fix(cli): exit via process.exitCode so piped stdout flushes completely

packages/cli/src/bin.ts

@@ -1,5 +1,10 @@
 #!/usr/bin/env node
-// [CLI-BIN] Entry point for the typediagram CLI binary.
+// [CLI-BIN] Entry point for the typediagram CLI binary. Sets `process.exitCode`
+// rather than calling `process.exit()`: exit() terminates before Node drains
+// pending stdout writes, silently truncating piped output larger than one
+// synchronous pipe write (issue #48).
 import { main } from "./cli.js";
 
-void main(process.argv.slice(2), process.stdout, process.stderr).then((code) => process.exit(code));
+void main(process.argv.slice(2), process.stdout, process.stderr).then((code) => {
+  process.exitCode = code;
+});

packages/cli/test/bin-flush.e2e.test.ts

@@ -0,0 +1,56 @@
+// [CLI-BIN] Regression for https://github.com/Nimblesite/typeDiagram/issues/48 —
+// the bin must flush ALL piped stdout before exiting. With `process.exit()` in
+// bin.ts, piped output larger than one synchronous pipe write was silently
+// truncated (observed: cut at exactly 8 KB with exit code 0). Black-box:
+// builds the real bin with tsc, then spawns it with stdout as a pipe.
+import { execFile } from "node:child_process";
+import { mkdtemp, writeFile } from "node:fs/promises";
+import { createRequire } from "node:module";
+import { tmpdir } from "node:os";
+import { dirname, join } from "node:path";
+import { fileURLToPath } from "node:url";
+import { promisify } from "node:util";
+import { beforeAll, describe, expect, it } from "vitest";
+
+const run = promisify(execFile);
+const PKG_ROOT = fileURLToPath(new URL("..", import.meta.url));
+const BIN = join(PKG_ROOT, "dist", "bin.js");
+const TSC = join(dirname(createRequire(import.meta.url).resolve("typescript/package.json")), "bin", "tsc");
+
+// Enough types that the Rust emission far exceeds the 64 KB kernel pipe
+// buffer, so a premature exit cannot have flushed the tail synchronously.
+const TYPE_COUNT = 1500;
+
+const bigTdSource = () => {
+  const types = Array.from(
+    { length: TYPE_COUNT },
+    (_, index) =>
+      `  type Generated${String(index)} {\n` +
+      `    name: String\n` +
+      `    labels: List<String>\n` +
+      `    description: String\n` +
+      `  }`
+  );
+  return `typeDiagram\n\n${types.join("\n\n")}\n`;
+};
+
+describe("[CLI-BIN] bin flushes piped stdout completely (issue #48)", () => {
+  let tdPath = "";
+
+  beforeAll(async () => {
+    await run(process.execPath, [TSC, "-p", "tsconfig.build.json"], { cwd: PKG_ROOT });
+    tdPath = join(await mkdtemp(join(tmpdir(), "bin-flush-")), "big.td");
+    await writeFile(tdPath, bigTdSource());
+  }, 120_000);
+
+  it.each([1, 2, 3])("emits every generated type through a pipe (run %i)", async () => {
+    const { stdout, stderr } = await run(process.execPath, [BIN, "--to", "rust", tdPath], {
+      maxBuffer: 16 * 1024 * 1024,
+    });
+    expect(stderr).toBe("");
+    expect(stdout.length).toBeGreaterThan(64 * 1024);
+    expect(stdout).toContain("pub struct Generated0 ");
+    expect(stdout).toContain(`pub struct Generated${String(TYPE_COUNT - 1)} `);
+    expect(stdout.trimEnd().endsWith("}")).toBe(true);
+  });
+});