Fixed all three items:

• Pruned expired nextByChat entries.
• Queued sends per chat so one chat’s wait doesn’t block another, preserving both pacing limits.
• Added pruning, cross-chat polling, and stubbed-fetch TelegramTransport tests.

All 14 example tests pass. node check-skill.mjs build-chat-bot and git diff --check pass.

Only three files under build-chat-bot/example/ changed. No dependencies, configuration, or token handling changed.

The review is complete. Findings are in .imd-findings.json at the repository root, and no project files were changed.

Verdict on the assignment question. The new tests do exercise the real code with injected clocks. The TelegramTransport test drives the real class with a mocked global fetch and the pending-timer ManualClock. The queueing test runs the real Bot and ScriptedTransport through the same pacer class. The eviction test reads the real pacer's map through the ScriptedTransport. I ran all three new tests against the previous commit's transport and bot. All three fail there and pass now, so they are genuine regression tests rather than tests shaped to the implementation. The suite passes on Node 24 and the skill checker reports ok.

Findings, ranked by severity.

• Medium, pre-existing, scope observation. One rejected reply in a poll batch makes the poll throw, the offset is lost, and the main loop retries the same offset every 5 s. Telegram then returns the same batch, so the bot is stuck and re-sends every other reply in the batch each round. I reproduced this with a stub transport where one chat's send rejects: after three rounds the offset was still 0 and two innocent chats had each received their reply three times. The sequential loop had the same stuck behaviour, but the new concurrent poll widens the duplicates to the whole batch. Fixing it needs an author decision on whether a failed send should fail the poll at all.
• Low, efficiency. Waiters for the overall slot are not reserved. They all wake at the same instant, one claims, the rest re-sleep, so sleep calls grow as N squared with the number of chats queued at once. Measured with the ManualClock: 465 sleeps for 31 chats, 499,500 for 1000. Under the system clock each fractional sleep becomes two timers because setTimeout truncates. Both rate limits were still honoured in a real-clock run, so this is not a limit violation.

Checked and found correct. Per-chat ordering under concurrent polls, eviction while another waiter sleeps, queue-map cleanup after success and after rejection, rejection propagation without unhandled-rejection leaks, the floating-point edge in the 31-message test, and whether a later arrival can jump ahead of a waiting chat on the real clock. That last one did not reproduce.