fix(labs): say when a scanned PDF was read from its first pages only

A PDF longer than the pages a scan renders was read from its first ten
pages, and the cut was recorded only in the wide event. The person checking
the extracted rows had no way to know that values on later pages were never
read.

The rasterizer now returns the PDF's page count, the extract response
carries pageCoverage { read, total } when the cap applied, and the review
screen says how many of the pages were read.

src/app/api/labs/ocr/extract/__tests__/route.test.ts

@@ -229,11 +229,15 @@ describe("POST /api/labs/ocr/extract — vision PDF rasterization", () => {
     vi.mocked(rasterizePdf).mockResolvedValue({
       ok: true,
       images: [{ mediaType: "image/jpeg", dataBase64: "cGFnZQ==" }],
+      pageCount: 1,
     });
     vi.mocked(runOcrExtraction).mockResolvedValue({ rows: [] } as never);
 
     const res = await POST(pdfReq());
     expect(res.status).toBe(200);
+    // The whole PDF was read: no coverage note on the response.
+    const whole = (await res.json()) as { data: Record<string, unknown> };
+    expect(whole.data).not.toHaveProperty("pageCoverage");
     expect(rasterizePdf).toHaveBeenCalledOnce();
     // The rendered page images flow through as `input_image`s; no native PDF
     // document block is sent for a non-Anthropic provider.
@@ -245,6 +249,26 @@ describe("POST /api/labs/ocr/extract — vision PDF rasterization", () => {
     );
   });
 
+  it("says on the response when only the first pages of a long PDF were read", async () => {
+    const tenPages = Array.from({ length: 10 }, () => ({
+      mediaType: "image/jpeg" as const,
+      dataBase64: "cGFnZQ==",
+    }));
+    vi.mocked(rasterizePdf).mockResolvedValue({
+      ok: true,
+      images: tenPages,
+      pageCount: 23,
+    });
+    vi.mocked(runOcrExtraction).mockResolvedValue({ rows: [] } as never);
+
+    const res = await POST(pdfReq());
+    expect(res.status).toBe(200);
+    const body = (await res.json()) as {
+      data: { pageCoverage?: { read: number; total: number } };
+    };
+    expect(body.data.pageCoverage).toEqual({ read: 10, total: 23 });
+  });
+
   it("hands the slot back when the upload is not an image or PDF", async () => {
     const form = new FormData();
     form.append(

src/app/api/labs/ocr/extract/route.ts

@@ -374,6 +374,7 @@ async function handleVisionExtract(
       dataBase64: string;
     }[];
     let documents: { mediaType: "application/pdf"; dataBase64: string }[];
+    let pageCoverage: { read: number; total: number } | undefined;
 
     if (mime === "application/pdf") {
       if (pick.pdfSupported) {
@@ -404,6 +405,20 @@ async function handleVisionExtract(
         }
         images = raster.images;
         documents = [];
+        // A PDF longer than the page cap is read from its first pages only.
+        // That used to live in the wide event alone; the person reviewing the
+        // rows is the one who needs to know the rest of the report was not
+        // read.
+        if (raster.pageCount > raster.images.length) {
+          pageCoverage = {
+            read: raster.images.length,
+            total: raster.pageCount,
+          };
+          annotate({
+            action: { name: "labs.ocr.pagesCapped" },
+            meta: { read: raster.images.length, total: raster.pageCount },
+          });
+        }
       }
     } else {
       images = [{ mediaType: mime, dataBase64: buffer.toString("base64") }];
@@ -431,7 +446,7 @@ async function handleVisionExtract(
         0,
         { servedBy: pick.entry.providerType, reservedOwner: reservation.owner },
       );
-      return apiSuccess(result);
+      return apiSuccess(pageCoverage ? { ...result, pageCoverage } : result);
     } catch (err) {
       // Provider/extraction failure — the call may still have burned tokens, so
       // reconcile against the reserved estimate rather than refunding in full.