feat(ocr): transformation layer on ocrRegistry (Mistral shape canonical)

open-sse/config/ocrRegistry.ts

@@ -16,6 +16,7 @@ export interface OcrProvider {
   authType: string;
   authHeader: string;
   models: OcrModel[];
+  transformation?: OcrTransformation;
 }
 
 export interface ParsedOcrModel {
@@ -23,6 +24,44 @@ export interface ParsedOcrModel {
   model: string | null;
 }
 
+export interface OcrResponseShape {
+  pages: Array<{ index: number; markdown: string }>;
+  model: string;
+  usage_info?: Record<string, unknown>;
+}
+
+export interface OcrTransformation {
+  buildRequest(args: {
+    baseUrl: string;
+    token: string;
+    body: Record<string, unknown>;
+    modelId: string;
+  }): { url: string; init: RequestInit };
+  parseResponse(raw: unknown): OcrResponseShape;
+  /** Async providers (Azure DI): return the poll URL from the first response, else null. */
+  pollUrl?(res: Response): string | null;
+}
+
+export const MISTRAL_PASSTHROUGH: OcrTransformation = {
+  buildRequest({ baseUrl, token, body, modelId }) {
+    return {
+      url: baseUrl,
+      init: {
+        method: "POST",
+        headers: { "Content-Type": "application/json", Authorization: `Bearer ${token}` },
+        body: JSON.stringify({ ...body, model: modelId }),
+      },
+    };
+  },
+  parseResponse(raw) {
+    return raw as OcrResponseShape;
+  },
+};
+
+export function getOcrTransformation(providerId: string): OcrTransformation {
+  return OCR_PROVIDERS[providerId]?.transformation ?? MISTRAL_PASSTHROUGH;
+}
+
 export const OCR_PROVIDERS: Record<string, OcrProvider> = {
   mistral: {
     id: "mistral",

tests/unit/ocr-registry-transformations.test.ts

@@ -0,0 +1,28 @@
+import { test } from "node:test";
+import assert from "node:assert/strict";
+import {
+  OCR_PROVIDERS,
+  getOcrTransformation,
+  MISTRAL_PASSTHROUGH,
+} from "../../open-sse/config/ocrRegistry.ts";
+
+test("mistral resolves the passthrough transformation by default", () => {
+  const t = getOcrTransformation("mistral");
+  assert.equal(t, MISTRAL_PASSTHROUGH);
+  const { url, init } = t.buildRequest({
+    baseUrl: OCR_PROVIDERS.mistral.baseUrl,
+    token: "sk-test",
+    body: { document: { type: "image_url", image_url: "https://x/y.png" } },
+    modelId: "mistral-ocr-latest",
+  });
+  assert.equal(url, "https://api.mistral.ai/v1/ocr");
+  assert.equal(init.method, "POST");
+  assert.equal((init.headers as Record<string, string>).Authorization, "Bearer sk-test");
+  const sent = JSON.parse(String(init.body));
+  assert.equal(sent.model, "mistral-ocr-latest");
+});
+
+test("passthrough parseResponse returns the body unchanged (Mistral is the canonical shape)", () => {
+  const raw = { pages: [{ index: 0, markdown: "hello" }], model: "mistral-ocr-latest" };
+  assert.deepEqual(MISTRAL_PASSTHROUGH.parseResponse(raw), raw);
+});