feat(generators): byte-identical snapshot machinery + realtime snapshot

turbo/generators/lib/snapshot.test.ts

@@ -0,0 +1,19 @@
+import { describe, it, expect } from "vitest";
+import { mkdtempSync, mkdirSync, writeFileSync } from "node:fs";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { computeSnapshot } from "./snapshot";
+
+describe("computeSnapshot", () => {
+  it("returns sorted file paths + sha256 hashes", () => {
+    const tmp = mkdtempSync(join(tmpdir(), "snapshot-"));
+    mkdirSync(join(tmp, "src"));
+    writeFileSync(join(tmp, "package.json"), `{ "name": "x" }\n`);
+    writeFileSync(join(tmp, "src", "index.ts"), `export {};\n`);
+    const snap = computeSnapshot(tmp);
+    expect(snap).toEqual([
+      { path: "package.json", sha256: expect.any(String) },
+      { path: "src/index.ts", sha256: expect.any(String) },
+    ]);
+  });
+});

turbo/generators/lib/snapshot.ts

@@ -0,0 +1,33 @@
+import { readdirSync, readFileSync, statSync } from "node:fs";
+import { createHash } from "node:crypto";
+import { join, relative } from "node:path";
+
+export type SnapshotEntry = { path: string; sha256: string };
+
+/**
+ * Recursively collect all files under root, sorted by relative path, with
+ * sha256 of post-normalized contents (LF line endings, single trailing
+ * newline). Used by the byte-identical reconstruction test.
+ */
+export function computeSnapshot(root: string): SnapshotEntry[] {
+  const out: SnapshotEntry[] = [];
+  walk(root, root, out);
+  out.sort((a, b) => (a.path < b.path ? -1 : a.path > b.path ? 1 : 0));
+  return out;
+}
+
+function walk(root: string, dir: string, out: SnapshotEntry[]): void {
+  for (const name of readdirSync(dir)) {
+    const full = join(dir, name);
+    const stat = statSync(full);
+    if (stat.isDirectory()) {
+      if (name === "node_modules" || name === ".turbo") continue;
+      walk(root, full, out);
+    } else if (stat.isFile()) {
+      const raw = readFileSync(full, "utf8");
+      const normalized = raw.replace(/\r\n/g, "\n").replace(/\n*$/, "\n");
+      const sha = createHash("sha256").update(normalized).digest("hex");
+      out.push({ path: relative(root, full).replace(/\\/g, "/"), sha256: sha });
+    }
+  }
+}