Bot abandons game mid-play when stream drops (StopIteration)

[metaember]

Bug Description

When the game stream encounters a StopIteration (stream ends due to network blip, Lichess closing the connection, etc.), the bot unconditionally exits the game loop — even if the game is still in progress. This causes the bot to flag on time.

Root Cause

In lichess_bot.py lines 780-783:

except (HTTPError, ReadTimeout, RemoteDisconnected, ChunkedEncodingError, RequestsConnectionError,
        StopIteration) as e:
    stopped = isinstance(e, StopIteration)
    stay_in_game = not stopped and (move_attempted or game_is_active(li, game.id))

Issue 1: When StopIteration fires, stay_in_game is set to False unconditionally (not stopped is False), bypassing both the move_attempted check and the game_is_active() check. A stream ending doesn't mean the game ended — it could be a transient network issue.

Issue 2: move_attempted is reset to False at the top of each loop iteration (line 726). So if the bot made a move on iteration N, and the exception fires on iteration N+1, move_attempted is already False. The fallback game_is_active() queries /api/account/playing, which can return stale data if called immediately after making a move (race condition).

Steps to Reproduce

1. Bot is playing a game
2. Bot makes a move successfully (HTTP 200 from /api/bot/game/{id}/move/{move})
3. Game stream connection drops (StopIteration on next(lines))
4. Bot exits game loop, kills engine
5. Opponent makes a move, bot never responds
6. Bot flags on time

Observed Behavior

From logs:

20:26:56 - Bot plays Qe2, move accepted (HTTP 200)
20:27:11 - Bot checks /api/account/playing, concludes game is over, quits engine
20:27:11 - "Game over" logged, engine process exits
20:32:08 - gameFinish event arrives with status "outoftime" — bot flagged

The bot quit the engine ~15 seconds after its last move, while the game was still ongoing.

Suggested Fix

On StopIteration, the bot should verify the game is still active via game_is_active() (with a small delay to avoid the race condition) before exiting, rather than unconditionally giving up:

except (HTTPError, ReadTimeout, RemoteDisconnected, ChunkedEncodingError, RequestsConnectionError,
        StopIteration) as e:
    stopped = isinstance(e, StopIteration)
    if stopped:
        time.sleep(1)
    stay_in_game = move_attempted or game_is_active(li, game.id)

Environment

• lichess-bot version: 2026.2.13.1 (commit 960bcad)
• Running in Docker on Linux

[MarkZH]

Have you implemented this change in your own copy of lichess-bot? I would be surprised if the game stream could resume after a StopIteration exception.

[MarkZH]

I tried implementing your suggested fix along with an extra log message:

if stopped:
    logger.debug("Got StopIteration; sleeping for one second.")
    time.sleep(1)
stay_in_game = move_attempted or game_is_active(li, game.id)

I only saw the StopIteration message after a game completed. Have you implemented the change in your own copy of lichess-bot? If so, please post logs (from the lichess_bot_auto_logs folder) of a game restarting after a network interruption.