diff --git a/__tests__/bundle/ownersTreeLoadArms.test.ts b/__tests__/bundle/ownersTreeLoadArms.test.ts
new file mode 100644
index 00000000..41b06c4f
--- /dev/null
+++ b/__tests__/bundle/ownersTreeLoadArms.test.ts
@@ -0,0 +1,68 @@
+import type { FakeGithub } from './fakeGithub'
+import { afterAll, afterEach, beforeAll, describe, expect, it, vi } from 'vitest'
+
+import { blobSha, prCommentEvent } from '../utils/ownersFixtures'
+import { start } from './fakeGithub'
+import { helpersFor, ownersProbe, ownersReads, queueRead, repo, token } from './helpers'
+import { runBundle } from './runBundle'
+
+vi.setConfig({ testTimeout: 30_000 })
+
+// the failure arms of the complete-tree OWNERS loader in src/utils/owners.ts (loadOwnersTree), driven through
+// dist/index.js by `/approve` on a pull request: the recursive tree listing of the base tip cannot be read, or an
+// OWNERS blob answers without content to decode. Each fails the run naming the base tip before anything is written.
+// The truncated-tree probes are covered by the owners probe arms test added in #320 (not yet merged).
+describe('dist/index.js OWNERS tree loading failures', () => {
+  let gh: FakeGithub
+  const { expectCommandThenConfig, routeOwners } = helpersFor(() => gh)
+
+  const rootOwners = 'approvers:\n- bob\n'
+  const rootBlobRead = `GET ${repo}/git/blobs/${blobSha('OWNERS')}`
+
+  beforeAll(async () => {
+    gh = await start()
+  })
+  afterEach(() => gh.reset())
+  afterAll(() => gh.close())
+
+  function runApprove() {
+    return runBundle({
+      eventName: 'issue_comment',
+      payload: prCommentEvent('/approve', 'bob'),
+      inputs: { ...token, 'prow-commands': '/approve' },
+      apiUrl: gh.url,
+    })
+  }
+
+  // the failed command, then the post-command sweep's config reads, then tide's own reads of the pull request
+  // and the base branch before its merge-queue dequeue; nothing is written
+  function expectFailedLoad(result: Awaited<ReturnType<typeof runBundle>>, command: string[]) {
+    expect(result.status, result.stdout).toBe(1)
+    expect(result.errors.some(e => e.includes('error loading OWNERS files at basesha'))).toBe(true)
+    expect(gh.requestsMatching('POST', /\/issues\//)).toEqual([])
+    expect(gh.requestsMatching('PUT', /./)).toEqual([])
+    expect(gh.requestsMatching('GET', /\/contents\/OWNERS/)).toEqual([])
+    expectCommandThenConfig(command, [`GET ${repo}/pulls/1`, ownersProbe, queueRead])
+  }
+
+  it('a tree listing that fails other than 404: /approve fails naming the base tip; no blob is read', async () => {
+    // the first matching route wins, so the failing listing goes in before routeOwners' complete one
+    gh.route('GET', `${repo}/git/trees/basesha`, { status: 500, body: { message: 'boom' } })
+    routeOwners({ OWNERS: rootOwners }, ['sdk/x.go'])
+
+    const result = await runApprove()
+
+    expectFailedLoad(result, ownersReads)
+    expect(gh.requestsMatching('GET', /\/git\/blobs\//)).toEqual([])
+  })
+
+  it('an OWNERS blob answering without content: /approve fails naming the file and the base tip', async () => {
+    gh.route('GET', `${repo}/git/blobs/${blobSha('OWNERS')}`, { status: 200, body: { sha: blobSha('OWNERS'), size: 0 } })
+    routeOwners({ OWNERS: rootOwners }, ['sdk/x.go'])
+
+    const result = await runApprove()
+
+    expectFailedLoad(result, [...ownersReads, rootBlobRead])
+    expect(result.errors.some(e => e.includes('invalid OWNERS file returned from GitHub API for OWNERS'))).toBe(true)
+  })
+})