Investigate `smoke-sharkey` timeout in Mastodon → Fedify unfollow scenario

[dahlia]

The smoke-sharkey workflow has been failing consistently on main.

Latest failing run:

• Workflow: smoke-sharkey
• Job: smoke
• Run: https://github.com/fedify-dev/fedify/actions/runs/25052396280
• Job log: https://github.com/fedify-dev/fedify/actions/runs/25052396280/job/73383369435
• Commit: 9071ca0

The current failure is in test/smoke/orchestrator.ts, specifically the Mastodon → Fedify (Unfollow) scenario:

✓ Mastodon → Fedify (Follow)
✓ Fedify → Mastodon (Follow)
✓ Fedify → Mastodon (Create Note)
✓ Mastodon → Fedify (Reply)
✗ Mastodon → Fedify (Unfollow): Error: Timed out waiting for: Undo in harness inbox
✓ Fedify → Mastodon (Unfollow)

The failing assertion is here:

await pollHarnessInbox("Undo", (a) => !knownIds.has(a.id));

The test does confirm the server-side relationship is cleared before waiting for the inbox activity, so the failure appears to be specifically that Sharkey does not deliver an Undo(Follow) activity to the Fedify harness after POST /api/v1/accounts/:id/unfollow.

Recent runs show the same failure pattern, including:

• https://github.com/fedify-dev/fedify/actions/runs/25042122881
• https://github.com/fedify-dev/fedify/actions/runs/24951152094

There is also a Sharkey-side Mastodon API error in the collected logs:

Exception in mastodon endpoint GET /api/v1/accounts/lookup: TypeError: Cannot read properties of undefined (reading 'id')

That may be related to the account lookup fallback in the orchestrator, or it may just be a noisy Sharkey bug that the existing Misskey-native fallback already works around.

Things to investigate:

• Confirm whether Sharkey 2025.4.6 is expected to federate Undo Follow when unfollowing a remote ActivityPub actor through the Mastodon-compatible API.
• Check whether the smoke test should wait for a different signal for Sharkey, or whether the test setup is putting Sharkey into a state where the relationship is cleared locally without federation delivery.
• Add better logging around harness inbox deliveries and Sharkey outbound delivery for this scenario, so future failures distinguish “not emitted”, “not delivered”, and “delivered but rejected.”
• Decide whether to fix the Sharkey smoke harness, adjust the assertion for Sharkey-specific behavior, or pin/update the Sharkey image if this is a regression in that image.