fix(receipt): carry and write handle PRs with thousands of files; tree receipt fails closed on a failed diff (GST-448)

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

test/ship-receipt-carry-large-diff.test.ts

@@ -0,0 +1,53 @@
+/**
+ * gstack-ship-receipt carry on a PR whose own diff is large (GST-448, harness-evals#147): a results PR that adds thousands
+ * of run-receipt files has a name-only listing and a product diff over the child-process output buffer, so carry refused
+ * with "git could not compute HEAD's product patch-id: git diff … failed" after every base move.
+ */
+import { afterEach, describe, expect, setDefaultTimeout, test } from 'bun:test';
+import * as fs from 'node:fs';
+import * as path from 'node:path';
+import { EXIT } from '../lib/headless-artifacts';
+import { extractReceipt } from '../lib/ship-receipt';
+import { cleanup, commit, makeFixtureRepo, runBin, write, type FixtureRepo } from './helpers/pregate-fixture';
+
+setDefaultTimeout(120_000);
+const repos: FixtureRepo[] = [];
+afterEach(() => { while (repos.length) cleanup(repos.pop()!); });
+const DIR = `results/${'harness-eval-run-receipts-'.repeat(8)}`;
+/** `count` run receipts under a long directory name: about 1.4 MB of paths and 2 MB of diff, past the 1 MB default buffer. */
+const receipts = (count: number, tag: string) => Object.fromEntries(Array.from({ length: count }, (_, i) => [`${DIR}/${tag}-run-${String(i).padStart(5, '0')}.json`, `{"run":${i},"tag":"${tag}","score":0.${i % 10}}\n`]));
+
+describe('carry with a large product diff (GST-448)', () => {
+  // Value: protects=a results PR keeps its receipt across a base move when its own diff is megabytes of added files
+  //   (harness-evals#147 paid ~3h of /ship per base move); fails_when=carry buffers git's name-only listing or the diff in
+  //   a bounded child-process buffer and refuses; seam=none; no_claim=gh pr edit (--body stands in)
+  test('a base merge carries the receipt of a PR that adds 6000 files', () => {
+    const repo = makeFixtureRepo(); repos.push(repo);
+    commit(repo, receipts(6000, 'base'), 'results: 6000 run receipts');
+    const body = path.join(repo.root, 'body.md');
+    const w = runBin(repo, 'gstack-ship-receipt', ['write', '--pr', '9', '--base', 'main', '--version', '1.0.0', '--session-kind', 'unattended', '--body', body]);
+    expect(w.status).toBe(EXIT.ok);
+    const reviewed = extractReceipt(fs.readFileSync(body, 'utf8')).receipt!.product_patch_id;
+    expect(reviewed).toMatch(/^[0-9a-f]{40}$/);
+    repo.git('checkout', '-q', 'main');
+    write(repo.work, 'docs/README.md', '# docs moved on main\n');
+    repo.git('add', '-A'); repo.git('commit', '-qm', 'main moves on'); repo.git('push', '-q', 'origin', 'main');
+    repo.git('checkout', '-q', 'feature');
+    repo.git('merge', '-q', '--no-edit', 'origin/main');
+    const out = runBin(repo, 'gstack-ship-receipt', ['carry', '--body', body, '--base', 'main']);
+    expect([out.status, out.out.split('\n').find(l => l.startsWith('CARRY:')), out.err.split('\n').find(l => l.includes('RECEIPT_CARRY'))]).toEqual([EXIT.ok, expect.stringMatching(/^CARRY: carried/), undefined]);
+    expect(extractReceipt(fs.readFileSync(body, 'utf8')).receipt!.product_patch_id).toBe(reviewed);
+  });
+
+  // Value: protects=negative control: the large-diff path still refuses when the PR's own receipts change after review;
+  //   fails_when=the streamed patch-id reads as unchanged for a changed diff; seam=none; no_claim=none
+  test('one changed receipt in the large diff still refuses the carry', () => {
+    const repo = makeFixtureRepo(); repos.push(repo);
+    commit(repo, receipts(6000, 'base'), 'results: 6000 run receipts');
+    const body = path.join(repo.root, 'body.md');
+    expect(runBin(repo, 'gstack-ship-receipt', ['write', '--pr', '9', '--base', 'main', '--version', '1.0.0', '--session-kind', 'unattended', '--body', body]).status).toBe(EXIT.ok);
+    commit(repo, { [`${DIR}/base-run-00042.json`]: '{"run":42,"tag":"base","score":0.9}\n' }, 'results: rescore run 42');
+    const out = runBin(repo, 'gstack-ship-receipt', ['carry', '--body', body, '--base', 'main']);
+    expect([out.status, out.out.split('\n').find(l => l.startsWith('CARRY:'))]).toEqual([EXIT.refused, 'CARRY: refused (RECEIPT_CARRY_PRODUCT_CHANGED)']);
+  });
+});