增加语音对话功能

src/modules/lecture/infrastructure/pdf/chunker.ts

@@ -0,0 +1,55 @@
+/** Coarse paragraph chunks from PDFWorker plain text (MinerU MVP fallback). */
+
+export interface TextChunk {
+  id: string;
+  orderIndex: number;
+  text: string;
+}
+
+const MIN_CHUNK_CHARS = 200;
+const MAX_CHUNK_CHARS = 900;
+const MAX_CHUNKS = 40;
+
+export function chunkPaperText(text: string): TextChunk[] {
+  const paragraphs = text
+    .split(/\n\s*\n+/)
+    .map((s) => s.replace(/\s+/g, " ").trim())
+    .filter((s) => s.length > 40);
+
+  const merged: string[] = [];
+  let buffer = "";
+
+  for (const para of paragraphs) {
+    if (
+      buffer &&
+      (buffer.length + para.length > MAX_CHUNK_CHARS ||
+        (buffer.length >= MIN_CHUNK_CHARS && merged.length >= MAX_CHUNKS - 1))
+    ) {
+      merged.push(buffer);
+      buffer = para;
+    } else {
+      buffer = buffer ? `${buffer} ${para}` : para;
+    }
+  }
+  if (buffer) merged.push(buffer);
+
+  if (!merged.length && text.trim()) {
+    merged.push(text.trim().slice(0, MAX_CHUNK_CHARS));
+  }
+
+  return merged.slice(0, MAX_CHUNKS).map((chunkText, orderIndex) => ({
+    id: `p-${orderIndex}`,
+    orderIndex,
+    text: chunkText.slice(0, 2000),
+  }));
+}
+
+/** Compact outline for LLM beats generation. */
+export function formatChunkOutline(chunks: TextChunk[]): string {
+  return chunks
+    .map(
+      (c) =>
+        `[${c.id}] ${c.text.slice(0, 100)}${c.text.length > 100 ? "…" : ""}`,
+    )
+    .join("\n");
+}