refactor: move render logic to it's own module; add build script

src/render/index.ts

@@ -0,0 +1,67 @@
+import type { AsyncIterableStream, TextStreamPart, ToolSet } from "ai";
+
+const moveCursor = (x: number, y: number) =>
+  new Promise<void>((resolve) => process.stdout.moveCursor(x, y, resolve));
+const clearScreenDown = () =>
+  new Promise<void>((resolve) => process.stdout.clearScreenDown(resolve));
+
+export async function renderStream(
+  stream: AsyncIterableStream<TextStreamPart<ToolSet>>,
+) {
+  let lineCount = 0;
+  let charsSinceNL = 0;
+  const [numColumns, numRows] = process.stdout.getWindowSize();
+
+  for await (const part of stream) {
+    if (part.type === "reasoning-start") {
+      process.stdout.write("\u001b[2m\n");
+    } else if (part.type === "reasoning-delta") {
+      process.stdout.write(part.text);
+
+      charsSinceNL += part.text.length;
+      if (part.text.includes("\n")) {
+        lineCount += part.text.match(/\n/g)?.length ?? 1;
+        charsSinceNL = 0;
+      } else if (charsSinceNL >= numColumns) {
+        lineCount++;
+        charsSinceNL = charsSinceNL - numColumns;
+      }
+
+      if (lineCount >= numRows / 2) {
+        await moveCursor(0, -lineCount);
+        await clearScreenDown();
+        lineCount = 0;
+        charsSinceNL = 0;
+      }
+    } else if (part.type === "reasoning-end") {
+      process.stdout.write("\n\u001b[22m");
+      await moveCursor(0, -lineCount - 2);
+      await clearScreenDown();
+      lineCount = 0;
+      charsSinceNL = 0;
+    } else if (part.type === "text-start") {
+      process.stdout.write("\n");
+    } else if (part.type === "text-delta") {
+      process.stdout.write(part.text);
+
+      charsSinceNL += part.text.length;
+      if (part.text.includes("\n")) {
+        lineCount += part.text.match(/\n/g)?.length ?? 1;
+        charsSinceNL = 0;
+      } else if (charsSinceNL >= numColumns) {
+        lineCount++;
+        charsSinceNL = charsSinceNL - numColumns;
+      }
+
+      if (lineCount >= numRows / 2) {
+        await moveCursor(0, -lineCount);
+        await clearScreenDown();
+        lineCount = 0;
+        charsSinceNL = 0;
+      }
+    } else if (part.type === "text-end") {
+      await moveCursor(0, -lineCount - 1);
+      await clearScreenDown();
+    }
+  }
+}