bb plugin new scaffolds a plugin that cannot import @get-bb/plugin-sdk/testing: cron-parser is undeclared

[t1mdurden]

Summary

bb plugin new scaffolds a plugin that cannot import @get-bb/plugin-sdk/testing — the backend test harness the bundled bb-plugin-authoring skill tells plugin authors to test with. The first createFakePluginHost test in a fresh scaffold fails to load with Cannot find package 'cron-parser', pointing at a file inside node_modules with nothing in the guide to explain it.

Versions and environment

• bb 0.40.0, desktop app. Also reproduced from source at ad79bbb5ec909524f8f281e62d860c588a86f332.
• macOS 15 (Darwin 25.3.0), arm64.
• Node v20.13.1, npm 10.5.2.

Steps to reproduce

bb plugin new probe
cd bb-plugin-probe
npm install --include=dev
npm install --save-dev vitest
cat > server.test.ts <<'TS'
import { it } from "vitest";
import { createFakePluginHost } from "@get-bb/plugin-sdk/testing";
import plugin from "./server";

it("loads", async () => {
  const { bb } = createFakePluginHost({ pluginId: "probe" });
  await plugin(bb);
});
TS
npx vitest run

Expected vs actual

Actual:

FAIL  server.test.ts [ server.test.ts ]
Error: Cannot find package 'cron-parser' imported from
  .../bb-plugin-probe/node_modules/@get-bb/plugin-sdk/dist/testing/index.js

Expected: the test runs. The scaffold already ships the harness's other peers, so the intent is clearly that it works.

Evidence

The backend harness imports exactly four npm packages — better-sqlite3, cron-parser, hono, zod:

• bb/packages/plugin-sdk/src/testing/fake-plugin-host.ts

  Line 5 in ad79bbb

  import { CronExpressionParser } from "cron-parser";

All four are optional peers of the SDK, so npm installs none of them:

• bb/packages/plugin-sdk/package.json

  Line 175 in ad79bbb

  "cron-parser": {

The scaffold declares three of the four and misses cron-parser:

• bb/packages/templates/src/plugin-scaffold.ts

  Lines 1912 to 1913 in ad79bbb

  	"better-sqlite3": "^12.0.0",
  	hono: "^4.11.9",

zod is covered because generated server.ts imports it, so it sits in dependencies.

What you ruled out

• Not a stale lockfile: npm install --include=dev in a brand-new scaffold, twice, on two machines' worth of clean node_modules.
• Not the frontend harness: @get-bb/plugin-sdk/testing/app needs React, Testing Library and jsdom, and the skill correctly tells the author to add those. Only the backend entry is affected.
• Not a duplicate — searched open and closed issues for cron-parser, plugin scaffold, plugin new test.

Suggested priority and effort

Hits every plugin author who follows the guide's testing section, which is the guide's own recommended workflow. Workaround is one npm i -D cron-parser once you have decoded the error. Effort: one line plus a regression test.

AGENT GENERATED

[SawyerHood]

Reproduction & root-cause report: https://get-bb.github.io/reports/issues/2546.html

• Verdict: REPRODUCED · root-cause confidence: high
• Root cause (short): The backend test harness imports cron-parser, but the scaffold omits this optional SDK peer, so Node fails during module load.
• Linked PR review: Unblock first-plugin authoring: testable scaffold, correct SDK example, visible npm failure #2550 → REQUEST CHANGES — Its cron-parser fix is correct, but npmFailureDetail can discard all stderr when stdout has more than eight lines.
• Proposed fix: Add cron-parser to scaffold development dependencies. Add a manifest contract test that reads peerDependenciesMeta. Fix PR Unblock first-plugin authoring: testable scaffold, correct SDK example, visible npm failure #2550 to retain separate stderr and stdout tails.
• Caveats: The base SDK version 0.4.24 was unavailable on npm, so the repro used a local archive from the exact base commit. The host used Node 24 and npm 11, but the failure matched the Node 20 and npm 10 report. The revision adds the local Vitest configuration that the verifier needed. No app server was necessary.

The report has copy-paste repro steps, screenshots where the bug is visual, code permalinks at the base commit, and repro artifacts. It was independently re-run by a second agent (see its Verification section).

AGENT GENERATED: by GPT-5.6-Sol