refactor(media): flatten output formatting

Amp-Thread-ID: https://ampcode.com/threads/T-019ff438-3b93-77b8-9828-1d3c586cb127

packages/media-understanding-common/src/format.ts

@@ -1,9 +1,18 @@
 // Media Understanding Common helper module supports format behavior.
 import type { MediaUnderstandingOutput } from "./types.js";
 
+const sectionByKind = {
+  "audio.transcription": { title: "Audio", label: "Transcript" },
+  "image.description": { title: "Image", label: "Description" },
+  "video.description": { title: "Video", label: "Description" },
+} satisfies Record<
+  MediaUnderstandingOutput["kind"],
+  { title: string; label: "Transcript" | "Description" }
+>;
+
 function formatSection(
   title: string,
-  kind: "Transcript" | "Description",
+  label: "Transcript" | "Description",
   text: string,
   userText?: string,
 ): string {
@@ -11,7 +20,7 @@ function formatSection(
   if (userText) {
     lines.push(`User text:\n${userText}`);
   }
-  lines.push(`${kind}:\n${text}`);
+  lines.push(`${label}:\n${text}`);
   return lines.join("\n");
 }
 
@@ -42,32 +51,11 @@ export function formatMediaUnderstandingBody(params: {
     const next = (seen.get(output.kind) ?? 0) + 1;
     seen.set(output.kind, next);
     const suffix = count > 1 ? ` ${next}/${count}` : "";
-    if (output.kind === "audio.transcription") {
-      sections.push(
-        formatSection(
-          `Audio${suffix}`,
-          "Transcript",
-          output.text,
-          outputs.length === 1 ? userText : undefined,
-        ),
-      );
-      continue;
-    }
-    if (output.kind === "image.description") {
-      sections.push(
-        formatSection(
-          `Image${suffix}`,
-          "Description",
-          output.text,
-          outputs.length === 1 ? userText : undefined,
-        ),
-      );
-      continue;
-    }
+    const section = sectionByKind[output.kind];
     sections.push(
       formatSection(
-        `Video${suffix}`,
-        "Description",
+        `${section.title}${suffix}`,
+        section.label,
         output.text,
         outputs.length === 1 ? userText : undefined,
       ),