feat(image-pipeline): add backend capability and fallback diagnostics

lib/image-pipeline/backend/capabilities.ts

@@ -0,0 +1,93 @@
+export type BackendCapabilities = {
+  webgl: boolean;
+  wasmSimd: boolean;
+  offscreenCanvas: boolean;
+};
+
+type CapabilityProbes = {
+  probeWebgl: () => boolean;
+  probeWasmSimd: () => boolean;
+  probeOffscreenCanvas: () => boolean;
+};
+
+const WASM_SIMD_PROBE_MODULE = new Uint8Array([
+  0x00,
+  0x61,
+  0x73,
+  0x6d,
+  0x01,
+  0x00,
+  0x00,
+  0x00,
+  0x01,
+  0x05,
+  0x01,
+  0x60,
+  0x00,
+  0x01,
+  0x7b,
+  0x03,
+  0x02,
+  0x01,
+  0x00,
+  0x0a,
+  0x0a,
+  0x01,
+  0x08,
+  0x00,
+  0x41,
+  0x00,
+  0xfd,
+  0x0f,
+  0x0b,
+]);
+
+function probeOffscreenCanvasAvailability(): boolean {
+  return typeof OffscreenCanvas !== "undefined";
+}
+
+function probeWebglAvailability(): boolean {
+  try {
+    if (typeof document !== "undefined") {
+      const canvas = document.createElement("canvas");
+      const context = canvas.getContext("webgl2") ?? canvas.getContext("webgl");
+      if (context) {
+        return true;
+      }
+    }
+
+    if (typeof OffscreenCanvas !== "undefined") {
+      const offscreenCanvas = new OffscreenCanvas(1, 1);
+      const context = offscreenCanvas.getContext("webgl2") ?? offscreenCanvas.getContext("webgl");
+      return Boolean(context);
+    }
+
+    return false;
+  } catch {
+    return false;
+  }
+}
+
+function probeWasmSimdAvailability(): boolean {
+  if (typeof WebAssembly === "undefined" || typeof WebAssembly.validate !== "function") {
+    return false;
+  }
+
+  try {
+    return WebAssembly.validate(WASM_SIMD_PROBE_MODULE);
+  } catch {
+    return false;
+  }
+}
+
+export function detectBackendCapabilities(probes?: Partial<CapabilityProbes>): BackendCapabilities {
+  const probeWebgl = probes?.probeWebgl ?? probeWebglAvailability;
+  const probeWasmSimd = probes?.probeWasmSimd ?? probeWasmSimdAvailability;
+  const probeOffscreenCanvas = probes?.probeOffscreenCanvas ?? probeOffscreenCanvasAvailability;
+
+  return {
+    webgl: probeWebgl(),
+    wasmSimd: probeWasmSimd(),
+    offscreenCanvas: probeOffscreenCanvas(),
+  };
+}