements and namespace declarations
-  svg = svg.replace(/<[^>]*xi:include[^>]*\/?>/gi, "");
-  svg = svg.replace(/xmlns:xi\s*=\s*["'][^"']*["']/gi, "");
-  // Remove script tags
-  svg = svg.replace(/<script[\s\S]*?<\/script>/gi, "");
-  // Remove foreignObject elements (can embed arbitrary HTML)
-  svg = svg.replace(/<foreignObject[\s\S]*?<\/foreignObject>/gi, "");
-  svg = svg.replace(/<foreignObject[^>]*\/>/gi, "");
-  // Remove event handlers (onload, onclick, onerror, etc.)
-  svg = svg.replace(/\bon\w+\s*=/gi, "data-removed=");
-  // Block dangerous URI schemes in href attributes
-  svg = svg.replace(/xlink:href\s*=\s*["']https?:\/\//gi, 'xlink:href="data:,');
-  svg = svg.replace(/href\s*=\s*["']https?:\/\//gi, 'href="data:,');
-  svg = svg.replace(/href\s*=\s*["']javascript:/gi, 'href="data:,');
-  svg = svg.replace(/href\s*=\s*["']data:text\/html/gi, 'href="data:,');
-  svg = svg.replace(/href\s*=\s*["']file:/gi, 'href="data:,');
-  // Block use elements referencing external resources
-  svg = svg.replace(/url\s*\(\s*["']?https?:\/\//gi, 'url("data:,');
-  svg = svg.replace(/url\s*\(\s*["']?file:/gi, 'url("data:,');
-  return Buffer.from(svg, "utf-8");
-}
-
 /**
  * SVG to raster conversion.
  * Custom route since input is SVG (not validated as image by magic bytes).