[littlenano]

The subscriber sweep drops subscribers whose get_chat_member reports user not found. An id Telegram cannot resolve as a chat participant also surfaces as

can not check subscriber Telegram { user_id: 8592764017, … } in chat -1001455914104:
A Telegram's error: Unknown error: "Bad Request: PARTICIPANT_ID_INVALID"

which is an ApiError::Unknown (teloxide has no variant for it), so it was only logged as a warning on every update while the subscriber stayed subscribed forever.

What the error means

• Telegram documents PARTICIPANT_ID_INVALID as "The specified participant ID is invalid", raised by channels.getParticipant, the MTProto method behind getChatMember.
• It is not a reliable "account deleted" signal: Random "Bad Request: PARTICIPANT_ID_INVALID" errors with getChatMember and banChatMember tdlib/telegram-bot-api#802 reports it for {user_id, chat_id} pairs that are entirely valid, sometimes returning left for the same request minutes later, and one report ties it to users the bot never interacted with and therefore cannot resolve.

Either way the id cannot resolve as a member of the chat, so it cannot be mentioned there: keeping the subscription changes nothing. sweep_subscribers() therefore treats it like user not found and removes the subscriber with an info log instead of a warning.

Other API errors (chat not found, retry after, network, …) still keep the subscriber and warn, and a member status that is simply not a member was already handled by is_member().

Verification

• cargo test --all-targets: 9 passed (the sweep mechanics are covered by update_subscribers_removes_invalid_and_renames; the error classification is a two-line match, not worth a test that would only restate the constant)
• cargo clippy --all-targets, cargo fmt --check: clean
• Merged with current main (post dependency update, rustc 1.99.0): cargo check --all-targets clean, cargo test 14 passed

[mergify]

Queued — the merge queue status continues in this comment ↓.

[mergify]

Merge Queue Status

• ✅ Entered queue — 2026-10-22 06:55 UTC · Rule: default · triggered by @linyinfeng with the merge queue checkbox
• ✅ Checks passed · on draft merge queue: checking #17 on main (c810c81) #23
• ✅ Merged — 2026-10-22 06:56 UTC · at 8a6c37e4e2e5603691e35688baef052ce484a7a7 · rebase

This pull request spent 1 minute 19 seconds in the queue, including 36 seconds running CI.

Required conditions to merge

• #check-failure = 0
• check-success = check