diff --git a/__tests__/bundle/blunderbussSettings.test.ts b/__tests__/bundle/blunderbussSettings.test.ts
new file mode 100644
index 00000000..55b2d718
--- /dev/null
+++ b/__tests__/bundle/blunderbussSettings.test.ts
@@ -0,0 +1,88 @@
+import type { FakeGithub } from './fakeGithub'
+import { Buffer } from 'node:buffer'
+import { afterAll, afterEach, beforeAll, describe, expect, it, vi } from 'vitest'
+
+import labelFileContents from '../fixtures/labels/labelFileContentsResp.json'
+import pullReqOpenedEvent from '../fixtures/pullReq/pullReqOpenedEvent.json'
+import { start } from './fakeGithub'
+import { helpersFor, repo, token } from './helpers'
+import { runBundle } from './runBundle'
+
+vi.setConfig({ testTimeout: 30_000 })
+
+// alice approves at the root; bob and carol review sdk/
+const ownersFiles: Record<string, string> = {
+  'OWNERS': 'approvers:\n- alice\n',
+  'sdk/OWNERS': 'reviewers:\n- bob\n- carol\n',
+}
+
+function yamlFile(text: string) {
+  const file = structuredClone(labelFileContents)
+  file.content = Buffer.from(text).toString('base64')
+  return file
+}
+
+// the configured `blunderbuss:` section driven through dist/index.js on `pull_request opened`: the bundle suite
+// otherwise runs blunderbuss at its defaults (and `request_count` through /auto-cc)
+describe('dist/index.js blunderbuss settings', () => {
+  let gh: FakeGithub
+  const { routeOwners } = helpersFor(() => gh)
+
+  beforeAll(async () => {
+    gh = await start()
+  })
+  afterEach(() => gh.reset())
+  afterAll(() => gh.close())
+
+  function configure(section: string, pull: Record<string, unknown> = {}) {
+    gh.route('GET', '/repos/Codertocat/.project/contents/prow.yaml', { status: 200, body: yamlFile(`blunderbuss:\n${section}`) })
+    routeOwners(ownersFiles, ['sdk/x.go'], pull)
+    gh.route('POST', `${repo}/pulls/1/requested_reviewers`, { status: 201, body: {} })
+  }
+
+  function requested(): string[][] {
+    return gh.requestsMatching('POST', /\/pulls\/1\/requested_reviewers$/).map(r => [...(r.body as { reviewers: string[] }).reviewers].sort())
+  }
+
+  async function opened() {
+    const result = await runBundle({ eventName: 'pull_request', payload: pullReqOpenedEvent, inputs: token, apiUrl: gh.url })
+    expect(result.status, result.stdout).toBe(0)
+    expect(result.errors).toEqual([])
+    return result
+  }
+
+  it('ignore_authors skips the pull request of a listed author, matched case-insensitively', async () => {
+    configure(`  ignore_authors: ['CODERTOCAT']\n`)
+
+    const result = await opened()
+
+    expect(result.stdout).toContain('blunderbuss: ignoring pull request by codertocat')
+    expect(requested()).toEqual([])
+  })
+
+  it('exclude_approvers leaves only the reviewers as candidates', async () => {
+    configure(`  exclude_approvers: true\n`)
+
+    await opened()
+
+    expect(requested()).toEqual([['bob', 'carol']])
+  })
+
+  it.each([
+    ['one reviewer is already requested, so one more is picked', ['dave'], 1],
+    ['two reviewers are already requested, so nobody is', ['dave', 'erin'], 0],
+  ])('max_request_count: 2 caps the request when %s', async (_name, already, picks) => {
+    configure(`  max_request_count: 2\n`, { requested_reviewers: already.map(login => ({ login })) })
+
+    const result = await opened()
+
+    const posts = requested()
+    expect(posts.flat()).toHaveLength(picks)
+    if (picks === 0) {
+      expect(result.stdout).toContain(`blunderbuss: #1 already has ${already.length} requested reviewers, max_request_count is 2`)
+    }
+    else {
+      expect(['alice', 'bob', 'carol']).toEqual(expect.arrayContaining(posts[0]))
+    }
+  })
+})